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The gas turbine-modular helium reactor (GT-MHR) is a promising power reactor for the next century. The project is based on experience gained from the operation of more than 50 gas-cooled reactors using CO 2 and helium coolant as well on as the latest advances in the implementation of the direct gas-turbine Brayton cycle.Five helium-cooled reactors, which were operated in the USA and Germany from 1960 to 1980, demonstrated their intrinsic properties that can meet the most stringent safety requirements. Experiments performed on the AVR (Germany) showed that reactors with a moderate energy intensity (up to 3-4 MW/cm 3) cool without the intervention of active systems and action by an operator. The operation of those five reactors (Dragon, Peach Bottom, Fort St. Vrain, THTR-300, AVR) also demonstrated that the refractory-coated particle fuel is capable of high burn-up.By 1990 the advances in the technology for gas turbine equipment, high-efficiency recuperators, and magnetic bearings made it possible to consider a reactor facility that would combine a safe modular gas-cooled reactor and an energy conversion system operating on the high-efficiency Brayton cycle.The international GT-MHR project under way now is characterized by: -greater safety than that of other reactor concepts, namely, meltdown of the fuel and the core as a whole cannot take place; -a high energy conversion factor; -competitiveness on the electricity generation market; -high radiation stability of the fuel, including discharged fuel, whereby it can be stored without further processing; and considerably lower environmental impact than that of other reactor facilities (50% smaller heat load on the environment and 75 % less heavy metals in the wastes).The GT-MHR can be used for effective consumption of weapons-grade plutonium with an attendant generation of electricity.The Reactor Facility (Fig. l). The facility incorporates a modular reactor with a high-efficiency gas-turbine system for thermal energy conversion, which are in two vessels and connected by a horizontal conduit. The reactor module is below ground in a cylindrical concrete vessel. It uses fuel microfueI elements with a multiple-layer coating, which retains fission products, containing fuel cores of fissile material surrounded by four ceramic layers. Closest to the core is a buffer layer of low-density pyrolytic carbon (-1 g/cm 3) acts as a collector of gaseous fission products. The next layers, a dense layer of pyrolytic carbon (7 = 1.8 g/cm 3) and a layer of silicon carbide, are barriers for retaining gaseous and volatile fission products. Comprehensive research on such fuel carried out in the United States, Germany, Japan, and Russia over the past 20 years has made it possible to develop a technology for producing such fuel. The outside diameter of the microfuel elements is -620 /.tm. The fuel particles are pressed into a cylindrical fuel compact of diameter -12.5 mm and height 50 mm. Synthetic graphite is used as the matrix. The microfuel elements occupy -15% of the volume of the fuel c...

High-temperature helium-cooled reactors are the best understood nuclear technology that can supply high-temperature heat for thermal processes for producing hydrogen. The GT-MGR reactor -an innovative international modular design of a helium-cooled reactor with a gas-turbine cycle -best meets the requirements for hydrogen production and is proposed as a basis for a nuclear energy source. In this paper, the technical aspects of the proposed application of HTGR as a source of energy for producing hydrogen are analyzed. The required parameters of the energy obtained from HTGR for the presently completed and future hydrogen-production technology are examined. The problems and additional R&D work on the use of HTGR at high helium temperatures are indicated.Today, fossil fuels are mainly used in industry, for transportation, and for generating electricity. At the current rates of consumption, the stores of fossil fuel are sufficient for no more than several hundreds of years. It would be shortsighted to use up all of the available reserves of fossil fuels just to meet the increase in demand.The most efficient method for meeting increasing energy needs could be to convert nuclear power into electricity and hydrogen as the most effective and universal energy carriers. HTGR is a nuclear technology that can supply high-temperature heat for producing hydrogen. HTGR technology is highly safe and efficiently produces electricity while keeping environmental effects to a minimum.Today, the electrolysis of water and steam conversion of methane for subsequent stages -thermochemical decomposition of water and high-temperature electrolysis of water vapor -are the main technology which has been investigated and mastered by industry for producing hydrogen using energy from HTGRs. The main requirement for the source of high-temperature heat for producing hydrogen is that the coolant be heated up to 1000°C with pressures up to 5-7 MPa.Nuclear reactor designers became interested in high-temperature helium-cooled reactors more than 40 years ago because of the new possibility for heating the helium at the reactor exit up to 1000°C and the enhanced safety of the reactor. The first successes were achieved in the mid-1960s: experimental low-power reactors were developed -Dragon in Great Britain, the Pitch-Bottom nuclear power plant in the USA, and AVR in Germany. The first two reactors operated for more than 10 yr, and the last one operated for more than 20 yr, showing reliability, high readiness and safety, low radioactive contamination of the first loop, stability in transient regimes, and the capability of heating helium up to 950°C for a long time.

Historical information concerning the development of high-temperature gas-cooled reactors in the USA and Russia is presented. The reactor facilities MHTGR (USA), , VGM (Russia), GT-MGR (Russia, USA), and at the Fort St. Vrain nuclear power plant (USA) are described. The US programs for developing innovative high-temperature nuclear reactor technologies are examined. It is shown that the Russian and US technological developments for the fuel, reactor system, energy conversion system, and fission-product transport are similar.Analysis of world energy consumption with limited resources for conventional power generation shows that intensive economic development is impossible without the establishment of large-scale nuclear power capable of supplying the energy required for a substantial part of the growth in energy needs. At the present time, the largest amount of fuel-energy resources, including the most expensive and scarce -oil and gas, is used for producing heat with diverse potentials, approximately three times more than for electricity production [1, 2]. The expansion of nuclear power into high-temperature industrial production, where the scarcity of fossil fuel is even more acutely felt than in the production of electricity, can be attained by bringing high-temperature gas-cooled reactors (HTGR) which are capable of generating high-potential heat, into the nuclear power system. HTGR Development in the USA and Russia. HTGR use fuel with specific qualities as compared with other types of reactors; it contains spherical fuel pellets or fuel blocks containing fuel compacts. The foundation of the fuel composition is microfuel containing a spherical kernel with ceramic multilayer coatings, which are the main barriers for confining fission products. The first US facility with an experimental reactor, developed by the General Atomics Company, was introduced in 1967 at the Peach Bottom 115 MW(t) nuclear power plant. The objective was to demonstrate the possibilities of using HTGR for commercial production of electricity with high-temperature steam and to obtain the experience required for developing a more powerful nuclear power plant. The problem of developing a reactor with high fuel burnup (75 MW·days/kg) was posed at the same time. Thirty-three fuel modifications, including the fuel rods at the Fort St. Vrain nuclear power plant, were tested [3].The pilot nuclear power plant at Fort St. Vrain with a high-temperature gas-cooled reactor was put into operation in 1976. The main equipment in the first loop of the facility consisted of a 842 MW(t) reactor with a core comprised of prismatic fuel assemblies, steam-generators, and axial gas blowers with steam-turbine drive placed beneath the core in a vessel