Crews at Fermi 2 will complete this month the installation of two 23-foot long probes in the used fuel pool that will improve the plant’s ability to monitor water level during a loss of power.

Fermi 2 is the third Utilities Service Alliance fleet member to install the probes. The USA fleet is using MOHR Test and Measurement devices for the project. The contract between MOHR and the USA fleet allows each plant to save money and streamline the technical design aspects.

The project is part of the nuclear industry’s response to the events at Fukushima in Japan.

Randy Ebright, director of Fukushima Response for USA, said by leveraging the fleet, members have saved millions of dollars. He said, for example, that the fleet was able to split the cost of a failure modes and effects document.

The team is currently working on an agreement for long term technical support, spare parts and training of our plant staff. The commonality of our design will continue to reduce operational cost and limit spare parts stocking needs.

But most importantly, these new probes — which are also installed at Salem Unit 1 and D.C. Cook plants — will provide accurate spent fuel pool level measurement following a Beyond Design Bases External Event.

Going forward, direct reading of Spent Fuel Pool level instrumentation will also become a trigger for Emergency Action Level declaration as part of our Emergency Response plans

During the Fukushima event in 2011, the plants lost the ability to cool the spent fuel pools and plant operators couldn’t remotely determine how much water was in the pools. This was further complicated by the amount of debris that fell into the pools and the belief that the fuel pool liner integrity may have been compromised. This resulted in additional uncertainty, distraction and confusion during the event.

Ebright said the new pool probes can endure a beyond design-basis event.

“The probes are very accurate,” he said. “And they are a very rugged design. Qualification testing validated that these probes will continue to provide reliable, accurate indication following an event.”

The probes provide redundancy to plant operators. At Fermi, for instance, one probe is connected to an indicator in the Main Control Room. The second probe leads to an indicator on the second floor of the Reactor Building.

Probes measure the amount of water above the top of the fuel and allow operators to remotely monitor the level of the fuel pool. The probes use a technology called “guided wave radar sensors” where radar waves travel down and back up the probe to show the water level.

The probes can detect a change of a fraction of an inch in water level and can differentiate between liquid level of surface frothing or foaming, which might occur on the surface of the water during a seismic event.

Crews on the refuel floor at Fermi 2 prepare to install a water level probe in its used fuel pool.