ML20081M346
| ML20081M346 | |
| Person / Time | |
|---|---|
| Site: | McGuire  |
| Issue date: | 11/04/1983 |
| From: | Tucker H DUKE POWER CO. |
| To: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| RO-369-83-84, NUDOCS 8311170226 | |
| Download: ML20081M346 (4) | |
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- 'e DUKE POWER GOMPANY P.O. HOx 33180 CHARLOTrE, N.C. 28242 HALH. TUCKER TELEPHONE
.g mo-g gQV N emB'er ' 4, 1983 Mr. James P. O'Reilly, Regional Administrator U. S. Nuclear Regulatory Commission Region II 101 Marietta Street, NW, Suite 2900
' Atlanta, Georgia 30303
Subject:
McGuire Nuclear Station Unit 1 Docket No. 50-369 LER/RO-369/83-84 (Revised)
Dear Mr. O'Reilly:
Please find attached Reportable Occurrence Report R0-369/83-84 (Revised). This report concerns Technical Specification 3.6.2, "Two Independent Containment Spray Systems Shall Be Operable..."; and Technical Specification 3.7.4, "At Least Two Independent Nuclear Service Water Loops Shall Be Operable." LER Form
-366 is not attached since no changes were made to this form. This incident was considered to be of no significance with respect to the health and safety of the public.
Very truly yours, 8.[_Xu Hal B. Tucker PBN/php Attachment ec: Document Control Desk U. S. Nuclear Regulatory Commission Washington, D. C. 20555 Mr. W. T. Orders NRC Resident Inspector McGuire Nuclear Station
.INPO. Records Center Suite 1500 1100 circle 75 Parkway Atlanta, Georgia 30339 OFFICIAL COffb 8311170226 831104
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PDR ADOCK 05000369 S
JP0/HBT/PBN November 4, 1983 Duke Power Company McGuire Nuclear Station Reportable Occurrence Report No. 369/83-84 Report Date: October 14, 1983 Facility: McGuire Unit 1, Cornelius, North Carolina Identification:
Both Trains of Containment Spray System Inoperable
==
Description:==
While in Mode 1 at 100% power on September 28, 1983, Containment Spray System-(NS) Train B was declared inoperable. This declaration was made following the identification of a loss of power indication for the DC power supply to the Train B Containment Pressure Control System (CPCS) pressure transmitter. Two trains of the NS System are required to be operable by Technical Specification 3.6.2.
On September 29, 1983, in order to perform a retest of Nuclear Service Water System (RN) valve 1RN-68 following maintenance, an operator was sent to inspect Nuclear Service Water System Pump 1A.
The operator noted water in the oil reservoir for the outboard pump bearing and reported this to the Control Room.
The decision to declare the pump inoperable was made by the Shift Supervisor and the Assistant Operating Engineer.
Both trains of the RN System are required to be operable by Technical Specification 3.7.4.
The RN System provides support necessary to the operability of the NS System by cooling the NS heat exchanger and the air handling unit motor cooler for the NS pump. The inoperable declaration of RN Pump 1A therefore caused the NS Train A to be inoperable, resulting in no operable NS trains and placing the unit outside the Action Statement of Technical Specification 3.6.2.
This inoperability was confined to the recirculation mode of operation of the NS System. When a tsmiting
' Condition for Operation (LCO) and Action Statement are not met, the unit is required to be placed in a mode in which the specification does not apply. This action is required to be initiated within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />, pursuant to Technical Specifica-tion 3.0.3.
i The impact of the inoperable RN train upon the single remaining operable NS train i
was not realized when RN Pump 1A was tagged out.
Therefore, the requirements of Technical Specification 3.0.3 were not met.
The discovery that both NS trains had in fact been inoperable was made when NS Train B was being cleared from the Technical Specification Action Item Log (TSAIL). This situation existed for approximately five hours.
Evaluatien: Troubleshooting of the DC power supply for the CPCS Pressure Transmitter revealed that it was not providing the required 48 volt DC output. With the pressure transmitter unable to provide a signal to the alarm module, the relays controlled by this module (which provide the open permissive for two NS valves) could not be
. energized.
Tenporary jumpers were placed across the contacts necessary to energize the relays providing the open permissive signal to the NS valves, restoring Train B to operable status.
This action was taken when it appeared that there would be a delay in obtaining a new power supply. The interlock function of the CPCS was still operable since the pressure transmitter supplying the stop/ start permissive' signal to the NS pump was still operable.
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November'4, 1983 Whenwaterwasdiscoveredintheoilreservoirfortheoutboardbearinghf-
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RN Pump 1A, the train was declared-inoperable and pump motor breakers were opened. Sludge (mud and possible organic growth) was found clogging the drain line for the outboard seal' catch basin.- The RN System takes suction from untreated lake water. The clogging of the drain line is thought to have gradually accumulated from pump seal leakage.
When RN Pump 1A was declared inoperab'le,'NS Train B was still out of service.
At the time that RN. Train.A was declared inoperable, the impact upon NS,, Train"A was not considered.
RN Train A provides cooling water to,the heat exchanger and air handling unit motor cooler for NS Pump 1A.
NS Train A is rendered inoperable by the loss of RN Train A.
The Technical Specification Reference Manual - Section IV provides a list of related Technical Specifications with applicable modes' to be considered when a system is declared inoperable. As a result of this incident, the list of related Technical Specifications was reviewed and it was discovered that the RN System's impact upon NS (Technical Specification 3.6.2) was not addressed by the reference manual.
Other systems which depend upon RN for operability and a're required during theMode1aretheChemicalandVolumeControl(NV). System,AuxiliaryFeedQater (CA) System, Component Cooling Water (KC) System, Control Area Ventilation (VC)
System and the Diesel Generator (D/G). All of these systems had the redundant train operable when RN train became inoperable.
The requirement exists to declare dependent systems inoperable when a support system is taken out of service. The common but not totally uniform approach used when declaring a support system inoperable is to list dependent systems 4
in the TSAIL.
This approach was not applied when RN Pump 1A was declared inoperable.
Compliance with Technical Specification Action Statement 3.8.1.1 was also not achieved during this incident. With D/G 1A inoperable due to RN Pump 1A, the Action Statements a) and c) of the associated specification.were applicable.
This required a)' that an active test of D/G 1B's operability be performed by starting the D/G and verifying generator parameters, and c) that required equipment relying on D/G 1B as an emergency power source, and the turbine-
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driven CA pump, be verified to be operable. Since the dependency of systems upon RN Train A was not evaluated and D/G 1A was not declared in the TSAIL, these actions were not met.
Corrective Action: While a new power supply was being obtained (Lambda Model LCS-CC-48; 48 VDC, 3.7 amp power supply) for the pressure transmitter, the relays controlled by the alarm module were energized by the use of jumpers. This restored NS Train B by simulating a constant open permissive for the two affected NS valves.
The new power supply was installed and the jumpers removed on September 30, 1983.
These actions restored the pressure transmitter for NS Train B to operable status.
The RN Pump 1A outboard seal catch basin drain line was cleated. The bearing was inspected for damage and flushed with oil.
The oil reservoir was then refilled with clean oil.
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JP0/HBT/PBN Novzmbrr 4, 1983 In order to prevent future failures to identify inoperable dependent systems when a support system is declared inoperable, a memorandum was issued on September 30, 1983. This memorandum was addressed to all Senior Reactor Operator license holders, and stated the policy of declaring all dependent systems inoperable (and making the appropriate TSAIL entries) whenever a support system is declared inoperable. Technical Specification Reference Manual - Section IV was updated to include the impact of RN System on NS System operability.
Safety Analysis: When the NS Train B was initially declared inoperable, Train A was fully functional and capable of performing the designed safety function if required. This was not the case for four hours and forty minutes on September 29, 1983. During this time both NS trains were technically inoperable.
The containment pressure response to the design basis LOCA has been analyzed with the following assumptions. These assumptions were selected to result in the most severe containment response resulting from the NS failure, along with taking credit for a very conservative operator responsa time to perform actions to restore NS Train B.
1.
Loss of off-site power.
2.
Loss of D/G A due to loss of RN Train A.
3.
Ice condenser initial ice mass equal to Technical Specification value.
4.
NS Train B restored at one hour.
5.
Residual Heat Removal (ND) Train B containment spray available following transfer to sump recirculation mode.
The operator response to this event would include an early recognition of both trains of NS having failed to deliver any flow to the containment spray headers.
NS pump B would be up to speed; however, the discharge valves would remain closed due to the CPCS interlock failure. An operator would be dispatched to manually open the NS valves. This operator action was conservatively assumed to occur at one hour, although on a realistic basis a much earlier response would be expected.
The result of this analysis is a peak containment pressure of 11.4 psig at 5350 seconds. Significant margin to the containment design pressore of 15 psig was maintained. This result demonstrctes that the NS system is not required for containment pressure control during the first hour following the design basis LOCA. Containment pressure is limited by the large energy sink of the ice condenser during the first hour.
Based on the above analysis, the containment design pressure would not have been exceeded in the event of a design basis LOCA coincident with a loss of off-site power, had such an event occurred during the time interval with both NS trains inoperable. As such, the health and safety of the public were not affected.