ML19210B439
| ML19210B439 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 09/10/1973 |
| From: | John Miller Metropolitan Edison Co |
| To: | O'Reilly J NRC Office of Inspection & Enforcement (IE Region II) |
| References | |
| NUDOCS 7911080661 | |
| Download: ML19210B439 (2) | |
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- cette /3e r* M sJJ METROPOLITAN EDISON COMPANY PC3T OFFICE COX L.:2 REACING. PENNsYLVANI A 19003 TELEPHONE 215 - 9 0 2001 September 10, 1973
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1 WAJ Mr. James P. O'Reilly, Director Directorate of Regulatory Operations Regic,n i United States Atomic Energy Coccission 631 Park Avenue King of Prussia, Pa.
19406
SUBJECT:
THREE MILE ISLAND NUCLEAR STATION UNITS 1 & 2 DOCKET NO. 50-289 AND 50-320
Dear Mr. O'Reilly:
This letter is in response to the Coc=1ssion's letter of July 18, 1973 which requested that we review the design of the control circuits for the Containment Ventilation System isolation valves in-stalled at Three Mile Island Nuclear Station Units No. 1 and 2.
This review has determined that no single failure of one containe nt isola-tion valve nor its control circuit would result in the simultaneous failure of the redundant isolation valve. We submit the following information in response to the July 18, 1973 letter.
The closure of the containment supply and exhaust purge valves is actuated from separate Engineered Safeguards actuation channels, from a separate control switch for each valse and from a radiation monitoring channel.
Our review of the electrical drawings of Unit 1 established that all circuits are electrically isolated. Thus, in the event of a single failure, isolation of the contain=ent ventilation system will be acco=plished by the redundant valve.
The design of these circuits for Unit 2 has not been cc=pleted.
As a result of.the Commission's letter and the findings on Unit 1, explicit instructions are being forwarded to the designers insuri..g that electrical isolation and physical separation will be incorporated in the completed design.
1584 051 3911080 bk
Mr. James P. O' Reil'.y. Director Page 2 Directorate of Regulatory Operations Therefore, the contain=ent integrity will bc =aintained by the redundant valve in the event of a singic failure in either Unit 1 or Unit 2.
Very truly yours, i,, (- -
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J. G. Miller Vice President kd
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Mr. W. A. Verrochi M
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