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УРОК ДЕВЯТЫЙ

Текст: Nuclear Power for Aircraft. Грамматические основы перевода

Слова и словосочетания, служащие для связи частей высказывания (§ 68-74).

Лексические основы перевода

Перевод слов; sure, assembly, former, latter. Перевод союза while. Перевод предлога with.

Перевод многозначных служебных слов: also, again, otherwise, rather, yet, still, then (упр. 5-8).

Перевод слов с различными суффиксами и префиксами (упр. 17). Перевод наречий с суффиксом wise (упр. 18).

Перевод терминов типа «существительное + причастие II», соединенных дефисом (упр. 19).

ТЕКСТ

NUCLEAR POWER FOR AIRCRAFT

The chief attraction of the nuclear-powered aircraft appears to be the prospect* of virtually unlimited range.

To begin with2, the extremely high heat values of nuclear fuel are tens of thousands of times greater than chemical fuel, and the consumption is very small which would ensure long range; and flight round the 25,000-mile circumference * of the earth without refuelling would be an easy task.

Again*, the advantage offered by nuclear power of long endurance* would enable an aircraft to be kept flying for very long periods. In consequence*, such an aircraft carrying early warning radar** would be invaluable in an air defence system.

• circumference - окружность early warning radar - радиолокационная станция дальнего обнаружения



It seems likely, however, that the weight of shielding« required would result in a very large aircraft in which high percentage* power plant would pose difficult design problems, published «• estimates for aii-up " weight varying from 250,000 to 500,000 lb. There will be concentration of weight in the fuselage unless it is found possible to locate the payload in the wings, which will not be otherwise" required (for large volumes" of chemical fuel). Then", for shielding purposes the tendency will be to place the aircrew as far forward as possible, with the payload and undercarriage, etc. between them and the power plant. The reactor shield assembly of the power plant will weigh up to 100,000 lb. with a density of about 150 Ib./cu. ft, or some six times that of a turbojet engine. This will give rise to special structural problems.

It seems likely that the first nuclear power plants would be based largely on existing gas turbine practice, replacing" the combustion chamber by a heat exchanger designed to transfer heat to the engine air from a secondary fluid which would draw its heat from the atomic pile *

Furthermore, the nuclear power plant problem Is not only one of flight. It is known that when a reactor is shut down and the fission process stops, considerable heat continues to be generated by the decay 20 of fission products. This phenomenon is called "afterheat," * and although it steadily decreases, the amount of heat during the first week is great enough to require forced cooling for the core " not to melt and destroy the reactor. The difficulty can doubtless be overcome, yet an accident 22 involving the stopping of the engine will present a situation where the afterheat will undoubtedly damage the core, with the consequent generation of harmful by-products **.

Still, some advantages in aircraft design accompany" the use of atomic fuel. First of all, the concentration of loads eases25 the problem of structural design. Then, greatly reduced is the fire risk, since the amount of chemical fuel carried, when nuclear power is used, is only adequate to give satisfactory conditions for take-off and landing. Ontheotherhand, a nuclear-powered aircraft has to land with the same weight as it takes off, and there are many unknown factors, such as the effect of radiation on the materials used in its construction. As regards the former, suggestions have been made to use jet-lift engines (oil-fuelled) to provide vertical take-off and landing; concerning the latter little is yet known about changes in aircraft materials in such circumstances 2*.

In short", while28 nuclear reactors offer the possibility of specific impulses approximately twice as great as those of the heat chemical systems, they have several potential disadvantages that

♦ afterheat - радиоактивный распад ** by-products - продукты распада



must be considered and minimized where possible. These are reactor weight, problems involved in neutronic start-up and control and the intense radiation field during power operation. Fli r t h e r, the inherent reliability of such systems is an unknown quality, although assumptions regarding reliability must be made in choosing 28 one reactor design over another.

To sum up, it seems certain that a nuclear-powered aircraft can be constructed and flown, but whether it will prove too cumbersome *, too dangerous, and too expensive" to operate are questions which have yet to be answered.

УПРАЖНЕНИЯ

Грамматические упражнения

1. Переведите предложения, обращая внимание на перевод выделенных средств связи типа in (by) contrast (<н наоборот», «напротив», § 71).

in (by) contrast

1. Pluto is so far away from the Sun that the Sun looks no larger in its sky than a star does to us. On Mercury, by contrast, the Sun would nearly fill the sky.

2. The principles of dynamics had been summed up by Newton as early as 1687. In contrast, the other primary branches of physics - heat, light, electricity, etc. - did not begin to assume their modern forms until the nineteenth century.

on the contrary

3. The natural tendency of heat to flow from a higher to a lower temperature makes it possible foe a heat engine to transform heat into work. On the contrary, a mechanical refrigerating machine must transfer heat from a colder to a hotter body.

conversely

4. Steady flow exists if the velocity at a point remains constant with respect to time. Conversely, unsteady flow exists if the velocity changes either in magnitude or in direction with respect to time.

5. If an air mass is moved from a position near the ground to a higher position, the reduced surrounding pressure results in an expansion, which in turn causes a cooling of the air. Conversely, if an air mass is brought to a lower elevation of greater pressure, it is compressed and the temperature increases.

alternatively

6. The cathode of a two-electrode valve * sometimes consists of a filament 2 which is directly heated by an electric current. Alternatively, it may be a metal cylinder which is indirectly heated by radiation or conduction.

* cumbersome - громоздкий

* valve - радиолампа

filament- нить накала



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