ML20086L161
| ML20086L161 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom  |
| Issue date: | 11/09/1973 |
| From: | Cooney M PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC |
| To: | Anthony Giambusso US ATOMIC ENERGY COMMISSION (AEC) |
| References | |
| NUDOCS 8402070435 | |
| Download: ML20086L161 (4) | |
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,8he PHILADELPHIA ELECTRIC COMPANY 2301 M ARKET STREET PHILADELPHI A. PA.19101 h
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N a a((/p>pA s November 9, 1973 N
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, g,$..'.((7 Mr. A. Giambusso N
Deputy Director of Reactor Projects
i United States Atomic Energy Commission
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b Directorate of Licensing
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Washington, D. C. 20545
Dear Mr. Giambusso:
Reference:
Peach Bottom Atomic Power Station - Unit 2 Facility Operating License DPR-44 Docket No. 50-277
Subject:
Abnormal Occurrence On October 31, 1973, two abnormal occurrences were reported in accordance with Section 6.7 2.A of the Technical Specifications, Appendix A of DPR-44 for Peach Bottom Atomic Power Station.
These abnormal occurrences were high reactor water conductivity and apparent failures of three reactor relief valves. Both of these were reported by telephone and telecopy to Region I Regulatory Operations. The details of these abnormal occurrences are discussed below.
High Reactor Water Conductivity At approximately 6:00 a.m. on 10/31/73 following the initial delivery of feedwater to the reactor vessel from the 3 reactor feedwater pump, the conductivity of the reactor water increased from a value of approximately.3 umhos/cm to 34 umhos/cm.
Paragraph 3 6.B.3(a) of the Technical Specifications limits the maximum conductivity of reactor coolant to 10 umhos/cm.
Since this condition was noted, steps were taken to shutdown the reactor and reduce the primary coolant temperature to less than 212 F.
This condition was achieved by 12:42 p.m. on 10/31/73 l
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8'274 COPY SENT REGION J
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- Investigation As a result of the increased conductivity, additional water sample analyses were conducted throughout the plant every 15 minutes from approximately 8
- 50 a.m. to 3:00 p.m.
These included the 4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> frequency reactor water sampics required by Technical Speci fications, Paragraph 4.6.B.2.c.
Reactor water pH remained wi th8n the speci fied limits of Paragraph 3.6.B.c.
Maximum conductivity measured was 34 umhos/cm.
Crud levels increased during the period of high conductivity. A corresponding chloride measurement was 60 ppb.
(un-fi l tered).
The coincidental occurrence of high reactor water conductivity and initial use of portions of the feedwater lines (the B reactor feecipump was used to discharge to the reactor vessel for the first time) would indicate a relationship existed. Although all piping was previously flushed, stagnant water in piping could produce easily transportable crud over a period of time.
Corrective Action Immediate steps were taken to clean up the reactor vessel coolant while reactor power was being reduced to shutdown conditions.
By 2:30 p.m. on 10/31/73 the conductivity of reactor water had been reduced to less than 10 umhos/cm.
Clean-up continued to reduce conductivity and less than 5.0 umhos/cm was achieved by approximately 9:00 p.m. on 11/1/73 Feedwater lines were flushed back to the hotwell of all reactor feedpump discharges prior to the next start-up.
Subsequent use of these lines to the reactor vessel did not cause perturbations in reactor vessel coolant conductivi ty.
Safety Implications Since the reactor was operating at the low power level of 2% at a pressure of 850 psig at the time of the chemical perturbation, it is believed that there was no damage to the reactor internals.
Thi s fac t i s supported by the data which shows that although the conductivity exceeded the 10umhos/cmlimit, the chlorides remained well below the 200 ppb limit with the maximum at 60 ppb on an unfiltered sample. A filtered sample processed within 30 minutes was 36 ppb.
Use of the Reactor Water Clean-up System and establishment of large make-up flow to the reactor via condensate demineralizers were instru-mentalinreducing/cmby2:
the chlorides to 10 b by 1:00 p.m. and conductivity to less than 10 umhos 30 p.m. on 10 1/73
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Relief Valve Bellows 1
At approximately 5:30 a.m. and 7:00a.m.on10/31/73,a bellows failure indication was noted on reactor relief valves 2-71H and 2-71J.
Technical Specification paragraph 3.6,0.2.b permi ts continued reactor operation for 7 days following the malfunction of the safety valve portion of two relief valves. Technical Specification 3.6.D.3 requires an orderly shutdown to atmos-pheric conditions within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> if more than two safety valve functions or relief valves are inoperable. The two indicated failures on 10/31/73, coupled with the indicated failure on 10/23/73, produced the above condi tion.
The reactor was already being shutdown because of the previously mentioned conduc-tivity excursion when the third bellows failure was indicated.
Inves tiga tion Following reactor shutdown, a drywell entry was made and the pressure switches and bonnet caps were removed from the H, J, and K relief valves.
Water was observed in the bonnet assembly of the K valve, 3
indicating that a leak had occurred.
The bonnet assemblies of the H and J valves were found te :e completely dry indicating that no leak existed.
To confirm this, the bellows was pressurized to 1000 psig from the filter port for one hour and found to be tight.
The electrical cable to the pressure switches on both the H and J valves was found to have heat damaged insulation (at the pressure switch connec tor).
Corrective Action The bellows 'O' ring of the K valve was replaced under the supervision of the manufacturer's representative, and the self actuating set-point of the valve adjusted to its nameplate rating. The setpoint adjustment was made using nitrogen applied from the filter port and found to be highly repea table.
The bellows assembly was then leak tested using a soap solution.
The bonnet caps of all three valves were replaced using new ' O' rings.
New, ca librated pressure swi tches were installed on all three valves.
The damaged pressure switch electrical leads to the H and J valves were replaced with cable having a high temperature insulation.
During the week of November 4,1973, a bellows leak alarm was observed on the K, E, and L relief valves.
The reactor was shutdown. An investigation is underway to determine the cause of the alarms.
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e During the current outage, the bellows leak pressure switches of all eleven Target Rock relief valves will be relocated to a cooler area, and will be fi tted wi th high temperature insulation cable.
Safety Implications To date the reactor power level has not exceeded approx-imately 8%. The operability requirement for the minimum number of relief valves is based on reactor operation at 100% power.
Failure of the bellows assemblies at this time during the start-up test program has no safety significa,nce in that suf ficient pressure relief capability was always available.
Very truly yours, 5
n
/k,') Cooneyumf M.,J,.
J Asst. Gcnl. Superintendent Generation Division MJC:1pm cc:
Mr. J. P. O'Reilly Director, Region 1 United States Atomic Energy Comission 631 Park Avenue King of Prussia, PA 19406 e
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