38. High temperature magnetic filtration of crud from primary circuit coolant of BWRs

1978 ◽  
pp. 341-349
Author(s):  
K. Harding
Keyword(s):  
High Temperature ◽  
Primary Circuit ◽  
Magnetic Filtration

scholarly journals Design of the Online Gross γ Monitoring Instrument at the Exit of the Helium Purification System in HTR-PM

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Mengqi Lou ◽  
Liguo Zhang ◽  
Feng Xie ◽  
Jianzhu Cao ◽  
Jiejuan Tong ◽  
...  
Keyword(s):  
High Temperature ◽  
Detection Efficiency ◽  
Primary Circuit ◽  
Source Terms ◽  
Primary Loop ◽  
Monitoring Instrument ◽  
Purification System ◽  
Design Values ◽  
Under Construction ◽  
High Temperature Gas

After the successful construction and operation experience of the 10 MW high-temperature gas-cooled reactor (HTR-10), a high-temperature gas-cooled pebble-bed modular (HTR-PM) demonstration plant is under construction in Shidao Bay, Rongcheng City, Shandong province, China. An online gross γ monitoring instrument has been designed and placed at the exit of the helium purification system (HPS) of HTR-PM and is used to detect the activity concentration in the primary circuit after purification. The source terms in the primary loop of HTR-PM and the helium purification process were described. The detailed configuration of the gross γ monitoring instrument was presented in detail. The Monte Carlo method was used to simulate the detection efficiency of the monitoring system. Since the actual source terms in the primary loop of HTR-PM may be different than the current design values, a sensitivity analysis of the detection efficiency was implemented based on different relative proportions of the nuclides. The accuracy and resolution of the NaI(Tl) detector were discussed as well.

Study on Heating Process of Dehumidifying Experiment in HTGR

2020 ◽  
Author(s):  
Kaiyue Shen ◽  
Wei Zheng ◽  
Shengchao Ma ◽  
Huaqiang Yin ◽  
Xuedong He ◽  
...  
Keyword(s):  
High Temperature ◽  
Kinetic Energy ◽  
Thermal Energy ◽  
Reactor Core ◽  
Primary Circuit ◽  
Heating Process ◽  
Transfer Model ◽  
Thermal Source ◽  
Flow And Heat Transfer ◽  
Selection Of

Abstract A large number of carbon materials are used in high temperature gas-cooled reactor (HTGR). As a kind of porous material, the carbon material contains a certain amount of moisture and other impurities. In order to reduce the corrosion of internal material in reactor core of HTGR, the initial core or post-accident core must be strictly heated and dehumidified. The current primary circuit heating mainly relies on the rotation of the primary pump to convert the kinetic energy into thermal energy. Obviously, the current scheme was flawed: (1) Due to the insufficient heat generated by rotation of the primary pump, the temperature rising process of the primary circuit is sluggish; (2) The rotation of the primary pump converts the kinetic energy into thermal energy of the helium, at the meantime, the primary circuit dissipates heat outward. For the above reasons, it is difficult to achieve the desired dehumidification temperature in the heating process. While in this paper, an additional thermal source will be added to the steam generator to heat the primary circuit in a new scheme. A proper flow and heat-transfer model of heating the primary circuit in high-temperature reactor was established based on software COMSOL Multiphysics. The numerical analysis of the primary circuit heating process provides rewarding guidance for the selection of the dehumidification scheme in HTGR.

Polycrystalline Diamond Films as Protection of Zircaloy Fuel Cladding

2014 ◽  
Author(s):  
Jan Škarohlíd ◽  
Radek Škoda
Keyword(s):  
High Temperature ◽  
Ion Beam ◽  
Cooling Water ◽  
Chemical Vapor ◽  
Polycrystalline Diamond ◽  
Zirconium Alloys ◽  
Carbon Layer ◽  
Primary Circuit ◽  
Temperature Oxidation ◽  
Diamond Layer

Polycrystalline diamond coating is a promising possibility for prevention, or reduction of high temperature oxidation of zirconium alloys. Zirconium alloys are used as cladding material in almost all types of nuclear reactors, where creates a barrier between nuclear fuel and cooling water in the primary circuit. Hydrogen and considerable amount of heat is released during steam oxidation that may occur in an eventual accident. In this paper Zircaloy-2 alloy was covered by polycrystalline diamond layer using Plasma Enhanced Linear Antennas Microwave Chemical Vapor Deposition system reactor. X-Ray Diffraction and Raman spectroscopy measurements confirmed coverage of the surface area with crystalline and amorphous carbon layer. Characterizations were done for zirconium alloy covered with diamond layer before and after corrosion and irradiation tests - ion beam irradiation tests and high temperature steam exposure.

The Water Ingress Mass Analysis on Steam Generator Heat-Exchange Tube Rupture Accident of High Temperature Gas-Cooled Reactor

2009 ◽  
Author(s):  
Yan Wang ◽  
Yanhua Zheng ◽  
Fu Li ◽  
Lei Shi ◽  
Zhiwei Zhou
Keyword(s):  
High Temperature ◽  
Heat Exchange ◽  
Steam Generator ◽  
Mechanical Load ◽  
Radioactive Isotopes ◽  
Primary Circuit ◽  
Secondary Circuit ◽  
Water Ingress ◽  
Heat Exchange Tube ◽  
High Temperature Gas

The module high temperature gas-cooled reactor (HTGR) is an advanced reactor with high safety level. The steam generator heat-exchange tube rupture (SGTR) accident (or water ingress accident) is an important and particular accident which will result in water ingress to the primary circuit of reactor. Water ingress may, in turn, result in chemical reaction of graphite fuel and structure with water, causing release of radioactive isotopes and generation of explosive gaseous in large quantity. The analysis of SGTR is significant for verifying the inherent safety characteristics of HTGR. One of the key factors is to estimate the amount of water ingress mass which is used to evaluate the severity of the accident consequence. The 200MWe high temperature gas-cooled reactor, which is designed by the Institute of Nuclear and New Energy Technology of Tsinghua University, is selected as an example to analyze. The accident scenarios of double-ended rupture of both single and two heat-exchange tubes at the inlet and outlet of steam generator are simulated respectively by RETRAN-02. The results show that the amount of water ingress mass is related to the break location, the number of ruptured tubes (or the break size). The greater the number of ruptured tubes or the break size, the larger the amount of water ingress mass. It is important to design the draining pipe line with reasonable diameter, which should be optimized based on economy and safety considerations for preventing large water ingress to the reactor primary circuit, restricting the change rate of mechanical load on SG, and reducing the radioactive isotopes release to the secondary circuit.

First-Principles Studies of Diffusion Behaviors of Tritium in HTR-PM Materials: From Framework to Preliminary Result

2018 ◽  
Author(s):  
Chao Fang ◽  
WenYi Wang ◽  
HongYu Chen ◽  
Chuan Li
Keyword(s):  
Activation Energy ◽  
High Temperature ◽  
Ab Initio ◽  
Source Term ◽  
Minimum Energy ◽  
Diffusion Path ◽  
Diffusion Activation Energy ◽  
Primary Circuit ◽  
Secondary Circuit ◽  
Diffusion Behaviors

High Temperature Reactor-Pebblebed Modules (HTR-PM) is a typical high-temperature gas cooled reactor (HTGR) [1]. Tritium is one of the most important radionuclides in reactors owing to its very harmful β-radiation and long half-life. In the HTR-PM, Silicon carbide (SiC) is the main barrier of triisotropic (TRISO) particles to prevent the diffusion of Tritium into the primary circuit [2]. When Tritium into the primary circuit and circulate to Steam Generator (SG), the Incoloy800H alloy is another important material to prevent the diffusion of Tritium into the secondary circuit [3]. When analyzing the source term of Tritium in HTR-PM primary and secondary circuit, it is important and necessary to know the diffusion behavior of Tritium in SiC and Incoloy800H and furthermore, the detail mechanism of diffusion is also essential, which could not be obtained from traditional phenomenological analysis and conservative estimation. In order to solve this challenge, a framework with ab-initio methods is established. In this paper, the detail theory of ab-initio theory and the actual usage in the calculation of the diffusion path, barrier energy are given firstly. And then, the most physical path and the minimum energy barrier will be determined, which can be considered as the diffusion activation energy. The calculated results of activation energy of Tritium in SiC and Incoloy800H are 0.442eV and 0.757eV respectively. Furthermore, the theoretical results are compared with the experimental data, and it is found that both are in agreement with each other. These results are very helpful for understanding the diffusion behaviors of Tritium in HTR-PM materials and can be used to guide the tritium source term analysis in HTR-PM, which are first studied from a micro perspective.

scholarly journals Chemical Forms of Important Fission Products in Primary Circuit of HTR-PM under Conditions of Normal Operation and Overpressure and Water Ingress Accidents: A Study with a Chemical Thermodynamics Approach

2019 ◽  
Vol 2019 ◽  
pp. 1-12
Author(s):  
Chuan Li ◽  
Wenqian Li ◽  
Lifeng Sun ◽  
Haoyu Xing ◽  
Chao Fang
Keyword(s):  
High Temperature ◽  
Fission Products ◽  
Point Of View ◽  
Normal Operation ◽  
Primary Circuit ◽  
Chemical Thermodynamics ◽  
Chemical Forms ◽  
Operational Conditions ◽  
Water Ingress ◽  
High Temperature Gas

The chemical forms of important fission products (FPs) in the primary circuit are essential to the source term analysis of high-temperature gas-cooled reactors because the volatility, transfer, and diffusion of these radionuclides are significantly influenced by their chemical forms. Through chemical reactions with gaseous impurities in the primary circuit, these FPs exist in diverse chemical forms, which vary under different operational conditions. In this paper, the chemical forms of cesium (Cs), strontium (Sr), silver (Ag), iodine (I), and tritium in the primary circuit of the Chinese pebble-bed modular high-temperature gas-cooled reactor (HTR-PM) under normal conditions and accident conditions (overpressure and water ingress accident) are studied with chemical thermodynamics. The results under normal conditions show that Cs exists mainly in the form of Cs2CO3 at 250°C and gaseous form at 750°C, and for I and Ag, Ag3I3 and Ag convert to gaseous CsI and AgO, respectively, with increasing temperature, while SrCO3 is the only main kind of compound for Sr. It is also observed that new compounds are generated under accidents: I exists in HI form when a water ingress accident occurs. Regarding tritium, the chemical forms of FPs change little, but compounds need higher temperature to convert. Furthermore, hazard of some FPs in different chemical forms is also discussed comprehensively in this paper. This study is significant for understanding the chemical reaction mechanisms of FPs in an HTR-PM, and furthermore it may provide a new point of view to analyze the interaction between FPs and structural materials in reactor as well as their hazards.

Water-Ingress Accident of the 250MW Pebble-Bed Modular High Temperature Gas-Cooled Reactor

2009 ◽  
Author(s):  
Zheng Yanhua ◽  
Shi Lei
Keyword(s):  
High Temperature ◽  
Safety Valve ◽  
Primary Circuit ◽  
Fuel Temperature ◽  
Pebble Bed ◽  
Water Ingress ◽  
Design Basis ◽  
Design Basis Accident ◽  
Water Gas ◽  
High Temperature Gas

Water-ingress accident, caused by the steam generator heating tube rupture of a high temperature gas-cooled reactor, will introduce a positive reactivity to lead the nuclear power increase rapidly, as well as the chemical reaction of graphite fuel elements and reflector structure material with steam. Increase of the primary circuit pressure may result in the opening of the safety valve, which will cause the release of radioactive isotopes and flammable water gas. The analysis of such an important and particular accident is significant for verifying the inherent safety characteristics of the pebble-bed modular high temperature gas-cooled reactor. Based on the preliminary design of the 250MW Pebble-bed Modular High Temperature Gas-cooled Reactor (HTR-PM), the design basis accident of double-ended guillotine break of a heating tube has been analyzed by using TINTE, which is a special transient analysis program for high temperature gas-cooled reactors. Some safety relevant concerns, such as the fuel temperature and primary loop pressure, the graphite corrosion inventory, the water gas releasing amount, as well as the natural convection influence under the condition of the failure of the blower flaps shut down, have been studied in detail. The calculation result of the design basis accident indicates that, the maximal possible water ingress amount is less than 600 kg and the maximal fuel temperature keeps far below the design limitation of 1620°C. The result also shows that the slight amount of graphite corrosion will not damage the reactor structure and the fuel element, and there is no potential explosive risk caused by the opening of the safety valve.

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