ML16340A715
| ML16340A715 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 11/30/1979 |
| From: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| To: | Crane P PACIFIC GAS & ELECTRIC CO. |
| References | |
| NUDOCS 7912190121 | |
| Download: ML16340A715 (8) | |
Text
gp,W AEG(gC'Ip0 4~*~4 UNITED STATES NUCLEAR REGULATORY COMMISSION REGION V 1990 N. CALIFORNIABOULEVARD SUITE 202, WALNUTCREEK PLAZA WALNUTCREEK, CALIFORNIA94596 November 30, 1979 Docket I'Ios. 50-275 50-323 Pacific Gas and EIectric Company 77 Beale Street San Francisco, California 94106 Attention:
tlr. Philip A. Crane, Jr, Assistant General Counsel Gentlemen:
The enclosed IE Bulletin No. 79-27 is forwarded for action.
A written response is required.
If you desire additional information regarding this matter, please contact this office.
W Sincerely, R.
H. Engelken Director
Enclosures:
l.
IE Bulletin Ho. 79-27 2.
Recently Issued IE Bulletins cc w/enclosures:
J. Worthington, PG&E W. Raymond, PG&E R.
- Ramsay, PG&E, Diablo Canyon
UNITED STATES SSINS No.:
6820 NUCLEAR REGULATORY CO!1!EMISSION Accession No.:
OFFICE OF INSPECTION AHD ENFORCE!1EHT 7910250499 WASHINGTON, D.C.
20555 November 30, 1979 IE Bulletin Ho. 79-27 LASS OF HQN-CLASS-1-E I>INSTRUMENTATION AND CONTROL PO'!FR SYSTE>l BUS DURING OPERATION Description of Circumstances:
An flovember 10,
- 1979, an event occurred at the Oconee Power Station, Unit 3, that resulted in loss o
oower to a non-class-1-E 120 'lac sinole phase power panel that sunplied power to the Integrated Control System (ICS) and the Non-Nuclear Instrumentation (HNI) System.
This loss of power resulted in control system malfunctions and significant loss of information tn the control room operator.
Specifically, at 3: 16 p.m., with L'nit 3 at 100 oercent power, the main condensate pumps tripned, aoparently as a result of a technician oerforming maintenance on the hotwell level control system.
This led to reduced feedwater flow to the steam generators, which resulted in a reactor trip due to high coolant system pressure and simultaneous turbine trip at 3:16:57 p.m.
At 3: 17: 15 p.m., the non-class-1-E inverter oower supply feeding all povIer to the integrated control system (which provides proper coordination of the reactor, steam qenerator feed>>ater control, and turbine) and to one NNI channel tripped and failed to automatically transfer its loads from the DC power source to the regulated AC power source.'he inverter tripoed due to blown fuses.
Loss of power to the NNI rendered control room indicators and recorders for the reactor coolant system (except for one wide-range RCS pressure recorder) and most of the secondary plant systems inoperable, causina loss of indication for systems used for decay heat removal and water addition to the reactor vessel and steam generators.
Upon loss of oower, all valves controlled by the ICS assumed their respective failure positions.
The loss of oower existed for anproximately three minutes, until an operator could reach the equipment room and manually switch the inverter to the regulated AC source.
The above event was discussed in IE Information Notice Ho. 79-29, issued November 16, 1979.
NUREG 0600 "Investiqation into the l'!arc."I 28, 1979 T!4[ Accident" also c'iscusses THI LER 78-021-03L whereby the PCS depressurized and Safety Injection occured on loss of a vital bus due to inverter failure.
Actions to He Taken by Licensees For all power reactor facilities with an operating license and fnr those nearing completion of construction (North Anna 2, Riablo Canyon, !<cGuire, Salem 2,
- Senuoyah, and Zimmer):
9 IE Bulletin Ho.
79-27 Hovember, 30, 1979'age 2 of 2 r
1.
Review the class-1-E and non-class 1-E buses supplying power to safety and non-safety related instrumentation and control systems which could affect the ability to achieve a cold shutdown condition using existing procedures or procedures developed under item 2 below.
For each bus:
a) b)
c) identify and review the alarm and/or indication provided in the control room to alert the operator to the loss of power to the bus.
identify the instrument and control system loads connected to the bus and evaluate the effects of loss of power to these loads including the ability to achieve a cold shutdown condition.
describe any proposed design modifications resulting from these reviews and evaluations, and your proposed schedule for implementing those modifications.
2.
Prepare emergency procedures or review existing ones that will be used by control room operators, including procedures required to achieve a cold shutdown condition, upon loss of power to each class 1-E and non-class 1-E bus supplying power to safety and non-safety related instrument and control systems.
The emergency procedures should include:
a) the diagnostics/alarms/indicators/symptom resulting from the review and evaluation conducted per item 1 above.
b) the use of alternate indication and/or control circuits which may be powered from other non-class 1-E or class 1-E instrumentation and control buses.
c) methods for restoring power to the bus.
Describe any. proposed design modification or administrative controls to be implemented resulting from these procedures, and your proposed schedule for implementing the changes.
3.
Re-review IE Circular Ho. 79-02, Failure of 120 Volt Vital AC Power Supplies, dated January 11,
- 1979, to include both class 1-E and non-class 1-E safety related power supply inverters".
Based on a review of operating experience and your re-review of IE Circular Ho. 79-02, describe any proposed design modifications or administrative controls to be implemented as a result of the re-review.
4.
Within 90 days of the date of this Bulletin, complete the review and evaluation required by this Bulletin and provide a written response describing your reviews and actions taken in response to each item.
Reports should be submitted to the Director of the appropriate HRC Regional Office and a copy should be forwarded to the HRC Office of Inspection and Enforcement, Division of Reactor Operations Inspection, Washington, D.C.
20555.
If you desire additional information regarding this matter, please contact the IE Regional Office.
Approved by GAO B180225 (R0072); clearance expires 7/31/80.
Approval was given
'under a blanket clearance specifically for identified generic problems.
-IE Bulletin No. 79-27 Novebmer 30, 1979 RECENTLY ISSUED I E BULLETINS Enclosure Bulletin ho.
Subject Date Issued Issued To 79 Boron Loss From BMR Control Blades 11/20/79 All B'lR onwer reactor facilities with an 79-25 Failures o
Vestinghouse 11/2/79 BFO Relays In Safety-Related Systems All nower reactor facilities with an OL or CP 79-17 (Pev.
1) 79-24 79-23 Pipe Cracks In Stagnant Borated Hater System At PMR Plants Frozen Lines Potential Failure of Emergency Diesel Generator Field Exciter Transformer 10/29/79 9/27/79 9/12/79 All PVR's with an OL and for information to other nower reactors All power reactor facilities which have either OLs or CPs and are in the late stage o
construction All Power Reactor Facilities with an Operatina License or a construction permit 79-14 Seismic Analyses for 9/7/79 (Suoplement 2)
As-Built Safety-Related Pi oi ng Systems All ~ower Reactor Facilities with an OL or a CP 79-22 Possible Leakaqe of Tubes 9/5/79 of Tritium Gas in Time-pieces for Luminosity To Fach Licensee who Peceives Tubes of Tritium Gas Used in Timepieces for Luminosity 79-13 Crackinq in Feedwater (Pev.
1)
System Piping 79-02 Pipe Support Base Plate (Rev.
1)
Desiqns Usina Concrete (Suoplement 1)
Exoansion Anchor Bolts 79-14 Seismic Analyses For (Suoplement)
As-Built Safety-Related Piping Systems 8/30/79 8/20/79 8/15/79 All Desiqnated Apnlicants for OLs All oower Reactor Facilities ivith an OL or a CP All Power Reactor Facilities with an OL or a CP