ML20078S036

Forwards Sbwr Drywell to Wetwell Vacuum Breaker Valve White Paper, in Response to Item 42 in Attachment 2 to GE ,Presenting Addl Info Re Exemption of Sbwr Vacuum Breakers from Single Failure Criteria

ML20078S036
Person / Time
Site:	05200004
Issue date:	02/16/1995
From:	Quinn J GENERAL ELECTRIC CO.
To:	Borchardt R NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM), Office of Nuclear Reactor Regulation
Shared Package
ML20078S040	List: ML20078S036 ML20078S044
References
MFN-021-95, MFN-21-95, NUDOCS 9502230274
Download: ML20078S036 (2)

Text

,

GENuclearEnergy MRnY'8 k165 San Jose, CA 95125-1014 75 Cu n

406 925-1005 (phone) 406 925-3991 (facsimile)

February 16,1995 MFN No. 021-95 Docket STN 52-004 Document Control Desk U. S. Nuclear Re latory Commission Washington DC p0555 Attention:

Richard W. Borchardt, Director Standardization Project Directorate

Subject:

Request for Exemption of the SBWR Drywell to Wetwell Vacuum Breaker from the Single Failure Criteria

Reference:

1. GE letter AfFNNo. 018-95,J. E. Quinn (GE) to R. W. Borchardt (NRC), " Approach to Achieve Closure ofItems Related to the GE SBWR TAPD, " dated 1%ntary 14,1995.

2. Letter, T. R. hicIntyre (GE) to Richard W. Borthardt (NRC),

Responses to the Referenced Istters, GE AffN No.113-94, dated September 26,1994.

3. Letter, J. E. Leathennan (GE) to Richard W. Borchardt (NRC),

NRC firquestsfor AdditionalInformation (RAIs) on the Simpitfied Boiling Water Reactor (SBWR) Design, GE AffNNo. 065-94, dated Afay 2,1994.

The "SBWR Dnwell to Wetwell Vacuum Breaker Valve White Paper" Attachment to this letter is the GE response to item No. 42 in Attachment 2 to the Reference I letter. The purpose of this paper is to present additional information regarding exemption of the SBWR vacuum breakers from the single failure criteria based on demonstrated reliability.

The paper describes the design features of this special vacuum breaker valve which significantly improve its leak tightness and reliability perfonnance. The paper also presents the rigorous leak tightness, perfonnance, Design Basis Accident (DBA), and reliability testing which the valve has successfully undergone in substantiating this exemption from the single failure criteria.

In the GE Response to RAI Number 900.63 (Reference 2), a discussion of vacuum breaker actions for analyses, transients and accidents, including a Gravity Driven Cooling System (GDCS) line break and discussion of assumptions made for both 9502230274 950216 PDR ADDCK 05200004 PDR Y'

e GENuclearEnergy MFN No. 021-95 Page 2 l

l expected and " licensing basis" scenarios was presented. Reference 2 also included detail l

as to why failure to close (after actuation) of a dowell to wetwell vacuum breaker is not, in GE's view, a credible failure.

In the GE Response to RAI Number 900.62 (Reference 3), information was presented to j

enable the staff to access the adequacy of the wetwell-to-dowell vacuum breaker test i

program including: drawings of the vacuum breaker and instrumentation; the vacuum breaker Purchase Specifications; a copy of the Engineering Operating Procedure; detailed specification of the conditions, both normal and design basis, under which the vacuum breakers will be required to operate; the detailed test procedures for the vacuum breaker; and mformation appropriate to ensuring that the data obtained on the reliable performance of the valve is applicable to the valves to be incorporated into the certified j

plant design.

We hereby request your review of this letter along with the references and approval of this request for exemption of the subject vacuum breaker from having to meet the single failure criteria for application to the SBWR.

Sincerely,

/

f~

Jame

. 'uinn, Projects Manager

'13 and SBWR Programs

Enclosure:

SBWR Dowell to Wetwell Vacuum Breaker Valve White Paper cc:

P. A. Boehnert (NRC/ACRS)

I. Catton (ACRS)

S. Q. Ninh (NRC)

J. IL Wilson (NRC)

...<