John Thompson’s Utility Boilers & Environmental (B&E) business unit has been awarded a contract to perform all the welding work involved in the replacement of the steam generators at Koeberg nuclear power station near Cape Town.
The steam generator replacement project, involving removal of the original steam generators and replacing them with brand new generators, forms a major part of a R20-billion programme being undertaken by Eskom to extend Koeberg’s life by a further 20 years.
The six new steam generators, delivered to Koeberg in late September and early October this year, were manufactured and supplied by Framatome, a leading international designer and manufacturer of nuclear equipment. Each generator weighs about 380 t and is 20 m long.
Koeberg’s existing steam generators, which were installed in the early 1980s when the nuclear plant was under construction, were also produced by Framatome.
Framatome will remove the existing steam generators and will install the new generators in their place, while contracting John Thompson’s B&E unit to remove all the existing piping and replace it with special steel piping imported from Europe. The B&E unit’s contract involves welding of primary piping between the nuclear reactors and the new steam generators and secondary piping between the steam generators and the turbines.
The changeover operations at Koeberg’s two generating units will be performed during two shutdowns next year, each lasting several months. One of the units is scheduled to shut down in February and the other in September, with three steam generators being installed in each unit.
The company, based in Kempton Park, Gauteng, is the only welding contractor in South Africa with RD 0034 Level 1 status, representing official recognition by the National Nuclear Regulator of its competency to perform welding work in accordance with the stringent safety and quality standards applicable to nuclear power plants. The B&E unit is also the first South African operation of its kind to be commissioned to undertake such a contract.
“We have extensive experience with welding of main steam piping from boilers to turbines in coal-fired power stations, which is exactly equivalent to the work our welders will be required to perform in the present contract,” commented Herman Steyn, the B&E unit’s Nuclear Department Manager. Up to 30 highly skilled welders employed by the unit will perform the welding involved and the unit will deploy in excess of 100 people on site at peak times during the shutdowns.
All personnel engaged on the contract are required to undergo intensive safety training before being permitted to enter the Koeberg plant. Nuclear safety is in many respects different and more rigorous than the safety rules and procedures that are followed in other industries, due to the unique radiation hazards and dangers workers can be exposed to in a nuclear environment.
“The procedures we adhere to are in accordance with the Nuclear Safety Culture adopted by the International Atomic Energy Agency in the late 1980s following the Chernobyl nuclear disaster in 1986,” said Herman.
“In the Nuclear Safety Culture and the integrated management system that forms part of it overriding priority is given to safety over all other issues. What this amounts to is that the Nuclear Safety Culture is far more than a set of rules and procedures to be followed – it is a way of life that people working in a nuclear environment have to be conscious of at all times while attending to their work,” he emphasised.