Summary of Pilgrim SCRAMS 2003-2015
The following is a work in progress; summary includes all SCRAM events between 2003-2015, and an incomplete list of non-SCRAM events from 2013-present. See also, this list of Pilgrim Events 1965-2013, compiled by Dave Lochbaum, Union of Concerned Scientists.
More Event Notification Reports can be found on the NRC website:
- August 22: SCRAM (Automatic) – REACTOR SCRAM DUE TO A SINGLE MSIV CLOSURE; “On Saturday, August 22, 2015, at 1628 [EDT], with the reactor at 100% core thermal power (CTP) the Pilgrim Nuclear Power Station (PNPS) experienced an automatic reactor scram signal due to the rapid closure of one main steam isolation valve (MSIV). Other than the MSIV all other plant systems responded as designed. Plant cool down is in progress using steam bypass to the main condenser.” (NRC Event # 51338)
- May 22: SCRAM (Manual) – MANUAL REACTOR SCRAM DUE TO LOSS OF CONDENSER VACUUM; “On Friday, May 22, 2015 at 1002 EDT, with the Reactor Mode Select Switch in the Start-Up position and the reactor at approximately 3 percent core thermal power, while returning to power from Refueling Outage Number 20, a manual reactor scram was inserted due to degrading main condenser vacuum.” (NRC Event # 51087)
- February 14: Preemptive Shutdown – Due to winter storm ‘Neptune.’ Not a true SCRAM, but this was a planned shut down due to an approaching intense winter storm.
- January 27: SCRAM (Automatic) – AUTOMATIC REACTOR SCRAM ON TURBINE TRIP DUE TO LOSS OF OFFSITE POWER; “On Tuesday January 27, 2015 at 0402 hours, with the Pilgrim Nuclear Power Station (PNPS) Reactor Mode Select Switch (RMSS) in Run and reactor power approximately 52% an automatic reactor scram signal was received due to the automatic trip of the main turbine that was initiated by the opening of the main generator breaker, ACB-104.” (due to winter storm ‘Juno’) (NRC Event # 50769)
- May 15 : Taken off-line to “perform necessary maintenance to address low-level equipment needs that could potentially challenge reliability for the remainder of the operating cycle.” – Entergy spokesperson
- December 4: Leaky steam valve. Reactor still down.
- October 14-21: Off-site power to plant unavailable because of NStar problem, which caused initial shutdown. Plant remained closed for two days after power restored because of faulty mechanical pressure regulator, which caused water levels in the nuclear reactor to become too high.
- October 14: SCRAM (Automatic) – REACTOR SCRAM AND START OF EMERGENCY DIESELS DUE TO PARTIAL LOSS OF OFFSITE POWER; “On Monday October 14, 2013 at 2121 hours [EDT], with the reactor critical at 100% core thermal power, the mode switch in RUN, and offsite power 345kV line 342 out of service for scheduled modification, a loss of offsite power occurred due to the loss of the second 345kV line 355.” (power line out of service) (NRC Event # 49441)
- September 8-17: Steam pipe leak. (Plant restarted on August 26, but did not reach full power before leak occurs.)
- August 22-26: Electrical problems cause all three main water pumps shut down.
- August 22: SCRAM (Automatic) – REACTOR PROTECTION ACTUATION (SCRAM); “On Thursday, August 22, 2013 at 0755 hours [EDT], with the reactor critical at approximately 98% core thermal power, and the mode switch in RUN, a manual reactor scram was inserted due to lowering reactor water level. The cause of the lowering reactor water level was due to the trip of all three Feedwater Pumps.” (NRC Event # 49296)
- April 18 – June 3: Scheduled refueling.
- April 14: SCRAM (Manual) – SPECIFIED SYSTEM ACTUATIONS WHILE SHUTTING DOWN; “On Sunday, April 14, 2013 at 2217 hours, with the Pilgrim Nuclear Power Station (PNPS) Reactor Mode Select Switch (RMSS) in Start-up, the turbine generator previously removed from service, and the reactor sub-critical on Intermediate Range Monitors Range 2 and lowering, a manual reactor scram was inserted due to reactor pressure lowering beyond established control bands.” (NRC # 48923)
- February 8-16: Winter storm causes offsite power loss and main generator load reject; 169 hours down.
- February 8: SCRAM (Automatic) – The reactor automatically scrammed at 9:17 pm when a blizzard caused offsite power to be lost. UNUSUAL EVENT DECLARED DUE TO LOSS OF OFFSITE POWER; “Pilgrim Station scrammed on a loss of offsite power. All systems performed as designed. Groups I, II, VI went to completion. Reactor Core Isolation Cooling (RCIC) is injecting to the vessel controlling level. High Pressure Coolant Injection is in pressure control and slowly cooling down. Offsite power was lost multiple times. The Startup Transformer has been declared inoperable. The Unusual Event was declared under EAL SU 1.1 based on loss of offsite power greater than 15 minutes [at 2200 EST].” (due to winter storm ‘Nemo’) (NRC Event # 48736)
- January 20-24: Leaking safety valve.
- January 10-17: Both recirculation pumps tripped, followed by a head drain valve leak.
- January 10: SCRAM (Manual) – The operators manually scrammed the reactor per procedures after both recirculation pumps tripped while an instrumentation and control surveillance test was being performed. REACTOR PROTECTION ACTUATION (SCRAM) – RECIRCULATION PUMP TRIP; “On Thursday, January 10, 2013 at 1534 hour [EST], with the reactor at 100% core thermal power, both recirculation pumps spuriously tripped and a manual reactor scram was inserted as required by station procedures.” (NRC Event # 48664)
- May 22: SCRAM (Manual) – Operators manually scrammed the reactor from 35% power at 1:11 pm due to increasing condenser pressure. The operators began reducing the reactor power at 4:08 am for a scheduled thermal backwash of the condenser. During the backwashing, condenser vacuum began to be lost. MANUAL REACTOR SCRAM DUE TO DEGRADING CONDENSER VACUUM; “On Tuesday, May 22, 2012 at 1311 hours [EDT], with the reactor at approximately 35% core thermal power, during a planned power reduction to support thermal backwash of the main condenser, a manual reactor scram was inserted due to degrading main condenser vacuum.” (NRC Event # 47945)
- May 10: SCRAM (Automatic) – Reactor automatically scrammed on high-high flux on the intermediate range monitors during startup. REACTOR PROTECTION SYSTEM ACTUATION DURING START-UP; “At 1315 hours on Tuesday, May 10, 2011, with the Reactor Mode Select Switch in Startup, the Reactor Protection System (RPS) actuated due to a valid Hi-Hi trip signal from the Intermediate Range Monitors (IRMs) of the Neutron Monitoring System. At the time of the RPS actuation, reactor thermal power was four (4)% and control rods were being withdrawn as part of a planned reactor startup from a refueling outage. The RPS actuation signal resulted in a reactor scram. The IRMs were in range 7 when the scram occurred.” (NRC Event # 46837)
- December 19: SCRAM (Automatic) – Reactor automatically scrammed when a winter storm caused icing in the main switchyard. AUTOMATIC REACTOR SCRAM DUE TO LOAD REJECT; “On December 19, 2008, at 1831 hours with the reactor at 100% core thermal power (CTP) an automatic reactor scram occurred. It appears the scram occurred as a result of a load reject experienced during a severe winter storm. Three of the four safety relief valves opened in response to the event. Primary Containment Isolation System (PCIS) Group 2 (sample valves) and Group 6 (reactor water cleanup system) and the reactor building isolation system (RBIS-secondary containment) isolated as designed (all have since been restored) on the reactor water level +12 inches setpoint due to normal vessel shrink. Initial review indicates all safety-related systems responded as designed. Off-site power has been maintained; however the two 4kv safety related buses (A5&A6) were conservatively placed on the station emergency diesel generators due to potential grid stability concern.” (NRC Event # 44735)
- March 17: SCRAM (?) – Operators manually scrammed the reactor at 4:55 pm due to an increasing trend in unidentified drywell leakage. Workers identified the source to be packing leakage from reactor water cleanup (RWCU) system inlet valve MO-1201-85; GROUP ISOLATIONS FOLLOWING MANUAL REACTOR SCRAM; “On March 17 2007, at approximately 1658 EDT, Group 2 (Reactor Building Ventilation Isolation) and Group 6 (RWCU Isolation) automatic containment isolation signals were received due to low reactor water level following the insertion of a manual scram signal. The manual scram signal was inserted following the reaching of internal administrative limits on changes in unidentified drywell leakage. The receipt of these isolation signals is not unusual following the insertion of a scram signal. The reactor was manually shutdown due to reaching internal administrative limits on changes in unidentified drywell leakage.” (NRC Event # 43245)
- March 13: SCRAM (Manual) – Operators manually scrammed the reactor at 6:08 pm due to increasing temperature in the augmented offgas system recombiner caused by failure of the pressure control valve supplying steam to the recombiner; MANUAL REACTOR SCRAM AFTER OFFGAS SYSTEM FAILURE; “During a power ascension, the non-safety Augmented Offgas System experienced a failure which caused a Recombiner high temperature condition. To protect components of the non-safety Augmented Offgas System, station procedures require a manual scram of the reactor when this condition occurs. Station procedures were followed and the reactor was manually scrammed at 18:08.” (NRC Event # 42414)
- May 19: SCRAM (Automatic) – Reactor automatically scrammed due to spurious operation of the turbine bypass valves; AUTOMATIC REACTOR SCRAM RESULTING IN PRIMARY CONTAINMENT AND REACTOR BUILDING ISOLATIONS; “At 0424 EDT, during startup operations, the Main Turbine Bypass valves unexpectedly opened and depressurized the reactor vessel. After depressurization, the reactor level increased due to swell and caused an automatic reactor scram. Additionally, there was a Reactor Building Isolation Signal and Group I, II, and VI Primary Containment Isolation Signal generated. Immediately after the automatic scram, five control rods failed to insert into the core. Plant operations personnel performed actions in accordance with their Emergency Operating Procedures to drive the control rods into the core.” (NRC Event # 39857)
Sources: NRC website and Entergy press releases, Cape Cod Online.