Dubna Exhibit Will Feature Nuclear-Powered Engine Research

Moscow DELOVOY MIR, 8 Dec 95 p 10
by Ivan Fedik

An international symposium on "History of the Soviet Atomic Project -- 1940s-1950s" (ISAP-96) will be held in Moscow and Dubna in the spring of 1996. This project will be 50 years old. Ivan Fedik, academician of the Russian Academy of Technological Sciences, active member of the International Slavic Academy, director of the Luch SPA [Scientific-Production Association], and member of the preparation committee talks about a bright page in the history of development of nuclear science and engineering -- nuclear space projects and installations, their prospects and role in space exploration.

By the time work began on space projects in our country the atomic and hydrogen problems had already been solved, the world's first nuclear power plant was in operation, a nuclear-powered vessel and submarine fleet was being developed. But it is only a decade later that we realized the complexity of the problems tackled at that time by scientists and engineers.

Development of nuclear-powered rocket engines (NRE) in the USSR began in 1959 when I. V. Kurchatov, S. P. Korolev and V. M. Keldysh met to discuss the possibility of developing a rocket with a nuclear-powered engine. By that time earth satellites had already been launched, the USSR was first in space and it seemed logical for it to want to be the first also in the flight to Mars and other planets making use of atomic power.

From the very beginning two conceptions of an engine were delineated: heating gas directly in a reactor and its release through a nozzle creating reaction thrust. The second route involved development of space nuclear electric installations powered by different types of electric engines which serviced onboard equipment. The first version was executed under ground-based conditions.

Scientists were confronted with complicated scientific engineering problems, solution of which required involvement of large groups of research institutes, design offices and plants, as well as development of new enterprises and a powerful test-stand base to refine elements, reactors and the nuclear engines proper. This problem led to creation of the Podolsk Technological Research Institute, and its successor at the present time is the research institute's Luch SPA. Without going into the structural details of the reactor-engine proper, let me mention the basic principles that advanced us to the fore and enabled us to overtake the United States for many years.

The first is development of a fuel-channel type reactor consisting of numerous identical heat-producing assemblies, which saved both time and resources for refining the reactor one assembly at a time. The second is the use of more refractory and hydrogen- resistant carbides and carbidographites of zirconium, niobium and uranium for the heat-producing elements and, in part, for insulation.

The more than 15 full scale NRE tests yield results that were considerably superior to the American achievements with graphite zones.

It should be noted that throughout the testing period, the emission of radioactive fission fragments never exceeded the permissible standards either on the testing grounds or beyond them, and never recorded on the territory of adjacent countries.

But the most important thing is that the bases for technology of such reactors were developed in Russia, and new refractory materials were obtained, while the very fact of developing the reactor-engine generated a number of new promising projects and ideas.

Among them we should mention the project for developing an aerospace aircraft with a 7500 MW NRE. Such an aircraft was to use chemical fuel at first for horizontal take-off and then nuclear power would take over. This suggestion is being discussed as one of the solutions to the problem of restoring the ozone layer of earth's atmosphere. Work is in progress to develop dual-purpose reactors that could function both as an engine and as a generator of electric power. It is assumed that the future of space energy lies precisely in such bimodal reactor installations.

The Romashka installation was the beginning of space nuclear power sources. It is a high-temperature installation without forced cooling, in which heat is transmitted from the active zone to thermoelectric converters that produce electric power. This installation has operated on a test stand for more than 15,000 hours and confirmed conclusions as to the high reliability and feasibility of using such reactors in space. This happened more than 30 years ago.

It was followed by the Buk type installation with fast reactor and two heat-carrying circuits. One transmits heat from the reactor to a thermoelectric generator and the other removes heat from the generator into space. Their electric power constituted about 3 kW and service life is up to 4 months. Let me note that this source of electricity coped brilliantly with the problem of on-board power in special- purpose satellites.

Soon this power source was replaced by a number of Topaz type thermionic emission converters of nuclear power into electric power. Stronger, small and light-weight power sources with a long service life (5-7 or more years) were needed. The thermionic emission method of converting energy could meet these requirements.

Russia is a participant in the international Topaz thermionic emission program, in which the United States, England and France are also participating.

Moderate- and high-power thermionic emission nuclear installations with unified multicomponent EGK are being developed with parameters 2-3 times superior to existing ones.

It is also planned to use these developments for space and ground-based solar power. As a result of conversion the best advances in NRE technology and thermionic emission found application in development of new chemical power sources, electric batteries and heat generators, equipment for the electronics industry, etc.

NRE and nuclear power installations do not exhaust the aggregate of space nuclear power. The tempting idea of using nuclear energy to generate lasers is already being explored on the ground. For example, a laser was developed with heat-driven gas mixture. A project was elaborated and trials have begun of an experimental laser unit with nuclear drive. This is a real prospect of obtaining a short- wave radiation spectrum.

Space nuclear power engineering has been absorbing the latest advances in science and engineering. In addition to prestige and pride of Russian science for future technological progress, space nuclear power engineering has created strong prerequisites for high-temperature power engineering in general and development of new heat- resistant ceramic materials in particular. In essence, everything that has been discussed is dual-purpose technology. It can be stated that space power engineering is a pearl in the crown of Russian science and technology. Space exploration is no a whim of scientists, it is a guarantee of national security and of Russian might.

Photo [not reproduced] depicts Ivan Fedik.