ML20086L171
| ML20086L171 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom  |
| Issue date: | 04/26/1974 |
| From: | Cooney M PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC |
| To: | Anthony Giambusso US ATOMIC ENERGY COMMISSION (AEC) |
| Shared Package | |
| ML20086L173 | List: |
| References | |
| AO-74-22, NUDOCS 8402070446 | |
| Download: ML20086L171 (2) | |
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PHILADELPHIA ELECTRIC COMPANY
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- M April 26,1974 Mr. A. Giambusso Deputy Director of Reactor Projects United States Atomic Energy Commission Directorate of Licensing Washington, DC 20545
Dear Mr. Giambusso:
Subject:
Abnormal Occurrence The following occurrence was reported to Mr. Ed Greenman, A.E.C.
Region I Regulatory Operations Office on April 17, 1974. Written noti-fication was made to Mr. James P. O'Reilly, Region I Regulatory Operations Office on April 17, 197h.
in aceneriance with sectinn 6 7 7.A nf tha Technical Specifications, Appendix A of CPR-44 for Unit 2 Peach Bottom Atomic Power Station, the following report is being submitted to the Directorate of Licensing as an Abnormal Occurrence.
Reference:
License Number DPR-44, Amendment Number 1 Technical Specification 3 5.C.1 Report No.:
50-277-74-22 Report Date:
April 26,1974 Occurrence Date: April 16,1974 Facility:
Peach Bottom Atomic Power Station R.D. #1, Delta, Pennsylvania 17314 Identification of Occurrence:
HPCI tripped during reactor vessel injection test.
Conditions Prior to Occurrence:
Plant shutdown following a planned turbine trip and scram from 50% power.
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April 26,1974 Paga 2 Designation of Occurrence:
As part of the start-up test program, an HPCI system test which delivers water to the reactor vessel is required.
This test was performed on April 16, 1974 following a planned turbine trip and reactor scram from the 50% power level. Upon automatic initiation, the HPCI turbine isolated.
Isolation was caused by a high steam flow con-dition to the turbine. High steam flow was sensed by a differential pressure switch connected to an elbow tap flow element in the steam supply to the HPCI turbine. The isolation was immediately reset by the operator. This permitted the HPCI to restart and successfully injected water to the reactor vessel at rated flow. Data taken during this test indicated additional control adjustments are required.
Designation of Apparent Cause of Occurrence:
Data taken during the HPCI injection test shows that turbine acceleration rate during the initial start was significantly greater than during the restart. This infers that the steam flow during the initial start was also significantly greater than during the restart.
Analysis of Occurrence:
The initial isolation of the HPCT cyctem rinring tha injactinn test has no safety implications in that the system was demonstrated immediately to be capable of injecting water to the reactor vessel.
Start-up testing is performed for the purpose of identifying and correcting minor control problems with engineered safeguard systems prior to achieving reactor power icvels where design system response is required to mitigate accidents.
Corrective Action:
The calibration of the HPCI governor ramp generator module was checked.
It was found that the idle setting of the ramp generator was set such that the turbine control valves, which at the time of stop valve opening are opening wide, would not begin to close at the pres:ribed speed of 700 r.p.m.,
but rather at some higher speed.
In addition, the ramp time was found to be set from idle voltage to ramp generator maximum voltage, rather than from idle voltage te that voltage which the signa! converter generates in response to a maximum signal from the flow controller (i.e., a lower voltage than the ramp generator l
maximum voltage). This resulted in a shorter ramp time and steeper ramp slope. The combination of these two findings retarded control valve closure such that high steam flow was established. The cali-l bration of the ramp generator was corrected and a system operability check was performed at approximately 150 psig reactor pressure. Punp l
and turbine operability was then verified at rated pressure followed i
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Mr. A. Gia.mbusso April 26,1974 Page 3 o
by five simulated automatic initiation quick starts using the pump test loop flow path.
It is expected that these changes to the control system will avoid tripping during starting period. Addi tional testing, how-ever, will be conducted when condi tions permi t.
Failure Data:
No previous similar HPCI failures have been experienced.
Very truly yours,
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VtW' M. J. Cooney ;
Asst. Gent. Superintendent Generation Division cc:
J. P. O'Reilly Director, Region 1 United States Atomic Energy Commission 631 Park Avenue King of Prussia, PA 19406 t
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