At 08:33:30 a.m. the Main Steam Isolation Valve (MSIV) no. 20142 on Train B inadvertently closed thus isolating Main Steam Train B. As a result the Train A steam flow increased and the steam pressure dropped below the setpoint for Safety Injection which initiated safety injection and reactor trip. The reactor trip sequence proceeded in accordance with the design, all safety systems were available. The plant was stabilized at "no load" parameters. The first investigation which concentrated mainly on instrumentation and control circuits of the valve revealed no irregularities. In order to mechanically test the valve the reactor was started and the power was increased to 3%. Since the mechanical test was also OK, the plant in accordance with the internal procedures and the decision of the Krsko Operating Committee was allowed to increase power to full power. While performing tests, before the plant was to be synchronized to the grid, operators detected asymmetry in flow and pressure between both steam generators which led them to test the response of the system by alternatively opening and closing the MSIVs. The test discovered that there was no response to the movement of the train B MSIV. Visually the valve stem responded in accordance with the demand but the flow through he valve didn't change. The conclusion was that the valve cylinder was stuck in closed position. The plant was brought to "cold shutdown" and the valve was disassembled. The valve stem was found fractured inside the cylinder. The fractured stem will be sent to the laboratory for analysis. After replacing the stem with the spare one and testing of the valve the plant will resume power operation.
Everywhere you look, the nuclear industry’s hype machine is in overdrive. Goldman Sachs, Microsoft, and the UK government all tout small modular reactors as the silver bullet for climate change and energy security. Tech billionaires are hiring nuclear veterans. Wall Street is whispering about “round-the-clock power” for artificial intelligence data centers. For those old enough […]
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Last year, the Dutch Province of Limburg started an alliance in which, besides the local government, research institutes, small nuclear reactor (SMR) developers, utilities, industrial customers and funders cooperated. With this "Limburg SMR alliance" Limburg tried to lead the way towards an SMR in Limburg. The preferred site for a first SMR would be Chemelot, […]
