NSSC Approves Restart of Hanbit Unit 2... Regular Inspection Completed

Regular Inspection of 89 Items Starting This January... Hanbit Unit 2 Criticality Approved

A view of Hanbit Nuclear Power Plant located in Yeonggwang, Jeollanam-do.
Photo by Asia Economy DB

[Asia Economy Sejong=Reporter Lee Jun-hyung] The Nuclear Safety and Security Commission announced on the 31st that it has approved the criticality (restart) of Hanbit Unit 2.

The NSSC conducted a regular inspection of 89 items for Hanbit Unit 2 from January 17th until recently. Based on the inspection results, the NSSC concluded that the reactor criticality of Hanbit Unit 2 can be safely achieved.

Criticality is the state in which a continuous nuclear fission chain reaction occurs inside the reactor, and the number of neutrons reaches equilibrium. A reactor that has reached criticality can be safely controlled and operated.

However, during the inspection of the integrity of the internal steel plates of the containment building, the NSSC identified one location at the vertical wall construction joint where the thickness was below the standard thickness (5.4mm), and welding and repairs were carried out. In the upper dome, 91 abnormal areas were found, including 3 suspected corrosion spots, 2 dents, and simple defects. The suspected corrosion spots on the upper dome were determined to be stains, and the other abnormal areas were addressed according to relevant procedures.

During the regular inspection, the startup transformer, which had been in use for 30 years, was replaced with a new one to prepare for possible failures. Considering that the 2020 typhoon affected the Kori Nuclear Power Plant, the NSSC also improved exposed overhead lines around the startup transformer.

Based on these regular inspection results, the NSSC approved the criticality of Hanbit Unit 2. The NSSC plans to finally confirm safety through eight follow-up tests, including power ascension tests.

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