More than 150 pieces of a former pipeline from the Sellafield nuclear reprocessing plant in Cumbria, have turned up on beaches as far afield as the Isle of Man.
Underwater pipes from the Sellafield complex are being dismantled
An inquiry has begun into the incident, which Sellafield operator British Nuclear Fuels Limited (BNFL) says poses no radiation threat to the public.
Similar pieces of the plastic piping have been found on beaches in West Cumbria.
The discovery comes after underwater engineering work at Sellafield to remove one of the oldest parts of the complex.
Divers cut up the last 320 metres of redundant discharge pipeline at the plant; the bulk of the waste pipe was taken away on barges.
But some sections were being stored in undersea baskets, known as stillages.
Bad weather in November is thought to have set some lengths of pipe free.
An initial investigation suggested just 20 pieces of pipe had escaped, but almost 170 have been found so far, including four on the Isle of Man.
The BNFL said the pipes were only used for surface water drainage.
However, all other work on the project has been suspended while the few pieces of pipeline still unaccounted for are found.
The company spokesman said it deeply regretted the incident, and the board of inquiry will find out what went wrong.
When BNFL got permission in the late 1980s to replace the sea-line at Sellafield, one of the conditions was that it also had to remove the disused pipe.