ML20209E037

Forwards Auxiliary Sys Branch Response to Allegation 1545, Per Request.Concerns Expressed in Allegation Not Significant to Safety,Based on Reviews in Area of Subcompartment Environs Resulting from Postulated High Energy Pipe Breaks

ML20209E037
Person / Time
Site:	Diablo Canyon
Issue date:	03/05/1985
From:	Rubenstein L Office of Nuclear Reactor Regulation
To:	Novak T Office of Nuclear Reactor Regulation
Shared Package
ML17083B484	List: ML20209C687 ML20209C692 ML20209C725 ML20209C729 ML20209C734 ML20209C742 ML20209C774 ML20209C779 ML20209C786 ML20209C810 ML20209C853 ML20209C869 ML20209D170 ML20209D204 ML20209D416 ML20209D421 ML20209D450 ML20209D560 ML20209D649 ML20209D703 ML20209D864 ML20209D903 ML20209E021 ML20209E030 ML20209E037 ML20209E052 ML20209E145 ML20209E211 ML20209E268 ML20209E506 ML20209F952 ML20209G177 ML20210E664 ML20210E745 ML20210E799 ML20210E811 ML20210E916
References
FOIA-86-197 NUDOCS 8503130099
Download: ML20209E037 (3)

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NUCLEAR REGULATORY COMMiSFIDH WASHING TON, D. C. 20S55

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m 3 ;m ORANDUM FOR: Thomas M. Novak, Assistant Director for Licensing, Division of Licensing FROM: L. S. Rubenstein, Assistent Director for Core and Plant Systems, Division of Systems Integrat'on

SUBJECT:

RESPONSE TO DIABLO CANYON ALLEGATION NO. 1545, AVAILIARY '

SYSTEMS BRANCH '

Enclosed as requested by DL is the Auxiliary Systems Branch's response to Diablo Canyon allegation No. 1545. We have concluded based on our previcus reviews in the area of subcompartment environments resulting from postulated high energy pipe breaks outside containment, that the concerns expressed in the allegation are not significant to safety and the licensee.need take cdi further action in this regard.

In addition, we are also enclosing a previous response dated July 17, 1984 to what appears to be the same allegation which was prepared by the Containment Systems Branch.

O (' ..Lu.. k L. S. Rubenstein, Asristant Director +

for Core a:td Plant Systems Division of Systems Integratior

Enclosure:

As Stated ,

CC W/ enclosure: i R. Bernero J. P. Knight > -

R. Houston

0. Parr W. Butler G. Knighton H. Schierling J. Wermiel M. Ley J. Ridgely ,

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Contact:

J. Wermiel i X29462

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o DIABLO CANYON, UNITS 1 AND 2 RESPONSE TO ALLEGATION N0. 1545 AUXILIARY SYSTEMS BRANCH Task: Allegation or Concern No. 1545 Characterization Errors in the FLUD computer model used by the licensee to establish environ-ments in subcompartments following postulated high energy pipe breaks outside containment may result in incorrect pressure / temperature profiles for purposes of environmental qualification of safety-related equipment.

Implied Significance to Plant Design, Construction, or Operation Incorrectly defined pressure / temperature profiles for various subcompartments would mean that new analyses would be required using a different computer model. If the newly determined environments were significantly different from those previously defined, safety-related equipment would require j

requalification.

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Assessment of Safety Significance

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t The staff previousily reviewed and evaluated the licensees program (including use of the FLUD computer code) for establishing equipment qualification envelops as part of its review of the Diablo Canyon IDVP (refer to Diablo Can'or y SSER, NUREG-0675, Supplement No. 18). This evaluation included an independent calculation of the pressure / temperature profile for selected jubcompartmentsoutsidecontainmentutilizingtheCOBREEcomputercode. The siaff believes the COBREE model is the current state-of-the-art for analyses for this type and has been benchmarked against actual test results to confirm it's accuracy. The results of this comparison showed good correlation between

'the FLUD and COBREE calculated room pressures and temperatures.

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2 Staff Position Based on the above, the staff concludes that the licensee has utilized an acceptable methodology for determining subcompartment environments resulting from postulated pipe breaks outside containment. Therefore, the concerns expressed in this allegation do not impact our conclusion regarding the safety of the plant in this regard.

Action Required None

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