More On the Grand Gulf Scram on Dec 12, 2018

I wonder if the Dec 12, 2018 special inspection results are out? I doubt it.

So two hours after the event started, they are forced to scram. This is totally non conservative. God knows how bad reactor water level was jumping around. So all this hiring below comes from the Scram on Dec 12, 2018 and the deficiencies in plant operations throughout 2018. In this 2016 special inspection below, Entergy voluntarily shutdown to train their operations staff for five months. They brought in many industry experts to figure out what is wrong and retrain the licensed operator. Out of the 2018 scram hiring some 300 hundred employees Entergy is overhauling operations again. Why is this repetitive retraining and overhauling plant operations going on in the worst plant in the nation? Why can't the NRC ROP quickly turn around a bad actor plant in a fairly short time?      

2016 Special Inspection 

The Nuclear Regulatory Commission (NRC) has begun a special inspection at the Grand Gulf Nuclear Station in Mississippi to review circumstances surrounding several recent operational events. The Entergy plant has been shut down since September 8.

On September 23, following maintenance on the residual heat removal system, workers discovered that a misalignment of valves had rendered the plant’s alternate decay heat removal system unavailable. Technical specifications require that the alternate system be available when one of the plant’s two residual heat removal systems is out of service. The system is used to remove decay heat from the reactor following shutdown. The following day, when preparing to restart the reactor, control room operators caused an unexpected increase in reactor vessel water level due to a misalignment of valves.

Three NRC inspectors will spend about a week on site evaluating the cause of the problem and the adequacy of corrective actions to address performance issues. An inspection report documenting the team’s findings will be publicly available within 45 days of the end of the inspection.

“The purpose of this special inspection is to better understand the circumstances surrounding several recent operational events to determine if operator response was appropriate,” said NRC Region IV Administrator Kriss Kennedy. “We will also review the licensee’s corrective actions to ensure that their causes, including associated equipment problems and any contributing operator actions, have been effectively addressed.”  

Entergy hiring 320 for Mississippi nuclear operations 

Associated Press Published 8:29 a.m. CT Jan. 25, 2019 | Updated 9:10 a.m. CT Jan. 25, 2019 

New Orleans-based Entergy says it will add 250 jobs in Jackson, augmenting its nuclear workforce. Spokeswoman Mara Hartmann says some employees will transfer from northeastern nuclear plants Entergy is closing or selling.

The electrical utility says it's also hiring another 70 people at Grand Gulf, increasing workers to 890. Entergy is overhauling the plant's management after operational problems. Grand Gulf supplies electricity to customers in Mississippi, Arkansas and Louisiana...

Downtime at 'aging' Grand Gulf attracts increased scrutiny

Edward Klump and Kristi E. Swartz, E&E News reporters Energywire: Tuesday, December 4, 2018

Tucked near Mississippi's border with Louisiana, deep in Entergy Corp.'s territory, rests the largest single-unit U.S. nuclear power station.

It's called Grand Gulf, and it boasts a 1,443-megawatt capacity.

But it hasn't been acting like a dependable backbone of the power grid.

An E&E News review of federal daily reactor status reports from 2013 through last month found Grand Gulf listed at full power roughly 52.5 percent of the time. It was at zero percent power almost 21 percent of the days studied. On other days, it was at various reduced levels.

Does that sound like a baseload plant?

"No," said Ted Thomas, chairman of the Arkansas Public Service Commission.

New Orleans-based Entergy has a 90 percent stake in the plant through an entity called System Energy Resources Inc. Cooperative Energy in Mississippi has the other 10 percent...

They bungle this event below as a whole and control of reactor water level. It is not the first time they lost control of water level. You notice how components that feed the vessel (RCIC) are having mechanical issues delaying the control of water level.  

Licensee Event Report 2018-010-00, Reactor Manual Scram due to Main Turbine Bypass Valve Drifting Open 

Grand Gulf Nuclear Station (GGNS) Unit 1 was operating at approximately 100 percent power in Mode 1. There were no Structures, Systems, or Components that were inoperable that contributed to this event.
B. DESCRIPTION
At appoximately 1200 hours CDT on Wednesday, December 12, 2018 while operating in MODE 1 at appoximately 100 percent power the GGNS·Main Steam Bypass Stop and Control Valve 'A' [JI] began drifting open. The valve began to modulate between O -10% open over the course of 90 minutes. After 90

Can't you hear the CEO telling the licensed operators, "I don't want you shutting down for any reason". We are getting into a lot of outside trouble with our disgraceful capacity factor and gads of shutdowns. One more scam or down power and I am going to fire you all. I am exaggerating here a little, but I suspect this kind of upper level pressure with the two hour delay in fixing the B/P valves. The delay was the operators and other techs trying to troubleshoot to problem and hopefully going to fix the issues before the plant scram. And the indications was worsening by the seconds.  

minutes, the valve began to open at an increased rate, reaching approximately 50% open. The reactor was manually scrammed at 1351 hours. The Main Steam Line Isolation Valves [SB] were manually closed as a mitigating action to control reactor pressure vessel rate of depressurization and cooldown. Reactor pressure was controlled through the use of the Safety/Relief Valves [SB] and ultimately the Reactor Core Isolation Cooling (RCIC) System [BN].
During the scram recovery, at 1358 hours the operator proceeded into the steps for a controlled start of RCIC. The expected RCIC injection response was delayed due to discharge pressure indication and governor valve light indications were not as expected. Therefore, the operator prepared to initiate the High Pressure Core Spray (HPCS) System [BG] based on current reactor water level and its trend.
During preparation to initiate HPCS, the operator noted that RCIC had started to inject but reactor level was in the low end of the d~sired control band at-24.811 Wide Range (WR) with a downward trend and'current RCIC injection was not arresting the decreasing trend in a timely manner. After evaluating the reactor water level and rate of change, the operator completed manually starting H PCS injection at 1408 hours. At 1409 hours, the HPCS injection was secured with reactor water level at 7.4" WR and trending higher and RCIC still injecting. RCIC and Safety/Relief Valves were utilized for reactor water level control until RCIC was placed in standby at 1645 hours. 

As far as the delay to shutdown, there is nothing to fix on failed linear variable differential transformer below. I wonder how old it was? They can't operate for long with that kind of problem. The delay in scraming provided no benefit to prevent a scam or shutdown. They should have emediately scrammed and I suspect they were required to emediately shutdown per procedure. Not wait two hours to do the required thing...    

The direct cause of the event was a failed Linear Variable Differential Transformer (L VDT) in the actuator for the Main Steam Bypass Stop and Control Valve 'A' that directy resulted in the inability of the valve primary controller to properly position the valve. Failure of the L VDT resulted in a constant error signal being present at the controller, which allowed the valve to integrate open over time.