CCTV News reported that pollution control authorities in the US state of Minnesota said on Monday (local time)The state's Monticello nuclear power plant, near the Mississippi River, leaked about 1.5 million liters of tritium-contaminated water on Nov. 21.

The energy company that owns the plant notified the Federal Nuclear Regulatory Commission and state governments the day after the accident, but did not tell the public until recently.

The energy company explained that although the amount of tritium in the leaked water was much higher than the standard set by the U.S. Environmental Protection Agency, it did not affect the surrounding groundwater and drinking water and did not pose a threat to the public.

The company is considering building a reservoir for the contaminated water that is 25 percent cleaned up from the spill.

Tritium is a radioactive isotope of hydrogen. Its nucleus consists of a proton and two neutrons. It is radioactive and will undergo beta decay. Its half-life is 12.43 years and atomic weight is 3.016u.

According to the data, tritium is harmful only when inhaled in large quantities because its beta decay emits only fast-moving electrons and does not penetrate the human body.

However, it should be noted that bioactive substances labeled by tritium (such as tritium-labeled thymine), due to their biological activity, will be used by human cells for cell metabolism, resulting in direct internal irradiation, thus seriously harming the health of inhalers.