It's 50 years since the start of operations at the Magnox reprocessing plant at Sellafield in Cumbria.
The plant opened in 1964 and to date, it has reprocessed 52 thousand tonnes of radioactive waste from Magnox power stations in the UK.
Thousands of people have worked there, it now employs around 400.
To mark the facility's 50th birthday, 50 former workers were invited along, including one engineer who was there on the very first day it opened.
Our cameras were allowed in for the first time in half a century. Matthew Taylor reports.
More top news
What has the weekend weather got in store for the Border region?
Do you know what's been happening in Cumbria and the south of Scotland over the past seven days? Test yourself in our weekly news quiz.
Two small creatures from thousands of miles away could create big problems for Cumbria's rivers.