ML20004C934
| ML20004C934 | |
| Person / Time | |
|---|---|
| Site: | Trojan File:Portland General Electric icon.png |
| Issue date: | 05/21/1981 |
| From: | Sniezek J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE) |
| To: | |
| Shared Package | |
| ML20004C928 | List: |
| References | |
| DD-81-06, DD-81-6, NUDOCS 8106080055 | |
| Download: ML20004C934 (12) | |
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D0-81-6 llh UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT James H. Sniezek, Acting Director r
In the Matter of
)
)
Portland General Electric Company
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Docket No. 50-344 (Trojan Nuclear Plant Unit 1)
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DIRECTOR'S DECISION UNDER 10 CFR 2.206 By mailgram dated April 20, 1981, the Trojan Decommissioning Alliance requested that the U.S. Nuclear Regulatory Commission (NRC) order the immediate shutdown and launch an investigation of the Trojan Nuclear Plant of the Portland General Electric Company. This request has been considered under the provisions of 10 CFR 2.206 of the Commission's regulations.
The request by the Alliance for the shutdown and investigation of the Trojan Nuclear Plant was based on six events at the Trojan plant involving electrical equipment.
All of these events have been investigated in accordance with normal NRC inspection procedures.
In each case, the results of the investigations were documented in inspection reports.
In one case, the inspection resulted in an enforcement action being taken against Portland General Electric Company by the NRC. The relevant details of each of these events are discussed below:
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I 1.
On April 20, 1981, an slectrician attempted to use a multi-meter, mistakenly set to a milliamp scale, to measure the voltage across the 480-volt terminals of a motor control center. The low voltage device applied to the high voltage terminals had the effect of a short circuit, which caused an electrical flash in a breaker and resulted in burns to the electrician's 0608v @
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face and hands. This individual was taken to the local hospital where he was treated for first and second-degree burns of the left hand.
Flash burns of the face, neck, and chest were also treated. The individual returned to work on May 5, 1981.
There was minor damage to the motor control center that caused a loss of normal feedwcter control. This resulted in an automatic reactor shutdown when the steam generator water level decreased to a low level set point.
The NRC resident inspector reviewed the event and summarized his findings in IE Inspection Report No. 50-344/81-09 as follows:
"On April 20, 1981, while troubleshooting starting problems of Service Water Booster Pump C, a plant electrician inadvertently shorted over the phases of a breaker associated with the pump. The worker was attempting to measure the voltage between the 8 phase and ground with a digital multimeter.
The worker apparently had used the milliampere jack which would have caused a direct short through the meter. The arc drawn on the B phase stab of the breaker caused a flashover to the other phases, and, thereby, shorted the breaker out. The flash caused superficial 1st and 2nd degree burns on the workman's left hand and chest.
"The shorting out of the breaker caused a feeder breaker to Motor Control Center B25 to open. Tha loss of power to B25 interrupted power to instru-ment busses YO1 and YO3 which provide control power to nonvital loads.
This caused the recirculation valves on the condensate pumps whose control power is supplied by Y01 and YO3 to open, this subsequently lowered flow 4
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of feedwater to the steam generators and the reactor tripped on receipt of a low low level signal in C steam generator.
" Power was subsequently restored to YO1 and YO3, meanwhile the plant responded normally to the trip with all safety-related equipment available.
The licensee after determining the cause of the trip, and placing affected equipment back in service, brought the plant back to power operation approximately seven hours after the plant trip.
"No items of noncompliance or deviations were identified."
No safety-related equipment was affected by this event other than the service water booster pump, which was out of service for the trouble-shooting activities already described.
2.
On February 26, 1981, a blown fuse, located in the central board annun-ciator test circuit, caused all of the alarm lights on the associated panels to illuminate. This test circuit is provided so that all of the alarms on the panel can be tested by pushing a single button.
In this instance, the malfunction of the test circuit caused all of the panel alarms to remain energized. The operator, who was unable to reset the energized alarm lights, declared the control board annunciatiors out of service and initiated a local emergency. This was a prudent response under the circumstances and no unsafe actions were taken.
As it turned out, no safety-related equipment had actually malfunctioned during the 15
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. der.lared inoperable.
The subject alarm panel also remained N nctional because it is designed so that an actuated alarm will indicate subsequent alarms by flashing on and off.
The NRC Inspector's review of this event was summarized in Inspection Report No. 50-344/81-09 as follows:
"The inspectors examined the licensee action taken as a result of the control board annunciators failing to reset after testing on Thursday, February 26, 1981.
The circumstances were initially classified as an unusual event as described in the licensee's emergency response plan.
Testing performed by the licensee since the event has indicated that the alarm features of the control board annunciators were still functional and alarms would have been indicated in the control room even though the reset feature following a system test was not functional.
The reset feature failed to function as a result of a blown fuse in the test / reset button circuit.
The fuse was rated at 4 amps.
Measurements of the test current made by the licensee indicate that under normal test conditions the annunciator test / rest.;ircuit draws approximately 4 amps. This situation was discussed with the manufacturer and a recommendation was made to install a 5 amp fuse. The 5 amp fuse was installed and no problems l
have occurred is a result o" periodic annunciator testing since the February 26, 1981 incident. The licensee has initiated facility design change, RDC 81-042, which when completed will reorganize the annunciators into five separate zones, each zone having its own test / reset button 4
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g circuit. This design change will significantly reduce the current through the test / reset circuit and at the same time prevent a single fuse failure from affecting all annunciator test / reset circuits.
"No items of noncompliance or deviations were identified."
During a surveillance test of a containment spray pump on January 22, 3.
1981 the cooling fans associated with the pump failed to start auto-matically due to a tripped breaker (Licensee Event Report 81-04).
The fans started when the breaker was reset. Subsequent electrical testing showed that the fans operated normally. The NRC resident inspector reviewed the event and summarized his findings in Inspection Report No.
50-344/81-08 as follows:
"The licensee has examined the circuitry for the B containment spray pump fan cooling unit thermal overload protection.
No excessive current or faults could be found, and the exact cause could not be determined.
After resetting the thermal overloads, the fans started and functioned Additional investigative effort by the lice 1see had included normally.
placing a recorder in the circuitry to detect any possible overloads; no indications were recorded during the period the recorder was in use.
"No items of noncompliance or deviations were identified."
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4 This event did not have a significant effect on safety because the building ventilation was adequate to prevent the spray pump from overheating without the fans.
In addition, a redundant con *.ainment spray pump remained fully functional.
4.
On December 12, 1980, a blown fuse was found in the breaker control power circuit for the vent supply fan for the turbine-driven auxiliary feedwater pump room (Licensee Event Report 81-01).
The ventilation fan operated satisfactorily when the fuse was replaced.
The NRC resident inspector's review of this evant was summarized in Inspection Report No. 50-344/81-05 as follows:
"The control power circuit to the ventilation supply fan was checked by licensee personnel for shorts, grounds, or overcurrent conditions.
No faults could be found that would have blown the fuse, and the fan tested satisfactorily after the fuse was replaced.
"No items of noncompliance or deviations were identified."
This ventilation fan is designed to start if the turbine-driven auxiliary feedwater pump is needed and is provided to prevent this feedwater pump from overheating.
However, the temporary loss of this fan is of minimal safety significance since adequate ventilation could have been supplied to the turbine-driven feedwater pump by opening the door to the pump room.
A second auxiliary feedwater system was also available and remained fully functional.
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7-5.
On December 31, 1980, repeated cycling of worn contacts in a motor control center breaker caused electrical arcing that ignited dust and a small plastic dust collector located near an electrical bus (Licensee Event Report 80-28). The fire, which was promptly extinguished, caused minor damage to the bus work. The motor control center that supplies power to certain safety-related equipment remained functional, but was removed from service for five and one-half hours while repairs were made.
Removal of this equipment from service for limited time peri'Js is permit-ted by the plant technical specifications because backup equipment is available for each of the affected safety components. The resident inspector reviewed the event and the corrective action. The results of the review documented in Inspection Report No. 50-344/81-09 are as follows:
"LER 80-28 (Closed): The licensee completed an engineering evaluation of the circumstances and corrective action taken regarding the breaker fire in Motor Control Center B22. The evaluation concludes that the switchgear is properly sized and should safely handle the currents associated with operation of connected plant loads. The study recommends that preventive maintenance procedures be examined to provide for the inspection of the bus work in the vicinity of the stab connection when breaker maintenance is performed.
Should the bus work tin plating be worn off, the resulting contact between the aluminum base metal and the stab connector would This condition in provide a higher than normal resistance contact.
conjunction with the rapid cycling of the load such as repeated starting The of a large electrical motor, could result in contact overheating.
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. f stu(y ciso recommends that operating procedures be reviewed to verify that they contain appropriate lilitations on the number of starts large electrical motors are permitted in specified time intervals.
This limit-ation is primarily for motor protection, but should also minimize the potential for bus work heating during starting current transients. The procedure reviews and any additional testing of the switchgear (if required) will be coupleted during the 1981 refueling outag?
"No items of noncompliance or deviations were identified."
6.
On October 3, 1980, the licensee discovered that the automatic start signal, which starts both trains of auxiliary feedwater pumps on low steam generator water level, had been disabled by a wiring error (Licensee Event Report 80-20). The discovery was made when the steam generator water level decreased to the signal actuation point following a reactor trip.
(The water level drop resulted from water shrinkage from cooldown and is expected in this type of reactor.) The auxiliary feed-water pumps were started manually by the operators as part of their routine procedures, although in this case they were not needed.
The error occurred when the electrical leads transmitting the signal were connected to the wrong terminals following the 1980 refueling outage. Although the problem was caused by a human error, the main concern in this instance was that the error was not detected by the testing that is required to be conducted on all safety-related l
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1 systems following maintenance.
This event was reviewed in consider-able detail by NRC. The site inspector's review was summarized in the Inspection Report No. 50-344/80-29 as fo11cws:
"The inspectors examined the long term corrective action taken by the licensee to preclude recurrence of the incident described in the LER.
The basic cause of the LER was the personnel wiring error which was not detected by an appropriate test when the safety-related automatic start of the auxiliary feedwater pumps was reconnected following the completion of meintenance in the steam generators.
Facility procedures require the testing of all safety-related systems, structures and components upon return to service following maintenaner..
In actual implementation of these procedures, the testing of safety-related equipment upon return to service was limited to the systems, components and instrumentation specified in the technical specifications.
The low level automatic start feature of the auxiliary feedwater pumps was not a function specified by the facility technical specifications. The licensee's quality assurance program is committed to ANSI N18.7-1976 which in section 5.2.6 requires that when safety related equipment is returned to service, operating personnel shall place the equipment in operation and verify and document its functional acceptability. The weakness in the implementation of procedure (AO-3-14) which limited the safety-related equipment to that specified in the technical specification is in noncompliance with the procedure itself in view of the Quality Assurance Program commitment to ANSI N18.7-1976.
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. F The specific correction taken by the licensee to correct the situation described above has been to emphasize and revise, as appropriate, Admin-istrative Order No. 3-14, Safety-Related Equipment Outages, and Adminis-trative Order No. 6-2, Bypass of Safety Functions, to clearly specify that all safety related equipment must be verified functional upon return to service following maintenance, not just safety-related equipment, components or instrumentation required by the technical specifications.
As applicable, the methods for verifying functionability include, operation of the component in accordance with an appesved test procedure, performance of an installation check or an independent verification check.
In addition to the above, the licensee's technical specificatic..s have been amended to require that all automatic starting features of the auxiliary feedwater system be operable and tested at a specified surveillance frequency during modes 1, 2 and 3.
"One item of noncompliance was identified by the licensee as described above.
No deviations were identified."
Although this event revealed a deficiency in the licensee's procedures, it did not have a significant effect on public safety.
The auxiliary feedwater system continued to be capable of performing its intended function.
In this instance, the main feedwater system did not shut dow t, so there was no need for the auxiliary feedwater system.
However, if a loss of main feedwater had occurred, an automatic start feature for the loss of the main feedvater pumps would have started the auxiliary feedwater 6
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. j system In addition, the manual auxiliary feedwater start can be considered to be a reliable backup for this system because the steam generators will continue to provide adequate cooling for 30 minutes following a reactor trip (FSAR Fig. 15.2-31) without the adaition of any feedwater.
In this case, the control operator, following the normal post trip procedures,
.iccomplished a manual start of the auxiliary feedwater in about one minute.
The number of electrical equipment problems reported by Portland General Electric over the time period covered by these events is not considered unusual for a plant such as Trojan with its thousands of electrical components. None of these events repre',ented a significant reduction in the level of protection provided for public health and safety.
In each case, backup systems and measures were available to provide the functions of the affected components.
In each case, the licensee has provided appropriate corrective action.
In my judgment, the inspections already performed by the NRC staff, as well as the corrective actions taken by the licensee, described in tho-pre-viously referenced accuments have adequately addressed the events identified in the Trojan Decommissioning Alliance's communication.
On that basis, I deny the petition.
A copy of this Decision and its enclosures will be placed in the Commission's public document room at 1717 H Street, NW, Washington, DC 20555 and in the local public document room for the Trojan facility, located at l
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Multnom.ah County Library, Social Scienca & Science Department, 801 SW 10th Avenue, Portland, Oregon 97205.
A copy will also be filed with the Secretary of the Comission for review in accordance with 10 CFR 2.206(c) of the Commission's regulations, s
As provided in 10 CFR 2.206(c) of the Commission's regulations, this Decision will constitute the final action of the Commission twenty-five (25) days after the date of '.ssuance, unless the Commission, on its own motion, institutes a review of this Decision within that time.
FOR THE NUCLEAR REGULATORY COMISSION 2
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C James H. Sniezek, Acting Director
$dfice of Inspection and Enforcement Dated at Bethesda, Maryland this S/ day of May 1981.
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