ENS 49615: Difference between revisions
Jump to navigation
Jump to search
StriderTol (talk | contribs) (Created page by program invented by Mark Hawes) |
StriderTol (talk | contribs) (Created page by program invented by StriderTol) |
||
| Line 16: | Line 16: | ||
| event date = 12/07/2013 23:55 CST | | event date = 12/07/2013 23:55 CST | ||
| last update date = 12/08/2013 | | last update date = 12/08/2013 | ||
| title = Average Power Range Monitors Declared Inoperable Due | | title = Average Power Range Monitors Declared Inoperable Due to Non-Conservative Power Value | ||
| event text = This report is being made pursuant to 10CFR50.72(b)(3)(v)(A), event or condition that at the time of discovery could have prevented the fulfillment of a safety function of systems that are needed to shutdown the reactor and maintain it in a safe shutdown condition. A scheduled load reduction for surveillance testing and control rod sequence exchange was in progress. During the control rod sequence exchange, the core monitoring software system (3DMonicore) was used to obtain a 'case' which records various calculated and actual core parameters (i.e. core thermal power, Power Range Monitor indication). The 'case' data is used to evaluate the Technical Specification (TS) Surveillance Requirement (SR) acceptance criteria for SR 3.3.1.1.2 to verify the absolute difference between the average power range monitor (APRM) channels and the calculated power is less than or equal to 2% rated thermal power (RTP) while operating at greater than or equal to 25% RTP. The 'case' showed that all 3 A RPS Trip System APRM channels exceeded the allowable 2% difference threshold in the non-conservative direction (i.e. APRM power reading less than calculated thermal power, difference of 2.9, 3.1, and 2.5% respectively). TS 3.3.1.1 requires at least 2 operable APRM channels per trip system (there are 2 RPS trip systems, A and B). At least 1 of 2 TS required APRM channels are required to maintain the Safety Function (i.e. SCRAM). In this situation, none of the A RPS TS required APRM channels met their SR and were declared inoperable. TS 3.3.1.1 allows delaying entry into the associated Condition and Required Action for this inoperability for up to 2 hours when the inoperability is solely due to APRM indication not within the 2% limit; therefore no TS Required Action tracking timeclocks were entered. A confirmatory 'case' was performed that validated that the subject SR was not met. Prompt action was taken to restore the APRM indications to within limits (this action took approximately 22 minutes to complete) and the subject APRMs were declared operable, restoring the A RPS Safety Function. | | event text = This report is being made pursuant to 10CFR50.72(b)(3)(v)(A), event or condition that at the time of discovery could have prevented the fulfillment of a safety function of systems that are needed to shutdown the reactor and maintain it in a safe shutdown condition. A scheduled load reduction for surveillance testing and control rod sequence exchange was in progress. During the control rod sequence exchange, the core monitoring software system (3DMonicore) was used to obtain a 'case' which records various calculated and actual core parameters (i.e. core thermal power, Power Range Monitor indication). The 'case' data is used to evaluate the Technical Specification (TS) Surveillance Requirement (SR) acceptance criteria for SR 3.3.1.1.2 to verify the absolute difference between the average power range monitor (APRM) channels and the calculated power is less than or equal to 2% rated thermal power (RTP) while operating at greater than or equal to 25% RTP. The 'case' showed that all 3 A RPS Trip System APRM channels exceeded the allowable 2% difference threshold in the non-conservative direction (i.e. APRM power reading less than calculated thermal power, difference of 2.9, 3.1, and 2.5% respectively). TS 3.3.1.1 requires at least 2 operable APRM channels per trip system (there are 2 RPS trip systems, A and B). At least 1 of 2 TS required APRM channels are required to maintain the Safety Function (i.e. SCRAM). In this situation, none of the A RPS TS required APRM channels met their SR and were declared inoperable. TS 3.3.1.1 allows delaying entry into the associated Condition and Required Action for this inoperability for up to 2 hours when the inoperability is solely due to APRM indication not within the 2% limit; therefore no TS Required Action tracking timeclocks were entered. A confirmatory 'case' was performed that validated that the subject SR was not met. Prompt action was taken to restore the APRM indications to within limits (this action took approximately 22 minutes to complete) and the subject APRMs were declared operable, restoring the A RPS Safety Function. | ||
The licensee notified the NRC Resident Inspector and the Illinois Emergency Management Agency. | The licensee notified the NRC Resident Inspector and the Illinois Emergency Management Agency. | ||
Latest revision as of 21:52, 1 March 2018
| Where | |
|---|---|
Lasalle  Illinois (NRC Region 3) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(v)(A), Loss of Safety Function - Shutdown the Reactor | |
| LER: | 05000374/LER-2013-003 |
| Time - Person (Reporting Time:+0.23 h0.00958 days <br />0.00137 weeks <br />3.15054e-4 months <br />) | |
| Opened: | Jason Depriest 06:09 Dec 8, 2013 |
| NRC Officer: | Donald Norwood |
| Last Updated: | Dec 8, 2013 |
| 49615 - NRC Website
| |