A storage tank at the Hanford Nuclear Reservation in Washington state has leaked more than a million gallons of cooling water contaminated by radioactive waste, an amount far surpassing any other admitted leak of potentially deadly materials at the site.
State officials expressed outrage at learning only last week of the enormous leak despite repeated, extensive discussions with Hanford officials about 149 single-shell tanks considered to be the site's most serious environmental problem.
Public documents of the federal Department of Energy and Westinghouse Hanford Co., the main contractor at the arid, sagebrush-covered site near Richland, Wash., estimate the leak from the single-shell tank at only 5,000 gallons and don't mention the cooling water added to keep the tank from exploding.
But recently revealed memos between the federal agency and Westinghouse show that water put on top of the radioactive waste in Tank 105A over a decade ending in 1978 ran out of the concrete structure and into the desert soil.
One Energy Department memo dated last week states that "the cooling operation transported tank contents into the soil."
The aging, single-wall tanks, along with 28 double-shell tanks, contain the leftovers from four decades of making plutonium for bombs.
A letter sent Friday by the Washington state Ecology Department to the U.S. Energy Department asks why the huge leak just now became public and to what extent the soil, and possibly ground water, are contaminated from the cooling water, which helped flush radioactive waste out of the tank.
One state official said he expected to see substantial contamination at the site and indications of ground water pollution.
The largest previously reported leak was a discharge of 115,000 gallons in 1973 from another single-shell tank. The Energy Department says that radioactivity from that leak has remained in the soil beneath the tank and that it will not affect areas around the 560-square-mile Hanford site on the Columbia River.
Ken Morgan, spokesman for the Energy Department, said the massive discharge was "old news that everyone knows about" and that former Hanford manager Mike Lawrence briefed the state last October in Richland on the problem.
But the briefing did not mention cooling water or discharges and instead concerned a Jan. 28, 1965, steam explosion in the tank, when water got trapped between the tank's steel liner and concrete base, with venting occurring for 30 minutes. The million-gallon tank was built in 1955.
The state and the Energy Department have agreed to a 30-year cleanup for Hanford, believed to be the nation's most polluted radioactive site. Although disposal of tank wastes is considered the cornerstone of the May 1989 cleanup agreement, the problem of Tank 105A was not discussed during the 14 months of negotiations.