ML20003B649
| ML20003B649 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 02/17/1981 |
| From: | Mroczka E NORTHEAST NUCLEAR ENERGY CO. |
| To: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| References | |
| MP-2-4599, RO-50-336-81-8, NUDOCS 8102250092 | |
| Download: ML20003B649 (1) | |
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- --February 17, 1981 MP-2-4599
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Mr. Boyce H. Grier Director l Region I 3
Office of Inspection and Enforcement 5
U.S. Nuclear Regulatory Comission 631 Park Avenue
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Reference:
Facility Operating License No. DPR-65 Docket No. 50-336 Reportable Occurrence 50-336/81-8 j
Dear Mr. Grier:
j This letter provides notification of Reportable Occurrence 81-8 pursuant to the requirements of Millstone Unit 2 Appendix A Technical Specifications, Section 6.9.1.8.i.
The report concerns the discovery of conditions that require corrective measures or remedial action to prevent the existence or development of an unsafe condition.
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As a result of an as-built hanger review of the Reactor Vessel Head Vent Piping System, it was determined that a spring can type hanger was installed incorrectly.
This system was modified extensively during the past refueling outage to install remotely operated head vent valves.
The hanger was located on 1"-ECD-5 (governing code ANSI B31.1), but the improper installation resulted in overstressing a socket welded joint of a 3/4" x l' tee in 1"-CCA-18 (governing code ASME Section III, Class 1).
Failure at the joint would have resulted in a non-isolable Reactor Coolant System leak. The stresses wert. reduced to less than allewable by recoving the spring can hanger and isolating then depressurizing the tee.
Repairs and/or modifications to the Head Vent System are being evaluated and will be completed during a fetr>re autage of sufficient length.
In the interim, the head vent piping and specifically the overstressed joint will remain isolated and de;iressurized, o01
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0102250092 5
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Any further information will be provided in the two week report.
You n truly, j
NORTHEAST NUCLEAR ENERGY COMPANY h
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. Mroczka h'
Station Superintendent 1
Millstone Nuclear Power Station
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