ML20206A193

Provides Response to Generic Ltr 88-11, Radiation Embrittlement of Reactor Vessel Matls. Based on Analysis of Reg Guide 1.99,Rev 2 to Draft Rev 2,reanalysis of RCS Heatup & Cooldown & Mitigation Sys Setpoints Unnecessary

ML20206A193
Person / Time
Site:	Wolf Creek
Issue date:	11/07/1988
From:	Withers B WOLF CREEK NUCLEAR OPERATING CORP.
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
RTR-REGGD-01.099, RTR-REGGD-1.099 GL-88-11, WM-88-0290, WM-88-290, NUDOCS 8811150001
Download: ML20206A193 (3)

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WQLF CREEK NUCLEAR OPERATING CORPORATION Bart D. Withers gg. November 7,1988 WM 88-0290 U. S. Nuclear Regulatory Commission ,

ATTN Document Control Desk Mail Station Pl-137 '

Washington, D. C. 20555 References ET 88-0084, dated June 20, 1988 from J. A. Bailey to NRC

Subject:

Docket No. 50-482: Ceneric Letter 88-!! - Radiation Embrittlement of Reactor Vessel Materials (

Centlement The purpose of this letter is to provide Wolf Creek Nuclear Operating Corporation's ( WCNOC) response to the Generic Letter 88-11. Generic  !

Letter 88-11 states that licensees of operating reactors should use the me t hod s described in Revision 2 to Regulatory Guide (R.C.) 1.99 to predict the effect of neutron radiation on reactor vessel materials. It also requests that licensees submit to the NRC within 180 days of the ef fective  !

date of Revision 2 the results of their technical analysis to the R.G. 1.99 Revision 2 criteria and a proposed schedule for whatever actions they plan to take.

In early 1988, WCNOC performed an analysis of the first reactor vessel  ;

material sample, which was removed f rom the Wolf Creek Cenerating Station  ;

(WCCS) reactor vessel during the VCCS first refueling outage. This anlaysis was pe r f o rmed using the methods described in "Draft Revision 2" to [

Regulatory Cuide 1.99 and was utill ed to revise the WCCS Cold Overpressure i Mitigation Systems (COMS) setpoints, Reactor Coolant System heatup and l cooldown rates and associated Technical Specifications. As a result of this ,

analysis revisions to the WCCS Technical Specifications were submitted by  !

the Referenced letter.

An analysis of the differences between "Draft Revision 2" and Revision 2 as issued has been pe r formed. The methodology, as delineated in R.C. 1.99 Revision 2, requires the calculation of the attenuation in the neutron I fluence due to reactor pressure vessel wall self-shielding before l calculating the change in ART # '"Y #" " " **"" * **

wall. The "Draft Revision 2"NDTmethod required calculating the ARTNDT "  !

wetted surface first and then adjusting it for location sensitive reactor pressure vessel wall self-shielding effects. The R.C. l.99 "Draft Revision 2" approach to calculatigg the predicted ORT for Wolf Creek .

yields marginally higher (1 to 3 T shif t) predicted Ab7HDT ** *' #" ""  !

requires a more restrictive pressure-temperature window for low temperature r operations and Low Temperature Overpressure Protection Setpoints. [

5911150001 8 E 11 F { i FM AD0i> 050 iO4 K r P0t~ i' PO. Son ati / Syrfrgton, AS 66839 / Phone:(316) 36a-6831 j eIw CWwv*yt w M*ctT l 6

VM 88-0290 Page 2 of 2 November 7 , 1968 The revised Reactor Coolant System heatup, cooldown, COMS setpoint limit curves and COMS setpoints valid up to 7 Ef fective Full Power Years (EFPY) for WCCS (submitted by the Re f e re nc e) obtained using the "Dra f t Revision 2" procedures are more conservative than the curves that would have resulted from the use of R.C. 1.99 Revision 2.

Based on our analjsis of R.C. 1.99 Revision 2 as c ompare d to "Draft Revision 2", it has been concluded that a re-analysis of the Reactor Coolant System heatup, cooldown, COMS Setpoint limit curve and the COMS setpoints is not necessary. The limit curves based on "Dr$f t Revision 2" are more conservative than those that would be obtained if the final version of R.C. l.99 Revision 2 were used. Future analyses completed as required by 10 CFR 50 Appendix C will be performed utilizing Revision 2 of R.G. l .99.

If you have any questions concerning this matter, please contact me or Mr. O. L. Maynard of my staf f.

Very truly yours,

- J Bart D. Withers President and Chief Executive Officer BDW/jad cct B. L. Bartlett (NRC)

D. D. Chamberlain (NRC)

R. D. Mart in ( NRC)

D. V. Pickett ( N RC)

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, ,o STATE OF KANSAS ) ,

) SS -

COUNTY OP COPPRY )

Bart D. Withers, of lawful age, being first duly sworn upon oath says that he is President and Chief Executive Officer of Wolf Creek Nuclear Operating '

Corporations that he has read the foregoing document ar.1 knows the content thereof that he has executed that same for and on behalf of said Corporation with full power and authority to do so and that the facts therein stated are true and correct to the best of his knowledge,  !

information and belief. j

. I 37 b I Bart D. Withers '

President and Chief Executive Officer i w

SUBSCRIBED and sworn to before me this 7 day of2 W ol*T 1988.

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