Experimental Investigation of 14C in the Primary Coolant of the 10 MW High Temperature Gas-Cooled Reactor

Radiocarbon ◽  
2019 ◽  
Vol 61 (03) ◽  
pp. 867-884 ◽  
Author(s):  
F Xie ◽  
W Peng ◽  
J Cao ◽  
X Feng ◽  
L Wei ◽  
...  
Keyword(s):  
High Temperature ◽  
Sampling System ◽  
Primary Coolant ◽  
Carbon 14 ◽  
The Core ◽  
Purification System ◽  
Very High Temperature Reactor ◽  
Test Reactor ◽  
Production Mechanisms ◽  
High Temperature Gas

ABSTRACTThe very high temperature reactor (VHTR) is a development of the high-temperature gas-cooled reactors (HTGRs) and one of the six proposed Generation IV reactor concept candidates. The 10 MW high temperature gas-cooled reactor (HTR-10) is the first pebble-bed gas-cooled test reactor in China. A sampling system for the measurement of carbon-14 (14C) was established in the helium purification system of the HTR-10 primary loop, which could sample 14C from the coolant at three locations. The results showed that activity concentration of 14C in the HTR-10 primary coolant was 1.2(1) × 102 Bq/m3 (STP). The production mechanisms, distribution characteristics, reduction routes, and release types of 14C in HTR-10 were analyzed and discussed. A theoretical model was built to calculate the amount of 14C in the core of HTR-10 and its concentration in the primary coolant. The activation reaction of 13C has been identified to be the dominant 14C source in the core, whereas in the primary coolant, it is the activation of 14N. These results can supplement important information for the source term analysis of 14C in HTR-10 and promote the study of 14C in HTGRs.

Study on the Break Accidents of the HTR-PM Primary Loop

2016 ◽  
Author(s):  
Minggang Lang ◽  
Ximing Sun ◽  
Yanhua Zheng
Keyword(s):  
High Temperature ◽  
Pressure Vessel ◽  
Relief Valve ◽  
Primary Coolant ◽  
Primary Loop ◽  
The Core ◽  
Reactor Building ◽  
Temperature And Pressure ◽  
Coolant System ◽  
High Temperature Gas

In thermal hydraulics designing and safety analysis of the High Temperature gas-cooled Reactor-Pebble Bed (HTR-PM), the THERMIX code was used to study the behavior of helium in the primary coolant system. Once the helium leaks out of the primary loop through a break on the pressure boundary or an inadvertent open relief valve, it is difficult to simulate the conditions of the room where the release occurred with THERMIX. In this paper, the latest version of RELAP5/MOD4 was used to simulate the behavior of the helium released to the containment rooms. A RELAP5/MOD4 input deck of the HTR-PM, consisting of the core, the primary coolant system, the secondary loop and the containment, was developed and evaluated in this paper. Based on the model, this paper simulated the accidents consequences of large breaks or small breaks near the inlet or the outlet of the helium circulator located inside the steam generator pressure vessel. The calculating results illustrate that the temperature of the helium flowing into the reactor building through the break was no more than 280°C even after an un-isolating large break. The analysis shows that the systems function to scram the reactor and to monitor the core temperature and pressure after accidents would not be affected by breaks.

Design of the Gas Sampling and Analyzing System of HTR-PM

2017 ◽  
Author(s):  
Jiang Zhu ◽  
Feng Xie
Keyword(s):  
High Temperature ◽  
Reactor Core ◽  
Fission Products ◽  
Structural Materials ◽  
Primary Coolant ◽  
Primary Loop ◽  
Gas Sampling ◽  
Purification System ◽  
Safety Features ◽  
High Temperature Gas

The high temperature gas-cooled reactor pebbled-bed module (HTR-PM) which is a modular high temperature gas-cooled reactor demonstration power plant, is characterized by inherent safety features and high generating efficiency. It adopts numerous graphite for structural materials in the reactor core, helium as primary coolant, and tristructural isotropic (TRISO) coated particles embedded in the graphite matrix as fuel elements. However, at high temperature the impurities in the helium can react with the graphite to cause corrosion of structural materials. Therefore, it is very necessary to monitor and control the composition and content of gaseous impurities in the primary coolant. In HTR-PM, the gas sampling and analyzing system has been designed to sample the primary helium at different positions in the helium purification system which is used to reduce the quantity of chemical impurities and remove the radioactive dust and gaseous fission products in the primary loop, and monitor the gas composition and individual concentration online. In the current paper, the composition of the gaseous impurities which need to be monitored in the primary loop of HTR-PM is presented, the design of the gas sampling positions in the helium purification system is discussed, and the main gas analyzing instruments are introduced.

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.

scholarly journals The Design of Turbomachinery for the Gas Turbine (Direct Cycle) High Temperature Gas Cooled Reactor Power Plant

1977 ◽  
Author(s):  
R. G. Adams ◽  
F. H. Boenig
Keyword(s):  
High Temperature ◽  
Power Plant ◽  
Gas Turbine ◽  
Power Conversion ◽  
Reactor Power ◽  
Working Fluid ◽  
Primary Coolant ◽  
Reactor Power Plant ◽  
Direct Cycle ◽  
High Temperature Gas

The Gas Turbine HTGR, or “Direct Cycle” High-Temperature Gas-Cooled, Reactor power plant, uses a closed-cycle gas turbine directly in the primary coolant circuit of a helium-cooled high-temperature nuclear reactor. Previous papers have described configuration studies leading to the selection of reactor and power conversion loop layout, and the considerations affecting the design of the components of the power conversion loop. This paper discusses briefly the effects of the helium working fluid and the reactor cooling loop environment on the design requirements of the direct-cycle turbomachinery and describes the mechanical arrangement of a typical turbomachine for this application. The aerodynamic design is outlined, and the mechanical design is described in some detail, with particular emphasis on the bearings and seals for the turbomachine.

scholarly journals Conceptual Core Design Study of the Very High Temperature Gas-Cooled Reactor (VHTR) Upgrading the Core Performance by Using Multihole-Type Fuel

2008 ◽  
Vol 7 (1) ◽  
pp. 32-43 ◽  
Author(s):  
Kazutaka OHASHI ◽  
Tetsuo NISHIHARA ◽  
Kazuhiko KUNITOMI ◽  
Masaaki NAKANO ◽  
Yujiro TAZAWA ◽  
...  
Keyword(s):  
High Temperature ◽  
Design Study ◽  
The Core ◽  
Conceptual Core ◽  
Very High ◽  
Type Fuel ◽  
High Temperature Gas

An Experimental Study on Insulating Property of Helium in High Temperature Gas Cooled Reactor

2014 ◽  
Author(s):  
Shan Yue ◽  
Xingnan Liu ◽  
Zhengang Shi
Keyword(s):  
High Temperature ◽  
Electrical Equipment ◽  
Structure Design ◽  
Nuclear Industry ◽  
Parallel Plane ◽  
Primary Coolant ◽  
Experimental Platform ◽  
Insulating Properties ◽  
High Temperature Gas ◽  
Better Than

HTGR, short for high temperature gas cooled reactor, has gained a lot of attention in nuclear industry. Gas helium, 7MPa in pressure, is used as primary coolant of HTR-PM in where there are a lot of electrical equipment. Insulating property of helium is worse than that of air according to Paschen curves and there are very few articles or related standards about insulating property of high pressure gas helium, which makes the electrical equipment structure design lack of basis. In this study, an experimental platform for testing insulating performance is designed, based on which the experiments of testing the withstanding voltages of penetration assemblies and the breakdown voltages of parallel plane electrodes at different pressures are carried out. The results show that for both the penetration assemblies and the parallel plane, their breakdown voltages in helium are far lower than in air under the same condition of 15°C /0.1MPa. For the penetration assemblies, their insulating properties in helium at 150°C/7MPa are better than those in air at 15°C/0.1MPa.

The Production and Release of 14C in HTGR

2014 ◽  
Vol 1030-1032 ◽  
pp. 232-235
Author(s):  
Fu Juan Han ◽  
Jun Feng Li
Keyword(s):  
High Temperature ◽  
Nuclear Reactor ◽  
Cosmic Ray ◽  
Environment Impact ◽  
Carbon 14 ◽  
Forms Of Carbon ◽  
Release Form ◽  
High Temperature Gas

Carbon-14 is a radionuclide, which is a by-product in the operation of various nuclear reactor facilities. it also came from the interaction of cosmic ray with nitrogen and hydrogen in the atmosphere globally. This article elaborates the source of the 14C in High-Temperature Gas-Cooled Reactor, the amount of 14C released to the environment, as well as the forms of carbon-14. Meanwhile, the author presents the environment impact of this radionuclide. This paper concluded that 14N (n, p) 14C reaction in the fuel spheres and coolant gas is major source, and CO2 is major release form. The conclusion could provide the references and suggestions for storage, disposal and release reduction of this type of waste.

Investigation on Iodine Release Behavior During the Operation of High Temperature Engineering Test Reactor (HTTR)

2013 ◽  
Author(s):  
Shohei Ueta ◽  
Hiroyuki Inoi ◽  
Yoshitaka Mizutani ◽  
Hirofumi Ohashi ◽  
Jin Iwatsuki ◽  
...  
Keyword(s):  
High Temperature ◽  
Local Area ◽  
Release Behavior ◽  
Primary Coolant ◽  
Energy Agency ◽  
Xenon Isotopes ◽  
Test Reactor ◽  
Forced Cooling ◽  
Iodine Release ◽  
Testing Plan

Japan Atomic Energy Agency (JAEA) has planned to investigate on iodine release behavior from fuel through the testing operation of High Temperature Engineering Test Reactor (HTTR) in order to contribute to the reasonable estimation of the radiation exposure necessary for the realization of HTGR in the future. In this test, the fractional release of iodine will be measured and evaluated by measuring xenon isotopes, the daughter nuclides of iodine isotopes, in the primary coolant sampling under the loss-of-forced cooling (LOFC) test by which the primary coolant circulator is shut down and/or the manual scram test of HTTR. In parallel, the local area of primary coolant circuit where iodine is plated-out will be evaluated. This paper describes the testing plan and the preliminary analytical study on the release behavior of iodine and xenon isotopes through the operation of HTTR.

scholarly journals Study on Air Ingress Mitigation Methods in the Very High Temperature Gas Cooled Reactor (VHTR)

2011 ◽  
Author(s):  
Chang H. Oh ◽  
Eung S. Kim
Keyword(s):  
High Temperature ◽  
Root Cause ◽  
The Core ◽  
Graphite Oxidation ◽  
Simulation Results ◽  
Oxidation Damage ◽  
Air Ingress ◽  
Mitigation Methods ◽  
Very High ◽  
High Temperature Gas

An air-ingress accident followed by a pipe break is considered as a critical event for a very high temperature gas-cooled reactor (VHTR) safety. Following helium depressurization, it is anticipated that unless countermeasures are taken, air will enter the core through the break leading to oxidation of the in-core graphite structure. Thus, without mitigation features, this accident might lead to severe exothermic chemical reactions of graphite and oxygen depending on the accident scenario and the design. Under extreme circumstances, a loss of core structural integrity may occur along with excessive release of radiological inventory. Idaho National Laboratory under the auspices of the U.S. Department of Energy is performing research and development (R&D) that focuses on key phenomena important during challenging scenarios that may occur in the VHTR. Phenomena Identification and Ranking Table (PIRT) studies to date have identified the air ingress event, following on the heels of a VHTR depressurization, as very important (Oh et al. 2006, Schultz et al. 2006). Consequently, the development of advanced air ingress-related models and verification and validation (V&V) requirements are part of the experimental validation plan. This paper discusses about various air-ingress mitigation concepts applicable for the VHTRs. The study begins with identifying important factors (or phenomena) associated with the air-ingress accident using a root-cause analysis. By preventing main causes of the important events identified in the root-cause diagram, the basic air-ingress mitigation ideas can be conceptually derived. The main concepts include (1) preventing structural degradation of graphite supporters; (2) preventing local stress concentration in the supporter; (3) preventing graphite oxidation; (4) preventing air ingress; (5) preventing density gradient driven flow; (6) preventing fluid density gradient; (7) preventing fluid temperature gradient; (7) preventing high temperature. Based on the basic concepts listed above, various air-ingress mitigation methods are proposed in this study. Among them, the following one mitigation idea was extensively investigated using computational fluid dynamic codes (CFD) in terms of helium injection in the lower plenum. The main idea of the helium injection method is to replace air in the core and the lower plenum upper part by buoyancy force. This method reduces graphite oxidation damage in the severe locations of the reactor inside. To validate this method, CFD simulations are addressed here. A simple 2-D CFD model was developed based on the GT-MHR 600MWt as a reference design. The simulation results showed that the helium replaces the air flow into the core and significantly reduces the air concentration in the core and bottom reflector potentially protecting oxidation damage. According to the simulation results, even small helium flow was sufficient to remove air in the core, mitigating the air-ingress successfully.

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