MIAR u 7 1890 89001010

STEIN 3/1/90- I -

Mr. Ralph Stein, Associate Directorfor System Integration and Regulations

Office of Civilian Radioactive Waste ManagementU.S. Department of Energy, RW-30Washington, D.C. 20545

Dear Mr. Stein:

The purpose of this letter is to transmit the summary for the February 6-7, 1990NRC-DOE Technical Exchange on Hydrogenic Deposits. NRC and DOE discussed thepreliminary results of activities directed toward the identification andcharacterization of the hydrogenic deposits at Trench 14, Busted Butte, andother localities in the vicinity of Yucca Mountain and then visited a number offield localities to examine various kinds of hydrogenic deposits in the areaand to see the field evidence relating to those deposits. Representatives ofthe State of Nevada attended this interaction, and a representative from theState introduced information based upon recent field and laboratory workrelating to Yucca Mountain hydrogenic deposits.

Should you have any questions on(FTS 492-0446) of my staff.

the enclosure, please contact King Stablein

Sincerely,

John J. Linehan, DirectorRepository Licensing and QualityAssurance Project Directorate

Division of High-Level Waste Management

Enclosure: As stated

cc: R.C.S.M.D.

- K.

Loux, State of NevadaGertz, DOE/NVBradhurst, Nye County, NVBaughman, Lincoln County, NVBechtel, Clark County, NVTurner, GAO

DISTRIBUTION

U)Q. Central File

LSSCNWRALPDRT. Cardone

B.J. YoungbloodJ. LinehanNMSS R/FACNWr. ToQtfV

R.E. BrowningR. BallardHLPD R/FPDR

J. BuntingOn-Site RepsK. StableinJ. Bradbury

OFC : HLPD : HL

NAME: # n/ll : Jtia :

Date: 3/DU/90 : 3/1/90 :

t11r -

SUMMARY OF NRC-DOE TECHNICAL EXCHANGEON HYDROGENIC DEPOSITS

Las Vegas, Nevada (February 6, 1990)Field Trip Localities In the Vicinity ofYucca Mountain, Nevada (February 7, 1990)

Agenda: See Attachment 1.

List of Attendees: See Attachment 2.

Summary:

On February 6-7, 1990, the U.S Nuclear Regulatory Commission (NRC) and the U.S.Department of Energy (DOE) conducted a technical exchange on hydrogenicdeposits in the vicinity of Yucca Mountain, Nevada. The objective of thetechnical exchange was to discuss preliminary results of activities directedtoward the identification and characterization of the hydrogenic deposits atTrench 14, Busted Butte, and other localities near Yucca Mountain. On February6, various DOE investigators led discussions on the results of various lines ofevidence that are being factored into an understanding of the origin andsignificance of the hydrogenic deposits. Preliminary conclusions based uponthe ongoing Trench 14 studies were presented by DOE at the end of the day(Attachment 3). On February 7, the group visited a number of sites in thevicinity of Yucca Mountain in order to examine various kinds of hydrogenicdeposits in the area and to see the field evidence relating to these deposits.The State of Nevada participated in the exchange and introduced informationbased upon its field and laboratory studies relating to the hydtogenicdeposits (Attachment 4).

Both NRC and DOE considered that the exchange promoted a better understandingof the range of models that could account for the Yucca Mountain hydrogenicdeposits and which models are most strongly supported by the currentlyavailable results from DOE's stydies. In addition, useful discussion occurredwith regard to the need to recognize when to bring an activity to an end, i.e.,when further investigations appear unlikely to substantially reduce theuncertainty in the understanding of some aspect of the site.

/f wQ/Stablein, Sr. Project na er Steven H. RossiR sitory Licensing and Quality Licensing Branch

Assurance Project Directorate Office of Civilian RadioactiveDivision of High-Level Waste Management Waste ManagementU.S. Nuclear Regulatory Commission U.S. Department of Energy

IAttachment 1

AGENDA

DOE-NRC TECHNICAL EXCHANGE ON CALCITE-SILICA VEIN DEPOSITS

FEBRUARY 6 AS 7, 1990, LAS VEGAS, NVROOM 450, SAIC OFFICES - VA&LLEY BmNK CENTER

Tuesday 8:00 a.m. - 5:30 p.m.Wednesday 7:00 a.m. - 6:30 p.m. (field trip)

PURPOSE: To discuss preliminary results of activities directed toward the

identification and characterization of hydrogenic deposits in the

vicinity of Yucca Mountain. Such information is important in theevaluation of future performance of a geologic repository beneathYucca Mountain.

SCOPE: This technical exchange will concentrate on topics related to thepreliminary efforts of hydrogenic studies primarily at Trench 14 andBusted Butte. The discussions on Tuesday will address results of

previous and current work, possible analogs, analytical techniquesthat may be applicable to the studies, and future plans. The fieldtrip scheduled for Wednesday will provide an opportunity forparticipants to examine these and other hydrogenic deposits nearYucca Mountain.

Tuesday, February 6, 1990

A sElm TOPICS DISCUSSION LEADER

Opening remarks DOE, NRC, State

o Background and SCP setting DOE

o Field studies of laminated, authigenic DOEdeposits and soils and development ofworking hypothesis for origin at Trench 14

Discussion all

o Results of chemical and mineralogical studies DOE- of laminated deposits in faults:

- Trench 14 and Busted Butte vein deposits- possible analog sites (hot and cold

spring deposits)

Discussion all

1

Tuesday, February 6, 1990(continued)

AGEDA TOPICS

o Microfossil studies:

- ostracodes- chrysophytes

Discussion

o Stable isotope studies

Discussion

o Tracer isotope studies:

- principles of radiogenic isotope systems- strontium isotopes in Yucca Mountain

studies and regional ground-water systems- preliminary lead isotope results for Yucca

Mountain studies- use of U-series isotopes in tracer studies

Discussion

o Geochronology of hydrogenic deposits

Discussion

o Breccia studies:

- petrology of breccia types- geochronology related to breccias

DISCUSSION LEADER

DOE

all

DOE

all

DOE

all

DOE

all

DOE

Discussion

o Conclusions regarding preliminary work, includingpaleohydrologic implications and future plans

- Discussion

Closing remarks

Field trip plans

Adjourn

all

DOE

all

DOE, NRC,

DOE

State

2

Wednesday, February 7, 1990

Field Trip to Hydrogenic Deposits in the Yucca Mountain Area

Morning:

Stop 1

Stop 2

Stop 3

Lunch

Afternoon:

Stop 4

- Calcite-silica veins and other deposits at Trench 14

- Soil and fault in-fillings at Trench 16

- Calcite-silica veins and other deposits at Busted Butte

- Calcite and/or travertine deposits at Site 106 on Stagecoach Roadsouth of Yucca Mountain

- Travertine deposits in south Crater Flat

- Possible marsh deposit at "Horse Tooth" site

Stop

Stop

5

6

Note: Will leave Las Vegas for the site at 7:00 a.m.; Expect to return to LasVegas by 6:30 p.m.

3

Attachment 2

ATTENDANCE LIST

NRC/`DOE TECHNIC&L EXCHANGE CN CA~LCITE-SILICA VEIN DEPOSITSFebruary 6, 1990

Valley Bank Building101 Convention Center DriveLas Vegas,, Nevada 89109

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NRC/DOE TECHNICAL EXCHANGE ON CALCITE-SILICA VEINMDEPOSITSFebruary 6, 1990

Valley Bank Building101 Convention Center DriveLas Vegas, Nevada 89109

NAME

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Attachment 3

DRAFTCONCLUSIONS

(FOR TRENCH 14 EFFORTS)

(1) THERE ARE CARBONATE HORIZONS THAT PISSI CALLY ANDMORPHOLOGICALLY MATCH PEDOGENIC CARBONATE HORIZONS THROUGHOUTTHE WORLD. ?bBILIZATION OF CARBONATE AND SILICA INTO VERTICALVEINS BY THE SAME MECHANISM THAT FORM THE lORIZONTAL LAYERSPROVIDES THE MIST REASONABLE WAY TO FORM THE VEINS AT TRENCH 14.

(2) THE MINERALOGY AND CDEMISTRY OF THE VEINS MATCH THOSE OFPEDOGENIC DEPOSITS. THE MICRO-SITE DISEQUILIBRIUM ARGUES AGAINSTFORMATION IN A SATURATED ENIROENT SUCH AS MIGHT BE EXPECTED NEARA SPRING ORIFICE. MINERALOGY AND CHEMISTRY CAN AND WILL BE USEDTO INSURE THAT ALL PARTS OF THE VEIN FORMED BY A SINGLE MECHANISM.

(3) THE APPARENT LACK OF OSTRACODE S ARGUES AGAINST AN ENVIRONMENTWITH STANDING WATER FOR PERIODS OF 3 PLINTHS OR MORE AS MIGHT BEEXPECTED AT A SPRING DISOJARGE SITE.

(4) THE PRESENCE OF RARE CHRYSOPHYTE CYSTS SUGGESTS FORMATIONBY DILUTE WATERS SUCH AS THOSE THAT WOULD EXlST AT AN EPHEMERALRECHARGE SITE AND ARGUE AGAINST EVEN AN EPHEMERAL DISCHARGE SITEFOR DEEP SEATED GROUNDWATERS.

(5) CARBON AND OXYGEN ISOTOPIC COMPOSITIONS OF THE VEINS MATCHWELL WITH THOSE FOR PEDOGENIC CARBONATES, AND THE 61'O VALUESARE CONSISTENT WITH PRECIPITATION OF CALCITE FROM MODERN METEORICWATERS AT REASONABLE NEAR-SURFACE TEMPERATURES. CONVERSELY, 6 .OVALUES FOR THE VEIN CARBMNATES ARE HEAVIER THAN THOSE THAT WOULDFORM IN EQUILIBRIUM WITH CURRENT GROUNDdATERS AT THEIR PRESENT-DAYTEMPERATURES.

(6) STRONTIUM ISOTOPIC COMPOSITIONS OF THE VEINS ARE MUCH FORERADIOGENIC THAN WATERS IN EQUILIBRIUML WITH THE PALEOZOIC CARBONATESAND MORE RADIOGENIC THAN ANY OF THE WATERS ANALYZED THUS FAR FROMBENEATH YUCCA MbuNTAiN. THE VEINS ARE LESS RADIOGENIC THAN THEHOSTING VOLCANIC ROCKS BUT ARE NEARLY IDENTICAL IN ISOTOPICCOMPOSITION TO PEDOGENIC CARBONATES IN THE VICINITY OF TRENCH A4.

(7) THE 234U/"'U RATIOS IN GROUNDWATERS OF SOUTHERN NEVADA ANDVEINS FORMED FROM THOSE WATERS DURING THE LAST 600 KA AREANIXMALOUSLY LARGE (GENERALLY p2.5). THIS IS ESPECIALLY TRUE FORTHE FEW ANALYSES FROM JACKASS FLATS (N4.5). THE CALCITE IN THETRENCH 14 VEINS COULD NOT HAVE FORMED FROM SUCH WATERS BUT THEVALUES OF <1.5 WOULD BE CONSISTENT WITH DOWNWKARD PERCOLATING WATERSOF A PEDOGENIC SYSTEM.

(8) EVIDENCE GATHERED TO DATE DOES NOT YET PROVE A SINGLE MDE OF ORIGINFOR ALL OF THE VEIN CARBONATE AND OPALINE SILICA, BUT NOTHING SUGGESTS

A MULTI-MECHANISM MODE OF ORIGIN.

(9) No SINGLE LINE OF EVIDENCE PROVES A PEDOGENIC ORIGIN. BUT THEWEIGHT OF EVIDENCE OF ALL DATA TAKEN TOGETHER MAKE IT EXTREMELY UNLIKELYTHAT ANOTHER MECHANISM THAT INCORPORATED EXCEPTIONS TO EACH DATA SETCOULD BE FOUNDS

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Attachment 4

INFO itTION PROVIDED BY THE STATE OF 'VADA2500

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