A nuclear plant in Cumbria has been fined £2m after breaching regulations which led to a radioactive leak.
The leak occurred at the Thorp complex at Sellafield
Acid containing 20 tonnes of uranium and 160kg (353lb) of plutonium escaped from a pipe and was found in a sealed cell at Sellafield in April 2005.
Plant operator British Nuclear Group Sellafield (BNGSL) admitted responsibility and has been fined by the Nuclear Decommissioning Authority.
BNGSL said it "deeply regretted" the incident and was committed to safety.
A spokeswoman said: "British Nuclear Group is totally committed to achieving the highest standards for health and safety, security and the protection of the environment.
"We deeply regret that this incident happened."
No one was hurt and no radioactive material escaped into the atmosphere after the leak at the Thermal Oxide Reprocessing Plant (Thorp) part of the site.
But the spillage, discovered in April 2005, may have gone unnoticed for eight months.
In June, at a hearing at Whitehaven Magistrates' Court, BNGSL pleaded guilty to three counts of breaching conditions attached to the Sellafield site licence, which was granted under the Nuclear Installations Act 1965.
The Health and Safety Executive (HSE) brought the prosecution, arguing the firm failed to ensure safety systems were in good working order and that radioactive material was effectively contained.
Work at the Thorp complex has been halted since the incident.
In its report the NDA said: "We have made it clear of our absolute commitment to the highest standards for health and safety, security and protection of the environment."