ANL-6024 Reactors - General (TID-4500, 15th Ed.) AEC Research and Development Report

ARGONNE NATIONAL LABORATORY P . O. Box 299

Lemont, Illinois

DESIGN AND HAZARDS REPORT FOR THE

ARGONNE FAST SOURCE REACTOR (AFSR)

by

G. S. Brunson Idaho Division

Contr ibutors

R. N. Cur ran R. O. Haroldsen D. C. Jacobson F . S. Kirn R. L. McVean R. E, Rice F . W. Thalgott M. B. Tr i l lhaase

June, 1959

Operated by The Universi ty of Chicagc under, , - i

Contract W-31-'eng-38

DISCLAIMER

This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency Thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.

DISCLAIMER Portions of this document may be illegible in electronic image products. Images are produced from the best available original document.

T A B L E O F C O N T E N T S

P a g e

ABSTRACT 7

INTRODUCTION 8

SECTION I 10

R e a c t o r D e s c r i p t i o n 10

C o r e 10

B lanke t 11 Sou rce 12 R e a c t o r Layou t 12 Shie lding 12 T h e r m a l Co lumn 13 S u b - R e a c t o r P i t 13 Cool ing S y s t e m 13

R e a c t o r C o n t r o l 14

Safety Rods 14 Safety P lug 15 C o n t r o l Rod 1 6 Sh im R o d s 16 C o n t r o l C i r c u i t s 16 S c r a m I n t e r l o c k 17 S t a r t u p I n t e r l o c k 18 S t a r t u p Sequence 18 A l a r m I n t e r l o c k 18

R e a c t o r I n s t r u m e n t a t i o n 18

R e a c t o r P h y s i c s 19

R e a c t o r Bui ld ing 21

Site 21

SECTION n 23

M a n a g e m e n t of the R e a c t o r 23

Staff 23 Ini t ia l S t a r t u p 23 O p e r a t i o n 24

T A B L E O F C O N T E N T S

P a g e

SECTION n i 25

H a z a r d s 25

G e n e r a l 25 Method of C a l c u l a t i o n 26 T y p e s of Inc ident C o n s i d e r e d 28 H a z a r d s in R e t r i e v i n g F o i l s 30 M i s c e l l a n e o u s H a z a r d s 30

CONCLUSION 31

BIBLIOGRAPHY 32

A P P E N D I X I LOADING E R R O R WITH MACHINE F A I L U R E 33

A P P E N D I X n E R R O R OR MISHAP IN O P E R A T I O N 39

LIST OF FIGURES

Title Page

Core Assembly 41

Blanket and Core Assembl ies 42

Cutaway View of Argonne Fas t Source Reactor 43

Reactor and Thermal Column 44

Reactor Pit Layout 45

Safety Rod Drive Assembly 46

Safety Rod Per formance Curve 47

Pneumatic System 48

Safety Plug Per formance Curve 49

Two Speed Jack Assembly 5 0

Control Rod Drive Assembly 51

Shim Rod Actuator Assembly 5 2

Control Console 5 3

Control Panel 54

Instrumentation 55

Plot Plan 56

Reactor Bldg. Layout 5 7

National Reactor Testing Station Map 5 8

Central Fac i l i t i es 20 Foot Level Wind Rose 1950

Through 1956 59

Beam Hole Liner 60

Predicted Behavior of AFSR Going Cri t ical 0.1 inch from Fully Assembled Posit ion at a Rate of 0.0004 Ak/k per Second 6I Predic ted Behavior of AFSR Going Cri t ical 0.3 inch from Fully Assembled Posi t ion at a Rate of 0.0004 Ak/k per Second 62

Predicted Behavior of AFSR Going Cri t ical 0.1 inch fronn Fully Assembled Posit ion at a Rate of 0.003 Ak/k per Second 63

LIST OF FIGURES

Title Page

Predic ted Behavior of AFSR Going Cri t ical 0.3 inch froin Fully Assembled Posi t ion at a Rate of 0.003 Ak/k per Second 64

Predic ted Behavior of AFSR Going Cri t ical 1 inch fronn Ful ly Assembled Posit ion at a Rate of 0.03 Ak/k per Second 65

LIST OF TABLES

Title Page

Summary of Design Charac te r i s t i c s 9

Reactivity Effects 20

Summary of Excurs ions Studied 26

Probable Maximum Doses from Radiation Cloud 38

o

DESIGN AND HAZARDS REPORT FOR THE

ARGONNE FAST SOURCE REACTOR (AFSR)

G. S. Brunson

ABSTRACT

The Argonne Fas t Source Reactor is designed to operate at low power (nominally 1000 watts) to supply neutron fluxes, both fast and the r ­ma l , for l abora tory exper iments . It is built around a-cylindrical core (with ver t ical axis) of solid, highly enriched uranium approximately 42 inches in d iameter by 4:^ inches high. The blanket is of solid depleted uranium with a minimum thickness of eight inches; i ts outer form is cylindrical , 20^ inches in d iameter by 20-| inches high. The reac tor , contained in a shield of high density concrete of minimum thickess 4-2 feet, is f reestand­ing on the floor of the r eac to r building. A graphite thermal column 4 x 4 x 6 feet is provided. All control and safety mechanisms are located in a pit beneath the r eac to r .

The hazards associa ted with operation of the reac tor have been analyzed. A number of potentially dangerous c i rcumstances were studied to determine the probable sever i ty of the resul tant excurs ions . As an up­per l imit , a detailed study was made of the extreme case in which the r e ­actor , overloaded by five k i lograms of U^^ , goes cr i t ica l at the air cylinder speed of 18 inches per minute . It is es t imated that the excursion would amount to 3.6 x 10^^ f iss ions . This is expected to des t roy the core and eject all core ma te r i a l into the pit where it bu rns , great ly adding to the total energy of the excurs ion. No rupture of reac tor shield or building is expected. The reac to r pit and reac to r building will be heavily contaminated and some radioactive miaterial will escape from the building. It is near ly cer ta in that the maximum radiat ion dose to personnel outside the reac tor building will not exceed 15 roentgens .

Considerat ion of the design cha rac t e r i s t i c s , possible accidents and method of operat ion lead to the conclusion that the reac tor is fundamentally safe for the following r ea sons :

1. The t empera tu re coefficient of react ivi ty is substantially negat ive.

2. The policy of operation with a fixed loading of l imited excess react iv i ty leaves li t t le opportunity for dangerous personnel e r r o r .

3. The inter lock system and sc ram instrumentat ion are such that a very improbable number of simultaneous fai lures must occur if a personnel e r r o r is to resu l t in a significant excursion.

4. Both core and blanket a re at maximum density; a lmost any conceivable dis turbance reduces react ivi ty .

5. Even in the event of a severe excursion, the isolation of the si te , the prevail ing winds, and the low inventory of fission products minimize the number of pe rsons exposed and the sever i ty of their exposure .

INTRODUCTION

The Argonne Fas t Source Reactor (AFSR) is designed as a l abora ­to ry tool to augment the r e s e a r c h capability of the Idaho Division, Argonne National Labora tory . It will, without interfering with p rog rams of existing r e a c t o r s , supply stable, reproducible fluxes of both the rmal and fast neu­t r o n s . The reac tor will be used in var ious ways:

1. To tes t neutron de tec tors in development and to cal ibrate operational counters for use in other r e a c t o r s .

2. To i r r ad ia t e foils for the development of advanced foil counting and radiochemical techniques.

3. To check out complex experimental sys tems ahead of t ime in o rder to avoid waste of ZPR-III or other exper imental reac tor t ime .

4. To supply fluxes in which can be tes ted equipment for advanced exper iments such a s :

a. Measurement of fast neutron spect ra b . Measurement of s ta t is t ical fluctuations of reac to r neutron

populations.

The design chosen is expected to accomplish the foregoing economi­cally in t e r m s of both cost and manpower.

Reactor cha rac t e r i s t i c s a re summar ized in Table I.

Table I

SUMMARY OF DESIGN CHARACTERISTICS ARGONNE FAST SOURCE REACTOR

Core

Geometry - solid right c i r cu la r cylinder Diameter of uranium, inches including

0.005 inch nickel can Length, inches including 0.005 inch

nickel can Mater ial Criticcd m a s s U^^ , kg

4.50

-4 .25 Uranium, highly enriched -20 kg

Blanket

Geometry - hollow right c i rcu la r cylinder Outside d iameter and height, inches Thickness , inches Mater ial Mass U"8 (0.2% U"5)

20 I 8 Depleted Uranium 2100 kg

Reactor Cooling Systein

Design reac tor power, watts Cooling a i r flow, cfm P r e s s u r e drop a c r o s s core and blanket, psi Air t empera tu re r i se a c r o s s core , °C Maximum meta l t e m p e r a t u r e , °C Percentage of power produced in core Percentage of power produced in blanket

1000 55 6 20 98 80 20

Nuclear

Neutron energy Maximum neutron flux, n / c m - sec Central fission ra t io , U^^^ to U"^ Prompt neutron lifetime Reactivity Worth:

Control rod, Ak/k Safety and shim rods (each) Fuel at radial edge of co re , per mole

Effective delayed neutron fraction

Fas t 5.7 X 10^^ .14 2 X 10"^ sec

.00313 Ak/k (46/)

.00662 Ak /k (97/)

.00532 Ak /k (78/)

.0068

Biological Shield

Mater ial

Nominal th ickness , ft

Magnetite aggregate concrete , (215 lb/ft ' )

4i

SECTION I

THE ARGONNE FAST SOURCE REACTOR

A. Reactor Descript ion

1. Core

The core of the Argonne F a s t Source Reactor is a right c i rcu la r cylinder of highly enr iched uranium, 4.50 inches in d iameter and approximately 4.25 inches high. The es t imated cr i t ica l m a s s is 20 kilo­g rams . As shown in F igure 1, the core is composed of uranium discs canned in .005 inches nickel to prevent oxidation. The discs a re aligned and held in place by s ta inless steel cages .

The core is divided into two sect ions. The upper section constitutes about 3/5 of the c r i t i ca l ma te r i a l and has a fixed position and loading. It consis ts of two uranium discs separa te ly canned and held in position by the upper cage. There is a horizontal l / 2 inch diameter "glory hole" at the approximate reac tor center l ine.

The glory hole is lined with a 5 mil thick nickel tube which is welded at its ends to the nickel can. Surrounding this nickel l iner is a tube of zirconium with walls of 10 mil th ickness . The purpose of the z i r ­conium is to separa te the uranium from the nickel l iner so that in a ser ious excursion formation of a uranium-nickel eutectic will not occur at the center of the core . Otherwise, molten ma te r i a l might collapse into the glory hole, ser ious ly increasing the available react ivi ty.

The lower 2/5 of the core and the supporting blanket section to which it is at tached compr ise the safety plug which can be r a i sed and lowered by means of an a i r cylinder. The lower core section is composed of discs of var ious th icknesses so that the core loading can be var ied. These discs a r e attached to the supporting blanket section by means of a second s ta inless steel cage. The topmost disc has a r e c e s s about l - l / 4 inches in d iameter by 5/32 inch deep for i r rad ia t ing foils.

The top disc of the lower section and the two discs of the upper section aggregate about 15 k i lograms of fuel. The cr i t ica l m a s s will be attained stepwise by adding and subtract ing conabinations of the following available d i scs .

Number of Discs Thickness Weight each (inches) (kilograms)

5

2

2

0.300

0.150

0.050

1.47

.73

.24

After the exact c r i t i ca l m a s s has been obtained, the discs re­quired in the lower core section to obtain cr i t ical i ty will be canned in a single can of 5 mil nickel. In addition, there is a shim disc of uranium 0.100 inches thick canned in nickel; this can be added to the lower core section for a la rge react ivi ty increment . Continuous shimming of r e ­activity over a wide range is obtained from two blanket shim rods to be descr ibed la te r .

2. Blanket

The blanket or ref lector (Figure 2) of the Argonne F a s t Source Reactor consis ts of a s tack of five rings and top and bottom plugs of de­pleted uranium which form a hollow right c i rcular cylinder 20-5 /8 inches outer d iameter by 20-5 /8 inches high. The walls a r e 8 inches thick leaving a cavity approximately 4 -5 /8 inches by 4 -1 /2 inches which is large enough to provide an annulus for cooling air between core and blanket. The cavity is lined with 20 mil s ta in less steel to prevent oxidation.

The five blanket rings a re dri l led for ver t ica l tie rods which provide orientation and rigidity. The center blanket ring which immedi ­ately surrounds the core is cut in three pie-shaped sections to reduce the tamping effect in the event of a severe excursion. The reactor assembly (except safety plug) is supported by a one inch steel plate and held in place by the tie rods . The safety plug is bolted to a flange on the end of the a i r cylinder shaft. Both top and bottom blanket plugs a re p ierced by 3/4 inch holes which allow a i r to be c i rculated through the cooling annulus.

Four ver t ica l 2 - l / l 6 inch holes in the blanket a re centered on a radius of 3 - 9 / l 6 inches from the axis of the reac tor . Two holes a re for safety rods and two a r e for shim rods ; all a re lined with 20 mil s ta in less steel s leeves . The one-inch control rod operates in a ver t ical blanket hole located on a radius 3 - l / l 6 inches from the reac tor axis . The axis of the one-inch diameter horizontal source hole is radial to the axis of the r eac to r and l ies 2 -7 /8 inches above the horizontal midplane. The inner end of the source hole is about 3.8 inches from the core axis .

There a re three exper imental holes in the blanket. The 1/2-inch diameter "glory hole" , located on the horizontal centerl ine of the

core and blanket, is a continuation of the one through the core . The ap­proximately 2 -1 /4 inch d iameter radial beam hole t e rmina tes l / 2 inch from the inner edge of the blanket. The centerl ine of the I - I / I 6 inch grazing hole pas ses I - I / 2 inches from the inner edge of the blanket at the closest point. Access to all exper imental holes is by means of stepped plugs in the shield.

3. Source

A 15-curie polonium-beryl l ium neutron source is located in the blanket at the position shown in F igure 2. The source may be manually r e t r ac ted into the shield by means of a mechanical dr ive. Limit switches at the "in" and "out" positions operate the source interlock and indicator lights on the control console.

4. Reactor Layout

The general a r rangement of the reac to r , shield, thermal column, sub- reac to r pit, exper imental and ins t rument holes , etc. is shown in F igures 3 and 4. All safety and control drive mechanisms a re located in the pit and all r eac to r load changes a r e nnade the re .

Fo r operating convenience the horizontal centerl ine of the reac tor core , blanket and the rmal column is located 36 inches above the f loor- l ine. The reac tor support plate is c a r r i e d on a machined support ring which is cast into the concrete shield. The ver t ica l hole in the shield for receiving the reac to r is 24-5 /8 inches in d iameter leaving an annulus of two inches between blanket and shield. A th ree- inch space is a lso p r o ­vided between the top of the blanket and the bottom of the top shield plug.

5. Shielding

The reac tor biological shield, shown in F igu re s 3 and 4 is composed of magnetite aggregate concrete with a density of 215 pounds per cubic foot. The nominal shielding thickness is 4 - l / 2 feet around and above the reac to r . The thermal column shielding plate is 1" steel faced with 1/8 inch of bora l . Since the sub- reac to r pit will not be occupied during operation, the region below the reac tor is only par t ia l ly shielded. A minimum of two feet of magneti te concrete or its equivalent in ordinary concrete and ear th is provided between the pit and the floor outside the shield to absorb neutrons sca t te red off the pit floor. All experimental and ins t rument holes through the shield a r e provided with stepped plugs. The inlet duct for r eac to r cooling a i r which penetrated the shield has an offset.

6. T h e r m a l C o l u m n

The t h e r m a l c o l u m n , shown in F i g u r e s 3 and 4 , i s four fee t wide by four feet h igh by s i x fee t long f r o m b l anke t edge to end. It is bu i l t up of four inch by four inch s q u a r e b a r s of r e a c t o r g r a d e g r a p h i t e . The four c e n t e r long i tud ina l g r a p h i t e s t r i n g e r s in the t h e r m a l co lumn a r e r e m o v a b l e for e x p e r i m e n t a l p u r p o s e s . T h e r e a r e two 2 - inch d i a m e t e r h o r i z o n t a l h o l e s t h r o u g h the g r a p h i t e , one is two feet and a n o t h e r four fee t f r o m the r e a c t o r c e n t e r l i n e .

7. S u b - R e a c t o r P i t

The s u b - r e a c t o r pi t , shown in F i g u r e s 3 and 5 is l o c a t e d b e ­low the r e a c t o r and sh i e ld . In t h i s pit wi l l be l o c a t e d the m e c h a n i s m s for safe ty r o d s , sa fe ty p lug , c o n t r o l r o d and s h i m rods and the l ead sh i e ld for r e l o a d i n g . P e r s o n n e l a c c e s s to the pit is v ia a 30 x 36 - inch r e c t a n g u l a r m a n h o l e in the f loor ou t s ide the s h i e l d and a tunnel t h r e e feet wide and s i x fee t h igh b e n e a t h the f loor and sh i e ld . The w a l l s of the pi t , m a d e of o r d i n a r y c o n c r e t e , s e r v e a s p a r t of the r e a c t o r b io log ica l sh ie ld foundat ion. The ce i l i ng is a o n e - i n c h th i ck s t e e l p l a t e u s e d for moun t ing m e c h a n i s m s .

8. Cool ing S y s t e m

To a c h i e v e a 1000 wat t c a p a c i t y , an induced draf t a i r cool ing s y s t e m is i n c o r p o r a t e d in t h i s d e s i g n . As shown in F i g u r e s 4, 2 and 1, it h a s the fol lowing flow pa th : a i r e n t e r s t h r o u g h an inlet f i l t e r on the s ide of the b i o l o g i c a l s h i e l d and p a s s e s t h r o u g h an offset duct to the top of the a n n u l a r cav i ty b e t w e e n s h i e l d and b lanke t . The a i r f lows down a r o u n d the b l anke t to a duct cut into the suppor t p l a t e and safe ty plug f lange . The a i r t hen f lows up t h r o u g h a 3 / 4 - i n c h d i a m e t e r hole in the sa fe ty p lug , into a l / 8 - i n c h t h i c k ax i a l s p a c e below the c o r e , a r o u n d the c o r e in an a n n u l a r p a s s a g e l / l 6 - inch th ick , into a l / 8 - i n c h ax i a l s p a c e above the c o r e and out the top b l anke t plug in a n o t h e r 3 / 4 - i n c h d i a m e t e r ho le .

F r o m the top of the b l a n k e t a duct r u n s down and u n d e r the f loor to the b l o w e r pit w h e r e the a i r p a s s e s t h rough a CWS type abso lu t e f i l t e r b e f o r e e n t e r i n g the p o s i t i v e d i s p l a c e m e n t type b l o w e r . F r o m the b l o w e r d i s c h a r g e a 2 - l / 2 inch d i a m e t e r exhaus t r u n s b e n e a t h the f loor to a muf f l e r , flow m e a s u r i n g o r i f i c e , and s t a c k a t t a c h e d to the s ide of the Lui lding. The s t a c k d i s c h a r g e s t e n feet above the roof peak .

In add i t ion , a s e p a r a t e s y s t e m p r o v i d e s ven t i l a t i on to the s u b -r e a c t o r pit and b l o w e r p i t . A i r is d r a w n th rough an in take in the s ide of the bu i ld ing , t h r o u g h the r e a c t o r pit u n d e r the f loor t h rough a f i l t e r in the b l o w e r pi t , t h r o u g h the b l o w e r pit i tself , and is e x h a u s t e d t h r o u g h a

separa te stack by a wall-mounted blower ra ted at 280 cfm at 2 - l / 4 inches static p r e s s u r e . The sys tem removes the heat generated in the blower pit by the reac tor cooling blower. It provides ventilation for the sub-reac tor pit so that build-up of radioactivi ty is minimized and activated dust is collected on the sys tem fi l ter .

A steel mockup of the air path through the blanket and around an e lec t r ica l ly heated core was used to determine the following design cha rac t e r i s t i c s at a power of 1000 wat ts :

Flow 55 cfnn

P r e s s u r e Drop (Across core and blanket) 6 psi

Air t empera tu re r i s e 20°C

Metal t empera tu re l / 8 " inside core surface 56°C above ambient

Centra l Metal t empera tu re (Extrapolated to center of uranium core from above s teel core data) 78°C above ambient

B. Reactor Control

1. Four types of control e lements a re used in the F a s t Source Reactor :

a. Two safety rods which decrease react ivi ty through removal of blanket ma te r i a l .

b. The safety plug which affects react ivi ty by the move­ment of core and blanket ma te r i a l .

c. The control rod gives fine control of react ivi ty through movement of blanket ma te r i a l .

d. Two shim rods physically identical to the safety rods can be adjusted manually only from the sub- reac to r pit to compensate for react ivi ty effects of loading.

2. Safety Rods

The two safety rods , located in the blanket, as shown in F igure 2, a r e 2-inch d iameter by 13-1/4 inches long cyl inders of de­pleted uranium with a s t roke of six inches. Each rod is connected by an extension shaft through a hole in the lower shield to the rack of the safety rod drive mechanism mounted on the sub- reac to r pit ceiling.

This m e c h a n i s n n , shown in F i g u r e 6, is a mod i f i ca t ion of the Z P R - I I I S a f e t y - C o n t r o l Rod D r i v e . It c o n s i s t s of a r a c k and pinion d r i v e n t h rough a D.C. m a g n e t i c c lu t ch by a g e a r h e a d m o t o r with m a g n e t i c b r a k e . A t t a c h e d to the l o w e r end of the r a c k is the p i s ton shaft of a 2 - inch d i a m e t e r pneu­m a t i c c y l i n d e r which i s p r e s s u r i z e d to 125 ps i on the uppe r s ide of the p i s ton . Unde r n o r m a l o p e r a t i o n , the m o t o r d r i v e s the safety r o d at a speed of 4 i n c h e s p e r m i n u t e . On a s c r a m s igna l the m a g n e t i c c lu tch is d e - e n e r g i z e d and the r o d is f i r e d out by the p n e u m a t i c cy l i nde r unt i l s topped by the dash pot at the end of i t s s t r o k e . A .25 cubic foot c apac i t y a c c u m u l a t o r tank s t o r e s high p r e s s u r e a i r for both safe ty rod m e c h a n i s m s . A check va lve in the in le t l ine p r e v e n t s l o s s of a i r in the tank in the event of supply a i r f a i l u r e . A d r o p in a c c u m u l a t o r p r e s s u r e be low 100 ps i c a u s e s s c r a m . A low b a c k p r e s s u r e r e g u l a t e d at 15 p s i ( see F i g u r e 8) is supp l i ed to a s s i s t in d e c e l e r a t i n g a t the end of the s t r o k e . F i g u r e 7 is a s c r a m p e r f o r m a n c e c u r v e for the sa fe ty rod m e c h a n i s m .

3. Safety P lug

The sa fe ty plug i s a c t u a t e d by a p n e u m a t i c cy l inde r of 4 - inch d i a m e t e r and 4 3 - i n c h s t r o k e , wi th a long cush ion d a s h pot, which is loca ted in a we l l in the pit a s shown in F i g u r e 5. Air to the cy l inde r i s c o n t r o l l e d by so leno id v a l v e s a s shown in F i g u r e 8. To i n s e r t the safety plug, a i r f rom a p r e s s u r e r e g u l a t o r i s b led t h r o u g h a 5-foot length of l / l 6 in. I .D. tubing and t h r o u g h a s econd p r e s s u r e r e g u l a t o r to the lower end of the a i r cy l inde r The p r e s s u r e r e g u l a t o r input to the s m a l l bo re tube i s ad jus ted (to 40 ps i ) so tha t the a i r flow wil l c a u s e the cy l i nde r 1^ t r a v e l at 18 i n c h e s / m i n u t e . Th i s r e g u l a t o r is s e c u r e d by key lock a g a i n s t t a m p e r i n g . The second r e g u ­l a t o r , which fol lows the s m a l l b o r e tube , is se t at about 20 ps i so tha t the s t a t i c p r e s s u r e wi l l not r i s e h igh enough to d a m a g e the a r m which engs -es the j ack . It i s b a c k e d up by two r e l i e f v a l v e s . When the safe ty plug i s s ix i n c h e s f rom i t s " u p " pos i t ion , an a r m on the a i r cy l inde r shaft engages the lower end of a m e c h a n i c a l j ack . The j ack ( F i g u r e 9) is then backed off a t a s p e e d of 2 i n / m i n unt i l it is l - l / 4 i n c h e s f rom the "up" pos i t ion; t h e r e a f t e r , it m o v e s a t l / 4 i n / m i n un t i l fully " u p . " The cy l inde r a i r p r e s s u r e f o r c e s the plug to follow the j ack . The d e s i g n of the j a c k i s u n u s u a l in tha t it changes the speed at which the plug r i s e s wi thout change of g e a r r a t i o s or r e c o u r s e to s e p a r a t e e l e c t r i c m o t o r s a c t u a t e d by l i m i t swi t ches at the changeove r point . Th i s added r e l i a b i l i t y i s a t t a i n e d by us ing a s ingle g e a r t r a i n to d r i v e two s e p a r a t e s c r e w s : the ou t e r (low speed) s c r e w , and i nne r , n o n - r o t a t i n g ( i n t e r m e d i a t e speed) s c r e w . The s p e e d change is a c c o m p l i s h e d by so a d j u s t ­ing the dev i ce tha t the sa fe ty plug follows the inner s c r e w f rom 6 inch to 1 - 1/4 inch s e p a r a t i o n a t which point con tac t is shif ted to the s low mo t ion ou t e r s c r e w which the sa fe ty plug then follows to the fully a s s e m b l e d pos i t ion .

For slow shutdown the low p r e s s u r e air supply valve is shut off and the lower end of the a i r cylinder is vented to the air so that the plug descends under its own weight. On a s c r a m signal solenoid valves a re de-energized to admit high p r e s s u r e (125 psi) a i r to the cylinder above the piston s imultaneously venting the cylinder below the piston, and firing the safety plug downward. F igure 8a gives the safety plug s c r a m performance curve . The jack automatical ly runs out to meet interlock requ i rements for next s tar tup. A separa te accumulator tank of 2-1/2 cubic foot capacity s to res a i r for the safety plug cylinder alone. A p r e s s u r e switch s c r a m s the reac to r in the event a i r p r e s s u r e falls below 100 psi in the accumulator for the safety plug.

4. Control Rod

The control rod is a one-inch dianneter by 12-1/4 inches long cylinder of depleted uranium. It is located in the blanket, as shown in Figure 2. It has a stroke of six inches, a speed of three inches a minute, and does not s c r a m . The control rod is connected by an extension shaft through the lower shield to a lead screw and nut mechanism mounted on the pit ceiling, as shown in F igure 10. A gear head motor with magnetic brake dr ives the lead screw. The position indicator synchro is geared off the lead screw.

5. Shim Rods

The two shim rods a re physically the same as the safety rods , but a re operated manually by a nut and screw mechanism (Figure 11). They can be operated only from the pit when the reac tor is shut down. Their single drive can be locked by key to prevent tamper ing or un­authorized movement. The purpose of these rods is to provide latitude of react ivi ty adjustment to compensate for changes caused by exper iments in the access holes.

6. Control Circui ts

The Argonne Fas t Source Reactor is controlled from a console (Figures 12 and 13) located in a corner of the building. In the console a r e located the following operating controls and indicators :

a. Control power key switch.

b. Two safety rod motor switches (spring loaded), "in" and "out" l ights , and position indicators .

c. Safety plug a i r cylinder operating buttons, "up" and "down" l ights , jack motor switch (spring loaded), position indicator, jack contact light.

d. C o n t r o l r o d m o t o r swi t ch ( s p r i n g loaded) , " in" and "out" l igh t , p o s i t i o n i n d i c a t o r .

e. S c r a m bu t ton .

f. Slow shu tdown bu t ton and l ight .

g. A n n u n c i a t o r pane l to i nd ica t e c a u s e of s c r a m , open h o l e s , and h igh r a d i a t i o n l e v e l . Inc ludes a l a r m h o r n and p r o ­v i s i o n for b y p a s s i n g i n t e r l o c k s on cool ing a i r and s o u r c e .

The r e a c t o r h a s a n u m b e r of s t a r t u p and s c r a m i n t e r l o c k s to a s s u r e p r o p e r o p e r a t i o n . An a n n u n c i a t o r l ight pane l i n d i c a t e s which i n t e r l o c k c a u s e s s c r a m . C o m b i n e d with the a n n u n c i a t o r pane l is an i n t e r l o c k b y p a s s and i n d i c a t o r l igh t s y s t e m for j u m p e r i n g out s o u r c e and coo l ing a i r i n t e r l o c k s by m e a n s of key a c t u a t e d s w i t c h e s m a r k e d " J " in the fol lowing t abu l a t i on . Both of t h e s e s y s t e m s a r e in full v iew of the o p e r a t o r . T h u s , it is p o s s i b l e to o p e r a t e the r e a c t o r wi th no cool ing a i r when t e m p e r a t u r e s t a b i l i t y i s d e s i r e d a t v e r y low p o w e r . C e r t a i n s t a t i s t i c a l e x p e r i m e n t s a t v e r y low p o w e r r e q u i r e o p e r a t i o n without the s o u r c e b e c a u s e of the p e r t u r b a t i o n it r e p r e s e n t s to the s m a l l n e u t r o n popula t ion . The s o u r c e m a y be r e m o v e d only a f t e r c r i t i c a l i t y is a t t a ined .

7. S c r a m I n t e r l o c k s

The fol lowing o c c u r r e n c e s c a u s e s c r a m :

a. High p o w e r l e v e l (two c i r c u i t s )

b . Shor t p e r i o d , i . e . l e s s than 15 s e c o n d s , (two c i r c u i t s )

(J) c. S o u r c e l e a v e s "in" p o s i t i o n

(J) d. R e a c t o r cool ing b l o w e r goes off

e. S c r a m a i r p r e s s u r e d r o p s be low 100 p s i in e i t h e r a c c u m u l a t o r

f. Safety p lug l e a v e s "up" pos i t i on or con tac t with j ack excep t on s low shutdown

g. F u e l t e m p e r a t u r e r e a c h e s 120°C

h. P o w e r f a i l u r e - c o n t r o l D.C. o r i n s t r u m e n t A .C .

i. F a i l u r e of c h a m b e r h igh vo l tage

8. Startup Interlocks

In o rde r to s t a r t up the reac tor the following conditions must be met:

a. Source in the reac tor

b . Reactor cooling blower and pit exhaust blower both on unless interlock is jumpered

c. Scram a i r p r e s s u r e above 100 psi

d. Safety plug jack in "out" position

e. Control rod in "out" position

f. Safety and period ci rcui ts r e se t

9. Startup Sequence

After the s tar tup inter locks a r e satisfied, the sequence r e ­quirements pe rmi t only the following order of events:

a. Inser t safety rods

b . Raise safety plug to "up" position

c. Inser t control r o d .

10. A la rm Interlock

Any of the following occur rences will sound an a l a r m and be indicated by the annunciator panel:

a. High radiation level in sub- reac to r pit

b . High radiation level in reac to r cooling exhaust filter

c. High stack activity

d. Opening pit manhole or any of the horizontal holes in the shield.

C. Reactor Instrumentat ion

The reac tor ins t rumentat ion (Figure 14 is a schematic) includes:

1. One pulse counter (BF3) channel with sca le r (additional channels will be used for initial loading).

2. One ion chamber and l inear amplifier channel with r e c o r d e r for operat ional control .

3 . Two ion c h a m b e r and l i n e a r a m p l i f i e r channe l s with power l e v e l t r i p and i n d i c a t i n g m e t e r s .

4 . Two ion c h a m b e r s and l o g a r i t h m i c a m p l i f i e r c h a n n e l s . T h e s e c h a n n e l s o p e r a t e the p e r i o d m e t e r , p e r i o d s c r a m s , and a dua l pen r e c o r d e r for log power and p e r i o d .

The r e a c t o r a l s o h a s the fol lowing t e m p e r a t u r e i n s t r u m e n t a t i o n :

5 . One fuel t e m p e r a t u r e t h e r m o c o u p l e with p y r o m e t e r t r i p c i r c u i t .

6. One t h e r m o c o u p l e s e l e c t o r swi t ch and ind ica t ing p y r o m e t e r for the fol lowing t e m p e r a t u r e s :

a . Inlet a i r

b . Out le t a i r

c . B lanke t - i n n e r edge

d. B lanke t - o u t e r edge

Al l of the a m p l i f i e r c h a s s i s , m e t e r s , i n d i c a t o r s , r e c o r d e r s , e t c . for the above i t e m s a r e l oca t ed in the c o n t r o l c o n s o l e .

Ion c h a m b e r s a r e two inch d i a m e t e r , B coa ted , p a r a l l e l p l a t e t y p e . They a r e l oca t ed in v e r t i c a l h o l e s , a s shown in F i g u r e 4, e i t h e r in the sh ie ld o r t h e r m a l c o l u m n . The BF3 pu l se coun te r i s l oca t ed in one of the v e r t i c a l h o l e s in the t h e r m a l c o l u m n .

D. R e a c t o r P h y s i c s

P h y s i c s c a l c u l a t i o n s a r e b a s e d on the e m p i r i c a l da t a ob ta ined in Topsy. ' ' •'One T o p s y con f igu ra t i on was a p s e u d o s p h e r e of v e r y n e a r l y the s a m e c o m p o s i t i o n a s the A r g o n n e F a s t S o u r c e R e a c t o r . E x t e n s i v e s u b s t i t u t i o n e x p e r i m e n t s w e r e p e r f o r m e d in th i s a s s e m b l y and i t i s f r o m t h e m tha t the w o r t h s of r o d s and h o l e s w e r e c a l c u l a t e d . The Topsy s p h e r i c a l d a t a a r e an e x c e l l e n t a p p r o x i m a t i o n for the w o r t h s a long the a x i s and a long a m i d p l a n e r a d i u s in a 1:1 c y l i n d e r . F o r o the r p o s i t i o n s a chopped (cos) we igh t ing was u s e d . S t r e a m i n g effects w e r e n e g l e c t e d .

A n o t h e r Topsy a s s e m b l y was a p s e u d o c y l i n d e r having the s a m e c o m p o s i t i o n a s the p s e u d o s p h e r e and v e r y n e a r l y the d e s i g n d i ­m e n s i o n s of the A r g o n n e F a s t S o u r c e R e a c t o r . The c r i t i c a l m a s s was 18 k i l o g r a m s , but t h e r e be ing no s u b s t i t u t i o n da t a a v a i l a b l e , it was n e c e s ­s a r y to c o r r e c t for vo ids wi th v a l u e s ob ta ined f r o m the Topsy s p h e r e a s d e s c r i b e d a b o v e . The e s t i m a t e d c r i t i c a l m a s s i s 20 k i l o g r a m s . The w o r t h s of the v a r i o u s r o d s and h o l e s a r e t a b u l a t e d in Tab le II .

Table II

REACTIVITY EFFECTS

Item

Control Rod

Safety (or shim) Rod

Minimum Fuel Increment before canning

Shim disc Gap Worth

Glory hole

Beam Hole

Grazing Hole

Cooling Annulus

Foil Recess

Effective Delayed Neutron Frac t ion

Descript ion

1" d iameter 6" effective length dk -T— at normal inser t ion ra te of 3" per minute dt ^ 2" d iameter 6" effective length dk -;— at no rmal inser t ion ra te of 4" per minute dt ^

4\" d iameter x .050" thick

4 i " d iameter x 0.100" thick .050" gap between safety plug and s tat ionary fuel dk / -r—when safety plug r i s e s normal ly 1/4" per minute dk •T— when safety plug r i s e s at 2" per minute dt dk — when safety plug r i s e s at 18" per minute 1/2" horizontal hole thru center of core and extending thru blanket (worth of hole - void v e r s u s U^'" in core U^" in blanket) 2^" horizontal hole in blanket extending toward core center and dead ending 1/2" from core edge (void ve r sus U" ' ) 1 Yi" horizontal tangential hole in blanket passing 1-^" from core edge (void ve r sus U^ *) 1/1 6" around core - 1/8" above and below core (void v e r s u s U^ ' ) 1^" d iameter x 5/32" deep on core axis and 1/2" below mid plane (void ve r sus U^^)

Worth Ak/k

0031

000026 s e c " '

0066 per rod

000075 s e c ' '

0.0041

0082 0044

00037 s e c " '

0029 s e c " '

027 s e c " '

0.0132

After initial evaluation, the potential react iv i ty effect of this hole will be reduced Ak

.0007 "jT" by means of the spacer assembly shown in Figure 16.

0030*

00068

0127

0030

0068

to

E. Reactor Building

The building to house the Argonne Fas t Source Reactor is located near the present ZPR building as shown in Figure 15. The AFSR building has its own heating plant and a i r compres so r . There is no water plumbed into the building.

F igure 16 shows the Argonne Fas t Source Reactor Building, a 32 foot by 32 foot by 20 foot high, prefabricated Butler- type building. The in ter ior of the building is insulated with 1 -1 /2 inches of fiber glass and will be lined with corrugated steel to a height of 10 feet. Two person­nel doors and a 12 foot by 13 foot overhead freight door make this building eas i ly access ib le for personnel and vehic les . A 480 volt, 3 phase, 60 cycle power supply of 100 ampere capacity is brought over from the main ZPR ci rcui t b reaker through a 100 amp b reake r . Five separate b r anchb reake r s will then control c i rcui ts for the building exhaust blower, reactor cooling blower, c rane , welding recep tac les , and lighting and instrument power and reac tor control power (AC).

Calculations indicate that as much as 42,500 Btu/hr of heat may be l iberated by ins t ruments , light, personnel , e tc . in this building. To maintain a comfortable summer a i r t empera tu re in the building this heat must be removed by ventilation and a complete change every two minutes will be requi red . The two gable mounted exhaust blowers , equipped with automatic louvres , have a combined capacity of 9500 cfm.

The a i r supply for controls comes from the compresso r in­stalled for that purpose . Air (125 psi minimum) from the compressor tank will be stored in two accumulator tanks of 2.5 ft. total capacity located in the reac tor pit. This will be adequate for scramming, even in the event that compres so r se rv ice is in terrupted.

F . Site

This facility is located in the same exclusion a rea as the Zero Power Reactor III and Exper imenta l Breeder Reactor I at the National Reactor Testing Station in Eas t e rn Idaho. Figure 17 is a site map showing the location in relat ion to other site ins ta l la t ions . The nea res t populated off-site a r e a s a r e Arco, (population: about 2000) about 18 miles west nor thwest and Atomic City, (population: about 200) about 12 mi les south­eas t . Except for EBR, BORAX and ZPR-III (extant Argonne facilities) the nea re s t populated location is Central Fac i l i t i es , three and one-half miles nor theas t . The nea re s t approach of U.S. Highway 20 is about 1-3/4 miles to the nor theas t .

The site is a dese r t plain of volcanic origin; i ts elevation averages about 5000 feet. The annual precipi tat ion averages about 1-l/Z inches of which a major portion falls as snow. The porous volcanic surfa absorbs water so readily that the re is negligible surface dra inage . The water absorbed sinks to the water table at a depth of about 600 feet where it is diluted by the waters of the Big Lost and Little Lost Rivers and Birch Creek which end their courses by sinking along the northwest edge of the site through the volcanic plain to an impervious s t r a tum.

Air m a s s e s reaching this a r ea must pass over mountain b a r ­r i e r s where a large share of their mois tu re is precipi ta ted . As a resul t , site relat ive hunnidity is normal ly very low, perhaps 20% on a summer afternoon. The low humidity together with the altitude pe rmi t s intense solar surface heating during the day and rapid radiat ion at night giving large diurnal t empera tu re var ia t ions , typically 30°F. The ext reme t empera tu re range for the si te is considered - 45° to 105°F.

F igure 18 is the wind r i s e at the 20 foot level at Central Faci l i t ies for November 1952 through December 1956. There is little difference in seasonal wind behavior . Typically the s t ronger southwest and west southwest winds occur at or after the hottest pa r t of the day while the nor theas t and north nor theas t winds tend to occur at night or very ear ly morning .

SECTION n

MANAGEMENT OF THE REACTOR

Optimum employment of the reac tor requ i res that it be readily available to staff m e m b e r s requir ing i ts flux in their work. The mode of operat ion descr ibed here is designed to meet the above cr i te r ion insofar as is compatible with safe operat ion.

A. Staff

1 . A Chief Physic is t designated by the Idaho Division Director will be responsible for the safe operat ion and proper use of the r eac to r . He and his a l te rna tes will be thoroughly familiar with the physics and functioning of the r e a c t o r .

2. Staff m e m b e r s who may need to use the reac tor will be d e s ­ignated qualified Supervisors by the Division Director when, in his judg­ment, they have had sufficient t ra ining to oversee operation.

3. The Division Director will designate a reasonable number of qualified technicians as opera to r s who will normal ly handle actual opera ­tion of r eac to r cont ro ls .

4. A minimum of two persons will be required to operate the r e a c t o r :

a. A staff member (Chief Physic is t , Alternate Chief Physic is t or Qualified Supervisor ).

b . A qualified technician operator .

B. Initial Startup

1 . The initial s tar tup will be made under the supervision of the Division Director or Chief Phys ic is t .

2. For initial s tar tup the two upper core pieces will be canned in final form, but the discs making up the lower core section will be left ba re so that they can be loaded incremental ly to obtain the cr i t ica l m a s s .

3. The pr incipal react iv i ty measu remen t s will then be made, including worths of all rods , worth of fuel, worth of gap, and the t emper ­ature coefficient of react iv i ty .

4. The beamhole l iner shown in Figure 19 will be fabricated with the length of the spacer section adjusted so that the react ivi ty change

c a u s e d by f i l l ing the b e a m hole wi th so l id b lanke t m a t e r i a l wi l l be l e s s Ak

than 0.0007 -—. k

5. The r e a c t o r wi l l be shut down and the fuel d i s c s n e c e s s a r y to f o r m a c r i t i c a l m a s s wi l l be r e m o v e d and canned a s one uni t .

C. O p e r a t i o n

1. The Chief P h y s i c i s t and Div i s ion D i r e c t o r wi l l e ach have c u s ­tody of a se t of a l l r e a c t o r k e y s , inc luding t hose to r e a c t o r c o n t r o l power swi tch , the g l o r y ho le , the s h i m r o d a d j u s t m e n t , the two j u m p e r a b l e i n t e r ­l o c k s , and the p r e s s u r e r e g u l a t o r con t ro l l i ng the speed of the a i r cy l i nde r

2. N o r m a l l y the s h i m r o d s wi l l be ad jus ted so tha t p e r i o d with the c o n t r o l r o d fully i n s e r t e d wi l l not be s h o r t e r t han 3 0 s e c o n d s .

3 . F o r a r o u t i n e e x p e r i m e n t , a qual i f ied s u p e r v i s o r m a y ob ta in the a p p r o v a l of the Chief P h y s i c i s t , be i s s u e d the c o n t r o l power key , and p r o c e e d wi th h i s w o r k wi th the a id of one o p e r a t o r .

4 . F o r a n o n - r o u t i n e e x p e r i m e n t r e q u i r i n g :

a. Use of g l o r y hole b . A d j u s t m e n t of s h i m r o d s c . I n s e r t i o n or r e m o v a l of s h i m d i s c d. P o w e r l e v e l ove r 50 w a t t s e . P e r i o d s h o r t e r than 30 s e c o n d s

the i n t e r e s t e d s u p e r v i s o r wi l l d e s c r i b e the e x p e r i m e n t in w r i t i n g with cop ies to D iv i s ion D i r e c t o r and S e c r e t a r y of Idaho Div i s ion C o m m i t t e e on R e a c t o r Safety and ob ta in the w r i t t e n a p p r o v a l of the Chief P h y s i c i s t t o g e t h e r wi th the a p p r o p r i a t e k e y s .

5. W h e r e he j udges it d e s i r a b l e , the Chief P h y s i c i s t wi l l p e r s o n a l l y s u p e r v i s e the e x p e r i m e n t .

6. Al though the r e a c t o r h a s b e e n d e s i g n e d for o p e r a t i o n at a n o m i n a l m a x i m u m power of 1000 w a t t s , it i s e a s i l y p o s s i b l e t ha t t h e r e h a s b e e n o v e r d e s i g n in coo l ing and sh i e ld ing . The a c t u a l m a x i m u m power l e v e l s e t for the r e a c t o r wi l l be tha t power at wh ich the sh ie ld ing is adequa t e to k e e p the o p e r a t i n g a r e a be low t o l e r a n c e r a d i a t i o n l e v e l and a l s o at which the cool ing s y s t e m is adequa te to k e e p the m a x i m u m fuel t e m p e r a t u r e be low 120°C.

SECTION m

HAZARDS

A. General

Both reac tor design and use mil i ta te for safety. The cr i t ica l load­ing must be es tabl ished in the usual stepwise fashion, but once the cr i t ica l loading is found and shim rods adjusted, there is little need for varying the react iv i ty beyond the range available in the control rod. The t e m p e r a ­ture l imitat ion of 120°C means very l i t t le excess react ivi ty is required to over r ide the the rma l effect on react iv i ty . The nominal power will permi t an a lmost l imi t less operating life without significant effect on react ivi ty. In the event that the shim rods must be moved to adjust react ivi ty for a specific exper iment , their adjustment is subject to checking by at least the Supervisor and Chief Physic is t .

The design and density of the core and blanket a re such that a lmost any credible deformation or heating of the reac tor reduces react iv i ty .

The extensive m e a s u r e m e n t s done on Topsy (LA-1708) form a sound bas i s for es t imates of c r i t i ca l m a s s and react ivi ty effects. S4 calculations for a spher ica l idealization of the actual reac tor give a t he rma l coefficient of react iv i ty of -9-4 x 10" /°C Ak/k for adiabatic heating of the core ; i .e . , when heating takes place so quickly that the core expands outward in the cooling annulus without any corresponding heating and expansion of the blanket. For more gradual heating, the expansion of the blanket inc reases the effect.

It was not ce r ta in that the S4 calculations gave good resu l t s for a core expanding into an annular void, and further runs were made on a core-blanket sys tem with no annulus. The tempera ture coefficient for a reac to r having an annular void was found to be one-third that of s imilar sys tem without the void. A rough mock-up of the sys tem was assembled in ZPR-III and react ivi ty measu remen t s were made on the cr i t ica l con­figuration. F i r s t , the core was expanded in one dimension into a void and the react ivi ty change measu re d . Then, a react ivi ty measurement was made in a situation in which (there being no void) the core and blanket were moved together in a simulated expansion. Both cases exhibited a negative react ivi ty effect with the "void" case having about one-third the effect of the "no-void" case . Since this was one-dimensional experiment on a crude mock-up, it can only be considered qualitative confirmation of the S4 calculat ions.

In view of the recent work by Kato and Butler,'^^ the Doppler effect on react ivi ty is considered negligible.

Although the c r i t i ca l m a s s is es t imated as 20 k i lograms , 25 ki lo­g rams of fuel will be fabricated. Except for one shim disc of 480 g r a m s , all excess fuel will be re tu rned after the cr i t ica l m a s s is determined and lower core section canned.

Installation of fuel pieces is free of nuclear hazard under any imaginable conditions. Each of the two canned sections compris ing the s ta t ionary upper portion of the core weigh on the order of 7 k i log rams ; ei ther separa te ly or together , they a re comfortably below the minimum cr i t ica l m a s s for dense metal l ic uranium-235 (about 17 k i lograms in an infinite blanket of maximum density natura l uranium and somewhat more in a hydrogenous b lanket ) .^^ Once the stat ionary par t of the core has been instal led, the remaining 11 k i lograms a re likewise safe to handle outside the r eac to r . Initial loading steps can be as low as 240 gms or a Ak of 0.0041.

B. Method of Calculation

A number of excurs ions ( summarized in Table III) have been ca l ­culated and a re d iscussed in the var ious appendices.

Table III

SUMMARY OF EXCURSIONS STUDIED

Appendix

n n

Gra

Fig Fig Fig Fig Fig

ph

18 19 20 21 22

Ak/k

010 029 009 027 089

0023 0043

dk/kdt (sec-')

0004 0004 003 003 03

000026 ( 0043 step)

Time Between Delayed Critical and Prompt

Critical (sec) Failures*

17 ABCD 17 ABCD 2 3 ABCE 2 3 ABCE 0 23 ACF

ABCD ABCD

The scram interlock or control failures which must occur to allow the excursion m question to lead to a serious incident are listed below together with the identifying letter for use m the Table

A Both period meters fail to scram on short period B Operator fails to act on short period, high power, or high temperature

indications or the instruments fail to indicate the condition of the reactor

C Both power level safety circuits fail to scram on the high power level D The temperature circuit fails to scram on high temperature E Jack failure permits assembly at intermediate speed of two inches

per minute F Jack runout feature fails and interlock fails on jack down requirement

for startup

The basic excursion problems were worked on Argonne's IBM 650 Computer using Code RE29.^^' Code RE29 yields the space independent behavior of a sys tem in which

dk , - = A + Bn

where A is a constant represen t ing the slope of a react ivi ty input r amp and B is the coefficient relat ing power (proportional to neutron population) to t ime ra te of change of react ivi ty . B can be obtained as follows:

We approximate the fission ra t e (f ission/sec/cm^) as —7 where vi

n is the population of neu t rons / cm V is neut rons / f i ss ion (2.5) i is prompt neutron lifetime ( 2 x 1 0 " sec)

dE , n .24 — cm = -^ — - ^ = n X 1 .55 X 10 ' c a l o r i e s / c m

de dE ..3 1 cm X-dt dt specific heat x density

n X 1.55 X 10"* .035 X 19

= n X 2.3 X 10" degree C/sec

Bn = - ^ = ^ x ^ = n x 2 . 3 x l O " * (-9.4 x l O ' ^ ) dt dt d0

B = -2 X 10"^

These r e su l t s were then extrapolated to a spher ical idealization of the actual r eac to r by means of the power distr ibution obtained in the p r e ­viously mentioned S4 calculation. F igures 20 through 24 represen t the predic ted behavior of this spher ica l ideal :

Core radius 6.13 cm Cri t ica l m a s s 18.1 kg Annular void 0.2 cm Effectively infinite blanket

The solid t empera tu re curves r ep re sen t the limiting values which per ta in to the case of no heat conduction. However, depending on the t ime scale of the excursion, conduction may substantially ameliorate the indicated t empera tu r e . In any event, as the outer portion of the core me l t s , the fuel m a s s col lapses into contact with the blanket; the core

boundary is then held at or below the melt ing point of uranium because of the heat sink represen ted by the heat of fusion in the mass ive uranium blanket ma te r i a l .

C. Types of Incidents Considered

1. Appendix I covers five excurs ions which might a r i s e from e r r o r s in loading, coupled with operator e r r o r and/or failures of inter locks or s c r a m c i r cu i t s .

(a) The reac to r having been overloaded by about 1/2 k i logram goes c r i t i ca l when the safety plug is 0.1 inches from the fully assembled position and moving at the slow assembly speed of 1/4 inch per minute . If multiple personnel and circui t fa i lures occur , an excursion such as is plotted in Figure 20 may be observed. The excurs ion re su l t s in some melting of the core and contamination of the r e ­actor pit. The reac tor cooling sys tem and pit ventilation will probably prevent contamination from reaching the floor level of the building. The maximum personnel exposure will be about 10 m r .

(b) The reac to r having been overloaded by about 1 j k i lograms goes c r i t i ca l when the safety plug is about 0.3 inches from the fully assembled position. The conditions a re o ther ­wise the same as in the foregoing case . The re su l t s a re plotted in Figure 21 . There is severe melt ing of the core but probably no vaporizat ion or disruption of the blanket. Maximum exposure of operating personnel is about 21 m r .

(c) Figure 22 is a plot of the core in which the reac tor b e ­comes c r i t i ca l at 0.1 inches (about 1/2 k i logram over ­load) and the safety plug is t ravel ing at the in termedia te speed of 2 inches per minute. The integrated excursion is of the same size as the one descr ibed in (a) above.

(d) Figure 23 is a plot of the predicted excursion in which the reac tor becomes c r i t i ca l at a separat ion of about 0.3 inches while the safety plug is t ravel ing at 2 inches per minute . The re su l t s a re essent ia l ly those for the same overload and slow speed assembly in (b) above. The shortened t ime scale does dec rease the effect of conduction and there will probably be some vaporizat ion of fuel.

(e) Figure 24 r ep re sen t s the predicted behavior in the severe case in which the reac to r , overloaded by about 5 ki lograms goes c r i t i ca l when the safety plug is one inch from the fully assembled position and traveling upward at the air cylinder speed of 18 inches per minute. This resu l t s in a violent excurs ion which is te rminated by blowing the safety plug downward. The molten core ejected into the pit burns with the l iberat ion of a great amount of chemi­cal energy. The reac tor is destroyed and the pit and tunnel a re heavily contaminated. Radioactive ma te r i a l will be blown out into the reac tor building through the reac to r por t s and par t icu lar ly the manhole. Some con­tamination will probably reach the outside through the pit ventilation ducts .

Although it is reasonable to expect that fission products will be la rgely contained in the pit and building. Appendix I es t imates that the hazard to other personnel is not severe even in the ca se of g ross re lease of a radioactive cloud.

Appendix 11 is concerned with excursions which might a r i s e from human failure in reac tor operations combined with failure of var ious s c r a m c i rcu i t s .

(a) In the f i rs t case the proper ly loaded and functioning (except for power level and tempera ture t r ips) reac tor rxins out of control due to an inattentive or suddenly disabled opera to r . This excursion is l imited to about 3600 watts power level by the negative t empera tu re co­efficient even if the power level t r ips fail to s c r a m . The core average t empera tu re reaches about 265°C. No damage is anticipated and the shielding is adequate to guarantee that personnel exposure will not exceed 30 mr per hour until the reac tor is shut down.

(b) The second case is one in which poor teamwork between an exper imenter and the operator resul t in the sudden addition of 2.0 x lO"'^ Ak/k while the reac tor is on a minimum allowable period of 1 5 seconds. If both period t r i p s , both power level t r i p s , and the core t empera tu re t r ip fail, the power is l imited by the negative t empera ture coefficient to about 7000 watts and an average core t em­pera tu re of 480°C. No damage to the reac tor is ant ic i ­pated and maximum personnel exposure is at the ra te of about 50 m r per hour until the reac tor is shut down.

D. Hazard in Retrieving Foils

The pr incipal hazard in normal operat ion appears to be the r a d i a ­tion received when re t r iev ing foils from the lower core section after a run at sustained power. A calculation was made of the radiat ion levels to be expected after a one hour run at one kilowatt power. The radiation level 100 seconds after te rminat ion of the rxin at a point 2 cen t imete rs above the lower core section (approximate position of hand in removing foils without tools) is of the order of 5 x 1 O* roentgens per hour. At 1000 seconds after the end of the i r rad ia t ion , the level is about 1.5 x 1 C* roentgens per hour.

The lead ring and blanket section of the plug constitute a fairly good, although open-topped, gamma shield. The radiation level at a horizontal distance of one me te r frora the shield (within reasonable operating distance with tongs) is about 0.8 roentgens per hour 100 seconds after radiat ion. Thus, foils can be re t r i eved without excess ive exposure provided caution is exerc i sed to avoid the di rect beam from the top of the core section. In doubtful cases involving intensive i r rad ia t ion , smal le r foils can be exposed in the glory hole, from which they can be re t r i eved with vir tual ly no personnel exposure .

E. Miscellaneous Hazards

1. Since both core and reflector a re at maximum density, it is ex t remely unlikely that an ear thquake, no mat te r how severe , could in itself inc rease react ivi ty by some displacement of reac to r components . However, there is the possibil i ty that an earthquake might in some way freeze the controls when the reac tor is on a 30 second period; the negative t empera tu re coefficient will compensate the 60 inhours excess react ivi ty when the t empera tu re has r i sen about l60°C. This c o r r e ­sponds to an equil ibrium power of 3000 watts if the air flow is maintained and something much less if the cooling air s tops.

2. Flooding is not credible in view of the NRTS meteorology ajid the siting of the r eac to r . The cooling air intake is about 3 feet above the floor so that local water from freakishly melting snow cannot be drawn into the r eac to r , even in the remote event that it might rxin onto the reac tor building floor. The filter on the cooling air intake prevents any solid ma te r i a l from being drawn into the reac tor by the air s t r e a m .

3. The react ivi ty of the cooling air is negligible. At nominal power of 1000 watts , carbon-14 (half-life 5600 years ) will be produced at the ra te of 10"^"* cur ies per second by the react ion N '*(n, p) C '*. Nitrogen 16 (half-life 7.4 seconds) will be p r o ­duced byO^^(n, p)N^^ at the ra te of about 5 x 10"^ cur ies second.

CONCLUSIONS

The following points can be made concerning the safety of the Argonne Fast Source Reactor :

1 . The t empera tu re coefficient is negative, -9.4 x 10" Ak/k per °C.

2. The policy of operating with a fixed loading of l imited excess react iv i ty leaves li t t le opportunity for dangerous personnel e r r o r . Significant changes in react ivi ty a re r igorously con­t rol led by locking the glory hole and shim rods .

3. The inter lock sys tem and s c r a m instrumentat ion are such that a very improbable number of simultaneous failures must occur if a personnel e r r o r is to resu l t in a significant excursion.

4. Both core and blanket a r e of maximum density nnetal; any credible dis tort ion reduces react ivi ty.

5. In the event of a severe excursion the isolation of the s i te , the prevail ing winds, and the low inventory of fission product all tend to reduce the number of persons exposed and the sever i ty of exposure .

REFERENCES

1. LA-1708 "Mater ia l Replacement in Topsy and Godiva Assembl ies "

2. De M a r r a i s , G. A. "The Cl imatory of the National Reactor Testing Station" IDO-12003

3. Kato, W. Y. and Butler , D. K. "Measurement of the Doppler Tempera tu re Effect in an EBR-I Type Assembly" ANL-5809

4. Paxton, H. C. "Cri t ical Masses of Fiss ionable Metals as Basic Nuclear Safety Data" LA-1958

5. Bri t tan, R. O.

"Some Prob lems in the Safety of Fast R e a c t o r s " ANL-55 77

6. AECU 3066 "Meteorology and Atomic Energy"

7. Orndoff, J . D., Nuclear Science & Engr. 2,450 (l957)

APPENDIX I

LOADING ERROR WITH MACHINE FAILURE

1. The leas t improbable case is that in which the reac to r with controls operating normal ly , goes cr i t ica l while the plug is moving up­ward at the slow final assembly speed of l / 4 inch per minute. This cor ­responds to a react ivi ty addition ra te of .0004 Ak/k per second, giving 17 seconds from delayed to prompt c r i t i ca l . For this situation to lead to an accident, the following fai lures mus t occur.

a. Both per iod m e t e r s fail to s c r a m on the excessively short per iod.

b . Operator fails (17 seconds between delayed and prompt cr i t ica l ) to act on short period, high power, and high t em­pe ra tu re indicat ions, or the ins t ruments fail to indicate the condition of the r eac to r .

c. Both power level safety circui ts fail to s c r am on the ex­cess ive power level .

d. The tenaperature safety circui t fails to s c r am on the high t e m p e r a t u r e .

The behavior of the r eac to r going cr i t ica l when the safety plug is st i l l 0.1 inches from the fully assembled position under the above a s ­sumptions is plotted in Figure 20. This corresponds to an overload of about one-half k i logram.

At 30 seconds the reac to r power is about 4200 ca lo r ies / second (17.5 kilowatts) and slowly decreas ing . The total integrated power is 1.1 X lO^calories (4.6 x 10^ wat t -seconds or 1.4 x 10^^ fissions) and the de­c reased power level is adding to the integrated power very slowly. The reac to r eventually beconnes subcr i t ica l through any, or a combination, of the following:

a. Loss of core m a t e r i a l by molten flow through the lower a i r hole or glory hole.

b . Loss of core m a t e r i a l through oxidation.

c. Loss of core enrichment by admixture of uranium-238 mel ted from the blanket.

The reac to r shield is designed to give l ess than 7.5 m r per hour at nominal power (1000 watts) at any point against the outside of the shield. This cor responds to a total integrated power of 3.6x 10 watt-seconds per hour; so the maximum personnel exposure from this excursion would

be about 10 m r , excluding in terna l hazard from fission products that might be sca t te red about. Most fission products formed should be contained by the reac to r a i r cooling sys tem filter and pit ventilation sys tem filter if the fans continue operat ion. In any event the fission product r e lease is small since the core does not vapor ize and the blanket and shield a r e not disrupted.

The foregoing mus t be qualified by the uncertainty as to the behavior of the uranium pieces in int imate contact with the nickel cans. The U-Ni eutectic has a mel t ing point (738° C) much lower than that of pure uran ium. As a resu l t , it is possible that localized mel t ing may take place on the uranium surfaces in contact with the can sooner than predicted by the graph. The overal l effect of eutectic formation should be smal l since the amount of nickel is snaall and it is not intimately mixed with the u r a ­nium. No ser ious inc rease in react ivi ty can occur by ear ly collapse of m a t e r i a l into the glory hole because the glory hole l iner is separa ted from the fuel by 10 mi l s of z i rconium.

2. F igure 21 is a s imi la r plot of the case in which the reac tor at the same slow speed goes c r i t i ca l approximately 0.3 inches from the fully assembled posit ion. This occur rence depends on the same ins t rumenta l and operator fai lures as were enumerated in the preceding case . This amount of excess react ivi ty cor responds to an overload of about one and one-half k i lograms of fuel. Again the solid t empera tu re l ines r ep resen t the limiting adiabatic ca se . The dotted line is the actual behavior of the core surface t e m p e r a t u r e . In all probability the t ime scale is long enough that conduction substantial ly reduces the t empera ture from the simple p r e ­diction plotted and probably no vaporizat ion occurs . .

The total in tegrated power in this excurs ion is about 2 .5x 10 ca l ­or ies (1.0 X 10^ wat t -seconds or 3.1 x 10^^ fissions). The maximum external (gamma and neutron) radiat ion exposure of operat ing personnel is about 21 m r

3. F igure 22 is plotted for the case of l / 2 ki logram overload in which the speed change fails and the jack r e t r a c t s at i ts high speed of two inches per minute .

The jack is designed to make the speed change mechanical ly cer ta in; however, improper assembly and incomplete test ing of the jack might permi t incor rec t location of the speed changeover point. Should this pe rmi t assembly at the higher jack speed, the r eac to r would go c r i t i ca l 0.1 inch from the fully a s sembled position at the ra te of 0.003 Ak/k per s e c ­ond. (2.3 seconds between delayed and prompt cr i t ica l ) . The same ins t ru ­menta l and operat ional fai lures apply as in the preceding cases except that the thermocouple may be too slow to act . It is seen that the net resu l t in t e r m s of total integrated power is vir tual ly the same as in Figure 20.

4. F igure 23 shows the case in which the reac tor goes cr i t ica l 0.3 inches from the fully assembled position ( ly ki logram overload) at the same assembly ra te of two inches per minute. Otherwise, the situation is the same as in the preceding case . The integrated total power of the ex­cursion is the same as in F igure 21 , in which the same amount of reactivity was added at the slow ra te of a s sembly . However, the faster t ime scale reduces the effect of conduction at the peak of the excursion and some va­porizat ion may occur .

In al l of the foregoing cases the t empera tu re r i se is on the t ime scale of severa l seconds so that it is unlikely that any shock-like thermal expansion will affect the react ivi ty.

5. F igure 24 is a plot of expected behavior when, in addition to the other fai lures mentioned in (1) above, the jack automatic runout provision and assoc ia ted inter locks fail. In this case , the r eac to r is assumed to go cr i t ica l one inch from the fully a s sembled position corresponding to about 5 k i lograms overload (extra fuel discs will no longer be available after the c r i t i ca l loading has been determined) at the speed of the a i r cylinder (18 inches /minute) . This adds react iv i ty at the ra te of 0.03 Ak/k per second. Peak power is of the o rde r of 2.3 x 10 calor ies per second. If all the heat goes to vaporize fuel, it will vaporize 5.7 x 10 g rams per second which cor responds to 550 l i t e r s (STP) or about 8000 l i t e r s per second at the ex­isting t empera tu r e .

The safety plug unit, including piston and piston rod, weighs about 150 pounds. Since it is moving upward at a constant ra te of 1 8 inches per minute, all forces a r e in equil ibrium and a downward force will tend to r e v e r s e its motion. The above figures indicate that at 1.50 seconds after achieving cr i t ical i ty there is adequate vapor production to expel the safety plug downward.

The segmented ring of the blanket surrounding the core may also be pushed outward by the explosive evolution of gas . However, the sudden expansion of these ring segments is opposed by an iner t ia l loading of about 15 pounds per square inch, the friction with adjacent r ings , and the shear s t rength of one l / 2 inch s teel tie bolt or dowel. By contrast the expulsion of the safety plug is opposed, for that short t ravel which is s ig­nificant to react ivi ty, only by an iner t i a l loading of about 9 pounds per square inch.

It was hypothesized that the reac tor became cr i t ica l at a safety plug separat ion of one inch. At 1.50 seconds the plug is sti l l l ess than half an inch beyond the point of cr i t ical i ty; thus less than half an inch of down­ward motion will reduce the reac tor below cr i t i ca l . However, the violent downward thrus t will c a r r y the plug below the blanket so that the molten

uranium is sca t te red . The loss of m a t e r i a l prevents a repet i t ive cri t ical i ty even though the safety plug does bounce upward again on the cushion of a i r in the cylinder.

This sequence resu l t s in power and integrated power curves as shown in Figure 24. The total nuclear energy re lease is about 2 .8x10 ca l ­or ies or 3.6 X 10 f iss ions . Since it r equ i res 5.5 x 10 ca lor ies to vaporize a ki logram of uranium from room t empera tu re , substantially l ess t hanSk i l -ograms will be vaporized. A par t of the heat goes to melt ing the remainder of the core .

However, the molten uraniunn thrown into the pit may burn, add­ing a significant amount of chemical energy to the excursion. The a i r con­tained in the pit and tunnel amounts to some 500 cubic feet containing about 110 g ram molecular weights of oxygen. This is sufficient to burn 82 gram atomic weights (about 20 k i lograms) of uranium in U3O8, with the r e l ea se of approximately 2.3 x 10 ca lor ies (burning uranium r e l ea se s about 2.8 X 10 c a l o r i e s / g r a m - a t o r a ) .

Thus, the excursion will resul t in the r e l ease of not m o r e than about 2.5 X 10^ ca lor ies of which 90 percent is chemical energy. The 500 cu­bic feet of a i r in the pit and tunnel weigh about 1.5 x 10 g r a m s . The energy of the excursion is sufficient (taking the specific heat of a i r at constant vol­ume as 0.18 ca lo r i e s / g r am-°C) to r a i s e the t empera tu re of a i r in the pit to 1230°K. If this happens near ly instantaneously, the corresponding p r e s ­sure is about 37 psig. This could conceivably impa r t a velocity as high as 50 fee t /second to the manhole cover . Such a velocity would perhaps be suf­ficient to r each and rupture the roof. However, this is the upper l imit on the violence that might be expected. Some leakage will occur around the r eac to r plugs, but the comparat ively high m a s s loading relat ive to the s u r ­face exposed to the in ternal p r e s s u r e makes it unlikely that any significant motion will occur .

More rea l i s t ica l ly , the burning of the uranium will requi re a varying t ime depending on the exposed surface of the molten blobs ejected into the reac to r pit and the p rogress ive depletion of oxygen. Since the pit is vented through two 8 inch pipes (intake and exhaust of the pit ventilation sys tem), a high leakage ra te combined with a finite ra te of heat generation will great ly reduce the o v e r p r e s s u r e from the maximum es t imated above. It appears probable that the building will not rupture , and that a la rge amount of radioactive m a t e r i a l will be ejected into the building through the manhole with a l e s s e r amount conducted to the outside through the vent i la t ­ing sys tem exhaust (the intake is inside the building).

In summary , the foregoing analysis leads to the conclusion that the excursion hypothesized resu l t s in destruct ion of the reac to r , but ruptures

nei ther the shield nor the r eac to r building. There is intense contamination of the pit, tunnel, and reac to r building with some m a t e r i a l conducted to the outside.

However, to set an upper l imit to the hazard to other personnel which might ensue, two ex t reme cases of radioactive cloud emission have been considered. In the f i rs t case , it is postulated that a cloud containing one-half of all fission products escapes from the building at ground level. In the second case , the same cloud is a s sumed to reach the a i r through the top of the r eac to r building at a nominal height of 10 m e t e r s .

Table IV sumnnarizes the maximum doses which might be ex­pected should the clouds postulated pass directly over the receptor . The distances of 50 and 100 m e t e r s were used as being the round number d i s ­tances to ZPR-III and EBR-I respect ively . Holland's nomograph(D) was used to obtain the gamma doses and the beta doses were calculated from the following equation from the same re fe rence .

TID(Rep) = 4 . 8 . 1 0 " ^ ^ x ( 0 . 6 4 ) E , - u « ' . . p ( ^ : _ „ )

X [ ( 6 . 8 x 10'°Mev/riyr,)x7rC^d(^-"+'-^'^]"'

where

E = Excurs ion energy re lease (Mw-sec)

d = Downwind distance (meters) h = Cloud height, i .e . equivalent point source height from nomogran

(meters) u = Wind velocity (mete rs / second) n = Sutton stabili ty pa r ame te r C - general ized diffusion coefficient

The following values of the a tmospher ic p a r a m e t e r s were chosen as reasonably typical of the a r ea and were used in obtaining both gamma and beta doses .

n = 0.25 C= 0.20

Since the reac tor is to be operated only at low power, all fission products a r e a s sumed to originate in the excursion itself.

The following factors amel io ra te the above es t imates :

1. Except for an occasional guard on pat rol and pa r t - t ime lawn labor, a l l personnel within 3-| mi l e s (the distance to Centra l Fac i l i t i es ) a r e ei ther working in the EBR, ZPR, or anci l la ry buildings, or a r e t rans ient on the highway I f -mi les away. This protect ion would virtually eliminate any beta dose and considerably reduce the effect of gamma radiat ion.

2. The wind pat tern (see F igure 18) would c a r r y a radiat ion cloud toward EBR and ZPR less than 10 percent of the t ime .

Table IV

PROBABLE MAXIMUM DOSES FROM RADIATION CLOUD

Ground Level Cloud

Wind ( M / S )

Gamma Beta

Ganama Beta

50 Meters Downwind

15 r 180 Rep^

12 r 240 Rep^

100 Meters Downwind

3 r 23 Rep^

3 r 31 Rep^

Cloud Height 10 Meters

Gamma 5-j r 2^ r Beta 42 Rep^ 19 Rep^

Gamnria 4-j r 2-2-r Beta 56 Rep^ 2 5 Rep^

These a r e the bar skin beta doses . When the protect ion of ordinary clothing is considered, they may be too large by as much as an o rde r of magnitude.

APPENDIX II

ERROR OR MISHAP IN OPERATION

A dis t ract ion or sudden disabili ty of the operator while running in the control rod might lead to the control rod ' s being fully inser ted . Assume that the maximum react ivi ty the reac tor might ever requi re could be just that n e c e s s a r y to furnish a reasonable period at the top of the p e r ­miss ib le t empera tu re range; this would amount to roughly .0014 Ak/k to furnish the period and maximum of .0009 Ak/k to overr ide the t empera ture coefficient, or a total of about 100 inhours (2.3 x 10 Ak/k) above room tempera tu re delayed cr i t i ca l . This cor responds to an initial period of 15 seconds.

In the wors t case of the above type, the r eac to r would go up on a period of 1 5 seconds provided that the period me te r t r ip settings permit ted such a shor t period or that both period m e t e r s malfunctioned. If there is joint failure of t empera tu re and both power level t r ip s , the reac tor would increase in power until heating of the r eac to r reduced the reactivity below unity after which it would stabil ize at an average core t empera ture of

2 3 x 10"^ about 20 +-5-7 rrr(> ~ 265°C and a power level just equal to the equilibrium

heat loss for the above t e m p e r a t u r e . This t empera ture corresponds to a power level of about 3600 watts based on the fact that in the iron mockup the core , 1000 watts gave a r i s e of 67° C average core tempera ture over ambient. Maximum dose ra te to operat ing personnel is 27 m r per hour and no damage is done in the r eac to r .

Poor Coordination Between Exper imenter and Operator

Assume that the Chief Phys ic is t has approved an experiment in­volving i r rad ia t ion of foils in the glory hole and that the exper imenter is positioning the foils by means of a wooden rod which just fits the hole. If, while the r eac to r is coming up on a period, the rod is inadvertently in­se r ted so as to completely fill the section of the glory hole lying in the core an incident might occur because of the react ivi ty effect of the hydrogenous m a t e r i a l . If the wood is a s sumed to have a density of 0.65 and an approxi ­mate chemical formula of CH2O, the react ivi ty effect of the rod is 2.0 X 10"^ Ak/k based on substitution data in Topsy.

If the original period were 15 seconds corresponding to a reactivity of 2.3 X 10"^ Ak/k, the total react ivi ty would then be 4.3 x 10"^ Ak/k. This gives an initial per iod of about ZY seconds which becomes longer as the r eac to r heats up. Provided both per iod m e t e r s c r a m s , both power level s c r a m s , and the high t empera tu re s c r a m all fail, the tempera ture r i ses

until k is reduced to unity. This would be at a t empera tu re of about 4.3 X 10"^

20 -F ' rFr-(> ~ 480°C. The equil ibrium power level corresponding to

this t empera tu re is about 7000 watts , if the a i r c irculat ion is maintained. If not, then the ul t imate power level is something much l e s s . No ser ious damage to the r eac to r is anticipated and maximum radiation exposure to personnel is about 53 m r per hour.

eXHAUSr DUCT-f5.S.)

UPPO? CAN ASSeMBLY-

eN/?/CHeD U/?AWaM-

ro/L ^ecs^s

SHIM mJO HOL£ l/NER(S3.)

A//C/CSL CAN-

LOWeP CAN ASSSMBtr-(W/0/3KS)

A/P Wt£T DUCr-(S.3)

BIAN/C£T /?/m l/A/fP-

dLANA'£T feoi'a)

THPP'MOCOUPLE HOLE

TOP P16/(F ^SSSUJSL y

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M/OOLE CAM ASS£MSly

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LOW£P COP£ /?£7i4/A//A/G CAGE (S.S)

BOTTOM PLOG ASSEMBL K

DEPLETED UPAMl/M

I I I I I SCALE IN IMCHES

AFSR CORE ASSEMBLY FIG. 1

3^Ar//^ NC^£ —

SCALE IN INCHES

5H0lf^m ENmE BLANKET

—Gt£)ifr »oCE

—jue /MLsr oucT

AFSR BLANKET a CORE ASSEMBLIES

SHOWim 0«ne£ ULANKET

FIG. 2

GRAPHITE THERMAL COLUMN

VERTICAL INSTRUMENT HOLES

SHIELD-HIGH DENSITY CONCRETE

WIRING DUCT

GRAZING HOLE

BEAM HOLE

CONTROL ROD DRIVE

SOURCE DRIVE

JACK DRIVE

SAFETY ROD DRIVE

RELOADING COFFIN

AIR ACCUMULATOR TANKS

ARGONNE FAST SOURCE REACTOR

FIG. 3

REMOVABLE GRAPHITE STRINGERS

BLANKET-DEPLETED URANIUM

HORIZONTAL INSTRUMENT HOLES

CORE-ENRICHED URANIUM

PIT VENTILATION DUCT

ACCESS TUNNEL

SAFETY PLUG AIR CYLINDER

Thei^rnt^/ Co/i^mn

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SECTION A-A

REACTOR a THERMAL COLUMN

F I G . 4

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AFSR SAFETY ROD DRIVE ASSEMBLY

FIG.6

- 6

- 5

- 4 en iij X

o

_J UJ > <

- 3

- i CLUTCH F

/TIME

\ 'V

RELEASE/

(

/o

v j

r>./

/

) /

/

r\ \J

20 40 60 80

TIME MILLISECONDS

100

AFSR SAFETY ROD PERFORMANCE CURVE SCRAM PRESSURE= 130 psig SCRAM SIGNAL=0 Time

F I G . 7

125 PS I FROM COMPRESSOR

SAFETY

PLUG

AIR

CYLINDER

CLUTCH 1 RELEASE)

SAFETY ROD

NEEDLE

VALVE X

M' DE-ENERGIZED

3-WAY SOLENOID

VALVE

SCRAM

PRESSURE SWITCH

ACCUMULATOR

( 2 l/g CU FT ) 3/4

„ CHECK

VALVE

3-WAY SOLENOID

VALVE

RELIEF PRESSURE VALVES GAUGE

V

NEEDLE

25PSI 25PSI

PRESSURE GAUGE

PRESSURE REGULATOR

TUBING

20PSI

PILOT VALVE AIR SUPPLY

PRESSURE REGULATOR

40 PSI

VALVE

PRESSURE RELIEF GAUGE VALVE i

SCRAM A

CLUTCH 1 RELEASE

SAFETY ROD

25 PSI PRESSURE REGULATOR

1/4

15 PSI

n PRESSURE SWITCH

ACCUMULATOR

{I/4CU FT)

CHECK

VALVE

AFSR PNEUMATIC SYSTEM FIG. 8

SOLENC 1 )ID VAL\ •IMEy

/

'E

/

/

!

/

/

/

/ / /

/ /

/ \ '

20 4 0 6 0 80

TIME MILLISECONDS

100

AFSR SAFETY PLUG PERFORMANCE CURVE SCRAM PRESSURE = I25 psig SCRAM SIGNAL = 0 Time

120

FIG. 8a

S/fding Gtnftgcf for__ /nfcr/ocik-^^f^m •

UP

Hsfo^ MxA /^s/on Atocf Arm ex/^ £/^cfy/c-a/' SCALE IN INCHES

AFSR TWO SPEED JACK ASSEMBLY

FIG.9

SECr/OA/ A—A I I I I I

SCALE IN INCHES

AFSR CONTROL ROD DRIVE ASSEMBLY

FIG. 10

U u

I \_^-A^i/A/rwS PLJ^TE

A'sr- rrfie /.OCAT

M/CKOD/AL

SECTION A - A

I I I I I I — r SCALE IN INCHES

AFSR SHIM ROD ACTUATOR ASSEMBLY F I G . 1 1

f\

SAFETY CIRCUIT

SAFETY CIRCUIT

PYROMETERS

REMOTE

AREA MONITORS

LINEAR AMPLIFIER

1

ANNUNCIATOR

LINEAR RECORDER

CONTROL

)

P A N E L _ ^

r

1

1

t p

PERIOD METER

PERIOD METER

LINEAR

PULSE AMPLIFIER

1

LOG POWER

a PERIOD

RECORDER

1

START-UP SCALER

NSLOPING)

[CHAMBER VOLTAGE 1 SUPPLY

CHAMBER VOLTAGE 1 SUPPLY

CHAMBER VOLTAGE SUPPLY

CHAMBER VOLTAGE SUPPLY

CHAMBER VOLTAGE SUPPLY

AFSR CONTROL CONSOLE FIG. 12

SAFETY ROD POSITIONS NO. I NO. 2

JACK POSITION CONTROL ROD POSIT ON

DDD DDD

POWER

(KEY) D. C. BLOWER

ON © SLOW SHUTDOWN

RESET ( O F F ) (OFF)

o SAFETY ROD*l SAFETY R0D*2 JACK

t *

SAFETY AIR PLUG

DOWN DOWN AIR UP

o UP

DOWN UP DOWN UP DOWN CONTACT UP DOWN UP

CONTROL ROD

*

SCRAM

o

AFSR CONTROL PANEL FIG.13

55

ION CHAMBER

SAFETY

CIRCUIT NO 1

CHAMBER

VOLTAGE SUPPLY

ION CHAMBER

•^ 1

SAFETY

CIRCUIT NO 2

CHAMBER

VOLTAGE SUPPLY

ION CHAMBER

LOG AMPLIFIER

ION CHAMBER

•^ 1 * LOG

AMPLIFIER PERIOD

METER NO 1

CHAMBER

VOLTAGE SUPPLY

CHAMBER

VOLTAGE SUPPLY

BF, PROPORTIONAL COUNTER

PRE­AMPLIFIER

*

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a H V POWER SUPPLY

ION CHAMBER

LINEAR

AMPLIFIER

CHAMBER

VOLTAGE SUPPLY

LINEAR

RECORDER

FUEL TEMPERATURE THERMOCOUPLE

SYSTEM THERMOCOUPLES

^COOLING AIR EXHAUST

FLOW TRANSDUCER

ION CHAMBER

EFFLUENT ACTIVITY DETECTOR

ION CHAMBER

FILTER ACTIVITY DETECTOR

ION CHAMBER

SUBFILE ROOM ACTIVITY DETECTOR

REMOTE

AREA r

MONITOR

^

0- l60"C CONTACT PYROMETER

\D <SJ

0- l50°C PYROMETER

FLOW METER

EFFLUENT ACTIVITY

RECORDER

AFSR INSTRUMENTATION

FIG. 14

ON

SCALE IN FEET

FIG. 15

CALLED , ( (0V NORTH AIR COMPRESSOR -O

ACCESS TUNNEL-W/ COVER

X I L

HEAT a VENT.-» DUCT

(10'3" OFF FLOOR)

-ROLLING DOOR

REACTOR CORE EXHAUST STACK

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i L I l t l l .

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r-r i-r 'TrTT-n-r i- f FT SCALE IN FEET

SECTION A-A

REACTOR BLDG. LAYOUT

FIG. 16

Ul -vl

00

1—'

2 0 %

56,948 TOTAL HOURS

7o CALM WIND SPEED MPH 7o FREQUENCY

6-15 16-30,^^Q 10

IE 15 T:

20

CENTRAL FACILITIES 20 FOOT LEVEL WIND ROSE \ 1950 THROUGH 1956

FIG. 18

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7.711

SECT/ON A—A

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AFSR BEAM HOLE LINER FIG. 19

4000

3600

2800

iij

< o

2000 o

UJ UJ Q:

UJ

1200

4 0 0

32 TIME, sec

Predic ted behavior of AFSR going cr i t ica l 0.1 inch from fully assembled position at a ra te of 0.0004 Ak/k per second.

FIG. 20

4000

3600

80 TIME.sec

Predicted behavior of AFSR going cr i t ica l 0.3 inch from fully assembled position at a ra te of 0.0004 Ak/k per second.

FIG. 21

u k

- < ;

r

/

/

ADDITION 0 STOPS AT 3

/

- ^

- REACTIVITY 1 0 sec

^ ~ ^ ^ ^ ^ - - - I 2 ^ ^ ^ - - 5 E A C T O R _ _

c o 5 £ ^ ^

-POWER_____

LOG INTEGRATED UNIT

_ C O R E _ _ - ^

POWER

par.F_ TEMPERATURE

• ^

4000

3200

UJ

2400 < a. o I-z UJ

o

UJ

1600 ^ o UJ

o

800

12 16 TIME, sec

20 24 28

P r e d i c t e d b e h a v i o r of AFSR going c r i t i c a l 0.1 i nch from, fully a s s e m b l e d pos i t i on a t a r a t e of 0.003 A k / k p e r s e c o n d .

F I G . 22

00

4000

3200

UJ

o 2400 ^

CD

O

(/) UJ UJ

1600 g Ul o

800

16 TIME, sec

Predicted behavior of AFSR going cr i t ica l 0.3 inch from fully assembled position at a ra te of 0.003 Ak/k per second.

FIG. 23

u

-• S 6

< o

UJ

O x> °- Q:

.< * zi 2^.

S S

o o - I _l

V

J J If - i 1

»i 1 V d-d— o o;

'fjj

1

V

i

% \ -36__LOi i

— r ACTUAL

\

\

u

INTEGRATED J UNIT POWER

INTEGRATED L JNIT POWER —

-

4 0 0 0

3600

2800 UJ o < o H Z UJ

o 2000 o)

UJ Q: CD UJ

a

1200

400

10 12 14 TIME, sec

Predic ted behavior of AFSR going cr i t ica l one inch from fully assembled position at a ra te of 0.03 Ak/k per second.

FIG. 24