Large Scale BWR Containment LOCA Response Test at the INKA Test Facility

摘要

KERENA is an innovative boiling water reactor concept with passive safety systems (Generation Ⅲ+) of AREVA. The reactor is an evolutionary design of operating BWRs (Generation Ⅱ). In order to verify the functionality and performance of the KERENA safety concept required for the transient and accident management, the test facility "Integral Teststand Karlstein" (INKA) was built in Karlstein (Germany). It is a mock-up of the KERENA boiling water reactor containment, with integrated pressure suppression system. The complete chain of passive safety components is available. The passive components and the levels are represented in full scale. Only one of the four passive trains of KERENA is installed in the INKA test facility. The volume scaling of the containment compartments is approximately 1:24. This results in an effective volume scaling related to the passive systems of 1:6. The reactor pressure vessel (RPV) is simulated via the steam accumulator vessel of the Karlstein Large Valve Test Facility. This vessel provides an energy storage capacity of approximately 1/6 of the KERENA RPV and is supplied by a Benson boiler with a thermal power of 22 MW. With respect to the available power supply, the containment- and system-sizing the facility is one of the largest test facilities for passive integral system testing ever operated. From 2009 to 2012, single component tests of the passive systems Emergency Condenser, Containment Cooling Condenser, Core Flooding System were conducted. On March 21st, 2013, the first large-scale only passively managed integral accident test of a boiling water reactor was simulated at INKA. The integral test measured the combined response of the KERENA passive safety systems to the postulated initiating event: "Main Steam Line Break" (MSLB) inside the Containment with decay heat simulation. The decay heat was simulated by simultaneous steam introduction and liquid water removal from the pressure vessel. The results of the performed integral test (MSLB) showed that the passive safety systems alone are capable to bring the plant to stable conditions meeting all required safety targets with sufficient margins. Therefore the test verified the function of those components and the interplay between them as response to an anticipated accident scenario. The test provided evidence that the INKA test facility is capable to perform integral system verification tests of passive safety concepts under plant-relevant scaling and plant-like thermodynamic conditions, including the feedback of the accident to the pressure vessel. Being equipped with a state of the art pressure suppression containment INKA is capable to perform also containment response tests for Generation Ⅱ BWRs. Those test results could be used to validate containment response calculation for various LOCA and non- LOCA scenarios. The test could tackle the heat intake and temperature distribution that establishes in the gas and water volume of multi compartment containment or the re-distribution/relocation of non- condensable gases depending on the momentum of the LOCA coolant jet introduced into the containment.