Simulation of Spray Injection in the Pressurizer Using RELAP5

A modeling research using Relap5 to assess the pressurizer of a pressurized water reactor(PWR) power plant has been performed. The heater and water injection systems in the pressurizer system of the PWRare of greatimportance for system pressure control.The heater is designed to increase the pressure while the water sprayer injection is to perform depressurization. Most of studies conducted in the past mainly focused on determining the effects of nozzle spray design and droplet size using testing loops. The purpose of this simulation is to analyze the spray injection flow rate against the pressure characteristics of the pressurizer using RELAP5. Through this approach, the optimum injection flow rate of full scale plant pressurizer can be analyzed. The parameters investigated are pressure and temperature.In RELAP5, the pressurizer tank wasmodeled with six volume nodes and the heater was modeled by using heat structure. In the model, the sprayer takes water from the cold leg to inject it into the top of tank region.The resultsshowedthat the mass flow of about 4 kg/s is the mosteffectivevalueto limit pressure in the pressurizer to below 15.7 MPa. However, the flow rates of 8 kg/s and more cause overpressure. This simulation is usefulto complement the data related to the water flow rate injection systems of the pressurizer

Simulation of Spray Injection in the Pressurizer Using RELAP5

A modeling research using Relap5 to assess the pressurizer of a pressurized water reactor(PWR) power plant has been performed. The heater and water injection systems in the pressurizer system of the PWRare of greatimportance for system pressure control.The heater is designed to increase the pressure while the water sprayer injection is to perform depressurization. Most of studies conducted in the past mainly focused on determining the effects of nozzle spray design and droplet size using testing loops. The purpose of this simulation is to analyze the spray injection flow rate against the pressure characteristics of the pressurizer using RELAP5. Through this approach, the optimum injection flow rate of full scale plant pressurizer can be analyzed. The parameters investigated are pressure and temperature.In RELAP5, the pressurizer tank wasmodeled with six volume nodes and the heater was modeled by using heat structure. In the model, the sprayer takes water from the cold leg to inject it into the top of tank region.The resultsshowedthat the mass flow of about 4 kg/s is the mosteffectivevalueto limit pressure in the pressurizer to below 15.7 MPa. However, the flow rates of 8 kg/s and more cause overpressure. This simulation is usefulto complement the data related to the water flow rate injection systems of the pressurizer

Design Safety Considerations for Water Cooled Small Modular Reactors Incorporating Lessons Learned from the Fukushima Daiichi Accident

The global future deployment of advanced nuclear reactors for electricity generation depends primarily on the ability of nuclear industries, utilities and regulatory authorities to further enhance their reliability and economic competitiveness while satisfying stringent safety requirements. The IAEA has a project to help coordinate Member State efforts in the development and deployment of small and medium sized or small modular reactor (SMR) technology. This project aims simultaneously to facilitate SMR technology developers and potential SMR users, particularly States embarking on a nuclear power programme, in identifying key enabling technologies and enhancing capacity building by resolving issues relevant to deployment, including nuclear reactor safety. The objective of this publication is to explore common practices for Member States, which will be an essential resource for future development and deployment of SMR technology. The accident at the Fukushima Daiichi nuclear power plant was caused by an unprecedented combination of natural events: a strong earthquake, beyond th e design basis, followed by a series of tsunamis of heights exceeding the design basis tsunami considered in the flood analysis for the site. Consequently, all the operating nuclear power plants and advanced reactors under development, including SMRs, have been incorporating lessons learned from the accident to assure and enhance the performance of the engineered safety features in coping with such external events. In response to the Fukushima Daiichi accident, the IAEA established an Action Plan on Nuclear Safety. The preparation of this publication was carried out within the framework of the IAEA Action Plan on effectively utilizing research and development. The main objective of this publication is to present technology developers and user s with common considerations, approaches and measures for enhancing the defence in depth and operability of water cooled SMR design concepts to cope with extreme natural hazards. Indicative requirements to prevent such an accident from recurring are also provided for States planning to adopt water cooled SMR designs and technologies. The IAEA gratefully acknowledges the information on technology and safety aspects provided by SMR design organizations and information regarding technical requirements provided by several Member States. The IAEA officers responsible for this publication were M.H. Subki of the Division of Nuclear Power and M. Kim of the Division of Nuclear Installation Safety

Simulation of Spray Injection in the Pressurizer Using RELAP5

A modeling research using Relap5 to assess the pressurizer of a pressurized water reactor(PWR) power plant has been performed. The heater and water injection systems in the pressurizer system of the PWRare of greatimportance for system pressure control.The heater is designed to increase the pressure while the water sprayer injection is to perform depressurization. Most of studies conducted in the past mainly focused on determining the effects of nozzle spray design and droplet size using testing loops. The purpose of this simulation is to analyze the spray injection flow rate against the pressure characteristics of the pressurizer using RELAP5. Through this approach, the optimum injection flow rate of full scale plant pressurizer can be analyzed. The parameters investigated are pressure and temperature.In RELAP5, the pressurizer tank wasmodeled with six volume nodes and the heater was modeled by using heat structure. In the model, the sprayer takes water from the cold leg to inject it into the top of tank region.The resultsshowedthat the mass flow of about 4 kg/s is the mosteffectivevalueto limit pressure in the pressurizer to below 15.7 MPa. However, the flow rates of 8 kg/s and more cause overpressure. This simulation is usefulto complement the data related to the water flow rate injection systems of the pressurizer. Normal 0 false false false EN-US X-NONE X-NONE <![endif]-

The Analysis of Loss of Forced Flow Event on the HTGR Type Experimental Power Reactor

Since 2014, Indonesia's National Atomic Energy Agency (BATAN) has been launching a plan to construct a 10 MWt Experimental Power Reactor (Reaktor Daya Eksperimental / RDE). The RDE design is based on the small-sized pebble-bed high-temperature gas-cooled reactor (HTGR) technology with TRISO fuels. By concept, HTR-10 design, which was developed by the INET of China, is used as the reference design. During the development process, a safety analysis report (SAR) of RDE design has to be prepared to be evaluated by the Indonesia Nuclear Regulatory Agency (BAPETEN). The report contains, among others the description of the RDE accident sequences, which can be only provided by simulations using a certain code. This paper emphasizes the transient analysis, which is simulated using RELAP5/SCDAP/Mod3.4 , which is a thermal-hydraulic code specified for light water coolant systems. The simulated event is the loss of primary coolant mass flow, which is caused by the failure of the primary gas blower motor. The methodology of simulation is first by modelling the RDE nuclear steam supply system to verify steady-state operational parameter of the RDE design. The second step is to simulate the event of loss of flow, which is followed by the failure to shut down the reactor. The simulation results in the decrease of the fuel pebble temperature during the event due to the negative fuel temperature reactivity coefficient and the core heat removal by the cavity cooling. Overall, the RELAP5 code has a limitation in the RDE simulation to define two different non-condensable gases, which reduces the accuracy of the simulation results