ML20249B494
| ML20249B494 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 07/22/1976 |
| From: | Dreher F, Roy G, Thompson D NRC OFFICE OF INSPECTION & ENFORCEMENT (IE) |
| To: | |
| References | |
| PNO-76-127, NUDOCS 9806230220 | |
| Download: ML20249B494 (1) | |
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PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE-PNO-76-127 This preliminary notification constitutes EARLY notice of an event of POSSIBLE safety or public interest significance. The information presented is as initially received without verification or evaluation and is basically all t_ hat is known by IE staff on this date.
Facility:
Millstone Point 2 (DN 50-336)
Subject:
UNPLANNED REACTOR SHUTDOWN On July 20, 1976 the licensee identified and reported a potential unreviewed safety question. This involved a condition wherein control circuit fuses could blow when starting motors of safety related equipment under a condition where the overall voltage in the plant is reduced. Safety related equipment fed through these fuses would then be inoperable and if a need for this equipment occurre-eith the plant in this condition the equipment would not operate To accommodate this potential unreviewed safety question on a temporary basis, the ESAS setting (ESAS is that setting where the sequence of l
load shedding, diesel start and engineered safeguard load pickup begins) l which was normally set at 70% of nominal voltage, was raised to 90%.
t This was accomplished on July 20, 1976.
On July 21, 1976, during start of a circulating water pump, voltage dropped below 90%, which was the new ESAS setting. As designed this resulted in a reactor trip, load shedding, diesel start, and load pickup sequencing. However, on load pickup the voltage again dropped below the ESAS setting which caused the load shedding c3rcuitry to reactivate.
The reactor was safely shutdown; however, due to load shedding, cooling water flow to the reactor coolant pump (RCP) seals was lost for several minutes. Two of the three seals on one RCP appear to have been damaged and will be replaced. The remaining seal remained intact.
The shutdown is expected to last for seven days to repair the pump seal, perform other ij routine maintenance, and resolve the potential unreviewed safety goestion described above.
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Media interest is expected because of close attention paid to operations O
at Millstone Facilities. The State of Connecticut has been informed. A press release is not planned.
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!i This information is current as of 4:30 p.m. on July 21, 1976.
Contact:
FADreher, IE x27261
Chairman Rowden Commissioner Mason S. J. Chilk, SECY t
Commissioner Gilinsky C. C. Kammerer, CA G. F. Murphy, JCAE Commissioner Kennedy L. V. Gossick, EDO E. Volgenau, OIE '
J. A. Harris, PA j
B. C. Rusche, NRR H. K. Shapar, ELD T. J. McTiernan, AIA K. R. Chapman, NMSS R. G. Ryan, OSP' Transmitted: PBldg /O-H St /d Nf NMBB / I Luge N
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9806230220 760722 PDR I4rE g
PNO-76-127 PDR
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