By SHANNON DININNY 02/22/13

YAKIMA, Wash. — Six underground tanks that hold a brew of radioactive and toxic waste at the nation's most contaminated nuclear site are leaking, Washington Gov. Jay Inslee announced Friday.

The leaking tanks strike another blow to federal efforts to clean up south-central Washington's Hanford nuclear reservation, where any successes often are overshadowed by delays, budget overruns and technological challenges.

State officials just last week announced that one of Hanford's 177 underground tanks was leaking in the range of 150 to 300 gallons a year, posing a risk to groundwater and rivers. So far, nearby wells haven't detected higher radioactivity levels.

Inslee traveled to Washington, D.C., this week to discuss the problem with federal officials. He said Friday he learned during meetings that six tanks are leaking waste.

"We received very disturbing news today," the governor said. "I think that we are going to have a course of new action and that will be vigorously pursued in the next several weeks."

Inslee noted there are legal and ethical considerations to cleaning up the Hanford site, both at the state and national level. He also stressed the state would impose a "zero-tolerance" policy on leaking radioactive waste into the soil and insisted that the Department of Energy fully clean up the site.

The tanks already are long past their intended 20-year life span. They hold millions of gallons of a highly radioactive stew left from decades of plutonium production for nuclear weapons.

The leaking tanks were missed because graphs that monitor the waste levels were evaluated only over a short period, rather than a longer period that might have shown the levels changing, Inslee said.

"It's like if you're trying to determine if climate change is happening, only looking at the data for today," he said. "Perhaps human error, the protocol did not call for it. But that's not the most important thing at the moment. The important thing now is to find and address the leakers."

The federal government created Hanford in the 1940s as part of the top-secret Manhattan Project to build the atomic bomb. The government spends $2 billion each year on Hanford cleanup – one-third of its entire budget for nuclear cleanup nationally. The cleanup is expected to last decades.

Central to the effort is the construction of a plant to convert millions of gallons of waste into glasslike logs for safe, secure storage. The $12.3 billion plant is billions of dollars over budget and behind schedule.

Inslee and Oregon Gov. John Kitzhaber have championed building additional tanks to ensure safe storage of the waste until the plant is completed. Democratic Sen. Ron Wyden of Oregon said earlier this week that he shares their concerns about the integrity of the tanks, but that he wants more scientific information to determine it's the correct way to spend scarce money.

Wyden noted the nation's most contaminated nuclear site – and the challenges associated with ridding it of its toxic legacy – will be a subject of upcoming hearings and a higher priority in Washington, D.C.