ML20076E453
| ML20076E453 | |
| Person / Time | |
|---|---|
| Site: | Washington Public Power Supply System |
| Issue date: | 05/17/1983 |
| From: | De Lorenzo R WASHINGTON PUBLIC POWER SUPPLY SYSTEM |
| To: | Sternberg D NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| References | |
| 10CFR-050.55E, 10CFR-50.55E, GO1-83-0189, GO1-83-189, NUDOCS 8306010106 | |
| Download: ML20076E453 (2) | |
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Washington Public Power Supply System P.O. Box 968 3000 GeorgeWashington Way Richland, Washington 99352 (509)372-5000
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May 17, 1983 G
Docket Number 50-513 G01-83-0189 Nuclear Regulatory Commission Region V 1450 Maria Lane, Suite 210 Walnut Creek, California 94596 Attention:
Mr. D.M. Sternberg, Chief Reactor Projects Branch No. 1
Subject:
NUCLEAR PROJECT NO. 4 10CFR50.55(e) POTENTIALLY REPORTABLE CONDITION REACTOR VESSEL FLANGE STUD HOLE-STUCK STUD
Reference:
- 1) Telecon, C.R. Edwards, Supply System to A. D'Angelo, Region V. Nuclear Regulatory Commission, 11/15/82
- 2) G01-82-0805, dated December 14, 1982, R.W. Root to D.M. Sternberg In reference 1) the Supply System informed your office of a potentially reportable deficiency in accordance with the requirements of 10CFR50.55(e), and reference 2) was an interim report on the subject condition.
Attachment A of this report includes a statement of the corrective action taken to address the potentially reportable deficiency. Since it has been determined that the described deficiency does not require any rework or further action, the condition is considered not reportable; therefore this is a final report.
If you have any questions or desire further information, please advise, h
MW R.A. De Lorenzo, Program Director Attachment RAD /RL/cmh cc: JP Laspa, Bechtel (861)
V Mani, UE&C (897)
V Stello, Director of Inspection NRC A Toth, NRC (917Q)
ORM (847) l 8306010106 030517 i
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v-0 ATTACHENT A WNP-4 POTENTIALLY REPORTABLE CONDITION PER 10CFR50.55(e)
REACTOR VESSEL FLANGE STUD HOLE - STUCK STUD
Background
An alignment / handling stud used on the WNP-4 reactor vessel flange during handling operations was declared stuck when it became difficult to remove.
Subsequent destructive removal of the stud revealed dicontinuities of the thread form in the vessel flange and led to the issuance of Nonconformance Report 4-BNCR-04-03.
Description of Deficiency
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The deficiency can be described as the absence of several single thread forms of varying lengths.
The longest length of missing thread can be characterized as approximately one half of the stud hole circumference and the total length of missing threads is equivalent to approximately three circumferences.
Safety Implication The reactor vessel flange stud hole threads form a part of the mechanical interface for locking the reactor closure head to the reactor vessel.
Discrepancies in the stud hole thread form could have possibly affected the design requirements for maintaining the integrity of the primary reactor coolant pressure boundary.
When we first reported the problem in November, 1982, it was indeterminant as to whether the design requirements had been affected.
Corrective Action The deficiency was initially documented via the above mentioned BNCR, and a technical evaluation was subsequently performed by the vessel manu-facturer (B&W) and by the Engineer (United Engineers & Constructors).
This evaluation determined that the structural and functional integrity of the stud hole was acceptable and that no rework was necessary.
Since the dispositioned Noncomformance Report does not require any corrective or further action (use as is), the condition is not reportable and this will be our final report.