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Nuclear Reactors around the World

There are currently 450 nuclear reactors operating worldwide, and 60 more are under construction. The United States leads the list with 99 operating reactors and four reactors under construction. Following the US is France, which operates 58 reactors and is building one new facility. Japan, even after the Fukushima nuclear disaster in 2011, operates 41 reactors and is building two new ones. China operates 36 nuclear reactors and is now building more plants than any other country, with 20 reactors currently under construction. Russia operates 36 reactors and is building seven; South Korea operates 25 reactors and is building three; and India closes the list of leading countries: it operates 22 reactors and is building five. Most European countries are not constructing new reactors due to political oppositions and pressures.

Chernobyl is not Alone

In March 1979, an accident occurred at one of the two reactors at the Three Mile Island Nuclear Generating Station in Pennsylvania. As a result of a failure in the reactor’s secondary cooling system, the turbine, the generator, and finally the reactor itself stopped working and the pressure in the main system rose rapidly. A pressure valve in the reactor was designed to open when the pressure rises and close when the pressure drops, but it failed to close when the pressure dropped. The sensor reported to the control room that the system was full of water even though the coolant was rapidly emptying. The emergency cooling system in the reactor operated properly, but due to an error by the control room operator, this system was shut off. Without coolant, the temperature in the reactor core kept rising, and approximately two hours after the initial failure, the reactor dome exploded, and radioactive elements were released into the system. Thanks to the design of the American reactors and those of Western countries - unlike with the Chernobyl nuclear disaster seven years later - the radioactive substances were trapped in the reactor’s containment building. A series of conclusions were drawn from this nuclear accident, primarily those relating to human error under crisis, and those relating to reactor operation and technological changes that must be implemented from there on.

The nuclear disaster in April 1986 in the reactor at the Chernobyl Nuclear Power Plant in northwest Ukraine was the worst nuclear accident in the 20^th century. During a safety drill simulating an electrical power outage to test whether coolant circulation is maintained until the back-up generators could provide power, an unusual rise in temperature of the reactor core occurred in reactor number 4, causing a meltdown and damaging the containment vessel. Several factors are deemed to be the causes for the disaster: the design flaws in the Soviet reactors; failure to follow procedures; the operators’ incorrect understanding of the situation; and the faulty design of the emergency shut-down mechanism. The attempts to shut down the reactor failed, and the rise in temperature caused two explosions in the reactor core and a meltdown. The faulty design of the containment vessel, which was supposed to prevent radioactive substances from being released into the air, and an uncontrolled fire, caused the dispersion of a huge quantity of radioactive substances into the atmosphere.

The Soviet authorities began evacuating people from the area adjacent to the reactor only 36 hours after the accident; only as late as one month after the accident were all residents within a 30-kilometer radius of the reactor evacuated. Many of the liquidators – civil and military professionals who were drafted to handle the disaster and its repercussions – were also exposed to radiation. Several thousands of these liquidators – physicians, engineers, technicians, civil defense and security personnel, and operations personnel – came to Israel in the large immigration wave from the former Soviet Union in the early 1990s. In 2001, the Israeli parliament enacted the Chernobyl Liquidators Law, which defined criteria for recognizing liquidators and providing them with medical care and assistance with various matters – but the law has been implemented only partially. There are currently about 1,400 liquidators living in Israel, but unlike their colleagues who remained in the former Soviet Union and were recognized as heroes, those who immigrated to Israel have been forced to file a number of successive petitions to the Supreme Court to enforce the law and be granted their rights.

In March 2011, 27 years after the Chernobyl disaster, a series of accidents occurred at the Fukushima Nuclear Power Plant in Japan, where three out of six reactors designed by General Electric were in operation. The reactors were automatically shut down when the earthquake hit, and the emergency generators were activated in order to operate the coolant and control systems. The ensuing tsunami caused by the earthquake cut the connection between the reactors and the power grid and flooded the emergency generator rooms. Once the generators stopped operating, the electric pumps stopped pumping coolant to the reactors and caused reactor overheating. As a result of the earthquake and the flooding in the area surrounding the reactors, external aid personnel were unable to reach the area. The intense heat in the reactors caused meltdowns of the reactor cores. When the power plant personnel tried to cool the reactors and shut them down, several hydrogen explosions occurred. Due to the concerns over radioactive substances that might be released into the environment, the local population was evacuated. Once power was restored to some of the reactors, they were gradually reconnected and the automatic cooling pumps were operated to cool the reactor interiors and the fuel rods in the fuel storage pools, which were out of order, having been cooled with seawater in an attempt to prevent overheating.

The reactors at the Fukushima Power Plant were designed to withstand an earthquake, a frequent phenomenon in Japan, but not to withstand an extremely powerful and destructive tsunami. Due to Japan’s dependence on energy sources, it cannot stop operating the reactors that were not damaged, and it is continuing to construct new nuclear power plants.

Advantages and Disadvantages of Nuclear Energy

Notwithstanding the major accidents, nuclear energy is, for the most part, considered clean, stable, and reliable. Proponents of the use of nuclear energy claim that its cost is relatively low, the reprocessing of the irradiated reactor fuel reduces costs even more, it provides a stable infrastructure for a country’s energy economy, and it emits a low level of environmental pollution while generating fuel that will be available for many years. Nuclear power supporters also rationalize that compared to other sources of energy, this is a concentrated source, which integrates easily in the national power grid using familiar existing technology. Finally, they claim that the average citizen is exposed to a minimal level of radiation.

The principal disadvantages of nuclear energy are led by the constant threat to the environment: nuclear energy emits radiation that is harmful and can cause cancer, the nuclear fuel waste is liable to contaminate the groundwater, and solutions are needed for long term storage of the used reactor fuel. Furthermore, nuclear power plants constitute a target for an attack on a country’s infrastructure, and irradiated reactor fuel is liable to be used to manufacture an atomic weapon.

Opponents also warn that commercial reactors might undergo conversion into “military” reactors, while exploiting the plutonium from the used reactor fuel, thus using it to make nuclear weapons. Such a conversion is theoretically possible, but is neither practical nor economic for several reasons: chemical plants must be constructed for this at an enormous investment; such a course of action cannot be concealed; it is a violation of the Nuclear Non-Proliferation Treaty (NPT). We are unaware of even one instance of such a conversion.

Nuclear Reactors: Interim Solution

The massive development of alternative sources of energy will take many years, and it will take even longer until the assimilation of alternative energy sources can meet the growing consumption needs and offer economic energy solutions. A realistic look at the balance of global energy sources indicates that nuclear energy is important as an available and reliable interim solution.

Most of the attention of supporters and opponents alike is directed toward the nuclear reactors and the ways to ensure that they operate with failsafe mechanisms. The new Generation III, and lately, Generation IV reactors that are currently constructed are safer. They are also more efficient and more economic than the older reactors.

Other troubling problems are the handling and neutralizing of irradiated nuclear fuel, which contains highly radioactive isotopes and keeps discharging heat, as well as the accumulating quantities of nuclear waste. The half-lives of some isotypes are dozens of years. If the process of wide-scale adoption of nuclear energy continues until an adequate, efficient, and economic volume of alternative energy sources are available years from now, suitable nuclear waste storage solutions will become an essential task that must be addressed seriously.

The full lifespan of a nuclear reactor is customarily considered to be 40 years; however, a reactor’s lifespan may be doubled through improvements and upgrades without diminishing its safety.

The Israeli Case

Nuclear operations are conducted at the Atomic Energy Commission’s Nahal Soreq Research Center and at the Negev Nuclear Research Center near Dimona. The degree of risk posed by the research activities in both Dimona and in Soreq is not similar to the risk posed by power plants for electricity generation. Even if malfunctions occur, their potential magnitude can in no way be compared to the magnitude of those referred to above. Special attention is devoted to safe storage and continuous cooling of the spent reactor fuel that continues to emit radiation and decay heat.

The quantity of fissile material in the reactor in Dimona is smaller by two orders of magnitude than that of a reactor for electricity generation with an output of 1,000 megawatts, and, at the Soreq Center, even less, about 5 megawatts. The reactor in Dimona, constructed inside a containment building, is maintained and upgraded until it will ultimately be shut down and replaced with a new system. The plant undergoes routine periodic shutdowns for testing and maintenance, which have included replacements of many components, such as valves, coolant pipes, and more. The condition of the steel tank that houses the nuclear fuel rods and the neutron absorber is tested during every maintenance cycle. On the day that the reactor experts assess that the tank is liable to jeopardize the safety of the reactor, the entire reactor will be shut down.