Problem at Kewaunee Triggers Alert

[mauner]

I was amazed to read that the Shift Manager declared an Alert. See Story link.

http://www.themilwaukeechannel.com/news/9040658/detail.html?rss=mil&psp=news

After reading NRC event numbers 42528 & 42530 on 4/27/06, I don't understand why an Alert would be declared.

If a turbine trip provides the signal to automatically shut down the reactor why would the absences of a turbine trip be considered a failure of the reactor protection system?

 

[jpankask]

The plant had lost both feedwater pumps while at 35% power. The loss of both feedwater pumps should have triggered a turbine trip, which in turn should have triggered a reactor trip. Operators had to manually trip the reactor. That was the failure of the reactor protection system.

 

[mauner]

I understand that a turbine trip should have tripped the reactor. But does a failure in a BOP trip equate to a failure of the Reactor Protection System?

I don't think that the reactor protection system "looks at" the feedwater pump logic. If the turbine stop valve position is used to initiate a reactor trip and the contacts failed to perform their function I agree that you have a failure of the reactor protection system. However, if the turbine didn't trip why would you expect the reactor to trip?

Had the reactor operator tripped the turbine manually and that caused a reactor trip, would it still have met the condition to declare an alert?

 

[jpankask]

The bottom line is that the plant was in a condition where the steam generators had the potential to lose capacity to remove heat from the primary coolant, and possibly expose the U-tubes. The reactor should have AUTOMATICALLY tripped, whatever the flowpath is to complete the actuation. I do not believe that a manual turbine trip would have cleared them from the alert because operator action was still required to perform a function that should have occurred automatically.