Hanford officials should move radioactive cesium and strontium capsules to dry storage as soon as possible, in part because of the potential risk posed by a severe earthquake, federal inspectors say.
The 1,936 capsules are stored underwater at Hanford's Waste Encapsulation and Storage Facility (WESF) in central Hanford, which has been operated almost a decade longer than it was designed to last.
It also is the DOE facility that is at greatest risk in the case of a natural disaster beyond what it was designed to sustain, according to a memo by the Department of Energy's Office of Inspector General.
A severe earthquake could result in the loss of power or water in the pool, the memo said.
The memo, authored by David Sedillo, was publicly released Wednesday. It's directed at DOE Hanford officials at the Richland Operations Office, but stops short of making a formal recommendation.
"We acknowledge the budgetary challenges facing the department and its impact on moving the capsules into dry storage," the memo said. "However we suggest that the manager (of the) Richland Operations Office expeditiously proceed with its plans to pursue a dry storage alternative to support transfer of the capsules out of WESF at the earliest possible time frame."
Steps were taken to reduce the risk of a severe earthquake to the storage pool after the nuclear disaster three years ago in Fukushima, Japan.
The cesium and strontium were recovered from Hanford's underground waste tanks from 1974-85, packed in corrosion-resistant capsules and placed in underwater storage at WESF. The waste is left from the past production of plutonium at Hanford for the nation's nuclear weapons program.
The capsules, which are about 22 inches long, hold material with 106 million curies of radioactivity, or 32 percent of the total radioactivity at Hanford. The 13 feet of water covering them helps cool the capsules and protects workers from radiation.
The capsules have been planned to be sent to the proposed Yucca Mountain, Nev., national repository, which DOE no longer plans to develop. That could leave the capsules stored at Hanford until 2048, when DOE plans to open a repository at a location yet to be determined.
WESF has been operating for almost 40 years and the concrete in the cells of its underwater pool has begun to deteriorate from radiation exposure.
"Weakened concrete in the walls of the pool increases the risk that a beyond-design earthquake would breach the walls, resulting in the loss of fluid, and thus, loss of shielding for the capsules," the Office of Inspector General memo said.
However, the memo also noted that an earthquake or other disaster more severe than WESF was designed for is "extremely improbable."
After the Fukushima disaster, DOE contractor CH2M Hill Plateau Remediation Co. rearranged about 800 of the underwater capsules to better distribute their heat. The work was done in 2012, which was the first major relocation of the capsules in about 20 years.
A loss of water or cooling in the pool could cause the capsules to corrode or be breached. The metal of some of the capsules previously was damaged by being taken in and out of water for a program that rented hundreds of them out for research and industrial use.
CH2M Hill has plans to add water to the pool using tanker trucks in an emergency and has conducted emergency drills.
DOE had planned to start repackaging and then putting the capsules in dry storage in Hanford's T Plant in late 2005, and former contractor Fluor Hanford had requested bids for the project in 2003. However, the work was canceled as DOE decided it had more pressing environmental cleanup concerns.
Now removing the capsules to dry storage is crucial because a national repository for them will not be available for decades, the memo said.
DOE has asked CH2M Hill to fully document the need for long-term dry storage, and CH2M Hill continues to work on that report.
CH2M Hill also has issued a request for information to engineering firms in August to help it better estimate the cost and feasibility of dry storage.
DOE Hanford officials would like to move to dry storage, but have other pressing needs, the memo said. The administration's budget proposal for fiscal 2015 would cut spending for projects under the Hanford Richland Operations Office by almost $100 million.
"The department has taken the steps needed to ensure safety of the material until funding is available to transfer the capsules into dry storage," said Ray Corey, DOE assistant manager for Hanford river and plateau work, in a statement.
The Office of Inspector General memo said that given funding issues, that perspective is not unreasonable.
The existing structure is safe and can still withstand the emergencies considered when it was designed, DOE told the Office of Inspector General.
If DOE can find the money to move the capsules to dry storage, it would save money long-term, the memo said. The move would cost an estimated $83 million to $136 million. But then the storage cost would drop to $1 million a year compared to the current underwater storage cost of $7.2 million annually.
DOE eventually must move the capsules to dry storage, so the sooner that is done, the more money can be saved in reduced operating costs, the memo said.
DOE agrees that moving the capsules to dry storage would reduce operating costs and improve safety, Corey said.
The Office of Inspector General previously has suggested that DOE assign funds to projects nationwide based on risk rather than focusing on work to meet legal deadlines such as those in Hanford's Tri-Party Agreement, and it repeated that advice in the memo on the capsules. That strategy would make moving the capsules to dry storage a high priority.