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Jersey Centra Power & Lig7t Company MADISON AVENUE AT PUNCH COWL ROAD
- MORRtSTOWN, N.J. 07960
- 201-539-6111 esnanw rus General {a Public Utilities Corporation sysrsn
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March 22, 1974 sY i
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Mr. A. Giambusso g
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N Deputy Director for Reactor Projects g
Directorate of Licensing i
United States Atomic Energy Commission Washington, D. C. 20545
Dear Mr. Giambusso:
Subject:
Oyster Creek Station Docket No. 50-219 Abnormal Occurrence Report No. 50-219/74/22
'Ihe purpose of this letter is to fozward to you the attached Abnormal Occurrence Report in compliance with paragraph 6.6.2.a of the Technical Specifications.
Enclosed are forty copies of this submittal.
Very truly yours, Donald A. Ress Manager, Nuclear Generating Stations cs Enclosures cc: Mr. J. P. O'Reilly, Director Directorate of Regulatory Operations, Region I 3
2006 9604170229 960213 PDR FOIA A/
DEKOK95-258 PDR V-
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OYSTER CREEK NUCLEAR GENERATING STATION FORKED RIVER, NEW JERSEY 08731 i
Abnomal Occurrence Report No. 50-219/74/22 Report Date-March 22, 1974' Occurrence Date March 15,1974-Identification of Occurrence Violation of the Technical Specifications, paragraph 2.3.7, low pressure main steam line pressure switch RE23D was found to trip at a pressure less than the minimum required value of 860 psig.
This event is considered to be an abnormal' occurrence as 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 of the. event were as follows:
Power:
Reactor,1902 Mit Electric, 661 Mh'e 4
Flow:
Recirculation, 15.3 x 10 gpm 6
Feedwater, 7.10 x 10 lb/hr Reactor Pressure:
1020 psig Stack Gas:
40,600 pCi/sec Description of Occurrence On Friday, March 15,1974, at 1550, while perfoming a routine surveillance test on the four main steam line low pressure switches, it was discovered that
'RE23D tripped.at 850 psig. His value is below the minimum r6 quired trip point-of 860 psig which is derived by adding to the Technical Specification limit of 850 psig a 10 psig head correctic,n factor, he "as found" and "as left" switch settings were:
"As Found" Settings "As Left" Settings RE23A 865 psig 861 psig RE23B 864 psig 864 psig
' RE23C 865 psig 865 psig RE23D 850,psig 860 psig 4
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i Abnormal Occurrence No. 50-219/74/22 Page 2-
- Pressure switch RE23D was immediately recalibrated and rechecked to actuate at 860 psig.
. Apparent Cause of Occurrence
. Design is considered to be a major factor contributing to this ' event.
Switch
. repeatability is a recognized problem and work is in progress to formulate a final solution.
Analysis of Occurrence As indicated in the bases of the Technical Specifications, "The low pressure
. isolation of the Main Steam Lines at 850 psig was provided to give protection against fast reactor depressurization and the resultant rapid cool-down of the vessel.
Advantage was taken of the scram feature which occurs 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 10 psig below the specified minimum value of 860 psig is limited to those. effects attendant to a greater than normal reactor cool-down 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 MWt with less than 10% recirculation flow. Therefore, the consequences of a 10 psig lower than normal reactor isolation and scram set point has no threatening effect whatsoever on the fuel cladding integrity.
He effects of a too rapid cool-down due to the lower isolation pressure are inconsequential since there is less than 2*F difference between the saturation temperature for 860 psig and 850 psig.
Corrective Action l
Continuing corrective actions being 'taken at this time are as follows:
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Investigation is being conducted into the basis for the steam line low pressure setting of 850 psig.
Development of a Technical Specification change to lower the set point will follow if results of transient. analyses indicate this possibility.
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Recommendations to possibly reduce or eliminate the sensor set point change problem have been received.
It was reported that General Electric tests on a pulsating line to simulate plant conditions show that pre-cycled Barksdale switches show improvement but that the switches still do not meet 1% repeatability.
General Electric, therefore, recommended e
an Ashcroft switch as it is more accurate.
D e Ashcroft catalog ntunber is 61 S 6080 BN20-06L-1028.
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Abnormal Occurrence No. 50-219/74/22 Page 3 As a result, one switch of. each type (pre-cycled Barksdale and Ashcroft) has been purchased for test and evaluation at Oyster Creek.
An Ashcroft switch is currently on hand and undergoing evaluation.
Failure Data 4
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.
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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 f
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