ML20043B035

Staff Requirements Memo Advising That Commission Has Approved Recommendation in SECY-90-120 on Containment Performance Improvement Program for Plants W/Mark Ii,Mark Iii,Ice Condenser & Dry Containments

ML20043B035
Person / Time
Issue date:	05/02/1990
From:	Chilk S NRC OFFICE OF THE SECRETARY (SECY)
To:	Taylor J NRC OFFICE OF THE EXECUTIVE DIRECTOR FOR OPERATIONS (EDO)
References
REF-10CFR9.7 GL-88-20, NUDOCS 9005240105
Download: ML20043B035 (2)

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UNITED STATES

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RELEASED TO ME PDR!

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. OFFICE OF THE SECRET AF1Y

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..........,%??,,,,5 MEMORANDUM FOR:

James M.-Taylor.

Executive Director for Operations AY O.famuel-J..Chilk, Secretary, FROM:

SUBJECT:

SECY-90-120'- RECOMMENDATIONS OF-CONTAINMENT-PERFORMANCE ~ IMPROVEMENT.~ PROGRAM:FOR. PLANTS WITH MARK II, MARK III, ICE CONDENSER, AND=

DRY. CONTAINMENTS This is to advise you that the Commission-(with all Commissioners agreeing) has approved the staff's recommendation in the.subjecto 1

-paper.

Attached is-a suggested revision-.to page 1 of Supplementi-No. 2 of Generic Letter No.-88-20.

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Attachment:

.As stated 1

cc:

Chairman Carr Commissioner Roberts I

Commissioner Rogers.

Commissioner Curtiss Commissioner Remick OGC

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NOTE:

THIS SRM AND THE SUBJECT SECY PAPER WILL BE MADE, PUBLICLY AVAILABLE'IN.10 WORKING' DAYS FROM THE DATE OF THIS SRM

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ALL LICENSEES HOLDING OPERATING LICENSES AND CONSTRUCTION PERMITS FOR NUCLEAR POWER REACTOR FACILITIES-

SUBJECT:

COMPLETION OF. CONTAINMENT-PERFORMANCE IMPROVEMENT PROGRAN AND-

-FORWARDING OF INSIGHTS FOR USE IN THE INDIVIDUAL PLANT EXAMINATION FOR SEVERE ACCIDENT VULNERABILITIES l-GENERIC LETTER N0._88-20, SUPPLEMENT NO.~ 2:

This. letter announces-the completion.of the NRC staff's Containment-.

-Performance Improvement.(CPI)-program. 1 Technical insights-arising from this

. effort for PWR containments and for BWR Mark II: and Mark III containments:are being forwarded via this -letter for use in licensee-efforts as part of the.

' Individual Plant Examination (IPE) effort described in Generic Letter 88-20.

No regulatory requirements have resulted from the CPI-program for these containment types.

Similar technical'information for BWR-Mark I cor+-

nents

-was-diseussed in SECY 89-017, " Mark I Containment Performance Impro Program", dated January 23, 1989, and summarized in an enclo:ure to L..eric Letter 88-20, Supplement-1, dated Auoust 29,: 1989. : ' The' technica14 information

_ A{q, may be useful to licensees during their examinations of their plants for.

vulnerabilities to severe: accidents.

Four specific insights are believed by the staff to be important enough-to k

bring to the attention of licensees for use as. they determine appropriate in N

the IPE for' the plant types to which they apply.

These insights are briefly i

sumarized below. ' As final technical reports providing' additional detail-are

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)ublished, they will ha =ada available to a' licensees.J Licensees should.

) ear in mind-that the insights listed berow are. not all ? inclusive > and. unique--

l plant features may exist that also. warrant ctasideration in the IPE. L.censee:

skesel teu rch 4.c pouil,le ".Jvt.ers " ht.m3htde.Wssed usent a. sysb mark u containments seara w og, g j g.g.

For events:where inadequate containment heat. removal _could.cause core. -.

.2 degradation, additional containment-heat removal capability using plant-specific hardware procedures is expected to be considered as'part of the IPE process. Potential methods of removing heatifrom containment include, but are not limited to, using a4 hardened vent or other means of improving reliability of suppression pool cooling.

It is expected that the negative as well as the positive benefits of the enhanced containment heat _ removal capability will be considered. For example,-

for those events where venting is initiated after core melt and -

subsequent vessel-failure ~haire occurred, the benefit of scrubbing of fission products can not'be an ured for Mark 11 containments to the'same degree as in Mark I plants. LTh?s'is because. molten core-materials on the ficor of the containment may fail downcomers -or drain lines' and result-in suppression pool bypass.

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