Sannah H P van Balen
NEF CDT Student
Department of Engineering
University of Cambridge
Contact: shpv2@cam.ac.uk
Sponsor: EPSRC and Nuclear Waste Services
Rethinking nuclear risks: reasonableness in low-level radiation protection
Radiation is impossible to sense; it doesn’t have a smell, a taste, a sound, a texture, or a characterising appearance. Nevertheless, high-level radiation can damage our bodies and result in serious health effects (e.g. Acute Radiation Sickness). In cases of low-level radiation exposure, the health risks are more difficult to pin down. These primarily actualise as an increased probability of developing cancer (known as stochastic effects). Combining the uncertainty in health effects with the intangibility of radiation makes risks particularly difficult to assess and prone to (mis)perceptions that can impact risk management strategies.
In radiological protection, the linear non-threshold (LNT) model is used to infer stochastic risk from exposures at low dose and low dose rate, and protect people from any potential harmful health effects. Based on the prudent assumption that there is no safe dose of radiation, the LNT risk model is closely linked to the Optimisation Principle – this principle states that exposures to radiation must be kept As Low As Reasonably Achievable (ALARA). In nuclear safety cases, facilities must demonstrate that radiation protection measures are incorporated into their engineering designs that minimise exposures to workers and the public to a “reasonable” amount. But, when confronted with low-level radiation, how does one determine what constitutes a reasonable effort to spend on an undemonstrated risk?
Currently, safety cases tend to demonstrate their adherence to ALARA through dose minimisation rather than optimisation. By taking reasonability out of the equation, the nuclear industry appears to be taking an “as safe as possible” approach in the hope of gaining regulatory and public acceptance of its technology and/or facility. Not only has this sparked concern about the cost of mitigation efforts in the form of over-engineering, but also that such measures feed a potentially excessive societal fear of radiation.
Considering the amount spent on preventing a risk from actualising, one may rationally conclude the risk associated to nuclear is unacceptable by nature. This research explores potential drivers for a dose minimisation strategy and attempts to quantify the resulting cost of over-protection. Subsequently, it explores how reasonability may be brought back into radiation risk management and nuclear safety cases through increased stakeholder involvement.
Achievements
Winner Cambridge-McKinsey Risk Prize, Cambridge Centre for Risk Studies, essay title: Rethinking low-level radiation risks: the Linear Non-Threshold (LNT) Model for radiation and its scientific validity.
NEA Rising Star Programme, Nuclear Energy Agency and MIT, winner of poster presentation.
Highlights
Due to the complexity of this research, I have had the opportunity to connect with a variety of relevant authorities and researchers. Engaging with the Nuclear Energy Agency (NEA), the International Commission on Radiological Protection (ICRP), and the research group on Public Health at Nagasaki University are definite highlights. At the same time, exploring different schools of thought on risk and ethics within the Cambridge University community has brought new ideas to the topic of nuclear risks.
Future plans
I believe this topic touches upon very fundamental questions about society and how we address the multitude of risks, both natural and technological. I hope that the outcomes of my research will lead to further research projects that aim to develop governance structures for risks whose consequences are uncertain or ambiguous, and could benefit from a societal perspective.