The Defense Nuclear Facilities Safety Board has concerns about the safety attitude of employees and management at the Hanford vitrification plant, board Chairman Peter Winokur said at a congressional hearing this week.

"We will be identifying them for the energy secretary" in the near future, he said at a hearing about safety oversight of Department of Energy nuclear defense facilities before the House Armed Services Strategic Forces Subcommittee.

Winokur also outlined the three key safety issues at the plant that the board believes require prompt resolution.

The $12.2 billion plant is being built to turn much of the 53 million gallons of radioactive waste now held in underground tanks at Hanford into a stable glass form for disposal.

The board, which provides independent oversight of Hanford and other DOE defense sites, began an investigation of the vitrification plant's safety culture after Walt Tamosaitis, the former research and technology manager for the project, sent a letter in July. He believes he was dismissed from the project for raising concerns about future safe operations of the plant -- claims contractor Bechtel National denies.

"The board believed he was a credible individual who had played a major role in the project," Winokur said at the hearing.

It also wanted to make sure that it heard the full story and that witnesses freely could speak at a hearing held in Kennewick in October to gather information about technical issues related to safe operation of the plant.

"Subsequent to that, we've identified other issues," Winokur said.

The crux of a strong safety culture is an empowered work force, he said. People must be comfortable raising concerns to management and be confident the messenger will not be shot, he said.

In addition, safety culture is driven by leadership, so the board also has looked at that, he said.

"The Department of Energy has a strong history and culture of safety in working with unique nuclear hazards and facilities," Shari Davenport, a DOE spokeswoman, said after the hearing. "We stand by our safety record and the nuclear safety culture of the department."

The board has been concerned about the vit plant's system to keep wastes mixed and moving through the processing system. The high-level radioactive waste is so hazardous that there can be no human access to the mixing tanks during the 40 years the plant operates, so the mixers have been designed without moving parts that would require maintenance.

But if the mixing system is ineffective, flammable gas could accumulate in the tanks and solids could build up on the bottom of tanks, posing a hazard of a nuclear criticality occurring, Winokur said in the written testimony he submitted.

DOE agreed at the October hearing to conduct large-scale testing to make sure the mixing issue is resolved, and the board has sent its recommendations on what should be required in the testing, Winokur said.

"DOE is developing a plant to implement the recommendations now, but it is not yet clear whether the plan will be fully responsive to the board's concerns," according to Winokur's written testimony.

The second technical issue of safety concern is a new control strategy for flammable gas in the plant's processing systems. DOE for the first time has used a quantitative risk analysis as a design tool, but it has no standards for controlling the assumptions that underpin the analysis, according to the written testimony.

The board hopes to see validation of the methodology this month that will convince members hydrogen-related issues in pipes and vessels of the plant will be appropriately addressed, Winokur said. However, if the approach cannot be shown to be adequate, the board will want active safety controls re-established.

The final issue will take longer to resolve. The board is concerned about the ability of the Hanford tank farm to supply waste that is compatible with the vitrification plant. The plant's mixers have limited ability to control the amount and size of solid particles in the waste.

It's an ongoing issue that will be addressed during the next couple of years as the vitrification plant project refines what waste it can accept and the tank farms continue to adjust, Winokur said.

"We have identified a path forward for the remaining three technical issues that will assure the safe design, construction and operation of the (vitrification) plant," Davenport said. DOE is planning to start operating the plant in 2019.

* Annette Cary: 509-582-1533; acary@tricityherald.com; More Hanford news at hanfordnews.com.