ML19256F445
| ML19256F445 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 11/30/1979 |
| From: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| To: | Mattimoe J SACRAMENTO MUNICIPAL UTILITY DISTRICT |
| References | |
| NUDOCS 7912190151 | |
| Download: ML19256F445 (1) | |
Text
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UNITED STATES 1.h *d)(,g y f s,.,q{
NUCLEAR REGULATORY COMMISSION i
REGION V o, ~-[rh' I 8
1990 N. CALIFORNIA BOULEVARO
,e SulTE 202. WALNUT CREEK PLAZA WALNUT CREE K, CALIFORi" A 94596 fiovember 30, 1979 Docket :10. 50-312 Sacramento Municipal Utility District P. O. Box 15830 Sacramento, California 95813 Attention: Mr. John J. Mattimoe Assistant General Manager Gentlemen:
The enclosed IE Bulletin flo. 79-27 is forwarded for action. A written response is required.
If you desire additional information regarding this matter, please contact this office.
Sincerely, o
nb-R. H. Engelken Director
Enclosures:
1.
IE Bulletin ilo. 79-27 2.
Recently Issued IE Bulletins cc w/ enclosures:
R. J. Rodriguez, SMUD L. G. Schwieger, SMUD
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UtlITED STATES SS!NS No.: 6820 NUCLEAR REGULATORY COPMISSIO" Accessior. Mc.:
OFFICE OF INSPECTION AND ENFORCE"ENT 7910250499 UASHIIGTCN, D.C.
20555 flovember 30, 1979 IE Bullatin ?!o. 79-27 LMS OF t!O!1-CLASS-1 r INSTRUMENTATICN AND CONTROL on"FR <Y<Tc" BUS DURING ODERAT!0fl Descrintion of Circumstances:
on ?!cverber 10, 1979, an event occurred at the Oconee Pcwer Station, Unit 3, that resulted in loss of oower to a non-class-1 r 120 Vac sincle chase oower canel that sunolied oower to the Intearated Control Systen (ICC) and the r!on-Nuclear Instrurentation (f!flI) Systen. This loss o' cower resulted in control system ralfunctions and significant loss of information to the control rocn operator.
Soecifically, at 3:16 o.n., with Unit 3 at ICO cercent cower, the rain condensate pum::s trinned, aoparentiv as a result of a technician cerforming raintenance on the hotwell level control systen. This led to reduced feedwater flow to the stean qenerators, which resulted in a reactor trio due to hiah coolant system pressure and sinultaneous turbine trio at 3:16:57 o.n.
At 3:17:15 c.r., the non-class-1-E inverter oower sucoly feeW.nq all cower to the integrated control syster (which provides procer coordinatOm of the reactor, stean generator feedwater control, and turbine) and to one Nfil channel tricoed and failed to autoratically transfer its loads from the DC power source to the regulated AC cower source. The inverter tricoed due h blown fuses. Loss of power to the NNI rendered control rocn indicators and recorders for the reactor coolant systen (exceot for one wide-rance RCS oressure recorder) and rost of the secondary olant systers inoperable, causino loss of indication for systens used for decay heat reroval and water addition to the reactor vessel and stean generators. Uoon loss of oower, all valves controlled by the ICS assured their resoective failure posi tions. The loss of oower existed for anoroxinately three ninutes, until an ooerator could reach the eauicnent roon and rant 'ly switch the inverter to the regulated AC source.
The above event was discussed in IE Infornation !!otice No. 79-29, issued flove-ber 16, 1979.
NUDFG 0600 "Invectication into the March 28, 1979 m i fccident" also discusses T!1I LER 73-021-0?L whereby the RCS danressurized and Safety injection occured on loss of a vital bus due to inverter failure.
Actions to Be Taken by Licensees For all cower reactor facilities with an coeratina license and 'or those nearino coroletion of construction (florth Anna 2, Oiablo Canyon, 'icquire, Saler 2, Seouoyah, and Zirrer):
2
W IE Bulletin flo. 79-27 flovember 30, 1979 Page 2 of 2 1.
Review the class-1-E and non-cla',s 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 the 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 frca 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 roca operators, including proccdures requir?d to achieve a cold shutcown 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.
o) 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) nethods 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 lo. 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 flo. 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 f1RC Regional Office and a copy should be forwarded to the flRC 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 B180225 (R0072), clearance expires 7/31/80.
Approval was given uncer a blanket clearance specifically for identified generic problems.
f62[f68
IE Bulletin flo. 79-27 Enclosure Novebrer 30, 1979 RECENTLY ISSUED IE BULLETINS Bulletin Fubject Date Issued Issued To
'fo.
79-26 Doron Lnss Fren 9' R 11/20/74 all BND cower reactor Control Clades facilities with an rl 79-25 Failures of Pestinchouse 11/2/79 All onwer reactor BFG Delays In Fafety Delated facilities with an Systems OL or CP 79-17 Pir.e Cracks In Stacnant 10/29/79 All P'AD 's with an (Rev. 1)
Borated Water Systen At OL and #or information PWR Plants to other oower reactors 79-24 Frozen Lines 9/27/79 All power reactor facilities which have either OLs or cps and are in the late stace of construction 79-23 Potential Failure of 9/12/79 All Power Reacter Emergency Oiesel Facilities with an Generator Field Operatina License or Exciter Trans#omer a construction per it 79-14 Seismic Analyses For 9/7/79 All Dower Reactor (Sucolement2)
As-Built Safety Related Facilities with an Pioing Systems OL or a CD 79-22 Dossible Leakane of Tubes 9/5/79 To Each Licensee of Tritium Gas in Time-who Receives Tubes oieces for Luminosity of Tritium Gas Used in Timaoieces for Luninosity 79-13 Cracking in Feedwater 8/30/79 All Oesiqnated (Rev. 1)
Systen Pining Aonlicants for OLs 79-02 Pipe Suoport Base Plate 8/20/79 All newer Reactor (Rev. 1)
Desinns Usina Concrete Facilities with an (Sucolerent 1)
Exoansion Anchor Rolts OL or a CP 79-14 Seismic Analyses For 8/15/79 All Power Reactor (Sucolerent) As-9uilt Safety Delated Facilities with Dipina Systems an OL or a CP w
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