The waste endangered workers and brought a halt to cleanup of the leaky underground single-shell tanks.
The spill occurred on July 27, 2007, when contractor CH2M HILL Hanford Group was pumping waste from a tank. Workers tried to unblock a pump by running it in reverse. This resulted in a high-level waste spill to the ground.
"Over 80 gallons of highly radioactive tank waste spilled to the environment," said Jane Hedges, manager of Ecology's Nuclear Waste Program. "Before the spill was discovered, a series of poor decisions put workers in grave danger from exposure to the tank waste and vapors. This accident calls into question the adequacy of the safety culture which is so critical at the tank farms."
Hedges, who leads the state's oversight of the Hanford cleanup, said, "We are troubled by the length of time it took CH2M HILL and the Department of Energy to determine there was a release of radioactive tank waste. There was a delay of more than seven hours from the time the first high radiation readings were discovered. This is completely unacceptable."
The interior of a single-shell tank at Hanford containing highly radioactive waste (Photo courtesy DOE)
The state agency investigated the circumstances surrounding the spill, including the equipment design, incident notification, and emergency response. A series of administrative and engineering failures were found to have contributed to this accident.
The DOE conducted its own investigation using procedures reserved for the most serious of accidents at agency facilities, and identified contributing causes to be inadequate engineering reviews and testing, work controls, industrial hygiene, radiological protection, medical response, and emergency management.
Ecology's penalty cites two violations. The first involved inadequacies in the design of the waste retrieval system.
"The Raw Water System used to provide dilution water for the pump had no backflow equipment to prevent waste from backing up into it," said Eric Van Mason, inspector for the state agency.
The system is designed to supply water, not to transfer or contain waste. When the pump was run in reverse, tank waste traveled into a rubber hose above the ground. The rubber hose ruptured, resulting in the spill.
The second violation involved inadequate engineering reviews. The Tank Waste Retrieval System design was not adequately or fully reviewed in accordance with state regulations.
Van Mason said, "The inspection found that too few staff were on the job to manage the incident during the graveyard shift. Inspections determined that lighting was inadequate in the pump pit area, and poor positioning of the S Tank Farm video camera also contributed to the delay in response to the accident."
As a result of this accident, all work related to retrieving the liquids from Tank 241-S-102 has been stopped. Additionally, all tank waste retrieval work throughout the tank farms has been suspended until the contributing factors can be identified and resolved and work can resume safely.
The Department of Energy has already missed several deadlines for retrieval of waste from the 149 single-shell tanks.
"Radioactive tank waste is the greatest human health and environmental risk at Hanford," said Hedges. "Getting the waste out of the aging, leaky Hanford tanks is the state of Washington's top cleanup priority. The mismanagement of the retrieval work that caused this spill has set back the already delayed tank retrieval work even further."
Copyright Environment News Service (ENS) 2007. All rights reserved.