Bill WilbornUGTA Activity Lead

U.S. Department of Energy,

National Nuclear Security Administration Nevada Field Office

Bob AndrewsNavarro-Intera

December 10, 2014

Nevada National Security Site Underground Test Area

(UGTA) Tour

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Nevada National Security Site (NNSS)

• NNSS has many diverse roles to

support the U.S. nuclear weapons

stockpile stewardship missions

and also supports other U.S.

Department of Energy (DOE),

Department of Defense, and

Department of Homeland Security

programs

• DOE National Nuclear Security

Administration Nevada Field Office

responsible for oversight

• ~1,360 square miles of federally-owned and

controlled land, surrounded by ~4,500 square miles of

federally-owned and controlled land (U.S. Air Force)

• Located ~65 miles northwest of Las Vegas

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• 1,149 total U.S./

U.S.-U.K. nuclear

detonations

– 1,021 at NNSS

� 100

atmospheric

� 921

underground

• A nuclear test

may include

more than one (1)

detonation

U.S. Nuclear Testing, 1945 – 1992

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0

10

20

30

40

50

60

70

1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995

BANEBERRY: Accidental release of radioactivity detected off site; better site characterization and

containment evaluation resulted

Last U.S. nuclear underground test: DIVIDER

NNSS Nuclear Testing 1951 – 1992C

ou

nt

UndergroundAtmospheric

First NNSS nuclear test:

ABLE

First underground test at NNSS: UNCLE

First detonation contained underground: RAINIER

Last U.S. atmospheric nuclear test at the NNSS: LITTLE FELLER I

DOE/NV, 2000

EMPLACEMENT

D

R

I

L

L

I

N

G

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Log No. 2014-xxx

C

O

L

L

A

P

S

E

C

O

L

L

A

P

S

E

D

C

R

A

T

E

R

S

ACCIDENTAL

RELEASE OF

RADIOACTIVITY

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POST-TEST SAMPLE ANALYSIS

Photographs from

CMS-05-010_JMK, 2005

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Regional Geologic Setting � NNSS lies within the

Southwestern Nevada Volcanic

Field, which includes 8 known calderas that formed between 15 million years ago (Ma)

and 8 Ma

Modified from Drellack and Prothro (2010)

Generalized geologic map showing the outline of the Southwestern Nevada Volcanic Field

Generalized geologic map showing the outline of the Southwestern Nevada Volcanic Field

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Regional Geologic Setting

– Rocks at the NNSS ~ 12,200 m

(40,000 ft) thick and span more

than 500 million years in age

– Diverse depositional

environments and geologic

processes

� Marine clastic and

carbonate deposition

� Volcanic activity

� Igneous intrusion

� Alluvial basin-filling deposition

April 2014 9

Generalized stratigraphic column of the NNSS vicinity

Drellack and Prothro, 2010

Generalized stratigraphic column of the NNSS vicinity

Drellack and Prothro, 2010

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• At the NNSS, contractional

structural events are older than

100 Ma and resulted in

– Thick deposits of Mississippian

siliciclastic rocks

– Formation of thrust faults, and

associated imbricate thrusts

and folds

April 2014 1

NNSS Geologic Setting

Major Pre-Cenozoic structural features of the NNSS regionModified from BN (2006)

Major Pre-Cenozoic structural features of the NNSS regionModified from BN (2006)

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Geologic compilation map of the NNSSWorkman et al., 2002

Geologic compilation map of the NNSSWorkman et al., 2002

Detailed geologic quadrangle mapHinrichs and McKay, 1965

Detailed geologic quadrangle mapHinrichs and McKay, 1965

• Widespread basin-and-range extensional faulting at the NNSS

– Normal and strike-slip faults

– Alluvium-filled basins (e.g., Frenchman Flat

and Yucca Flat)

April 2014 1

NNSS Geologic Setting

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NNSS UGTA Corrective Action Units

• CAU 97: Yucca Flat/Climax Mine –

747 detonations

• CAU 98: Frenchman Flat –

10 detonations

• CAU 99: Rainier Mesa/Shoshone

Mountain – 68 detonations

• CAU 101: Central Pahute Mesa –

64 detonations

• CAU 102: Western Pahute Mesa –

18 detonations

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Frenchman Flat

Geologic Setting

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Frenchman Flat Geologic Cross Section

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• Yucca Flat is an alluvium-filled

basin surrounded by highlands

composed of volcanic and

sedimentary rocks

• Topographically closed basin with

a playa (seasonally dry lake) at its

southern end

April 2014 1

Yucca Flat Geologic Setting

Generalized geologic map of the Yucca Flat areaModified from BN (2006)

Generalized geologic map of the Yucca Flat areaModified from BN (2006)

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• The main Yucca Flat basin consists of a series of

west-tilted half grabens with the main basin-forming faults near

the center of the basin

• Basin began forming approximately 10 Ma in response to

basin-and-range extension

April 2014 1

Yucca Flat Geologic Setting

Modified from BN (2006)