Since its inception people have asked the question: is nuclear power safe? During the forty years that commercial power plants have operated worldwide, there have been about eight dozen major accidents, three of which -Windscale (1957), Chernobyl (1986) and Fukushima (2011) — were especially serious. At Chernobyl, 31 worker deaths were recorded immediately and it is estimated that there were up to 5900 more in the months and years that followed as a result of radioactivity from the fire in the reactor across Europe. Reactor designs since the accident at Three Mile Island (1979) have been upgraded with new, multilayered and redundant safety systems, developed specifically to avoid such errors. Chernobyl, for example, was built without any containment structure, according to a design that would have been instantly condemned anywhere in the West. Both incidents, however, inspired many changes, leading the IAEA to establish a global network for peer review of sites, designs, operating procedures and creating a collection of ‘‘best industry practices’’. Plant design now stresses passive safety; the reactor shuts down automatically in case of any irregularity.

Nonetheless such guidance proved ineffective in preventing the disaster at Fukushima, where worse case scenarios were discounted in the disaster man­agement plans of the site and as a result sea defences were woefully inadequate. As a result, this led to back up diesel power systems failing due to the sea defences being overwhelmed with the wave from the tsunami and with the final battery power running out, a number of the reactors were left without coolant, leading to a partial meltdown of reactors on the site. As a result Japan has officially admitted the Fukushima nuclear disaster is as bad as Chernobyl and has upgraded the incident to the worst case level 7.

Whilst we have seen the development of a much stronger safety culture within the industry over the last 20 years, nuclear power plants have the dis­advantage of being so complex that almost every reactor has experienced some sort of incident or failure over its history, and even if the risk of a true melt­down is low, the impact of such an accident would be very large.125 Nonetheless the safety record of existing nuclear reactors has improved over time as their margins of error have improved and safety regulations have been upgraded. The industry has incorporated research findings on human factors and safety

xlviA problem discussed by the Committee on Climate Change Science and Technology Integration 2009.

culture through groups and organizations such as the IAEA and the World Nuclear Association of Nuclear Operators created after the Chernobyl accident in 1986.126

A scenario envisaged by the authors of the MIT study was an optimistic three-fold increase in the world nuclear fleet capacity by 2050. They concluded, after undertaking a probabalistic risk assessment (PRA), that one would expect four core damage accidents during this time (they based their analysis on current estimates of core damage to occur once in every 10 000 reactor years). They concluded that this was an unacceptably high number — it should be 1 or less, which is the current expected safety level.127 They concluded that a core damage frequency of 1 in 100000 reactor years is a desirable goal, which is a ten-fold reduction from current levels. The designers of the new light water reactors currently being built argue that they already achieve these goals through advanced safety measures and greater use of passive safety mechan — isms. xlv11 It is beholden on regulators to assess these claims to enhanced safety of the latest generation of LWRs during the (pre)licensing phase of reactors.

We do not believe there is a nuclear plant design that is totally risk free. This is due to technical and workforce issues. Safe operation requires effective regulation, management who is committed to safety and a skilled work force. The restruc­turing of electricity sectors around the world has motivated some operators to place profits before safety. Undue solicitude for profits of the licensee has played a large role in explaining the mishaps that have occurred at nuclear power plants. Nuclear power is least safe in environments where complacency and pressure to maximize profits are the greatest. It is of continuing concern as to ‘‘whether nuclear reactor safety goals are compatible with the transition to competitive electricity markets’’.129 Owners and managers of nuclear plants respond that it is econom­ically beneficial to ensure high levels of safety, given the enormous financial costs of accidents. However, well funded regulatory agencies are vital to ensuring plant operators do not neglect safety inspections for continuous plant operation.

However at Fukushima it would appear that a number of regulatory failures and cost cutting exercises by the owner Tokyo Electric Power Company (TEPCO) contributed to the severity of the disaster. As far back as July 2000, ‘‘four ominous unexpected shutdowns occurred, some releasing unacceptable radiation levels, in the plants run by Tokyo Electric Power Company (TEPCO), Japan’s largest uti­lity. In 2001, a whistle-blower triggered disclosures of falsified tests at some of the company’s seventeen plants, and the government forced TEPCO to close some plants’’.172 Moreover, ‘‘in 2002, the company predicted that all of its seventeen plants might have to be shut down for inspection and repairs, because of falsified inspections and concealment of faults found in inspections that the government ordered; some of the faults were potentially catastrophic” (ibid). As a result a top

xlvn‘‘Additional gains may come with the introduction of High-Temperature Gas Reactors (HTGRs). In principle the HTGR may be superior to the LWR in its ability to retain fission products in a loss-of-coolant accident, because of fuel form and because core temperatures can be kept sufficiently low due to low power density design and high heat capacity of the core, if RD&D validates this feature’’.128 The HTGR also has an advantage compared to light water reactors in terms of proliferation resistance.

company official was charged with giving specific orders to hide large cracks in the ‘‘shrouds,’’ or steel casings around the reactor core, in two of the thirteen reactors at which false inspection reports had been filed. According to documents from Tokyo Electric Power (Tepco), the company “repeatedly missed safety checks over a 10-year period up to two weeks before the 11 March disaster, and allowed ura­nium fuel rods to pile up inside the 40-year-old facility’’.173 This exposes the pro­blem of cost cutting initiated by the chief executive, Masataka Shimizu, in that the company opted to save money by storing the spent fuel on site rather than invest in safer storage options.