ML19241A639
| ML19241A639 | |
| Person / Time | |
|---|---|
| Site: | Oyster Creek |
| Issue date: | 05/30/1979 |
| From: | Eisenhut D, Eisenhut D Office of Nuclear Reactor Regulation |
| To: | Gilinsky V, Hendrie J, Kennedy R NRC COMMISSION (OCM) |
| References | |
| REF-10CFR9.7 NUDOCS 7907090024 | |
| Download: ML19241A639 (10) | |
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Daily Highlight - Oyster Creek On May 2,1979, during the perfomance of surveillance tests a false reactor high pressure scram occurred at the Oyster Cree % Nuclear Generating Station. The events that followed resulted in the shutdown of all three feecwater puu:ps.
During the loss of feedwater transient all five of the recirculation loop pump discharge valves were closed. All five discharge valves 2 inch bypass lines were open, but did not provide a large enough flow of water froa the outside of the core region, the annulus, to the core region. As a result, the water was boiling away 1. the core regios faster than it was being returned through the bypass lines and the water level above the core decreased below the low-low-low level alam.
When one of the recirculatica lep pump discharge valves was reopened.
the increased flw from the annulus to the core region raised the wr.V.er level above the low-low-low level al tm.
Existing Technical Specification defines the low-low-low level as a Safety Limit when the reactor is in the shutdown condition. Even tnough the reactor code switch was not in the shutdown mode, the May 2,1979 eunt has been regarded as if a Safety Limit was violated. Therefore, the reactor was<placed in the cold shutdown condition and the licensee and the NRC perfor:ned a thorough evaluation of the minirum water level that occurred during the event to detemine if any fuel damage had occurred.
In additioti, the NRC conducted an evaluation of the folled up actions proposed by the licensee to prevent recurrence.
The 'mensee notified Region I of the event at approximately 3:20 p.ms NRR was first notified of the event by a Region I, I&E Inspector at approximately 5:20 p.m.
On May 3, '1979, four NRR esployees joined members of the Office of Inspection and Enforcement at the site to review the event and detemine the.str.*us of the plant.
By May 3,1979 it was confimed that the reactor was in a safe configuration and calculations were initiated to detemine if any cure damage had occurred.
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Coolant and gas activity analysis indicated no fuel damage. The initial review activities centered around detailed descriptions of the event as a function of.
time. The fact-finding was pursued in detail where cperator actions, equipment status, or equipment performance dirfered from expectation. The primary source of information relative to operator actions was obtained from interviees; the event recorder and other instrumentation records provided infomation regarding equipment perfor: nance.
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- Fact finding activities between the Headquarters staf f and the WRC team at Oyster Creek was supplemnted by inforwition obtained frca the Nuclear Steam Supply System and fuel suppliers.
A status report was issued by the staff which described the event in detail, discussed potentially bounding events previously analyzed for Oyster Creek, sumarized the status of calculations and seasurements indicating no core damage, identified the significant unanswered questions, described planned actions, and sumarized the findings to date.
It was detemined that the implications of the event appear limited to non, jet-pug, forced circulation BWRs. All reactors of this type were detemined to be shutdown for other reasons.
The licensee, and his consultants, ret with the staff on May 9 to describe the event in detail, to assess the condition of the core, and to discuss the requirements for restart.
Many issues were clarified and the addit 1onal inforcation requirements were identified.
The possiole generic ic:plications of the Oyster Creek event have been considered.
It was determined that cnly two other facility designs, Nine Mile Point I aad Lacrosse, were susceptible to a similar event.
The ircediate requirefnents -being imposed on Oyster Crect will also be implemented at these facilities prior to their start-up.
Conclusion Our SER of the Oyster Creek event has been cos1pleted. The SER discusses the minimum water level experienced in the reactor vessel and the fuel conditions. The following three requirements were made conditions of restart:
1.
Establish the triple low level as a Safety Limit for essentially all modes of reactor operations.
2.
Establish a Safety Limit tc require at least to recirculation loop discharge and suction valves to rw. sin in the full open position.
3.
Agree to propose by June 1,1979 a limiting sufety systs setting tc, automatically initiate operation of the isolation condenser on a low-lcw water level signal.
The SER also reconrnended that the licensee consider surveillance program and level instrument improvecents.
It was concluded that no procedure violations occurred, no fuel damage resulted frca the event, and the facility could be safola returned to operation.
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