BAS PEASE was a distinguished advocate of the peaceful application of nuclear power for the generation of electricity. A first-class physicist, he spent his working life with the United Kingdom Atomic Energy Authority (UKAEA). If nuclear fusion proves to be the safe and clean source of power which its champions predict, he will be numbered among those who contributed most notably to its development.

His major research involved the use of X-ray crystallography to study the positions of hydrogen atoms in crystals and the structure of solids. The purpose of the research was to understand how materials behave when subject to the extremely intense radiation in the core of a nuclear reactor. Pease’s particular interest was radiation damage in graphite, uranium and the materials used in the construction of nuclear reactors.

Rendel Sebastian Pease, known by all as Bas, was born at Girton, Cambridge. His father was Michael Pease, a classical geneticist at Cambridge University; his mother was Helen Bowen (née Wedgewood).

His family was a very political one, committed to Fabian socialism. His paternal grandfather, Edward Pease, was co-founder of the Fabian Society and, hence, of the Labour Party. Pease’s father also contributed much to the Fabian Society, and he himself continued the family tradition of commitment to the Fabians.

Until he was about 11 years old, Pease was taught at home, mainly by his mother; he then went to Bedales School, Petersfield, Hampshire. When he finished his schooling, the Second World War had begun. He went to Trinity College, Cambridge, to read physics on a wartime degree course. In December 1942, before he had finished his degree, he was directed to the Ministry of Defence to join the RAF Bomber Command’s Operational Research Service.

Working as a scientific officer in the headquarters of Bomber Command in the Chiltern hills, north of High Wycombe, he was one of a team of about 30 civilian scientists, analysing bombing operations, devising means of reducing losses and of increasing the effectiveness of bombing. He specialised in radar systems designed to navigate aircraft to their targets.

In 1946 he was released from Bomber Command and returned to Cambridge to finish his degree. Graduating in 1947, he started his career with the UKAEA as a scientific officer at the Atomic Energy Research Establishment at Harwell, Oxfordshire, working in the X-ray analysis section of the general physics division.

Pease worked at Harwell for 14 years, making important contributions to nuclear metallurgy. In 1955, he published, with George Kinchin, a key scientific paper on the mechanism of damage to solids by radiation in a reactor core, providing a crucial theoretical model of how heavy fast particles and gamma (electromagnetic) radiation behave when they pass through a sold. The paper is a classic in its field.

In 1961 Pease was appointed division head at Culham Laboratory for Plasma Physics and Nuclear Fusion. In 1967, he became the assistant director of the UKAEA Research Group; between 1968 and 1981 he was the director of the Culham Laboratory; and in 1981 he became the programme director for fusion at Culham, a post he held until he retired in 1987. The Culham laboratory, part of the Culham Science Centre, was set up in 1960 on a former airfield near Didcot, Oxfordshire. The UK Engineering and Physical Sciences Research Council and Euratom jointly fund the centre which now employs a staff of 1,600 on its 180-acre site.

Culham’s ambition is to develop a nuclear fusion reactor to generate electricity. Advocates of fusion power, as Pease was, argue that, if successfully developed, it offers the potential of an almost limitless source of energy. But very formidable scientific and engineering problems must first be solved.

A fusion reactor relies on the fusion (the joining together) of light nuclei, such as the nuclei of hydrogen atoms, to produce energy. This energy is used to produce steam from water to turn turbines to generate electricity. Today’s operating nuclear-power reactors rely on the nuclear fission (splitting apart) of heavy nuclei, such as nuclei of the isotope uranium-235, rather than on nuclear fusion.

Fusion in a fusion reactor would be similar to that which powers the sun and other stars. In a fusion reactor, a combination of isotopes of hydrogen, deuterium and tritium would be heated to very high temperatures (100 million degrees Celsius), similar to the temperatures in the sun, and confined for at least a second. Culham scientists hope to achieve these conditions by magnetic confinement in a tokamak, a Russian word for a torus-shaped magnetic chamber — a sort of doughnut-shaped magnetic bottle. In the torus, the hot gas would be held well away for the cold walls of the container, and the gas would be heated by passing an electric current through it.

The original British large-scale experimental fusion device, called Zeta (zero energy toroidal assembly), dates back to the 1940s and 1950s. Zeta, built in a hangar at Harwell, showed that the toroidal configuration could produce confinement lasting many milliseconds. The Zeta project was led by Pease.