RU2219603C2 - Thermionic conversion power reactor - Google Patents

Abstract

FIELD: nuclear power engineering and space engineering; space-based nuclear power plants. SUBSTANCE: thermionic conversion power reactor has power generating stacks in the form of pressurized vessel provided with coolant inlet and outlet pipes disposed at one of its ends; this vessel accommodates cooled thermionic powergenerating fuel assemblies, coolant dispensing and accumulating headers disposed at two ends of power-generating stacks; connected to accumulating header is coolant outlet pipe wherein at least one coolant feed pipe is installed inside each stack coaxially to power-generating fuel assemblies; one end of this pipe is hydraulically joined with coolant inlet pipe and other end is hydraulically connected to coolant dispensing header. All power- generating fuel assemblies operate under approximately same coolant temperature conditions. EFFECT: enhanced power generation efficiency, reduced space requirement, facilitated assembly, reduced heat transfer from one part of core to other. 1 cl, 3 dwg

Description

 The invention relates to nuclear energy and space technology and can be used to create predominantly space nuclear power plants.

 The thermionic reactor-converter (TRP) of a space nuclear power plant (NPP) can be based on thermal, intermediate, and fast neutrons. TRP on thermal (and intermediate) neutrons due to the presence in the core of the moderator can be created only up to electric powers of not more than 100 kW and a relatively low resource. Fast neutron propellants can be created at power from 100 kW to megawatts.

 Known TRP on thermal neutrons of the space nuclear power plant "Topaz" [1]. It contains an active zone (A3), consisting of a moderator and thermionic power generating assemblies (EGS), commonly called thermionic power generating channels (EGC), a reflector in which the controls are in the form of rotary drums. EHS from the outside are cooled by a heat carrier in the form of a eutectic NaK alloy. Such a TRP successfully worked out in space, generating an electric power of about 5 kW for about a year.

 Known TRP on fast neutrons according to the patent [2]. It contains AZ recruited from EHS and booster fuel elements. Such a TRP has a relatively small volume of AZ and, therefore, a small mass of radiation protection.

 However, the ground-based development of such a TRP requires a large amount of work, since the bulk of the tests to verify technical solutions and the development of reliability indicators should be performed during nuclear power tests of the TRP or even a nuclear power plant with TRP.

 Known TRP patent [3]. It contains an AZ composed of EGCs and booster fuel rods, which are compactly housed in an additional sealed enclosure equipped with an autonomous cooling system. Such a TRP has a relatively small volume of the core and, therefore, a small mass of radiation protection.

 However, the ground-based development of such a TRP requires a large amount of work, since the bulk of the tests to verify technical solutions and the development of reliability indicators should be performed during nuclear power tests of the TRP or even a nuclear power plant with TRP.

 Quite close to the invention in technical essence is a fast neutron TRP of a modular scheme for high-power space nuclear power plants described in [4]. TRP contains AZ, recruited from hydraulically independent power generating packages (EGP), consisting of a housing, inside which are placed thermionic EHS. Each EGP in the TRP has an independent cooling system in the form of an autonomous lithium circuit with coolant collectors located at the ends, having nozzles for entering and leaving the coolant. The controls in the form of rotary drums are located in the side reflector of the TRP.

 Such a TRP can also have a relatively low mass and is designed for electric power from 100-150 kW to several megawatts. The modular construction of TRP significantly simplifies experimental testing, since the bulk of the tests to verify technical solutions and develop reliability indicators can be performed with bench-based nuclear-free testing of EGP with electric heating.

 However, the introduction of modular construction, on the one hand, simplifies the assembly of the heat transfer unit, since it is assembled from a limited number of EGPs, and on the other hand, it complicates the assembly, since it requires the placement of a large number of pipelines with a coolant on both sides of the heat transfer unit. It also increases the dimensions of the TRP, and therefore, the mass of radiation protection from radiation from the reactor.

 Closest to the invention in technical essence is the TRP according to the patent [5]. It contains an active zone of at least two electro-generating packages (EGP) in the form of a sealed enclosure equipped with nozzles for entering and leaving the coolant, with thermoemissive EHS located inside the enclosure and two collectors of coolant located at the ends of the pack, and a partition is installed inside each EGP hydraulically dividing the EGS placed in the package into two groups and one of the coolant collectors in two parts, and the nozzles for entering and leaving the coolant are connected to each th of the parts separated by a partition manifold.

 Such a TRP can also have a relatively low mass and is designed for electric power from 100-150 kW to several megawatts. The modular construction of TRP significantly simplifies experimental testing, since the bulk of the tests to verify technical solutions and develop reliability indicators can be performed with bench-based nuclear-free testing of EGP with electric heating. Placing pipelines from one end of the TRP simplifies the assembly of the TRP, reduces the size and weight of radiation protection.

 However, the presence of a partition in each EGP leads to two undesirable consequences, namely, the presence of two groups of EHS working at different average temperatures of the coolant, and, consequently, the collector temperatures, and heat recovery in the core through the partition. The first leads to a decrease in the efficiency of TRP due to the fact that half of the EHSs do not work at the optimal collector temperature with a decrease in the electric power density while increasing the temperature of the EHS emitters. The second, due to heat transfer through a partition from half of the EGP with a “hotter” coolant to the other half with a “colder” coolant, reduces the heat removal efficiency, requires an increase in the coolant flow rate, and consequently, increased energy costs for pumping the coolant through the TRP core.

 The objective of the invention is to increase the efficiency of electricity generation in TRP while maintaining compactness and ease of assembly by providing the possibility of operation of all EHS in approximately the same conditions for the temperature of the coolant and reduce heat leakage from one part of the core of the TRP to another.

 The task is achieved in the TRP, containing at least two EGPs in the form of a sealed enclosure, equipped with nozzles for entering and exiting the coolant located at one of the ends, with thermoemissive EHS located inside the enclosure and distributing and collecting coolant collectors located at the two ends of the EGP, moreover, a nozzle for the outlet of the coolant is connected to the collection manifold, in which at least one tube for supplying heat is installed inside each EGP coaxially with the thermionic EHS a carrier, at one end hydraulically connected to a nozzle for entering the coolant, and the other end is hydraulically connected to a distributing collector of the coolant.

 Figure 1-3 shows structural diagrams explaining the essence of the proposed technical solution, namely: figure 1 shows the cross section of the TRP, and in figure 2 and figure 3 is a longitudinal and cross section of the EGP from which the active zone of the TRP is drawn .

 The TRP contains an EGP 1 and a side reflector 2, in which the TRP controls are located in the form of rotary cylinders 3 with neutron-absorbing plates 4. The EGP includes a sealed housing 5, inside of which are thermionic EHS 6, the outer casings of which are cooled by a heat carrier 7, for example, NaK eutectic alloy or Li. Inlet and outlet of the coolant is carried out, respectively, through the nozzles 8 and 9. The nozzle 8 for supplying the coolant is hydraulically connected to one end of the tube 10, mounted coaxially with the thermionic EHS 6. The second end of the tube 10 is hydraulically connected to the distributing collector 11 of the coolant. The length of the tube 10 is not less than the length of the active part of the EHS 6. The prefabricated collector 12 of the coolant is placed at the other end of the EHP and is hydraulically connected to the pipe 9 for removal of the coolant. The arrows in figure 2 shows the flow of coolant in the EGP. The EHS 6 are equipped with current outputs 13, which are switched in the switching chamber 14, for example, in series-parallel, to obtain the required voltage and current of the EHP. From the switching chamber 14 through the sealed leads are two current output 15.

 TRP works as follows.

 In the initial state, the rotary cylinders 3 are in the position of the absorbing plates 4 to the AZ with EGP 1. Therefore, the TRP is not critical and in this state it is launched into space as part of the nuclear power plant. In a radiation-safe orbit, for example, 800 km high, a nuclear power plant is launched. To do this, automatically, on command from the Earth or the control system of the nuclear power plant, the rotation of the rotary cylinders 3 is carried out in such a way that the plates 4 extend from A3. The reaction of fission of the fuel material in the cores of the EHS 6 of each of the EGP 1 begins.

The generated heat is removed from the outer surface of the EHS 6 casings by the coolant 7, for example, NaK or Li, supplied to each EHP 1. The coolant 7 is supplied to the EHP through the inlet 8, from which it enters the tube 10, passing through which it enters the distribution manifold 11 , in which it rotates through 180 ^o and enters into the gaps between the outer surfaces of the EHS 6. The flowing coolant 7, cooling the EHS 6, is heated and then enters the collection manifold 12, from which through the pipe 9 enters the cooling system of the nuclear power plant (not shown).

 After reaching the working level of thermal power, a working fluid (cesium vapor) is supplied to the EHS 6 and they begin to generate electricity. EHS 6 inside EHP 1 are switched in parallel, sequentially or parallel-sequentially. Switching is carried out in the switching chamber 14, from which, with the help of current leads 15 isolated from the housing, the electric energy is supplied to the consumer or to external switching devices (not shown). The heat of the thermodynamic cycle that is not converted to EHS 6 is removed by the heat carrier 7, as described above, and then is dumped into space by radiation in a refrigerator-emitter (not shown).

 Since the tube 10 is made of metal, there will be a recovery, that is, heat transfer from the coolant 7 flowing between the EHS 6 to the coolant in the tube 10. However, this heat transfer will be significantly less than in the prototype TRP with a partition, due to a significantly smaller heat exchange surface of the tube and less heating of the coolant. Thus, it will not be necessary to increase the flow rate of the coolant, and therefore, the increased cost of electricity for pumping the coolant through the core of the TRP. Thus, the effectiveness of TRP will increase.

 Due to the fact that all EHS 6 are cooled almost identically, since they have the same temperature of the coolant inlet from the distributor 11 and the coolant outlet to the collector 12, their parameters, including the average coolant temperature, can be selected as optimal. Therefore, the EHS and, accordingly, the TRP will work in optimal modes, i.e., at maximum efficiency.

 Thus, in a compact TRP of a modular scheme, in which the pipelines for supplying and discharging the coolant are located at one end of each EGP, with simplified assembly, the introduction into the active zone of the tube for supplying the coolant from one end of the TRP to the transfer distributor of the coolant located on the other end allows to increase the efficiency of electricity generation by reducing recovery in the core, ensuring the same working conditions in the cooling system of all EHS and reducing the cost of pumping the coolant.

Sources of information
1. Kuznetsov V.D., Gryaznov G.M., Artyukhov G.Ya. et al. Development and creation of a thermoemission nuclear research institute "Topaz". - Atomic Energy. 1974.V.36, issue 6. S.450-454.

 2. Patent RU 2076385 C1, MKI H 01 J 45/00. Thermal emission reactor converter. Publ. 03/27/97. Bull. 9.

 3. Patent RU 2086036 C1, MKI H 01 J 45/00. Thermal emission reactor converter. Publ. 07/27/97. Bull. 21.

 4. Bystrov P.I. et al. Development, manufacture and testing of a full-scale simulator of the power generating package of a modular space nuclear power plant with a lithium-niobium cooling system. Space rocket technology. Proceedings of RSC Energia named after S.P. Queen. Series 12: Ed. RSC Energia, Korolev Mosk. reg. 1996. Issue 2-3. S.64-69, Fig. 3.

 5. Patent RU 2172041 C1, H 01 J 45/00. G 21 D 7/04, G 21 C 3/40. Thermionic converter reactor. Publ. 08/10/2001. Bull. 22.

Claims (1)

Thermionic reactor-converter, containing an active zone of at least two power generating packages in the form of a sealed enclosure, equipped with nozzles for entering and leaving the coolant located at one of the ends, with thermoemissive power generating assemblies located inside the enclosure, dispensed and assembled coolant collectors, located at two ends of the package, and to the collection manifold is connected a pipe for the exit of the coolant, characterized in that inside each The package coaxially with the thermionic power generating assemblies has at least one pipe for supplying the coolant, one end of which is hydraulically connected to the nozzle for entering the coolant, and the other end is hydraulically connected to the distributing collector of the coolant.

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