ML19347C807

AO 73-30:on 731206,main Steam Line Low Pressure Switches RE23A Through RE23D Tripped at Pressure Below Min Setpoint of 850 Psig.Cause Undetermined.Switches Reset.Mfg Conducting Study W/Ge to Investigate Setpoint Drift

ML19347C807
Person / Time
Site:	Oyster Creek
Issue date:	12/06/1973
From:	Sullivan J JERSEY CENTRAL POWER & LIGHT CO.
To:
References
AO-73-30, NUDOCS 8103040733
Download: ML19347C807 (3)

Text

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t Preliminary Abnormal Occurrence Report No. 73-30 -

SUBJECT:

Violation of the Technical Specifications, paragraph 2.3.7, Low Pressure Main Steam Line pressure switches were found to trip at a pressure greater than 850 psig.

This event is considered to be an abnormal occurrence as defined in the Technical Specifications, paragraph 1.15A. Notification of this event, as required by the Technical Specifications, para-graph 6.6.2a, was made to Mr. E. Greenman, AEC Region 1, Direc-

. torate of Regulatory Operations, on h'ednesday, December 12, 1973, during his visit to the plant, and by telecopier on Thuuday, December 13, 1973, at 1520 SITUATION: On Thursday, December 6,1973, while performing surveillance

. testirig on the four (4) Main Steam Line Low Pressure Switches, RE23A, B, C, and D, all four swit'ches were found to trip at pressures between 15 and 50 psig below the minimum required set-point of 850 psig. !!anufacturer data pertinent to the switches is as follows:

Meletron Corp. (subsidiary of Barksdale)

Los Angeles, California Pressure Actuated Switch -

MQdel 372 Catalog #372-6SS49A-293 Range 850 G Dec.

Proof Psi. 1750 G ,

The "as found" trip values were recorded as follows:

RE23A - 835 RE23B - 835 RE23C - 800 RE23D - 820 T/o Soh733 ,

s ,.

.Abn:rnal Occurrenca .

Report No. 73-30 Decembsr 6, 1973

. CAUSE: . At 'this time, the cause of this event has not been determined.

Plant personnel have contacted the manufacturer who ascertained that problers of setpoint drift with instruments of this type

- have been recogni:cd. Currently, the manufacturer is conducting E

a study with General Electric to investigate and resolve this drift problem. The results of this study are to be reported to the AEC by the manufacturer and General Electric.

REhEDIAL ACTION:

All four switches were reset to conform with the Technical Specification requirement of >850 psig. The calibration of the test device was re' checked and found to be accurate, substantiating that the switches, in fact, tripped at the indicated values.

SAFETY SIGNIFICANCE:

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 resulting rapid cooldown of the vessel. Advantage was taken of the scram feature which occ 2rs when the hbin Steam Line Isolation Valves are closed to providu 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 temperature difference for saturated steam at 850 psig and 800 psig is Icss than 8 F; thus, the resulting cooldown effect is considered to be negligibic.

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- hreliminary **

Abnormal Occurrcncs ( '

r Repart No. 73-30 -

Decembsr 6, 1973 h'ith regards to power operation below 850 psig and the atten-dant effects on the fuel cladding integrity safety limit, power level must be limited when pressure is less than 600 psig or flow is less than 10% to 354 mT or approximately 18.3'4 of rated.

As stated in the Technical Specifications, "This value is appli-cabic to ambient pressure and no flow conditions. For any greater pressure or flow conditions there is increased margin."

1he fuel cladding integrity safety limit curve has been developed and is applicable for pressure in excess of 600 psig. 'ihe refore ,

whether a reactor scrc.n occurs at 850 psig or 800 psig has little safety significaitee since no severe restrictions on critical heat flux are imposed until pressure is less than 600 psig.

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DIt9: 12/6/73

- *-  ! )ime: 1:30 p.m.

Preliminary Abnormal Occurrence Report No. 73-30

SUBJECT:

Violation of the Technical Specifications, paragraph 2.3.7, Low Pressure Main Steam Line pressure switches were found to trip at a pressure greater than 850 psig.

This event is considered to be an abnormal occurrence as defined-in the Technical Specifications, paragraph 1.15A. Notification of this event, as required by the Technical Specifications, para-graph 6.6.2a, was made to Mr. E. Greenman, AEC Region I, Direc-torate of Regulatory Operations, on Wednesday, December 12, 1973, during his visit to the plant, and by telecopier on Thursday, December 13, 1973, at 1520 SITUATig: On Thursday, December 6,1073, while performing surveillance testing on the four (4) Main Steam Line Low Pressure Switches, RE23A, B, C, and D, all four switches were found to trip at pressures between 15 and 50 psig below the minimum required set-point of 850 psig. Manufacturer data pertinent to the switches is as follows:

Meletron Corp. (subsidiary of Barksdale)

Los Angeles , California Pressure Actuated Switch Model 372 Catalog #372-6SS49A-293 Range 850 G Dec.

Proof Psi. 1750 G -

The "as found" trip values were recorded as follows:

RE23A - 835 RE23B - 835 RE23C - 800 RE23D - 820 f/b30 0753

..Prelitinsry ('

.Abnsrcal Occurrenc3' Report No. 73-30 Deccmber 6,1973

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CAUSE: At this time, the cause of this event has not been determined.

Plant personnel have contacted the manufacturer who ascertained that problens of setpoint drift with instruments of this type have been recognized. Currently, the manufacturer is conducting a study with General Electric to investigate and resolve this drift problem. The results of this study are to be reported to the AEC by the manufacturer and General Electric. .

REMEDIAL ACTION:

All four switches were reset to conform with the Technical i Specification requirement of >850 psig. The calibration of the test device was rechecked and found to be accurate, substantiating that the switches, in fact, tripped at the indicated values.

SAFETY SIGNIFICANCE:

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 resulting rapid cooldown of'the vessel. Advantage was taken of the scram feature which occurs when the hbin Steam Line ,

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 temperature difference for saturated steam at 850 psig and 800 psig is less than 8 F; thus, the resulting cooldown effect is considered to 'se negligible.

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.Prelicinnry Abnomal Occurrence -

Report No. 73-30 December 6,1973 With regards to power operation below 850 psig and the atten-

}, dant effects on the fuel cladding integrity safety limit, power level must be limited when pressure is less than 600 psig or flow is less than 10% to 354 MhT or approximately 18.3% of rated. -

As stated in the Technical Specifications, "This value is appli-cable to ambient pressure and no flow conditions. For any greater pressure or flow conditions there is increased margin."

He fuel cladding integrity safety limit curve has been developed

. and is applicable for pressure in excess of 600 psig. Herefore, whether a reactor.scra.n occurs at 850 psig or 800 psig has little '

safety significance since no severe restrictions on critical heat flux are imposed until pressure is less than 600 psig.

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I Prepared by: /> . Date: *O g 3 v~ y

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