ML20151C158
| ML20151C158 | |
| Person / Time | |
|---|---|
| Site: | Oyster Creek |
| Issue date: | 01/07/1974 |
| From: | Maloney J JERSEY CENTRAL POWER & LIGHT CO. |
| To: | |
| References | |
| AO-50-219-74-1, NUDOCS 8103040737 | |
| Download: ML20151C158 (4) | |
Text
.-,
Report Dates-
'1/7/74 -
Occurrence:
1105 u
s i-OYSTER CREEK NUCLEAR GENERATING STATION FOPXED RIVER, NEh' JERSEY 08731 Abnomal Occurrence
- Report No. 50-219/74/ 1-
'IDEhTIFIC'ATION Violation of the Technical Specifications, paragraph 2.3.7,
'0F OCCURRENCE:
- Low Pressure !!ain Steam Line Pressure Switch (RE23C) was found to trip at a pressure less than 850 psig.
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'Ihis event is considered to be an abnomal occurrence as de-fined in the Technical Specifications, paragraph 1.15A CONDITIONS PRIOR Routine Shutdown TO OCCUXPINCE:
X Steady. State Power Operation Hot Standby Cold Shutdown Load Otanges During Refueling Shutdown Routine Power Operation
] Operation Routine Startup Other (Specify)
'Ihe cajor plant paranotcrs at the tice of the event were as follows:
Power - Core, 1830 E t
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Elec., 642 We' (g)
Flow '- Recirc., 60.2 X10' #/hr Pced.,
6.77 X10' # hr Stack Gas - 24,000' pCi/Sec DESCRIPTION On Friday, January 4,.1974 at 11.05, while perfoming surveil-0F OCCURRD;CE:
lange testing on the four Hain Steam Line Low Pressure Switches, RE23A, B, C, and D, RE23C was found to trip at 841 psig which is 9 psig below tho' r.inimum required setpoint of 850 psig. 'Ih e other pressure switches were found to trip at the following v
values:
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g.103o40737 RE23D - 851 psig
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i APPARENT.CAUSE Design Procedure OF OCCURTS CE:
~ Hanufacture Unusual Service Condition Installation /
Inc. Environmental Construction Cotponent Failure Operator Other (Specify)
At this time, the cause of this event, which has occurred in the past, has yet to be determined.
In the past, the manu-facturer had been contacted and had informed plant personnel that the problem of setpoint drift has been recognized with this type of instrument.
An investigative program'has been initiated by the annufacturer, but no forn:1 report on the results issued as of yet.
ANALYSIS OF As indicated in the bases of the Technical Sp'ecifications, "The OCCUPJINCE:
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low pressure isolation of the Main Steam Lines at 850 psig was provided to give protection.against fast reactor depressuriza-tion and the resulting rapid cooldowr of the vessel. Advant-age was taken of the scram feature which occurs when the Hain Steam Line Isolation Valves are closed to provide for reactor shutdown so that high power operation at low reactor pressure does not occur, thus providing protection for the fuel cladding inter,rity safety limit."
With regards to power opefat on below 850 psig and the atten-dant offects on the fuel cladding integrity safety limit, power level must be limited when pressure is less than 600 psig or r-
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i flow is Icss than 10% to 354 FNt or.opproxientely 18.3% of rat ed.
As stated in the Technical Specifications, "The value is applicable to ambient pressure and no flow conditions.
For any greater pressure or flow conditions there is increased margin." The fuel cladding integrity safety limit curve has been developed and is applicabic for pressure in excess of.
600 psig.
Therefore, whether a reactor scram occurs at 850 psig or 841 psig has little safety significance since no severe restrictions on critical heat flux are icposed until pressure is less than 600 psig.
In addition, the remaining three (3) sensors were operable and would ha"e performed the protective action, if required and at the proper setpoint of.
1.850 psig.
CORRECTIVE The pressure switch (RS23C), upon discovery of this condition, ACTION:
was reset to 850 psig to conform with the Technical Specifi-i cations.
Recommendations to correct the abnormal occurrence and pre-vent repetition of the occurrence and of similar occurrences will be provided after review by the Plant Operations Review Committee.
FAILURD DATA:
Hanufacturer data pertinent to these switches are as follows:
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Abnormal,0ccurrence Report !!oi, 50-210/74/ 1 _ '
Page 4-t Heletron Corp. (subsidiary of Barksdale)
- Los Ange30s, California Pressure Actuated Switch Model 372 Catalog #372-6SS49A-293
< - Range 850 G Dec.
Proof Psi.1750 G.
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