Sep. 30--BRATTLEBORO -- Even though Entergy has promised to put $51 million toward the cost of decommissioning Vermont Yankee nuclear power plant in Vernon, that's $7 million short of how much it will take to make the trust whole, according to a Sept. 29 letter from the Nuclear Regulatory Commission.

In the letter, the NRC is demanding to know how that shortfall will be met.

Entergy has 30 days to reply to the NRC's request. It had no comment on the letter at this time.

In July, the NRC informed the operators of 26 nuclear power plants around the country that because of the sub-prime crisis on Wall Street, their trust funds were inadequate to pay for cleanup of their nuclear power plant sites when their reactors are shut down.

The NRC told Entergy that Yankee's fund was short a little more than $87 million.

Entergy, which owns and operates Yankee, responded that because of a rebound in the stock market, the fund was actually only short by $58 million. In response to the shortfall, it promised to deposit $51 million directly into the decommissioning trust fund.

But exactly where it would invest the other $7 million wasn't clarified, thus the NRC sent a letter to Entergy on Sept. 29 asking it to identify where that money will be going.

"There are different financial instruments a company can use to address a decommissioning fund shortfall, including a surety bond, letter of credit or a line of credit," said Neil Sheehan,

spokesman for the NRC. "Simply put, we want to know how the other financial instruments Entergy plans to use to bridge the gap between the $51-million cash deposit and the $58-million estimated shortfall."

In September 2007, the trust fund had accumulated $440 million for the eventual cleanup of the site in Vernon. But 13 months later, the fund had lost $77 million, down to $364.4 million.

By February 2009, the fund hit a low mark of $347 million. Since then, however, the fund has grown almost to the point it was at prior to the stock market tumble.

By August of this year, the fund had recovered to $411 million.

The NRC estimates it will cost about $550 million to clean up the site when the plant is shut down.

According to NRC regulations, a plant operator needs to show a 2 percent annual rate of return "provided that the site-specific estimate is based on a period of safe storage that is specifically described in the estimate."

The average annual rate of inflation from 1914 to the present has been 3.41 percent. That means, on average, the fund has to grow 5.41 percent per year to reach the required NRC levels.