RICHLAND — A key Department of Energy report is recommending that the K East Reactor be torn down rather than put into long-term storage like most of Hanford’s other reactors.

DOE will take public comment for 30 days before making a final decision on whether to tear down the reactor or cocoon it.

The Environmental Protection Agency, the regulator on the project, agrees with the report’s conclusion.

“The reactor needs to be removed from the river corridor, and we think that it is better to remove the reactor sooner than later,” said Rod Lobos, EPA environmental engineer.

Five other plutonium production reactors along the Columbia River have been cocooned, or put in long-term storage. They were torn down to little more than their radioactive cores, sealed up, reroofed and left to let their radioactivity naturally decay to more manageable levels over 75 years.

DOE began to discuss the possibility of tearing done the K East Reactor in 2009 because of soil contamination beside and likely beneath the reactor that cannot be removed while the reactor stands. The reactor is 400 yards from the Columbia River.

A new engineering and cost analysis compared options for the K East Reactor. Options included tearing it down immediately; cocooning it and tearing it down after two decades; or the traditional plan of cocooning it and hauling it away for disposal in one piece in 75 years.

The report identified tearing it down immediately as the preferred alternative.

It was not only the least expensive alternative, but also would allow contaminated soil that poses a threat to the river to be cleaned up sooner, according to the report.

The cocooning options would cost $89 million to $108 million, while just dismantling the reactor now would cost about $83 million.

Work to dismantle a reactor core at the Brookhaven National Laboratory has demonstrated that remotely operated equipment can be used to dismantle a core safely, the report said.

The engineering study proposed dismantling the core piece by piece with debris sent to the Environmental Restoration Disposal Facility for low-level radioactive waste in central Hanford.

One of the concerns with cocooning reactors for 75 years is that Hanford landfills for low-level radioactive waste are expected to be long closed by then.

DOE made the decision to cocoon its nine plutonium-production reactors along the Columbia River in 1993. However, earlier this year it amended that decision to clear the way to consider demolition of the K East Reactor.

In 1993 new approaches to reactor core sampling and advanced robotics were not available, according to DOE and its regulators.

To date DOE has cocooned the F, H, D, DR and C reactors. Work is under way to cocoon N Reactor, and B Reactor is proposed to be preserved as a museum. That leaves just the K West and K East reactors, and the K West Reactor basin still is being used to hold radioactive sludge collected from the two K Reactor basins.

Public comment is being accepted by DOE, the Environmental Protection Agency and the Washington state Department of Ecology.