ML20086K338
| ML20086K338 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom  |
| Issue date: | 10/26/1974 |
| From: | Cooney M PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC |
| To: | Anthony Giambusso US ATOMIC ENERGY COMMISSION (AEC) |
| Shared Package | |
| ML20086K335 | List: |
| References | |
| AO-74-44, NUDOCS 8401270034 | |
| Download: ML20086K338 (2) | |
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[Q. %f 7 PHILADELPHIA ELECTRIC COMPANY 2301 MARKET STREET PHILADELPHI A. PA.19101 121518414ooo October 26, 1974 V'" R N.
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Mr. A. Giambusso 7'jj Deputy Director of Reactor Projects f
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Directorate of Licensing O.0 Washi ng ton, D.C.
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Dear Mr. Giambusso
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Subject:
Abnormal Occurrence b
,V The following occurrence was reported to Mr. Walt Baunack, A.E.C. Region I Regulatory Operations Office on October 17, 1974.
Written notification was made to Mr. James P. O'Reilly, Region 1 Regulatory Operations Office on October 17, 1974.
In accordance with Section 6.7.2.A of the Technical Spect fications, Appenc A of DPR-44 for Unit 2 Peach Bottom Atomic Power Station, the following report is being submitted to the Directorate of Licensing as an Abnormal
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Occurrence:
Reference:
License Number DPR-44, Amendment Number 1
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Technical Specification Reference 3.6.D.1 i
Report No.:
50-277-74-44 Report Date:
October 26, 1974 m
Occurrence Date: October 16, 1974 '
Facility :
Peach Bottom Atomic Power Station R.D. #1, Delta, Pennsylvania Identification of Occurrence:_
4-Relief valve opened causing reactor depressurization.
Condi tions Prior to Occurrence:
Unit 2 operating at 64% power, 708 MWe, primary coolant pressure 935 psig.
Description of Occurrence:
s Relief Valve 71E inadvertently opened during power operation at 64% power. The recirculation pumps were manually run back to minimu.n speed and the '88 recirculation MG set breaker was manually tripped.
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8401270034 741106
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Mr. A. Giambusso
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October 26, 1974 Page 2 A manual reactor scram and turbine trip were initiated approximately
~ 0 minutes af ter the relief valve inadvertently opened.. This tripped 2
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'A' recirculation MG set breaker ano fast transferred the auxiliary power to the startup source.
The relief valve reclosed at approximately 350 psig approxitnately 30 minutes af ter it opened.
Reactor pressure never exceeded 935 psig during this transient.
Designation of Apparent Cause of Cecurrence:
Pilot valve disc icakage pressurized the second stage piston thus opening the second stage valve disc and the main valve.
Refer to FSAR Figure 4.4.2.
Analysis of Occurrence:
When the transient occurred, plant procedurca proved to be adequate to safely shutdown the plant. Automatic actions following the manual scram and turbine trip were as expected.
An analysis of the temperature transient associated with this occurrence showed that no reactor vessel temperature limits were exceeded and the actual cooldown rate was less than 1000F/hr. Torus water tempo.rature rose to approximately 1380F as measured by the torus thernocouple closest to the 71E relief valve exhaust point. This is significantly below the 281 F design temperature of the torus.
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Since the temperature and pressur.e transient experienced by the reactor vessel was less severe than conditions used in the reactor vessel design and since no radiation releases occurred as a result of the transient, no safety significance is associated with this occurrence.
Corrective Action:
The pilot valve disc was machined and the pilot valve seat l a'pped.
Bench tests of the pilot valve and secondary valve indicated no leakage. During the subsequent reactor startup, proper valve opera-tion and rescating was proven by conducting the " Relief Valve Manual Actuation" surveillance test at approximately 150 psig and rated reactor pressu re.
3 Failure Data =
c Previously reported Abncemal Occurrences concerning Unit 2 relief v3 ves were Report Numbers:
50.-277-74-12, 16 and 17.
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Very truly yours,
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M.,.Cooney!
Asst. Gen 1. Supt.
cc: Mr. J. P. O'Reilly Generation Division Director, Region i Uni ted States Atomic Energy Corrmission
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