ML20084C545

AO 50-219/74-49:on 740927,main Steam Line Low Pressure Switch RE23A Found to Trip at Pressure Less than Min of 860 Psig.Caused by Switch Repeatability.Ge Supplied Info to Reduce Setpoint

ML20084C545
Person / Time
Site:	Oyster Creek
Issue date:	10/04/1974
From:	Ross D JERSEY CENTRAL POWER & LIGHT CO.
To:	Giambusso A US ATOMIC ENERGY COMMISSION (AEC)
References
AO-50-219-74-49, NUDOCS 8304080098
Download: ML20084C545 (4)

Text

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. U U Jersey Central Power & Lig7t Company b1 D MADISON AVENUE AT PUNCH BOWL ROAD e MORRISTOWN, N.J. 07960

• 201-539-6111

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General (('j, Public Utilities Corporation SYSTEM October 4, 1974 g fc #^

Mr. A. Giambusso Deputy Director for Reactor Projects " h,,A j b'C Directorate of Licensing 1 g United States Atomic Energy Commission Washington, D. C. 20545 '4 j rv h

Subject:

Oyster Creek Station Docket No. 50-219 Abnomal Occurrence Report No. 50-219/74-49 The purpose of this letter is to forward to you the attached Abnormal Occurrence Report in compliance with paragraph 6.6.2.a of the Technical Specifi-cations.

Enclosed are forty copies of this submittal.

Very truly yours, Donald A. Ross f

Manager, Nuc1 car Generating Stations cs .

Enclosures cc: Mr. J. P. O'Reilly, Director Directorate of Regulatory Operations, Region 1

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8304080098 741004

PDR S~

ADOCK 05000219 /

PDR COPY S1Wf REGION -

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.ersey Central Power & Lig1t Company T l MADISON AVENUE AT PUNCH BOW 1. ROAD

• MORRISTOWN, N.J. 07960

• 201 539-6111 General

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Public Utihties Corporation i OYSTER CREEK NUCLEAR GENERATING STATION FORKED RIVER, NEW JERSEY 08731 Abnormal Occurrence Report No. 50-219/74-49 Report Date October 4, 1974 a

Occurrence Date September 27, 1974 Identification of Occurrence

}' Violation of the Technical Specifications, paragraph 2.3.7, main steam line low pressure switch RE23A 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 at steady state power with major parameters as follows:

j Power: Reactor, 998 MWt Electric, 300 MWe Flow: Recirculation, 20.2 x 10 6 lb/hr Feedwater, 3.4 x 10 6 lb/hr Reactor Pressure: 1020 psig Stack Gas: 9,850 pCi/sec Description of Occurrence On Friday, September 27,1974, at 1325, while performing a routine surveillance test on the four main steam line low pressure switches, it was discovered that switch RE23A tripped at 855 psig. This value is below the minimum required trip point of 860 psig which is derived by adding to the Technical Specification limit of 850 psig, a 10 psig head correction factor.

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! Abnormal Occurrence Report No. 50-219/74-49 Page 2 l I The "as found" and "as left" switch settings were:

"As Found" Settings "_As Left" Settings  ;

j RE23A 855 psig 860 psig  !

i RE23B 860 psig 860 psig .

RE23C 860 psig 860 psig I RE23D 860 psig 860 psig i 4

gparent Cause of Occurrence j l The cause of this occurrence is the recognized problem of switch repeatability. l t

Analysis of Occurrence ,

As indicated in the bases of the Technical Specifications, "The Icw pressure f isolation of the Main Steam Lines at 850 psig was provided to give protection against fast reactor depressurization and the resultant rapid cooldown of the ,

vessel. Advantage was taken of the scram feature which occurs when the Main l Steam Isolation Valves are closed to provide for reactor shutdown so that high power operation at low reactor pressure does not occur, thus providing protec-tion for the fuel cladding integrity safety limit."

The adverse consequences of reactor isolation occurring at reactor pressure approximately 5 psig below the specified minimum value 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 1 354 MWt with less than 10*6 recirculation flow. Therefore, the consequences of .

a 5 psig lower than normal reactor isolation and scram set point has no threatening l cffect whatsoever on the fuct cladding integrity.  :

The effects of a too rapid cooldown due to the lower isolation pressure are inconsequential since there is less than 1*F difference between the saturation temperature for 850 psig and 845 psig.  ;

Corrective Action Steam line pressure variations during daily stop valve testing make it impractical to include in the switc' set point the normal trip point variations to provide a sufficient margin abo o the Technical Specification limit. l The General Electric Company has furnished information on the feasibility of reducing the 850 psig set point to a lower value. This information is presently .

being evaluated by the Oyster Creek Nuclear Station's staff, and a Technical  !

Specification Change Request may be submitted as a result of this evaluation. "

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< Abnormal Occurrence Report No. 50-219/74-49 Page 3 '

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i l Failure Data i

Manufacturer data pertinent to these switches are as follows:

Meletron Corporation (subsidiary of Barksdale)

Los Angeles, California Pressure Actuated Switch '

Model 372 3

Catalog #372-6SS49A-293 i Range 20-1400 psig Proof Psi 1750 G Previous abnormal occurrence reports involving these switches are:  ;

1. Letter to Mr. A. Giambusso from 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 l 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 I

8. Abnormal Occurrence Report No. 50-219/74-37

9. Abnormal Occurrence Report No. 50-219/74-41

10. Abnormal Occurrence Report No. 50-219/74-42 i 11 Abnormal Occurrence Report No. 50-219/74-43 i

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