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| Start date | Reporting criterion | Title | Event description | System | LER | |
|---|---|---|---|---|---|---|
| ENS 53287 | 25 March 2018 20:16:00 | 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition 10 CFR 50.72(b)(3)(ii)(A), Seriously Degraded | Control Rod Drive Piping Potentially Inoperable | On March 25, 2018 at 1616 hours (EDT), with the reactor in cold shutdown condition, two control rod drive piping lines were determined to be potentially inoperable in the event of a design basis earthquake due to support defects. The control rod drive piping forms a portion of the reactor coolant pressure boundary and primary containment boundary. The supports will be repaired prior to plant startup. This event had no impact on the health and/or safety of the public. The NRC Resident Inspector has been notified. The licensee will notify the Commonwealth of Massachusetts.
The purpose of the notification is to retract ENS notification 53287 made on 03/25/18 for Pilgrim Nuclear Power Station. The previous notification reported that control rod drive (CRD) piping could be potentially inoperable in the event of a design basis earthquake, at the time of discovery, due to piping support defects. Subsequent evaluation has demonstrated that the piping was not inoperable. Specifically, after an engineering evaluation, it has been determined that the CRD Hydraulic System operability was never lost and the system was operable, although non-conforming, based on the support configuration not conforming to the pipe support drawings. The affected pipe supports have been restored or reworked to the proper design condition in accordance with the design drawings. The CRD System has subsequently been restored to a fully operable status. Notified R1DO (Jackson) and IRD MOC (Pham). | Primary containment Control Rod | |
| ENS 51924 | 12 May 2016 20:47:00 | 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | Deterioration of Spent Fuel Pool Rack Neutron Absorbing Material | On May 12, 2016, at 16:47 EDT with the reactor at 100% power and the mode switch in RUN, an assessment of the Spent Fuel Pool racks containing neutron absorbing material concluded that some degradation had occurred. The result is that we cannot assure we are maintaining Keff < 0.95 as required per design. Conservative measures have been implemented to ensure public health and safety. Recent planned testing conducted in the spent fuel pool determined that one rack panel had degradation of the neutron absorbing material in excess of what had been analyzed. An extent of condition review indicated additional potential at-risk locations may exist. Analyses are being performed to determine the potential impact and mitigating actions. Fuel pool conditions are safe and stable. Conservative measures have been implemented and spent fuel safety is maintained. Based on the above, the condition is reportable to the NRC as an Unanalyzed Condition under 10 CFR 50.72(b)(3)(ii), and requires an 8 hour notification. The condition is also reportable in accordance with 10 CFR 50.73 (a)(2)(ii). The licensee has notified the NRC Senior Resident Inspector. The licensee will notify the Commonwealth of Massachusetts. | 05000293/LER-2016-003 | |
| ENS 51456 | 5 October 2015 21:25:00 | 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | Safe Shutdown Analysis for Fire Event - Open Item with Potential to Impact Capability to Operate Motor Operated Valves | At 1725 (EDT) on Monday, October 5, 2015, while updating the site fire safe shutdown analysis report, Pilgrim Nuclear Power Station (PNPS) identified vulnerabilities in two (2) specific fire areas that required a compensatory fire watch. The compensatory fire watches have already been established. The specific concern involves the unlikely scenario that fire forces evacuation of the control room. In addition, it is postulated that motor operated valves cannot be operated from their alternate control location due to spurious operation caused by hot shorts in control wiring. The specific failure mode is described in NRC Information Notice (IN) 92-18. Engineering modifications are under development and scheduled for implementation to address this specific IN 92-18 concern. Based on the above, the condition is reportable to the NRC as an unanalyzed condition that significantly degrades plant safety. As such the condition is reportable under 50.72(b)(3)(ii)(B), and requires an 8 hour notification. The licensee has notified the NRC Resident Inspector. | ||
| ENS 47288 | 22 September 2011 18:52:00 | 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | Salt Service Water Pump Inoperability During Postulated Degraded Voltage Conditions | On Thursday, September 22, 2011 at 1452 (EDT), with the reactor at 100% core thermal power and steady state conditions, Pilgrim Nuclear Power Station (PNPS) conservatively declared both Salt Service Water (SSW) subsystems inoperable when engineering analysis determined that inrush current on pump restart may exceed the thermal overload trip relay settings during certain degraded voltage conditions. A 24-hour Limiting Condition for Operation action statement was entered. Entergy/Pilgrim is in the process of implementing temporary modifications to correct this issue. This potential concern has no impact on public health and safety. This 8-hour notification is being conservatively reported in accordance with 10 CFR50.72(b)(3)(ii)(B). The NRC Resident Inspector has been notified. The licensee will notify the Massachusetts Emergency Management Center.
Event Notification 47288 was conservatively made to ensure that the Eight-Hour Non-Emergency reporting requirements of 10 CFR 50.72 were satisfied pending further evaluation of Salt Service Water (SSW) subsystem operability during certain degraded voltage conditions. Pilgrim Station has subsequently evaluated the impact of the Salt Service Water (SSW) pump motor operating load; potential degraded voltage conditions on thermal overload settings; and pump motor restart requirements; and determined that reasonable assurance of SSW subsystem operability existed. Both SSW subsystems were evaluated to be capable of satisfying the system safety function of providing cooling water to the Reactor Building Closed Cooling Water System heat exchangers during accident and transient conditions. Pilgrim 's evaluation considered manufacturer's data for the thermal overload relays, site specific shop testing, and reliable grid conditions which minimize the potential for extended operation with 4 kV buses operating at just above degraded voltage relay trip settings. This past operability evaluation concluded that the SSW pumps would support continuous operation of the SSW subsystems. Therefore, the initial 50.72 report is being retracted. The licensee will notify the NRC Resident Inspector. Notified the R1DO (Caruso). | Service water | |
| ENS 46933 | 7 June 2011 12:00:00 | 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | Errors in Methodology Used for Emergency Core Cooling System Performance Requirements | On Tuesday, June 7, 2011, at 0800 hours, Pilgrim Station reviewed General Electric Hitachi (GEH) 10 CFR 50.46 Notification Letters 2011-02 and 2011-03. These letters indicate that certain errors were discovered in the methodology application and inputs used by GEH for nuclear fuel core configurations with GE14 and GNF2 fuel, and when corrected may increase the Peak Cladding Temperature (PCT) limits in excess of 2200 degrees F under Loss of Coolant Accident (LOCA) conditions. Pilgrim's core contains both GE14 and GNF2 fuel. 10 CFR 50.46 paragraph (b) defines the acceptance criteria for the LOCA analysis process. The Pilgrim licensing basis PCT is evaluated for compliance with the criterion 50.46(b)(1) and must not exceed a PCT of 2200?F. GEH had provided a compensatory measure in the form of multiplier to be applied to the MAPLHGR (Maximum Average Planar Linear Heat Generation Rate) limit so that Pilgrim operates within 50.46 limits. Entergy/Pilgrim implemented the compensatory measure and as a result the errors reported have no impact on current plant operation or public health and safety. This 8-hour notification is being reported for conservative purposes in accordance with 10 CFR 50.72 (b)(3)(ii)(B). Based on 50.46(a)(3)(ii) criteria, Entergy/Pilgrim will submit a report within 30 days. Entergy/Pilgrim has notified the NRC Senior Resident Inspector." The licensee also plans to notify the State of Massachusetts. | Emergency Core Cooling System |