The world's oldest nuclear reactor is due to shut down on Monday after generating electricity for almost 50 years.
Calder Hall in Cumbria was opened by the Queen in 1956
Calder Hall in Cumbria was opened in 1956 using Magnox technology.
It was cutting edge technology at the time, but by today's standards its 196 megawatt capacity is considered small.
British Nuclear Fuels Limited (BNFL), which operates the plant on the Sellafield site, blames the closure on the depressed price for electricity, along with the relatively high overheads of such a small plant.
About 150 workers will take part in a ceremony marking the closure, while environmental protesters are expected to gather at the gates.
The site, which is closing three years early, was named last year along with Chaplecross power station in Scotland, as being obsolete.
BNFL chief executive Norman Askew said: "This is a tough but necessary commercial decision.
"I have always said that we would continue to run these pioneering workhouses of the nuclear industry while they remain safe and economic.
"They are still safe but the electricity prices have fallen significantly and to a level that makes them uneconomic.
"We do not see this fall in price recovering in the next few years and thus we can no longer justify running the plants."
Calder Hall has four giant magnox reactors, which were scheduled to operate until at least 2006.
A Friends of the Earth spokesman said: "Nuclear power has proved itself time and time again as uneconomic, unsafe, unpopular and unnecessary."