LA— 10256-MS

DE85 016209

LA-10256-MS

UC-11Issued: June 1985

Radiological Survey and Evaluation of theFallout Area from the Trinity Test:

Chupadera Mesa and White SandsMissile Range, New Mexico

Wayne R. HansenJohn C. Rodgers

DISCLAIMER

This report was prepared as an account of work sponsored by an agency of the United StatesGovernment. Neither the United States Government nor any agency thereof, nor any of theiremployees, makes any warranty, express or implied, or assumes any legal liability or responsi-bility for the accuracy, completeness, or usefulness of any information, apparatus, product, orprocess disclosed, or represents that its use would not infringe privately owned rights. Refer-ence herein to any specific commercial product, process, or service by trade name, trademark,

DISTHIBUTION OF THIS DOCUMENT IS U N I : " ' '

Los Alamos National LaboratoryLos Alamos, New Mexico 87545

CONTENTS

ABSTRACT 1

CHAPTER 1—SUMMARY 2

CHAPTER2—INTRODUCTION AND BACKGROUND 5

I. THE DOE RESURVEY PROGRAM 5

11. THE TRINITY TEST 5

III. THE TRINITY FALLOUT ZONE 5

IV. THE RESURVEY OBJECTIVES 10

CHAPTER 3—METHODS AND \PPROACH 11

I. APPROACH II

II. METHODS II

A. In Situ Measurement II

B. Sampling and Analysis 12

CHAPTER 4—RESULTS 14

I. TOTAL AREA 14

A. Trinity Data Analysis: ""Cs in Soil 14B. Trinny Dam Analysis: :IM:4>I Pu in Soil 18C. Other Fission and Activation Products in Soils 20D. Natural Radioactivity in Soils 23

II. DATA SUMMARY FOR SOILS 24A. Plutonium in Soils 24B. Cesium-137 in Soils 25C. Strontium-90 in Soils 27

ill. AIRBORNE RADIOACTIVE MATERIALS 27

IV. EXTERNAL PENETRATING RADIATION 29

CHAPTERS—POTENTIAL DOSE EVALUATION AND INTERPRETATION 40

I. BASES OF DOSE ESTIMATES AND COMPARISONS 40

II. POTENTIAL DOSES FROM THE CURRENT CONDITIONS IN THE

TRINITY TEST FALLOUT DEPOSITION AREAS 43

III. SPECIAL CONSIDERATIONS 43

REFERENCES 45ACRONYMS AND ABBREVIATIONS 48UNITS 49GLOSSARY 50

APPENDIX A—DATABASE TR1N DAT 52APPENDIX B—LOG OF FIELD OPERATIONS FOR SURVEY OF

TRINITY, 1977 82APPENDIX C—IN «T.TU INSTRUMENT CALIBRATION 86APPENDIX D—INTERPRETATION OF DATA 91APPENDIX E—SOURCES AND EVALUATION OF RADIATION

EXPOSURES HO

FIGURES

1. Central New Mexico. The sue of the Trinity Test is noted on theleft part of the map 6

2. Trinity test tower. Oscura Mountains in the background 73. Range after test 84. Diagram of Trinity GZ fences 95. The fallout zone from the Trinity test as determined by a 1945

beta-gamma survey 96 Outline map of the contaminated area as determined by 1947 and 1948

survey. A transeel was established with numbered laterals 107. General map of The Trinity fallout area and the measurement locations 148. Comparison of in situ and soil sample estimates of total n7Cs inventory 209. White Sands Missile Range. Bingham. and Chupadera Mesa sample locations 25

10. Sample locations for the San Antonio area 2511. External radiation dose rates measured at Trinity Site. June 9. 1983 to June 23. 1983 39

C-l. Nr/o as a function ofn 88C-2. N f/s= Nr/ •

TABLES

1. ESTIMATES OF RISK BASED ON EXPOSURES ATTRIBUTABLETO RESIDUAL CONTAMINATION IN AREAS OF FALLOUTFROM THE TRINITY TEST 3

11. RiSK COMPARISON DATA 4III. "7 SOIL CONCENTRATION DATA !6IV. CHUPADERA MESA 137Cs PROFILE DATA 17V. GROUND ZERO TO CHUPADERA MESA 117Cs PROFILE DATA 18

VI. l37Cs INVENTORY ESTIMATES 18VII. COMPARISON OF IN SITU AND SOIL SAMPLE ESTIMATES

OF "7Cs TOTAL INVENTORY 19VIII. TRINITY SOIL CONCENTRATION OF :i":4UPu 21

IX. GZ ENVIRONS AND CHUPADERA MESA m-4l lPu SOU-CONCENTRATION PROFILE ESTIMATES 22

X. SURFACESOIL CONCENTRATION OF :38Pu AND:MUWPu RATIOS 22XI. 1977 ESTIMATES OF 1-cm AND TOTAL PLUTONIUM INVENTORY. . . . 23

XII. ACTIVATION AND FISSION PRODUCTS IN BULK SOIL SAMPLESAT TRINITY GZ AREA 23

XIII. SOIL CONCENTRATIONS OF NATURALLY OCCURRINGGAMMA-EMITTERS 24

XIV GROUND ZERO SURFACE MEASUREMENTS 26XV. WHITE SANDS MISSILE RANGE FALLOUT ZONE SOIL

MEASUREMENTS 28XVI. BINGHAM AREA SOIL MEASUREMENTS. US HIGHWAY 3^0

CORRIDOR 29XVII. CHUPADERA MESA SURFACE SOIL MEASUREMENTS 30

XV11I. FAR FALLOUT ZONE SURFACE SOIL MEASUREMENTS 31XIX. SAN ANTONIO AREA SURFACE SOIL MEASUREMENTS 32XX. AREAL CONCENTRATIONS OF 117Cs 33

XXI. CHUPADERA MESA IN SITU i r Cs DATA FOR SOILS BYLAND FORM 34

XXII. ""Sr BACKGROUND INFORMATION 35XXIII. POTENTIAL CONTRIBUTIONS OF RF.SUSPENSION OF : "Pu

AIRBORNE RADIOACTIVITY 36XXIV. EXTERNAL RADIATION EXPOSURE SUMMARY FOR

IN SITU DATA 37XXV. EXTERNAL PENETRATING RADIATION MEASUREMENTS AND

ESTIMATES OF CONTRIBUTIONS FROM TRINITY FALLOUT 38XXVI. STANDARDS AND GUIDES FOR RADIATION AND

RADIOACTIVITY 41XXVU. INCREMENTAL DOSES 44

C-l. COUNT RATE PER UNIT FLUX AT THE DETECTOR, Nr/. AS AFUNCTION OF MEASURED a 89

D-l. NORTHERN NEW ME/K ) BACKGROUND REFERENCE VALUESFOR NATURAL OR FALLOUT LEVELS OF RADIOACTIVITY 92

D-II. 1983 PLUTONIUM DATA FOR SPLIT SPOON CORE SAMPLESFROM GROUND ZERO AREA 94

D-III. 1983 n :Eu DATA FROM SPLIT SPOON CORE SAMPLES INGROUND ZERO AREA 95

D-IV. JUNE 1983 PLUTONIUM DATA FROM TRINITY GZ AREA 96D-V. PARAMETERS FOR ESTIMATION OF RESUSPENSION OF RADIO-

NUCL1DES USING MASS LOADING 97

vn

D-Vl. ENRICHMENT FACTORS FOR RESUSPFNDABLE PARTICLES 98D-V1I. INHALATION DOSE FACTORS USED 99

D-VIII. ESTIMATED DOSES FROM INHALATION OF MRBORNEMATERIALS FROM RESUSPENS1ON 100

D-IX. INPUT PARAMETERS FOR DOSE CALCULATIONS 101D-X. INGESTION DOSE FACTORS USED 102

D-XI. INGESTED RADIONUCLIDES 103D-XII. ESTIMATED DOSES FROM INGESTION OF FOODS GROWN

IN EACH AREA 104D-XIII. ESTIMATED AIR CONCENTRATION FOR SOIL PREPARATION

FOR HOME GARDEN 105D-XIV. ESTIMATE DOSES FROM SOIL PREPARATION FOR

HOME GARDEN 106

E-I. RADIOACTIVE MATERIALS OF PRIMARY INTEREST IN THERADIOLOGICAL SURVEY 113

E-II. UNITS OF RADIOACTIVITY USED IN THE RADIOLOGICALSURVEY 115

E-I 11. STANDARDS AND GUIDES FOR RADIATION ANDRADIOACTIVITY 122

V l l l

Preface

This series of reports results from a program initiated in 1974 by the Atomic Energy Commission(AEC) for determination of the condition of sites formerly utilized by the Manhattan Engineer District(MED) and the AEC for work involving the handling of radioactive materials. Since the early 1940s, thecontrol of over 100 sites that were no longer required for nuclear programs has been returned to privateindustry or the public for unrestricted use. A search of MED and AEC records indicated that for some ofthese sites, documentation was insufficient to determine whether or not the decontamination work done atthe time nuclear activities ceased is adequate by current guidelines.

This report contains data and information on the resurvey effo't and the effect of residualcontamination as a result of nuclear weapons development programs conducted in this area. The reportdocuments the present radiological conditions within the realm of today's sophisticated instrumentationand the impact on any future area development.

This report was prepared by the Environmental Surveillance Group (HSE-8), Health, Safety andEnvironment Division of Los Alamos National Laboratory. This report was compiled and written byWayne R. Hansen and John C. Rodgers with major contributions from William D. Purtymun, Donald MVan Etten, John D. Purson and Kenneth H. Rea. Field work in 1977 was directed by Daniel W. Wilson.Field in situ measurements and laboratory sample counting were directed by John Kirby and DouglasSever of La-> rence Livermore National Laboratory. Other Los Alamos personnel involved in measure-ments were Thomas E. Hakonson, John W. Nyhan, Edward Rahrig, Thomas E. Buhl, and Alan K.Stoker.

IX

Radiological Survey and Evaluation of theFallout Area from the Trinity Test:

Chupadera Mesa and White Sands Missile Range, New Mexico

by

Wayne R. Hansen and John C Rodgers

ABSTRACT

Current radiological conditions were evaluated for the site of the first nuclear weapons test, the Trinitytest, and the associated fallout zone. The test, located on White Sands Missile Range, was conducted aspart of the research with nuclear materials for the World War II Manhattan Engineer District atomicbomb project. Some residual radioactivity attributable to the test was found in the soils of Ground Zero onWhite Sands Missile Range and the areas that received fallout from the test. The study considered relevantinformation including historical records, environmental data extending back to the 1940s, and new dataacquired by field sampling and measurements. Potential exposures to radiation were evaluated for currentland uses. Maximum estimated doses on Chupadera Mesa and other uncontrolled areas are less than 3%of the DOE Radiation Protection Standards (RPSs). Radiation exposures during public visits to the U.S.Army-controUed Ground Zero area are less than 1 mrem per annual visit or less than 0.2% of the RPS fora member of the public. Detailed data and interpretations are provided in appendixes.

1. SUMMARY

This evaluation of current conditions at the site of thefirst nuclear weapon test (Trinity) and the associatedfallout areas is based on extensive field measurementsand sampling followed by interpretation of the resultingdata. The study was completed as pan of the FormerlyUtilized Sit. medial Action Program (FUSRAP)sponsored by the U.S. Department of Energy (DOE).

The Trinity test was part of the research conducted forthe World War II Manhattan Engineer District (MED)atomic bomb project. The test was conducted on July 16,1945. Measurements of radiation levels at Ground Zero(GZ) and in the fallout zone began ihe same day. Thefallout was blown in a northeast direction over WhiteSands Missile Range. Chupadera Mesa, and otherranching areas. The land uses in the fallout zone remainthe same today. White Sands Missile Range extendsnorth of GZ about 17 km (!0 miles). Privately ownedranch land extends along the path of the fallout zone tothe northeast with Chupadera Mesa areas of interest atabout 50 km (30 miles) northeast of GZ. Land use onChupadera Mesa is for cattle grazing. Areas farther outin the fallout area also are used for cattle grazing withsmall areas of crop production.

This study considered all available relevant informa-tion. Records and reports provided the history of themeasurements of radiation and radioactivity at GZ andthe fallout zone. Environmental measurements and sam-ple results, some extending back to the 1940s, werereviewed for information on trends and patterns. Datafrom these and special radioecology research studieswere compiled to provide a basis for planning ihe acquisi-tion of new data. Most of the new data consist of severalhundred field measurements and samples of soil andvegetation.

The findings, based vn interpretation of the: data, areexpressed in this summary as maximum increments ofrisk to hypothetical individuals exposed to the existingconditions. Individual risks of cancer from exposure toradiation were calculated from factors derived from theNational Academy of Sciences 1980 study. Potentialexposures to radiation for various possible mechanismswere generally calculated as 50-year committed dose

equivalents resulting from 1-year exposures to accountfor cumulative doses from those radioactive materialsretained in the body for varying periods after initialexposure. Exposure to natural background results inexactly the same kind of risks. The risk-estimating factorswere applied to natural background radiation asmeasured in north central New Mexico to provide onecontext for judging the significance of other risks. Peopleliving in northern New Mexico incur an estimated in-cremental risk of cancer mortality of 8 chances in10 000. or a probability or 8 x I0~4, from a 50-yearexposure to the natural radiation background. The natu-ral radiation background dose, about 150 mrem eachyear, includes contributions from cosmic radiation, natu-ral terrestrial radioactivity, and natural radioactivityincorporated in the body. A larger perspective is that theoverall U.S. population lifetime risk of mortality fromcancers induced b\ all causes is currently about 2chances in 10, or a probability of 0.2.

The maximum likely incremental risks from allmechanisms of potential exposure in the areas havingresidual radioactivity attributable to the residual radioac-tivity range from about 2 chances in 10 000 (2 x 10~4) inthe restricted use area to a minimum of 6 chances in10 000 000 00G(6x lO*10) under current conditions ofland use as summarized in Table I. The mechanismsinclude direct exposure to penetrating radiation andinhalation of resuspended dust.

Table I gives the incremental risks of cancer mortality,bone cancer, and lung cancer, along with the 50-yeardose commitments from which they were calculated. Allcf the dose commitment values are considered overstatedto some degree because assumptions used in their deri-vation were made to maximize estimates of potentialeffects. All of the dose commitments are small fractionsof those permitted above natural background andmedical exposure by the DOE Radiation ProtectionStandards (RPSs). Maximum estimated doses onChupadera Mesa and other uncontrolled areas are lessthan 3% of the RPSs.

Another context for judging the significance of theserisks associated with exposure to radiation, whether from

natural background or other sources, is a comparisonwith risks from other activities or hazards encountered inroutine experience. Table II presents a sampling of risksfor activities that may result in early mortality and annualrisks of death from accidents or natural phenomena.Because not all of the risks are directly comparable, thevalues for mortality risks shown in Table I overlap therange of values for risks shown in Table II. The largestincremental risks from the exposure to the residual

contamination are about the same size as the incrementalrisk of a 1000-mile automobile trip; most are smal'er thanthe annual risk of death from lightning.

Some differences in future conditions will result fromradioactive decay processes. While the total doses fromtransuranium elements will noi change appreciably, thedoses from "°Sr and 137Cs will decrease 50% in about 30years. At the GZ area the external radiation doses willdecrease about 90% in the same 30 year period.

TABLE I

I S I I M A 1 I S OF RISK BASED ON EXPOSURES ATI RIBU 1 ABLH TO RtSlDUALCONTAMINATION IN AREAS OF FALLOUT FROM THE TRINITY TKST"

Locations/Exposure

Hypothetical Resident

O Z

Inner lenceBetween fences

White Sands Missile RangeHlnghamChupadera MesaFar Fallout ZoneSan Antonio

Other HypotheticalExposures

40 h of Work in GZinner fenced area

Security PatrolsAnnual visitor at Open

House of Trinity Site

OverallCa

Mortality

2.0 •1.1 •14 »4.0 .

1.8 >7.4 >2.2 >

4.6 >9.0 >

1.2,

10 4

I'J 4

10 "10 7

; 10 ': 10 '( 10 '

i 10 -1

i i o • • •

< 10 '

Incremental Risk

Increasedon 50 Yenr

Cancer

2 . 2 •

8 .7 •

6 . 3 •

5 .7 •

1.2 .4.8..6.0 >

: 10 '. 10 *• 1 0 "

. 10 "

. 10 'i 10 "( 10 '

Probability BasedCommitted Doses'

Cancer

1.4 • 10 7

2.3 •. 10 "

8 .7 • 10 "

4.2 - 10 "1.6 x 10 '3.1 < 10 "1.8 x 10 "

Cancer

I.I4.21.07.52 73.61.5

< 10 *- 10 "x 10 '« 10 "< 10 'x 10 "x 10 "

ExternalWholeBody

1700880

141.7

13

51.7

80.75

1.0

Committed Dosemrem in 50

from

Body

2 Radiation Protection Standard

134

6700

500 500 1500 1500 1500

"All calculations based on current conditions.hLocaMons are described in more detail in Chapter 4.'Probabilities are expressed in evponential notation; they can be converted to expressions of chance bytaking the numerical value in front of the multiplication sign (x) as "chances" and writing a one (I)followed by the number of zeros given in the exponent. For example, 9.7 x 10"' becomes 9.7 chances in10 000 000.

TABLE II

RISK COMPARISON DATA

Individual Increased Chance of DeathCaused by Selected Activities

Increase in ChanceActivity of Death

Smoking 1 pack of cigarettes (cancer, heart disease) 1.5 x 10 'Drinking 1/2 liter of wine (cirrhosis of the liver) 1 x 10~6

Chest x-ray in good hospital (cancer) 1 x 10~6

Travelling 10 .niles by bicycle (accident) 1 x l O 6

Travelling 1000 miles by car (accident) 3 x lO"6

Travelling 3000 miles by jet (accident, cancer) 3.5 x 10"6

Eating 10 tablespoons of peanut butter (liver cancer) 2 x 10"7

Eating 10 charcoal broiled steaks (cancer) 1 x 10"1

U.S. Average Indiviuual Risk of Death in One YearDue to Selected Causes

Cause Annual Risk of Death

Motor Vehicle Accident 2.5 x 10~4

Accidental Fall 1 x 10"4

F:-es 4 x 10"5

Drowning 3 x 10~5

Air Travel 1 x 10"5

Electrocution 6 x 1CT6

Lightning 5 x 10"7

Tornadoes 4 x I0~7

U.S. Population Lifetime Cancer Risk

Contracting Cancer from All Causes 0.25Mortality from Cancer 0.20

2. INTRODUCTION AND BACKGROUND

I. THE DOE RESURVEY PROGRAM

The 1977 and 1983 survey of the Trinity Site wascarried out as part of the DOE program aimed atformulation of any remedial actions for Manhattan Engi-neer District (MED) or Atomic Energy Commission(AEC) sites. In the DOE program, files were reviewed todetermine if residual radioactive contamination mightexist at the sites. If the radiological conditions wereuncertain, a survey of the area influenced by the site wasperformed. The files and special studies in existence forthe Trinity Site indicated a survey would be necessary toquantify the radiological condition of the 32-year-oldfallout area from the first nuclear explosion at WhiteSands Missile Range in New Mexico, July 16, 1945.

Several studies of the fallout zone had been carried outbefore the resurvey. These included surveys immediatelyafter the test in 1945, studies by University of California,Los Angeles (UCLA) in 1948, 1950, and 1951. In 1973and 1974, the U.S. Environmental Protection Agency(EPA) carried out an extensive soil sampling program forplutonium in the area. The study included air samplerslocated on Chupadera Mesa and in Socorro, New Mex-ico. Starting in 1972 and continuing until 1979, LosAlamos Scientific Laboratory, conducted specialecological studies of the movement of 137Cs and pluto-nium isotopes on study plots on Chupadera Mesa andnear Ground Zero (GZ) located on White Sands MissileRange. Factors influencing the survey were the history ofthe Trinity test, previous studies of the fallout zone, andthe stated objectives of the Formerly Utilized SitesRemedial Action Program. Each of these factors isdiscussed in more detail in following paragraphs.Separate chapters are devoted to the resurvey plan, theresults, and interpretation of the data. Appendixes areincluded that contain the historic data base, the raw datafrom this study, a log containing locations of samplelocations, calibration methods for the in situ detectorsystem used, and calculational methods used for estima-tions of radiation dose equivalents from any residualfallout radionuclides.

II. THE TRINITY TEST

The Trinity test of the first atomic bomb took place onJuly 16, 1945, on White Sands Missile Range in CentralNew Mexico. The test resulted in deposition and dispersalof radioactive fallout over a portion of central andnortheastern New Mexico. Figure 1 is a map of thegeneral area with Trinity Site marked on the lower left-hand corner of the map. The device was mounted on a100-foot tower with cables for instruments and timingstrung to shelters 9144 m (10 000 yds) away. Figure 2 isa photograph of the tower-mounted device before the test.The Oscura Mountains are in the background of thephotograph about 5 miles east of the test area.

Weather on the day of the test started out being cloudyand windy with scattered showers. At 2:00 a.m., the testwas rescheduled from 4:00 a.m. to 5:30 a.m. At 4:00a.m., the rain stopped and at 4:45 a.m., a favorableweather forecast indicated the 5:30 a.m. time was accept-able. Weather remained cloudy after the test, as observedby planes sent to drop sensors during and after the test.1

After the test, a crater and zone of melted sand werecreated (Fig. 3). The green fused sand is referred to asTrinitite in many reports. The GZ area has been desig-nated a National Monument. As noted earlier, GZ islocated on White Sands Missile Range, and access iscontrolled throughout the year. Once annually, the publicis invited for a controlled visit to the site, usually in themonth of October. Figure 4 is a diagram of the GZfenced area included in the public visits.

III. THE TRINITY FALLOUT ZONE

Following the test, measurements were made to estab-lish the trajectory of the fallout cloud and the depositionpattern over Chupadera Mesa and areas northeast of GZ.Measurements during 1945 were made across the falloutpattern to outermost edges of the fallout zone.

Figure 5 is a depiction of the fallout zone based onbeta-gamma surveys of the soil surface following the test.The fallout followed a northeasterly direction paralleling

\ c/ifluriro \ ALBUQUERQUEI r.fs \ -*^

Ncwkii

us \Mij.il.

IRI nv sinWilRLOS FIRST A10SIC BOMB

^ JULY 16 1945 HOSED TO PUil

Fig. /. Central New Mexico. The site ofthr Trinity Test is noted on the lower left part cj the map.

Fig. 2. Trinity test tower. Oscura Mountains in thebackground.

ihe west of U.S. Highway 54 (Fig. 1). The cloud passedover Chupadera Mesa, where localized areas of higherlevels were observed.

Another beta-gamma survey carried out in 1947 and1948 confirmed the earlier observations and added detailto the mapping of the area.2 Figure 6 is an outline map ofthe contaminated area taken from the 1947 and 1948studies.2 A primary transect reference line was estab-lished in the 1947 study. The transect of 34° 56" startedat the Section Marker at GZ At every 4930 feet,reference points were marked for the first 11 points. At

point 12, the reference points were marked every 9000feet. From this primary transect, reference line lateralswere extended 90° right and left. Sampling and studyareas were established according to the lateral numbers.For example, an area of special stuoy on ChupaderaMesa at lateral 21 (about 28 miles from GZ) is referred toas area 21. This type of designation is referred to inreports of several studies of the Trinity fallout zone.

Since 1945, radioactive decay has resulted in substan-tial reductions of the fallout levels so that only the long-lived radionuclides 90Sr, m Cs , and "9Pu with traces ofeuropium, remain. In the intervening years, environmen-tal and biological transport processes such as erosion,sedimentation, and biotic uptake have acted on the initialsurface deposition to redistribute these long-lived radio-nuclides. A number of studies were carried out tocharacterize the radionuclide distribution and redistribu-tion in the years following the test.

The first major studies were carried out between 1947and 1950. These studies emphasized radionuclide con-centrations including plutonium for soils and plants,particularly on Chupadera Mesa, the crater region, andthe region north of the crater, but still on White SandsMissile Range,3'4 The studies included characterization inthe soils and plants of the area.

Plant studies included a study of the revegetation ofGZ. Studies were also carried out that involved descrip-tions of the movement of small mammals, reptiles, andbirds in the area surrounding GZ.5 The results of thesestudies have been included in considerations of the designof this study.

In summary, elevated levels of plutonium and fissionproducts were measured in the fallout pattern. Themaximum concentrations in soil outside the fenced areaof GZ were detected on Chupadera Mesa about 28 milesfrom GZ. The authors suggest a localized rain showermay have scrubbed a portion of the fallout cloud.4 Duringthe study period ot 1947 to 1950, there also was observedsome downward migration of fission products in the soil.However, wind erosion in the crater area of GZ wasrelatively more important than water in spreading thecontamination.6 Plutonium was found in amounts up to19 pCi per square foot at area 21. No plutonium wasfound in samples collected 3 miles south of GZ.7 Studiesof plant invasion of the crater area through 1964 con-cijded that, while the area had not returned tc climaxvegetation, ustributicnal patterns were controlled bywater availability, soil conditions, and timing of climaticvariants rather than radiation.8

Crater and heat effects mark GZ on White Sands Missile.

Fig. 3. Range after test.

In 1972. a series of special studies of the plutoniumdistribution were started by Los Alamos Scientific Labo-ratory. Soil- vegetation, and rodent samples along thefallout transect were obtained at GZ and out to 56.4 km(35 miles).9 Soil samples from GZ indicated a relativelyuniform vertical distribution of plutonium in the 30-cm-deep soil samples. Increased migration of plutonium intothe soil was observed. Concentrations of plutonium invegetation and rodents were too low to make validcomparisons. From the data taken, four intensive studyareas were established at 1.6 km, 16 km. and 44 km. inaddition to a control site south of GZ.10 About half of the239.24opu j n fae Trinity fallout ione soils was found at the5- to 20-cm depth in 1973 compared with total plutoniuminventories being detected only in the upper 5 cm of soil

in previous studies (21 to 25 years). Penetration depths of239.240pu j n t 0 j j ^ f an o u t 2 O n e SOJIS w e r e r e i a t e t[ t 0 the

presence of subsoil horizons containing carbonate ac-cumulations and to the extent of rainwater penetration

into the soil profiles.10'" Studies of plutonium as relatedto concentrations on vegetation indicate concentrationratios as high as 1.0 for dry weights.121 ae range for forbswas 0.04 to 1.1 and grasses 0.05 to 1.2. Contamination ofplant surfaces with soil particles is considered the causeof plant-soil ratios higher than observed in greenhousestudies.

In 1973 and 1974, the EPA sampled and analyzedsoils from across the region of the Trinity fallout field for239Pu and 240Pu in the top 5 cm of the surface soil."Before publication, the results of the survey and the fieldnotes from the sampling were forwarded to Los Aiamosby the EPA. The highest surface plutonium level wasobserved on the White Sands Missile Range. The GZsample contained 1100 nCi of 239 ' :4 (1pu per square meterof soil surface. A soil sample taken approximately 3.2 km(2 miles) north of GZ contained 100 nCi per squaremeter, but neighboring sample locations gave plutoniumvalue factors of 4 to 10 times lower.

600 BOO 1

IQO ISO ZOO

SCfllES

Fig. 4. Diagram of Trinity GZ fences.

-35'

106

- 3 4 '

'ALBUQUERQUECLINES

CORNERS

WILLARO

MOUNTAINAIR

GRAN QUIVIRA

SOCORROSANANTONIO

WHITE SANDS !MISSILE <RANGE '

•CARRIZOZO

Fig. 5. The fallout zone from the Trinity test asdetermined by a 1945 beta-gamma survey.

Consistent with earlier findings of the initial falloutdistribution, plutonium levels generally decrease withdistance from GZ and with lateral distance from thecenterline. The increase or Chupadera Mesa, some 20 to30 miles from GZ, is also observed in the data. Thehighest level reported by EPA on the mesa at a singlelocation was 86 nCi per square meter. Backgroundvalues, that is, the minimum values, were reported at lessthan 1 nCi per square meter.

The EPA study also included carrying out air samplingfor airborne plutonium. An air-sampling station wasestablished at Socorro, New Mexico, and another air-sampling station was established at Monte Puerto Ranchon Chupadera Mesa. Air samples were collected over a10-month period. The samples were analyzed for239,24o.238pu T h e g^onx, station acted as a control areabecause it was located out of the fallout zone. The 238Puresults from both locations were below the detection level

CLAUNCH I

KILLING PLAINSREGION

BACKGROUNDPERIMETER

PRIMARY TRANSECTREFERENCE Ufti

.SECONDARY TRANSECTREFERENCE LINE

, NE BOUNDARY OFI TRINITY RESION

Fig. 6. Outline map of the contaminated area asdetermined by 1947 and 1948 survey. A transectwas established with numbered laterals.

on many of the samples. Often, the results for a

also were below detection limits, and only the datapertaining to the detected plutonium were reported. Theprimary results of the air sampling indicated that the airconcentrations were well below the proposed EPA limitfor transuranics deposited on soils. The conclusion of thestudy indicated that, while higher plutonium levels couldbe found at very localized individual sites, the samplingdensity used in the study on Chupadera Mesa makes itunlikely that grossly higher levels are present in the areaexceeding the EPA proposed guidance.

Because the EPA study limited itself to plutonium, itwas decided that the 1977 resurvey of the fallout zonewould include fission product and activation productmeasurements in addition to confirmatory plutoniummeasurements. Data for the resurvey concentrated inareas in the far fallout zone (the area north of WhiteSands Missile Range, and in particular, ChupaderaMesa) because, at the time, it was felt this was the mostimportant area.

IV. THE RESURVEY OBJECTIVES

As previously mentioned, a number of studies havetaken special views of either the early distribution offission products, or later, the distribution of plutonium.The special Los Alamos ecology studies concentrated onintensive studies of four relatively small areas, 1 hectarein size. The EPA study concentrated on the characterization of plutonium mainly in the Chupadera Mesa area.These data are included in the data base of this study(Appendix A). The objective of this study, however, wastwofold. The first objective, that of the resurvey program,was to design a sampling program that would allow theestimation of radiological dose to people living in the areafor current land uses. These land uses are for grazingcattle and small home gardens. It is anticipated that GZand the White Sands Missile Range will remain in controlof the U.S. Army. Second, because a data base existed fora number of years and it is known from the earlier studiesthat wind and water played a major role in redistributionof the fallout material, it was decided that the studywould also make special measurements to investigateredistribution of the materials from the actions of windand rain. Because high-resolution germanium lithium-drifted [Ge(Li)] gamma detectors now exist, and areusable under field situations, it was decided to use theLawrence Livermore Laboratory mobile radiation detect-ion system. Use of the germanium detector with a pulseheight analyzer in a mobile unit enabled the measurementof the distribution of fission products in soil in a rapidmanner.

Redistribution of the surface-deposited fission products and plutonium was an important considerationof the studies carried out during the UCLA series in 1947to 1951. A strong redistribution of surface soil by bothwind and rain was observed. Flash floods do occur in thearea and tend to move soils and sediments in runoffchannels in large quantities. Points of deposition for thesesediments that are moved by heavy water events areusually low points that are often dug out to collect thewater for livestock watering. Therefore, the study in-cluded a number of measurements where the U7Cscontent was measured both upslope and at the finaldeposition point for redistribution of the fission productsand probably of plutonium also.

To evaluate the significance of the residual contamina-tion at the GZ location, a series of core samples wastaken in 1983.

10

3. METHODS AND APPROACH

This study was designed to supplement existing data on the distribution of fallout from the Trinity Testto allow estimation of potential radiation doses based on land use. The sampling program took advantageof previous studies of the fallout area, as well as special studies of-small areas of the fallout zone.

I. APPROACH

Previous surveys had determined the extent of thefallout area and general concentrations of surface depo-sition of fallout. Later studies by Los Alamos NationalLaboratory concentrated on the mechanisms for re-distribution of the fallout in several intensive studyareas.14 In the case of the U.S. Environmental ProtectionAgency studies, the principal investigator provided fieldnotes so sample locations could be relocated for furthersampling.

The sampling programs were carried out during twotime periods. In 1977 the far fallout zone, ChupaderaMesa, and areas around GZ on White Sands MissileRange were sampled. Because time and resources werelimited, maximum use of previous survey resuits guidedthe plan for characterization of the residual falloutradionuclides. Also, the loan of a van with instrumenta-tion and personnel from Lawrence Livermore NationalLaboratory allowed use of real-time data for decisionsabout measurement locations in the field. In 1983 a set ofmeasurements and samples was taken at GZ. Analysis ofthe 1977 survey data had indicated more detailed infor-mation on the depth distribution of radionuclides at GZwould be necessary for engineering studies of the area. Inboth surveys, in situ measurements with a germaniumlithium-activated [Ge(Li)] high-resolution gamma-rayspectrometer and special sampling methods were used toobtain information on the concentrations and location ofradionuclides.

II. METHODS

A. In Situ Measurement

In planning the Trinity survey effort, it was determinedthat the utilization of in situ Ge(Li) spectrometry would

provide a number of advantages over sole reliance ontraditional soil-sampling techniques for obtaining an in-ventory of radionuclides in the soils of a very largeTrinity fallout field. The following considerations weretaken into account.

(a) The relatively short counting time required toobtain a satisfactory gamma spectrum for a sam-ple (30 min compared with 1000-2000 min in thelaboratory for a 100-g soil sample) allows a poten-tially larger number of sample locations to beexamined. Alternatively, it allows the reallocationof laboratory Ge(Li) analysis time to the necessarysoil profje concentration determinations in sup-port of the in situ measurements.

(b) Local inhomogeneities in soil radionuclide concen-tration (both in depth and in small regions) areautomatically averaged because the detector isresponding to photons from a very large quantityof soil (several metric tons compared with a fewhundred grams in a laboratory system).

(c) Combining the inherently high resolution of aGe(Li) spectrometer system with a mobile detectorand support system permits immediate feedback inthe field of both radioisotope identity and relativeactivity (cpm), which allows on-site decisions to bemade concerning what additional or differentmeasurements might be needed and where.

The methodology and instrumentation for and feasibil-ity of utilizing in situ Ge(Li) spectroscopy for identifyingand quantifying radionuclides distributed in soil havebeen investigated and successfully demonstrated at sev-eral laboratories over the past several years.15"" For theTrinity resurvey, equipment and techniques developed bythe Lawrence Livermore National Laboratory (LLNL)were utilized through a cooperative arrangement. Anoverview of the system and its calibration are found inpublished reports.17

11

The response of a closed-end, cylindrical Ge(Li) de-tector, placed at a fixed height (1 meter) above the soil, isan energy-dependent function of the angular response ofthe detector and the flux of unscattered photons incidenton the detector per unit of soil radioactivity. Normally,calibration of this response involves laboratory measure-ments and calculational procedures independent of thegeometries of the distributed sources to be evaluated.Radionuclidas that have been redistributed through thevertical soil piofile from an initial surface deposition (forexample, fallout) are usually assumed to be exponentiallydistributed in this calibration calculation. As acrosscheck of the laboratory calibration and the suit-ability of the exponential distribution assumption, anempirical calibration factor for 137Cs was derived as well.

Although detector response to a source does dependon such variables as the mass attenuation coefficients anddensities of soil and air under field conditions, the crucialvariable is the specification of the relaxation depth of theactivity heing measured (that is, the inverse of the powerof the exponential distribution function). Under ce^caincircumstances this parameter can be readily and reliablyestimated, as in the case of fresh fallout of short-livedradionuclides (7Be, for instance) or the case of naturallyoccurring radionuclides such as uranium, which tend tobe uniformly distributed in soil. But the case of aged,long-lived fallout radionuclides deposited over as largeand varied terrain as is found in the Trinity fallout fieldpresents a more difficult condition to interpret. Concen-tration profiles for I37Cs were determined at reasonablyrepresentative locations throughout the field by the tech-nique of soil sampling and laboratory Ge(Li) analysis. Asmight be expected, these distributions reflect in a complexway the effects of the wide differences in rainfall input,soil properties and depth, and vegetation type and den-sity, which occur over the range of low-elevation, drydesert terrain, through the grass and pinon-juniperhabitat of the mesas, to the conifer forests of the moun-tain slopes. Representative values were selected andassigned by judgment to each sample location. An effortto develop a linear box model of redistribution of l37Csfollowing deposition was made, but the many uncertain-ties in estimating the relevant parameters in the model ledto results judged to be of no more value than makingassignments on the basis of proximity to measuredprofile:, similarity of soil type, vagetation, elevation, andso forth.

B. Sampling and Analysis

Sampling of soils, sediments, and vegetation accom-panied most in situ measurements throughout the surveyarea. Of particular importance were soil profile samplestaken at the location of the in situ measurement. Thesesoil profile samples were used to develop a correctionfactor for calibration of the Ge(Li) detector system toaccount for the depth distribution of gamma-ray emittingraaionuclides.

The methods used for obtaining samples and subse-quent analysis considered the sensitivity of the systemsused and the survey design. At locations with changingtopographical features, additional soil samples weretaken to study plutonium and strontium distribution.These isotopes are not present in sufficient quantity fordetection by the in situ measurement system used.

Soil samples were obtained using a 12.8-cm- (5-in.-)diameter ring that was pushed or pounded 5 cm (2 in.)into the soil. Soil was removed from around the ring byuse of a shovel and hand trowel. An aluminum sheet waspushed under the ring and both soil and ring were liftedout. The soil was collected in plastic bags labeled with thelocation identification and an indication of the depth andsoil horizon sampled. The procedure was repeated foreach soil profile sample, taking care to avoid crosscontamination. At each in situ measurement location,three 5-cm-deep soil profiles or a total of 15-cm- (6-in.-)deep samples were obtained. At selected locations, profiledepths to 40 cm (16 in.) were sampled.

Vegetation samples were collected using grass shearsto cut the grass or weeds within 1 to 5 cm of the soilsurface. For trees, new growth and the last year's growthwere collected. Samples were placed in plastic bags withnotation of the plant species and the identification num-ber for that location. Notes were made on the vegetativecover, measured slope, and soil characteristics. Topo-graphic features of the surrounding area also were noted.Additional vegetation samples were collected for laterverification of species types.

Soil and vegetation samples were transported daily tolaboratories at New Mexico Institute of Mining andTechnology in Socorro, New Mexico. Samples wereplaced in drying racks of window screen on wood framesin an unused greenhouse. After initial air drying, heatlamps were used to dry the samples to constant weight.Constant weight was attained in 1 hour under the heat

12

lamps. A drying time of 2 hours for both soils and plantswas used as routine practice. After they were dried, soiland plant samples were pulverized using Waring Blen-dors. Vegetation samples were packed into cans byoverfilling above the top of the container. A manual canse 'er compressed the sample while the lid was fastenedto the can. About 80 g of dried vegetation was sealed inthe can for later counting on a laboratory Ge(Li) detectorsystem. At the same time, 10.05 g of sample was weighedinto a plastic sample bottle and labeled for transport toLos Alamos National Laboratory, where radiochemicalanalyses were conducted. Soil samples werehomogenized and about 360 g filled the cans. Samples of10.05 g of each soil or sediment sample were placed insmall plastic bottles and labeled for transport to LosAlamos National Laboratory radiochemical laboratories.

Because the soils were anticipated to contain greaterquantities of radionuclides than vegetation, a separate

laboratory was used for soil handling. Samples from theGZ area were handled with special precautions becauseof higher radionuclide contents. Special laboratory clean-ing before and after handling these segregated sanplesminimized cross-contamination potential.

Vegetation and soil samples were counted on a Ge(Li)system at New Mexico Institute of Mining and Tech-nology as an initial screening method for radionuclideidentification. Final analysis of the samples for gamma-emitting radionuclidcs was conducted by LLNL withcalibrated laboratory Ge(Li) systems and data reductionaccomplished using computer codes.20

Vegetation and soil samples sent to the Los Alamosenvironmental surveillance radiochemistry laboratorieswere analyzed for 238Pu, 23''240Pu, and 90Sr.21 Plutoniumanalyses used standard digestion, anion exchange, plat-ing, and alpha spectroscopy methods. Stron*ium-90 anal-yses utilized standard '°Y ingrowth methods.

13

4. RESULTS

I. TOTAL AREA

For an overview of the amount of radioactive falloutfrom the Trinity Test, the data have been reviewed foroverall measurement of l37Cs, 239i24(lPu, and other radio-nuclides. Figure 7 is a general map of the Trinity falloutarea. Data points are designated as small squares. Thesolid lines divide the data base into areas of generalinterest for assessment of the r;:dionuclides on more area-specific bases. The data base was divided into areasdesignated: Trinity GZ, San Antonio, White Sands Mis-sile Range, Bingham, Chupadera Mesa, and Far FalloutZone. Section II of the Results presents the mean data byarea. Appendix A lists the data from all data basessummarized in the Results section of this report.

A. Trinity Data Analysis: U7Cs in Soil

There are three independent modes of measurement ofradionuclide content in Trinity soils used: (1) direct, insitu gamma,spectroscopy, (2) laboratory gamma spec-troscopy of canned soil samples, and (3) laboratoryradiochemical an alysis of soil samples. (See Chapter 2 ofthis report for details.) There is only limited overlap ofdetermination of specific radionuclides by these ap-proaches. In the case of U7Cs, only in situ spectroscopyand laboratory spectroscopy of canned samples wereapplied: one providing inventory estimates and the othersoil concentration data. In application, these two sourcesof information on 137Cs inventory are not totally inde-pendent. The in situ measurement requires knowledge of

' 0 10 20 30 40 50J i i i I

KILOMETERS

Fig. 7. General map of the Trinity fallout area and the measurement locations.

14

the vertical distribution pattern in the soils in the vicinityof the detector in order to be translated into an inventoryestimate. The soil sampling results can be used to providethis needed distribution estimate. A discussion of thereduction of these data to provide 137Cs inventory esti-mates follows.

Soil samples were collected at a large number oflocations throughout the survey area at locations wherein situ spectroscopy measurements were made (but not atevery such location). Usually samples were collected atthree consecutive 5-cm depth intervals. However, whenthese samples were processed, not all samples wereprepared and counted. Profiles for which complete ornearly complete 137Cs concentration data exist are shownin Table III.

An estimate can be made of the 137Cs concentration inthose samples that were counted, but for which no cesiumdata were reported based on the minimum detectableactivity (MDA). Ucing the MDA estimate in thoseinstances where a sample was counted but no 137Cs datawere reported provides an upper-bound estimate of inven-tory. One approach to estimating the MDA for 137Cs is toexamine the trend in uncertainty in the reported data. TheMDA can be taken to be the smallest amount of activitythat would likely be reported with an error not greaterthan some acceptable limit, say 33%. At an uncertaintyof 33%, the corresponding concentration is approx-imately 0.1 pCi/g. Another approach based on statisticalconsiderations, described in Appendix E, yields similarestimates.

Replacing MDA everywhere by the estimate of 0.1pCi/g substantially increases the number >if profileestimates. The profile characterization is by means of anexponential fitting function:

C = Co exp(-ax) (1)

where C is the concentration at depth x, Co is the surfaceconcentration, and a is the inverse relaxation depth of thedistribution. This relation can be justified theoretically onthe basis of a simple box model in which the soil profile ischaracterized by a sequence of boxes that exchangecontaminants over a period of time at a certain flow rate(A. T. Jakubide, Migration of Plutonium in Natural Soil,1977). To incorporate the uncertainties in the concentra-tion determinations into the profile characterization (thatis, into the determination of the inverse relaxation depthestimate), a logarithmic transformation of Eq. (1) ismade and the method of linear least squares applied with

some modification to compensate for the fact that,unadjusted, the least-squares estimate underemphasizesthe uncertainties for small values of C. (See Appendix C,least-squares fitting of an exponential function.)

The resulting alpha estimates for the Chupadera Mesaare shown in Table IV and GZ samples in Table V.Evidently, the mesa samples are characterized by ashallower profile (large alpha), and show less variabilitythan the GZ samples do. This reflects, perhaps, themechanical disturbance of GZ soils but also differencesin the original deposition processes over these two areas,the geochemistry of the respective soils, and other envi-ronmental factors such as precipitation frequency, in-tensity, and so forth.

An estimate of the inventory of l37Cs (nCi/m2) in thesesoils can be made utilizing the concentration and profiledata. Since there can be expected considerable mixing inthe topmost layer of soil, the average concentration at themidpoint in the 0- to 5-cm interval will be taken to berepresentative of the 0- to 2.5-cm interval as well. (Thisestimation should tend to overestimate the actual inven-tory because there is most likely a parabolic distributionshape in the near surface layers caused from depletionprocesses at the surface.) Then the estimate of theinventory in the 0- to 2.5-cm interval is given, for adensity of 1.5 g/cm3, by

ii.i = C2.j (PCi/g) x 2.5 cm x 1.5 (g/cm3)

x 104 (cmVm2) x 103 (nCi/pCi) = 37.5 C2.5 . (2)

Then the total inventory can be estimated over the rest ofthe profile assuming the fitted exponential distribution:

I,

2.5 + ( / " V - dxj(1.5)(!.O)(C2.5)

(3)

where the integral is approximated by one-half.A comparison of the in situ inventory estimates with

many of the soil sample estimates is possible and providessome measure of the compatibility of these two ap-proaches to inventory estimation (Table VI). Because ofdelays in processing of canned soil samples, assignmentof the a profile parameter for each sample location had to

15

TABLE III

137Cs SOIL CONCENTRATION DATA

Location

GZorMesa

GGGGGGGGGGGMMMMGMMMMMMMMMGMMMMM

LADB"No.

19901991198819892006200520122016?.0182014201920272026204520481987205320502057204921152116211820812080199221202071205820282059

0-5 cm

13.66.040.611.750.350.770.380.820.260.990.543.195.421.182.081.870.710.792.560.832.955.422.061.290.320.101.753.125.145.871.04

FSDb

0.0110.0360.4860.1220.1880.0310.2270.0320.1730.0330.0570.0170.0630.0340.0470.110.0560.0250.0170.0520.0270.0130.030.0320.0810.3440.0300.020.010.010.04

Concentration

5-10 cm

21.79.26

24.950.170.280.520.410.260.26

—0.380.120.480.220.130.16

————0.090.480.10

——0.181.0

——0.18

FSD

0.0130.0140.0240.1790.1850.0320.1270.240.058

—0.1080.1350.0970.0850.2740.291

——...—0.1920.0970.162

...—0.2820.040

——0.29

(pci/g)10-15 cm

6.98c

—

MDAd

——

MDA0.110.150.970.140.21

MDA0.080.19

MDA0.060.28

MDAMDAMDAMDAMDAMDA

0.11—

MDA0.140.08

MDAMDA

FSD

0.036—————

MDA0.1640.3550.0590.2990.155

MDA0.2240.296

MDA0.2040.221

MDAMDAMDAMDAMDAMDA

0.163—

MDA0.350.34

MDAMDA

"LADB - Los Alamos Data Base.bFSD - Fractional Standard Deviation.c— means no data taken.dMDA - Minimum Detectable Activity.

16

TABLE IV

CHUPADERA MESA 137Cs PROFILE DATA

LADB"No.

20^62027202820452048204920502053205720582059207120802081211521162118

CCone at2.5 cm(pCi/g)

5.423.195.871.181.080.830.790.712.565.141.046.870.320.292.955.422.06

FSD (B)b

0.0130.0170.0100.0340.0470.0520.0250.0560.0170.0100.0400.0200.0810.0320.0270.0130.030

a(cnT')

0.330.330.530.320.220.220.100.250.330.420.240.390.110.270.490.480.47

FSD (a)

0.640.090.160.100.290.500.400.320.330.290.450.230.480.410.170.060.16

Sequenci

0.40.20.40.20.40.20.20.20.40.40.40.40.20.40.70.70.7

Note: Mean a = 0.3235 and a = 0.1281.

"LADB - Los Alamos Data Base.bFSD - Fractional Standard Deviation.

be made on the basis of limited information. Thus, thereare a number of significant differences between theassumed a for in situ estimation and the fitted a for soilsample estimation (Table VII). However, corrected in situestimates of inventory based on detector efficiencies as afunction of a (Chapter II) were made corresponding tofitted a's and are shown in column 5 of Table VII.

Figure 8, a plot of soil-sample gamma in situ inventoryestimates, suggests that the two estimation proceduresyield similar results. A paired t-test was calculated forboth corrected and uncorrected data (excluding sample2014, which is a GZ sample), with the result that the two

sample means are not significantly different at the 90%confidence limit in either the corrected or uncorrectedcases. The a parameter correction appears to make onlya small difference in comparability. Possibly the fact thatthe in situ technique is averaging over a considerablylarger volume of soil at each sampling location than thecorresponding soil samples is a compensating effect tothe uncertainties in estimating a.

Thus, it would appear that the in situ 137Cs totalinventory estimates are comparable with soil samplingestimates with an uncertainty on the order of 50%.

17

TABLE V

GROUND ZERO TO CHUPADERA MESAu 'Cs PROFILE DATA

TABLE VI

l37Cs INVENTORY ESTIMATES

A. Chupadera Mesa

LADBa

No.

1987198819891990199119922005200620122014201620182019

aLADBbFSD-

Conc at2.5 cm(pCi/g)

1.870.611.75

13.606.040.100.770.350.380.990.820.260.54

FSD (C)b

0.110.4860.1220.0110.0360.3440.0310.1880.2270.0330.0320.1730.057

- Los Alamos Data BastFractional S

a (err ')

0.37

0.120.400.060.080.120.080.040.030.0020.210.020.08

Standard Deviation.

FSD (a)

0.24

0.170.070.010.042.170.142.122.510.0060.214.270.43

LADBa

No.

2026202720282045204820492050205320572058205920712080

i.\JO 1

211521162118

1-cmInventory(nCi/m2)

81.347.8588.0517.7016.2012.4511.8510.6538.4

177.115.6

103.054.89

in is17.JJ

44.2581.3030.90

FSD

0.0130.0170.010U.0340.0470.0520.0250.0560.0170.010.040.020.081n nM0.0270.0130.030

TotalInventory(nCi/m2)

449.6264.6386.3

99.56114.187.7

148.169.2

212.4376.3104.0521.9

55.61 ?fi 0

200.9372.6142.9

FSDb

0.640.090.180.110.290.500.400.320.330.390.450.230.480 41

0.170.060.16

B. Trinity Data Analysis: 23»MOPu in Soil

Direct determination of the concentration and inven-tory of plutonium in Trinity soils was carried out by soilsampling and radiochemical analyses. Preliminary in-vestigation of the possibility of utilizing the determinationof 241 Am inventory as an indirect means of determining239.24Opu j n v e n t o r y p r o v ed unsuccessful because of anobserved very low concentration of 24lAm in the Trinitysoils, even in the vicinity of GZ.

The soil radiochemical results are tabulated in TableVIII. These data indicate a fairly rapid decrease inplutonium concentration with depth in most esses. Butthere are some significant exceptions such as at samplelocation 2072, which is a flat, grassy sediment trap onChupadera Mesa. Here, relatively high concentrations(>1 pCi/g) persist to a depth of 10 to 15 cm. Deepdistribution of plutonium might be expected to occur insuch sediment traps; however, no systematic attempt was

B. GZ to Chupadera Mesa

1987198819891990199119922005200620122014201620182019

28.059.15

26.25204.0

90.61.5

11.555.255.70

.14.8512.303.90

• 8.10

0.110.490.120.010.0360.3440.0310.188C.2270.0330.0320.1730.057

145.999.1

131.253710.01359.0

16.25173.25144.4204.3

7462.189.32

204.75121.5

0.260.510.200.010.052.170.143.10.230.030.214.20.43

"LADB - Los Alamos Data Base.bFSD - Fractional Standard Deviation.

18

TABLE VII

COMPARISON OF IN SITU AND SOIL SAMPLEESTIMATES OF '"Cs, TOTAL INVENTORV (nCi/rn2)

LADB"No.

20122014

20162018201920262027204920502053205720582059207120802081211521162118

Assumeda

0.20.030.200.200.200.400.200.200.200.200.400.400.400.400.200.400.700.700.70

InventoryIn SituReported

236.6858.2

84.5890.92

26.43540.0314.0139.6125.2189.0158.7323.4211.3388.7

81.5135.583.784.4

100.0

a

5.7325.29

4.462.96

1.1949.28

4.743.533.434.013.044.22

3.405.352.912.742.122.232.23

InventoryCorrected15

for a

701.31501.9

84.6269.5

99.7597.9'232.7139.6185.6189.0175.7323.4284.8388.7

120.8168.098.398.7

120.9

InventorySoil Sample

Estimate

204.37462.1

89.3

204.8121.5449.6264.6

87.7148.169.2

212.4376.3104.0521.9

55.6120.0200.9372.6142.9

FSDC

0.230.030.21

0.170.100.640.090.500.400.320.330.290.450.230.480.410.170.060.16

Measureda

0.030.0020.21

0.020.080.330.330.220.100.250.330.420.24

0.390.110.270.490.480.47

"LADB - Los Alamos Data Base.bThe number of counts in the 137Cs photopeak is converted to.nCi/m2 by a detector efficiency termN f/s, which is a

r ncuon of a. The ratio of the efficiency values for the assumed a and actual measureda from profile data vas used to evaluate a corrected in situ estimate.CFSD - Fractional Standard Deviation.

made to fully explore the extent of vertical redistributionof plutonium in soils.

As in the case of 137Cs soil concentrations profile data,these plutonium data can be fitted by an exponentialdistribution model in most cases to provide an estimate ofdistribution with depth, and thereby, inventory. Lea it-squares fitting of these data (where possible) with anexponential fitting function yield the results tabulated inTable IX.

These profile characterizations clearly point to thehighly variable or indeterminate distribution conditions of

the GZ area due possibly to mechanical disturbance inthe characteristics of the fallout materials, and so forth.The fit of the shapes of the concentration depth profiles toan exponential function is reasonably good onChupadera Mesa; but there are some notable exceptions.Some of the cases where there is considerable uncertaintyin the profile parameter a are probably attributable tovery low concentrations, especially at greatest depth, withconsequent poor recovery and counting statistics. Others(sample 2080, for example) may reflect other processes at

19

IN-SITU

Fig. 8. Comparison of in situ and soil sample estimatesof total niCs inventory.

work affecting vertical redistribution rather than infiltra-tion, such as disturbances by burrowing rodents, cattle,or big game animals.

Concentrations cf 238Pu in these soils are so low as tomake reliable estimates of profile distributions, and con-sequently total inventory, impossible. Table X illustratesthe order of magnitude of some surface (0- to 5-cm)concentrations and corresponding 238Pu/239Pu ratios.There is apparently about 20 times more 239Pu than 238Puin the surface soils, independent of location.

The 23»-MOpu inventory estimate was made utilizing thesame strategy as was used for 137Cs inventory estimates,that is, by assuming an essentially uniform concentrationin the 0- to 2.5-cm layer, and a decreasing exponentialdistribution over the remainder of the profile. On theseassumptions, the 0- to 1-cm inventory I, (most readilyavailable for resuspension) and the total inventory ITestimates are given, assuming again a density of 1.5g/cm3,

I, = 15C2.5 ± 0C

and

V °c2 (4)

These two inventories are tabulated in Table XI forthose cases where adequate data exist. Samples for whicheither the profile estimate could not be made or for whichthe uncertainty in the surface concentration and/orprofile a estimates were too great to provide useful totalinventory estimates, still have a surface inventory esti-mate listed. Evidently in the case of GZ environs samples,only the near surface inventory estimate is usable.

C. Other Fission and Activation Products in Soils

In addition to cesium and plutonium, several fissionproducts and activation products from the Trinity eventand more recent Chinese nuciear tests were detected bythe Ge(Li) systems used. The activation and fissionproducts from the relatively recent fallout were detectableat most locations by observing the 95Zr and 95Nb gammarays in the in situ spectra. The average 95Zr (half-life, 64d)22 areal concentration for the approximately 2500 mi2

surveyed was 2.4 ±0.12 nCi/m1 and the 95Nb (half-life,35.1 d)22 average concentration was 3.8 ± 0.1^ nCi/m2.The range of concentrations was from undetectable to 6.6nCi/m2 for 9!Nb. Of the 116 measurement locations for137Cs, 9!Zr was detected at 88 locations and 95Nb at 92locations.

Other short-lived radionuclides detected by the in situGe(Li) system were 7Be and 103Ru. The relatively shorthalf-lives of 53.4 d22 for 7Be and 39.3 d22 for 103Ru alsoidentify these radionuclides as being part of fallout fromthe 4-megaton Chines? nuclear test on November 17,1976.7 The 7Be concentration on an areal basis averaged8.1 ± 0.7 nCi/m2 with a range from undetected to 26nCi/m2. Of the 116 locations monitored for 137Cs, 62locations had detectable 7Be. Only 22 out of the 116locations contained detectable I03Ru with concentrat.onsfor the area surveyed averaging 0.21 ± 0.04 nCi/m2. Therange was from undetectable quantities to 1.9 nCi/m2.

The in situ gamma spectra and laboratory analyses ofsoil indicated the presence of the activation and fissionproducts 60Co, 152Eu, and 155Eu. Because of the longerhalf-lives associated with these radionuclides, the quan-tities present are considered to be from the Trinity test.The half-life ef 60Co is 5.27 yr; 152Eu, 14 yr; anci 153Eu, 5yr.22 The areal concentration of these radionuclides attwo GZ locations as measured by in situ methodsindicated 5000 nCi/m2 and 50 nCi/m2 of 60Co and LI x104 r.Ci/m2 and 1.2 x 103 nCi/m2 of 153Eu. For areas

20

TABLE VIII

TRINITY SOIL CONCENTRATION OF "'-""Pu

LADB"No.

1*982001200320092014201b20182026202"202820372047

2052'204820492057205920602065207120722073207620802082208420962097

21152118211921202121

:GZ or

TABLE IX TABLE X

GZ ENVIRONS ANDCHUPADERA MESA »''24OPu SOIL

CONCENTRATION PROFILE ESTIMATES

SURFACE SOIL CONCENTRATION OF:38Pu AND 238«'Pu RATIOS

LADB"

No.

19951998

2001200320092016201820262027202820372047204820492052205720592060206520712072207320762080208220842096209721152118211921202121

Surface SoilConcentration

C = Coneat 2.5 cm

(pCi/g)

(uniform

FSD (C)b

Inverse RelaxationDepth of

a (cm"1)

Profile

FSD (a)b

ly uncontaminated at background)(a indeterminate—disturbed soil at

(a positive—disturbed soil GZ)

3.80.48

0.050.04

0.860.001

(a positive—disturbed soil)(a indeterminate-—surface deposit

3.511.714.071.830.980.390.250.120.701.211.060.271.544.58

0.030.030.040.030.04

0.050.040.07

0.030.060.040.04

0.030.03

0.670.380.720.620.190.560.280.250.340.530.191.010.320.11

GZ)

16.512.9

only)0.060.050.050.070.060.365.74

0.090.030.190.053.380.120.02

(a indeterminate—only surface sample teste

0.440.030.951.230.210.610.250.180.17

0.030.150.040.040.060.050.160.070.06

0.410.050.910.610.930.280.490.520.35

0.313.530.440.157.190.090.540.784.03

(a positive—disturbed soils in stream chanr

0.69 0.04 0.06 0.24

Location

2009201420162018204720602065207220732076208221192121

Surface Coneof 238Pu

(PCi/g)

0.023

0.00590.0040.2040.0450.0480.0120.224

0.3230.0160.0460.0080.041

FSDa

0.170.320.500 010.110.11

0.170.0040.050.130.110.330.10

238,239pl

0.050.040.030.050.050.050.04

0.050.050.040.050.050.06

"LADB - Los Alamos Data Base.bFSD - Fractional Standard Deviation.

"FSD - Fractional Standard Deviation.

outside of GZ, 60Co was detected at 21 locations,whereas I52Eu and I35Eu were detected at only fourlocations in situ. The average 60Co areal concentrationarea from ground zero areas was 2.5 ± 1.5 nCi/m2. The60Co distribution for the fallout area does not correlatewith the l37Cs area concentrations. Away from groundzero areas, the correlation coefficient for 60Co and l37Csis 0.05. There was no correlation latwuen 60Co and ""Srin soils.

Laboratory counting of the soil samples in tuna cansprovided additional information about the fissionproducts from the Trinity fallout at GZ. The followingradionuclides: 60Co, I37Cs, I33Ba, 152Eu, li4Eu, and 155Euwere detected in most soil samples. Table XII indicatesthe range of soil concentrations of the radionuclidesdetected. The range is wide but not unusual in view of thedisturbances of the Trinity GZ area. The area wasplowed and bladed in 1945 to remove materials from thesurface. In particular, the fused sand and soil calledTrinitite was being picked up by visitors as a memento ofthe event. The surface was bladed and the Trinitite wasburieH in trenches in the GZ area in 1952. Other

22

TABLE XI TABLE XII

1977 ESTIMATES OF 1-cm AND TOTALPLUTONIUM INVENTORY (nCi/m2)

ACTIVATION AND FISSION PRODUCTS INBULfc SOIL SAMPLES AT TRINITY GZ AREA

LADS'No.

199519982001200320092014

20162018202620272028203720477.048204920522057205920602065207120722073207620822084209721152118211921202121

•LADB"FSD-

1-cm 2 ] 'PuInventory (I,)

Bkg«0.01)364.5973.5

57.07.22.51.8

10.152.725.7

61.127.514.75.93.7

1.810.518.215.94.1

23.168.7

100.56.6

14.318.59.23.82.7

2.63.3

10.4

FSDb

(IT)

0.020.020.050.04

0.050.080.040.030.030.040.030.04

0.050.040.070.030.060.040.040.030.030.030.030.040.04

0.050.160.070.060.130.04

- Los Alamos Data Base.

Total "'PuInventory (I,)

e

c

c

'

c

210.2131.6237.4112.9114.1

25.1"

11.757.179.6

123.4•

129.9796.3

•

32.651.376.4

•

17.011.9

•

1

Fractional Standard Deviation.

FSD°(IT)

—

0.080.130.070.110.320.66

0.S90.090.360.27

0.370.18

0.760.490.25

1.27

1.55......

Total inventory not calculated because of inadequate data(FSD> 3).

radionuclides identified with low confidence and expectedin fallout gamma-ray spectra were 1MCe and 12!Sb. Theselatter radionuclides are likely from the Chinese nucleartests.

In selected scil samples from areas off the White SandsMissile Range, the predominant fission products detectedwere 137Cs and l35Eu. These samples are from a largearea including Chupadera Mesa, Gallinas Peak, and thefar fallout areas northeast of New Mexico State Highway14. For laboratory counting, the 0- to 5-cm and 10- to15-cm samples were selected for counting for in situ

Isotope

60Co

137Cs

>»Ba

132Eu

Soil SampleInterval (cm)

0-5-

10-0-5-

10-0-5-

10-0-5-

10-05-

10

"Not detected.

51015510155101551015

•510

•15

Range of Cone(pCi/g)

12-12

0.12-4.2-

0.52-0.79-

1.6-0.58-N.D

12240N.D

1610

N.D

60

182148163.82.9

• 1 . 5 a

-1300-270-340-76- 15-17

detector calibration. Selected 5- to 10-cm samples werecounted, but they were fewer in number.

The mean values for the 15!Eu activity in soil were 0.17± 0.12 pCi/g for the 0- to 5-cm depth and 0.14 ± 0.07pCi/g for the 10- to 15-cm depth. An analysis of varianceindicates the means are equal at 'he 99% level ofsignificance. The same samples have unequal means for137Cs concentration with the greatest amounts in the 0- to5-cm samples. The equal concentrations of I55Eu concen-trations in the 0- to 5-cm and 10- to 15-cm soil depthsindicate possible movement of Eu deeper into the soilwith time. For a deeper soil sample of 20 to 25 cm in thesame region but for only one location, the 155Eu concen-tration was 0.23 pCi/g.

D. Natural Radioactivity in Soils

The in situ Ge(Li) detector system detects the gamma-emitting primordial radionuclides and these radiationscan be used for calibration of the detector for energy. Thequantities of 40K are determined directly. The quantities

23

of U 8 U and 232Th are determined from the quantities ofgamma-emitting daughter products. Use of the daughterproducts assumes radiological equilibrium between theparents and daughters with minimal or unimportantchemical redistribution in the soils.

The " K concentration, listed in Table XIII, averaged17.7 ± 0.56 pCi/g for the region surveyed with a range ofvalues from 3.4 to 42 pCi/g. The wide range of values isconsistent with the variable geological features of theregion surveyed. The N C R P report on natural back-ground radiation in the U.S. summarizes the concentra-tions of major radionuclides in rock types and soil.23 Theexpected range of values would be predicted to bebetween 2 pCi/g for carbonate rocks and 40 pCi/g forsalic rocks. The geological formations of the region arecomposed of limestones and sandstones with a small areaat the top of Gallinas Peak being intrusive rock identifiedas rhyolite. The highest value, 42 pCi/g, was from aregion of volcanic rocks in a canyon area where 40Kcontent would be expected to exceed 30 pCi/g. Soils forthe total U.S. averaged 12 pCi/g for in situ measurementstaken by Lowder ct al. in 1964 compared with theaverage of 18 pCi/g for this study.34

The concentrations of the natural radionuclides 231Thand 238U also varied within the study region. The 232Thaverage concentration for all in situ locations was 0.94 ±0.04 pCi/g with a range from 0.12 pCi/g to 2.8 pCi/g.The 238U concentrations for in situ locations averaged0.90 ± 0.03 pCi/g with a range from 0.32 pCi/g to 2.0pCi/g. The highest values of 232Th were detected at thetop of Gallinas Peak where intrusive rocks occur. Thehighest uranium value was detected in an area thatintegrates water runoff in a basin area. Areas of exposedlimestone where soils were relatively thin contained the

TABLE XIII

SOIL CONCENTRATIONS OF NATURALLYOCCURRING GAMMA-EMITTERS

Rndionuclide

238U

101101101

Mean Cone.(pCi/g) ± S.E.

17.7 ±0 .560.94 ± 0.040.93 ± 0.03

Range(PCi/g)

3 .4 -420.14-2 .80.32 - 2.0

lowest concentrations of 232Th and 238U, as expected fromliterature values.23 '24

II. DATA SUMMARY FOR SOILS

The separation of the overall data base into smallerlocations of measurement of radionuclides generally fol-lowed topographic areas of the fallout area from theTrinity test. An artificiality of the boundary selection wasthe use of roads or a property boundary, which tends toresult in a mixture of topographic features. However,directions and distances from GZ and land use allcontributed to the choice of boundaries for separate datatreatment.

The areas are bounded in Fig. 7 by solid lines. TrinityGZ is illustrated in Figs. 4 and 11. Located within aspecial fenced area on the White Sands Missile Range,Trinity GZ is the area of ground disturbance left from theinitial test. Figure 9 indicates the sampling locations forthe White Sands Missile Range, Bingham area, andChupadera Mesa. Earlier surveys by Larson et al. andspecial studies by Hakonson et al. indicated localizedareas of higher fallout on Chupadera Mesa.6-9 Figure 7includes the sample locations for the far fallout area.Figure 10 indicates the location of samples in the SanAntonio area, which is west and out of the fallout path.

The soil data for each area are summarized in TablesXIV through XIX. The results listed in the tables aresummaries of statistical treatment of the data by area todetermine means and standard errors (standard deviationof the mean).25 The dates associated with the 2 3 9-2 4 'pudeterminations are the data from studies by Olafson andLarson in 1948 and 1950, Los Alamos in 1972, EPA in1973 and 1974, and Los Alamos in 1977 and 1983. Alsonoted is the depth of soil samples taken br uise thesampling schemes used by different investigators varied.

A. Plutonium in Soils

From Appendix D, the level of 2 3 9-2 4 Ppu in soils fromworldwide fallout deposited in northern New Mexico is0.008 ± 0.01 pCi/g. Of the areas listed in Tables XIVthrough XIX, only the San Antonio Area contains239-240pu -m s o y s a t c o n c e n t r a t ions as low as NorthernNew Mexico fallout levels. The other areas of the falloutzone all contain 239-240Pu above worldwide fallout levels.

The no action level proposed by the DOE RemedialAction Programs for 239-240pu is 100 pCi/g. The only

24

Fig. 9. White Sands Missile Range, Bingham, and Chupadera Mesa sample locations.

/

u

oSANANTONIO

GRANDE S

ft! Ml* ;

aWHITESANDSMISSILERANGE

i

Fig. 10. Sample locations for the San Antonio area.

area exceeding this level of plutonium is the controlledinner fenced area of GZ. The EPA has proposed ascreening level for no action of 200 nCi/m2, which isequivalent to about 15 pCi/g in the top 1-cm layer ofsoil. Measurements of 239-240Pu in controlled areas ofGZ exceed this proposed limit. Measurements made in1972 within 1 km of GZ in the fallout path exceed thislimit, but EPA measurements in 1973 and Los Alamosmeasurements in 1972 do not exceed the limits.

B. Cesium-137 in Soils

The amounts of 137Cs in soils of the GZ area exceedthe levels found in soils elsewhere in the U.S.26'27 How-ever, the amounts detected by in situ measurements onthe White Sands Missile Range and other fallout areasare within the range of values reported for the arealdistributions of worldwide fallout Table XX lists a rangeof 19 to 305 nCi/m2 from California to Connecticut. Ifthe measurements at San Antonio are assumed to belevels representing worldwide fallout, the White Sands

25

TABLE XIV

GROUND ZERO SURFACE MEASUREMENTS

Radionuciide

60Com C s152Eu

Natural gammaTotal gamma

4 0 K

2 3 2 T h

" 8U

2J9.24Opu

Inner fence, 0-1 cm1-6 cm0-15 cm15-30 cm30-45 cm

Between fences, 0-1 cm1-6 cm15-30 cm

Inner fence, 0-2.5 cmCombined, 0-5 cm

5-10 cm10-15 cm

137CsInner fence, 0-1 crn

1-6 cm0-15 cm15-30 cm30-45 cm

Between fences, 0-1 cm1-6 cm4-10 cm10-15 cm

N

666

66

666

11111

119

112333

111113333

Mean ± S.E."

5554 ± 3094 nCi/m2

8104 ±3772 nCi/m2

107 200 ± 54 400 nCi/m2

7.9 ±0.7 nR/h131 ±62 jiR/h

24 ± 4.4 pCi/g0.86 ± 0.03 pCi/g0.60 ±0.13 pCi/g

(1983) 22.8 ±0.2 pCi/g(1983) 156 ± 15 pCi/g(1983) 23.7 ± 0.4pCi/g(1983) 256 ± 3 pCi/g(1983) 0.4 ±0.02 pCi/g(1983) 5.8 ±9.5 pCi/g

(1983) 1.14 ±2.9 pCi/g(1983) 0.0053 ±0.003 pCi/g

(1972) 127 ± 180 pCi/g(1977) 31 ±31 pCi/g(1977) 34 ±30 pCi/g(1977 67 ± 116 pCi/g

16.5 ± 3.3 pCi/g21.8 ±4.4 pCi/g12.6 ±2.5 pCi/g21.5 ±4.3 pCi/g0.67 ±0.19 pCi/g0.54 ± 0.37 pCi/g0.64 ± 0.48 pCi/g0.33 ±0.12 pCi/g0.07 ±0.41

Min

0488842

5.59.8

120.780

b

b

b

b

b

b

0.040.020.0020.043.80.05

Radionuclide

TABLE XIV (cont)

Mean ± S.E."

"S.E. Standard Error.bSingle observation.

Min Max

152EuInner fence, 0-1 cm

1-6 cm0-15 cm15-30 cm30-45 cm76-91 cm106-122 cm

Between fences, 0-1 cm1-6 cm

112222288

284 ± 29 pCi/g245 ± 25 pCi/g382 ± 167 pCi/g

1013 ± 7 9 pCi/g225 ± 80 pCi/g

12 ± 16 pCi/g2.2 ± 2.4 pCi/g20 ± 18 pCi/g18 ± 14 PCi/g

b

b

264957169

0.50.43.43.5

b

b

5011069282

243.9

5946

Missile Range, Chupadera Mesa, and Far Fallout Zoneare 2.4, 4.2, and 2.2 times higher than levels expected incentral New Mexico.

Cesium also can be used as an indicator of the slowchanges in fallout distribution with time. Measurementsby the in situ detector on Chupadera Mesa were made fordifferent land forms at several locations. The ChupaderaMesa area has several closed drainage collection pointswhere the water and associated sediments from rainfallrunoff collect. Measurements were made on the slopesabove a collection point and on the sediment bed in thedry collection areas. Table XXI summarizes the datataken for such drainage systems on Chupadera Mesa.The arithmetic mean values for 137Cs on slopes abovedrainages and their associated collection points are notequal with a 99.5% confidence using Student's t-test forequal means. The data suggest that after 32 years thecesium bound to soils is slowly being transported intowater and sediment collection points. However, the proc-ess appears to be slow and any increased areal concentra-tion in the collection sediment points will be offset byradioactive decay with half of the activity disappearingevery 30.2 years.

C. Strontium-90 in Soils

Measurements of 90Sr in soils during the 1977 surveywere restricted to relatively few samples because ofanalytical costs. From the limited data, comparisons of

the 90Sr in soils of Chupadera Mesa and the Far FalloutZone with measurements of worldwide fallout in soils atvarious locations in the U.S. indicate a clear influencefrom the Trinity test. Table XXII summarizes data forlocations in mountain states of the U.S.; 90Sr levels in thefallout zone from the Trinity test range from 10 to 40times those both north and south of central New Mexico.

III. AIRBORNE RADIOACTIVE MATERIALS

Airborne radioactive materials measurements atTrinity site and in the fallout zone are extremely limited.During the 1973 and 1974 survey by the EPA, a 10-month air sampling was conducted on Chupadera Mesaand at Socorro, New Mexico, a community out of theinfluence of the Trinity test.13 Air concentrations ofplutonium at both locations were equal, but isotopicratios at Chupadera Mesa indicated the Trinity testplutonium contributed the major activity while worldwicefallout contributed the major activity at Socorro.13

Table XXIII includes plutonium concentrations in airsamples taken at GZ and at a control site 5.2 km south ofGZ in 1983. Also included are the air concentrationscalculate..' for resuspended plutonium (see Appendix Dfor details).

Comparison of the calculated resuspendsd plutoniumon Chupadera Mesa with the measured values indicatesthe calculations overestimate the actual amount by a

27

TABLE XV

WHITE SANDS MISSILE RANGE FALLOUT ZONE SCIL MEASUREMENTS

DepthRadionuclide

7Be60Co137CsI52Eu155Eu95Nb"Zr103Ru

Natural gammaTotal Gamma

4 0 K

2 3 8 U232 T h

238pu

239Pu (1948)"9Pu (1972)

(1972)(1972)(1973)

(1977)(1977)(1977)

90Sr

"7Cs

N

2222222222222222

2323

22—22

7......4444

13

767

443

121210

(cm)

—._...._________

...

...

...

0 - 55- 10

10- 150-2.50-2.5

2.2- 1010-300 - 5

0 - 55- 10

10- 15

0 - 55- 10

10- 15

0 - 55- 10

10- 15

Mean ± S.E.

5.7 ± 1.2 nCi/m2

27 ± 23 nCi/m1

162 ± 42 nCi/m2

77 ± 77 nCi/m5.5 ± 4.0 nCi/m2

3.1 ±0.26 nCi/m2

2.5 ± 0.27 nCi/m2

0.14 ±0.08 nCi/m2

7.8 ± 0.65 nR/h7.9 ± 0.56 nR/h

19 ± 1.4 pCi/g0.88 ± 0.05 pCi/g0.94 ± 0.08 pci/g

0.55 ± 0.43 pCi/g0.38 ± 0.38 pCi/g

0.009 ± 0.005 pCi/g1.32 ± 0.50 pCi/g

63 ± 63 pCi/g65 ± 65 pCi/g15 ± 15 pCi/g99 ± 84 nCi/m2

(1.42 pCi/g)10 ± 9 pCi/g

7.6 ± 7.3 pCi/g29 ± 29 pCi/g

1.8 ± 1.4 pCi/g0.38 ± 0.08 pCi/g0.70 ± 0.46 pCi/g

4.5 ± 2.3 pCi/g4.9 ± 2.6 pCi/g0.8 ± 0.7 pCi/g

Mm

TABLE XVI

BINGHAM AREA SOIL MEASUREMENTS, US HIGHWAY 380 CORRIDOR

DepthRadionuclide

1 Be60Co137Cs"NbNatural gammaTotal gamma40K21-Th- A 8 u23».24oPu (1948)

(1972)(1972)(1972)(1973)

N

222222222

2__.__.14

(cm)

...———.........___0- 1.50.-2.5

2.5 - 1010-300 - 5

Mean ± S.E."

5.8 ± 5.8 nCi/m2

0.6 ± 0.6 nCi/m2

52 ± 28 nCi/nr11.4 ±0.19 nCi/m2

5.6 ± 0.2 uR/h5.8 ±0.1 uR/h12 ±0.22 pCi/g

0.68 ± 0.035 pCi/g0.80 ±0.05 pCi/g

0.9 ± 0.4 pCi/g0.21 ±0.08 pCi/g0.43 ± 0.32 pCi/g

0.085 ± 0.085 pCi/g5.0 ± 3.3 nCi/m2/

(0.070 pCi/g)c

Min

TABLE XVII

CHUPADERA MESA SURFACE SOIL MEASUREMENTS

Radionuclide

'BewCom C s'"Euc

'"Eu"Nb"Zr"»Ru

Natural gammaTotal gamma

« K!):Th" ! U

"»Pu

; " ! 4 0 Pu

'°Sr

'"Cs

i(1948)(1950)(1972)(1972)(1972)(1973)

(1977)(1977)(19771(1977)

N

4949494949494949

4949

494949

1915153

109

33

1914

163

7

3

274

161

Depth(cm)

0-5 .

10-15-

5101520

0.-2.5

0-0-

2.5-

10-0

05 -

10-15

010

05

1020

2.52.510305

5101520

-5- 15

. 5

• 10

- 15• 2 5

Mean ± S.E.'

8.8 ± 1.1 nCi/rrr0.58 ± 0.16 nCi/m :

280 ± 30 nCi/m!

0.48 ± 0.48 nCi/nr4.2 ± 2.4 nCi/m :

4.65 i 0.15 nCi/m1

2.55 ±0.15 nCi/nr0.28 ± 0.07 nCi/m :

6.7 ± 0.24 nR/h8.2 ± 0.32 MR/h

16 ± 0.58 pCi/g0.85 ± 0.04 pCi'g0.88 ± 0.04 pCi/g

0.083 ± 0.020 pCi/g0.023 ± 0.013 pCi/g0.006 ± 0.004 pCi/g0.003 ± 0.003 pCi/g

3.1 ± 1.3 pCi/g3.2 ± 1.2 pCi/g

0.80 ± 0.34 PCi/g0.15 ±0 .10 pCi/g

0.033 ± 0.015 pCi/g20.6 ± 4.3 nCi/m2

(0.29 pCi/g)d

1.7 ±0.41 pCi/g0.38 ± 0.2" pCi/g0.11 ± 0.07 pCi/g

0.033 ± 0.03 pCi/g

2.3 ± 1.0 pCi/g0.76 ± 0.47 pCi/g

2.81 ±0.52 pCi/g0.16 ± 0.02 pCi/g0.04 ± 0.02 pCi/g0.05

Min

TABLE XVIII

FAR FALLOUT ZONE SURFACE SOIL MEASUREMENTS

Radionuclide

7Be60Co137Cs" N b95Zr103Ru

Natural gammaTotal gamma

«oK232 T h

238U

» 8 P u

239,24Opu

(1950)(1973)

(1977)

90Sr

137Cs

N

272727272727

2626

272727

1286

18

24

1498

4111

1054

Depth(cm)

——

—

...

...

...

0 - 5

5 - 1010-15

0-2.50-2 .50 - 5

0 - 55 - 10

10- 15

0 - 55 - 10

10- 1520-25

0 - 55-10

10- 15

Mean ± S.E."

12 ± 1.2 nCi/m2

0.82 ±0.61 nCi/m2

152 ±34 nCi/m2

4.5 ± 0.29 nCi/nr2.9 ± 0.24 nCi/m2

0.25 ±0.10 nCi/m2

8.3 ± 0.53 nR/h8.9 ± 0.55 uR/h

19 ± 1.1 pCi/g1.20 ±0.12 pCi/g0.94 ± 0.05 pCi/g

0.018 ±0.005 pCi/g0.008 ± 0.005 pCi/g

TABLE XIX

SAN ANTONIO AREA SURFACE SOIL MEASUREMENTS

Radionuclide

7Be60Col37Cs93Nb"Zr

Natural gammaTotal gamma

4 0 K

2J2Th2J8U

239.24Opu

239,240pu

239,240pu

N

99999

99

990

444

Depth(cm)

———...

—

——

0-55- 10

10-15

Mean ± S.E.fl

3.9 ± 2.0 nCi/m2

9.7 ± 6.0 nCi/m2

67 ± 20 nCi/m2

2.0 ±0.3 nCi/m2

1.5 ± 0.33 nCi/m2

7.5 ± 0.6 uR 'h7.7 ± 0.5 uR/h

15 ± 1.4 pCi/g0.83 ±0.12 pCi/g

1.2 ±0.13 pCi/g

0.01 ±0.004 pCi/g0.003 ± 0.003 pCi/g

TABLE XX

AREAL CONCENTRATIONS OF 157Cs

Location

Trinity Fallout AreasWS.MRBinghamChupadera MesaFar Fallout Zone

Central NMSan Antonio

Other Areas of U.S.Amarillo, TX°Burlington, 1A°Diablo Canyon, CAC

Humboldt Bay, CAC

San Clemente, CAC

La Crosse, WTBaxley, GAC

Daisey, TNC

Waterford. CNC

Mean(nCi/m2)

8104 ± 377252 ± 18

280 ± 30152 ± 34

67 ±20

148 ± 32105 ± 341053219

13960

168305

Min

488343010

TABLE XXI

CHUPADERA MESA IN SITU 137Cs DATA FOR SOILSBY LAND FORM (nCi/m2)

Location

Cuate Tank

Three Peaks Area

Area 21

High Point on Mesa

SlopeAbove Drainage

388—

261314

—338428308428602

X s = 383S.E. = 38

H: X st = -

Closed DrainageCollection Point

756547947410590545512

...—

540XD = 605S.E. = 59

= x D3.16

True: % of time

34

TABLE XXII

90Sr BACKGROUND INFORMATION

Location

DenverSalt Lake CityE! PasoHoustonDallasChupadera Mesa

Far Fallout Zone

FalloutCone 90Sr(uCi/m2)

41.2191.6115.5536.4040.24688to334

1959-1976Rainfall

(cm)

692.73801.87335.15

2186.861300.49365

to914

Latitude andLongitude

39°46'40°46'31°48'29°39'32°51'33°4O'

to34°20'

1O4°53'110°49'106°48'95°17'96°51'

1O5°4O'to

106° 30'

Altitude(m)

161115161204

22160

1524to

2450

35

TABLE XXIII

POTENTIAL CONTRIBUTIONS OF RESUSPENSIONTO 239Pu AIRBORNE RADIOACTIVITY

Measured Airborne239Pu Concentrations

Chupadera Mesa (10 months)b

Soccorro (10 months)b

GZ AverageCenter (28.7 h)b

Mid-radius (29.8 h)b

Entrance (34.8 h)b

Control Site WSMR (37.9 h)b

239pu

Concentration(aCl/m3)

4341

6331.21.1

Per CentDOE

ConcentrationGuide

0.00430.0041

0.00630.00030.000120.00011

Per Cent ofProposed EPADerived Limit"

4.34.1

6.30.30.10.1

Calculated Contributions ofResuspension to 239PuAirborne Concentrations

GZWhite Sands Fallout AreaBinghamChupadera MesaFar Fallout Zone

Range of 239Pu from WorldwideFallout, 1974-1978, at Santa Fe, NM

Low (1976)5-Year AverageHigh (1978)

"See Table XXVI.bSample time.

3822

712022

0.00380.00220.00070.0120.0022

3.82.20.7

122.2

3.81624

0.0060.030.04

0.41.62.4

36

TABLE XXIV

EXTERNAL RADIATION EXPOSURE SUMMARY FOR IN SITU DATA

White Sands South of GZ(Los Alamos National Labora-tory Control) 3 Miles South

GZ

White Sands Missile Range inFallout Path

Chupadera Mesa, Area 21, Los AlamosNational Laboratory Study Area30 miles from GZ)

Monte Puerto Ranch

Far Fallout Zone (~55 miles NE from GZ)

Due to NaturalTotal External

Due to NaturalTotal External137Cs132Eu

Due to NaturalTotal External137Cs

Others: M Co, 152Eu, 134Eu

9.3 ±9.8 ±

5.6 ±175 ±9.9 ±137 ±

8.1 ±22 ±1.8 ±13.1

0.17 uR/h0.23 uR/h

0.5 uR/h1.1 uR/h0.15 uR/h0.7 uR/h

0.26 uR/h0.3 jiR/h0.03 uR/huR/h

Due to NaturalTotal External137Cs

Due to NaturalTotal External137Cs

Due to NaturalTotal External

6.0 ±0.14 uR/h8.1 ±0.14 uR/h2.0 ±0.03 uR/h

8.2 ±0.13 uR/h9.8 ±0.14 fiR/h1.5 ± 0.02 uR/h

6.8 ±0.28 uR/h7.5 ± 0.28 uR/h

37

TABLE XXV

EXTERNAL PENETRATING RADIATION MEASUREMENTSAND ESTIMATES OF CONTRIBUTIONS FROM TRINITY FALLOUT

(urem/h)

Estimated ContributionLocation Measurement Above Background

GZCenter MaximumInner FenceOuter Fence

White Sands Missile Range

Bingham

Chupadera Mesa

Far Fallout Zone

485 ± 4205 ± 6110.8 ± 2.5

7.8 ± 0.6

5.8 ±0 .1

8.2 ± 0.32

8.9 ± 0.55

477187

3.1

0.1

0.2

1.5

0.6

38

on-i2

• CONTROL SITE3 MILES WEST7.1 1

•0

••

A

LEGEND

AUGER SAMPLES

SPLIT SPOON SAMPLES

AIR SAMPLER

METEOROLOGICAL TRAILER

TLD LOCATIONS

k J 9.8 ± Z^R/hr

\

SOUTH OATE

D 2O0

3 M

•100

100 150 2 0 0

8 0 0

no

A CONTROL SITE3 MILES SOUTH

2 P / l

Fig. 11. External radiation dose rates measured at Trinity Site, June 9,1983 to June 23,1983.

39

5. POTENTIAL DOSE EVALUATION AND INTERPRETATION

The significance of the data on concentrations ofradioactivity on soils and sediments, radioactivity onairborne particulates, and external penetrating radiationmay be evaluated in terms of the doses that can bereceived by people exposed to the conditions. The dosescan be compared with natural background and ap-propriate standards or guides for one type of perspective.The doses can also be used to estimate risks orprobabilities of health effects to an individual, providinganother type of perspective more readily compared withother risks encountered. This section summarizes theanalysis of potential doses and risk estimates. The de-tailed analysis is presented in Appendix D. Readersdesiring more information on concepts of radioactivity,radiation, and dose interpretation may be helped byAppendix E, Evaluation of Radiation Exposures.

I. BASES OF DOSE ESTIMATES AND COMPARISONS

Doses were calculated for various pathways that couldresult in the inhalation or ingestion of radioactivity. Thecalculations were based on theoretica