ML20197G015

Forwards Request for Addl Info to Be Transmitted to Util Re Effects of Plant Permanent Dewatering Sys on Liquid Release from Postulated Core Melt Accident

ML20197G015
Person / Time
Site:	Satsop
Issue date:	07/11/1983
From:	Ballard R Office of Nuclear Reactor Regulation
To:	Knighton G Office of Nuclear Reactor Regulation
References
CON-WNP-1277 NUDOCS 8307250056
Download: ML20197G015 (4)

Text

-,

i

{

t DISTRIBUTION:

/ Dockets EHEB Rdg JUL 111983 RLBallard Docket !!o. 50-508 MELIORAllDUM FOR: George Knighton, Chief Licensing Branch !!o. 3, DL FROM: Ronald L. Ballard, Chief Environmental & Hydrologic Engineering Branch, DE SUDJECT: HYDROLOGIC ENGINEERING E!!VIRONME; ITAL QUESTION l

Plant Hace: tiashington Public Power Supply Systen Nuclear Project No. 3 (UNP-3)

Licensing Stage: OL

Responsible Branch

Licensing Branch !!o. 3, A. Vietti, PM The applicant in responding to one of our previous environmental questions concerning the consequences of a liquid release from a postulated core-nelt accident, did not address the effects of the plant's pemanent dewatering system. Since the dewatering system is a passive one without punps or valves that can be used to deactivate the system, it is likely that contaminated groundwater will be intercepted by the dewatering system and released to the surface in a much shorter tice and at greater concentrations than estinated by the applicant.

1 In order for us to address this concern, we need additional infomation. The f attached question, for your transmittal to the applicant, was preoared by s R. Gonzales who can be reached on extension 20018.

l Gr@u. : ; am L edi, ara

( Ronald L. Callard, Chief

{ Environmental & Hydrologic

$ Engineering Branch

& Division of Engineering i

[

Attachment:

As stated j cc: Seo wrt oage 7250056 8307112(

W ADOCK 05000508

/C ih L0a

"'"*DE:EHEB.h..0E;EHEB.. .0E:ENEB. .0E:EH .h.f .... . . .

"*"*RGonzaleViwsL..RCodell

, .f.. MEl iegel .  ! ..RLBallarYi ..h. l ..

"""l7/8/83.. . 7///g3 l.7/jl/83.. ..[.. 7/ /I./83 . . ... .i.. . q. .

rme roav na no-acmeu ovo OFFICIAL RECCRD COPY

/

• g .3- 1 George Knighton t 11 &3

. cc: w/o attachment R. Vo11 tier T. Movak w/ enclosure W. Johnston L. Hulman A. Vietti M. F11egel R. Codell '

R. Gonzales on,es y ....... .. ....... .. .. ........ .. ............ . .. . . .. . .. . ... . . . .. ..

su m uck .................. ....... . .... ..... .. ........ . .. . .. .. ... . . . . . . ...

ears) ........ . ...... ...... ............ .......... . ........ .. .. .. .. .. . . ... ... . . ..... . . . . . . . . . . . . . . .

. ~ae ror= 2i. . io- o , r.ac"

OFFICIAL RECORD COPY ,

. ~ . __ _

m; ,~

\

~

. Hydrologic Engineering Environmental Question WNP-3 240.14 In response to our previous question 240.13, you provided an (ER) analysis of the radiological consequences of a liquid pathway - t release from a postulated coreceit accident. In that analysis you assumed that, following base mat penetration there would be contamination of the groundwater whose gradient and monment is northward toward the Chehalis River.

Because WNP-3 has a passive (gravity flow) dewatering system, we conclude that it is likely that contaminated groundwater would

^

be intercepted by the dewatering system and carried southward  :

to Workman Creek instead of northward as you have assumed.

1. Interception by the dewatering system would result in contani-nants entering the Chehalis River much more rapidly and in. greater concentrations than you have calculated. You should therefore provide a detailed discussion and analysis cf the effects of the dewatering system on the liquid pathway release from a core-nelt .

accident.

If, based on your reanalysis, you still conclude that cortaminated -

groundwater will move northward to the Chehalis River and will not be intercepted by the dewatering systea, you should provide the i basis for your conclusion, including all pertinent assumptions.

If you conclude that a core-melt accident will destroy the dewatering system to the extent that it doesn't fur.ction even partially, you should describe how the core-melt will affect each portion of the dewatering system, i.e., the collector and half-round pipes, the perforated underdrains, the manholes and the drainage tunnels including the corrugated metal pipes inside the drainage tunnels. You should also address the potential for '

the core-melt to open new pathways to the dewatering system an'd/or to Workman Creek. In addition, you should provide the folicwing infomation:

a) The value of permeability that you selected, 2.08 x 10-3 cm/sec, is the highest value deter nined using a Packer test in boring A-35 which is located in sandstone to the west of RAB-3. Since a spill to groundwater would move toward the north-northwest (if not intercepted by the dewatering system), it is questionable whether this permeability value would be applicable. Borings to the north-northwest of RAB-3 (Borings A-2, A-17 and A-45) show that groundwater novement would be mostly through sands and silty sands and not through sandstone as you assuned. Since the permeability of sands and silty-sands is generally several orders of i

S

y

• s ,

r

,b -

magnitude greater than the permeability of sandstone, the movement of contaminated groundwater could.be much more rapid than the 1938 years you calculated. You should therefore recompute travel time using the appropriate permeability for the soils located north-northwest of the plant unless you can show that 2.08 x 10-5 cm/sec is a conservative estimate of that permeability. -

b) Explain how you determined a porosity of 0.35. In computing travel time, you should use effective porosity rather-than total porosity. Generally the. effective porosity of sandstone ranges from about .10 to .20. For sand and silty sand such WP as found to the north-northwest of RAB-3, a value of 0.35 appears to be a reasonable estimate.

O e

k

- 81 k

k e

.%