A significant stage in the construction of Rooppur Nuclear Power Plant (NPP) in Bangladesh was reached earlier this month with the completion of the closing weld that connects the two halves of the reactor pressure vessel (RPV) being manufactured for unit 1 of the NPP.
According to a release by the Russian state nuclear energy corporation Rosatom, the work was undertaken by its machine building division, Atomenergomash, which is the supplier of all the equipment for the reactor compartment of the Rooppur NPP and a significant part of the equipment for the machine room.
The operation lasted for ten days with continuous heating of the weld zone – from 150 to 300 degrees Celsius. During this time, about two tons of flux and more than one and a half tons of wire were used. After welding, the 320-tonne reactor vessel will be heated to 300 degrees and, using a crane, will be transferred to the furnace for two days of heat treatment.
The next stage in the Roopur NPP works will be quality control operations, including x-ray flaw detection, ultrasound and capillary control inspections. Rosatom is building two 1,200 MW VVER-1200 units at Rooppur, which is located on the eastern bank of the river Ganges.
According to another statement, Atomenergomash is manufacturing the internals for the Rooppur RPV, as well as the reactor lid and the upper block, at the company’s Volgodonsk branch.
The core barrel is one of the three main elements of an RPV’s internals. The core barrel vessel consists of six shells and an elliptical bottom. Its height is about 11 meters and it weighs 63 tons.
In the upper part of the core barrel, there are 238 holes with diameter of 196 mm each, besides two holes, each with diameter of 300 mm. The holes are arranged in a specific order of six rows along the perimeter of the shell and are intended as the coolant exits.
There are 1,344 holes of different diameters on the bottom of the product – 40 mm and 60 mm, and there are also 163 holes with diameters of 226 mm. These are intended for supporting the installation and also to protect the fuel assemblies from being injected with small mechanical particles.
The statement added that the next important stage in the Rooppur reactor pressure vessel works will be the installation of the grid and support elements. After the grid and support elements are installed, the test assembly of core barrel with the baffle and protective tube unit will be carried out.