The possibility of a serious problem once the Hanford vitrification plant begins operating weighs heavily on Energy Secretary Steven Chu, he said Friday during a visit with Hanford workers in Richland.

He is likely to assemble the sort of panel of brilliant and creative thinkers he brought together after the Fukushima, Japan, nuclear disaster and the Gulf oil spill, he said.

He might become personally involved, carving out a week to spend on the issue at Hanford with the project's engineers, he said.

Chu was in the Tri-Cities on Thursday afternoon and Friday morning to meet with small and large groups of Hanford employees to discuss the importance of safety. He told the Defense Nuclear Facilities Safety Board he would travel to the Tri-Cities and meet with Hanford workers after the defense board questioned the nuclear safety culture at the Hanford vitrification plant.

The visit included a question and answer session with about 500 employees Friday morning at Howard Amon Park in Richland.

One employee told Chu he had concerns about the vitrification plant, in part because of the lack of experienced nuclear manufacturing in the United States. People are working hard on the vit plant, but if something does go wrong after it starts operating, they would never forgive themselves, he said.

The plant will treat high-level radioactive waste left from the past production of weapons plutonium, and some areas are expected to be too radioactively hot for humans to enter after it begins operating.

The sort of review team Chu is considering assembling would include people he knows personally rather than experts in specifically related fields, including some of the people he called on after the Gulf oil spill and Fukushima nuclear disaster, he said.

They could spend a week looking in detail at the project "to see if anything was overlooked," possibly with Chu as part of the team, he said.

If something were to go wrong at the vit plant, DOE would need to limit the damage to prevent it from escalating and also would need to know how to recover the project, he said.

"All these things have to be thought of as we go forward," he said.

That the plant has to operate for 40 years and humans can not go in to fix problems "is a pretty scary proposition," he said.

Chu also said he has had extended conversations with people designing the mixing system for tanks of high-level waste within the plant.

The systems must keep particles of waste suspended in the mixture rather than settling out, but the mixing system and particles must not cause so much erosion that the system cannot operate for the 40 years needed.

Chu appeared to speak without notes before taking questions, talking about the nation's responsibility to clean up the Cold War legacy of radioactive and chemical contamination at Hanford and to do it safely.

"We need to protect the most important asset we have in DOE. That's our workers," he said.

The attitude toward safety has to come from leadership down the ranks, he told a laid-off employee at the event who asked how Chu can get his message that safety is important taken seriously.

As the former director of the Lawrence Berkeley National Laboratory in California, he once shut down the laboratory of a prominent scientist until safety violations had been fixed, which took three weeks.

Shelly Doss, who was laid off from Washington River Protection Solutions last fall after raising environmental issues, asked the question.

The contractor said after the meeting that she was one of 244 employees laid off then and that she was not selected because of environmental or safety issues she raised.

Dave Roberts told Chu he was concerned that so much work was being given to subcontractors with workers who might be more transient and less experienced than longtime contractor employees.

"These people do not have the same knowledge base," he said.

Issues of training had come up in a previous meeting during the energy secretary's visit and he planned to look into it, Chu said.

At a brief press conference after the meeting, Chu said he was "very concerned" about the anticipated increase in the cost of the vitrification plant and an anticipated longer schedule for completion. The last projected cost was $12.2 billion with a start of operations in 2019.

But cost and schedule cannot be the top priority, he said. The top priorities have to be keeping workers safe while it is built and a design that ensures a plant that can last as long as there is waste to treat and that works as intended, he said.

This was Chu's second visit to Hanford as energy secretary. He also visited in August 2009.