ML19209A187
| ML19209A187 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 09/07/1979 |
| From: | Vassallo D Office of Nuclear Reactor Regulation |
| To: | Eisenhut D Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML19209A188 | List: |
| References | |
| NUDOCS 7910030087 | |
| Download: ML19209A187 (2) | |
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Cocket File EHylton LShao CELD t wr pr o LEngle RVollmer ACM ORS #4 Rdg JStolz TJCarter Reg. Files September 7, 1979 Memo File SVarga WRussell Public Info Proc.
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'RReid HRDenton LShao WGacraill DSS Docket No. 50-368 SGrimes DVassallo
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JRMiller, COR DEisenhut MPA a
MEMORANDUM FOR: Carrell G. Eisenhut, Acting Director, Division of Operating Re, actors FRCM:
D. B. Vassallo, Acting Director, Division of Project Management
SUBJECT:
ARXANSAS NUCLEAR ONE UNIT 2
SUMMARY
OF SIGNIFICANT CPERATING EVENTS TO DATE 7/18/78 Issuance of Operating License No. NPF-6, Modes 5 & 6 only 9/1/78 Authorization for Operational Modes 3 & 4 9/16/78 An unusual sequence of events occurred affecting both ANO-1 and ANO-2.
It resulted in degraded engineered safety features for Unit 2 and was reported to Congress in NUREG-0090 Vol. 2, No.1, Jan-Mar 1979, as an Abnor nal Occurrence.
The sequences started with a trip of ANO-1 which transferred offsite electrical loads to a Startup Transfamer (ST) #1; ANO-2 offsite pcwer was being fed through Startup Transformer (ST) #3; the Auto-Transformer feeding ST 11 and ST #3 had its protective relays set for ANO-1 operation only; these protective relays tripped and cutoff power to ST #1 and #3, leaving only ST #2 as the only offsite source for coth Units 1 and 2.
The subsequent voltage drop properly dis-connected the engineered safety features (ESF) bus. Hcwever, an.
incorrect inverter pcwer alignment to the ESF bus only,resulted in failure of pcwer to two vital instrument buses which in turn resulted in emergency safeguards actuation and premature actuation of the Recirculation Actuation System that allowed 60,000 gallons of refueling borated water to transfer from the Refueling Water Tank to the centain-ment sump.
Although Unit 2 was preccerational and has no fission product inventory, this event is considered an Abnomal Occurrence because if a LOCA were to cccur at power, the above sequence of events could have resulted in degraced ECCS perfomance.
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P00[03GH1 Darrell G. Eisenhut 11/7/78 Emergency Diesel Generator f2 trip on low lube oil pressure with inspection revealing damage to rod and main bearings 12/4/78 NRC authurization to proceed to Mode 2 (Critical to <5% power) 12/5/78 Initial criticality attained at 1455 hours0.0168 days <br />0.404 hours <br />0.00241 weeks <br />5.536275e-4 months <br /> 12/14/78 Zero Power Physics Tests completed 12/14/78 NRC authorization to proceed to Mode l 12/26/78 Initial electric generation occurred at 2000 hours0.0231 days <br />0.556 hours <br />0.00331 weeks <br />7.61e-4 months <br /> 4/15/79 Emergency Diesel Generator #2 failed during routine surveillance test; failure due to same problem that occurred on 11/7/78 Emergency Diesel Generator #2 declared operable 5/11/79 5/13/79 Initial decision to replace all of original main steam code relief valves with Crosby valves 5/25/79 Crosby main steam relief valve installation complete 6/13/79 1.oss of Off-Site Power Caused by Faults in Unit 2 Hign Voltage Distribution System The only AbnorN T Occurrence was the 9/16/78 event.
D. 3. Vassallo, Acting Director Division of Project Management Office of Nuclear Reactor Regulation
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