ML20044G985
| ML20044G985 | |
| Person / Time | |
|---|---|
| Site: | 05200001 |
| Issue date: | 05/26/1993 |
| From: | Crutchfield D Office of Nuclear Reactor Regulation |
| To: | Marriott P GENERAL ELECTRIC CO. |
| References | |
| NUDOCS 9306070141 | |
| Download: ML20044G985 (3) | |
Text
'
g[paro 3b, UNITED STATES v
f' S
NUCLEAR REGULATORY COMMISSION 1
E h
WASHINGTON, D.C. 20555-0001 k
p' May 26, 1993 j
Docket No.52-001 1
Mr. Patrick W. Marriott, Manager Licensing & Consulting Services GE Nuclear Energy 175 Curtner Avenue San Jose, California 95125'
Dear Mr. Marriott:
i
SUBJECT:
ADVANCED BOILING WATER REACTOR (ABWR) DESIGN BASIS LOADING COMBI-NATIONS In the ABWR standard safety analysis report (SSAR), one of the American Society of Mechanical Engineers (ASME) Service Level D (faulted) loading combinations consists of normal operating loads + loss-of-coolant-accident -
(LOCA) + safe-shutdown earthquake (SSE). This design basis loading combi-nation is consistent with the staff's position in the standard review plan 3.9.3.
In a letter dated March 5,1993, General Electric (GE) requested a deviation from this position by proposing that, for piping design only, the dynamic loads associated with annulus pressurization (AP) be decoupled from the SSE. The AP loads are one of the large break LOCA loads resulting from a rupture of either the main steam (MS), feedwater:(FW), or residual heat removal (RHR) lines in the annulus between the reactor pressure vessel (RPV) 4 and the shield wall.
There are twelve specific breaks that could cause AP loads, i.e., 4 MS, 6 FW, and 2 RHR (system). GE's basis:for this request consists of an estimate that the probability of an SSE event causing pipe break at a specific high stress joint, such as a pipe to RPV nozzle connec-J tion, is approximately 2x10" per reactor year.
GE further states that designing this pipe to the AP + SSE loads results in' a. greater number and larger size of supports in the piping system that do not contribute to the overall safety and reliability of that system.
The staff agrees that the probability of the simultaneous occurrence of these two loads is extremely small. However, the staff has not yet endorsed the use i
of a probabilistic approach as a basis for decoupling the SSE and LOCA loading combination. The staff's position on combining SSE and LOCA loads does not assume that the SSE load initiates a LOCA in a' seismic Category I pipe.
i
,N y, Q, % V'M%f Meq 010.005 I g, 9306070141 930526 n
0 PDR ADOCK 0520 1
y
l b
t Patrick W. Marriott May 26, 1993 j
Rather, these loads are considered as two independent events. _The.'staf.f has traditionally implemented this conservative position to' satisfy GDC 2 in 10 CFR Part 50, Appendix A and to provide sufficient margin in the design of applicable items to account for unanticipated loads _ and/or degradation. _ These margins have served as.one important element in the implementation of the i
defense-in-depth-regulatory philosophy'by often providing key bases for the
?
staff to justify and allow continued operation of. existing plant systems, components or structures whenever load demands for such-items had to be increased for a variety of reasons (e.g., increased hazards,. design errors, or modifications). This position is consistent with that stated in Vol:. 2,
- Part 1, Section 4.6.2 of.NUREG-1242, "NRC Review of EPRI's ALWR Utility.
Requirements Document." Therefore, the staff does not accept the GE-request i
to decouple AP +-SSE loads.
I l
. Notwithstanding the staff position stated above, an alternative for GE is to i
apply the " leak-before-break" (LBB) method to eliminate the need to design for the dynamic effects of postulated pipe breaks; in which the combination. of SSE.
and LOCA loads effectively reduces to the SSE load alone..In the.ABWR SSAR, j
Section 3.6.5.2, the COL applicant has an option to submit the LBB analysis 1
for staff review. We suggest that the LBB analysis for this 'particular area be included as part of the COL application.-
j 1
Please provide a response to this letter regarding your position on the decoupling request.
Sincerely, Odgia 9tgngg.
y
-Dennis M. Crutchfield, Associate Director for Advanced Reactors and Licence Renewal Office of Nuclear Reactor Regulation cc: See next page DISTRIBUTION:
. Docket File
.PDST R/F DCrutchfield RBorchardt PDR JNWilson CPoslusny
.SNinh DTerao, 7H15 HBrammer, 7H15 GBagchi, 7H15 ACRS (11)
GGrant, ED0 JMoore, 15B18 PShea LShao, RES BHardin, RES J0'Brien, RES A
0FC:
LA:PDST:ADAR.
PM:PDSf:ADARM )ADAR NSDST:ADAR AQARtNRR A v
v v
cm y w NAME:
PShea ey4rv CPoslusny:sg JNWilson RBorchardt DCYutchfield DATE:
05/26d3 05/')(./93 05/U/93 05/N93 05/74/93 0FFICIAL RECORD COPY:
DOCUMENT NAME: ABWRLTR.CP
.i 1
Mr. Patrick W. Marriott Docket'No. S2-001 General Electric Company cc:
Mr.' Robert Mitchell.'
Mr. Joseph Quirk General Electric Company GE Nuclear Energy 175 Curtner Avenue.
General Electric Company San Jose, California 95125 175 Curtner' Avenue, Mail Code 782:
San Jose, California 95125 Mr. L.'Gifford, Program Manager Regulatory Programs GE Nuclear Energy 12300 Twinbrook Parkway Suite 315 Rockville, Maryland. 20852 Director, Criteria & Standards Division Office of Radiation Programs U..S. Environmental Protection Agency 401 M Street, S.W.-
Washington, D.C.
20460 Mr. Sterling Franks U. S. Department of Energy NE-42 Washington, D.C.
20585 Marcus A. Rowden, Esq.
Fried, Frank, Harris, Shriver & Jacobson 1001 Pennsylvania Avenue, N.W.
l Suite 800 Washington, D.C.
20004 Jay M. Gutierrez, Esq.
j Newman & Holtzinger, P.C.
1615 L Street, N.W.
Suite 1000 Washington, D.C.
20036 4
.-,..