ML17285A864

Discusses 891109 Telcon Re Unreviewed Safety Question Re Standby Gas Treatment Sys.Engineering Analyses Ongoing to Determine Suitable Modeling Techniques & Assumptions That Will Be Used to Establish Revised Design Basis

ML17285A864
Person / Time
Site:	Columbia
Issue date:	11/30/1989
From:	Sorensen G WASHINGTON PUBLIC POWER SUPPLY SYSTEM
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
GO2-89-216, NUDOCS 8912070336
Download: ML17285A864 (7)

Text

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ACCESSION NBR:8912070336 DOC.DATE: 89/11/30 NOTARIZED: NO DOCKET FACIL:50-397 WPPSS Nuclear Project, Unit 2, Washington Public Powe 05000397 AUTH. NAME AUTHOR AFFILIATION SORENSEN,G.C. Washington-Public Power Supply System RECIP.NAME RECIPIENT AFFILIATION Document Control Branch (Document Control Desk)

SUBJECT:

Discusses 891109 telcon re unreviewed safety question re standby gas treatment sys.

DISTRIBUTION CODE: AOOID TITLE: OR COPIES RECEIVED:LTR Submittal: General Distribution L ENCL 2 SIZE NOTES:

RECIPIENT COPIES RECIPIENT COPIES ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL PD5 LA 1 1 PD5 PD 1 1 SAMWORTHPR 5 5 INTERNAL: ACRS 6 6 NRR/DET/ECMB 9H 1 1 NRR/DOEA/OTSB11 1 1 NRR/DST 8E2 1- 1 NRR/DST/SELB 8D 1 1 NRR/DST/SICB 7E 1 1 D.

NRR/DST/SRXB 8E 1 1 NUDOCS-ABSTRACT 1 1 OC B 1 0 OGC/HDS2 1 0 REG PILE Ol 1 1 RES/DSIR/EIB 1 1 EXTERNAL: LPDR 1 1 NRC PDR 1 1 NSIC 1 1 8

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TOTAL NUMBER OF COPIES REQUIRED: LTTR 27 ENCL 25

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~ Vr WASHINGTON PUBLIC POWER SUPPLY SYSTEM P.O. Box 968 ~ 3000 George Washington Way ~ Richland, Washington 993S2 November 30, 1989 G02-89-216 Docket No. 50-397 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D.C. 20555 Gentlemen:

Subject:

NUCLEAR PLANT NO. 2, OPERATING LICENSE NPF-21 UNREVIEMED SAFETY QUESTION REGARDING STANDBY GAS TREATMENT (SGT) SYSTEN

Reference:

Letter, G02-89-176, GC Sorensen (SS) to NRC, same subject, dated September 29, 1989 On November 9, 1989 a telephone conference call was held with the NRC staff (R.

Samworth and J. Kudrick) concerning the Supply System's justification for continued operation (JCO) pending the reanalysis of the secondary containment transients and attendant dose calculations. As a result of that conference call, the Supply System agreed to provide further information on the following two issues:

1) In the reference letter, the Supply System provided a JCO but did not describe a plan for final resolution of the identified issue. The Supply System was requested to address this plan in further detail.

2) The Supply System was asked to provide further information to document leak tightness of secondary containment and assure that major repairs have not been required to meet leak test criteria.

The purpose of this letter is to address these items.

Regarding the first issue, WNP-2 is currently evaluating possible long-term solutions to resolve the US( identified in the referenced letter. Engineering analyses are ongoing to determine suitable modeling techniques and assumptions .

(e.g. wind, temperature, SGTS flow and secondary containment leakage) that will be used to establish a revised design basis to provide assur ance the 10CFR 100 and General Design Criterion 19 guidelines and criteria are satisfied.

Pool 8912070336 89ii30 PDR *DOCK; 05000397 p PNU

'I Page Two UNREVIEWED SAFETY QUESTION REGARDING STANDBY GAS TREATMENT (SGT) SYSTEM WNP-2 plans to have outlined the necessary information to justify assumptions and design bases by January 15, 1990. As discussed, WNP-2 will then seek to meet with NRC personnel to discuss the acceptability of these assumptions and potential long-term solutions. Our goal for this meeting would be to obtain preliminary NRC concurrence with our long-term solution path prior to committing extensive resources toward developing a 'revised design basis and resolution of this USQ.

The following subject areas are expected to be a part of the long term solution:

~ Suppression pool scrubbing credit per SRP 6.5.5 Rev. 0

~ SGT rated flow rate

~ Allowable secondary containment leakage

~ Heteorological probabilities of temperature and wind

~ SGT post accident (credit for iodine removal)

~ Compliance to Reg. Guide 1.52

~ Service water temperature effects

~ Post-LOCA heat load effects

~ Potential revised high energy line break (HELB) design basis

~ Control room habitability criteria

~ Offsite dose criteria

~ Technical Specification changes Regarding the second issue, secondary containment leakage has been verified each year since plant startup. The test procedure acceptance criteria are based on Technical Specification parameters and do not require recording of actual values.

Three data points are available to evaluate in-leakage of secondary containment following the reactor building roof rupture event. In all sur veillances to date, the Technical, Specification criteria were met.

WNP;2 has not had to make repairs in order to maintain secondary containment leakage values. Normal maintenance programs and penetration surveillances have identified only three minor leakage deficiencies, and each repair subsequently reduced secondary containment in-leakage. Thus, secondary containment leakage rate appears to be stable and improving.

4 wr Page Three UNREVIEWED SAFETY QUESTION REGARDING STANDBY GAS TREATMENT (SGT) SYSTEH The following chronologically lists the results of tests where test data were recorded and identifies dates when repairs were made that reduced leakage. All other values were taken during execution of the Standby Gas Treatment Functional Test procedures by the system engineer.

June 1985 Leakage recorded at 1800 CFH 8 -.30"wg Hay 1988 Reactor Building roof event Hay 1988 Leakage at < 2240 CFM 8 -.37"wg. Surveillance verified secondary containment integrity.

Sept. 1988- Two (2), four (4) inch penetr ations were identified and seal ed.

Dec. 1988 Leakage recorded at 2183 CFH 8 -.37"wg (1475 CFH stand ardized)

June 1989 Seals replaced on all Reactor Building HVAC intake and exhaust valves.

Sept. 1989- Leakage recorded at 2185 CFH 8 -.44"wg (1228 CFH standardized)

These data indicate that secondary containment integrity has been improved since 1985 due to the repair efforts listed. The data indicate that performance of the secondary containment boundary has been stable. The in-leakage stated in the JCO is based upon current data. Changing of surveillance frequency is typically based upon test failures. Test failures have not been experienced and data are insufficient to conclude a frequency change is necessary. The repairs mentioned above can be expected to result in stable in-leakage for at least five years based upon the qualified life of the REA/ROA valve seals. R-5 outage will occur approximately nine months after the September 1989 test. The current Technical Specification test frequency is 18 months. The Supply System does not believe that any additional increase in the testing frequency is necessary.

Very truly yours, g.~ C. Sorensen,

~ Manager Regulatory Programs HLA/bk CC: JB Hartin - NRC RV NS Reynolds - BCP8R RB Samw'orth - NRC, DL Williams - BPA/399 NRC Site Inspector - 901A