ML19256F439
| ML19256F439 | |
| Person / Time | |
|---|---|
| Site: | Humboldt Bay |
| 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 7912190143 | |
| Download: ML19256F439 (1) | |
Text
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UNITED STATES gb-
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NUCLEAR REGULATORY COMMISSION
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1990 N. CALIFORNI A BOULEVARD
,e SulTE 202, WALNUT CREEK PLAZA N/
,,a WALNUT CR EE K. CALIFORNI A 9459G November 30, 1979 Docket No. 50-133 Pacific Gas and Electric Company 77 Beale Street San Francisco, California 94106.
Attention: fir. 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.
Sincerely,
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R. H. Engelken Director
Enclosures:
1.
Recently Issued IE Bulletins cc w/ enclosures:
W. Barr, PG&E W. Raymond, PG&E E. Weeks, PG&E, Humboldt Bay
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t UNITED STATES SSINS No.: 6820 fiUCLEAR REGULATORY C0",'11SS10f!
Accession f'o. :
OFFICE OF INSPECTION AND ENFORCE"ENT 7910250499 UASHINGTON, D.C.
20555 flovember 31, 1979 IE Bulletin f!o. 79-27 LOSS OF NON-CLASS-1-F INSTP.UMENTATION AND CONTROL on'.!ER 9YSTEM BUS DURING OPERATION Descrintion of Circumstances:
On flovenber 10, 1979, an event occurred at the Oconee Power Station, Unit 3, that resulted in loss of cower to a non-class-1 F 120 Vac sinale phase onwer panel that suoplied oower to the Inteorated Control Systen (ICS) and the f!on-Nuclear InstruFantation (f!NI) Systen. This loss of ' cower resulted in control system nalfur.ctions and signi'ficant loss of information to the control room operator.
Specifically, at 3:16 o.m., with Unit 3 at 100 cercent power, the rain condensate pumps tripned, aoparently as a result of a technician oerfoming naintenance on the hotwell level control system. This led to reduced feedwater flow to the stean generators, which resulted in a reactor trip due to hiah coolant system pressure and sinultaneous turbire trip at 3:16:57 o.m.
At 3:17:15 p.m., the non-class-1-E inverter power supply feeding all cower to the integrated control systen (which provides procer coordination of the reactor, stean ge.arator feedwater control, and turbine) and to one NNI channel Diooed and failed to automatically transfer its loads from the DC power sour:.e to the regulated AC power source. The inverter trioced due to blown fuses.
Loss of power to the f.'ill rendered control room indicators and recorders for the reactor coolant systen (except for one wide-rance RCS pressure recorder) and nost of the secondary olant systens inoperable, causina loss of indication for systens used for decay heat renoval and water addition to the reactor vessel and stean generators. Upon loss of oower, all valves controlled by the ICS assured their resoective failure positions.
The loss of oower existed for anproximately three ninutos, until an onerator could reach the eauionent roon and manually switch the inverter to the regulated AC source.
The above event was discussed in IE Infornation Notice No. 79-29, issued flovember 16, 1979.
NUREG 0600 "Investication into the Parch 28, 1979 TMI fccident" also discusses Tf1I LER 78-021-03L whereby the RCS denressurized and Safety Injection occured on loss of a vital bus due to inverter failure.
Actions to Be Taken by Licensees For all power reactor facilities with an coerating license and for those.nearinq completion of construction (North Anna 2, Gia,blo Canyon, 'icquire, Salem 2,-
Seouoyah, and Zinner):
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IE Bulletin No. 79-27 ti m mber 30, 1979 Page 2 of 2
' '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) identify and review the alarm and/or indication provided in the control room to alert.he operator to the loss of power to the bus.
b) 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.
c) describe any proposed design modifications resulting from these reviews and evaluations, and your proposed schedule for implementing those modi fica tions.
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 /symptcm 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 fron other non-class 1-E or class 1-E instrumentation and control bures.
c) methods for restoring power to the bus.
Describe any oroposed design modification or administrative controls to be implemented rdalting from these procedures, and your proposed schedule for implementing the changes.
3.
Re-review IE Circular No. 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 oh a review of operating experience and your re-review of IE Circular No. 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 NRC Regional Office and a copy should be forwarded to the NRC 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 GA0 Bl80225 (R0072); clearance expires 7/31/80.
Approval'wa's given under a blanket clearance specifically for identified generic problems.
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IE. Bulletin flo. 79-27 Enclosure Movebner 30, 1979 RECENTLY ISSUED IE BULLETINS Bulletin Subject Date Issued Issued To No.
79-26 poron Loss Fron RUR 11/20/79 All BNP cower reactor Control Blades facilities with an DL 79-25 Failures of Vestinchouse 11/2/79 All nower reactor EF0 Relays In Safety ? elated facilities with an Systens OL or CP 79-17 Pipe Cracks In Stacnant 10/29/79 All PWR's with an (Rev. 1)
Borated Water Systen At OL and for information PWR Plants to other oower reactors 79-24 Frozin Lines 9/27/79 All power reactor facilities which have either OLs or cps and are in the late stage of construction 79-23 Potential Failure of 9/12/79 All Power Reactor Energency Diesel Facilities with an Generator Field Operatina License or Exciter Transforner a construction permit 79-14 Seisnic Analyses For 9/7/70 All Power Reactor (Suoplement2)
As-Built Safety-Related Facilities with an Pioing Systens OL or a CP 79-22 Possible Leakaqe of Tubes 9/5/79 To Fach Licensee of Tritium Gas in Time-who Receives Tubes pieces for Luminosity of Tritiun Gas Used in Tinaoieces for Luninosity 79-13 Crackinq in Feedwater 8/30/79 All Desiqnated (Rev. 1)
Systen Pining Aonlicants for OLs 79-02 Pipe Sunport Base Plate 8/20/79 All nower Reactor (Rev. 1)
Designs Usina Concrete Facilities with an (Sucolenent 1)
Exoansion Anchor Bolts OL or a CP 79-14 Seisnic Analyses For 8/15/79 All Power Reactor (Suoplement) As-Built Safety-Related Facilities with Pipinq Systens an OL or a CP
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