Thermal-hydraulic experiments and evaluation for safety features in APR1400

Full text: Thermal-hydraulic experimental program and typical test results for the evaluation or verification of new safety system design features adopted in the APR1400 (Advanced Power Reactor 1400) are presented for major test items. Development of the APR1400, an evolutionary type of pressurized water reactor (PWR), has been completed at the end of 2001 and succeedingly got the approval of its standard design on May 2002. It has a capacity of 4,000 MWth with 2x4 loop arrangement of the reactor coolant system (RCS) and 60 years of design lifetime. APR1400 incorporates many advanced design features to enhance its safety. New design features adopted in the APR1400 include, among others, four trains of the safety injection system (SIS) with DVI (Direct Vessel Injection) mode and passively operating SIT (Safety Injection Tank), the In-containment Refueling Water Storage Tank (IRWST) and the Safety Depressurization/Venting System (SDVS). These new design features has been evaluated to provide significant improvements in the performance and safety, and they are major contributors to the reduced core damage frequency and improved performance against severe accident. Since these new design features, which were not adopted in the existing nuclear power plants, are required to evaluate and verify their performance for ensuring their contribution to the safety enhancement, experimental activities for ensuring their performance and safety enhancement capabilities have started in April 1999 for three years at KAERI under the national nuclear mid and long-term R and D projects. They include the LBLOCA ECCS performance evaluation test for the DVI mode of safety injection, performance verification test of the fluidic device as a passive flow controller and performance evaluation test of the steam sparger for SDVS. Additional experimental work is still on-going focusing on new multi-dimensional thermal-hydraulic phenomena such as DVI line break (SBLOCA) and boron mixing relate to the DVI and thermal mixing and stratification in a large pool related to the IRWST under governmental support (MOST and MICIE). In this paper, the thermal-hydraulic test and evaluation program is presented, which includes the overview, test objectives and experimental and evaluation method, and some of typical test results also are given for each research item. (author)