ENS 44182
ENS Event | |
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21:00 Apr 30, 2008 | |
Title | |
Event Description | Two emergency diesel generators found inoperable while two trains of residual heat removal are required to be Operable for core cooling.
On 4/30 at 1600 it was discovered that the level in Emergency Diesel Generator Fuel Oil Storage tanks were not trending together. The two underground fuel oil tanks have a capacity of 35,000 gallons each (useable volume of 34,674 gallons). The tanks are connected with a siphon line between the tanks to ensure a passive means of transfer so one emergency diesel can use both tanks. The siphon line does not appear to be transferring fuel oil. KPS is in a refueling outage and in REFUELING SHUTDOWN mode with the vessel drained to 6" below the flange for reactor vessel reassembly. Both trains of RHR are required to be OPERABLE per TS 3.1.a.2.B. Technical Specification 3.7.c states that when its normal or emergency power source is inoperable, a system, train or component may be considered OPERABLE for the purpose of satisfying the requirements of its applicable LCO provided: 1. Its corresponding normal and emergency power source is OPERABLE; and 2. Its redundant system, train, or component is OPERABLE. Kewaunee Power Station (KPS) Technical Specifications Section 3.7.a.7 states that the reactor shall not be made critical unless both diesel generators are operable. The two underground storage tanks combine to supply at least 35000 gallons of fuel oil for either diesel generator and the day tanks for each diesel generator contain at least 1,000 gallons of fuel oil. The current volume is 29,700 gallons in Tank A and 21,500 gallons in Tank B. Based on two trains found inoperable, this is reportable under: 10 CFR 50.72(b)(3)(ii) (8-Hr) 10 CFR 50.72(b)(3)(v)(B) (8-hr) Per TS 3.1.a.2.B the condition must be fixed immediately. Troubleshooting/investigation is in progress to determine repairs. Cause is being investigated. Condition was found during engineering review of logs taken during operator rounds. The licensee notified the NRC Resident Inspector.
EN 44182 provided notification that the emergency diesel generator (EDG) fuel oil tanks were not capable of supplying the combined volume of fuel oil (35,000 gallons) from two storage tanks to either EDG as required by Technical Specification (TS) 3.7.a.7 for EDG operability. That notification was based on a conservative determination that a siphon line, which connects the two fuel oil storage tanks, was nonfunctioning. TS 3.7.a.7 requires both EDGs to be operable when the reactor is critical. Although the reactor was in refueling shutdown mode at the time of this event (i.e., not critical, and therefore not in the mode of applicability for TS 3.7.a.7), the EDGs provide a support function (emergency power) for the Residual Heat Removal (RHR) system; two trains of which were required to be operable for core cooling per TS 3.1.a.2.B. A subsequent review confirmed that the capability to transfer fuel from either storage tank to either EDG existed independent of the siphon line. The siphon line is not needed for transferring fuel oil from either tank to either EDG. There are alternate means available to transfer fuel oil to the EDGs; sufficient time is available to implement these alternate means of fuel oil transfer within the time available. Additional fuel oil supply margin existed due to the mode of operation at the time (refueling shutdown). The 35,000 gallon TS requirement is based on the expected fuel consumption of one EDG operating for seven days at continuous rated load, thus ensuring adequate time to restore off-site power or to replenish fuel. The amount of fuel in the storage tanks was sufficient for the EDGs to be capable of performing their support function for RHR in the refueling shutdown mode. As such, both RHR trains remained operable and TS 3.1 a.2.B was satisfied. Consequently, this condition did not meet the reportability criteria in 10 CFR 50.72. As a result, the notification made on 4/30/2008 (EN 44182) is hereby retracted. The licensee notified the NRC Resident Inspector. Notified the R3DO (Peterson). |
Where | |
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Kewaunee ![]() Wisconsin (NRC Region 3) | |
Reporting | |
10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat | |
Time - Person (Reporting Time:+1.87 h0.0779 days <br />0.0111 weeks <br />0.00256 months <br />) | |
Opened: | Andrew Smolinski 22:52 Apr 30, 2008 |
NRC Officer: | Joe O'Hara |
Last Updated: | May 14, 2008 |
44182 - NRC Website
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