2.1 Production reactors

The first large-scale reactors were built for the purpose of producing plutonium for nuclear weapons. Such reactors are generally referred to as production reactors.

The first US production reactor was built at Oak Ridge, Tennessee in 1943, based on the Chicago Pile. A core made of graphite blocks had horizontal channels containing the fuel, which was in the form of cylindrical slugs of natural uranium in an aluminium casing (known as cladding). The channels were cooled by air blown through them.

Eventually nine production reactors were built along the bank of the Columbia River, near the town of Richland, Washington. The Hanford reactors also used natural uranium clad in aluminium stacked in horizontal channels in a graphite core. The heat they generated required high-efficiency cooling, which was achieved by pumping water out of the river directly through the pile and back into the river.

The UK s nuclear programme also began with the impetus to produce nuclear material for military purposes. It began with production reactors, which were built at Windscale in northwest England, on the site of a disused ordnance factory, and later developed into a power programme. The following descriptions of the UK s early reactors are based on Walt Patterson s UK nuclear history Going Critical.

As in the US reactors, the first two production reactors used natural uranium clad in aluminium as fuel stacked in horizontal channels in a graphite core, and these were known as Windscale Piles 1 and 2. The cores of...