To most of us nuclear physics is a mystery. But the part concrete has played in the development of nuclear power stations is no mystery, nor are the construction techniques beyond the scope of any contractor. Concrete is the only practical material for a large permanent shield against the dangers of radiation. It also offers the advantages of being inexpensive, easy to build with, structurally self-supporting, virtually indestructible, and devoid of maintenance costs. The largest contractor for nuclear power work in Britain is Taylor Woodrow Construction Ltd., of Southhall, Middlesex. This organization has just completed the civil engineering work for the Hinkley Point station on the Bristol Channel and is now breaking ground for another 5 year job at Sizewell in Suffolk. A study of the Hinkley Point project shows the extent to which concrete is used for a nuclear power station. The Hinkley Point concrete reactor structures comprises primarily a main biological shield 100 feet high, in the form of a 12 sided polygon, with secondary shielding walls surrounding it. Each reactor is also founded on a concrete raft, 120 feet by 150 feet, and around 11 feet deep, heavily reinforced in both directions. The concrete in all the shielding walls and roof slab has an average density, when completely dry, of not less then 140 pounds per cubic foot. Other components besides the reactor were made of concrete. A reactor needs a thermal lining, or a surface to take the first shock of the high temperatures generated, and behind which the primary cooling medium can circulate. Solid steel panels, welded together, have proved excessively expensive, so at Hinkley Point this thermal shield is built up of concrete panels precast at the site. Many subsidiary structures of reinforced concrete are needed at a nuclear power station. The turbine hall, where the electricity is generated, requires a sizable quantity of concrete. At Hinkley Point about 35,000 cubic yards of concrete were placed for the hall and related culvert system.