‘Core catcher’ safety device installed in unit 5 of India’s Kudankulam nuclear plant

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The core catcher has been installed in the under construction fifth unit of the Kudankulam nuclear power plant (KNPP) located in India’s Tamil Nadu state, according to a statement last week by the Russian state atomic energy corporation, Rosatom.  

The core catcher is an essential part of the nuclear plant’s safety system ensuring prevention of radiation leakage into the environment in case of a severe accident “beyond design-basis”, causing destruction of the reactor vessel. 

“Power unit No. 5 of the Kudankulam NPP constructed in India under the Russian VVER-1000 reactor-type NPP design saw the first component of the nuclear reactor core melt localization device (CMLD, core catcher), an essential part of the prevention system ensuring the safety of beyond-design-basis accidents, installed in the design position,” the statement said. 

Rosatom is the equipment supplier and technical consultant for the KNPP, India’s largest nuclear plant operated by the state-run Nuclear Power Corporation of India. Its units 1 and 2 of 1,000 MW capacity each, started commercial operations in 2014 and 2016, respectively. The construction is underway of four more units at Kudankulam – 3, 4, 5 and 6 – also of 1,000 MW capacity each.      

The core catcher, installed on supports under the reactor vessel, is made as a globe-bottom container that weighs more than 156 tonnes. The total weight of the entire device exceeds 800 tonnes. Apart from a casing, the main CMLD components include cartridge units filled with special non-metallic material, maintenance platform, cantilever truss, and a bottom plate, the statement said.  

As part of preparations for the core catcher installation, a significant amount of work was completed, including the placement in the melt localisation pit of the second concrete layer and sealing liner, installation in the pit of an embedded part, and concreting of the reactor cavity, the statement added.  

“It brought us an exceptional pleasure when, during expert discussions currently taking place at the construction site, the Indian party invited all participants to come to a large window and to observe the catcher being raised before the installation,” Rosatom subsidiary Atomstroyexport’s Director of Indian Projects, Mikhail Novikov, said in a statement.  

According to Rosatom, the core catcher invented by the company can contain liquid and solid fragments of the core and structural materials of the reactor for an indefinitely long time, keeping a nuclear power plant safe for the environment and people. 

Earlier this year, the reactor pressure vessel, the pressuriser, and four steam generators for the fifth unit of the Kudankulam nuclear power plant were shipped from Russia.   

A trial assembly of the internals of the reactor pressure vessel was undertaken in January this year at the company’s Volgodonsk plant in Russia. The trial assembly, in which the products completely replicate their design position, significantly reduces the time taken to install the reactor at the nuclear plant construction site and simplifies the process of its installation too.