ML20086K942
| ML20086K942 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom  |
| Issue date: | 05/23/1974 |
| From: | Cooney M PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC |
| To: | Anthony Giambusso US ATOMIC ENERGY COMMISSION (AEC) |
| Shared Package | |
| ML20086K944 | List: |
| References | |
| AO-74-26, NUDOCS 8402070085 | |
| Download: ML20086K942 (3) | |
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May 23, 1974 Mr. A. Giambusso Deputy Director of Reactor Projects United States Atomic Energy Commission Directorate of Licensing 50-277 Washington, D. C.
20545
Dear Mr. Giambusso:
Subject:
Abnormal Occurrence The following occurrence was reported to Mr. R. A. Feil, A.E.C. Region 1 Regulatory Operations Office on May 14, 1974. Written notification was made to Mr. James P. O'Reilly, Region i Regulatory Operations Office on May 14, 1974.
In accordance with Section 6.7 2.A of the Technical Soecifications. Appendix A of nPR hh fnr imit ?
Peach Bottom Atcmic Power Station, the following report is being sub-mitted to the Directorate of Licensing as an Abnormal Occurrence.
Reference:
License Number DPR-44, Amendment Number 1 Technical Specification Reference 2.1.A.1; 2.1.B, and Table 3 2.C
. Report No.:
50-277-74-26 Report Date:
May 23, 1974 Occurrence Date: May 13, 1974 Facility:
Peach Bottom Atomic Power Station R.D. 1, Delta, Pennsylvania 17314 Identification of Occurrence:
Incorrect calibration of recirculation loop flow trans-mitters FT-2-110A thru D.
Conditions Prior to Occurrence:
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Plant operating at about 80% power.
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May 23, 1974 Page 2
' ' Description of Occurrence:
During plant startup testing, an investigation into the disagreement in flow indication between the recirculation loop in-strumentation and the core flow instrumentation disclosed that the recirculation flow transmitters were not calibrated to the proper range.
Designation of Apparent Cause of Occurrence:
Use of inappropriate range for the flow transmitters.
Analysis of Occurrence:
Investigation into the disagreement between indicated core flow as derived from jet pump flow measurement, calculated core flow as derived from pump curves and measured pump head, and indicated re-circulation loop flow disclosed that dication was higher than actual flow. the recirculation loop flow in-This was determined to be due to calibration of the flow transmitters to the wrong range.
This higher flow signal is supplied to the APRM's and RBM's.
Thus, the APRM flow biased scram and rod blocks, and the RBM flow biased rod u'luuka, were higher tnan the limiting safety system settings given in the Technical Specifications.
Additionally, a scram would have occurred atThe error was about 7% above setpoint.
about 100% power due to a
" scram clamp" which had been placed in service for the startup period to ensure that scram settings were conservative. Although this flow measurement error resulted in exceeding a safety system setting, by the aforementioned 7%, there was minimal significance because'the reactor would have scrammed at about 100% power. The bases to the Technical Specifications, which refers to Section 14 of the FSAR, states that "with a 120 percent scram trip setting, none of the abnormal operational transients analyzed violate the fuel safety limit and there is a sub-stantial margin from fuel damage. Therefore, use of a flow-biased scram provides even additional margin."
Corrective Action:
Because of the_ work involved in repairing the flow _trans-mitters, the gains in the APRM and RBM flow converters were readjusted immediately to provide a flow Lsignal of the proper value thus resulting in flow biased scram and rod blocks of the correct value.
Recalibration of the recirculation loop flow transmitters to the proper range as determined by the startup test program was accomplished during the plant shutdown on May 18, 1974. The entire instrumentation loop'was 1'
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Page 3 May 23, 1974 A.' Corrective Action: (continued) readjusted such that flow indication and signals to the APRM and RBM instrument channels are proper.
Failure Data:
None previous.
Very truly yours,
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M.f.'Cooney J
Ass't Gen'1 Superintendent Generation Division cc:
Mr. J. P. O'Reilly Director, Region 1 United States Atomic Energy Commission 631 Park Avenue King of Prussia, PA 19406 l
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