Nuclear reactors heavy water reactor

Hydrogen is also important in fuel production. Hydrocracking uses the partial pressure of hydrogen gas to break down complex organic molecules, and forms by-products such as ethane, aromatics, and jet fuels. Liquid hydrogen is also used as a rocket fuel. In fission-based nuclear reactors, heavy water (where deuterium replaces regular hydrogen) is used as a neutron moderator. 

The main technological uses for UO2 are found in the nuclear fuel cycle as the principal component for light and heavy water reactor fuels. Uranium dioxide is also a starting material for the synthesis of UF [10049-14-6] 6 (both critical for the production of pure uranium metal and... 

The next presentations discussed chemical problems encountered in the nuclear power industry. S. R. Hatcher (Atomic Energy of Canada Ltd., Pinawa) gave a general review covering the chemistry of established and novel nuclear fuels, heavy-water production, and reactor operation. 

Radioactive waste treatment applications have been reported [3-9] for the laundry wastes from nuclear power plants and mixed laboratory wastes. Another interesting application of reverse osmosis process is in decontamination of boric acid wastes from pressurized heavy water reactors (PHWRs), which allows for the recovery of boric acid, by using the fact that the latter is relatively undissociated and hence wdl pass with water through the membrane while most of the radioactivity is retained [10]. Reverse osmosis was evaluated for treating fuel storage pool water, and for low-level liquid effluents from reprocessing plants. 

Heavy-water reactors utilize heavy water (D2O) as a moderator. They can be operated with natural uranium, since the capture cross-section for the thermal neutrons, necessary for controlling nuclear chain reactions, is very low for D2O compared with H2O. Enrichment of U is therefore not necessary. The high price of heavy water (only present as 0.015% in natural water) is, however, a disadvantage. The resulting higher investment costs... 

The main advantage of a heavy water reactor is that it eliminates the need for building expensive uranium enrichment facilities. However, D2O must be prepared by either fractional distillation or electrolysis of ordinary water, which can be very expensive considering the amount of water used in a nuclear reactor. In countries where hydroelectric power is abundant, the cost of producing D2O by electrolysis can be reasonably low. At present, Canada is the only nation successfully using heavy water nuclear reactors. The fact that no enriched uranium is required in a heavy water reactor allows a country to enjoy the benefits of nuclear power without undertaking work that is closely associated with weapons technology. 

In the CANDU heavy-water reactor the dominant source of tritium is the deuterium activation reaction of Eq. (8.53). The data given in Prob. 3.3 for the Douglas Point Nuclear Power Station provide a basis for estimating the rate of production of tritium in the heavy-water moderator and coolant ... 

In the current structure of nuclear power, light water reactors (LWRs) are predominant over a small number of heavy water reactors (HWRs), and even smaller number of fast breeder reactors (FBRs). However, an increase of FBR share can be predicted for the future, taking into account their unique properties. First of all, there is the capability of nuclear fuel breeding by involving into the fuel cycle. Secondly, there is the fast reactor s flexibility permitting its use as plutonium incinerators and minor actinides transmutation. Thus, unless new sources of energy are found, the development of nuclear power will be necessarily based on fast breeder reactors. 

This order applies to all varieties of reactors including, but not limited to light water moderated reactors, heavy water moderated reactors, liquid metal cooled reactors, gas cooled reactors and short-pulse transient reactors. Space reactor power and propulsion systems and critical facilities require special design criteria. Attachment 4 is reserved for Nuclear Safety Design for critical facilities and space reactors. 

With India s well-known program involving heavy water reactors and fast breeders, their early involvement with MSR development is surprising to some. The Bhabha Atomic Research Centre (BARC) was involved with official collaborations with ORNL from 1969 to 1975 on MSBR research. Facilities were built based on salt chemistry and, in particular, studies carried out on PuFj solubility remain of great value today (Venugopal, 2013). The 2013 Conference on Molten Salts in Nuclear Technology (CMSNT) held at BARC detailed India s renewed interest in a wide variety of MSR and FHR concepts (http //moltensaltindia. org/speakers-presentations/). 

The product, called uranium ore concentrate (and sometimes yellow cake), contains 65%-85% UjOg, is then shipped to the UCF where the uranium is dissolved and concentrated, and then pnrifled and converted either to the proper form needed for fnel elements (usnally nraninm oxide for graphite type or heavy water reactors) or to the feed material reqnired for isotope enrichment (usually uranium hexafluoride) (Figure 1.10). Following is either fabrication of fuel elements or enrichment to LEU for fneling light water reactors or to HEU for special reactors or nuclear weapons (special nnclear materials (SNM)). The product of the enrichment process, either LEU or HEU, mnst then be converted into the suitable form for the applicatiou— once again nsnally an oxide or metal. 

As a member of the CANDU family, the CANDU 300 design closely follows that of the larger CANDU 600 and CANDU 950 nuclear power plants and is is illustrated in Figure A key CANDU features include a pressure tube reactor, heavy water (D2O) moderator, natural uranium fuel, and on-power refuelling. 

CIRENE Is a pressure tube heavy water reactor cooled by boiling light water. A 40 MW(e) demonstration plant is under construction at the Latina site. The completion of the plant is scheduled for 1985. The realization of the Latina plant is carried out jointly by ENEA (the National Commission for Nuclear and Alternative Energy Sources) and ENEL (the National Electricity Generating Board) NIRA is the main contractor for the nuclear island. 

A notable exception is provided by national experience of India, a developing country that is successfully ongoing with operation and construction of new nuclear power plants with the domestically produced pressurized heavy water reactors of 209 and 490 MW(e) net capacity. 

Most studies of the time evolution of the fuel cycle and the evolving mix of reactor types during future decades have been based on global (or national) nuclear energy demand scenario analyses which, up to now, have assumed the use of traditional reactor types, such as LWRs, pressurized heavy water reactors (PHWRs), and fast breeder reactors (FBRs). Possible implications of small reactors without on-site refuelling on the transition timing and strategy have not yet been assessed extensively. 

Figure VIII-1 shows a simplified schematic diagram of the nuclear steam supply system with the Package-Reactor. The concept resembles a calandria-type pressurized heavy water reactor (e.g., the FUGEN advanced thermal reactor (ATR) or CANDU reactors) since all these employ pressure tubes. But the Package-Reactor is somewhat different from the ATR or the CANDU. The Package-Reactor employs natural circulation with two-phase flow for core cooling and has no recirculation pumps. The height of the pressure tubes of the cassettes is required to be as low as possible to attain a compact unit. Two-phase flow with high void fractions similar to BWRs is adopted to attain natural circulation with a cassette height of 6 m and a fuel rod length of 3.65 m.

AHWR = Advanced Heavy Water Reactor Dep. U = Depleted Uranium Fuel Reproc. = Fuel Reprocessing HWB = Heavy Water Board IRE = Indian Rare Earth NFC = Nuclear Fuels Complex SSSF = Solid Storage and Survellance Facility UCIL = Uranium Corporation of India Limited WIP = Waste Immobilization Plant. 

To build its research reactors, the Montreal lab needed a remote location that would enhance secrecy and isolate potential radioactive hazards from large centres of population. To this end it shifted its base of operations to Chalk River - a Canadian Pacific Railway division point on the south side of the Ottawa River about one hundred and thirty miles Northwest of Ottawa. Engineers and construction workers descended on the wilderness outpost and began constructing nuclear-research facilities. The first was the Zero Energy Experimental Pile (ZEEP), a small heavy-water reactor. Its start-up on September 5, 1945 - just a month after Hiroshima and Nagasaki - marked the first successful peaceful atomic reaction outside the United States. 

Under the CARA project [8] CNEA is developing an advanced fuel bundle concept for heavy water reactors, specially designed to fit the Argentinean fuel cycle requirements. The CARA fuel bundle can be used in the reactors of both types and will substantially improve the competitiveness of nuclear option in Argentina. 

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