Russian firm Rosatom has begun welding of the upper semi-vessel of the reactor pressure vessel, or RPV, for Unit-2 of Rooppur Nuclear Power Plant (RNPP) in the Volgodonsk branch of 'AEM-technology' in Russia.

Following test assembly of components of the RPV semi-vessel, two shells and a flange of it were put together, said Triune, the local representative of Rosatom, on Friday.

With the help of a crane, they were lifted to a welding stand for welding under heating at a temperature of 150-300 degrees celsius. It was then heated up to 300 degrees in the welding zones.

With the help of a bridge crane with a lifting capacity of 180 tonnes, it was moved into the furnace to conduct HT for four days.

Simultaneously, manufacturing of lower semi-vessel consisting of three shells and a bottom was in progress.

The reactor represents a vertical cylindrical body with an elliptical bottom. It hosts the core and the internals.

On top, it is sealed with a cover with drives mechanisms and regulating devices installed on it for the protection of the reactors. It has nozzles, intended for passage of sensor cables of conducting in-core monitoring.

In the upper part of the vessel, there are nozzles for the coolant input and output, as well as nozzles for emergency supply of the coolant if the circuit is depressurised.

The RNPP is designed and being built according to the Russian project.

The plant will have two power units each with a capacity of 1200-megawatt (MW). Each unit will host a generation 3+ VVER-1200.

AEM-technology is a part of Atomenergomash, engineering division of Russia's state-owned atomic energy corporation - Rosatom.

The Rooppur plant is being built under a supplier's credit deal with Russia.

The Russian Bank for Development and Foreign Economic Affairs and Bangladesh's state-owned Sonali Bank Ltd will work as authorised banks for the state loan.

The Bangladesh government will also provide Tk 220.52 billion of its own funding for the project.

Atomenergomash, the engineering division of Rosatom and parent company of AEM Technology, is a single source supplier of all equipment of the reactor compartment of the Rooppur nuclear plant. A different division of Rosatom is manufacturing the reactors, steam generators, pumping and heat exchange equipment for the Rooppur plant.

The expected commissioning of Rooppur-1 has already been deferred by one year to 2023, from 2022.

Work for the preparatory phase of the Rooppur plant is nearing completion and the main construction is expected to begin in the second half of the current year, Rosatom said in an earlier statement.