Safety of the valves in the nuclear power industry
The condition is a qualified supplier
It is not easy to become a member of elite group of qualified suppliers for nuclear power. First, it is necessary to qualify the selected equipment for demanding conditions. That means that this product must fulfil the strictest standards about possible seismic action of group 1a. They need to ensure safe functionality after the quake, resist to considerable vibration in working conditions and meets the parameters to comply with the specified hydraulic losses. It must guarantee specified number of cycles throughout its lifetime at full working parameters. Many other requirements are tested in practice in different types of accredited testing room in Czech Republic and abroad. Only in case of positive results follow the supplier qualification, which is additionally also specific in different countries.
The pressure on safety operation of nuclear power plant became even higher after the nuclear disaster in Japan in nuclear power plant Fukushima Daiichi. This disaster caused the process of strict controls and implementing several new measures, related to the requirements of new safer emergency systems. The measures were also made in the Czech Republic, which operates two nuclear power plants VVER with six blocks. Operator ČEZ a.s. ordered the development and approval of many new projects, which goal was to increase the safety of the power plant associated with the planned extension of the service life of all operated blocks.
Projects for safer operation
One of those projects are new systems of lowering the pressure in gas tanks, which allow the back transfer of the content from gas tank to the hermetic zone in case of trial or real disaster with special request on LOCA test. LOCA disaster is one of the most serious disaster associated with the lost of coolant accident, where the main supply pipeline can break and thus cause overheating and subsequent fuel melting associated with high radiation.
ARMATURY Group’s supply of valves for nuclear power
ARMATURY Group succeeded in a tender for supplier of butterfly valves AL32 and check valves AC09 thanks to experiences and proven quality of supply of the valves for nuclear power. “Our success was caused due to good preparation and cooperation with ÚJV Řež, which assessed all documentation from our previous testing and used materials especially degrading under the radiation and many other requirements, such as requirements for seismic and vibration resistance, EMC compatibility and especially safe operation in the case of possible LOCA event,” says Rostislav Šárovský, sales manager for nuclear power. Thanks to this qualification ARMATURY Group was selected as supplier.
Many companies from nuclear energy sector were participating in this tender. Most of them did not have the qualification or they failed to complete it. “First part of the delivery is planned in November of this year. Quality plan is approved, so there is nothing in the way to complete the supply in the request quality and time” continues Šárovský.
The biggest success of ARMATURY Group in the recent period is the replacement of gate valves Persta at nuclear power plant Temelín with new gate valves AS33 AG DN 600, which had better results than expectation of the operators of the cooling service water. After reconstruction, big water shocks from the pipeline disappear and during opening the gate valves the present operators were in doubts, whether they triggered the command for the valves to operate.
From our successful supplies of ARMATURY Group we can name for example the delivery of huge butterfly valves L32 AG DN 2600 – two tandems with assembling insert for the main pipeline from cooling tower to the nuclear power plant and many others “smaller” diameters of butterfly valves (DN 600-2200), which are gradually replacing old types of valves.
And service again!
We must not forget to mention the quality of service. The service department of ARMATURY Group has huge experience and good references in demanding working conditions. The last success is the reconstruction of power station Hněvkovice for nuclear power plant Temelín, where the company performs services to valves also from different suppliers and gradually replaces them with own production, such as in case of delivery of ball valve DN 1400.
In Dukovany, we do practically the whole service on cooling systems and valves of bigger diameters, which we also gradually replace with valves of our production. Our company has positive feedback, especially due to the service,” closes Šárovský.
Rostislav Šárovský, sales manager for nuclear power.