Nuke panel explores entombing reactors

Tuesday, Dec. 14, 1999 | 11:11 a.m.

The Nuclear Regulatory Commission was expected today to release a report that explores entombing commercial nuclear reactors on site, rather than shipping thousands of tons of contaminated metals to a proposed Yucca Mountain repository.

If the commission decides to entomb a reactor on site once it is shut permanently, radioactive steel vessels, pipes and other components would be filled with concrete or grout, sealing the contaminated parts where they stand for up to 130 years, until radiation drops to a safe level.

Radiation from cesium-137, cobalt-60, technetium-99, niobium-94 and nickel-59 poses a risk to workers dismantling the reactors if the metals have to be moved to a central repository.

While entombment might present an alternative to packing Yucca Mountain, 90 miles northwest of Las Vegas, with thousands of tons of contaminated metal, commission staff noted that difficult technical and legal issues face such a scheme.

The plan also would not derail the utility industry's efforts to ship thousands of tons of highly radioactive spent nuclear fuel to Nevada for storage at Yucca Mountain.

Yucca Mountain is the only site under study by the Department of Energy to contain the nation's estimated 77,000 tons of highly radioactive reactor waste and Defense Department rubble from 44 years of nuclear weapons building.

The former Soviet Union entombed the crippled Chernobyl Unit 4 reactor in a sarcophagus after a nuclear meltdown in April 1986 to shield the environment from radiation after 135,000 people in an 18-mile radius were evacuated. Cracks have already appeared in that container.

The commission's staff noted that although all of the radioactive waste and reactor scraps could one day go to Yucca Mountain, the site has not been approved and the DOE has not agreed to accept contaminated reactor parts. Lawsuits, technical delays and other hurdles could delay the opening for decades.

If Yucca Mountain is approved, it is not expected to receive nuclear waste for another 15 years, the report says.

With entombment on site, Yucca Mountain would receive only spent nuclear fuel, not every scrap of contaminated reactor metal as well.

Just under 30 nuclear power plants in the U.S. have been shut down and require some kind of plan to protect the public and the environment from the radioactive remains.

The Nuclear Regulatory Commission decided to look at an entombment option because of the high costs of disposing of the contaminated guts of nuclear power plants.

It could cost $251 million for immediate cleanup and burial of reactor parts, plus monitoring and security of a site for 121 years, the commission's report says.

If a reactor site could be encased in steel, concrete, sand, grout and other barriers with remote monitoring and periodic radiation testing, the expenses would drop to $121.9 million.

DOE's Pacific Northwest National Laboratory began the study in 1997 leading to today's workshop at the commission's headquarters in Rockville, Md. The laboratory discovered a precedent for burying reactors at the site.

Three U.S. nuclear reactors, built by the DOE's predecessor the Atomic Energy Commission, have been buried on site since 1954. They include:

The Nuclear Regulatory Commission is also concerned about handling the DOE's most contaminated site, Hanford, Wash., which once made plutonium for nuclear weapons.

Tanks filled with liquid nuclear waste and eight reactors that operated from 1944 to 1971 are under watch at Hanford. Entombment is possible and would be cheaper than removing the reactors.

The report said that historical evidence shows that concrete structures covered with soil have remained intact for thousands of years. With modern materials and techniques, most structures would remain intact and resistant to water for 500 years or more, plenty of time for the radiation to fall to safe levels.

Barriers to entombment include sites with high water tables, nuclear reactors near rivers and populated areas, and reactors near saltwater, which increases corrosion of contaminated steel and concrete structures.