An Unforgettable Night - ATC Operator Event at Palisades

There are a lot of these CRDM seal shutdowns at Palisades. No other plant in the nation has these kinds on troubles. These complex seal repair shutdowns have been involved with unpredictable interactions and incidences.

A initial plant design defect that is not corrected is driving enormous complicity into the control room and their employees are being overwhelmed by it.

I told the NRC this was a very important event for the industry and there should have been reports to the industry about what went on this night a Palisades. What nobody can get away from, the agency doesn't have the capability to capture events in such detail as this employee did.

This event occurred on Oct 23, 2010 and Palisades has had another seal shutdown on Jan of this year. We got to see this letter for the first time this March 8 2012.

I believe the event was entered into the Palisades ROP as a question of why did one of their employees leave the control room. Nobody has yet answered why were they winging this vacuum fill procedure, why did they lose reactor water level for a period of time worrying about vortexing and why did they allow so many distraction going on while they were manipulating core water level during a high risk alignment of the plant.


An Unforgettable Night - ATC Operator Event at Palisades

Introduction
On the early morning of October 23, 2010, I left the ‘at the controls’ area of Palisades nuclear plant without a proper relief or turnover. Up until that time, I had always considered myself to be a very conscientious and safe operator. I never imagined that I would leave the control room without a proper turnover – but I did. I hope by writing this article, others can learn from my mistakes and avoid making the same or any similar mistake. With that objective, this article describes the events that led to my actions, the effect this event has had on me, the lessons I have learned, and my experiences with the NRC investigative and enforcement processes.

Description of Events
Palisades was nearing the end of a refueling outage, which was on course to be our most successful ever due to the short duration and large number of major projects completed. We were about to enter our third reduced inventory period to perform a vacuum fill operation.

This vacuum fill procedure was relatively new for Palisades, having successfully

performed it for the first time during the previous refueling outage. It is a procedure to lower the water level in the reactor to the middle of the hot leg, and then draw a vacuum on the Primary Coolant System (PCS) to evacuate air and other non-condensable gasses. We devised this procedure in an effort to improve plant reliability—specifically to extend the life of our control rod drive mechanism pressure boundary seals.

Excerpts:

During the brief, I mentioned that during my turnover briefing, I heard that the reactor head did not have a vent path.

We lined up the drain path and commenced, but the PCS level indications did not respond as expected and we stopped the drain.

During this period, we had Auxiliary (non-licensed) Operators (AO's) troubleshoot the problem by verifying level glass and vent path lineups.

Concurrent with the PCS drain, most of the control room staff was at the Infrequently Performed Test and Evolutions (IPTE) brief for the vacuum fill work.

While this occurred, we had more issues with the EHC system; a reactor operator called the control room and stated he was not sure we had a good EHC flow path.

I felt this was a problem that required reviewing the prints and was too distracting with the PCS drain taking place while in reduced inventory, so I handed off the call to a different operator.

I told a Senior Reactor Operator that we were having issues with the EHC system, but he was busy overseeing the PCS drain.

A few moments later, however, the EHC low level alarm came in.

Several minutes later, the low level alarm was still not clear and I was concerned about a possible leak, so I secured the pump. I quickly heard back that there was a spill...

Consequently, they requested that the pump be placed in service for their vendor work, stating the cooling and flow path issues were solved.

This was all happening while the PCS level indication troubleshooting was in progress.

Eventually, Maintenance workers removed some temporary flange covers on the reactor head for a better vent path.

The drain that we initially briefed to be about 17 minutes ended up taking over three hours.

After we got to mid-loop, I lowered shutdown cooling flow to about 3100 gpm, which was the high end of the vacuum fill requirements.

...commented that he did not like the pace I was making my adjustments.

The previous time we performed the vacuum fill procedure, it worked flawlessly, but this time was different.

There was indication of a leak somewhere that was intermittently venting and allowing pressures to equalize throughout the system.

While Operator 1 and other members of the control room staff were troubleshooting the problems with vacuum fill, we received the low critical service water alarms and entered a procedure for "Loss of Service Water."

...the Control Room Supervisor (CRS) had to come down off the CRS’ “island” and speak with me directly to ensure effective communications during this very active period in the control room.

We soon learned that the work control center sent out a lube and stroke PM for the main lube oil service water isolations, and that was probably the cause of the low header pressure.

During the hold, I noticed the shutdown cooling flow rate had slowly started to trend down to 2900 gpm on its own and I voiced my concerns to the Control Room Supervisor. I showed him the one minute shutdown cooling flow rate trend on the Palisades Plant Computer (PPC), and said there may be some vortexing or other flow phenomenon that I did not understand.

He stated we could also enter the LCO, if necessary.

Suddenly, however, PCS level indication sharply fell to an elevation below the bottom of the hot leg.

As PCS pressure rose, the primary coolant level slowly recovered to an expected value and I received the order to raise the PCS level to exit reduced inventory.

By this time, it was early morning and we exited reduced inventory during SRO turnover.