PNO-V-83-018, on 830421,util Received Ltr from C-E Informing of Error in Equivalent Voltages Corresponding to Setpoints Associated W/Steam Generator High Delta Pressure Trip Function.Corrective Action Being Developed

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PNO-V-83-018:on 830421,util Received Ltr from C-E Informing of Error in Equivalent Voltages Corresponding to Setpoints Associated W/Steam Generator High Delta Pressure Trip Function.Corrective Action Being Developed
ML20204F601
Person / Time
Site: San Onofre  Southern California Edison icon.png
Issue date: 04/25/1983
From: Bishop T
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
To:
References
PNO-V-83-018, PNO-V-83-18, NUDOCS 8305020183
Download: ML20204F601 (1)


PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE--PNO-V-83-18 Date: 4/25/8 D This preliminary notification constitutes EARLY notice of events of POSSIBLE safety or p l' c interest significance. The information is as initially received without verification or evaluation and is basically all that is known by IE staff on this date.

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FACILITY: Southern California Edison Company San Onofre Nuclear Generating Station Units 2 & 3 Notification of Unui:ual Event San Clemente, California Docket Nos. 50-361 and 50-362 Alert Site Area Emergency

SUBJECT:

STEAM GENERATOR DELTA PRESSURE SETPOINT General Emergency x Not Applicable On April 21, 1983, Southern California Edison Company (SCE) received a letter from Combustion Engineering (CE) informing them of an error in the equivalent voltages corresponding to setpoints associated with the steam generator high delta pressure trip function for Units 2 and 3. The equivalent voltage for the 50 psid trip setpoint was specified by CE as one volt higher than the correct value in a document from CE to SCE dated November 9,1981.

This one volt increase causes the setpoint to be 300 psid higher than assumed in the safety analysis.

The system compares the pressures in the secondary side of the two steam generators to identify a ruptured steam generator. The safety action upon rupture identification is to stop emergency feedwater to the ruptured steam generator. The higher than specified setpoint could result in a ruptured steam generator not being identified during a steam line break. If the ruptured steam generator is not identified, emergency feedwater would be provided to it on a low level signal. The continuation of feedwater to a ruptured steam generator has the potential for releasing excess steam which would pressurize the containment and also has the potential to increase cooldown of the primary. 'Jnits 2 and 3 are both in Mode 5.

l Licensee corrective action is being developed. RV will monitor the corrective action and will determine the generic applicability of the problem.

Media interest is not expected. Neither the licensee nor the NRC plans to issue a news release. Region V (San Francisco) received notification of this occurrence from the resident inspector at 9:00 a.m. on April 22. 1983. This information is current as of 8:00 a.m.

on April 25, 1983.

CONTACT: T. W. Bishop FTS 463-3751

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