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News

The Fermi 2 radiological team was stuck between a rock and a hot spot.

At the plant’s radwaste facility, the team uses a crane with a grapple to move containers, which are about 5 ½ feet tall by 5 feet in diameter and weigh between 5,000 pounds and 10,000 pounds each. The liners are filled with spent resin which was used for filtering feedwater and other auxiliary clean-up systems.

In this case, the grapple used to move the liners wouldn’t release the container.

“It just wouldn’t let go of it,” Bryan Weber, principal technical specialist for Fermi 2’s Radiation Protection department, said. The team uses a remote panel to control the crane and grapple. “It is remote for a reason: because of the dose rates, you don’t want to get up close and personal with these containers.”

Dose rates near the container were about 74 Rem per hour. To put that in perspective, the administrative limit for a worker at Fermi 2, a member of the Utilities Service Alliance, is 1 Rem per year.

With the grapple not functioning, the crane could not be used, which significantly decreased the team’s ability to continue to process the spent resin.

“We had to go through quite the effort to come up with an alternative processing system to keep the plant online,” Weber said.

So Weber and his team looked to fix the situation. After trying a series of electrical overrides that failed to release the grapple on the liner, the team sought out vendors for help. After asking around, the team located one vendor that could provide a tool to rent for $200,000. That’s a big number to use a tool for one project.

Weber said after discussing it with senior management, Plant Manager Mike Philippon suggested asking a machine shop at DTE Energy’s technical service center, a support organization for the company.

It proved worthwhile — but not simple.

Thomas Grant, supervisor of the machine shop, said “it was quite a process to develop the prototype.” He said the team used Continuous Improvement tools such as rapid experimentation and Practice, Repeat, Train in the process.

“We always like a challenge,” he said.

After learning of the details, the team conducted a brainstorming session on different options — cutting the grapple off, for instance, or using a pillow-like hydraulic machine to push the grapple apart. He said Gary Dombrowski and Robert Cutsinger took the lead in the project.

But after considering and rejecting several ideas, the team settled on using hydraulics cylinders to push and break apart the grapple. They settled on using four, 10-ton hydraulic cylinders to do the job.

The idea for the tool was this: lower it down onto the grapple, tilt it slightly to fit into a small opening and then expand out by 15 inches to force the grapple apart, freeing the liner.

And it worked.

The team developed a wood prototype of the tools to make it easier to modify. After that was settled, the team machined the tool out of metal, built the hydraulic system and readied the equipment for use.

“It was quite an effort that was pretty intense,” Grant said. “But our guys, they were going to make sure this was going to succeed.”

In fact, the team developed a Just-In-Time training module to teach workers how to properly use the tool.

“They put quite a bit of effort into it,” Weber said.

“This is what I found amazing: they fit a 9-inch tool into a 7-inch slot. Seriously, that is what they did,” he said. “Not only was it fitting a square peg into a round hole, it was an extra big peg into a small hole.

“It was, in my opinion, genius on their part.”

In all, the cost for the tool was about $20,000 — saving the company about $180,000.

The grapple tool developed by Fermi.