Energy Technology – Nuclear Power
In the early days of nuclear technology, hopes were raised of unlimited energy. It did not take long for the potential dangers to be recognized, although nuclear power still supplies a portion of the world’s electricity.
Nuclear technology works by splitting atomic nuclei (fission) to release vast amounts of energy. To begin the process, neutrons bombard fissionable material such as uranium or plutonium. When a neutron hits an atom’s nucleus at just the perfect speed, the nucleus splits apart. This produces smaller atoms, more free neutrons, and energy. The free neutrons then split other nuclei, initializing a chain reaction.
A nuclear reactor’s core contains fuel rods of fissionable material bundled together. During controlled fission, moderators such as water or graphite control the neutrons’ speed and control rods slow or stop the chain reaction when necessary. The heat from fission is then collected by a coolant substance and used to drive turbines and generators.
Types of reactors
Reactors differ according to the fission process used and the materials used as rods, coolant, and moderators. Boiling water reactors have one cooling cycle; the water that cools the reactor also drives the turbines as steam. Pressurized water reactors have separate water circulation systems. “Fast breeder” reactors, with liquid sodium coolant, “breed” new fission- able material, extracting more energy from a given amount of uranium.
Pebblebed reactors, on the other hand, use helium coolant, and spheres of fissionable material instead of rods. There are various risks associated with nuclear technology and different hazards are produced by each type of reactor. In boiling water reactors, defective turbine housings can leak radioactive water into the environment from the primary circulation system.
In pebble-bed reactors, helium at over 1832°F (1000°C) can contact water, abruptly vaporize, and subse-quently explode. Even properly functioning reactors produce radioactive waste that remains dangerous to plant life, animals, and humans for thousands of years. Despitethe multitude of risks, nuclear power will continue to be used and innovations in safety mechanisms and more efficient utilization of fissionable material will constantly be discovered.
REACTOR SAFETY
Nuclear reactors pose several different kinds of risks, with the “worst case scenario” causing destruction similar to that of an atomic bomb. In addition to the direct devastation of pressure waves and fire, lasting radioactive contamination of the surrounding area is a serious threat Smaller-scale accidents may expose workers to harmful or fatal doses of radiation, and ongoing leaks of radioactivity into the environment may occur.
Finally, radioactive material may be diverted and used to construct “dirty bombs,” which even small groups can use to threaten entire metropolitan areas. At least in Western Europe, numerous measures have been put in place to increase the safety levels of nuclear plants.
However, nuclear power remains a risky technology. To date, no insurance company has been willing to protect the operators of a nuclear plant against the consequences of a meltdown: the risks are ultimately carried by society itself.