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Water-Cooled Reactors
Published in William J. Nuttall, Nuclear Renaissance, 2022
Another long-standing weakness of the traditional CANDU reactor is the flip side of a positive attribute discussed in the previous subsection. The ability to produce large significant amounts of tritium is both a blessing and a curse. Although the neutron adsorption cross section of deuterons (the hydrogen atom nuclei in heavy water) is much lower than the equivalent cross section in light water, it is not zero. When deuterium atoms capture a neutron, they become tritium atoms. The tritium is retained within heavy water molecules as a radioactive liquid. Tritium is a form of hydrogen. Thankfully the tritium is locked within water molecules and in that form is not easily absorbed in metals and other components. Vapour leaks, however, need to be monitored to ensure there is no inhalation or ingestion risk to workers. Generally around the world PHWR technology has a very good record of worker safety.
Desalination
Published in P.K. Tewari, Advanced Water Technologies, 2020
Nuclear energy has potential to deal with the carbon footprint, as it provides low- carbon desalination. It can take the form of heat/electricity producing fresh water from seawater. The pressurized heavy water reactor (PHWR)-based nuclear power plant uses natural uranium as fuel and heavy water as moderator. It operates at about 4 megapascal (MPa) steam pressure and 250°C steam temperature. As the enthalpies of steam available at the entrance to the high-pressure (HP) turbine of a pressurized heavy water reactor-based nuclear power plant (NPP) are lower than with a fossil fuel-based conventional power plant, the specific steam consumption in the nuclear power station is higher. This means more steam is available from nuclear power plants that could be gainfully utilized for thermal desalination (Table 5.4).
Nuclear Energy Security
Published in Maria G. Burns, Managing Energy Security, 2019
The PHWR uses natural uranium in its unenriched form as fuel. It is mainly used in Canada and India, and represents about 12% of reaction worldwide. Heavy water, i.e., a type of water that comprises deuterium, a hydrogen isotope, is used for its cooling and neutron-moderation operations. One of its benefits is the ability to continue operations and fuel replenishment operations without the need to be shut down.
Development of the Assembly-Level Monte Carlo Neutron Transport Code M3C for Reactor Physics Calculations
Published in Nuclear Science and Engineering, 2020
Anek Kumar, Umasankari Kannan, S. Ganesan
The pressurized heavy water reactor30 (PHWR) is a pressure tube–type reactor with heavy water as moderator and coolant, and natural uranium dioxide as fuel. The fuel bundle consists of a 19-rod cluster. Using the developed Monte Carlo code, k-infinity (kinf) is calculated for a 220-MW(electric) PHWR rod fuel cluster in the cold condition assuming that fuel, coolant, and moderator temperatures are all the at same temperature, 25°C. The specification of the 19-rod fuel cluster is presented in Table VII. The details of this cluster can be found in Ref. 30. The 19-rod fuel cluster is shown in Fig. 6. We have simulated the same cluster also by the deterministic neutron transport theory code CLUB (Refs. 31 and 32) using the 172-energy group WIMSD nuclear data library based on ENDF/B-VII.0 point data for the kinf with reflective boundary condition. The value of kinf for this cluster using CLUB is 1.14125 (Ref. 25). The same test problem is also simulated using the developed M3C code using a pointwise nuclear data set based on ENDF/B-VII.0. The value of kinf is found to be 1.13971 0.00086, which can be considered in good agreement with the previous value of kinf calculated from the deterministic code CLUB. The comparison with CLUB is done for curiosity and historical purposes as the WIMSD convention–based CLUB code has several physics approximations as compared to a Monte Carlo code starting with a basic evaluated nuclear data file. These approximations in WIMSD physics include multigroup treatment, treatment of (n,xn) cross sections as negative absorption, truncation of anisotropy in the treatment of cross sections, an upper energy limit of 10 keV for resonance self-shielding, and intermediate resonance approximation, etc. Therefore, the results by a multigroup approximation should not be used to validate a Monte Carlo code. The blind comparison is presented, in the Indian context, merely for historical purposes and these sample comparison results should not be generalized.