CLINTON - A study of surface and groundwater sites at Clinton Power Station turned up no active leaks and no detectable levels of tritium beyond plant boundaries, according to results released Thursday by AmerGen.

Four samples taken on-site showed slightly elevated levels of the hydrogen isotope that emits weak levels of radiation. AmerGen officials maintain that the tridium levels pose no threat to public safety.

The low level samples detected at the plant ranged from 201 to 545 picocuries per liter of water. A picocurie is one trillionth of a curie, the basic unit used to describe the intensity of radioactivity in a sample of material. The federal standard for safe drinking water is 20,000 picocuries per liter.

The environmental study undertaken by Exelon Nuclear, parent company of AmerGen, began in February after the isotope was detected in groundwater near two Exelon plants in northern Illinois.

AmerGen officials noted in February that since 1992 the Clinton plant has had in place systems that allowed tritiated water to be processed and used on site.

"We are confident that this thorough analysis of tritium has identified any areas of concern at Clinton Station. We take our obligation seriously to be a good environmental steward," said Bryan Hanson, vice president of the Clinton plant.

The Clinton testing was performed on 14 new wells, three existing wells, six surface water locations and the Unit 2 pit drainage system at Clinton. The Unit 2 system drains water from a pit created during original plant construction for a potential second generating unit.

Samples collected at Clinton were analyzed by an independent laboratory.

Tritium is formed naturally in the atmosphere and is a by-product of generating electricity using nuclear energy. Federal guidelines have been established for the release of tririated water from nuclear plants.

Clinton plant officials said Thursday they will continue to conduct periodic tests on water from the network of monitored wells.