Controversies / Strengths and Weaknesses
Transparency, a double-edged sword
Transparency requires common understanding – by officials and by the public – of terms used by the nuclear community. For example: a reactor is not the same thing as an entire nuclear power plant. An incident in the non-nuclear part of a nuclear site does not necessarily mean that nuclear safety is at risk.
Historically, the nuclear industry started for military purposes, i.e. the A-bomb.
Army people being, by definition and in some cases by necessity, opposed to transparency, this led to a « culture of secrecy » that prevailed for years. The TMI accident, and then the Chernobyl accident induced strong reactions from the public asking for transparency about what happened at nuclear installations.
Today, independent nuclear regulatory authorities publish, on a regular basis, results of their inspection and regulation of nuclear reactors and related equipment and installations.
But transparency is a double-edged sword. The creation of the INES scale for nuclear events led to the publication by nuclear regulatory authorities of all “events” occurring in nuclear installations. But, as indicated in the section “from incidents to accidents”,
because the scale does not take into account events that are not relevant to the nuclear part of the installation – that is, to nuclear or radiation safety -, some incidents classified as “minor” by nuclear authorities can impact nuclear safety.
In any case, an increase of declared events during a year does not necessarily mean that safety has been put at risk during that specific year – it may mean simply that the operator is disclosing more information about his operations, or that regulations have been tightened.
Standards of radiological protection
As noted in the section “key concepts”, the average person receives 3 mSv yearlyfrom background (“natural”) radiation.
In addition to this background radiation, the International Commission on Radiological Protection recommends limiting occupational radiation exposure to 50 mSv (5 rem) per year, and 100 mSv (10 rem) over 5 years, or an average of 20 mSv/y. For the public, the ICRP recommends a dose limit of 1mSv/y, or 5 mSv over 5 years, i.e. the annual 1 mSv limit can be exceeded under special circumstances. Individual countries, and the European Union as a whole, derive legal limits from the ICRP recommendations, which are revised periodically to take into account new information. But they can be interpreted in different ways. European Union member countries have chosen to stick to the 1mSv/y for public exposure and 20 mSv/y for occupational exposure.
Other countries have interpreted the ICRP recommendations differently, allowing workers to accumulate 50 mSv in a year – this is the case in the US.
The ICRP sets higher limits in cases involving accidental exposure: occupational radiation exposure should be limited to 100 mSv/y, but it can be up to 250 mSv/y if workers understand and accept the risk, as was the case for the workers that remained on site to cope with the accidents at the Fukushima Dai-ichi nuclear power plant.
Specific standards have been developed for specific domains of exposure (radiotherapy, nuclear waste, research reactors, etc.
All these limits are essentially normative values because they refer to averages, without taking into account individual circumstances. For example, some people may live or work in a higher radon environment than others (such as a region with granite) and people do react differently to radiation.
Despite many research projects worldwide, scientific uncertainties remain on the health effects of low radiation doses. Research conducted to date has found no cause-effect relation between low doses and illnesses, specifically cancers.
Low doses have generally been considered as those below 100 mSv/y, because that is the level where no health effects have been observed in the general population. However, the mainstream scientific community has recently agreed on a “threshold” dose of 50 mSv to take special cases into account, such as the foetus or infants.
Cancer is not the only risk from radiation doses; scientists have studied the relationship between radiation exposure and development of circulatory disease, cerebro-vascular or gastro-intestinal disorders, for example.
A group of 15 institutions in the EU set up in 2010 an association known as Multidisciplinary European Low Dose Initiative (MELODI) dedicated to low dose radiation risk research. Its research agenda is very broad, covering cancer and non-cancer diseases (including some effects of local doses up to 500 mSv, such as cataracts or cognitive dysfunction), as well as development of guidelines for short, medium and long-term exposure and health risk monitoring in case of a major nuclear accident in Europe.
Radioactive waste and environment contamination
Nuclear waste represents a challenge for future generations. But in fact, radioactive wastes have been accumulating since the discovery of radioactivity. In France, the country of Marie and Pierre Curie, many laboratories where radioactive materials were used have been abandoned, leaving behind hazards that long remained unknown. In the second part of the 20th century, mapping of those laboratories helped locate the radioactive waste inside, providing one of the most efficient measures to guarantee against accidental exposure.
However, it is not unusual to “discover” some “hot spots” left behind without adequate notice.
One of the biggest challenges at present concerning nuclear waste is the dismantling of reactors and research facilities, as well as of radiotherapy equipment or scanners.
Deep burial of highly radioactive wastes has raised new concerns, for example: how to keep the knowledge of the buried waste alive over long periods of time– hundreds of generations? Debate continues between supporters of landmarked sites and their opponents. The latter estimate that if waste is deeply buried, the chances that future civilisations will come upon it are low and even if they do, they will recognise the waste as hazardous.
Nuclear technology follows a pattern of continuous improvement. In radiotherapy, the amount of X-rays emitted today is far lower than at the beginning of radiotherapy (early 20th century). The same pattern can be found in radioactive sources used in industry.
Nuclear reactor technology is no different. At present, the nuclear industry is proposing, and even building, what is called the third generation of nuclear reactors (EPR, AP1000, AES-1200, ABWR, ESBWR), which represent improvements over the current generation but retain the same main features.
Improvements have also been made on reactors of the second generation (most of those operating in the world), while the first generation has mostly been retired.
A fourth generation of nuclear reactors is under development in several countries, which collaborate in the Generation IV International Forum (GIF). The fourth generation is supposed to be better than the third under several criteria: sustainability, economics, safety, reliability and proliferation-resistance. Of the six designs being studied in GIF, four are fast neutron reactors (or fast reactors), so called because they do not have moderators that slow down some of the neutrons in the chain reaction. Fast reactors offer much more efficient use of uranium, as well as the potential for transforming long-lived elements in used nuclear fuel into shorter-lived elements, in principle greatly facilitating nuclear waste disposal. However, they present special challenges in terms of resistance to nuclear proliferation (notably the presence of separated plutonium), for which researchers are seeking economic solutions.
Many technological improvements have been linked to reinforcement of safety measures following major accidents or generic incidents. As seen in the section “from incidents to accidents”, every incident has led to a reinforcement of safety culture in nuclear installations. Through the IAEA and the OECD Nuclear Energy Agency, among other organisations, collaboration and exchange of experience in the field of nuclear safety is a common practice.
In Europe, two organisations also share best practices and even develop common safety requirements: ENSREG (a European Union institution) and WENRA (an informal “club” of nuclear safety regulators).
Nuclear energy is one of the only activities where independent international reviews are conducted on a regular basis and/or requested by operators to validate their practices, especially in the field of safety.
The Fukushima accident led to a new way of thinking about safety. Up to that point, the probability of a nuclear accident was considered low in many countries. Nuclear facilities are designed so that earthquakes and other external events (such as flooding) will not jeopardise plant safety. The International Atomic Energy Agency (IAEA) has a Safety Guide on Seismic Risks for Nuclear Power Plants. Various systems are used in planning, including Probabilistic Seismic Hazard Assessment (PSHA), which is recommended by IAEA and widely accepted.
After the Kobe earthquake of 1995 that registered magnitude 7.2 on the Richter scale and revealed shortcomings in seismic design assumptions at the Kashiwazaki-Kariwa nuclear power plant on the west coast of Japan, the safety of nuclear facilities in Japan was reviewed along with the design guidelines for their construction. The Japanese Nuclear Safety Commission (NSC) then approved new seismic protection standards. Building and road construction standards were also thoroughly reviewed at the time. After recalculating the seismic design criteria required for a large nuclear power plant to survive near the epicentre of a large earthquake, the NSC concluded that under current guidelines, such a plant could survive a quake of magnitude 7.75. The guidelines were revised again in 2000.
Nevertheless, it was not the 2011 Tohoku earthquake that caused the problems at the Fukushima Dai-ichi nuclear plant, at least not directly. It was the force of the tsunami that was triggered by the 2011 Tohoku earthquake that led to the major accident at Fukushima (cf. “stories – accidents” section).
This unpredicted event resulted in an overhaul of nuclear safety in most countries. The EU asked European countries to set up complementary safety assessments – which became known as “stress tests” on the model of banking tests after the 2008 financial crisis – for all nuclear reactors in Europe. Even if the EU did not set in place a common procedure to do so, most member states decided to evaluate their practices in case of an unpredictable event (e.g. earthquake or flooding of an unprecedented type or level) that could affect nuclear facilities.
In France, stress test results contributed to the setup of a dedicated fast-response team (Force d’action rapide nucléaire, or FARN) with special equipment and training that could be deployed within 24 hours of an accident at any French NPP, and to the reinforcement of back-up facilities on nuclear sites and to the construction on-site of dedicated emergency buildings.
All industry fields matter
The nuclear industry is a chain in which all fields must apply best practices.
This applies all through the “nuclear fuel cycle”. The latter begins with mining and milling of uranium ore, then proceeds through solid uranium conversion to gaseous UF6 that can be fed into enrichment plants, then enrichment (in which the concentration of the fissile isotope U-235 in the gas is increased), reconversion of gaseous UF6 to solid uranium oxide that is fabricated into fuel rods, then irradiation of fabricated fuel in reactors, then dismantling of facilities, handling of radioactive waste and used nuclear fuel, and final disposal, as well as transport of all kinds of radioactive materials.
Every single field of the industry must be irreproachable as regards nuclear and radiation safety. Nevertheless, if the main concepts remain — prominently defence in depth –each part of the chain has its specific regulation.
Any event in a nuclear installation of any nature can lead to challenge the entire chain. Opponents use these arguments – i.e., safety problems that can occur at a specific part of the chain – against the nuclear industry as a whole.
Born for political purposes (defence), the nuclear industry has, from the beginning, been under political pressure.
We may recall that in Germany, in the 1960s it is the government that asked the electric utilities to develop nuclear energy against their will, as utilities were sitting on a flourishing coal industry. So a political pressure decided the choice made by utilities in Germany. This must be borne in mind when Merkel’s government decided the end of the nuclear industry in Germany after Fukushima disaster in 2011. Big utilities asked for compensation for what would eventually become stranded assets… Their claims were upheld in the courts., though some in Germany think the utilities are not entitled to compensation.
In France, the government alone decided, in the 1970s, to develop a vast nuclear power program, in response to the oil crises of 1956 and 1973 and the lack of energy resources on French soil.
The national utility, EDF, was fully owned at that time by the State, making it easier to decide on and deploy such a program.
In both cases, the involvement of the state had implication on safety/handling of the risk associated as well as on liabilities. Specific laws were set up in order to decide who will handle the risk, who will be running the safety analysis, and who will be responsible for liabilities. And these laws evolved during the lifetime of installations.
With regard to waste disposal facilities, and notably a final repository for highly active and long-lived waste, site selection is always a matter of politics.
Economic factors and market conditions can also impact industry. In the 2000s, when a nuclear “renaissance” emerged in the US in favour of new nuclear build, no one expected massive investments in shale gas. When those investments did come and paid off with big supplies of cheap gas, it put pressure on electricity prices in a competitive market… and also on the nuclear industry.
In the same way, liberalising Europe’s electricity market, combined with a massive increase on that market of power from renewables with direct market access, put pressure on the nuclear industry’s competitiveness and, in turn, led to measures, like employment of more subcontractors, that could put pressure on its safety.
In the case of Germany, the massive increase of renewables on the electricity market led to a collapse of wholesale prices.
The final blow to the Germany nuclear industry came a few days after the Fukushima accident, when Chancellor Angela Merkel — who had previously approved nuclear plant lifetime extension – reverted to the earlier policy calling for short-term phase-out of nuclear energy and the immediate shutdown of 8 older reactors. This U-turn for German policy did not take into consideration the provisions set aside by utilities to pay for decommissioning the reactors at the end of their planned operating lifetimes: the shorter the operating period, the less time for building up decommissioning funds
Soon, the nuclear industry was criticized in public debate for its lack of preparation for decommissioning, as well as lack of a national final repository for nuclear waste.
The government hurriedly set up special commissions to try to resolve the issues.
A final point: the shift to renewables led to a shift of academics and students towards renewables studies instead of nuclear-related studies. Today, nobody knows from where will come the engineers who will decommission the reactors and manage the waste tomorrow…