VERNON, Vt. – After pumping out 130,000 gallons of contaminated groundwater, removing 240 cubic feet of tainted soil and spending about $10 million responding to a leak of radioactive tritium, Vermont Yankee officials said Tuesday it will be at least three months before the cleanup is complete.

But they say there’s no evidence the isotope made it into drinking water and that water samples from the neighboring Connecticut River continue to show no detectable tritium.

In a meeting held at the plant Tuesday, representatives of the troubled nuclear power plant and corporate parent Entergy Corp. released the results of an in-house analysis performed after the Jan. 7 revelation of the leak of tritium — a carcinogen that’s been found at dozens of the nation’s nuclear reactors.

It blamed the leak on a design flaw in the 38-year-old plant, leftover insulation from a construction job that kept contaminated water from being collected properly and a separate pipe added to the plant in 1978 that created a pathway that allowed the water to seep into soil.

The report by Vermont Yankee, which was to be delivered to state regulators later Tuesday, also pointed the finger at plant management for not fully implementing groundwater protection measures recommended by the nuclear industry, which it said might have prevented or identified the tritium leak quicker.

Tritium, which occurs in nature but is also a product of fission, has been linked to cancer if ingested, inhaled or absorbed through the skin in large amounts.

Its discovery at Vermont Yankee came as plant owners sought permission for a 20-year extension that would allow the 650-megawatt plant to continue operating past 2012, when it’s currently scheduled to close.

Following the revelation, Vermont lawmakers passed a resolution to block the plant from operating past 2012.