The recently operational third unit of the Kakrapar Atomic Power Project (KAPP-3) in Tapi district, Gujarat has attracted much attention. This new powerhouse is the first to achieve a state known as ‘criticality’ in India’s pursuit of atomic power advancement.
Achieving Criticality
Criticality refers to the initial phase in power production within a nuclear reactor. In simple terms, a reactor is deemed critical when the nuclear fuel sustains a fission chain reaction. This reaction releases enough neutrons to allow a series of self-sustaining reactions. This process generates substantial heat, which is converted into steam. The steam propels a turbine that ultimately produces electricity.
The fission reaction, characteristic for nuclear reactors, occurs when an atom’s nucleus divides into two or more smaller nuclei, producing a significant amount of kinetic energy. This energy is transferred, as heat, to fuel atoms and eventually contributes towards steam production driving turbines.
Significance of KAPP-3
KAPP-3 is a milestone in India’s atomic power projects, taking the title as the country’s first 700 MWe (megawatt electric) unit. This powerhouse is the largest indigenous version of the Pressurized Heavy Water Reactor (PHWR). The PHWR concept utilizes unenriched natural uranium as its fuel and applies heavy water (deuterium oxide D2O) as a coolant and moderator. Until now, the biggest indigenous reactor was a 540 MWe unit deployed in Tarapur, Maharashtra.
The state-owned Nuclear Power Corporation of India Ltd (NPCIL) commissioned the construction of both KAPP-3 and 4 back in 2010. This marks almost a half-century journey since India commenced efforts to develop PHWR technology with the building of a 220 MWe reactor, Rajasthan Atomic Power Station (RAPS-1) in the late 1960s.
Advanced Safety Features of KAPP-3
The 700 MWe PHWRs, such as KAPP-3, are equipped with enhanced safety features. These include a steel lined inner containment, a passive decay heat removal system, a containment spray system and a hydrogen management system, among others. The passive decay heat removal system is designed to eliminate decay heat (emitted from radioactive decay) from the reactor core without requiring human intervention. This safety measure mirrors those adopted for Generation III+ plants to prevent a Fukushima-type accident from occurring.
The Influence of KAPP-3
KAPP-3 addresses the issue of excess thermal margins, referring to how much below its maximum operating temperature the reactor operates. It signifies a significant element in India’s nuclear power capacity expansion plan, primed to boost existing 6,780 MWe nuclear power capacity to 22,480 MWe by 2031.
Currently, nuclear power accounts for less than 2% of India’s total installed capacity of 3,68,690 MW (as of end-January 2020). With the successful operation of KAPP-3, future construction of PHWRs will be empowered, enhancing this percentage.
Nuclear Power Corporation of India Limited
The Nuclear Power Corporation of India Limited (NPCIL) is an Indian public sector enterprise residing in Mumbai and wholly owned by the Government of India. NPCIL is responsible for generating nuclear power for electricity and is managed by the Department of Atomic Energy (DAE).
