Russia's TVEL has presented the Czech Republic's Skoda JS with a mock-up of a TVSA-T fuel assembly, an advanced fuel design for VVER-1000 reactors that will replace current fuel at the Temelin nuclear power plant.
A change in fuel is required at Temelin because of recurring deformation problems. Skoda will conduct a serie s of pressure tests on the mock-up replacement fuel assembly, which contains lead pellets instead of uranium pellets. These tests are to be carried out between December 2007 and March 2008 at Skoda's Plsen facility, where tests on the current fuel were carried out.
The four-metre long mock-up assembly, weighing 750 kg, has already passed a full series of mechanical, thermal and hydraulic tests by the Experimental Design Bureau of Machine Engineering (OKBM) in Nizhny Novgorod, Russia. The results of these tests will now be verified by Skoda, which would then apply to the Czech nuclear regulatory authority for a licence to use the fuel.
Following the tests at Pslen, the mock-up assembly will be returned to Russia for a thorough analysis. It will then be delivered later in 2008 to the Temelin plant in order for plant personnel to practice handling the fuel and for control rod drop tests to be conducted.
TVEL was awarded a contract in 2006 to supply fuel for the two VVER-1000 reactors at the Temelin plant. The contract will run for 10 years, during which time TVEL will supply a total of some 400 tonnes of fuel. The first batch of fuel assemblies is expected to be delivered by late 2009 and will be loaded into the reactors in 2010. The fuel will be manufactured at TVEL's Mashinostroitelny Zavod (MSZ) subsidiary in Electrostal, Russia.
TVSA fuel assemblies feature a higher rigidity skeleton compared with standard VVER fuel designs, offering higher operating reliability and resistance to deformations. This strengthened skeleton is formed by spacers and angles joined by spot welding that provide higher rigidity and strength of the structures. The assemblies use uranium-gadolinium fuel. TVSA fuel has been used at Russia's Kalinin nuclear power plant since 1998 and is now used in 16 VVER-1000 reactors in Russia, Ukraine and Bulgaria, representing over 60% of such units in operation.
WNA's Nuclear Power in Czech Republic information paper
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