ML20030C035
| ML20030C035 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 07/21/1981 |
| From: | Schuyler J PACIFIC GAS & ELECTRIC CO. |
| To: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| References | |
| IEB-81-03, IEB-81-3, NUDOCS 8108250335 | |
| Download: ML20030C035 (2) | |
Text
f DockhtNo. 50-275, 50-323/81-03 PACIFIC GAS AND ELECTR,IC C C M PANY b ' LsD 3
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77 BE ALE STREET
- SAN FR ANCISCO, C ALIFORNI A 94106
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Mr. R. H. Engelken, Director Offi of Inspection and Enformment
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U. S. Nuclear Regulatory Camlission
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Re: Docket No. 50-275 Diablo Canyon Units 1 and 2
- h N E [ [O Docket No. 50-323
Dear Mr. Engelken:
We have determined that Mytilus sp. larvae are found in the seawater at the Diablo Canyon site. Since Ccrbicula sp. are not found at the site, this addresses Mytilus sp. only.
PGandE operates several coastal power plants with potential probims similar to those outlined in IE Bulletin 81-03. Because of this, significant experience has been accumulated concerning mussel infestation and control. As a result, Diablo Canyon Power Plant has been designed to facilitate demusseling on a monthly basis using rejected candenser heat.
l The d musseling program kills mussels by heat treatment before the shells are too large to pass through the heat exchanger tubes of the cooling water systas. During this periodic deusseling, warmed salt-water is circulated througn these cmponents for a sufficient period of time to ensure mussel mortality. Similar demusseling programs have pro"en quite effective in preventing the buildup of mussel beds in cooling systems at other PGandE power plants. The extent of current infestation was evaluated on June 9, 1981 when the inlet water box of the ocmponent cooling water heat exchangers for Unit 1 was destered and inspected. No evidence of Mytilus sp. was discovered during that inspec-tion. The heat exchangers for Unit 2 were not inspected since they are not in service.
ff!I D108250335 810721
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PDR ADOCK 05000275 0
Mr. R. H. Enge1Aen July 21, 1981 The safety-related systms and emponents susceptible to fouling by Mytilus sp. are limited to the auxiliary saltwater systms (ASW) which rmove heat fran the cmponent cooling water systs. The primary cmpon-ents of this systs are the ASW pumps, ASW pipe, the cmponent cooling water heat exchanger and ASW valves.
In sumary, no corrective actions were necessary and the preven-tive actions, consisting of the monthly d m usseling program, are adequate to prevent future fouling by Mytilus sp. No further action is planned.
Approximately 25 man-hours were required to prepare this response.
Very truly y s,
J. O. SQiUYLER Subscribed and sworn to before me this 21st day of July, 1981 Theodora Cooke, Notary Public in and for the City and County of San Francisco, State of California My Camission expires January 28, 1935 Robert Ohlbach Philip A. Crane, Jr.
At s for Pacif
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4hO 11fp A Crane, J.
CC: Director Office of Inspection and Enforement U. S. Nuclear Pegulatory Cm mission Washington, D. C. 20555 l
l Director Docunent Managment Branch U. S. Regulatory Ccmnission l
Washingtcn, D. C. 20555 Service List l
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