Radiation tolerant rapid criticality monitoring (REACTION)

In March 2011 a magnitude-9.0 earthquake struck in the Pacific Ocean off the northeast coast of Japan's Honshu island. Named the Great East Japan Earthquake by the Japanese government, it triggered a massive tsunami that flooded more than 200 square miles of coastal land. This devastating disaster caused a series of catastrophic failures resulting in the meltdown of the Fukushima Daiichi Nuclear Power Plant (NPP) and initiated a nuclear emergency. Reactor meltdown occurs when the cooling systems used to maintain and control the temperature of the nuclear fuel fails. The fuel then heats up uncontrollably and breaches the containment vessel or creates enough pressure to cause an explosion. Reactor meltdown occurred at all three reactors at Fukushima, resulting in fuel debris collecting at the base of the reactors.

Criticality is the condition where a nuclear fission reactor becomes self-sustaining. Unintentional criticality of a stricken reactor, i.e. recriticality, of the fuel debris is a major concern for the decommissioning members of the Fukushima Daiichi NPP. Despite the unlikelihood of recriticality, the possibility of it occurring cannot be discounted completely if a series of conditions were to occur simultaneously. The radiation produced by recriticality cannot pass through the concrete walls surrounding the reactor, which is beneficial for containment of immediate risk, but problematic for determining via standoff monitoring if recriticality has occurred until it is too late to take remedial action. Conversely, the radiation inside the reactor, amongst other extremes, is so intense that it presents another challenge as it can easily damage electronics and saturate radiation detectors.

This project aims to develop and deploy a ruggedised, radiation-tolerant sensor system capable of real-time detection of subtle changes in the highly radioactive environment inside the stricken reactors to rapidly detect recriticality should it occur. Such technology is also applicable to the UK's nuclear decommissioning challenges and world leading research in fusion energy.

The environmental and societal impacts of generating nuclear energy cannot be overstated, whilst the nuclear industry has received national and international media coverage for many years, especially for waste disposal. Nuclear decommissioning has been estimated to cost the UK taxpayer between £90bn and £200bn over the next 100 years, generate an extensive inventory of environmentally harmful waste to be dispose of, and potentially pose a high risk to human health and safety. Furthermore, investment in building new nuclear infrastructure before 2030 is estimated at £60bn and the cost of building and operating a geological disposal facility is around £12bn. Internationally, the corresponding figures are huge, with the global nuclear decommissioning cost estimated at £1tn.

Translating the 'radiation tolerant rapid criticality monitoring' aims of this project into industry would however dramatically enhance our knowledge of nuclear environments, leading to accelerated decommissioning, decreased risk to human health and safety, reduction in the detrimental environmental effect by enabling waste segregation, and significantly reducing costs to the UK taxpayer. This represents enormous benefits to society in the UK and internationally. The project will also have an impact on the research and development in academia, end-user industry of new nuclear fission approaches, and a greater understanding of the fusion reactor environment leading to accelerated introduction of safer more efficient low-carbon energy supplies for the benefit of society.