The Nuclear Regulatory Commission will be sending a radiation specialist to the Indian Point nuclear plant in Buchanan on Thursday to inspect a monitoring well.
Entergy, which operates the plant, revealed last week that a radioactive isotope of hydrogen had contaminated wellwater at the plant.
Indian Point operators say they believe the leak occurred during recent maintenance work.
Inspectors are now looking at specific pipes at the plant to fix the problem. They stress that the level of radioactivity is so low that it does not impact public health or safety.