Korea Hydro & Nuclear Power to Replace Hydrogen Explosion Prevention Devices in 18 Nuclear Reactors Failing to Meet Standards

Nuclear Safety Commission Approves Replacement of PAR Devices
Korea Hydro & Nuclear Power to Swap Out Ceracom Units for KNT Equipment
Shin-Wolsong Reactor Leak Test Cycle Extended to 10 Years

Choi Wonho, Chairman of the Nuclear Safety and Security Commission (center in photo), is discussing agenda items with commissioners at the 220th meeting of the Nuclear Safety and Security Commission held on the 28th in the main conference room of the Nuclear Safety and Security Commission in Jung-gu, Seoul. Nuclear Safety and Security Commission

Korea Hydro & Nuclear Power has decided to replace the hydrogen explosion prevention safety devices (PARs) installed in 18 operating nuclear power plants.

On August 28, the Nuclear Safety Commission held its 220th meeting and deliberated and approved the operational change permit requested by Korea Hydro & Nuclear Power for 18 nuclear reactors and Shin-Wolsong Units 1 and 2, as well as the business change permit requested by Korea Nuclear Fuel.

Previously, Korea Hydro & Nuclear Power applied for an operational change permit to revise the Final Safety Analysis Report and the operating technical guidelines for the replacement of PARs in 18 reactors (Kori Units 2 to 4, Wolsong Units 2 to 4, Hanbit Units 1 to 6, Hanul Units 1 to 6).

The PAR is a safety device that prevents nuclear plant explosions by reducing hydrogen concentration in the air inside the reactor containment building during disaster situations when electricity is not supplied to the plant. If reactor cooling becomes impossible due to various disasters, the nuclear fuel rods submerged in water undergo a chemical reaction with water, generating hydrogen. The 2011 Fukushima nuclear accident was caused by a hydrogen explosion. In South Korea, after the Fukushima accident, PAR equipment capable of removing hydrogen even without electricity was widely installed.

However, in 2023, the Nuclear Safety Commission received a public report stating that the PAR equipment used in 18 domestic nuclear reactors performed at only half the level claimed by the manufacturer. Domestic nuclear power plants use PARs from Ceracom, KNT, and AREVA, but the report indicated that Ceracom's performance did not meet the required standards.

After receiving the report, the Nuclear Safety Commission tested the hydrogen removal rate of the PARs. Interim test results at that time showed that Ceracom's PARs removed hydrogen at a rate of only 0.131 to 0.137 grams per second (at a hydrogen concentration of 4%), falling short of Korea Hydro & Nuclear Power's purchase specification (0.2 grams per second) and Ceracom's claimed performance (0.251 grams per second).

As a result, Korea Hydro & Nuclear Power applied for an operational change permit to replace Ceracom's PAR equipment with devices from KNT. KNT's PARs were evaluated to remove hydrogen at a rate of 0.23 to 0.28 grams per second under the same conditions.

With the Nuclear Safety Commission's approval of the operational change permit, Korea Hydro & Nuclear Power plans to replace 50 Ceracom PAR units with KNT equipment.

The Nuclear Safety Commission also approved a revision to the operating technical guidelines (TS) to extend the integrated leak rate test (ILRT) cycle for the reactor containment buildings of Shin-Wolsong Units 1 and 2 from the current 5 years to 10 years.

This content was produced with the assistance of AI translation services.