* Tritium led state to oppose license renewal in 2010
* Reactor to shut by 2012 unless license renewed
NEW YORK, Jan 21 (Reuters) - Radioactive tritium has been found in a water sample from a monitoring well at Entergy Corp's (ETR.N) Vermont Yankee nuclear power plant, the company said on Friday, a year after the isotope was identifed in a leak at the facility.
"This week Vermont Yankee received positive indications for tritium in a previously unaffected monitoring well located about 150 feet to the north of the area affected by the leak that was identified in January 2010," plant spokesman Larry Smith said in an email.
The tritium leak identified last year hurt Entergy's effort to convince Vermont politicians that the 620-megawatt Vermont Yankee plant should continue to operate after its license expires in 2012.
Entergy is now trying to convince a new state legislature and the federal Nuclear Regulatory Commission (NRC) that the plant's license should be extended for another 20 years.
Tritium is a mildly radioactive isotope of hydrogen that occurs naturally in very small amounts in ground water. It is also a byproduct of nuclear power production.
Smith said the company did not understand the latest elevated reading and would investigate to identify its cause.
The reading came from a well installed in November 2010 to monitor for tritium. It is not a drinking well and does not pose a risk to public health and safety, Entergy said.
Over the past year, the company has found tritium in water samples that was caused by the migration of tritiated water released by the January leak in the advanced off gas system pipe tunnel which was sealed and repaired earlier this year.
The amount of tritium found this week was 9,200 picocuries per liter, which is significantly below the NRC's required level to report tritium findings of 30,000 picocuries per liter and the U.S. Environmental Protection Agency's standard for permissible levels of tritium in drinking water of 20,000 picocuries per liter, Entergy said.
A picocurie is one trillionth of a curie. To place these figures in context, Entergy said there were at least 6 curies (or 6 trillion picocuries) of tritium in an average self-illuminated red "EXIT" sign. ----------------------------------------------------------- PLANT BACKGROUND/TIMELINE STATE: Vermont COUNTY: Windham TOWN: Vernon OPERATOR: Entergy Nuclear OWNER(S): Entergy Corp CAPACITY: 620 MW UNIT(S): General Electric Boiling Water Reactor FUEL: Nuclear DISPATCH: Baseload COST: $183 million TIMELINE: 1972 - Reactor enters commercial service 2002 - Entergy buys reactor for $180 million from Vermont
Yankee Nuclear Power and enters a 10-year power
purchase agreement to sell power back to the
former owners for about 4.5 cents per kilowatt
hour Jan 2006 - Entergy files with NRC to renew the original
40-year operating license for an additional 20
years Sep 2006 - Atomic Safety and Licensing Board (ASLB) admits
five contentions on application from New England
Coalition (NEC) and Vermont Department of Public
Service Nov 2008 - ASLB rules in Entergy's favor on four contentions
but says Entergy's metal fatigue analyses for two
reactor vessel nozzles do not comply with all
requirements Mar 2009 - Entergy submits revised metal fatigue analysis for
nozzles Apr 2009 - NEC challenges Entergy's metal fatigue analysis
and proposes new contention Jul 2009 - ASLB accepts Entergy's metal fatigue analysis,
rejects NEC contention as not timely Jul 2009 - NEC appeals ASLB decision on metal fatigue to the
Commission Jan 2010 - Entergy identifies tritium leak Feb 2010 - Vermont Senate votes 26-4 against authorizing the
Vermont Public Service Board to issue a
certificate of public good that would allow for
the license renewal. Vermont is the only state in
the nation with the authority to block a license
renewal. Entergy officials have said the state
gained that authority when Entergy bought the
plant Mar 2010 - Entergy stops tritium leak Jul 2010 - Commission rules ASLB should have ruled in
Entergy's favor on original metal fatigue
calculations and remands to ASLB to give NEC
opportunity to submit a revised contention
challenging the aging management program for metal
fatigue Aug 2010 - NEC submits contention having to do with aging
management program for electric cables Oct 2010 - ASLB denies NEC contention on aging management
program for electric cables as not timely Nov 2010 - Entergy mulls sale of Vermont Yankee 2011 - Entergy will get another chance to convince state
legislators to approve of a new license once the
new session starts Q2 2011 - Entergy to make decisions about next refueling
expected in autumn 2011 - Entergy will not confirm
but analysts have said the company must decide
whether to buy fuel for the refueling 2011-12 - NRC Commission still needs to decide on an
appeal from the NRC staff on a ruling in Entergy's
favor by the ASLB that Entergy must inspect the
reactor nozzles. The staff did not think it was
appropriate for the ASLB to order the company to
conduct the inspection immediately rather than at
some time before renewing the license. After
deciding that appeal, which electricity traders do
not consider important since Entergy has already
conducted the ASLB requested inspections, and any
other appeals, the Commission can approve of the
renewal. The Commission however is not bound by
any timeline in making a decision Mar 2012 - Reactor operating license expires and unit to
retire unless license renewed. The reactor however
can continue to operate so long as the renewal
process is ongoing. (Reporting by Scott DiSavino; editing by Jim Marshall)