ML19345G116
| ML19345G116 | |
| Person / Time | |
|---|---|
| Site: | Humboldt Bay |
| Issue date: | 11/20/1974 |
| From: | PACIFIC GAS & ELECTRIC CO. |
| To: | NRC COMMISSION (OCM) |
| References | |
| RO-135, NUDOCS 8103020486 | |
| Download: ML19345G116 (2) | |
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- l No.
135 Date: 11/20/74 DIRECTORATE OF REGULATORY OPERATIONS NOTIFICATION OF AN INCIDENT OR OCCURRENCE
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Facility:
PACIFIC GAS AND ELECTRIC COMPANY (HUMBOLDT BAY UNIT 3)
Problem:
FAILURE OF "U" BOLTS HOLDING FEEDWATER SPARGER
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INSIDE REACTOR VESSEL The licensee-reported to Region V by telephone on November 18, 1974, that an inspection of the feedwater sparger inside the-reactor vessel on November 17, 1974, during a routine refueling outage disclosed that five of eight, one-half inch, 304 stainless steel "U" bolts holding the sparger in place on support brael ets had failed (three on both sides of the "U" bolts and two on on side only). The remaining three "U" bolts were bent. The sparger ha moved approximately two inches laterally away from the inlet line side of the vessel. The sparger-is slipfit inside a fairly lcng thermal sleeve and would not, according to the licensee, have come out of the sleeve even had it moved against the vessel wall. Therefore, there was no loss of the normal and/or safety function of the system. Additional information received from the licensee was as follows:
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- 1. The cause of the "U" bolt failures is under investigation by PG&E and the General Electric Company, and will be determined during the current refueling outage. Repairs to the sparger supports a,re not expected to substantially increase the length of the outage. However, radiation levels could affect the time of repair.
- 2. There was no loss of the "U" bolt pieces, since its were captured by tack welding in place at the time of construction and the top portions of the "U" bolts were still in place on top of the sparger ring.
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- 3. The licensee will submit a 10-day written report of the occurrence.
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Action by Regulatory Operations:
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- 1. Region V inspectors will maintain contact with the licensee f
regarding its investigation of the mechanism of failure.
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- 2. A site visit by Region V has been scheduled for December 2, 19es.
prior to anticipated plant startup in mid-December.
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- 3. A local press release was made by Region V.
- 4. The assistants to the Commissioners, the staff of the Joint Committee on Atomic Energy and the Office of Information 7
Services have been notified by telephone.
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No.
135 2-Date: 11/20/74 contact:
Further infomation concerning this occurrence au be obtained from:
J. L. Crews
- X7353 H. D. Thornburg-X7353 8g, j 33 J. G. Davis
- X7541 Distribution:
Chairman Ray E. G. Case, L Commissioner Kriegsman F. Schroeder, L Commissioner Anders D. J. Skovholt, L L. M. Muntzing, DR A. Giambusso, L A. W. Jackson, ATDR H. Larson, L L. V. Gossick, ADR K. R. Goller, L
- h. H. Brown, DRGL S. A. Schwartz, DRGL S. H. Hanauer, DRTA H. C. Kouts, RSR E. G. Triner, DRPA R. S. Boyd, L D, J. Donoghue, DRA A. R. Rosenthal, ASLAP W. G. Dooly, DRA S. H. Smiley, L teneral Manager (2)
D. R. Muller, L Secretary (2)
R. L. Tedesco, L F. Ingram, IS H. R. Denton, L (2)
J. Fouchard, IS D. A. Nussbaumer, L J. A. Harris, IS R. E. Cunningham, L Clare Miles, IS G. W. Kerr, L J. D. Anderson, INS B. Singer, L M. Biles, OS L. I. Cobb, RO R. F. Fraley, ACRS (18)
D. F. Kruth, RO
- l L. Rogers, RS J. G. Tavis, RO R. Mattson, RS H. D. thornburg, RO J. A. Arlotto, RS T. R. wilson, RO J. J. Davis, RS D. Thompson, R0(2)
R. G. Smith, RS B. H. Grier, R0 (2)
R. S. Brodsky, NR G. W. Reinmuth, RO W. MacDonald, OPS K. V. Seyfrit, RO (4)
J. L. Liverman, DBER J. Sniezek, R0 (4)
S. Levine, OEA C. W. Kuhlman, RO DR Central Files J. Whiteaker, RO (4)
RO Files R. D. O'Neill, OCR PDR (4)
W. H. Weysen, DBER E. J. Bauser, JCAE A0 egional Offices B. F. Faulkenberry, RO Reading Files
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F. D. Anderson, L l
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