ML20138F117

Forwards RAI Re AP600 Containment Pressure Analysis in Section 6.2 of Ssar

ML20138F117
Person / Time
Site:	05200003
Issue date:	05/01/1997
From:	Huffman W NRC (Affiliation Not Assigned)
To:	Liparulo N WESTINGHOUSE ELECTRIC COMPANY, DIV OF CBS CORP.
References
NUDOCS 9705050265
Download: ML20138F117 (4)

Text

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~,N May 1, 1997 Mr. Nicholas J. Liparulo, Manager Nuclear Safety and Regulatory Analysis Nuclear and Advanced Technology Division Westinghouse Electric Corporation P.O. Box 355 Pittsburgh, PA 15230

SUBJECT:

AP600 CONTAINMENT PRESSURE ANALYSIS REQUESTS FOR ADDITIONAL INFORMA-TION (RAls)

Dear Mr. Liparulo:

In support of the AP600 design certification review, the Nuclear Regulatory Commission (NRC) staff is evaluatir.g containment pressurization analysis in Section 6.2 of the AP600 Standard Safety Analysis Report (SSAR). During a telephone conversation between Westinghouse and the NRC staff on April 23, 1997, the staff had discussions on containment subcompartment pressurization, external pressure analysis, and minimum backpressure analysis in which it was noted that information in the SSAR on containment pressurization is out-of-date and is in the process of being revised. To ensure that information the staff needs for its safety evaluation is documented, the staff has some RAls which are provided in an enclosure to this letter. .

If you have any questions regarding this matter, you can contact me at (301) 415-1141.

Sincerely, original signed by:

Will..m C. Huffman, Project Manager Standardization Project Directorate Division of Reactor Program Management Office of Nuclear Reactor Regulation Docket No.52-003

Enclosure:

As stated cc w/ enclosure:

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l ACRS (11) CBerlinger, 0-8 H7 MSnodderly, 0-8 H7 JDawson, 0-8 H7 cnM13 NRC FdTc CHfEB COPY DOCUMENT NAME: A:DWSN-CNT.RAI Ts aceive a copy of this document. inecate in the box: "C" = Copy without ettechment/ enclosure "E" = Copy with attachment /encloswa 'N" = No copy 0FFICE PM:PDST:DRPM D:PDST:DRPM NAME WCHuffman: 40 '

s TRQuay TOG DATE 05///97 05/1/97 "cICIAL RECORD COPY 9705050265 970501 PDR ADOCK 05200003 E PDR

~ N 1

Mr Nicholas J. Liparulo Docket No.52-003 1

Wes'inghouse Electric Corporation AP600 i

} cc: Mr. B. A. McIntyre Mr. Ronald Simard, Director

! Advanced Plant Safety & Licensing Advanced Reactor Programs Westinghouse Electric Corporation Nucleer Energy Institute

! Energy Systems Business Unit 1776 Eye Street, N.W.

P.O. Box 355 Suite 300 1

Pittsburgh, PA 15230 Washington, DC 20006-3706

Ms. Cindy L. Haag Ms. Lynn Connor

! Advaticed Plant Safety &. Licensing Doc-Search Associates 5

Westinghouse Electric Corporation Post Office Box 34 4 Energy Systems Business Unit Cabin John, MD 20818 Box 355

Pittsburgh, PA 15230 Mr. James E. Quinn, Projects Manager LMR and SBWR Programs

Mr. M. D. Beaumont GE Nuclear Energy

Nuclear and. Advanced Technology Division 175 Curtner Avenue, M/C 165 i Westinghouse Electric Corporation , San Jose, CA 95125 1 One Montrose Metro i 11921 Rockville Pike Mr. Robert H. Buchholz L Suite 350 .GE Nuclear Energy j Rockville, MD 20852 175 Curtner Avenue, MC-781 San Jose, CA 95125

Mr. Sterling Franks i U.S. Department of Energy Barton Z. Cowan, Esq.

! NE-50 Eckert Seamans Cherin & Mellott

! 19901 Germantow'n Road 600 Grant Street 42nd Floor j Germantown, MD 20874 Pittsburgh, PA 15219 l Mr. S. M. Modro Mr. Ed Rodwell, Manager l Nuclear Systems Analysis Technologies PWR Design Certification f

Lockheed Idaho Technologies Company Electric Power Research Institute

! Post Office Box 1625 3412 Hillview Avenue

Idaho Falls, ID 83415 Palo Alto, CA 94303

l. Mr. Frank A. Ross Mr. Charles Thompson, Nuclear Engineer i U.S. Department of Energy, NE-42 AP600 Certification

Office of LWR Safety and Technology NE-50 19901 Germantown Road 19901 Germantown Road l Germantown, MD 20874 Germantown, MD 20874 1

e i .

i

- N AP600 SSAR SECTION 6.2 REQUESTS FOR ADDITIONAL INFORMATION I. Containment Subcompartment Pressurization Analysis 480.1037 What is the basis for the 5 psid differential pressure for the sub-compartment walls? Is this based on some design value, or does it simply represent a value that bound the loads produced by the most limiting break in the subcompartment?

480.1038 SSAR Figure 6.2.1.2-1 shows a blowout seal. It is the staff's under-standing from SSAR Rev. 5 that Section 6.2.1.2 that no credit is taken for vent paths that become available only after occurrence of a postulated break.

(a) Does the presence of the seal contradict this statement?

(b) What analysis has been done to confirm that this seal will blowout when necessary? Provide details.

480.1039 Provide justification that the pipe breaks assumed for the reactor vessel i cavity asymmetrical loading analysis and IRWST analysis are bounding for '

these compartments. l 1

480.1040 What is the limiting pipe break for the CVS compartment and design differential pressure for the CVS compartment?

II. Containment External Pressure Analysis i

480.1041 The event used for the containment external pressure analysis (loss of '

all AC) is beyond design basis.

(a) What is the justification for considering a beyond design basis event instead of a design basis event for the maximum external pressure analysis?

(b) How would the consequences of a DBA event compare with those of a beyond-design basis event.

480.1042 Section 6.2.1.1.4 of SSAR, Rev. 5, states that "For the loss of all AC power, service level C limits are applicable and a containment external pressure of 3.0 psid is permitted." For a buckling analysis, the staff's understanding is that ASME service level limits are not applicable. This correction / clarification should be made in the latest SSAR revision, and l the basis for the design differential pressure limit should be clarified. '

480.1043 Provide the staff with justification that the scenario described in the SSAR is the bounding event for containment external pressure loads.

Discuss what other events were considered and how it was determined that these were not bounding. In particular, discuss if an inadvertent l actuation of the PCCS was considered, and why this occurrence is not '

bounding.

Enclosure l

A.

P III. Containment Minimum Backoressur6 Analysis 480.1044 What is the objective / basis of the minimum backpressure analysis, given that the AP600 has no safety-related pumps. That is, in what analyses is the minimum containment pressure bounding? How does this relate to containment conditions during long term recirculation cooling or the core.

480.1045 For the containment minimum backpressure analysis, how was the PCCS flow modeled (full flow, partial flow, etc.)? Provide justification for the PCCS modeling used.

480.1046 Specify what values of initial containment pressure, temperature, and relative humidity were used for containment minimum backpressure analy-sis. Are these minimum or maximum values?

IV. Editorial Comment SSAR Section 6.2.1.5 refers to a containment backpressure figure (Fig-ure 6.2.1.5-1). This figure does not appear to be provided in the SSAR.