* Entergy wants Vermont Yankee to run for 20 years * Vermont wants to shut reactor * State Public Service Board still to rule March 20 (Reuters) - Entergy Corp won another victory in its quest to keep the Vermont Yankee nuclear power plant operating for another 20 years when a federal judge again blocked the state from shutting the 40-year old reactor - this time over a spent fuel issue. In January, U.S. District Judge J. Garvan Murtha ruled the state could not shut Vermont Yankee after determining the state tried to shut the reactor over radiological safety concerns, which is a federal, not a state, responsibility. Vermont appealed that ruling to the Second Circuit Court of Appeals in New York. After Judge Murtha's January ruling, some in Vermont still believed the state could shut the 620-megawatt plant this month through the Vermont Public Service Board, which is considering Entergy's application for a new certificate of public good to allow the reactor to run for another 20 years. The state argued the quasi-judicial Public Service Board, which oversees Vermont's public utilities and Vermont Yankee, could shut the plant by preventing Entergy from storing any fuel burned in the reactor beyond March 21, when the unit's original 40-year operating license was to expire. All of the fuel burned in a reactor must be stored in the plant's spent fuel pool to cool for several years before it could possibly be transferred to another storage facility. Pending a decision on the state's Circuit Court appeal, Judge Murtha blocked the state from shutting the plant over the spent fuel issue because he found a shutdown would cause "irreparable harm" to Entergy and the plant's workers. "We are pleased Judge Murtha has issued an injunction against any action by Vermont to compel Vermont Yankee to shut down because of the storage of spent fuel from operations beyond March 21, 2012," Entergy said Tuesday in a statement. The judge however ruled Entergy still had to seek a certificate of public good from the state Public Service Board. The Public Service Board meanwhile on Monday denied Entergy's motion on how certain provisions of Vermont law apply to the continued operation of the reactor and spent nuclear fuel storage. "We are reviewing the details of the judge's decision as well as Monday's order from the Vermont Public Service Board, and we are withholding further comment at this time," Entergy said in the statement. It is not certain when the Public Service Board will decide on Entergy's application for the certificate of public good.