Construction resumes on Hanford nuclear waste treatment plant

A massive project in the US to stabilize and store 56 million gallons of highly radioactive waste has resumed following a several-week hiatus. The waste was left from cold war plutonium production at the Hanford Site in Washington State. Work on the Waste Treatment Plant (WTP) had been halted last month in response to concerns raised by chief project engineer Gary Brunson. Brunson was, until he resigned a few days ago, the director of the WTP engineering division of the Department of Energy’s Office of River Protection.

“Based on insight gathered from a number of leading scientific experts, [DOE] is now confident construction activities at the high-level waste facility can begin to be ramped back up,” said Energy Secretary Steven Chu and Washington Governor Chris Gregoire in a joint statement released on 16 January. “Over the past several months, the Department of Energy and the State of Washington have worked together closely to ensure the Waste Treatment Plant is on a stable path to resolving the technical issues, completing construction, and beginning to treat waste in the coming years.”

In a 19 December memorandum to Chu and other DOE officials, Brunson had urged that all work on the project be halted “to avoid further nuclear safety compromises and substantial rework within WTP.” Brunson, who has not spoken publicly about his concerns, released his memo through the Seattle-based Hanford watchdog group Hanford Challenge. In an August 2012 memo that was also made public, Brunson had called for DOE to remove the project design responsibilities from Bechtel National Inc, the company that is also building the WTP. DOE’s fast-track “design-build” management approach on the WTP allows construction to begin while the design process is still continuing.

Chu and Gregoire also announced that DOE is exploring whether WTP’s waste treatment operations can begin sooner than 2019, the current proposed start date. That might be accomplished, they said, by bypassing the WTP’s pretreatment facility, in which waste from Hanford’s 177 underground tanks would be separated into low-activity liquid and high-activity solids for faster processing. Instead, all waste would be fed directly to the project’s two vitrification plants, where the radioactive material is to be blended into molten glass for stable storage. Skipping a step would allow the plant to start operating sooner, while work could continue on the pretreatment facility, the largest of the four main structures that constitute the WTP.

According to the Government Accountability Office (GAO), the cost of the project has jumped to at least $13.4 billion, more than triple its original 2000 estimate, and $1.1 billion higher than the DOE’s last official estimate, in 2006. Completion has already been delayed eight years from its initial 2011 date, but GAO warns in a new report that “additional cost increases amounting to billions of dollars and schedule delays of years are almost certain to occur.” Though DOE and Bechtel have blamed insufficient funding for overruns and delays, the GAO claimed unresolved technical challenges were the main culprit. The vitrification process will need to have perfect reliability over the plant’s 40-year lifetime because maintenance or repair will not be possible once waste treatment begins, the report noted.

The GAO was critical of DOE’s design-build management approach. Although DOE in 2010 prohibited the use of design-build for new first-of-a-kind facilities, it is grandfathering the approach in the case of the WTP. While construction of the WTP is currently more than 55% complete, the design is only about 80% complete. Industry guidelines, says the GAO report, suggest that design should be at least 90% complete before the construction of nuclear facilities begins.

The GAO recommended that DOE not resume construction on the WTP’s pretreatment and high-level-waste facilities until the design is 90% complete and critical technologies are tested and verified as effective. In addition, Bechtel’s preliminary documented safety analyses should comply with DOE’s nuclear safety regulations. In response to the GAO report, DOE stated that it had provided Bechtel with sufficient technical and management guidance to produce a high-confidence design and baseline for the facilities.

Among the outstanding technical issues is whether waste sludge will clog the miles of pipes in the WTP. That could lead to the potential buildup of explosive hydrogen gas and the possibility of an accidental nuclear chain reaction.

That concern is heightened by the inadequate understanding of the exact composition of the wastes in each of the tanks. Bechtel has proposed to employ pulse jet mixers that use compressed air to mix the waste, but the technology has never been used for mixing wastes with high solid content like those to be treated at the WTP, according to the GAO. Bechtel is studying the possibility of building an additional facility to remove the largest solid particles from the waste before it enters the pretreatment facility. That would delay completion of WTP by several years and add billions more to its cost.