ML18136A304
| ML18136A304 | |
| Person / Time | |
|---|---|
| Site: | Surry, North Anna  |
| Issue date: | 11/30/1979 |
| From: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | Proffitt W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| References | |
| NUDOCS 7912190492 | |
| Download: ML18136A304 (6) | |
Text
- 11:
<ft UNITED STATES
~,
NUCLEAR REGULATORY COMMISSION REGION II
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101 MARIETTA ST., N.W., SUITE 3100 ATLANTA, GEORGIA 30303 In Reply Refer To:
l{Il:JPO 50-338, 50-339
~280, 50~:m_::,
Virginia Electric and Power Company Attn:
W. L. Proffitt Senior Vice President, Power P. 0. Box 26666
- Richmond, Virginia Gentlemen:
23261 I
NOV 3 o..'1979 The enclosed IE ~ulietin No. 79-27, is forwarded for action.
A written response is required. If you 1desire additional information regarding this matterr please contact this office.
Enclosures:
- 1.
- 2.
List of Recently'Issued IE Bulletins Sincerely,
*-**--*---~- \\';
'~~y James P. O'Reilly
- Director
_j
Virginia Electric and Power Company cc w/encl:
/
I -*
W.R. Cartwright, Station Manager Post Office Box* 402 Mineral, Virginia 23117 P~ G. Perry Senior Resident Engineer Post Office Box 38 Mineral, -Virgi~ia 23117 W..1L. Stewart, Manager Post Office Box 315 Surry, Virginia 23883
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NOV 3 0 1979. '
\\
I
I I
UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.G.
20555 November 30, 1979 SSINS No. :
6820 Accession No.:
7910250499 IE Bulletin No. 79 LOSS OF NON-CLASS IE INSTRUMENTATIQN AND CONTROL POWER SYSTEM BUS DURING OPERATION Description of Circumstances:
On November IO, 1979, an* event occurred at the Oconee Power Station, Unit 3, that resulted in loss of power to a non-class IE 120 Vac single phase power panel that supplied power to the Integrated Control System (ICS) and the Non-Nuclear Instrumentation (NNI) System.
This loss of power resulted in control system malfunctions and significant loss of information to the control room operator.
Specifica'ily, at 3:16 p.m., with Unit 3 at 100 percent power, the main condensate pumps tripped, apparently as a result of a technician performing 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 IE inverter power supply feeding all power to the integrated control sys-tern (which provides proper coordination of the reactor, steam generator feedwater 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.
The inverter tripped 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, causing loss of.indication for systems used.for decay heat removal and water addition to the reactor vessel and steam genera to-rs.
Upon loss of power, all valves controlled by the' !CS assumed 1:heir respective failure positions.
The loss of power existed for approximately three minutes, until an operator could reach the equipment room and manually switch the inverter to the regulated AC source.
I The above event was discussed in IE Information Notice No. 79-29, issued November 16, 1979.
NUREG 0_600 "Investigation into the' March 28, 1979 TMI Accident" also discusses TMI LER 78-021-031 whereby the RCS depr.essurized and Safe}y 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,operating license and for those nearing completion of construction (North Anna.2, Diablo Canyon, McGuire, Salem 2, Sequoyah, and Zimmer):
IE Bulletin No. 79-27 November 30, 1979 Page /2_ of, 3
- 1.
Review the class lE and non-class lE 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 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 lE and non-class lE 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 fr,om 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 lE or class lE 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 No. 79-02, Failure of 120 Volt Vital AC Power Supplies, dated January 11, 1979, to include both class lE and non-class lE safety-related power supply inverters.
Based on 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 r~quired 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 Off ice.
L e
IE Bulletin No. 79-27 November 30, 1979 Page 3 of 3 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*3o, 1979 41 Bulletin No.
79-27 79-26 79-25 79-17 (Rev. 1) 79-24 79-23
- RECENTLY ISSUED IE BULLETINS Subject Date Issued Loss of Non-Class lE 11/30/79 Instrumentation and Control Power System Bus During Operation Boron Loss From BWR 11/20/79 Control Blades Failures,of Westinghouse 11/2/79 BFD Relays In Safety-Related Systems Pipe Cracks In Stagnant 10/29/79 Borated Water System At PWR Plants
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Frozen Lines 9/27/79 Potential Failure of Emergency Diesel Generator Field Exciter Transformer 9/12/79 79~14 Seismic Analyses For 9/7/79 (Supplement 2) As-Built Safety-Related Piping Systems 79-22 79-13 (Rev. 1)
Possible Leakage of Tubes of Tritium Gas' in Time-pieces for Luminosity Cracking in Feedwater
.System Piping*
79-02 Pipe.Support Base Plate (Rev. 1)
Designs Using Concrete (Supplement 1) Expansion Anchor Bolts 79-14 (Supplement)
Seismic Analyses For As-Built Safety-.Related Piping Systems
, 9/5/79 8/30/79 8/20/79 8/15/79 Enclosure Issued To All-power reactor facilities which have either OLs or CPs and are in.:the late stage of construction.
All BWR power reactor facilities with an 01 All power reactor facilities with an OL' or CP All PWR's with an OL and for information to.other power reactors All power reactor facilities which have either OLs or CPs and are in the late stage of construction All Power Reactor Facilities with an Operating License or a construction permit All Power Reactor Facilities with an OL or a CP To Each Licensee who Receives Tubes of Tritium Gas Used in Timepieces for Luminosity All Designated Applicants for OLs All power Reactor Facilities with an OL or a CP All Power Reactor*