ML19343C221

AO 50-219/74/42:on 740725,main Steam Line Low Pressure Switches RE23A,B,C & D Tripped at Pressures Less than Min Required Value of 860 Psig.Caused by Switch Repeatability. Setpoint Accuracy & Tolerance Under Investigation

ML19343C221
Person / Time
Site:	Oyster Creek
Issue date:	07/25/1974
From:	Manning J JERSEY CENTRAL POWER & LIGHT CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
References
AO-50-219-74-42, NUDOCS 8103040447
Download: ML19343C221 (4)

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,' - 5 : ial Telephone Date of 1.eport Date: 7/25/74 Occurrence: 7/25/74 Initial liritten Time of Report Date: 7/25 / 74 Occurrence: 1015 OYSTER CREEK NUCLEAR GENERATING STATION FORKED RIVER, NEW JERSEY 08731 Abnomal Occurrence Report No. 50-219/74/ 42 IDENTIFICATION Violation of the Technical Specifications, paragraph 2.3.7, OF OCCURRENCE:

Main Steam Line Low Pressure Switches RE23A, B, C, and D, found to trip at pressures less than the minimum required value of 860 psig.

'Ihis event is considered to be an abnonral occurrence as de-fined in the rechnical Specifications, paragraph 1.15A.

CONDITIONS PRIOR X Steady State Pcwer Routine Shutdown TO 0Cf.0ME4Cri: riot 5tr.ndby Operation Cold Shutdown Load Changes During Refueling Shutdown Routine Power Operation Routine Startup Other (Specify)

Operation Power: Reactor,1898 FMt Elec. , 653 FMe Flow: Recirc. ,15.8 X 104 gpm l

Feed., 7.05 X 106 lb/hr Reactor Pressure: 1020 psig Sta:h Car: 13,065 pCi/:cc DESCRIPTION OF On Thursday, July 2S,1974, at 1015, while performing a routine

! OCCURRENCE:

surveillance test on the four Main Steam Line Low Pressure Switches, it was discovered that switches RE23A, B, C, and D

tripped at 849, 854, 859, and 855 psig, respectively. These values are below the minimum required trip point of 360 pt;g which is derived by adding to the Technical Specification limit of 850 psig a 10 psig head correction factor.

P00R ORIGINAL 7,

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/mnormal Occurrenca

"..eport No. 50-219/74/42 Page 2

, The "as found" an.t "as left" switch settings were:

'As Found" Settings "As Left" Settings RE23A 849 psig 861 psig RE23B 854 psig 860 psig RE23C 859 psig 862 psig RE23D 855 psig 862 psig APPARENT CAUSE X Design Procedare OF OCCURRENCE: Manufacture _ Unusual Service Condition Installation / Inc. Environmental Construction Component Failure Operator Other (Specify)

The cause of this occurrence is switch repeatability, which is a recognized problem.

ANALYSIS OF OCCURRENCE:

As indicated in the bases of the Technical Specifications, "Re low pressure 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 Steam Isolation Valves are closed to provide for reactor shutdown so that high power operat!.cn at low reactor pressure does not occur, thus providing protec-tion for the fuel cladding integrity safety limit."

He adverse consequences of reactor isolation occurring at reactor pressure approxicately 11 psig below the specified minitram value of 860 psig is limited to those effects atten-dant to a greater than normal reactor cooldown rate. He fuel cladding integrity safety limit only comes into effect l

l P00R ORIGINAL

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Abnormal Occurrence Report No. 50-219/74/42 Page 3 for power operation at reactor pressures less than 600 psig or for power operation greater than 354 M.'t with less than 10's recirculation flow. Therefore, the consequences of a 11 psig lower than normal reactor isolation and scram set-point has no threatening effect whatsoever on ,the fuel cladding integrity.

The effects of a too rapid cooldown due to the lower isola-tion pressure are inconsequential since there is less than 20F difference between the saturation temperature for 850 psig and 839 psig.

CORRECTIVE Setpoint accuracy and tolerance in not only these instrument:

ACTION:

but in others as well is under investigation by Company and GPU personnel with General Electric Company.

FAILURE DATA: Manufacturer data pertinent to these switches are as follows:

Meletron Corp. (subsidiary of Barksdale)

Los Angeles, California Pressure Actuated Switch Model 372 Catalog #372-6S549A-293 Range 20-1400 psig Proof Psi. 1750 G Previous Abnormal Occurrence Reports involving these switches are:

1. Letter to Mr. A. Gianbusso from Mr. D. A. Ross, dated December 24, 1973. - .

2. Abnormal Occurrence Report No. 74-1.

3. Abnormal 0.currence Report No. 74-9.

P00R ORIGINAL

. s Abnomal Occurrence Page 4 R: port No. 50-219/74/42

4. Abnomal Occurrence Report No. 74-10. .

5. Abnomal Occurrence Report No. 74-12.

6. Abnomal Occurrence Report No. 74-22.

7. Abnomal Occurrence Report No. 74-35. i

8. Abnomal Occurrence Report No. 74-37.

9. Abnomal Occurrence Report No. 74-41.

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l Prepared by: _

. \ % ,' Date: 7/25/74 N

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P00R ORIGINAL

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