ML20214Q131

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Forwards Dissolved Hydrogen Concentration in Arkansas Nuclear One Unit 2 Pressurizer Repair Welds, Demonstrating Adequacy of Weld Repairs.Final Stress Calculation for X1 & T4 Heater Location Repairs Also Encl
ML20214Q131
Person / Time
Site: Arkansas Nuclear Entergy icon.png
Issue date: 05/21/1987
From: Tison Campbell
ARKANSAS POWER & LIGHT CO.
To: Murley T
NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM), Office of Nuclear Reactor Regulation
Shared Package
ML20214Q133 List:
References
2CAN058706, 2CAN58706, NUDOCS 8706040242
Download: ML20214Q131 (2)


Text

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ARKANSAS POWER & LIGHT COMPANY CAPIT0L TOWER BUILDING /P. O. 80X 551/LITTLE ROCK, ARKANSAS 72203/(501) 377 3525 T. GENE CAMPBELL May 21, 1987 Vice President Nuclear Operations 2CAN058706 U. S. Nuclear Regulatory Commission Document Control Desk Washington, DC 20555 ATTN: Mr. Thomas E. Murley, Director Office of Nuclear Reactor Regulation

SUBJECT:

Arkansas Nuclear One - Unit 2 Docket No. 50-368 l License No. NPF-6 ANO-2 Pressurizer Heater Repair -

Follow-Up Information t

Gentlemen:

As a follow-up to our letter of May 18, 1987 (2CAN058705) and discussions with your staff on May 19, 1987, pertaining to the weld repair of the ANO-2 pressurizer, attached is an analysis which demonstrates the adequacy of the weld repairs from a hydrogen embrittlement perspective. This analysis is consistent with work previously performed to address cladding failures at Yankee Rowe (WCAP-2855 " Evaluation of Yankee Reactor Vessel Clad Penetrations" submitted to the NRC in Yankee Atomic Elect.ric Company's letters of October 15, 1755 and WCAP-2859 " Yankee Pressurizer Clading Evaluation"). The ANO-2 analysis specifically addresses the unique characteristics of our repair which were of interest to the NRC staff.

These include sources of hydregen in the ANO-2 pressurizer for infusion into the weldment, diffusion calculations for the repaired areas, and acceptable steady state hydrogen concentrations which will ensure the welds' integrity.

Also attached is the final stress calculation for the X1 and T4 heater location repairs. These calculations were performed in accordance with the ASME codes and are based on final repair dimensions.

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8706040242 870521 PDR ADOCK 05000368 q p PDR I /

MEMBEA MiOOLE SOUTH UTILITits SYSTEM

May 21, 1987 Additional calculations have been performed to quantify the margin of safety which exists in the weld. These calculations, which are attached, show that considering the minimum weld depth specified for the XI penetration repair (actual weld depths are greater than those specified in the calculation) up to 96% of the weld circumference could fail without plug ejection. This same method showed that 93% of the T4 weld circumference could fail without risk of plug ejection.

Should the welds fail the ANO-2 Operators would be prepared to respond.

During the last cycle of requalification training (cycle 7, April 6,1987 through May 15,1987) ANO-2 operators had ANO-2 site specific simulator training on two different LOCAs. One LOCA ramped from 0 to 65 gpm in 15 minutes and maintained itself there for 30 minutes and then escalated to a complete double ended cold leg break. The second LOCA ramped from 0 to 500 gpm in 15 minutes and maintained this leak rate through the remaind u the transient.

The Cycle 8 requalification training (May 18, 1987 through June 26,1987) will include simulator training on a hot leg LOCA that ramps from 0 to 65 gpm in 15 minutes, maintains itself at this leak rate for 30 minutes and then ramps to 1000 gpm. These simulator training sessions afford the operators the best possible training on LOCA response.

Very truly yours, w w T. Gene Camp 11 TGC/DEJ/sg Attachments I

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