A new study prepared for the CB&I AREVA MOX Services Board of Governors states that switching from the MOX method of plutonium disposition to a downblending approach could result in a nuclear chain reaction. But the National Nuclear Security Administration (NNSA) said a criticality incident cannot result from storing downblended plutonium, and that the finding isn’t credible. The feds are sticking to their belief that downblending, the preferred option outlined in President Barack Obama’s fiscal 2017 budget request, is the best path forward to carry out a deal in which the United States and Russia must each dispose of 34 metric tons of weapon-usable plutonium.
Energy Secretary Ernest Moniz said last year that funding the MOX method, which includes the unfinished Mixed Oxide Fuel Fabrication Facility (MFFF) being constructed at the Savannah River Site in South Carolina, is unsustainable due to its exploding costs – which he forecast at $1 billion annually to adequately fund the entire project. Instead of MOX-ing the plutonium by converting it into commercial nuclear fuel, downblending would use inhibitor materials to dilute the plutonium at SRS. Then, the plutonium would be sent to a federal repository, most likely the Waste Isolation Pilot Plant (WIPP) near Carlsbad, N.M.
High Bridge Associates earlier this month released a report for CB&I AREVA MOX Services, which is building the plutonium conversion plant at Savannah River. The project management specialist found that the plutonium packing in the downblending method would be crushed over time at WIPP as the salt chambers that make up the facility eventually start to close up. Once that happens, High Bridge said a high likelihood of uncontrolled criticality would ensue and result, at a minimum, in the release of large amounts of energy and radioactive products into the environment.
“The extremely high pressures created as the salt cavern closes in on the storage drums will force the plutonium closer together, creating the geometry of crushed storage drums which facilitates a critical chain reaction,” High Bridge wrote.
But NNSA spokeswoman Francie Israeli said the Sandia National Laboratories in New Mexico, at the request of the Energy Department, reviewed the assertions of the High Bridge report and concluded that the risk of criticality issues at WIPP are unfounded. “Sandia’s review addresses the criticality issue that is the basis for the High Bridge report’s assertions,” she stated.
