During the design process of Reactor Coolant Pump (RCP) test circuit, a flow conditioner is considered to be necessary in view of the fact that the RCP test circuit has a large flow volume and a relatively limited space, and it must meet the need of stabilizing the flow as quickly as possible. This article bases on the demands of the function of the flow conditioner in reactor coolant pump test circuit, utilizes the CFD analysis software to carry out 3-dimensioning modeling of several flow conditioners, and simulates the characteristic of the fluid in circuit under different flow conditioners. Through the analysis of the pressure distribution in the downstream of the flow conditioner, different stabilizing effects are obtained, and the final structure of the flow conditioner is determined considering the real demand of the test circuit.

Thermal storage is one of the key technology in the transformation of thermal power flexibility. A model of naturally stratified water storage tank is established, and CFD analysis of heat release process is made. As can be seen from experimental results in a power plant, in the thermocline thickness in the tank increased from 0.43 m to 0.66 m, with an average hourly thickness of 0.06m, which has well agreement with the CFD analysis results. The effective height of the tank is 29.836m, from which we can calculate that its thermal storage efficiency is as high as 96.7%.

Following China’s road map of nuclear technology development, the development of self-reliant nuclear design codes becomes one of the most significant steps in the plan. Among the nuclear design codes, thermal-hydraulic analysis code is indispensable because it is the foundation of reactor safety analysis and reactor design. Recently, China Guangdong Nuclear Power Group has launched a series of R&D projects of reactor design code development. The sub-channel analysis code-LINDEN becomes one of the key subprojects. Since the sub-channel code is developed for thermal-hydraulic design and safety analysis of pressurized water reactors (PWRs), the basic requirements for the LINDEN code are reliability and stability. Therefore, the mathematical model and numerical method developed in the code are based on the matured approaches that have been used in various industrial applications. These models and methods includes: four-equation drift framework model of two-phase flow; the classical heat transfer model and fuel rod model (Poisson equation) as well as the constitutive relations; explicit formulation and stepping algorithms for equation solutions. The solver module of the code is programmed using object-oriented C/C++ language with the structural design.. With all these features, the code was developed to be stable, scalable and compatible. The code’s applicability has been further improved after model improvement and design optimization according to characteristics of China’s proprietary type of reactor. COBRA-IV and LINDEN have been used to conduct the thermal-hydraulics analysis for the Daya bay unit 1 and 2 nuclear plants at the steady-state conditions. The results demonstrate that the two codes agree well with each other. The preliminary tests show that the LINDEN code should be suitable for thermal-hydraulics analysis of large PWRs.

Small Modular Reactor has gained much attention in recent years. The passive residual heat removal system (PRHRS) is designed to increase the inherent safety features of the Integral Small Modular Reactor. There are many differences on the design of PRHRS. To get a comprehensive understanding of the PRHRS design in ISMRs, two simplified simulation models of ISMRs with different PRHRS design are built by the use of thermal hydraulic system code Relap5/Mod3.2 in this paper. A blackout accident is introduced to study the different performance between two PRHRS design models. The calculation results show that both two cases can successfully remove decay heat from the core. But there are still some differences between two cases in aspects of primary and PRHRS coolant parameters. Comparisons of the results from two cases are conducted in this paper, and the differences are carefully analyzed too.

Small modular reactor is investigated worldwide with the advantages of lower initial investment and short construction period. Generally, the economy of small modular pressurized water reactor (PWR) is not as good as large PWR, so various applications of small PWR are investigated, such as marine reactor, heat supply and sea water desalination. Limited to the parameters of steam generator, the generating efficiency for the pressurized water reactor nuclear power plant is about 33%, while the steam temperature of supercritical fossil power plant can exceed 600°C and generating efficiency is more than 45%. The essence of a hybrid power plant is to use a fossil fuel to superheat wet steam in an outer steam superheating device, after the steam generator to improve the parameters of working fluid. On one hand, the innovative hybrid nuclear power plant which combines nuclear reactor with conventional thermal energy can improve the efficiency of small PWR. On the other hand, this hybrid power plant has lower carbon emission compared with traditional thermal power plant. This paper describes two different coupling schemes of small pressurized water reactor combined with supercritical thermal power plant using steam turbine. Efficiency of hybrid power plant is influenced by the coupling scheme, steam parameter of the superheating device outlet, the proportion of nuclear energy, efficiency of assemblies and so on. The plant efficiency becomes higher with the improvement of parameter of the superheating device’s outlet steam, and it is higher when the proportion of nuclear energy becomes lower. Take the 660MWt integrated small pressurized water reactor as an example, when the proportion of nuclear energy accounts for 48%, the thermal efficiency of this innovative hybrid power plant is about 43%,while the net efficiency is 41%, that is much higher than the efficiency of traditional pressurized water reactor, improving about 24 percent. As to the carbon emission, it depends on the coal consumption rate of power supply. The coal consumption rate of this hybrid power plant is 158g /kWh, while the consumption rate of thermal hybrid power plant is 280g/kWh, reducing about 44 percent. Also, the fundamental solutions of technical problems for this innovative hybrid power plant are discussed in the paper. Furthermore, several useful outcomes and suggestions for key equipments are put forward, such as the scheme of a superheating device and high-temperature steam turbine, and the possibility of using a lava boiler as the superheating device to improve the steam parameters after the steam generator is analyzed.