Nuclear reactors heat pipe

There is a close kinship between the chemical process industry and the nuclear electric power industry. In tact once the physics of nuclear reaction was established the rest is chemistiy and hc.it ii an.sfer. The word "reactor" is from chemistry for the location the reaction takes place.. nuclear reactor consists of a vessel in which a nuclear reaction heats water to make steam to drive a turbine o generate electricity. Thus the primary components are pipes, valves, pumps heat exchangers, and water purifiers similar to the components found in a chemical plant. Following the success of WASH-1400, PSA was used to analyze the chemical proce.ssmg of nuclear fuel and. aste preparation for disposal. 

For example, one of the earliest types of nuclear reactors is the boiling water reactor (BWR) in which the reactor core is surrounded by ordinary water. As the reactor operates, the water is heated, begins to boil, and changes to steam. The steam produced is piped out of the reactor vessel and delivered (usually) to a turbine and generator, where electrical power is produced. 

A common thread in many of the reactor technologies that currently exist or that are under development is the use of water as the heat transport medium (the coolant ). In many respects, water is an ideal coolant, because it has a high heat capacity, can be obtained in a high purity, is inexpensive, has a wide liquid range (0-374.15 °C), is easily handled, and had been used since the dawn of steam power. Thus, in their most fundamental form, water-cooled nuclear reactors (WC-NRs) comprise a nuclear boiler, a heat transport system (piping, channels, steam generators, etc.), a set of turbines (high pressure, intermediate pressure, and low... 

Reactor Coolant Boundary. The reactor coolant boundary means all those coolant-containing components of nuclear reactors, such as pressure vessels, piping, pumps, valves, and heat exchangers, which are part of the reactor coolant system, or connected to the reactor coolant system, up to... 

On Etecember 8, 1995, a leakage of sodium occurred in the piping room (C) of the Secondary Heat Transport System (SHTS) while the output of the reactor was being raised for a plant trip test at 40% output as part of a series of performance tests. The nuclear reactor was shut down manually after the accident, and sodium was drained from the SHTS in which the accident occurred and also from the Loop C of the Primary Heat Transfer System (PHTS). The plant is currently in a low-temperature shutdown state. The plant conditions of Monju at the time of the sodium leak occurrence are shown in Fig. 3.1. 

Liquid metals are sometimes used as a heat-transfer fluid in cases where a fluid is needed over a wide temperature range at relatively low pressures. Liquid metals are often used in nuclear reactors and have high heat-transfer coefficients as well as a high heat capacity per unit volume. The high heat-transfer coefficients are due to the very high thermal conductivities and, hence, low Prandtl numbers. In liquid metals in pipes, the heat transfer by conduction is very important in the entire turbulent core because of the high thermal conductivity and is often more important than the convection effects. 

One of the first references to heat pipes in chanical reactors (they had been used in nuclear reactors), was in a methanation plant (Biery, 1977). Heat pipes were inserted next to rows of cylindrical ceramic catalyst columns, so that they took heat from hot spots on the catalyst. The vertical heat pipes then transferred the heat to a steam generator, located in the top of the reactor vessel. The steam was recovered for process use. 

Similar schemes are being considered for transport of energy from concentrated solar energy plants [44] [155]. It is possible to achieve solar fluxes at 1000 kWW at 1000"C, which is far above the fluxes in conventional tubular reformers of 100 kW/m (refer to Sections 1.2.2 and 3.2.2). One solution has been to separate the reforming reaction from the solar receiver by having a separate loop of a heat transfer media (as helium for the nuclear reactor). This was studied at first in a sodium heat pipe reformer [363]. However, reactors for direct absorption of the solar... 

Nuclear heat from the reactor core is removed passively by a lead-bismuth eutectic alloy coolant [XXIX-4], which flows due to natural circulation between the bottom and top plenums, upward through the fuel tubes and returning through the downcomer tubes. On top of the upper plenum, the reactor has multi-layer heat utilization vessels to provide an interface to systems for high temperature heat applications. A set of sodium heat pipes is in the upper plenum of the reactor to passively transfer heat from the upper plenum to the heat utilization vessels with a minimum drop of temperature. Another set of heat pipes transfers heat from the upper plenum to the atmospheric air in the case of a postulated accident. To shut down the reactor, a set of seven shut-off rods has been provided, which fall by gravity in the central seven coolant channels. Appropriate instmmentation like neutron detectors, fission/ ion chambers, various sensors and auxiliary systems such as a cover gas system, purification systems, active interventions etc. are being incorporated in the design as necessary. 

Nickel chromium iron alloys are very resistant to high purity water in a wide temperature range. Since these alloys are well suited for the plating of steel, alloys such as Alloy 600 (Mat.-No. 2.4816) and Alloy 800 (Mat.-No. 1.4876) are resistant to moderate oxygen and chloride quantities, and are used in nuclear reactors. Alloy 600 is used as a lining for steel tanks [174] as well as for tubing and pipes in heat exchangers [72,175]. The bahaviour of nickel and a few of its alloys is summarised in Table 13. 

Sodium A coolant in nuclear reactors Conducts heat well. Melts at only 98 C so the hot metal will flow along pipes. 

Wang, C., Guo, Z., Zhang, D., Qiu, S., Tian, W., 2013a. Transient behavior of the sodium-potassium alloy heat pipe in passive residual heat removal system of molten salt reactor. Progress in Nuclear Energy 68, 142—152. 

All mathematical models and computer codes that are used for safety-grade steady-state and transient analyses of nuclear reactor systems are sufficiently general that almost none of these assumptions are necessary. Two-phase fluid states are the norm for these models and codes. Although many include axial heat conduction in piping materials, two- and three-dimensional modeling within the working fluids is a specialized apphcation and has recendy begun to receive attention. 

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