MOX structural welds not up to code, report says

A new inspection report released this week shows that safety-related welds at a Savannah River Site factory being built to convert weapons-grade plutonium into mixed-oxide fuel failed to meet industry code, causing some concern about the level of rework required for the $7.7 billion project.

 

According to an Oct. 29 report from the U.S. Nuclear Regulatory Commission, federal inspectors found the MOX project at SRS inadequately translated welding measurements into design documents to ensure compliance with standards outlined by the American Welding Society.

The organization requires welding of safety-related structural steel that is thicker than three-quarters of an inch to have a minimum weld size of five-sixteenths of an inch. The NRC found structural steel supports for MOX’s Ground and Sorted Pellet Storage Unit Glovebox and associated shield panels were installed with a weld size of a quarter-inch.

The finding was determined to be a Level 4 violation, the lowest NRC can give. But industry watchdogs believe the inspection provides another indication that a large amount of “rework” needs to be done for the facility that’s being built to satisfy a 2000 treaty the U.S. signed with Russia to dispose of 34 metric tons of surplus plutonium.

“This inspection report may be the tip of the iceberg,” said Edwin Lyman, a senior scientist with the Union of Concerned Scientists based in Washington. “It really provides some context to what we have been hearing of problems in general at the plant.”

The project’s contractor, CB&I Areva, originally estimated a 2.5 percent rework rate for MOX, but during a hearing last month before the House Armed Services Committee, John MacWilliams, senior adviser to U.S. Energy Secretary Ernest Moniz, said that the rate is about 25 percent at this point.

Kelly Trice, president of CB&I Power, wrote an Oct. 9 letter to committee member Rep. Joe Wilson, R-S.C., to “set the record straight on some issues that were discussed at the congressional hearing,” including the rework rate.

Trice said the main MOX facility that CB&I AREVA MOX Services is constructing has a rework rate less than typical for large projects. According to industry studies, on a typical project, rework costs between 2 percent and 20 percent of the project cost.

“The MOX project record shows that rework cost is less than 0.5 percent,” Trice wrote Wilson. “In total, the rework on this project has been approximately $8 million of the $4.5 billion spent to date and we continually work with the craft personnel to improve this performance.”

He said the MOX facility is more than two-thirds complete, at just over 68 percent.

“Through sometimes difficult circumstances we are getting the job done. While more money would certainly speed up construction, we have been able to build and complete 4 percent of the structure every year at $345 million, proving that we can indeed make progress at that level. Our goal next year is to exceed 75 percent physically complete.”

CB&I AREVA MOX Services said this week the non-cited welding violation discovered by NRC has nothing to do with rework and originated from an outside vendor/supplier. The group added that associated corrective actions will be completed by the end of the year and that no significant changes in the field are anticipated.

NRC inspectors, however, determined that the violation “was more than minor” because the engineering change process used by the contractor was not in accordance with MOX’s Quality Assurance Plan.

“Failure to design the welded connections in accordance with code requirements will result in the need to perform a code deviation or rework of the welds,” the report stated.

“It is key aspect of nuclear-grade construction to have welds within specifications that are carefully documented and checked, so any indication that there seems to be some irregularities in the welding are a concern,” Lyman said.

He added that the Union of Concerned Scientists hopes the government will pay more attention to what is going on at the plant and investigate more. Construction of MOX, which began in 2007, was initially projected to cost $1.7 billion in 1999, but that was revised in 2013 to $7.7 billion.

“The larger problem with this project is that there has been a systematic lack of forward thinking,” he said. “There has always been a rush to move forward, a rush to build without a complete design. That’s been identified now as one of the major problems leading to cost overruns and delays.”

 

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