ML20085J922
| ML20085J922 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 05/21/1974 |
| From: | Stephenson B COMMONWEALTH EDISON CO. |
| To: | Oleary J US ATOMIC ENERGY COMMISSION (AEC) |
| Shared Package | |
| ML20085J926 | List: |
| References | |
| 365-74, NUDOCS 8310190206 | |
| Download: ML20085J922 (2) | |
Text
f.g Ccmmopy/ealth Edison t ni One First/ pal Plaza. Cnicago. Imnois i~% /
Addrcss f~rdy to: Post Olkco Box 767
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Chicago, !!!ihois 60690 BBS Ltr.#365-74 Dresden Nucicar Power Station R. R. #1 Morris, Illinois 60450 May 21, 1974 lf U 4 L
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" S. };,' x Mr. J. F. O' Leary, Director 0
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U. S. Atomic Energy Ccc:nission p g#h Washington, D. C.
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SUBJECT:
EICENSE DPR-25, DRESDEN i:UCLEAR PO'JER STATION. UNIT #3, REPORT OF AENOFAL OCCURRENCE PER SECTION 6.6.B. I.a OF THE TECHNICAL SPECIPICATIONS.
_ EXCESSIVE LEAKAGE TilRU MSIV 3-202-1B.
References:
- 1) Notification of Region III of AEC Regulatory Operations Telephone: F. Maura, 1600 hours0.0185 days <br />0.444 hours <br />0.00265 weeks <br />6.088e-4 months <br /> on May 16, 1974 Telegram: J. Keppler, 1620 hours0.0188 days <br />0.45 hours <br />0.00268 weeks <br />6.1641e-4 months <br /> on May 16, 1974
- 2) Dwgs: P&ID M-345
Dear Mr. O' Leary:
liais letter is to report a conoition relating to the operation or the unit on May 15, 1974. On this date, during local leak rate testing of the tuain steam isolation valves, valve IB was found to have leakage of 24.8 scf/hr. This malfunction is contrary to section 4.7.A.2.f(2)(c) of the Technical Specifications which requires that the maximum allowable leakage for any one main steam line isolation valve is 11.5 scf/hr @ 25 PSIG.
PROBLEM On Iby 15, 1974, local leak rate-tests were being conducted on Unit 3 main steam isolation valves. A test on valves 13 and 2B revealed a'lcakage rate of 30.8 sef/hr.
On March 14, 1974,'2B was tested and found to have a leakage rate of 6.0 scf/hr. This implies 1B has a leakage rate of 24.8 scf/hr.
At the time of the occurrence, Unit 3 was in its second :r.ajor outage and primary containment was not required.
INVESTICATION' It was decided that both valves 203-1B & 2B internal components would be inspected to determine the source of the leakage.
Upon inspection, valve 203-2B was found to'have a warped valve seat and valve IB was checked and found to have hairline cracks in the stellite overlay on the disc.
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r Mr. J. F. O' Leary May 21, 1974 CORRECT 1'E ACTIONS The corrective actions taken on MSIV 2B was to lap the seating surfaces and reinstall. As a result of the hairline cracks, MSIV IB will be fitted with a new disc which will be lapped and reinstalled. The leak test for these valves will be included in the pri: nary containment leak rate test report to be submitted for this outage. The other six MSIV's have been leak tested and found satisfactory.
, EVALUATIONS The failure of MSIV 1B did not offect the safety of plant personnel or the public because the back-up valve in this line, M31V 2B, had leakage within Technical Specification limits. A review of MSIV probleus has verified that this is the first failure of this type.
It is therefore concluded that the corrective action stated above is adequate.
Sincerely, ~
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B.'E. Stephenson Superintendent LLs;ii:du l