Submarine reactor was built from land-based prototype : India

Kalpakkam -, Aug 2 - INS Arihant, India's first indigenously designed and built nuclear powered submarine launched a week ago, is energised by a power pack that was developed from a land-based prototype version, a nuclear scientist revealed here Sunday.

The scientists' team was given the mandate to develop a land-based prototype power pack for a submarine and development and construction of a nuclear steam generating system for the sea-going version,

There is a sea of difference between designing a nuclear power pack to propel a submarine and a land-based atomic power station, Srikumar Banerjee, director of the Bhabha Atomic Research Centre - and member of the Atomic Energy Commission -, told reporters here.

The 82.5 MW nuclear reactor for submarine has been designed here by PRP Centre - PRP originally stood for Plutonium Reprocessing Project - under the BARC.

The PRP Centre is located inside the Kalpakkam nuclear enclave, 45 km from Chennai, housing various atomic energy related entities.

'While a land-based atomic power plant gets support from the grid and others, a nuclear power pack in a submarine does not have such fallback systems,' Banerjee said.

He said the major challenges were miniaturisation of the land-based plant to fit into the confined space of a submarine and also making it lightweight but strong enough to endure the shock due to depth discharge.

'The reactor while withstanding the pitch and roll of a submarine should also be capable of accelerating and decelerating at a quick pace - unlike a land-based power plant which would ramp up speed in a gradual manner,' he added.

To generate power, the steam turbine should be operated at 3,000 revolutions per minute - whereas the nuclear submarine propulsion turbine will be operated at variable speed of 0 to 4,000 rpms.

The reactor designed for a long fuelling cycle time is capable of remaining under water for an extended period, the sortie time being essentially dictated by the endurance of the crew.

The land-based version kept here was conceived and built as a technology demonstrator for the compact pressurised water reactor with a load following capability.

Also known as 'half boat', the entire propulsion plant with primary, secondary, electrical and propulsion systems along with its integrated control was packed in the aft end of the land-based submarine hull designed and built specifically for this purpose.

While in sea the reactor supplies super-heated steam to the propulsion plant to run the submarine, at the PRP Centre the propulsion power is absorbed in the dynamometer which in turn is cooled by sea water.

Banerjee said major components of the submarine reactor were made by domestic industries.

'The reactor vessel is made of special grade steel by Heavy Engineering Corporation, Ranchi, steam generator by Bharat Heavy Electricals Limited -, pressure valves were made by Audco India, Chennai, and others,' he added.

New materials of construction and new technologies were used in building the reactor. The uranium enriched metallic fuel is new too.

There are around 13 fuel assemblies with each assembly having 348 fuel pins.

'It is not just building a nuclear reactor to power a submarine. For us, it is capacity building in the country to get into high technology areas,' said AEC chairman Anil Kakodkar.

PRP facility director Sekhar Basu said the centre will now be the training ground for personnel planning to operate reactors in submarines apart from carrying out research activities.