Heavy Water Moderator Research Articles

A Comparison of Process Characteristics for the Recovery of Tritium from Heavy Water and Light Water Systems

A number of facilities have been either constructed or are operating to extract tritium from the heavy water moderator systems of nuclear reactors. However it is expected that most fusion reactor c...

Application of dicesium metaborate ion for the determination of boron by thermal ionisation mass spectrometry

Application of dicesium metaborate ion /Cs2BO 2 + / in Thermal Ionisation Mass Spectrometry /TIMS/ for the determination of boron present at sub ppm level in heavy water moderator as well as for the isotopic composition of boron in boron carbide is reported. Contamination of samples with natural boron while determining trace levels of boron in heavy water was checked by analysing SRM-952 isotopic reference material. The atom ratios of boron in B4C were determined by directly fusing the material on the tantalum filament with Cs2CO3 as well as with Na2CO3 and also by following the conventional fusion procedures and the results were compared.

Tritium Instrumentation for the Chalk River Nuclear Laboratories Tritium Extraction Plant

A Tritium Extraction Plant (TEP) is under construction at the Chalk River Nuclear Laboratories (CRNL) for the extraction of tritium from the heavy water moderator and coolant of research and power reactors owned by Atomic Energy of Canada Limited. Since the process equipment will contain a large inventory of tritium (about 20 g), plant operating personnel must be continually aware of process stream activity levels for economic reasons and promptly alerted in the event of leakage for personnel health protection purposes and inventory loss minimization. Consequently, the TEP is equipped with a number of tritium monitors for the continuous measurement of tritium contained in the process equipment, the building air and the plant exhaust stacks. This paper outlines the approach taken to provide tritium monitoring at the TEP for health protection, environmental and process requirements and describes the general features of specific monitors in each classification.

Moderator Detritiation at the Savannah River Plant

A study has been made of the technical and economic aspects of reducing tritium concentration in Savannah River Plant heavy-water moderator by 90%. A single detritiation plant would serve four operating reactors and the desired tritium reduction would be achieved in less than ten years. The process choice has narrowed to three processes. These involve a front-end extraction or preparation of molecular DT in a D2 stream, and a back-end fractional distillation of this stream followed by catalytic conversion to make 98% tritium T2.

Tritium instrumentation for the Chalk River Nuclear Laboratories tritium extraction plant

A Tritium Extraction Plant (TEP) is under construction at the Chalk River Nuclear Laboratories (CRNL) for the extraction of tritium from the heavy water moderator and coolant of research and power reactors owned by Atomic Energy of Canada Limited. Since the process equipment will contain a large inventory of tritium (about 20 g), plant operating personnel must be continually aware of process stream activity levels for economic reasons and promptly alerted in the event of leakage for personnel health protection purposes and inventory loss minimization. Consequently, the TEP is equipped with a number of tritium monitors for the continuous measurement of tritium contained in the process equipment, the building air and the plant exhaust stacks. This paper outlines the approach taken to provide tritium monitoring at the TEP for health protection, environmental and process requirements and describes the general features of specific monitors in each classification.

Moderator detritiation at the savannah river plant

A study has been made of the technical and economic aspects of reducing tritium concentration in Savannah River Plant heavy-water moderator by 90%. A single detritiation plant would serve four operating reactors and the desired tritium reduction would be achieved in less than ten years. The process choice has narrowed to three processes. These involve a front-end extraction or preparation of molecular DT in a D/sub 2/ stream, and a back-end fractional distillation of this stream followed by catalytic conversion to make 98% tritium T/sub 2/.

Enhanced tritium production for fusion reactors via3He(n, p)3 H in the heavy water moderator of a CANDU reactor

There is an increasing requirement for tritium to supply the fuel needs of current experimental fusion devices and in the initial startup of future power generating reactors. Tritium is produced in heavy water reactors through deuterium activation, but the total production capacity of Canadian operated CANDUs will fall short of future demands, during the period before and for some time after self-sufficient reactors become available. Consequently, methods of enhancing tritium generating rates warrant investigation. Herein we provide the results of an inquiry into the feasibility of enhancing tritium production levels through the activation of helium-3 following its external addition to the heavy water moderator system of a hypothetical 500–600 MWe CANDU reactor. The approach adopted involves simulation of the temporal evolution of the tritium activities, originating from2H(n,γ)3H and3He(n, p)3H, as described by a simple first order kinetic model. The results suggest that the frequent addition of helium-3 to the moderator water will enhance tritium production inventories. The enhancement factor is highly dependent upon the rate at which helium-3 irretrievably escapes to the moderator cover gas. However, the direct activation of helium-3, contained in a closed loop such as the annulus gas system, for example, would be essentially complete within a few weeks without any significant loss.

新型転換炉「ふげん」用炉内中性子検出器の開発

In the Prototype Heavy Water Reactor "Fugen", Zircaloy-2 is used as in-core structural material for neutron economy. In-core neutron detectors for the Local Power Monitor are placed in heavy water moderator of 50°C. Such "Fugen" in-core conditions bring a high level thermal neutron flux environment, which burns away the neutron conversion material (235U) in the detector more rapidly compared to that of the light water reactors. Therefore, it was strongly required to realize a neutron detector which could work for a long time under such environment.To resolve this unexperienced subject, the authors started to develop an advanced in-core neutron detector for "Fugen" by adopting various technologies, The developed neutron detectors have smart structures and excellent characteristics such as (1) light weight structure to avoid gas displacement due to γ-heating, (2) structure of assembling detectors in a Zircaloy-2 tube, (3) wide range and linear current measuring performance and (4) long life performance by the use of mixed uranium (235U+234U). This kind of in-core neutron detector is now in the reactor core of "Fugen" nuclear power plant and is contributing to the high-efficient reactor operation.

A comparison of PLW and PHW second-generation 232Th 233U reactors

The use of irradiated Th rods in 232Th 233U second-generation reactors was studied theoretically. It was found that the use of the heavy-water moderator in such reactors has considerable advantages over the use of the light-water one.

Comparison of methods for determination of boron in heavy water moderator

Five analysis methods were compared for the determination of boron in heavy water moderator: isotope dilution mass spectrometry, spectrophotometry, neutron activation, inductively coupled plasma – atomic emission spectrometry, and ion selective electrode potentiometry. Ten samples were analysed by each method; the results showed close agreement between all of the methods. Only mass spectrometry achieved the required precision (<1% rsd) for samples taken during initial reactor operation, but all of the methods achieved sufficient precision (<10% rsd) for samples taken during normal operation. For samples for which the 10B concentration must be determined, only mass spectrometry and neutron activation are applicable.

Canadian Experience with Tritium—The Basis of a New Fusion Project

Fusion power stations using the deuterium-tritium reaction will have substantial inventories of tritium in the oxide, molecular, and solid (metal hydride) forms. A new Canadian fusion engineering project based on Canada deuterium uranium (CANDU) operating experience with deuterium and tritium and plans to extract and concentrate tritium from Ontario Hydro's reactors is described. The aims of this project are to contribute to the international fusion effort by extracting useful existing information and translating that experience for application to fusion, and acting as a technology development agency by funding further research and development (R&D) in project mandate areas.Project R&D activities in each of the following five mandate areas are described:1. Fuel Systems and Tritium Management Programs2. Materials Technology Programs3. Equipment Development Programs (including remote operations)4. Health and Environmental Program5. Breeding Blanket Technology Program.Also summarized are health and safety experiences with tritium in the CANDU program and plans for large-scale tritium removal from heavy water moderator and coolant systems.

Effect of (γ,n) Reactions of Heavy Water Moderator on Beam Quality in Biomedical Irradiation Facility

The effect of (γ, n) reactions of heavy water on beam quality of a biomedical irradiation facility was studied. In an irradiation facility using thermal neutrons from a nuclear reactor, heavy water is widely employed as neutron moderator because of its good nuclear characteristics. It is well known that the threshold energy of (γ, n) reactions of heavy water is 2.2 MeV and fast neutrons are generated from the reactions. In 1982, we proposed a technique for the evaluation of (γ,n) reactions using a computer code ANISN-JR. In the present work, with further improved ANISN-JR for the proper estimation of the leakage, the comparison calculations both with and without (γ, n) reactions were carried out and their results were compared with those of the foil activation experiments at the KUR Heavy Water Facility. In the ignorance of (γ, n) reactions, fast and epithermal neutron fluxes are extremely underestimated for deeper penetration than 80 cm, while the calculated results including (γ, n) reactions give good agreements with experiments.

Effect of (.GAMMA.,n) reactions of heavy water moderator on beam quality in biomedical irradiation facility.

The effect of (γ, n) reactions of heavy water on beam quality of a biomedical irradiation facility was studied. In an irradiation facility using thermal neutrons from a nuclear reactor, heavy water is widely employed as neutron moderator because of its good nuclear characteristics. It is well known that the threshold energy of (γ, n) reactions of heavy water is 2.2 MeV and fast neutrons are generated from the reactions. In 1982, we proposed a technique for the evaluation of (γ,n) reactions using a computer code ANISN-JR. In the present work, with further improved ANISN-JR for the proper estimation of the leakage, the comparison calculations both with and without (γ, n) reactions were carried out and their results were compared with those of the foil activation experiments at the KUR Heavy Water Facility. In the ignorance of (γ, n) reactions, fast and epithermal neutron fluxes are extremely underestimated for deeper penetration than 80 cm, while the calculated results including (γ, n) reactions give good agreements with experiments.

Pressure Tubes: The Pressure Vessels in the CANDU Nuclear Power Reactor

One of the main engineering characteristics of the CANDU nuclear power reactor is the use of pressure tubes rather than one large pressure vessel to contain the fuel and coolant. The power reactor basically consists of a calandria, which is a vessel containing the low pressure heavy water moderator, end shields, and an array of identical pressure tube assemblies which project through the end shields and calandria. This paper briefly describes the CANDU reactor, some of the design and development done in support of the pressure tube concept, and the Canadian experience with pressure tubes.

Pressure Tubes: The Pressure Vessels in the CANDU Nuclear Power Reactor

One of the main engineering characteristics of the CANDU nuclear-power reactor is the use of pressure tubes rather than one large pressure vessel to contain the fuel and coolant. The power reactor basically consists of a calandria, which is a vessel containing the low pressure heavy water moderator, end shields, and an array of identical pressure tube assemblies which project through the end shields and calandria. This paper briefly describes the CANDU reactor, some of the design and development, done in support of the pressure tube concept, and the Canadian experience with pressure tubes.

The Canadian nuclear power program

Nuclear-electric generating stations, predominantly the 2000 MWe Pickering station near Toronto, currently produce 5 per cent of Canada's electric energy. By the year 2000 nuclear plants will probably supply more than 40 per cent of the country's electricity. The CANDU system, featuring pressure tube reactors, heavy water moderator and natural uranium fuel, is the preferred type and will remain so for many years to come. Envisaged is the evolutionary development of the CANDU fuel cycle to embrace the use of thorium and thereby extend nuclear fuel resources by a matter of centuries. The history of the Canadian nuclear power program, its present status and future outlook are reviewed, as are the safety and environmental aspects of nuclear power.

Investigation of the Fluorine-17 Activity as a Nuclear Power Monitor in the Heavy Water Moderated Reactor DIORIT

In the D2O moderator of a reactor, a significant 17F activity is produced by the reaction 16O(d, n)17F with recoiling deuterons. Investigations in the DIORIT reactor have shown that this activity can be used within certain limits to monitor the nuclear power.

Small reactors for desalination — A natural uranium heavy water moderated and cooled type feasibility study

Efforts towards the utilization of nuclear power in desalination to satisfy Egypt's long term water needs considered natural uranium heavy water moderated and cooled reactors as one of the promising prototypes. A feasibility study for a 40 MWth pilot plant was conducted and the main core features were determined. The concept comprised natural uranium metallic fuel, heavy water moderator and coolant in separate circuits, and aluminium alloy cladding and structural material. The design included a parametric investigation to determine optimum configurations. Results were shown giving cell and core details.

The application of space-dependent multigroup theory to the analysis of neutron slowing down time experiments I. Light and heavy water moderators

A detailed study is made of some recent measurements by Möller and Chen and Lidofsky of the most probable slowing down times of neutrons in light and heavy water. Using both an energy multigroup and a mixed-energy group-energy point technique, together with a moments-matching technique, the P1 and the diffusion approximations to the time-dependent Boltzmann equation are solved numerically. Good agreement is obtained with the spatially-dependent results at 1·46 eV obtained by Möller in light and heavy water. It is demonstrated that in order to reproduce the measurements of Chen and Lidofsky, made with a cadmium-shielded 1/v detector, it is necessary to allow for the energy dependence of the detector response. Generally, it is found that the P1 approximation reproduces these measurements better than the diffusion approximation.

Roots and Coefficients from the Integral Solution of the Reactor Kinetic Equations Applicable to Uranium-235 Fueled, Heavy Water Moderated Reactors

The characteristic parameters necessary to describe the kinetic behavior of D2O moderated reactors have been calculated for various prompt-neutron lifetimes. Comparison is made of the reactor respo...