Some Results of an Investigation and Prospects for the Development of a High-Temperature Power Reactor with a Solid Coolant

Abstract

A validation of the possibility of developing and the basic advantages of a high-temperature nuclear reactor where the first-loop coolant is a solid are presented. The basic requirements for a solid coolant are formulated, a technology for fabricating spherical graphite particles by gas-phase pyrolytic deposition is developed, and three experimental batches are prepared. The experimental facilities for investigating the motion and heat transfer, including coolant flow stability, heat exchange, and durability, are described. The results of a determination of the heat-emission coefficient during the flow of the solid coolant in a 10-mm in diameter circular channel with warming-wall temperatures in the range 373-1073 K and flow velocities 0.1-0.22 m/sec in vacuum, argon, and helium are presented. The requirements for a 500-kW bench model, on which the basic parameters of the nuclear power system with a solid coolant are to be obtained, are formulated.If nuclear reactors are viewed as the main source of electricity and heat for purposes of global conservation of gas and oil and decreasing emissions of combustion products into the atmosphere, at least three problems must be solved:• the possibility of accidental emission must be eliminated and the escape of nuclides into the biosphere during operation of the entire chain of the nuclear cycle must be decreased; • the technological schemes for using the stores of nuclear fuel, which allow for economically competitive large-scale operation of nuclear power for a long period of time, must be validated; and • the possibility of using the nuclear components of power systems for producing nuclear weapons must be eliminated. The improvement of the currently widely used PWR is making these reactors more complicated and expensive, but nevertheless the probability of meltdown of the core of such a reactor is estimated to be 10 -5 yr -1 and the probability of radionuclides escaping over the last barrier in the form of a closed shell is 10 -7 yr. Estimates show that more than 10000 nuclear reactors will be needed to meet the world-wide demand for electricity. In this case, the probability of a serious accident with radionuclides escaping would be 10 -7 ·10 4 = 10 -3 , which is unacceptable for mankind. Accidents with escape of radionuclides beyond the last barrier must be eliminated if nuclear energy is to be used on a large scale.

Evaluation of the technological parameters of a high-temperature reactor with solid coolant in the electricity generating regime

“…Microfuel and fuel compacts based on microfuel and graphite with dimensions adopted in the GT-MGR design (12.5 mm diameter, 50 mm height) were chosen as fuel at the first stage of the investigations. The conceptual questions concerning the engineering arrangement of the reactor setup, which make it possible to implement the advantages of solid coolant in the form of small heat-carrying particles moving through the core without special orientation, including passive cooldown, are presented in [2,3].It should be noted that using a solid coolant in reactors with coarse-elemental graphite coolant was studied in 1974-1988. The conceptual ideas presented in [4][5][6][7] proposed reactors constructed with massive elements which move along a circle in a horizontal plane on special rollers and cyclically heated in the core followed by heat transferred to a secondary coolant by means of radiation.…”

“…A block diagram of a system with small, spherical, heat-carrying particles based on graphite and pyrolytic carbon and the technical aspects of such a scheme -proof that the coolant velocity can be acceptable under gravity only, experimental determination of the heat emission coefficients, preliminary studies of the durability and evaluation of the physical characteristics of the reactor facility -are presented in [1,2]. Microfuel and fuel compacts based on microfuel and graphite with dimensions adopted in the GT-MGR design (12.5 mm diameter, 50 mm height) were chosen as fuel at the first stage of the investigations.…”

Concept and salient design features of a high-temperature nuclear reactor with solid coolant

“…A brief report on the results of such investigations is given in [2]. To prove that the proposed coolant can move under gravity as a dense layer with a high velocity and to study the durability of the particles, a complex of experimental works was conducted at the Research Institute and Scientific-Industrial Association Luch.…”

“…Considering the importance of connected motion of the coolant, experiments were performed at the Research Institute and Scientific-Industrial Association Luch to determine the critical flow velocity in a 1 cm in diameter circular tube with average particle diameter d p~ 0.9 mm and real eccentricities in the range ±20% [2]. In the experiment, V cr~ 0.22 m/sec, which agrees well with relation (1 The following proposals have now been formulated for the conceptual solutions for a high-temperature nuclear reactor with a solid coolant (HRSC).…”

“…To confirm the possibility of implementing the proposed conceptual solutions in the design, we shall present some evaluated data for a concrete reactor, whose main parameters are the same as those described in [2]. For thermal power 3450 MW(t) and electric power 1500 MW(e) (gross), the parameters of the core and the main elements of the vessel are as follows.…”