Safety of Nuclear Power Reactors

July 2015 by Ball Roberts

http://www.world-nuclear.org

In the 1950s attention turned to harnessing the power of the atom in a controlled way, as demonstrated at Chicago in 1942 and subsequently for military research, and applying the steady heat yield to generate electricity. This naturally gave rise to concerns about accidents and their possible effects. However, with nuclear power safety depends on much the same factors as in any comparable industry: intelligent planning, proper design with conservative margins and back-up systems, high-quality components and a well-developed safety culture in operations.

A particular nuclear scenario was loss of cooling which resulted in melting of the nuclear reactor core, and this motivated studies on both the physical and chemical possibilities as well as the biological effects of any dispersed radioactivity. Those responsible for nuclear power technology in the West devoted extraordinary effort to ensuring that a meltdown of the reactor core would not take place, since it was assumed that a meltdown of the core would create a major public hazard, and if uncontained, a tragic accident with likely multiple fatalities.

In avoiding such accidents the industry has been very successful. In over 16,000 cumulative reactor-years of commercial operation in 32 countries, there have been only three major accidents to nuclear power plants:

Three Mile Island (USA 1979) where the reactor was severely damaged but radiation was contained and there were no adverse health or environmental consequences

Chernobyl (Ukraine 1986) where the destruction of the reactor by steam explosion and fire killed 31 people and had significant health and environmental consequences. The death toll has since increased to about 56.

Fukushima (Japan 2011) where three old reactors (together with a fourth) were written off and the effects of loss of cooling due to a huge tsunami were inadequately contained.

Apart from Chernobyl, no nuclear workers or members of the public have ever died as a result of exposure to radiation due to a commercial nuclear reactor incident. Most of the serious radiological injuries and deaths that occur each year are the result of large uncontrolled radiation sources, such as abandoned medical or industrial equipment.

It should be emphasised that a commercial-type power reactor simply cannot under any circumstances explode like a nuclear bomb - the fuel is not enriched beyond about 5%, and much higher enrichment is needed for explosives.

The International Atomic Energy Agency (IAEA) was set up by the United Nations in 1957. One of its functions was to act as an auditor of world nuclear safety, and this role was increased greatly following the Chernobyl accident. It prescribes safety procedures and the reporting of even minor incidents.

While nuclear power plants are designed to be safe in their operation and safe in the event of any malfunction or accident, no industrial activity can be represented as entirely risk-free. Incidents and accidents may happen, and as in other industries, will lead to progressive improvement in safety. Those improvements are both in new designs, and in upgrading of existing plants.

The safety of operating staff is a prime concern in nuclear plants. Radiation exposure is minimised by the use of remote handling equipment for many operations in the core of the reactor. Other controls include physical shielding and limiting the time workers spend in areas with significant radiation levels. These are supported by continuous monitoring of individual doses and of the work environment to ensure very low radiation exposure compared with other industries.

Сопоставьте части предложений. Переведите предложения письменно.

1. Those responsible for nuclear power technology in the West devoted 2. One of its functions was 3. Radiation exposure is minimised by 4. Those improvements are both in

a. the use of remote handling equipment for many operations in the core of the reactor. b. new designs, and in upgrading of existing plants. c. to act as an auditor of world nuclear safety. d. extraordinary effort to ensuring that a meltdown of the reactor core would not take place.

8. Прочитайте текст и ответьте письменно на вопросы:

1. What naturally gave rise to concerns about accidents and their possible effects?

2. What factors are the main ones in nuclear power safety?

3. What three major accidents to nuclear power plants do you know?

4. What are the reasons of serious radiological injuries and deaths that occur each year?

5. What is The International Atomic Energy Agency?

Заполните пропуски данными словами (core, steam explosion, low radiation, progressive improvement, destruction, radiation exposure, doses, health and environmental consequences). Переведите предложения на русский язык.

1. Chernobyl (Ukraine 1986) where the a)……..of the reactor by b)……..and fire killed 31 people and had significant.c)……..

2. Incidents and accidents may happen, and as in other industries, will lead to d)…… in safety.

3. E)……..is minimised by the use of remote handling equipment for many operations in the f)…….of the reactor.

4. These are supported by continuous monitoring of individual g)…….and of the work environment to ensure very h)……..exposure compared with other industries.