05000305/LER-2006-007
| Docket Number | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 3052006007R00 - NRC Website | |
FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER (6 PAGE (3)
Event Description:
On June 13, 2006, with the station at approximately 100% power, it was determined that Surveillance Procedure SP-47-310, Reactor Coolant System RTD Cross Calibration, has the potential to exceed the 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> allowable LCO time.
This surveillance procedure removes all four narrow range channels of RCS [AB] temperature from service during plant heatup, (from approximately 350 degrees F to 500 degrees F), thus rendering all channels of Tavg inoperable. Item 2.b of Technical Specification Table 3.5-4 (Instrument Operating Conditions For Tavg with Safety Injection). With less than the minimum channels operable, the LCO requires that the plant be placed in HOT SHUTDOWN. If the minimum conditions are not met within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, the LCO requires the plant be placed in a COLD SHUTDOWN condition. Therefore, if this surveillance procedure renders Tavg inoperable for greater than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, and plant heatup continues, the LCO is not met.
Historically, performance times for specific steps of SP-47-310 were not recorded, so the precise durations of Tavg inoperability can not be determined. It is conservatively assumed that all previous performances have exceeded the 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> limit. Consequently, when SP-47-310 was performed in November of 2004, station Technical Specification 3.5 was not met.
Event Analysis:
This event is being reported in accordance with 10CFR50.73(a)(2)(i)(B), "Any operation or condition which was prohibited by the plant's Technical Specifications.
This surveillance procedure removes all four narrow range channels of RCS temperature from service for data collection during a plant heatup at a starting temperature between 350 and 380 degrees F, over a minimum span of 150 degrees F, with at least one data set obtained at hot no-load conditions. During the procedure, the plant is not allowed to exceed Hot Shutdown conditions.
During the last three years this procedure was only performed once (during recovery from a refueling outage on November 23, 2004). For that performance, a precise determination of RTD [TE] (and thus Tavg) inoperability time could not be determined. Since the procedure was in progress for 68.6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />, (by Control Room log entries), it is assumed that Tavg inoperability exceeded the 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> limit. The plant was not placed in COLD SHUTDOWN as required, which is a violation of TS 3.5.
There was no safety system function failure involved in this event.
FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER (6 PAGE (3)
Safety Significance:
There were no actual nuclear or radiation exposure consequences from this event.
The affected Tech Spec item is associated with the Engineered Safety Feature (ESF) steam line isolation.
The function of the affected portion of steam line isolation is to isolate a faulty steam line during coincident conditions of safety injection signal, low-low Tavg, and high steam flow. Since both steam lines were isolated during the entire 68.8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> of procedure performance, the function of the affected ESF system had already been met. Therefore, there was no safety significance for this event.
Cause:
Previous application of Technical Specification Table 3.5-4 was that Item 2.b did not apply when the ESF function was otherwise disabled. Therefore, since SI is blocked below 2000 psig during a heatup, the ESF function was disabled, and the Technical Specification item did not apply. During procedure review on June 13, 2006, it was determined that the Technical Specification item did apply.
Corrective Actions:
1. Placed Surveillance Procedure SP-47-310, Reactor Coolant System RTD Cross Calibration, on Administrative Hold until it is corrected.
2. The procedure will be revised to assure it is completed within the allowable 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.
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