The declining reserves of fossil fuels and their detrimental effects on the environment has thrust nuclear power into the limelight as a promising option to energy-starved economies around the world. However, in the countries with a history of using nuclear power, this technology has long been mired in controversy and dispute. Proponents argue that the tiny carbon footprint of nuclear fuel, the significantly low operating costs and relatively low life-cycle costs, and the emergence of a new generation of nuclear reactors with improved safety designs justify the use of nuclear power. Opponents warn that the health and environmental risks of nuclear radiation, the possibility of catastrophic reactor accidents, the increased risks of nuclear arms proliferation and terrorism, and the lack of agreed and well-tested radioactive waste management procedures are sufficient reasons to put the brakes on building new nuclear power plants (NPP) and shut down the old ones.
In May 2009, Bangladesh signed a Memorandum of Understanding with Russia to build a two-unit NPP at Rooppur. Subsequently, the two countries signed a series of agreements, the most recent being in January 2013, to consolidate the plan for building the NPPs. As Bangladesh enters the final phases of its plan to build NPPs, there is a need to critically examine the related issues and concerns. In this article, we focus primarily on the safety issues.
A good way of understanding the safety of an NPP is to consider the likelihood and the potential consequences of a nuclear accident. According to latest estimates, out of the 437 reactors currently operating around the world, one of them is likely to have a major accident in the next 20 years. The corresponding probability of an individual reactor suffering an accident during its lifetime of 35-40 years is about 0.4%. Although this likelihood appears to be small, the astronomical magnitude of the consequences, which include large scale radioactive contamination of air, soil, water, and the biosphere, and many adverse health effects, makes this likelihood nontrivial, if not unacceptable.
There are many possible event sequences that constitute a reactor accident. One possible sequence is: the control mechanism (which regulates the rate of energy production) fails, causes the reactor to suffer a runaway chain reaction, overheats and melts the core, and evaporates the coolant. The molten core full of radioactive materials seeps through the bottom of the reactor, enters and contaminates the ground, the vegetation, rivers and water systems, and underground water tables. Furthermore, if the emergency heat removal systems also fail, overheating can build up excessive pressure inside the reactor and lead to a breach of the containment barrier, resulting in a release of radioactive gases into the atmosphere.
The most serious accidents in descending order of severity occurred at Chernobyl (Ukraine, 1986), Kyshtim (Russia, 1957), Fukushima (Japan, 2011), Three Mile Island (USA, 1979) and Seversk (Russia, 1993). The worst known reactor accident is the Chernobyl disaster. Inadequately trained personnel conducting unsafe tests on reactors (RBMK class) with a history of safety and design flaws caused the control mechanisms to fail. The resulting sequence of events led to a partial core meltdown.
After the accident, radioactive material spread over a large portion of Eastern Europe causing several short-term casualties and such long term adverse health effects as cancers and cardiovascular diseases. Those living in Bangladesh around the time of this accident might remember that the government banned the import of milk products from East-European countries because they were contaminated with radioactive material.
A 1996 study on the Probabilistic Safety Assessment of Russian Reactors done by ECONET Consulting for the Office of Environment, Nuclear Safety and Civil Protection of the European Commission notes that Russian “operating reactors were found to have significant safety deficiencies, both in design and operating practices.” The report further adds: “A comparison of the core damage frequency of the Soviet designed reactors considered in the report with some selected Western Water Pressurized Reactors shows that in general the risk of core damage is less at plants in Western countries.”
Besides RBMK, the other reactors built in Russia are the VVERs, Russian acronym for Water-cooled, Water-moderated Energy Reactor. The reactors planned to be built at Rooppur are VVER-1000s. The VVER-1000 reactors, first introduced in the 1980s, are operating now mostly in Russia and former Soviet Republics. Although improved safety features were added to theVVER-1000 reactors, controversy still surrounds them. Hungary cancelled the order of two VVER-1000s to meet a precondition for joining the European Union in 2004. After reunification in 1990, Germany discontinued construction of power plants in “East Germany” that were to use VVER-1000s.
As Bangladesh is moving forward with a plan to introduce nuclear power into its energy mix, an important question to ask is whether the VVER-1000, with significant safety concerns, is the best choice among alternative reactor designs. If the answer is yes, then the following questions need to be answered well before the first neutron hits the first uranium nucleus.
Will there be enough trained manpower with the work ethic, the discipline, and a well-internalised culture of safety required for operating an NPP? What's the status of creating an independent regulatory agency to enact and implement safety regulations for the NPP, which is absolutely essential before an NPP begins operations? In the event of an accident or radiation leak, is there a viable plan to contain the damage and the exposure, and to evacuate millions of people to a safer area? How secure will be the reactors and spent fuel facilities from terrorist attacks, political upheavals, and natural disasters? Do the citizens know the risks of living near a nuclear power plant? What is the plan for decommissioning the reactors after their useful lives of 35-40 years?
Unlike the hot ashes left over in a coal-burning furnace that can be cooled by dousing with water, radioactive “hot ashes,” in the form of fission fragments and actinides produced in the spent fuel of a reactor, cannot be cooled by water. They rid themselves of the excess energy on a time scale determined by their half-lives, the time it takes for half of their radiation to dissipate. Nuclei with half-lives less than a year do not pose waste disposal concerns because they become harmless in short order. Those with very long half-lives, e.g. millions of years, are also of little concern because they emit radiation at a negligible rate. The radioactive nuclei with half-lives somewhere between these broad limits are the ones that need to be addressed in any waste disposal scheme.
The half-life of one highly radioactive nucleus in the spent fuel, Plutonium-239, is 24,360 years. As a rule, it generally takes about ten half-lives for a radioactive nucleus to be considered safe. For plutonium, this is 243,600 years! What plan does Bangladesh have for the safe storage, transportation, and disposal of long-living and extremely hazardous radioactive wastes?
It is possible that the Bangladesh government has addressed the above issues and has answers to the above questions. But the citizens of Bangladesh, apparently, are not in the know.
Whenever a new technology is introduced, it should be done with full sensitivity to the risks it imposes on the citizenry and with their input and consent. Bangladesh government should, therefore, do a critical self introspection before jumping onto the bandwagon of NPP nations. The government should also engage a broad spectrum of its citizens in an informed debate about the pros and cons of nuclear power. Otherwise, the government will be held accountable by its citizens if it fails to contain a nuclear mishap effectively with minimal loss of human life and limited damage to the environment.
A nuclear mishap has ramifications which can extend far beyond its place of occurrence. For example, the fallout from a nuclear accident at Rooppur will affect not only the people in its immediate vicinity, but also the rest of Bangladesh and the neighbouring Indian states. The food and other goods exported from Bangladesh to other countries might also be affected by the fallout. Because of such global ramifications of a nuclear mishap, the government will also be accountable to the citizenry of the world.
The writers are Professor of Physics, Fordham University, New York and Nuclear Engineer & Energy Policy Specialist in Arlington, Virginia, respectively.