The Department of Energy says it will take more time on a plan to send radioactive waste from eight Hanford tanks to a national repository in New Mexico for disposal rather than turning it into a stable glass form.

The move comes as it applies to the Environmental Protection Agency for recertification of the Waste Isolation Pilot Plant, or WIPP, in New Mexico, the nation's repository for transuranic waste, for another five years.

The New Mexico State Environment Department has refused to accept Hanford tank waste at WIPP, saying the waste is legally high-level radioactive waste, not transuranic waste. Hanford waste classified as transuranic typically is debris such as laboratory equipment and building rubble contaminated with plutonium, but DOE also earlier identified eight tanks that have waste it believes could be reclassified as transuranic.

DOE tank wastes that potentially could be reclassified have been removed from an annual transuranic waste inventory report, according to a letter to EPA from Frank Marcinowski, DOE deputy assistant secretary for regulatory compliance for environmental management. DOE is proposing that the waste instead be included in its WIPP recertification application in a potential transuranic waste inventory report in an appendix.

"This is another indication that Energy Secretary (Samuel) Bodman and DOE are not in any hurry to deal with the tanks," said Don Hancock of the Southwest Research and Information Center, a New Mexico environmental watchdog group. The group also sees the move as putting up obstacles that could prevent the next presidential administration from sending tank waste to New Mexico until 2014, the length of the next WIPP recertification period.

Marcinowski said the proposed language for the recertification application could mean a schedule slip for sending the waste to New Mexico, but does not mean that DOE is backing off from the approach. DOE could submit a change request after the recertification application is approved, he said.

DOE is proposing listing the waste as potential transuranic waste in the WIPP recertification application because of "uncertainty in the process of steps to follow to make a waste determination and technical issues," Marcinowski said.

The schedule already is uncertain for retrieving and treating the 53 million gallons of radioactive waste from 142 single-shell tanks and eventually the 28 sturdier double shell tanks. Under the latest proposal being considered in the renegotiation of the Tri-Party Agreement, the deadline to empty the single shell tanks would be extended from 2018 to 2040. The waste from the tanks then would have to be treated by 2047.

If the waste remains classified as high level waste it likely would be vitrified, or turned into a stable glass form, for disposal. Packaging it for disposal at WIPP would be less expensive and mean less waste to be sent to the Hanford vitrification plant under construction, reducing the time it needs to be operated.

Earlier DOE estimates put the cost savings for sending the waste to New Mexico at $459 million. About $40 million had been spent on the project before work stopped over uncertainty about whether the waste could be sent to WIPP.

The Southwest Research and Information Center wants the tanks cleaned up, but believes the waste should be vitrified, Hancock said.