Mainstream, VOL LII No 51, December 13, 2014
Safe Nuclear Power — Fact And Myth
Monday 15 December 2014, by
The nuclear energy programmes of many countries are either at a standstill or are actually declining. Prominent among these are the USA, Sweden and Denmark, and most recently Germany. The reasons for this are to be found solely in public awareness of the dangers of catastrophic accidents and of long-term risks of continued low-level radiation from normal operation of nuclear installations.
The Departments of Atomic Energy (DAE) of all countries are duty-bound to encourage the use of nuclear energy and ensure the safe operation of nuclear power plants (NPPs). Thus in the execution of their duties, they tend to gloss over the problems of operational safety, try to allay fears that routine operation is not clean, and aver that nuclear power is cheap. In fact the platform of the DAE is perched on a three-legged stool of “safe-clean-cheap” nuclear power. It must be recognised that especially in the case of nuclear power, these three factors are very closely inter-related since, for example, strict adherence to safety requirements leads to frequent shut-downs and adversely affects operating costs.
It is fairly obvious that in the closed-door system within which the DAE functions, the safety compromises which may have been made will not be allowed to come to public notice. Also, since radioactivity cannot be felt or otherwise sensed by humans, and since the common understanding of “clean” is freedom from smoke, smell, dust etc., the environs of a nuclear installation are considered clean.
In the conventional sense NPPs certainly are clean when compared to a thermal power plant. But NPPs are not conventional. They are the source of radioactivity (either planned/routine discharges or accidental/incidental leakages) which eventually reach the public at large through the air, water or food chain. Thus to use the word “clean” with regard to nuclear installations is entirely misleading to common understanding.
The DAE has attempted to quantify the risk with respect to nuclear energy, quoting some statistics provided by the Chairman of the CEGB, UK, regarding the relative risks of common activities such as smoking and of release of radioativity from NPPs. The risks of low-level radiation are not known and indeed the DAE admits that “data on radiation-induced genetic damage leading to diseases is extremely scarce”. It is not at all clear how the DAE can maintain that nuclear plants are safe if data on the subject are scarce. To give an example of long-term effects in the pharmaceutical field, we have the case of the tranquiliser drug, thalidomide, which was prescribed in Europe in the 1960s to pregnant women. It resulted in phocomelia (children born without limbs) and the drug was banned in the 1970s after irreversible damage had been done. Cases of physical and genetic damage to workers in uranium mines, rare earth processing factories and NPPs all over the world are known. The crux of the point regarding nuclear risk when compared with smoking is that smoking is a voluntary activity (for the smoker) and smoke and smell can be avoided by non-smokers, whereas the location and operation of nuclear installations are imposed upon the public, and radioactivity cannot be seen, smelt or felt and hence cannot be avoided. The comparison is facile and the argument is specious. And all this is in regard to routine operation of NPPs.
Quite apart from the risks of long-term exposure to low-level ionising radiation discussed above, the risks of accident at NPPs are not negligible and are certainly not inconsequential. The viability of any source of power is a marriage of cost-effectiveness and safety (which is really implicit in a social cost). NPPs of the so-called conventional types, namely, the pressurised water reactor (PWR) and the boiling water reactor (BWR), run the finite risk of accident due to steam or hydrogen explosion up to about 1000 kg TNT equivalent, which can rupture even a concrete double containment.
The DAE has not conducted any independent studies of nuclear accident sequences and assumes the published results of design basis accident (DBA) predictions from foreign countries. Technical success, even repeated technical success, does not imply reduction of accident risk and can in fact mask minor deficiencies which over time add up to major disasters. The US space programme, which was proceeding with all outward signs of success, suffered a major setback when space shuttle Columbia exploded in 1985 due to failure of a rubber seal made by Morton Thiokol. If, with a handful of NPPs in India we have no news of accidents, it is because security rules prevent the DAE from informing the public.
An official of the DAE has stated that with a triplicated emergency core cooling system (ECCS) installed in a nuclear reactor, core heat-up is “inconceivable”. A major accident is precisely what may be considered inconceivable. The DAE works on the basis of certain design basis accidents (DBAs) but not on a worst possible accident (WPA) which can result from a power excursion accident (PEA) coupled with ECCS failure, or a power-cooling mismatch accident (PCMA) linked with an unconnected turbine trip event.
Not even the USA can design for a WPA and it is this reason that has caused public opinion to force New York Mayor Ed Koch to order the abandonment of a completed billion-dollar NPP without a single day’s operation. They have learnt from the Three Mile Island (TMI) accident and others, but our DAE is not considering the lessons learnt in foreign practice while implementing our own nuclear power programme.
The much touted fast breeder reactor (FBR) is being planned in a 500 MW prototype. The FBR is even more unsafe than a PWR or BWR since it can explode like a nuclear bomb. The fuel in a PWR or BWR reduces in reactivity with increasing compaction and hence can cause only(!) a steam or hydrogen explosion. But in an FBR, compaction of fuel after a partial melt-down raises the reactivity and results in explosion of the nuclear weapon variety. Also the FBR fuel is very highly toxic compared to the PWR/BWR fuel and its dispersion in the atmosphere as a result of accident will be much more harmful. India’s FBR programme must be reviewed particularly on account of the safety problem and since the resulting plutonium is the stuff which nuclear weapons are made of.
The DAE sets store by “defence in depth” with regard to safety in operation of NPPs. The principle of “defence in depth” is not a speciality of NPPs nor an innovation of nuclear scientists. It is nothing but system redundancy as provided in many electro-mechanical devices such as aircraft. The satisfactory design and functioning of safety systems depends upon the anticipated series of failure events. The DAE mentions the four “barriers that would have to be simulta-neously breached” as defence in depth; however, their breaching in series, which is much more likely, has not been considered.
Next, let us take one possible PWR accident scenario. Non-uniform fuel pellets in the zircalloy cladding cause a small local over-heating of fuel rods and a local power-cooling mismatch, perhaps aggravated by inaccurately positioned control rods. One or more control rods get ejected and a sharp increase in local heat is the result. One or more fuel rods melt out of shape and restrict the flow of the coolant, thereby causing a localised steam explosion and damaging other fuel rods. All this may take place before the ECCS or SCRAM are activated automatically.
This situation leads to a power excursion which raises the pressure beyond the venting capacity of relief valves and results in a major steam explosion which ruptures the reactor vessel and starts a core meltdown, taking the situation out of control. A perusal of the book, The Accident Hazards of Nuclear Power Plants by Richard E. Webb (who holds a Ph.D in nuclear engineering), and a viewing of the feature film, The China Syndrome (incidentally released a few days before the Three Mile Island accident), will bring out the above and other possible scenarios.
The present-day design of nuclear safety systems is based on single failure accidents which are called DBAs. The design against a WPA involving multiple failures either in cascade or by random events (such as occurred at the TMI when an operator shut off the ECCS for reasons unknown) is not within the scope of reactor design.
Nuclear engineers are hard put to provide system redundancies and more safeties which make the system more complicated, without further raising the cost of generated power due to frequent tripping and high initial cost. Even the present trade-off between the cost of nuclear power and and the social and actual costs of low-level radiation, waste management, plant de-commissioning and nuclear accident is unfavourable. Any detailed cost-benefit analysis in respect of nuclear power in India will reveal that even with the current (inadequate) safety practices, the cost of power is more than from the thermal power stations. There is, however, no public non-governmental body which can do this formally, and finally dispel the DAE’s myth that nuclear power is safe, clean and cheap.
The DAE maintains that the TMI (1971) and Chernobyl (1986) were both caused by human error in operation. The Chernobyl accident was certainly due to human error in that certain safeties were manually over-ridden. But the TMI accident was not due to human error; human error was not the causative factor even though it was involved in the chain of events. At any rate, our NPP staff at all levels are at least as prone to human error as their counterparts in the USA or erstwhile USSR. In the TMI accident a partial meltdown occurred and while the reactor vessel and containment did not rupture, 250,000 gallons (1.12 million litres) of radioactive water was dumped into the Susquehanna river without informing the public. The nuclear industry in the USA has not till date recovered from this accident.
It is clear that the DAE will support nuclear power for reasons of policy, for that is their raison d’etre. Any information which can reveal conclusively that nuclear power (a) is not cheap, (b) has long-term social costs that a poor nation cannot bear, and (c) has serious accident risk in the context of an industrially developing country which is very densely populated, will be jealously guarded by the DAE.
On the other hand, the anti-nuclear activists are resorting to sniping at the DAE using whatever information the DAE releases, and by drawing parallels from foreign experience. In the present context of sky-rocketing demand for electric power, even before nuclear power is accepted as unsafe and expensive, the question of what other alternatives are feasible will undoubtedly be raised by the DAE and others.
This is a question that must be examined in another forum by the representative public, non-governmental bodies which would do well to take an overview and prepare an energy management blueprint to cover at least three decades, as that is the expected life of petroleum.
As far as nuclear power is concerned, it is vital that all issues are made the subject of free and frank public debate, especially because of the nexus between nuclear power and nuclear weapons. Every NPP should be discussed at the planning stage with (a) the local people, (b) the people who will be physically displaced, and (c) members of the public who are educated on the hazards of NPPs and their ill-effects.
The government should create a credible, transparent mechanism to initiate this process. Our distinguished Members of Parliament should consider (a) freezing all nuclear projects which are in the planning/construction stage, until the affected public is satisfied; (b) formation of a non-official watchdog Committee vested with investigative powers to oversee the DAE; and (c) reviewing our FBR programme.
In the national interest it is required to determine what is right and what is wrong, and not who is right or wrong. Honesty of purpose and faith in the ultimate supremacy of Truth (satyameva jayate) should guide all concerned in the troubled area of nuclear management.
Major General S.G. Vombatkere, VSM, retired in 1996 as Additional DG, Discipline and Vigilance in Army HQ AG’s Branch. He holds a PhD degree in Structural Dynamics from IIT, Madras. He is Adjunct Associate Professor of the University of Iowa, USA, in international studies. With over 370 published papers in national and international journals and seminars, his current area of interest is strategic and development-related issues.