ML20084C803

AO 50-219/74-44:on 740809,main Steam Line Low Pressure Switches RE22A,B,C & D Found to Trip at Pressures Less than Min of 860 Psig.Caused by Switch Repeatability

ML20084C803
Person / Time
Site:	Oyster Creek
Issue date:	08/19/1974
From:	Ross D JERSEY CENTRAL POWER & LIGHT CO.
To:	Giambusso A US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20084C806	List: ML20084C803 ML20084C848
References
AO-50-219-74-44, NUDOCS 8304080231
Download: ML20084C803 (4)

Text

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l'l Jersey Central Power & Light Company " , i' s y -

MADISON AVENUE AT PUNCH BOWL ROAD

• MORRISTOWN, N. J. 07960

• 201-53D-6111 nFiWDE M OF T44.

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Pubhc Utilit.es Corporation __-_._ _ . .

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August 19, 1974

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"3 United States ? tonic Energy Conciission Washington, D. C. 20345 g' , ,/';

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Dear Mr. Gionbusso:

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Subject:

Oyster Creek Station Docket No. 50-219 isbnormal Occurrence Report No. 50-219/74-44 The purpose of this letter is to forward to you the attached Abnorreal Occarrence Report in compliance with paragraph 6.6.2.a of the Technicci Specifications.

Enclosed are forty copics of this subnittal.

Very truly yours,

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Donald A. Ross Manager, Nuclear Generating Stations es Enc 1csures cc: Mr. J. P. O'Reilly, Director Directorate of Regulatory Operations, Rcgion 1 1

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o o oo n[ &ll Jersey Central Power & Light Company ef hj MADISON AVENUE AT PUNCH BOWL ROAD

• MORRISTOWN, N.J. 07960

• 201-539-6111

.a . . or 1 a Generai [hjjj, Public Utihbes Corporation SVSTE hr OYSTER CREEK NUCLEAR GENERATING STATION FORKED RIVER, NEW JERSEY 08731 Abnormal Occurrence Report No. 50-219/74-44 Report Date August 19, 1974 Occurrence Date f

August 9, 1974 Identification of Occurrence Violation of the Technical Specifications, paragraph 2.3.7, main steam line low pressure switches RE23A, RE23B, RE23C, and RE23D were found to trip at pressures 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:

Power: Reactor, 1910 MWt Electric, 650 MWe Flow: Recirculation, 59.3 x 10 6 lb/hr Feedwater, 7.133 x 106 lb/hr Reactor Pressure: 1020 psig Stack Gas: 27,500 pCi/sec Description of Occurrence On Friday, August 9,1974, at 1000, while performing a routine surveillance test on the four main steam line low pressure switches, it was discovered that switches RE23A, RE23B, RE23C, and RE23D tripped at 850 psig, 855 psig, 850 psig, and S47 psig, respectively. These values are belew 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. 50-219/74-44 0 Page 2 i

i l The "as found" and "as left" switch settings were:

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) "As Found" Settings "As Left" Settings l RE23A 850 psig 863 psig I RE23B 855 psig 860 psig f RE23C 850 psig 860 psig i RE23D 847 psig 863 psig f

l Apparent Cause of Occurrence I

j The cause of this occurrence is switch repeatability.

I j Analysis of Occurrence l 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 depressuri::ation and the resultant rapid cooldown of the j 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 j power operation at low reactor pressure does not occur, thus providing protec-l tion for the fuel cladding integrity safety limit.

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} The adverse consequences of reactor isolation occurring at reactor pressure j approximately 13 psig below the specified minimum value of 850 psig is limited j 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 i at reactor pressures less than 600 psig or for power operation greater than j' 354 MWt with less than 10% recirculation flow. Therefore, the consequences of 1 a 13 psig lower than normal reactor isolation and scram set point has no threatening

) effect whatsoever on the fuel cladding integrity.

j The effects of a too rapid cooldown due to the lower isolation pressure are

! inconsequential since there is approximately a 2'F difference between the i saturation temperature for 850 psig and 837 psig.

J j Corrective Action 1

j Steam line pressure variations during daily stop valve testing make it impractical j to include in the switch set point the normal trip point variations needed to j provide a sufficient margin above the Technical Specification limit.

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Set point accuracy and tolerance in not only these instruments but in others j as well are under investigation by Jersey Central Power f, Light Company, i GPU Service Corporation, and General Elcetric Company.

1, hhile this investigation is being completed, the Plant Operations Review Committec

. has approved the use of in line sintered metal snubbers in the instrument sensing i lines to dampen the steam line pressure variations while still providing proper

! response to transient conditions. Elimination of this hydraulic noise will allow the set point of switches to be raised to allow increased margin above the Technical

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Specification limit. The Plant Operations Review Committee has transmitted-this

proposal to the General Office Review Board for final approval, i

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" : . Abnormal Occurrence, Report No. 50-219/74-44 Page 3 l

Manufacturer data pertinent to these switches are as follows:

( Meletron Corporation (subsidiary of Barksdale) l Los Angeles, California l Pressure Actuated Switch l Model 372 l 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 D. A. Ross, dated l December 24, 1973.

2. Abnormal Occurrence Report No. 50-219/74-1 l 3. Abnormal Occurrence Report No. 50-219/74-9 l

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

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

10. Abnormal Occurrence Report No. */4-219/74-42

11. Abnormal Occurrence Report No. 74-219/74-43 I

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