[en] The operation pressure of intermediate loop for 5 MW THR is more 0.2 MPa than the primary circuit. Any equipment in the intermediate loop can be single cut off. By natural circulation, the residual heat removal system removes the residual heat in the core, and it is'nt dependent on other power

[en] The nuclear heating reactor (NHR) was developed by the Institute of Nuclear Energy Technology (INET), Tsinghua University. The main design features and safety concepts of the NHR-200, the criteria and principles that were followed in licensing the construction permit of the NHR-200 are discussed. Licensing activities and procedures are described. Some of the main licensing safety issues including accident analysis, secondary containment design, the requirements for the Diesel generators and the safety classification of systems and components are briefly addressed

[en] The effect of system pressure, heating power, inlet subcooling, and inlet resistance coefficient on the two-phase flow stability and characteristics of two-phase flow instability in a natural circulation system with low pressure and low steam quality were studied on the test loop HRTL-200 using water as coolant, the test pressures are 1.0∼4.0 MPa, heating powers are 27∼240 kW, inlet subcoolings are 5∼80 degree C, and the outlet steam quality is less than 5%. The experimental results show that all of above parameters have effect on the mass flow rate, stable flow region, and vibration characteristics. The experimental study, the rang of whose experimental parameters covered those of the District Heating Reactor 200 MW, helped us to know more about the steam water two-phase flow with low steam quality, and it is also very important for the design and safe operation of the heating reactors

[en] Since the middle of 1980's, a research program on heating reactor has been carried out at Institute of Nuclear Energy Technology (INET) of Tsinghua University in China, the heating reactor is a light water cooled, integral type natural circulation reactor with low system pressure and low core exit quality, it has the passive safety features and other advanced characteristics of the next generation reactors. Because of a relatively long riser and low system pressure, a small quality perturbation at the exit of the core will lead to a relatively large variation of void fraction in the riser, so will the driving force. All of the above features made it very different from the typical PWRs and BWRs. In order to guarantee the safe operation of the heating reactor, a full scale test loop HRTL-200, simulating HR-200 heating reactors in main geometry and operation parameters, was constructed and operated under the broad test conditions covering the 200 MW heating reactor operation conditions at INET. The HRTL-200 test facility, some of steady-state and two-phase flow instability test results from the test facility and the consideration how to choose the optimal design parameters for the heating reactors are shown in this paper. The range of experimentally studied parameters are: the system pressure is from 1.0 to 4.0 MPa, the largest heat flux is about 50 W/cm², and the quality at the exit of the test section is less than 6%. (author)

[en] When a natural circulation system is operated under low pressure and low steam quality, the oscillation behavior of the flow rate of the steam-water mixture in this system is studied. The experimental work was done using water as coolant on the test system HRTL-200 under 1.0-4.0 MPa of pressure, 27-190 kw of heating power, 5-80 degree C of inlet subcooling and less than 5% of outlet steam quality. The range of experimental parameters covers those of the district heating reactor 200 MW. The experimental results about the effect of system pressure, heating power and coolant subcooling on the relevant amplitude of natural circulation flow rate and the oscillation periods are presented

[en] The 5 MW nuclear heating reactor (NHR-5) is the first vessel type heating reactor in operation. Since November 1989 the 5 MW nuclear heating reactor has operated successfully for three years during the winter. A series of experiments and operation tests were carried out during the commissioning and operation periods. The main results of the experiments are given in this paper. It has been shown that the NHR-5 possesses excellent safety characteristics and a high operation availability. (orig.)