Errors Found in Radiation Exposure Assessment

Shin-Hanul Nuclear Power Plant in Uljin, North Gyeongsang Province

Korea Hydro & Nuclear Power Corp. (KHNP) is planning to reassess the radiological environmental impacts of the 24 nuclear power plants in South Korea starting from January next year.

In January this year, the Nuclear Safety and Security Commission told KHNP to conduct the reassessment. The state-run company is making preparations with the Korea Institute of Nuclear Safety, and they are supposed to report the result of the preparations to the commission soon.

The commission issued the administrative order for errors and omissions detected during its pre-approval review related to the operation of Shin-Hanul Unit 1. Specifically, external exposure was omitted in the exposure dose assessment related to gaseous radioactive substances and a practically impossible exposure pathway was found in the exposure scenario.

According to a report Korea Hydro & Nuclear Power submitted to the commission in August last year, the effective dose of every facility inside the site is 0.155 mSv, which is 62 percent of the annual limit. However, the figure is as high as 0.227 mSv in the case of the assessment preceding error correction. The annual dose related to the unit may rise and exceed the statutory threshold after error correction.

The reassessment is supposed to cover ground surfaces where gaseous radioactive effluents can land and points where exposure may result from ingestion. In addition, exposure point-related maritime domain ranges will be changed and thyroid dose reassessment will be done after exposure pathway addition. A total of five sites will be subject to the reassessment.

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