On the heels of a discovery of trace amounts of tritium in the groundwater near the Vermont Yankee nuclear power plant, the Vermont Senate Wednesday voted to block the state's only nuclear plant from operating beyond its current license, expiring in 2012.

The Senate's 26-4 vote against a 20-year extension of Vermont Yankee's license is the first time lawmakers have formally weighed in on the question. Vermont is the only state in the U.S. where the legislature is a stakeholder in a nuclear plant's relicensing.

Calling it a "moment of tremendous opportunity for Vermont" Vermont senator Bernie Sanders welcomed the decision from the Vermont Senate.

“When Vermont Yankee was built, the promise and expectation was that the plant would operate for 40 years and shut down," said Sanders in a statement. "Today the Vermont Senate reconfirmed that long-established understanding. I agree with the Senate’s decision."

Although some argue that the amount of tritium leaking from the Vermont Yankee is relatively minuscule and even harmless, it is still somewhere between three and forty times federally-allowed levels. Higher than normal levels of the cancer-causing tritium found in groundwater testing wells would also indicate that tritium is likely finding its way into the nearby Connecticut River.

And when you step back and look at the state of nuclear power plants currently operating in the U.S., you would find as many as one-quarter of nuclear power plants are leaking tritium beyond what is legally allowable.

With the Obama administration recently giving strong support to nuclear by guaranteeing loans and moving forward with licensing new plants, the important political implications of the Vermont Senate's move are not entirely certain.

The Vermont Yankee is just one of several nuclear power plants in this country approaching the end of its intended life. On the one hand, opponents of nuclear power will say that the current state of the Vermont Yankee and other aging plants are at the core of the argument against investing billions of dollars into new nuclear power generation. On the other hand--and somewhat ironically--nuclear proponents will use the exact same evidence to argue in favor of developing a new generation of nuclear power plants to replace the old.

Vermont Yankee and its owner, New Orleans-based Entergy Corp., vowed to fight the Vermont Senate's Wednesday vote.

"The effort to win a 20-year renewal of Vermont Yankee's operating license is far from over," company spokesman Larry Smith said in a statement. "We remain determined to prove our case to the Legislature, state officials and the Vermont public."

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