ML17054C235

License Amendment Request for the Transition to Westinghouse Core Design and Safety Analyses - WOG-93-066

ML17054C235
Person / Time
Site:	Wolf Creek
Issue date:	01/17/2017
From:	Wolf Creek
To:	Office of Nuclear Reactor Regulation
Shared Package
ML17054C103	List: ET 17-0001, License Amendment Request for the Transition to Westinghouse Core Design and Safety Analyses, Enclosure 10 - CAW-16-4500 ML17053B393 ML17054C219 ML17054C220 ML17054C221 ML17054C222 ML17054C223 ML17054C224 ML17054C226 ML17054C227 ML17054C229 ML17054C230 ML17054C232 ML17054C233 ML17054C235 ML17054C236
References
ET 17-0001
Download: ML17054C235 (2)

Text

r UNirf.D STATU Attachment to WOG-93-066 NUCLEAR REGULATORY COMMISSION WASHINOTO ... 0 C. %0551 March 10, 1993 Mr. Lawrence A. Walsh, Chairman Westinghouse Owners croup North Atlantic Energy Services corporation P. 0. Sox JOO seabrook, NH OJ874

Dear Mr. Walsh:

SUBJECT : Westinghouse owners Croup-Steam Generator Tube

~ Uncovery Issue

References:

(l) WCAP-13247, "Report on the methodoloqy tor th@ resolution of the steam qenerator tube uncovery iasu*." dated March 1992.

(2) letter !rom Lawrence A. Walsh to Robert c.

Jones, "Westinghousa Owners croup - Steam generator tube uncovery issue," dated March 31, l9SJ2.

(J) Memorandum from LeMoine J . cunningham to Robert C. Jcnes, "WCAP-1J247," report on the methodoloqy !or the resolution ot the steam generator tube uncovery issue," submitted by Westinghouse Owners Croup dated Septemb~r 14, 1992.

In July 1987, North Anna Unit 1 steam generator tube rupture 1ndicated that the apex of the steam generator tubes may have been partially uncovered for 10-15 minutes. In response to concerns expressed by the NRC staff, the Westinghouse owners Group (WOG) initiated & program in ~9e8 to de~ermine if the iodine release resulting from partial uncovery of ste~~ qenerator tubes during a steam generator tube rupture (SCTR) event or other limiting event can have a s1gnificant safety impact on Westinghouse plants. As discussed in your letter of March 31, 1992 (Ref. 2), we understand that th~ WOG has completed its work on this matter, and that WCAP-13247 (Ref. 1) demonstrates that a significant safety issue does not ~xist for Westinghouse facilities.

Based on our review of WCAP-13247, it is our understanding that Westinghouse performed representative SGTR analyses using the LOFTTR2 computer code to characterize the thermal and hydraulic response to various SGTR scenarios for representative plants and L

to provide boundary conditions tor the mixture level model. The represQntative plants used !or the analyses were a !our-loop plant with model ~l steam generators and a two-loop plant with model 44 tteam generators. These plants were selected beca~**

model 51 and model 44 steam generators a~e expected to be most susceptible to tube uncovery during an event. Westinghouse pertormed the LOFTTR2 analyaes tor the following accident scenarios: (a) SGTR with a stuck-open PORV; (b) SGTR with a modulating PORV; and (c) SGTR with a cycling safety valve. The stuck-open PORV case resulted in the highest steam release and consequently the greatest of!site dose consequences. The results ot these LOFTTR2 ar.alyses were then used as boundary conditions to com~ute the st~am gen*ratvr watec level tor the duration of these events. The results o! ~he iodine release calculation indicated th~t the SGTR analysis with a stuck-open PORV yields the highest iodine release with only about 1\ ot the release being attributable to steam generator tube uncovery. Thus,

) Westinghouse concluded that the ettect o! tube uncovery is esaentially negligible tor the limi~inq transient, and that the curr~nt design basis SGTR analysis methodology remains valid.

Based on our review ot your submittal, we believe that the WOG program repre3ents a comprehensive e!tort to address the staff's concerns. The assumptions and parameters used in the iodine transport quanti!icati~n are consistent with the criteria established by the staff in the Standard Review Plan (Section

. )

15.6.3), and the Westinqhouae a~alysea demonstrate that the e!!ects of partial steam ~enerator tube uncovery on the iodine release !or SGTR and non-SGTR events is negligible. Therefore, we agree ~ith your position on this ~atter and consider this issue to be resolved.

Thank-you tor your attention and efforts in resolving this matter.

Sincerely, C.tcfl4f.t Reactor Systems Branch Division of Systems Safety and Analysis cc: .t~; voyt:ell:.~q\0, A. Engel (TU Electric)

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