Spotlight: Dr Donald Skea, Nuclear Criticality Safety Manager (retired)


Tell us a fun fact about yourself.


I have always been an active person – football, badminton, hillwalking and swimming. A few years ago I took up Scottish Country Dancing. It is a fun social activity requiring good balance and agility.

Tell us about your career journey so far.


I spent most of my career working for the UK Atomic Energy Authority / Dounreay Site Restoration Ltd.


The Dounreay nuclear site is in a remote area near the town of Thurso and near the northernmost point of the Scottish mainland. It was a big decision to go to such a remote place, having been brought up, and studied, in the central belt of Scotland. I felt very unsure that it was a good decision to go there. However, I knew that the nuclear power industry was highly technical, and scientific / technical work was my main interest.


In my time at Dounreay I had a number of different roles – chemistry laboratory analyst, instrumental analytical techniques development and management, project management, environmental management, and criticality safety management. Criticality safety was the most interesting and challenging role. Since retiring I have become a private tutor in physics, maths and chemistry. My background gave me the knowledge to teach these subjects.

What was your favourite subject in school and why?


At school my favourite subjects were physics, maths and chemistry. I would find it difficult to pick out one above the others. I found maths fascinating because exact solutions are possible, and it helped to develop problem solving and analytical skills


What subjects/qualifications/skills are useful for your role?


A technical background and a professional qualification are very useful for this role. It is necessary to have an understanding of the manufacture and processing of nuclear fuel. There is some maths involved in the calculation of safe amounts of fissile material in different geometries. As Criticality Safety Manager I had a small team to maintain the safety management system and perform criticality safety audits. Personal skills in dealing with people are important.

What is your favourite thing about your job?


My time working in the nuclear power industry gave me much variety in terms of the different roles I played over the years. In criticality safety management I was given the remit to merge criticality with the safety system covering other types of hazards. This gave me the opportunity to innovate to some extent.


I modernised the format of criticality hazard analysis documentation, and the approval route for the documentation. On the technical side, I became familiar with neutron modelling software and the established data on critical amounts of fissile material.


What is a normal day in your role like?


A typical day would be some, or all, of the following activities – review of criticality hazard analysis documentation, review of plant safety audits, presentations at safety approval bodies, meetings on safety implementation with plant managers, meetings and discussion with my technical team.


And what does your job title mean?


A nuclear criticality is the process by which a nuclear reactor generates heat, which ultimately leads to the generation of electricity. A reactor criticality is carefully controlled. A nuclear criticality outside a reactor is uncontrolled, very dangerous, and very unwelcome. It was my job to ensure that criticalities never happen outside a reactor, for example during fuel handling, fuel manufacture, fuel recovery or fuel analysis.