Installation of the inner and outer parts of steel structures of the passive heat removal system (PHRS) deflector at unit 2 of the Rooppur NPP under construction in Bangladesh was completed in two days according to general designer and general contractor ASE JSC (part of Rosatom).
The complexity of this two-stage operation was that the maximum allowable deviation during installation of heavy steel structures weighing 135 and 80 tonnes on a spherical surface is 10 mm. Following installation of the inner and outer parts of the deflector in the design position at elevation 64.5 metres, the height of reactor building reached 74.85 metres.
In terms of design, the deflector is a metal cylinder made of stainless steel, with the weight of 215 tonnes and the diameter about 25.5 metres. The work involved two lead geodetic engineers, a team of five highly qualified welders and 42 installers of steel structures.
“Installing two parts of PHRS deflector in the design position in two days is a record, said Alexey Deriy, ASE JSC Vice President and Director of the Rooppur NPP construction project. The next step is installation of steel structures of PHRS deflector service platforms and installation of air ducts of the passive heat removal system.”
The PHRS deflector is an aerodynamic structure designed to augment thrust in the ventilation channel and to increase efficiency of the ventilation system. Operation of the entire system is based on natural circulation: the atmospheric air comes into heat exchangers, is heated up, then it rises through air ducts to the outlet header located on top of the dome, and returns to the atmosphere, thus cooling down the reactor compartment. The advantage of passive heat removal is that it can operate using permanent natural processes, without requiring operator involvement or a power supply.
The Rooppur plant is being built by Rosatom on the eastern bank of the Ganges River in Bangladesh’s Pabna district, about 160 km northwest of Dhaka. It will comprise two VVER-1200 reactors. In November 2011, Russia and Bangladesh signed an inter-governmental agreement on cooperation in the construction of the NPP and in mid-December 2015, a general contract was signed. Construction began in 2021. Construction of the unit 1 began in November 2017 and unit 2 in July 2018. The plant’s design life is 60 years with the possibility of extending its operating life for another 20 years. Fresh fuel for the units was delivered to the site in the latter part of 2023.
Image: The structure sits on top of the reactor building (courtesy of Rosatom)
