ML19343C220
| ML19343C220 | |
| Person / Time | |
|---|---|
| Site: | Oyster Creek |
| Issue date: | 07/26/1974 |
| From: | JERSEY CENTRAL POWER & LIGHT CO. |
| To: | NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| References | |
| AO-50-219-74-41, NUDOCS 8103040442 | |
| Download: ML19343C220 (3) | |
Text
.ersey CentrL Power & Light Company MADISON AVENUE AT PUNCH BOW 1. ROAD
- MORRISTOWN,N.J.07960
- 201539-6111
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OYSTER CREEK NUCLEAR GENERATING STATION FORKED RIVER, NEW JERSEY 08731 Abnormal Occurrence Report No. 50-219/74/41 Report Date July 26,1974 Occurrence Date July 19, 1974 Identification of Occurrence Violation of the Technical Specifications, paragraph 2.3.7, main steam line low pressure switches RE23C and D were found to trip at. pressures less than the minimum required value of 860 psig. H is event is considered to be an abnormal occurrence as defined in the Technical Specifications, paragraph 1.15A.
Conditions Prior to Occurrence ne plant was at steady state power with major parameters as follows:
Power:
Reactor, 1895 MWt Electric, 641 MWe 6 lb/hr Flow:
Recirculation, 57.6 x 10 Feedwater, 7.08 x los Ib/hr Reactor Pressure:
1020 psig Stack Gas:
16,000 pCi/sec Description of Occurrence On Friday, July 19,1974, at 1023, while performing a routine surveillance test on the four main steam line low pressure switches, it was discovered that switches RE23C and D tripped at 855 and 853 psig, respectively. These values are below the minimun required trip point of 860 psig which is derived by adding to the Technical S ecification limit of 850 psig, a 10 psig head correction factcr.
I wwga P00R ORIGINAL
7 Abnorn 1 Occurrence Report No. 50-219/74/41 Page 2
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De "as found" and "as Ic'ft" switch setti,nts were:
l "As Found" Settings "As left" Settings RE23A 860 psig 860 psig RE23B 860 psig 860 psig RE23C
. 855 psig 860 psig RE23D 853 psig 861 psig Apparent Cause of Occurrence ni: event is considered to be reportable because of the lack of set point tolerances in the Technical Specifications.
Analysis of Occurrence
,As indicated in the bases of the Technical Specifications, "The low pressure isolation of the Flain Steam Lines at 850 psig was provided to give protection against fast reactor depressuri:ation and the resultant rapid cooldown of the vessel. Advantage was taken of the scram feature which occurs when the Flain Steam 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 integrity safety limit."
4 The adverse consequences of reactor isolction occurring at reactor pressure approximately 7 psig below the specified minimum galue of 860 psig is limited to those effects attendant to a greater than normal reactor cooldown rate. The fuel cladding integrity safety limit only comes into effect for power operation at reactor pressures less than 600 psig or for power operation greater than 354 FMt with 1 css than 10*6 recirculation flow. Therefore, the consequences of a 7 psig lower than normal reactor isolation and scram set point has no threatening effect whatsoever en the fuel cl~ adding integrity.
The effects of a too rapid cooldown due to the lower isolation pressure are inconsequential since there is Icss than l'F difference between the saturation temperature for 350 psig and 843 psig, i
Corrective Action Set point accuracy and tolerance in not only these instruments but in others E well are under investigation by Jersey Central Power T Light Company, GPU Service Corporation, and General Electric Company personnel as described in Abnormal Occurrence No. 50-219/74/35.
P00R ORlblNAl.
Abnormal Occurrence Report No. 50-219/74/41 Page 3 Failure Data Manufacturer data pertinent to these switches are as follows:
Meletron Corporation (subsidiary of Barksdale)
Los Angeles, California Pressure Actuated Switch Model 372 Catalog No. 372-6SS49A-293 Range 20-1400 psig Proof Psi 1750 G Previous abnormal occurrence reports involving these switches are:
1.
Letter to Mr. A. Giambusso from Mr. D. A. Ross, dated December 24, 1973.
2.
Abnormal Occurrence Report No. 50-219/74/1 3.
Abnormal Occurrence Report No. 50-219/74/9 4.
Abnormal Occurrence Report No. 50-219/74/10 5.
Abnormal Occurrence Report No. 50-219/74/12 6.
Abnormal Occurrence Report No. 50-219/74/22 7.
Abnormal Occurrence Report No. 50-219/74/35 8.
Abnorual Occurrence Report No. 50-219/74/37 P00R ORIGINAL 9
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