Radioisotope leakage accident.

Nippon Paper Industries Co.,Ltd.

We are pleased to inform you that Nippon Paper Industries Co.,Ltd. confirmed a leak of radioisotopes on March 25, 2025, and reported it to the Nuclear Regulatory Commission on the same day in accordance with laws and regulations.

In the research building of our R&D Division, we use the weight scale (hereinafter referred to as") used to measure the weight of paper. Since it was confirmed that the leakage of the radioisotope 85Kr (Krypton 85) enclosed in the nuclear isotope was confirmed, it was determined that it was a legal reporting event based on the provisions of Article 31-2 of the Act on the Regulation of Radioisotopes, etc., and promptly reported it to the Nuclear Regulatory Commission.

As a result of measuring the radiation dose in the radiation equipment room (5.95 m×5.50 m), which is the control area where the main tsubometer is installed, it has been confirmed that the result is a measurement of natural radiation levels, and our employees in charge of the work of using the main tsubometer have not been found to have any health effects.

Since the radiation equipment room is constantly ventilated, we believe that the leaked krypton gas has diffused and diluted, and that there is no impact on the environment or the human body.