NSD-NRC-97-4958, Submits List of Dser Open Item Tracking Sys Items Considered Closed Re AP600 Reliability Assurance Program Completion

Submits List of Dser Open Item Tracking Sys Items Considered Closed Re AP600 Reliability Assurance Program Completion

ML20134Q017
Person / Time
Site:	05200003
Issue date:	02/07/1997
From:	Mcintyre B WESTINGHOUSE ELECTRIC COMPANY, DIV OF CBS CORP.
To:	Quay T NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NSD-NRC-97-4958, NUDOCS 9702260206
Download: ML20134Q017 (4)

Text

a e ,

e c =

Westinghouse Energy Systems Bm 355 Pmsburgh Pennsylvania 15230-0355 Electric Corporation .

NSD-NRC-97-4958 l DCP/NRC0715 Docket No.: STN-52-003 j February 7,1997  ;

Document Control Desk  !

U. S. Nuclear Regulatory Conunission Washington, DC 20555 ,

TO: T.R. QUAY

SUBJECT:

AP600 RELIABILITY ASSURANCE PROGRAM COMPLETION

REFERENCES:

1. AP600 SSAR REVISION 10 r

2. NSD-NRC-96-4830 (DCP/NRC0612), Markup Copy of the AP600 Reliability Assurance Program (RAP), SSAR Section 16.2, Dated 10/3/96

3. Letter from NRC to Westinghouse, fluffman to Liparuto Criteria for Establishing Risk Significant Structures, Systems, and Components (SSCs) to i be Considered for the AP600 Reliability Assurance Program, Dated 01/16/97.

4. Letter from Westinghause to NRC, DCP/NRC0583, Dated 8/20/96.

5. Letter from Westinghouse to NRC, DCP/NRC0484, Dated 04/01/%.

Dear Mr. Quay:

Reference i provided the AP600 Reliability Assurance Program (RAP), in Section 16.2 of SSAR ,

Revision 10. That RAP revision incorporated NRC review comments on the SSAR Revision 7 RAP, those received on the draft provided in Reference 2, and comments received during a telecon on 11/25/96.

As a result of completion of those activities, the Westinghouse status for the following DSER open item tracking system (OITS) items is Closed. Please provide an NRC status for these items so that i

. the OITS can be updated.

1286.

1288 1289 I

1291 1292 QDg63 ,S L g 12 % ij QU 1298 g 9702260206 970207 T PDR ADOCK 05200003i A PDR fg

$5%

l

• 3 1 NSD-NRC-97-4958 February 7,1997 j DCP/NRC0715 Also, attached is a RAP markup which reflects Expert Panel resolution of the items previously noted as "TBD" in RAP Table 16.2-1, specifically, the hydrogen ignitors and containment fan coolers. The hydrogen ignitors are now included in the RAP as explained in RAP Table 16.2-1. The containment fan coolers are not included in the RAP since the Expert Panel concluded that those components are not risk significant, based on the following.

As detailed in Reference 4, the AP600 design does not depend on active systems to remove airborne particulates from the containment atmosphere since naturally occurring passive aerosol removal processes provide significant removal capability. These processes include sedimentation, diffusiophoresis, and thermophoresis. These three aerosol removal processes are well established and have been confirmed in many separate-effects experiments, as discussed in accepted standards on aerosol mechanics. The large aerosol deposition contributions from diffusiophoresis and thermophoresis are due to the passive containment cooling system (PCS) providing a large heat transfer surface with a large heat transfer rate from the containment atmosphere to the containment wall. With the calculated removal coefficients and the core melt source term model from Reference 5, the AP600 passive design features provide for adequate removal of airborne activity since the airborne particulates are reduced to extremely low levels within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.

While the passive capability for reducing airborne activity concentration is slower than if active systems were credited, the passive removal processes are not subject to plausible equipment failures.

These processes are fail-safe and reliable, to an extent that would not be attained by active systems such as the AP600 nonsafety-related containment fan coolers. The fan coolers provide aerosol remov:d capability using the same processes of deposition as that occurring on the containment shell during PCS operation; however, no credit is taken for these fan coolers in the AP600 Accident Analyses.

1 Given the aerosol removal capability and reliability of the PCS and passive processes, the Expert  !

Panel has determined that the containment fan coolers do not meet the criteria for inclusion in the i Reliability Assurance Program, SSAR Section 16.2. l OITS item 3M3 was updated to show the Westinghouse action is now to include the attached RAP I markup in SSAR Revision 11. Upon review of this markup, please provide NRC status information to Westinghouse. With the attached markup, Westinghouse has completed all outstanding actions related to DSER Section 16.2 and follow-up meeting and telecons.

Westinghouse is still evaluating the impact of Reference 3 on the AP600 RAP; this is assigned item number 4852 in the OITS.

Please contact Robin K. Nydes (412) 374-4125 if you have any questions regarding this letter.

N A.

B. A. McIntyre, Manager Advanced Plant Safety and Licensing

/jml attachment

]

[

. e NSD-NRC-97-4958 February 7,1997 DCP/NRC0715 2

l cc: W. C. Huffman, NRC - (w/attacInnent) l J. Sebrosky, NRC - (w/ attachment) l N. Saltos, NRC - (w/ attachment) ,

F. Talbot, NRC - (w/ attachment) I T. Bergman, NRC - (w/ attachment)

N. Liparulo, Westinghouse - (w/o attachment) i i

i l~

l 3

i l.

( i i

.j l  :

I l

s 4

3 k

ATTACHMENT TO NSD-NRC-97-4958

. I6. Technical Specifications i

l I Table 16.2-1 (Sheet 12 of 13)

I l

RISK SIGNIFICANT SSCs UNDER THE SCOPE OF D-RAP l SSCm Rationale

• Insights and Assumptions l Component: Nonsafety-related diesels RTNSS These diesels provide ac power to I

support operation of nonsafety related l

equipment such as the startup l

feedwater system pumps, chemical l

and volume control system pumps, I

normal residual heat removal system I

pumps, component cooling water l

system pumps, service water system l

• pumps, and the plant control system.

l Providing ac power to the normal l

residual heat removal system and the I

eq'iipment necessary to support its I oper6 tion is RTNSS-important.

I System: Containment System Level 2. EP The containment provides a barrier I that separates the containment -

I atmosphere from the outside

! {, l environment following a breach of the J l RCS pressure boundary.  ;

I Component: Containment shell Level 2 + EP The containment shell provides a l barrier to steam and radioactivity I

released into the containment. The I I shell also provides heat transfer from l l the core to the atmosphere following l l accidents. 1 l Component: Passive containment cooling air- EP These valves open automatically to I operated drain valves drain water from a water storage tank I onto the outside surface of the l

containment shell. This water I provides evaporative cooling of the i l containment shell following accidents.

I Component: Hydrogen ignitors N '

- M __ _

l( Component: Containment fan coolers TBD / TBD

)

k 3 c, (c en nMS prtdck C\

(Dec05 40 CCdro\ ha @K.fibTMCn in we centcunmmt drmospeces

( censis4ed Mthre We%

%- en%\ retws menot~ g~hffo en

to cm se.M f. Revision

10 T Westingh0use 16.2-23 December 20,1996 l

1

,