ML20216F886

Informs That During 464th & 465th ACRS Meetings on 990714-16 & 0901-03,respectively,Committee Discussed 990622 Response to on Mods Proposed by WOG to Core Damage Assessment Guidelines & Post Accident Sampling Sys

ML20216F886
Person / Time
Issue date:	09/17/1999
From:	Powers D Advisory Committee on Reactor Safeguards
To:	Travers W NRC OFFICE OF THE EXECUTIVE DIRECTOR FOR OPERATIONS (EDO)
References
ACRS-R-1853, NUDOCS 9909240230
Download: ML20216F886 (2)

Text

j##% UNITED STATES

~

f 4 NUCLEAR REGULATORY COMMISSION PDR 1

ADVISORY COMMITTEE ON REACTOR SAFEGUARDS WASHINGTON, D.C. 20585 0001

\*****

September 17,1999 Dr. William D. Travers Executive Director for Operation.s U.S. Nuclear Regulatory Commission Washington, DC 20555-0001

SUBJECT:

MODIFICATIONS PROPOSED BY THE WESTINGHOUSE OWNERS GROUP TO THE CORE DAMAGE ASSESSMENT GUIDELINES AND POST ACCIDENT SAMPLING SYSTEM (PASS) REQUIREMENTS During the 464* and 465* meetings of the Advisory Committee on Reactor Safeguards, July 1416 and September 1-3,1999, respectively, we discussed your June 22,1999 response to our May 19,1999 letter on the subject matter. Your letter included the following comments:

(1) . "The staff . . . Intends to allow options other than PASS samples (such as the use of specific gamma monitors) to provide information regarding the disposition of fission products."

(2) . . . the staff concludes that, for plants with passive pH control or that ere not subject to contamination of the sump with brackish water, pH measurement is not needed because, in these plants, pH will either be maintained alkaline or could be estimated

' with a sufficient degree of accuracy."

Because we disagree with both of these positions, we are clarifying our original recommendations.

With respect to Comment (1) above, our view is that the Post Accident Sampling Systems implemented in the Westinghouse plants do not meet the intent of TMI Action Plan Requirement II.B.3, as specified in NUREG-0737, to have direct and timely information

. regarding "certain radionuclides in the reactor coolant and containment atmosphere that may be indicators of the degree of core damage. . . ." Such intent could be satisfied by the use of specific gamma monitors installed in containment that are tuned to the isotopic gamma

emissions of cesium and krypton. If Requirement ll.B.3 for timely and radionuclide-specific information.is no longer necessary, it should be removed rather than circumvented. If this requirement is retained, then the staff should consider a compliance backfit for the installation of such gamma monitors.

l

.m e

_99o9240230 990917 h ) bs j PDR ACRS R-1853 PDR f

. 2

]

With respect to Comment (2), we disagree with the assertions regarding assurance of maintenance of containment sump alkalinity by passive pH control. The sources of acidic materials during severe accidents are very uncertain and may not have all been identified. In addition, the evaluation of sump alkalinity would be complicated by the need to quantitatively assess complexation, adsorption, and precipitation of buffers by materials introduced into the sump water over the course of an accident. Passive pH control cannot be assessed with sufficient accuracy to assure that an adequate level of alkalinity is maintained over the desired period of time. A direct measurement is needed for appropriate post-accident decisionmaking.

Therefore, we repeat our original recommendation that pH measurement continue to be required for all sumps.

Sincerely,

\ pea W Dana A. Powers Chairman

References:

1. Letter dated June 22,1999, from William D. Travers, Executive Director for Operations, NRC, to Dana A. Powers, Chairman, ACRS,

Subject:

Modifications Proposed by the Westinghouse Owners Group to the Core Damage Assessment Guidance and the Post Accident Sampling System Requirements.

2. Letter dated May 19,1999, from Dana A. Powers, Chairman, ACRS, to William D.

Travers, Executive Director for Operations, NRC,

Subject:

Modifications Proposed by the Westinghouse Owners Group to the Core Damage Assessment Guidelines and the Post Accident Sampling System Requirements.

3. U. S. Nuclear Regulatory Commission, NUREG-0737," Clarification of TMl Action Plan Requirements," dated November 30,1980.

I I

l

\

i

,