ML20011D684
| ML20011D684 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 12/14/1989 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20011D683 | List: |
| References | |
| NUDOCS 8912280250 | |
| Download: ML20011D684 (1) | |
Text
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UNITED STATES g
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p, NUCLE AR REGULATORY COMMISSION l
E W ASHINGTON, D. C. 20555 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATING TO 16500 INSPECTIONS AND REPAIRS MILLSTONE NUCLEAR POWER STATION, UNIT 1 NORTHEAST NUCLEAR ENERGY COMPANY DOCKET NO. 50-245
1.0 INTRODUCTION
During the 1989 Millstone Unit I refueling outage,150 austenitic stainless steel welds (99 in the drywell and 51 in the reactor building) subject to-intergranular stress corrosion cracking (IGSCC)'were scheduled to be ultra-sonically inspected. The results of the inspection showed that of the 155 welds
~ actually examined, one weld, CUAJ-5, an 8" IGSCC Category "D" weld located in the reactor water cleanup system, was found to contain a flaw indication. -The dead!e N th" weId N a ba die!gWand !0 kn epth.
The weld was repaired using a full structural weld overlay reinforcement. The-five " extra" welds examined included four additional Category "D" welds added to expand the sample size because of the flaw indication in weld CUAJ-5 and a weld next to a weld found to be flawed in the 1987 IGSCC inspection.
j 2.0 DISCUSSION The staff has reviewed the licensee's July 27, 1988, response to the requirements of Gentric Letter 88-01, "NRC Position on IGSCC in BWR Austenitic Stainless Steel Piping", the IGSCC inspection plans for the 1989 refueling outage dated February 3,1989, and the IGSCC inspection results dated May 4-and May 17, 1989.
3 The staff reviewed the weld overlay design details presented in the May 17, 1989, 4
submittal ard by letter dated May 22, 1989, the staff made a finding that it was acceptable for Millstone Unit 1 to restart from the refueling outage and operate in its present configuration throughout Cycle 13.
An NRC inspector witnessed and verified the IGSCC inspections during May 1-5, 1989. The results of the inspection are presented in Inspection No. 50-245/
89-11, dated June 9, 1989. The inspection concluded that the licensee's IGSCC activities complied with the applicable requirements.
3.0 CONCLUSION
Based on our review of the licensee's submittals and on the results of an NRC inspection, we conclude that the 1989 refueling outage IGSCC inspection plan, results and repair are acceptable such that Millstone 1 can be safely operated in its present configuration through Cycle 13 (currently scheduled to continue until Winter 1990-1991.
Date:
December 14, 1989 Principal Contributor:
M. Boyle
'8912280250 891214 PDR ADOCK 05000245 g
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