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i 631 Park Avenue King of Prussia, Pennsylvania 1%06 1
FEB 6 1974 J. J. McDocar Administrative Officer JERSEY CENTIAL POWER AND LIGHT COMPANY (DN 50-219)
Effective inumsdiately, the telephone listing for JCP&L Corporate contacts has been changed as follows:
1 (Area Code 201) 539-6111 Please arrange to have our records changed accordingly.
E. G. Greenman Reactor Inspector 4
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, OYSTER CREEK NUCLEAR GENERATING STATION FORKED RIVER, NEW JERSEY 08731
. Abnormal Occurrence Report No. 50-219/74/9 Re' port Date:
-February 6, 1974 Occurrence Date_:
January 31, 1974 Identification of Occurrence:
Violation of the Technical Specifications,' paragraph 2.3.7, low pressure main steam line pressure switches. (RE23A and D) were found to trip at pressures less than the specified value (850 psig plus 10 psig for head This event is. considered to be an abnormal. occurrence as
. corre. tion).-
c defined in, the Technical Specifications, paragraph -1.15A.
Conditions Prior to Occurrence:
The plant was. operating at steady state power.
The major plant parameters at the time o'f the event were as follows:
Power - Core, 1902.9 MWt Flow-Recire.,57.9x10jg)
Elec., 669 MWe
^1bm/hr 6 lbm/hr Feed., 7.2x10 Stack Gas - 23,230 pC1/sec Descripcion of Occurrence:
31,1974, at 1320, while performing routine surveil-On Thursday, January lance testing 'on the four main steam line low pressure switches, it was discovered that RE23A and RE23D tripped at. 858 psig and 856 psig, respec--
This:was 2 psig and 4 psig below the set point of 860 psig.
tively.
Although the Technical Specifications call for a main' steam line low pressure set point of. 850 psig, the set point for the switches is 860 psig to account for the difference in head between the switches and the main steam-line.
As found switch settings were:
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'lest #1 Test #2
-RE23A-860.psig 858 psig cRE238.
^860 psig-
-860 psig
.RE23C 863 psig-862 psig pup,_3 99
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Abnormal Occurrence No. 50-219/74/9 Page 21 Repeatability of the sensors was' checked by observing two consecutive trip points.
The pressure switches'were then recalibrated and checked to actuate as
. follows:.
Test #1
. Test #2-4 RE23A 861 psig L 861 psig RS23D 862 psig 861 psig Apparent Cause of Occurrence:
Design and unusual service conditions are factors contributing t cause of this event.
The steps. proposed to work is in progress. to formulate a final solution.
50-219/74/1.
achieve this end were delineated in Abnormal Occurrence Report No.
Analysis of Occurrence _:
As indicated in the bases of the Technical Specification, "The low pres'sure.
isolation of the main steam lin'es at 850 psig was provided to give pro-tection against fast reactor depressurization and the resultant rapid cool-Advantage was taken of the scram feature which occurs
'down of the vessel.
when the main 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. "
The adverse consequences of reactor isolation occurring at reactor pressure approximately 4 psi below the specified minimum value o
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The fuel cladding integrity safety limit only comes into effect for power operation greater than 354 MWt with less that 10% recirculation down rate.
flow. l Therefore, the consequences of a 4 psi Iower than normal reactor isolation and scram set point has no threatening effect whatsoever on the i
fuel' cladding integrity.
The effects of a too rapid cooldown due to the lower isolation pressure are inconsequential since there is less than l'F difference between the -
saturation temperature for 860 psig, and 856 psig.
The adverse: safety effect of,RE23A and~ RE23D actuating at the as found The other two sensors, I
. pressures is in the loss of system redundancy.
l RE23B and C, would have functioned normally.
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' i Abnormal: Occurrence No.-50-219/74/9
- Page_3 Corrective' Action'
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Continuing corrective actions being taken.at this time are as follows:
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'1. ' Investigation ;is being conducted into the basis for the
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steam'line low pressure setting of 850 psig.
Development of a
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Technical Specification change to' lower the set point will follow if-results of transient. analyses indicate this possibility.
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Vendor recommendations to possibly reduce or eliminate the
_ sensor set point change problem will-be evaluated as soon as they are available.
- 3. - A request has been initiated for engineering assistance to determine the cause of drift in these and other pressure sensors
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- of concern, and to recommend corrective ' solutions.
l Failure Data:
Manufacturer data pertinent to these switches are.as follows:
i Meletron Corp. (subsidiary of Barksdale) l Los Angeles, California l
Pressure Actuated Switch Model 372 Catalog'#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
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