ML20084D641
| ML20084D641 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 01/08/1971 |
| From: | Hoyt H COMMONWEALTH EDISON CO. |
| To: | Morris P US ATOMIC ENERGY COMMISSION (AEC) |
| References | |
| 10258, NUDOCS 8304120147 | |
| Download: ML20084D641 (2) | |
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Q[k-fo-a37 Commonweahh Edison Company ONE FIR S T NATIONAL PLAZA
FOST OFFICE SOX 747
- C H I C A G O, ILLINOl5 60690 Dresden Nuclear Power Station, R.R. #1 Merris, Illinois 60450 Jcnuary 8, 1971 I
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Dr. Peter A. Morris, Director Division of Reactor Licensing U. S. Atomic Energy Cocaission Washington, D.C.
20545
SUBJECT:
License DPR-19 Dresden Nuclear Power Station Unit #2 Section 6.6.C.1 of the Technical Specifications l
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Dear Dr. Morris:
This is to report a condition relating to the operation of the l
station in which on December 30, 1970 the oxygen content of the primary containment rose to 57. 02 by weight as specified by section 3.7.A.5.a.
of the Technical Specification requiring plant shutdown.
PROBELM, INVESTIGATION AND CORRECTIVE ACTION t
The Unit was operating base loaded at approximately 707. of rated power.
The primary containment was operating inerted with nitrogen gas with i
the average 02 content approximately 4.07. by weight.
At approximately 4FM t
on 12-30-70 an increasing trend in both containment pressure and 02 e ntent was noted.
Becat.se of this trend an instrument air Icak within the containment l
l was suspected, f
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An orderly power reduction was then initiated in accordance with l
Section 3.7. A.6. of the Technical Specifict tions.
The limiting condition for operation of 57. oxygen by weight was reacht I at 11:00 PM on 12-30-70.
4 The Unit was taken off line and the reactor placed in the cold i
shutdown condition at 4:15 PM on 12-31-70.
' //l//// Following isolation of the primary system the suspected instrument ir leak was confirmed by manually closing the supply isolation valve and observing a rapid system pressure drop.
Subsequent de-inerting and drywell.
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h entry visually ccufirmed the source of leakage as a failed ( " close y
nipple in the sbpply air line to "1A" main steam isolation valve (MSIV)
{l pilot valve. This nipple failure in no way compromised the ability of that il i
// h 10258F 8304120147 710108 PDR ADDCK 05000237 COPY de.NI REGION
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JAN 191971
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e Dr. Peter A. Mcrris, Director Pat,e 2 January 8, 1971 MSIV to operate since full closure tests t ere performed on all MSIV's during the shutdown on 12-31-70.
The defective nipple was replac(d and the unit critical again on 1-2-71 at 4:30 PM.
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