ML20035B102

Advises That NRC Working W/Doe Contractor (MK-Ferguson Co) to Evaluate Permeability of Base of Disposal Cell for Rifle, Co Site.Test Results Raised Concern Re Potential for Long Term Moisture Accumulation in Disposal Cell

ML20035B102
Person / Time
Issue date:	03/01/1993
From:	Surmeier J NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS)
To:	Chernoff A ENERGY, DEPT. OF
References
REF-WM-62 NUDOCS 9303310131
Download: ML20035B102 (2)

Text

-_

q

. / "%o,i f

j s

3" UNITED STATES 3

E NUCLEAR REGULATORY COMMISSION l

WASHINGTON, D.C. 20S56 i

....+

MAR 1 H93 t

Mr. Albert R. Chernoff, Project Manager j

Uranium Mill Tailings Remedial Action Project Office t

U.S. Department of Energy Albuquerque Operations Office P.O. Box 5400 Albuquerque, New Mexico 87115 y

Dear Mr. Chernoff:

~

l We have been working with your Project Manager, Sharon Arp,-and your contractor, MK-Ferguson Company, in discussions and review of data associated l

with DOE's further evaluation of the permeability of the base of'the disposal-l cell for the Rifle, Colorado, site. The recent permeability te:;t results from i

the subgrade testing have caused the Nuclear Regulatory Commission staff.some concern regarding the potential for long-term moisture accumulation in the disposal cell. The preliminary results indicate that the more permeable units -

i ofthysubgrademayexhibitameasuredpermeabilityofonlyabout 4

2x10' cm/sec, rather than the 1x10 cm/sec value previously anticipated by the Department of Energy (DOE). As you are aware, the NRC staff not prepared to accept soil cover permeability of less than lx10'penerally is-cm/sec l

without field verification through test fills. The NRC. staff is concerned j

that there is a realistic likelihood that the cover infiltration flux could

~

ultimately exceed the outflow flux through the bottom of the disposal cell, given the margin of error associated with both the subgrade testing and the

~ future cover construction. This situation could adversely impact the long-term stability of the disposal cell.

1 The NRC staff is concerned that sufficient conservatism is not incorporated-into the design to compensate for the inherent variations that can be i

experienced during cover construction. We would prefer to have an order of

.i magnitude difference between the two permeabilities to be conservative.

However, if the design and construction of the cover is implemented with strict quality control and confirmatory as-built testing, we would be prepared to accept an analysis that demonstrates 'a permeability difference of one-half.

{

an order of magnitude.

This issue, and the NRC staff's present position, should be taken into l

consideration in DOE's actions at the Rifle site in-the immediate future.

We will continue to work closely with your staff to reach a satisfactory.

solution to this problem that provides the level of assurance needed to protect public health and safety and the environment.

1 310057 yn p QVy l

WN 9303310131 930301

{

PDR WASTE WPf-62 PDR

i Albert R. Chernoff 2

-If you have any questions' regarding these comments, please feel free to.

contact me at FTS 8-301-504-3439 or the NRC Project Manager, Allan Mullins at l

FTS 8-301-504-2578.

~

i GlltMED) JOHN J. SdRSElG John J. Surmeier, Chief.

Uranium Recovery Branch j

Division of Low-level Waste Management

'I and Decommissioning-Office of Nuclear Material Safety and Safeguards MiFkT5iill?B6ksE is?C6EUFfiWilB16ckE6Difiiis? Distfibifi6hTC6pilffifeEsn47 i

~ In siall" Box 'on^*0FC:" 11he'enterT'C"'TC'6veF ETCoVeFT Encf6sure NT No" Copy'

^

~

]

0FC LLUR i,

ALURs

'C LLUR C

pm NAME AMullins/eb

./eDGillen JSurM/r o

DATE J// /93 H

b' / / /93 3 // [93 '

/ /93

[

H S:\\LLWMTYPE\\EDIE\\RFLPERM. alm OFFICIAL RECORD COPY In small Box on "DATE:" line enter: M = E-Mail Distribution Copy H'- Hard Copy PDR : YES

/s NO Category:

Proprietary or CF Only ACNW: YES A NO Delete file after distribution Yes No

{

IG: YES NO x__

-i DISTRIBUTION: CNt'raif5IN. LLWM r/f RBangart-

'WBrach-JAustin PLohaus NMSS' r/f ~ ~ LJCallan,RIV RHall,URFO-MFliegel i

f i

z t

i I

l l

-. =

m.

Albert R. Chernoff 2

If you have any questions regarding these comments, please feel free _ to contact me at FTS 8-301-504-3439 or the NRC Project Manager, Allan Mullins at FTS 8-301-504-2578.

StKED) JGKN 1. SURMSE.R '

John J. Surmeier, Chief Uranium Recovery Branch Division of low-Level Waste Management and Decommissioning l Office of Nuclear Material. Safety and Safeguards Nn,g!$isil1[7B6 sit.E, lh? CohEEFihERB16EkW Dif fE.EDiiffMUfi 65%pff Pri.3f0Eh.Ee3:

k g

g

(

g3 0FC LLtJR C,

A LAHb G

LLUR C

NAME AMullinsNb

/eD(fiYlen JSur M DATE. J // /93 h k/ / /93 3 // [93

/ /93-H S:\\LLWMlYPE\\EDIE\\RFLPERM.ATM OFFICIAL RECORD COPY In small Box on "DATE:" line enter: M = E-Mail Distribution Copy H = Hard Copy PDR : YES A

NO Category: ' Proprietary or CF Only ACNW: YES A NO Delete file after distribution Yes No IG: YES NO v DJSTRIBUTION: b$nkal57I15$4 LLWM r/f RBangart WBrach JAustin PLohaus NMSS r/f '~

~LJCallan,RIV RHall,URF0 MFliegel i

>