LER: Pilgrim Juno Scram and LOOP

Originally posted on 4/24...reported. This is closely related to today's LER 2015-02-00... 

Basically these are arbitrary points...why didn't they interact with pilgrim before this.

Should have had big violations seen in the 2013 LOOP:should have had special inspection over these.

Over the leaking Safety Relief Valves 

the 2013 LOOP

The difference between the 2013 LOOP and 2015 LOOP is the magnitude of equipment problems(HPCI, core spray and the SRVs). 

Remember I contend, as Vermont Yankee was collapsing into permanent shutdown, the agency was pulling their punches with Pilgrim. They were afraid Pilgrim would end up like Vermont Yankee... 

"Based on the update of data following the third quarter of 2013, Pilgrim saw its performance indicator for Unplanned Scrams (shutdowns) with Complications shift from green to white. This indicator tracks unplanned scrams that require additional operator actions and that are more risk significant than uncomplicated shutdowns. Subsequently, when 2013 fourth-quarter data was finalized, another indicator for the single-reactor plant also transitioned to white. That indicator covers Unplanned Scrams per 7,000 Hours of Operation and becomes white if a plant experiences more than three unplanned shutdowns during that period of time." 

Licensee Event Report 2015-001 -00

Loss of 345KV Power Resulting in Automatic Reactor Scram During Winter Storm Juno

1. FACILITY NAME 2. DOCKET NUMBER 3. PAGEPilgrim Nuclear Power Station 05000293 1 OF 64. TITLELoss of 345KV Power Resulting in Automatic Reactor Scram During Winter Storm Juno5. EVENT DATE 6. LER NUMBER 7. REPORT DATE 8. OTHER FACILITIES INVOLVEDMONTH DAY YEAR YEAR SEQUENTIAL REV DAY YEAR CITYNAME DOCKET NUMBERNUMBER NO. N/A N/A01 27 2015 1 20 1 ACIT NAME DOCKETN UMBER2015- 001 - 00 03 30 2 N/A9. OPERATING MODE 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply)H 20.2201(b) 20.2203(a)(3)(i) 50.73(a)(2)(i)(C) 50.73(a)(2)(vii)N H 20.2201(d) 20.2203(a)(3)(ii) 50.73(a)(2)(ii)(A) 50.73(a)(2)(viii)(A)H 20.2203(a)(1) E 20.2203(a)(4) 50.73(a)(2)(ii)(B) D 50.731a)(2)(viii)(g)20.2203(a)(2)(i) 50.36(c)(1)(i)(A) K 50.73(a)(2)(iii) [] 50.73(a)(2)(ix)(A)10. POWER LEVEL K 20.2203(a)(2)(ii) K] 50.36(c)(1)(ii)(A) [ 50.73(a)(2)(iv)(A) K] 50.73(a)(2)(x)K] 20.2203(a)(2)(iii) K 50.36(c)(2) K] 50.73(a)(2)(v)(A) E] 73.71(a)(4)52 E] 20.2203(a)(2)(iv) K] 50.46(a)(3)(ii) 50.73(a)(2)(v)(B) K] 73.71(a)(5)K] 20.2203(a)(2)(v) K] 50.73(a)(2)(i)(A) K 50.73(a)(2)(v)(C) K] OTHER20.2203(a)(2)(vi) Specify inA bstract betow or in 50.73(a)(2)(i)(B) 50.73(a)(2)(v)(D) NRC Form 366A12. LICENSEE CONTACT FOR THIS LERLICENSEE CONTACT TELEPHONE NUMBER (Include Area Code)Mr. Everett P. Perkins, Jr. - Regulatory Assurance Manager 508-830-832313. COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORTMANU- REPORTABLE MANU- REPORTABLECAUSE SYSTEM COMPONENT FACTURER TO EPIX CAUSE SYSTEM COMPONENT FACTURER TO EPIXB FK BU M- YRT B SB RV T020 YLD CMP A544 Y14. SUPPLEMENTAL REPORT EXPECTED 15. EXPECTED MONTH DAY YEARSUBMISSION D YES (If yes, complete 15. EXPECTED SUBMISSION DATE) NO DATEABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines)

On Tuesday January 27, 2015, at 0402 hours, while in the process of lowering reactor power, with the reactor in the RUN mode at 52 percent core thermal power, Pilgrim Nuclear Power Station (PNPS) experienced a loss of 345KV power resulting in a load reject and an automatic reactor scram. The loss of 345KV power was due to faults from flashovers in the PNPS switchyard. All control rods fully inserted. The Emergency Diesel Generators had been previously started and were powering safety-related buses A5 and A6. The plant stabilized in Hot Shutdown. At the time of the event a significant winter storm (Juno) was buffeting Southern New England.

I think the real root cause should be: we have plenty and multiple examples that of our switchyard wasn't designed for the climate, and we knowingly chose to ignore the great reduction in safety to the plant and surrounding people.   

The root cause of the event is that the design of the PNPS switchyard does not prevent flashover when impacted by certain weather conditions experienced during severe winter storms. A modification of the switchyard is planned to address the susceptibility of the PNPS switchyard to flashovers during severe winter storms.

This event posed no threat to public health and safety.

BACKGROUND

Pilgrim Station Nuclear Power Station (PNPS) is connected to the transmission lines through a 345KV ring bus located within the station's switchyard. The 345KV ring bus connects the output of the main transformer (GSU), the startup transformer (SUT), Line 355, and Line 342. There are four gas circuit breakers connecting PNPS's 345KV ring bus sections: ACB-1 02, ACB-1 03, ACB-104 and ACB-1 05.

The Line 355 bus connects PNPS to NSTAR (Eversource) Carver Station and is connected to ACB-102 and ACB-1 05. The Line 342 bus connects PNPS to the Canal Power Plant's Switchyard in Sandwich, MA and to Auburn Street Station Switchyard in Whitman, MA. The Canal Switchyard is owned and operated by NSTAR and Auburn Street Station Switchyard is owned and operated by National Grid. ACB-103 and ACB-104 connect the Line 342 bus to the SUT and GSU bus. The 345KV system is the PNPS preferred off-site power source via the SUT.

The 345KV ring bus design locates the power transmission lines such that a failure of any one line will not result in the loss of the other line. Specifically, with both transmission lines in service, a failure of either 345KV line will not result in a main generator trip, a SUT trip, or a failure of the other 345KV line. Either of the two 345KV lines is capable of carrying full station output and supplying station loads via the SUT.

The 345KV protective relay system is designed and coordinated to isolate system faults and minimize the impact to the overall transmission system. The protective systems are comprised of a primary and secondary protection scheme and are divided into four zones of protection.

*The main transformer bus (isolated by ACB-104 and ACB-105)  

*The SUT bus (isolated by ACB-102 and ACB-103)  

*Line 355 bus (isolated by ACB-102 and ACB-105 and Carver Station)  

*Line 342 bus (isolated by ACB-103 and ACB-104 and Auburn Street Station and Canal Station)

When ACB-104 and ACB-105 open, the main transformer is isolated from the 345KV transmission system thus resulting in a generator load reject event.

In addition to the preferred 345KV off-site power lines, PNPS has a secondary off-site power source, a 23KV line from NSTAR's Manomet Substation that provides power to a shutdown transformer (SDT).

During normal station start-ups and shutdowns, the station's 4160V demands are supplied by the SUT. Once the station main generator is synchronized to the 345KV transmission system, the station unit auxiliary transformer (UAT) supplies all station 4160V demands, with the SUT maintained in standby, ready to provide 4160V power if necessary.

In anticipation of a major snow storm impacting the site on January 26, 2015, Operations entered Procedure 2.1.37 (Coastal Storm Preparations). Procedure 2.1.42 (Operation During Severe Weather) and EN-FAP-EP- 010 (Severe Weather Response). During the storm on January 26-28, 2015, meteorological instruments at PNPS recorded sustained wind speeds between 37 and 61 mph with the wind direction predominantly from the ocean toward the switchyard.

EVENT DESCRIPTION:

On 1/25/15 with PNPS operating at 100 percent power, the National Weather Service (NWS) issued a blizzard warning for winter storm Juno. Wind speed of 40 mph sustained with 50 mph gusts and snow fall of more than two inches/hour were predicted. PNPS entered procedures 2.1.42, Operation During Severe Weather and 2.1.37, Coastal Storm Preparations and Actions, and started making preparations for storm arrival. Preparations were completed on 1/26/15. At 0132 hours on

First, they should have shutdown hours before this. But seeing they were not, they should have seen the light based on past events...they should have scrammed at this point. What didn't upper management advise this to the shift prior in the approach of the storm.  

1/27/15, the 345 KV Line 355 bus faulted (for the first of five times) whereupon Operations personnel commenced a reactor shutdown at 0134. The Emergency Diesel Generators (EDGs) were started and loaded with the safety related buses. Reactor Protection System (RPS) bus "A" was placed on the backup power supply. At 0235 hours, the Line 355 bus faulted for the final time at which time the Line 355 breakers at both Carver and PNPS were left tripped open. This configuration left PNPS with one transmission line connected to the grid.

Honestly these guys are so dangerous, it took from 01:32 to 04:20 for the plant to auto trip. It is dangerous to take a scram because equipment could fail...you manually scram before the auto scram. 

Was the Pilgrim CEO stationed at the plant during big blizzards like Millstones??? 

At 0402 hours with the reactor at 52 percent power, Line 342 faulted resulting in a trip of ACBs 103 and 104. This isolated PNPS from the grid causing a generator load reject and automatic reactor scram. All control rods were verified fully inserted. The non-safety related back-up diesel driven air compressor, K-1 17 failed to start on instrument air system low pressure. K-1 17 failure to

That is why I hate this non safety air compressors. They are not instrumented up. You ain't taking rounds and readings on the backup air compressors knowing the condition of the battery. If they would have been instrumented up, an alarm would have stayed lit in the control room. They didn't test the backup air compressor just before the storm arrived. They could have had it running just before the storm.

Pilgrim had issues with diesel smoke in the reactor building last Nor'easter...did it occur this time?  

start was due to a battery low voltage condition. Primary Containment Isolation System (PCIS) Group II - Sampling Systems, Group VI - Reactor Water Cleanup (RWCU) System and Reactor Building Isolation System (RBIS) isolations occurred as expected. Reactor water level was maintained by the Reactor Core Isolation Cooling (RCIC) system and reactor pressure was maintained by the High Pressure Coolant Injection (HPCI) System. Once normal reactor level and pressure were restored, operators commenced a depressurization to the cold condition. At 0641 a Non- Emergency Notification to the NRC of the RPS and safety system actuations was made. (EN 50769).

During the reactor vessel depressurization, the High Pressure Coolant Injection (HPCI) System was removed from service prior to reaching the low pressure automatic isolation setpoint (Approx. 80 psig). Shortly after

There goes HPIC and one wonders how reliable HPCI is?  But the reactor was almost cooled down.

system shutdown, the HPCI Gland Seal Condenser Blower Overload Alarm was received. The HPCI System was declared inoperable. At 1656 hours, a Non-Emergency Notification to the NRC of the HPCI System inoperability was made. (EN 50771) Subsequent analysis determined that the cause of the overload condition was due to the inability to remove water from the condenser with the HPCI pump discharge

Right, having in house supplied air compressors is the safest mode. It a big safety hole at many plants not having in house safety electricity for the air compressors. Lots of plant get into big troubles without air compressor and it creates damaged.

You get it don't you, the back up air compressor not working was the cause of losing HPCI. This reflect very poorly with Pilgrim's operation and engineering not being able to anticipate this. It is very dangerous with having many components failing in a plant accident.  

How many other not working air valves didn't also work.

Was this not modeled in the computer simulators. I'd like to see how many LOOPs like this was thrown, practice in the simulator?  

piping isolated, since the air operated valves that would normally open to remove water were unavailable due to the loss of instrument air when K-1 17 failed to start. The analysis also determined that HPCI would have been available to perform pressure control or restore reactor water level if required. Upon opening of a valve in the HPCI discharge piping flow path, the HPCI Gland Seal Condenser Hotwell Pump would restore the condenser level to normal. The depressurization continued using Main Steam Safety Relief Valves (SRVs) for pressure decrease and Core Spray Loop "B" to maintain reactor vessel water inventory. When

So we know from the Part 21 the 3C Safety Relief Valve under went severe perturbation due bad components and severely damaged the valve.

The question left opened, did the 3C SRV valve have indications of seat leakage and how long did they know it? How were the long term trends on the SRV tail piece temperatures? Did any other SRV have elevated temperatures? 

Entergy says they don't put in the right resonance frequency to the purchase contract with these valves...some abnormal vibrations on the steam line destroyed the valve.The SRV valves weren't sturdy enough for the vibration duty. Many plant recently have come up with the same problem...

I think think the manufacturer is building these valves with poor quality components.      

SRV RV-203-3C was manually opened, the SRV did not appear to open or failed to open fully. Part 21 Event Report 50900 documents this condition. Post-event removal and disassembly of the valve revealed damaged parts in the main stage assembly. Further investigation by the valve manufacturer is required to determine the cause. Core Spray Loop "A" discharge header low pressure alarm

Now we know another independent system was impaired...the A Core Spray was dead. It is implausible the B wasn't dead also.  

was received due to the unavailability of the nonsafety related keep-fill system due to the loss of power to the non-safety related buses. Operators recognized the potential for voiding within the piping. To preclude the potential for damage of the piping due to water hammer pressure pulses, the Core Spray Loop "A" was not used during this event. At 1626 hours, Residual Heat Removal (RHR) Loop "B" was placed in service in the shutdown cooling mode. At 1658 hours, the reactor moderator temperature was less than 212 degrees F. Prior to restoration of offsite power to the switchyard, the switchyard bus insulators and bushings were cleaned of snow and salt contamination to prevent further flashovers.

Basically from 4 am to 5 pm the main lines wasn't   available...13 hours LOOP. 

On January 29, 2015 at 1643 hours, the loss of 345KV power condition was cleared when offsite power was restored to the switchyard and the startup transformer.  CAUSE OF THE EVENT The design of the PNPS switchyard does not prevent flashover when impacted by certain weather conditions experienced during severe winter storms. CONTRIBUTING CAUSES: Previous corrective actions to preclude recurrence taken in response to LER 2008-006-00, Automatic Scram Resulting From Switchyard Breaker Fault During Winter Storm, LER 2008-007-00, Momentary Loss of all 345kv Off-Site Power to the Startup Transformer from Switchyard Breaker Fault, and LER 2013-001-00, Loss of Offsite Power and Reactor Scram, did not prevent recurrence. Previous cause analyses of loss of 345KV transmission lines failed to fully analyze all available weather related data to understand precisely what weather related attributes (and characteristics) were necessary to guide operators in making decisions to maneuver the plant to shutdown prior to or during snow storms with the potential for creating flashovers. As a result, Procedure 2.1.42 failed to guide operators to the correct actions necessary to preclude the automatic scram during winter storm Juno. Previous cause analyses did not effectively use repeat

Does anyone believe this. Like to have all the data on winter storms...how many alarms on the main lines don't cause line or plant trips? I bet they got a lot of alarms and no plant trips on winter storms Effectively they were intentionally betting there would be no plant trip. Double or nothing every blizzard.

2008 blizzard LOOP-Corrective actions planned include the following:

- Review of potential design changes to improve switchyard resistance to weather related flashovers.

- Modify and replace the input breakers on the X55 and X56 transformers.

- Complete vendor evaluation of transformer tap control board failure.

events to evaluate design aspects to effectively communicate the risk of the current design.

CORRECTIVE ACTIONS 

The switchyard insulators and bushings were cleaned prior to return of the switchyard to service. The following corrective actions are planned to correct / preclude recurrence:

* Implement a switchyard design change to minimize switchyard flashovers during snow storms

    * Revise procedure PNPS 2.1.42 to provide additional       guidance including the requirement to place the           reactor in cold shutdown prior to the anticipated         arrival of certain severe winter storms

Additional corrective actions are captured in the corrective action program in Condition Report CR-PNP- 00558.
 
The Loss of Coolant Accident (LOCA) design basis accident (DBA) analyzed in the Updated Final Safety Analysis Report (UFSAR) assumes coincident loss of both 345 KV and 23 KV (preferred and secondary) sources (LOOP). The design imposes a 10 second delay in re-energizing the 4160V Emergency Buses required to mitigate the DBA to allow the EDG to start and reach voltage. This delay also allows the operating motors to coast down to a stop to prevent being repowered out of phase. In cases where coincident loss of an EDG presents a bounding condition, the affected safety bus is not assumed to be picked up by the shutdown transformer (SDT). The bounding condition in which all off-site power and onsite AC (EDGs) sources would be lost is a Station Blackout (SBO) transient event (10 CFR 50.63). PNPS is designed to recover from the SBO event by having a separate SBO diesel generator capable

What are the chances the standby SBO diesel generator would have had a dead battery just like the backup DG air compressors. They ain't just pushing a button on this guy like they would in the control room. That is why a real operator would think the whole flex philosophy in bankrupt. You think they would cleanly put the one diesel generator on the safety bus. I doubt it. Minimum certainty is all the crews in training actually starting up the DG and they putting it on the bus themselves repetitively like they know the back of their hand. How long would it take to get cooling to the core through a backup diesel generator?

You got any proof with ECCS automatic timing starts and the rest, the start-up DG could take this kind of sequence???

Think of the political and public ramifications locally and nationwide in a historic blizzard, if a nuclear plant didn't have any electricity for three or four hours. They bungled the start-up of the back up diesel generator or caused a fire in the plant over electrical shorts I doubt Pilgrim would ever start up again. 

of providing power to the required safety buses to shutdown the plant and maintain it in a safe condition. Thus, the loss of 345KV power experienced by PNPS is within the analyzed conditions. During the event, the EDGs, RHR, Core Spray Loop "B",

How can they say this, the gland seal was dead because the back up compressor didn't start and no motive force to drain the HPCI gland exhauster to the condenser. Then one side of the CS wasn't pressurized.

HPCI, and RCIC were available. These systems provided capability to supply makeup water to the vessel and ensured adequate core cooling was maintained. During and following the storm, operators were able to maintain safe shutdown conditions (reactivity control, reactor water inventory, decay heat removal, etc.). While loss of power to non-safety related spent fuel pool

This is so unprofessional losing cooling to the Fuel Pool... 

cooling was a key consideration, time-to-boil never became an overriding concern with respect to reenergizing buses and there was no recently irradiated spent fuel in the pool. The most recent recently irradiated fuel was almost 21 months old, and the time to boil was approximately seven days upon loss of fuel pool cooling. The spent fuel pool temperature remained less than 105 degrees F. The Emergency Diesel Generators were started and loaded with the safety related buses prior to the loss of 345KV power. The amount of fuel onsite initially was sufficient to operate the EDGs for 7 days (under LOCA conditions) and the SBO DG was always available. Throughout these events there was no adverse impact on the public health or safety. REPORTABILITY This report is submitted in accordance with: * 10CFR50.73(a)(2)(iv)(A)- System Actuation,
 * 1OCFR50.73(a)(2)(v)(B) and 1OCFR50.73(a)(2)(v)(D) - Event or Condition that Could Have Prevented Fulfillment of a Safety Function.
 The Reactor Protection System, Containment Isolation System, High Pressure Coolant Injection System, and Low Pressure Core Spray System are included in 10CFR50.73(a)(2)(iv)(B). The Reactor Protection System and Containment Isolation System automatically actuated. The High Pressure Coolant Injection System and Low Pressure Core Spray System were manually actuated. Since High Pressure Coolant Injection System is a single train system to fulfill a safety function, the inoperability was reported in accordance 1 OCFR50.73(a)(2)(v)(B) and 1 OCFR50.73(a)(2)(v)(D). PREVIOUS EVENTS The most recent loss of 345KV power events at PNPS reported as LERs are as follows:

The most recent loss, because the whole list of LOOPs over plant life would be so embarrassing. They were actively not looking events that would show the switchyard wasn't designed for the climate. No doubt you'd never get any pilgrim employee to admit that.  

LER 2008-006-00, Automatic Scram Resulting from Switchyard Breaker Fault During Winter Storm, dated February 12, 2009. LER 2008-007-00, Momentary Loss of all 345KV Off-Site Power to the Startup Transformer from Switchyard Breaker Fault, dated February 12, 2009. LER 2013-001-00, Loss of Offsite Power and Reactor Scram due to Winter Storm Nemo, dated April 4, 2013. ENERGY INDUSTRY IDEBTIFICATION SYSTEM (EIIS) CODES COMPONENTS CODESSwitchyard Bus BURelief Valve RVCompressor CMP SYSTEMSSwitchyard System FKMain Steam System SBHigh Pressure Coolant Injection System BJ\Low Pressure Core Spray System BMInstrument Air System LDESF Actuations (RPS,PCIS, RBIS) JE
 REFERENCES Condition Report CR-PNP-2015-0558, Loss of Offsite Power and Reactor Scram Condition Report CR-PNP-2015-0559 - K1 17 air compressor failed to start following unit scram. Condition Report CR-PNP-2015-0561 - SRV-3C appears to have not opened fully during manual operation.Condition Report CR-PNP-2015-0563, HPCI Overload alarm received during HPCI operation - Observed water emitting from P-223, Gland Seal Condenser Blower