Cooling systems water-cooled reactors

The Hanford N Reactor. The Hanford N reactor was built in 1964 for purposes of plutonium production during the Cold War. It used graphite as moderator, pierced by over 1000 Zircaloy 2 tubes. These pressure tubes contained slightly enriched uranium fuel cooled by high temperature light water. The reactor also provided 800 MWe to the Washington PubHc Power Supply System. This reactor was shut down in 1992 because of age and concern for safety. The similarity to the Chemobyl-type reactors played a role in the decision. 

Borgartz, B. O., T. P O Brien, N. J. M. Rees, and A. V. Smith, 1969, Experimental Studies of Water Decompression through Simple Pipe Systems, CREST Specialist Meeting on Depressurization Effects in Water-Cooled Reactors, Bettelle Institute, Frankfurt, FRG. (3)... 

Mass Transport at Very Low Concentrations. Reactor Circuits. Early in the development of water-cooled reactors, it became apparent that at temperatures of 250-300 C with a non-isothermal circuit, corrosion of carbon steel could lead to significant mass transport of iron if the chemistry of the system were not properly controlled. The resulting buildup of large deposits of crud" on fuel surfaces caused fuel failure. However, the large cost differential between carbon steel and stainless steel provided an incentive to identify chemistry conditions for the successful use of carbon steel. 

Sakaba, N., et al. (2007), Conceptual Design of Hydrogen Production System with Thermochemical Water-splitting Iodine-Sulphur Process Utilizing Heat from the High-temperature Gas-cooled Reactor HTTR , International Journal of Hydrogen Energy, 32 (17), pp. 4160-4169. 

We have used the reactor cooling water valve to stabilize the system by controlling reactor temperature. However there is no specific temperature at which the reactor must operate. The best way to manage the reactor temperature setpoint is not immediately obvious. It might be used in conjunction with the production rate controller, i.e., higher temperatures may be needed to increase throughputs. It might be adjusted to maximize yields and suppress undesired by-products. 

The intense primary y radiation due to nuclear fission, the secondary y radiation emitted by the fission and activation products and the radiation from the fission products give rise to radiation-induced chemical reactions. The most important reaction is the radiation decomposition of water in water-cooled reactors, leading to the formation of H2, H2O2 and O2. Many substances dissolved in the water influence the formation of H2 (Fig. 11.18). In most closed coolant systems equipment for... 

In order to compensate the excess reactivity (section 11.1), in water-cooled reactors boric acid is added to the coolant in concentrations up to about 0.2%. The concentration is reduced with increasing burn-up. The pH is adjusted to by addition of 1 to 2 mg LiOH per litre water to lower the solubility of the metal oxides and hydroxides, respectively, produced by corrosion on the walls of the cooling system. 

Gas cooled reactors use carbon dioxide under pressure as a recirculating heat transfer medium (coolant) between the hot nuclear reactor core and water in a secondary circuit in order to raise steam and electrical power in an otherwise conventional high pressure steam generator/turbine/condenser loop. The role played by ion exchange is denoted by systems A-D in Figure 8.22. 

The primary coolant circuit of a water-cooled reactor (including BWRs and PWRs) has several loops, including the main coolant loop, a core heat removal system, and a reactor water cleanup system. However, it is convenient, for computational purposes, to differentiate between the main loop, which has a high flow fraction, and the secondary loops, for which the flow fractions are small. The species concentrations and electrochemical potential (ECP) are solved for in the main loop and the values at the entrance to the secondary loop are used as the initial conditions for solving the system of equations for the secondary loops of interest. Mass balance is applied at each point where more than one section comes together. 

Nuclear Energy Research Advisory Committee and Generation IV International Forum, Generation IV Roadmap - R D Scope Report for Water-Cooled Reactor Systems , GIF -003-00, (December 2002). 

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