The large sinkhole that caved in a tunnel filled with radioactive waste at a sprawling Washington state nuclear waste repository may have gone unnoticed for days before its discovery because workers do not patrol tunnel sites daily, a spokesman for the U.S. Department of Energy said Thursday.
The sinkhole was found Tuesday, prompting an emergency at the Hanford Nuclear Reservation with evacuations of some workers and orders for others to stay inside buildings scattered across the 500 square-mile safekeeping location for radioactive waste dating from World War II.
Authorities plan to investigate why and when the roof of the tunnel suffered a partial cave-in, creating the sinkhole that poured dirt into the tunnel containing railroad cars with nuclear waste, the agency said.
The cave-in could have happened as many as four days before its discovery on Tuesday, said energy department spokesman Mark Heeter.
“We don’t know exactly when it occurred,” Heeter said.
Washington state officials were taken aback upon learning after the collapse that tunnel inspections were made on what they called an infrequent basis.
“It’s not acceptable that the hole could have been open for four days,” said Alex Smith, nuclear waste manager for the Washington state Department of Ecology, which helps regulate the Hanford site.
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