Semantic search
| Entered date | Event description | |
|---|---|---|
| ENS 54524 | 13 February 2020 17:17:00 | On February 13, 2020, at 1025 hours (PST), during the performance of the quarterly control rod exercise surveillance test, Shutdown Bank 'B' Group 1 became misaligned greater than 12 steps from its group demand position. In accordance with Technical Specification 3.1.4, 'Rod Group Alignment Limits,' Action D, a Unit 2 shutdown to Mode 3 was commenced at 1233 hours. Investigation into the cause of the rod bank misalignment is in progress. There is no impact to the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified. |
| ENS 48395 | 10 October 2012 00:32:00 | On 10/9/12, at 16:30 PDT control room operators were questioned whether recently identified fire protection program deficiencies should have been reported to the NRC. On October 3 and October 8, 2012, DCPP (Diablo Canyon Power Plant) staff reviewing NFPA 805 Nuclear Safety Capability Assessment (NSCA) Variance From Deterministic Requirements (VFDRs) identified fire areas that neither conformed to Appendix R requirements nor had established, proceduralized and practiced compensatory measures in place. The issues were identified in the DCPP corrective action program and compensatory measures were established in accordance with the DCPP fire protection program requirements. Event: 10/3/12 Fire areas containing cables associated with startup transformers 1-2 and 2-2 could result in loss of startup power and also prevent the emergency diesels from performing their Appendix R safe shutdown function. Event: 10/8/12 Fire areas containing reactor coolant pump (RCP) breakers could result in loss of RCP seal cooling and prevent the credited local manual trip of the RCPs, contrary to the specified method of performing the Appendix R safe shutdown function. Event: 10/8/12 Fire areas containing cables for the ventilation systems of the 480V switchgear, DC panels, and battery chargers could require unproceduralized use of portable fans to maintain adequate cooling of the electrical equipment necessary to perform the Appendix R safe shutdown function. Operators established fire watches as compensatory measures as required by the DCPP fire protection program requirements. The above late notification of discovery of the unanalyzed conditions has been entered into the DCPP corrective action program. NRC Resident Inspector has been notified.
This is an update to EN #48395 reported on October 10, 2012, at 0032 EDT. During the NRC's Fire Protection Triennial Inspection the NRC identified that several Alternate Compensatory Measures (ACMs) were not in the current post-fire procedure CP M-10. The ACMs address potential Appendix R non-conformance issues identified via the initiative to convert the DCPP fire protection program to NFPA 805. PG&E has established compensatory measures for all the identified areas in accordance with the DCPP fire protection program requirements. (The) NRC Resident Inspector has been notified. Notified R4DO (Deese).
This is an update to EN #48395 reported on October 9, 2012, at 2132 PST. During the ongoing evaluation of the issues previously identified in this event notification, PG&E (Pacific Gas & Electric) has concluded that a fire in the fire areas containing cables associated with startup transformers 1-2 and 2-2 would not result in loss of startup power or prevent the emergency diesels from performing their Appendix R safe shutdown function. This issue was reported as an unanalyzed condition. However, it is analyzed and controlled in plant procedure CP M-10, 'Fire Protection of Safe Shutdown Equipment.' PG&E retracts the initial event documented on October 3, 2012, thus making the date on which the first unanalyzed condition was discovered October 8, 2012. Therefore, PG&E will submit the 60-day Licensee Event Report by December 7, 2012. The NRC Resident Inspector has been notified. Notified the R4DO(Whitten).
This is an update to EN #48395 reported on October 9, 2012, at 2132 PDT. On October 31, 2012, at 2128 PDT, PG&E provided an update to this event notification identifying that several alternate compensatory measures (ACMs) were not in plant procedure, CP M-10, 'Fire Protection of Safe Shutdown Equipment.' PG&E has evaluated this further and concluded that ACMs had been adequately implemented in CP M-10, and therefore retracts the EN update of (November 1, 2012 at 0028 EDT). NRC resident inspector has been notified. Notified R4DO (Walker). |
| ENS 45754 | 9 March 2010 23:39:00 | While attempting to analyze the consequences of scenarios (loss of coolant accident (LOCA) and loss of offsite power (LOOP)) postulated during the Component Design Basis Inspection (CDBI), PG&E concluded both units were in an Unanalyzed Condition that significantly degrades plant safety, and therefore, reportable under 10 CFR 50.72(b)(3)(ii)(B). The postulated scenario could result in permanently connected class 1E pump motors tripping over current relays due to sustained degraded voltage on the startup offsite power source. The scenario starts with a safety injection (SI) signal transferring 4160 volt vital buses from auxiliary power to the startup offsite power source. Following bus transfer, the startup source is postulated to degrade to a level above the first level under voltage relay (FLUR) setting of equal to or greater than 2583 volts and below the second level under voltage relay (SLUR) setting of equal to or greater than 3785 volts. Permanently connected class 1E pump motors would experience this degraded voltage for up to the SLUR time delay relay setting of equal to or less than 20 seconds. Prior to reaching the SLUR time delay relay setpoint and transferring loads to the onsite emergency diesel generators (EDGs), operating motors (e.g. auxiliary saltwater (ASW) pump and component cooling water (CCW) pumps) could trip on over current. Operators would be directed by procedures to re-start these motors on an operable power source (EDG). However, since this scenario has not been previously analyzed and could reasonably challenge containment pressure or peak clad temperature limits, it is considered unanalyzed. The postulated scenario had previously been considered non-credible, and therefore, had not been analyzed. PG&E considers this a nonconservative technical specification (TS) since the values in TS surveillance requirement (SR) 3.3.5.3 would not protect permanently connected class 1E loads from damage during degraded voltage conditions." The licensee has notified the NRC Resident Inspector. The condition was discovered by NRC inspectors while performing a CDBI inspection. |
| ENS 44588 | 22 October 2008 01:44:00 | On October 21, 2008, with both units operating at 100% power, Operators manually actuated the Unit 2 reactor protection system (RPS/reactor trip) due to high differential pressure (DP) across the circulating water pumps' intake traveling screens. The high DP resulted from a rapid influx of jellyfish. All systems responded as designed. All control rods fully inserted. Auxiliary feedwater actuated as designed. The grid is stable with power being supplied by 230 Kv startup power. Diesel generator (DG) 2-2 and 2-3 are operable in standby. DG 2-1 is inoperable due to scheduled maintenance. The traveling screens for the safety-related auxiliary saltwater system (ASW) are not degraded and are managing the influx of jellyfish with no significantly elevated DP. Unit 2 is stable in Mode 3 at normal operating temperature and pressure. This event is being reported in accordance with 10 CFR 50.72(b)(2)(iv)(B), 'RPS actuation,' and 50.72(b)(3)(iv)(A), 'Specified System Actuation.' Operators reduced power on Unit 1 in response to the potential loss of normal flow to the condenser due to the jellyfish influx on the traveling screens. Currently, the traveling screens are maintaining DP within limits and the unit is stable at 50% power. Unit 2 decay heat removal is being performed by Auxiliary Feed Water to four steam generators blowing down via the 10% steam dumps to atmosphere. No other safety related equipment was out of service at the time of the trip. The licensee notified the NRC Resident Inspector.
The licensee issued a press release regarding this issue. Notified R4DO (Deese). |
| ENS 42778 | 15 August 2006 18:21:00 | The following is being reported in accordance with the Diablo Canyon Power Plant (DCPP) Environmental Protection Plan (EPP) section 4.1 as an 'unusual or important environmental event' requiring NRC notification within 24-hours: During diving operations to clean the intake bar racks, the diver discovered 50 to 100 dead Cormorants. Cormorants are diving sea birds and are common in the DCPP intake cove. They have recently started nesting in larger numbers on a large rock at the southern end of the intake cove, and feed in the intake cove. The event did not impact plant operations. It is believed that the birds died of natural causes and collected on the bar racks due to the water currents. To help determine the cause of death, some birds are being saved for testing and analysis. DCPP will submit a written report within 30 days in accordance with section 5.4.2 of the EPP. The licensee notified the NRC Resident Inspector. |