ENS 51595
ENS Event | |
|---|---|
19:43 Dec 9, 2015 | |
| Title | Reactor Recirculation Loop Flow Transmitters Out of Tolerance |
| Event Description | During surveillance testing, 2 reactor recirculation loop flow transmitters, which input to the Average Power Range Neutron Monitors (APRM's) associated with the 'A' Reactor Protection Trip System (RPS), were found out of tolerance in the non-conservative direction.
Non-conservative reactor recirculation flow setpoints for all 'A' side APRM's results in a loss of safety function for the APRM Neutron Flux High (Flow Biased) trip function of RPS. All instruments were adjusted back to within tolerance as allowed by the procedure, restoring the RPS safety function. Extent of condition and instrument drift issues are under evaluation via the corrective action process. This is an 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> reportable event under 10CFR50.72(b)(3)(v)(A) - Any event or condition that at the time of discovery could have prevented the fulfillment of the safety function of structures or systems that are needed to: (A) Shutdown the reactor and maintain it in a safe shutdown condition. The NRC Senior Resident Inspector has been notified.
On the basis of a subsequent engineering evaluation, which reviewed the uncertainties considered within the setpoint calculations and the sequencing of the transmitter calibrations, it was determined that the APRM channels and Control Rod Block Monitor instrumentation associated with the Neutron Flux High (Flow Biased) function were unaffected by the out of calibration condition. Technical Specification (TS) Table 3.3.1.1 FUNCTION 2.b requires two (2) APRM Neutron Flux High (Flow Biased) channels per RPS trip system. TS Table 3.3.2.1 FUNCTION 1.a requires two (2) Rod Block Monitor [RBM] Upscale channels. These TS requirements were met upon discovery of this condition. The past-operability of the RPS and RBM instrumentation was unaffected by this condition. In addition, the engineering analysis confirmed that the Neutron Flux High (Flow Biased) allowable values in the Core Operating Limits Report (COLR) and the TRM were not exceeded. Therefore, there was no loss of safety function, and this condition was not reportable pursuant to 10 CFR 50.72(b)(3)(v)(A), as an event or condition that could have prevented fulfillment of a safety function. FitzPatrick is retracting ENS 51595. The degraded flow transmitters have been replaced, and the operability determination for the condition has been revised. All RPS and RBM instrumentation remain operable. The NRC Resident Inspector has been notified. Notified R1DO (Bickett). |
| Where | |
|---|---|
Fitzpatrick  New York (NRC Region 1) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(v)(A), Loss of Safety Function - Shutdown the Reactor | |
| Time - Person (Reporting Time:+2.75 h0.115 days <br />0.0164 weeks <br />0.00377 months <br />) | |
| Opened: | David A. Richardson 22:28 Dec 9, 2015 |
| NRC Officer: | Jeff Herrera |
| Last Updated: | Jan 29, 2016 |
| 51595 - NRC Website
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Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
WEEKMONTHYEARENS 515952015-12-09T19:43:0009 December 2015 19:43:00
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