Engineers at the Titan-2 Holding, the construction company tasked with building the third unit at Leningrad Nuclear Power Plant in Russia, recently oversaw the installation of a 120-tonne (132 U.S. tons) core catcher in the reactor containment building. This construction is part of phase II of the Leningrad plant, one of the largest nuclear facilities in Russia. 

With an eye on climate goals, countries are turning back to nuclear energy to meet their energy demands without releasing carbon into the atmosphere. While this is a major shift for other countries, for Russia, it is just a matter of upgrading its nuclear facilities with more powerful home-built reactors. 

The Leningrad Nuclear Power Plant, for instance, is one of the largest power facilities in Russia, providing about 55 percent of the electricity demand in the city of St. Petersburg and the Leningrad region at large. With an installed capacity of 4,400 MWe, the nuclear power plant singlehandedly meets 30 percent of the electricity demand of northwest Russia. 

After over five decades of operation, the original nuclear reactors have been shut down, and their replacement is being built as Phase II of the Leningrad Power Plant. 

Construction in Phase II

The Leningrad Nuclear Power Plant consisted of four RBMK units, one of the earliest Generation II reactors, some of which are still operational elsewhere. At Leningrad, the first two units were shut down in 2018 and 2020, after 45 years of operation each. 

In Phase II, Russia is building VVER-1200 reactors with an estimated service life of 60 years, with a possibility of an extension of another 20 years. This will see the reactors in operation, well beyond the 2080s. The first two units at Leningrad Phase II (Leningrad II-1 and II-2) are commonly known as Units 5 and 6, while the other two units, Leningrad II-3 and II-4, are referred to as Units 7 and 8. 

While Units 3 and 4 at the Leningrad Nuclear Power Plant remain operational, work to replace them has already begun, with concrete pouring for Units 7 and 8 scheduled to start in March 2024 and March 2025, respectively. The core catcher for Unit 7 (Leningrad II-3) was completed recently. 

What is the core catcher? 

Made out of thermally resistant steel, the core catcher is a safety device that springs into action in the event of an emergency. In a situation where the core has melted, the core catcher is designed to hold the radioactive material within the containment of the reactor and not let it spill out. 

Engineers at Titan-2 oversaw the installation of the core catcher into a concrete shaft of the reactor containment building for Unit 7. 

“The likelihood that this passive safety system will ever be truly needed is extremely low,” said Alexey Mochalov, Deputy Chief Engineer for the Construction of New Power Units at Leningrad. 

“All the decisions made in the design of domestic power units with VVER-1200 reactors, the high-quality construction, installation, and commissioning work, as well as the highly qualified and responsible personnel of the nuclear power plant, will leave the trap in standby mode for the entire design life of the unit.”

The construction will now proceed to install the thermal insulation, support and thrust trusses, and other equipment and measuring channels to enable reactor vessel assembly as early as next year.