Atomic power for rockets

The heart of a nuclear-rocket engine is the reactor that converts nuclear energy into heat.

The fuel of the reactor consists of a special kind of "isotope" of ura­nium, called Uranium-235. When properly.

bombarded with neutrons, the uranium nuclei break up or "fission" into a pair of fragments and emit more neutrons in the process, thus keeping the reaction going.

The fission process releases energy and the excess energy is carried away by the neutrons and by gamma rays. Since all of the fragments and most of the neutrons and gamma rays are stopped within the reactor, the energy that is released by U-235 fission will heat the reactor.

For making a nuclear-rocket engine thermally efficient the reactor's temperature must be as high as possible. The melting point of uranium, 2,070 degrees F, sets a theoretical limit. Graphite, which withstands much higher temperatures, is a very good material for the reactor's "moderator". So all present experimental reactors for nuclear-rocket engines are made of U-235 metal powder placed in graphite.

A cold gas, the hydrogen, enters several hundred narrow passages drilled through the graphite-uranium reactor core and is heated almost to the white-hot operating temperature. On coming from the passages, the hot gas expands through a nozzle in which it attains supersonic speed.

The exhaust speed of the nuclear-rocket engine can probably reach 23,000 to 30,000 feet per second, which is twice as much as from a rocket engine using chemical combustion of hydrogen and oxygen.

Вариант 6

I. Перепишите следующие предложения, подчеркните в каждом из них герундий или причастие, определите его функцию в предложении; предложения переведите на русский язык.

1. On splitting atom in the reactor heat is developed.

2. Duplicating the extreme conditions present at the birth of the universe is very difficult.

3. The subatomic stuff got stabilized combining into particles that make up matter today.

II. Перепишите и письменно переведите на русский язык сложные предложения, содержащие придаточные предложения условия.

1. In case there is some alteration in space, the particles will react.

2. If all photons were not identical, lasers would nor operate.

3. Had no forces acted in the region, the field had got a numerical value of zero.

III. Перепишите предложения, подчеркните в каждом из них объектный или субъектный инфинитивные обороты, предложения письменно переведите на русский язык.

1. This method permitted the tests to be carried out faster.

2. The scientist considered the results to be satisfactory.

3. Change in the properties of subatomic particles is considered to be a phase change.

4. The rapid cooling is thought to have generated several phase changes.

IV. Перепишите и письменно переведите на русский язык следующий текст.

THE WORLD IS MADE OF SUBATOMIC PARTICLES

According to contemporary physicists, the world is made of several types of objects, collectively referred to as sub­atomic particles. (These particles can also be thought of as manifestations of something yet more fundamental, known as quantum fields.) There may be as many as 10**9 identical copies of some of these particles in the present universe. The forms of matter familiar to us, both living and nonliv­ing, on the earth and in the heavens, are all com­posed of various combinations of only three types of sub­atomic particles - protons, neutrons, and electrons. Dozens of other types of particles can be produced momentarily in the laboratory, however, and are thought to have existed in large numbers in the early universe.

All subatomic particles are defined by a few qualities that they may possess, such as mass, spin, and electric charge. Two particles are of the same type, if all of these qualities agree. Otherwise, they are considered to be differ­ent particles. Particles of the same type are, as far as we know, truly identical in these properties of mass, spin, and charge rather than just very similar. If all photons, the par­ticles that make up light, were not identical, lasers would not operate.

The subatomic particles readily convert into one another when they collide. The kinetic energy of motion of light particles can be converted into the energy associated with mass (rest energy) of heavy particles. In many cases, even isolated particles can convert spontaneously into others, if the latter are less massive. In all such transformations, only a few properties, such as the total electric charge, remain unchanged. The subatomic particles do not act like changeless building blocks imagined by some Greek philosophers. In the last few years physicists have realized that even which subatomic particles exist they have changed radically over the lifetime of the universe.