ENS 43331
ENS Event | |
|---|---|
01:17 May 1, 2007 | |
| Title | |
| Event Description | At 1007 on the morning of 04/30/2007, operations personnel identified an adverse trend in Primary Containment Nitrogen makeup frequency. The subsequent investigation determined that Primary Containment Nitrogen was leaking backwards thru V22-0017 HPCI Turbine Exhaust Line Stop-Check Valve and V22-0016 HPCI Exhaust Check Valve, via the HPCI exhaust vacuum breakers and the environment of the HPCI room via the turbine seals.
The degradation of V22-0016 and V22-0017 constitute a condition that at the time of discovery could have prevented the fulfillment of the safety function of structures or systems that are needed to mitigate the consequences of an accident. (50.72(b)(3)(v)(D)). At 2017 on the evening of 04/30/2007, V22-0017 HPCI Turbine Exhaust Line Stop-Check Valve and V22-0016 HPCI Exhaust Check Valve were declared inoperable due to Primary Containment Nitrogen leakage as described above. At 2032 on the evening of 04/30/2007, V22-0017 HPCI Turbine Steam Exhaust Line Isolation was shut to isolate Primary Containment Nitrogen leakage. With V22-0017 shut, HPCI is INOPERABLE and Unavailable. The licensee is in a 14 day LCO under section 3.6.1.3 for Primary Containment Isolation Valves (PCIV). However, they are in a 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> LCO for having "A" core spray and HPCI inoperable, concurrently. The licensee expects to have "A" core spray restored during dayshift on 5/1/07. Additionally, the licensee is in a 7 day LCO for EDG OOS. The licensee notified the NRC Resident Inspector.
The licensee provided a correction to the TS LCO statement referenced in the initial report. The 14 day LCO is not under section 3.6.1.3 for Primary Containment Isolation Valves (PCIV). The correct LCO statement is 3.5.1 for ECCS Operating. The licensee will notify the NRC Resident Inspector. R3DO (Lipa) notified.
The purpose of this notification is to retract a previous report made on 5/01/07 at 0039 (ET) (EN 43331). Notification of this issue to the NRC on 5/01/07 was initially made due to the High Pressure Coolant Injection (HPCI) system being declared inoperable due to a primary containment nitrogen leak. Specifically, at the time, operations personnel identified an adverse trend in Primary Containment Nitrogen makeup frequency. The subsequent investigation determined that Primary Containment Nitrogen was leaking backwards thru V22-0017, HPCI Turbine Exhaust Line Stop-Check Valve, and V22-0016, HPCI Exhaust Check Valve, via the HPCI exhaust vacuum breakers and the environment of the HPCI room via the turbine seals. Since the initial report, Engineering has determined that the HPCI system was capable of performing its safety function. This conclusion is based on the fact that V22-0016 and V22-0017 open during HPCI operation and the closing function is no longer included in the 10CFR50 Appendix J Testing Program since the line does not constitute a potential primary containment atmospheric pathway during and following a Design Basis Accident (DBA). MO2290A and MO2290B (HPCI Turbine Steam Exhaust Vacuum Breaker motor operated valves), which are Appendix J Program valves, communicate with both the HPCI exhaust line and the torus air space and will isolate during a Design Basis Accident (DBA). Therefore, the HPCI injection was still operational and the HPCI exhaust line will not communicate directly with the containment atmosphere and will not provide a containment atmospheric pathway during and following a Design Basis Accident. All safety design functions of V22-0016 and V22-0017 were met. Additionally, as-left valve closure testing on both V22-0016 and V22-017 were successful and both valves were fully operable. This event is not considered a Safety System Functional Failure and is not reportable to the NRC as a Licensee Event Report per 10 CFR 50.73. The licensee notified the NRC Resident Inspector. Notified R3DO (A.M. Stone). |
| Where | |
|---|---|
Duane Arnold  Iowa (NRC Region 3) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | |
| Time - Person (Reporting Time:+-0.63 h-0.0263 days <br />-0.00375 weeks <br />-8.62974e-4 months <br />) | |
| Opened: | Brian Hupke 00:39 May 1, 2007 |
| NRC Officer: | Joe O'Hara |
| Last Updated: | Jun 11, 2007 |
| 43331 - NRC Website
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Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (98 %) |
| After | Power Operation (98 %) |
Duane Arnold with 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | |
WEEKMONTHYEARENS 528812017-08-01T14:34:0001 August 2017 14:34:00
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