Beaches near the Sellafield plant in Cumbria are to be monitored for a year for radioactive material.
Increased monitoring has been taking place in the area after a particle of radioactive material was found at Braystones beach in 2003.
British Nuclear Group (BNG), which operates the plant, said the next phase of testing would be at beaches between Drigg and St Bees.
The extra monitoring is a requirement set by the Environment Agency.
The work is expected to be completed by March next year.
A spokeswoman for Sellafield said: "A particle of contamination was found by our investigators in 2003 and extra monitoring is on-going.
"We just want people in the affected areas to be aware there will be increased activity with vehicles mounted with monitoring equipment being used in the tests."
A spokesman for BNG said it would attend parish council meetings in April and May to ensure councillors and members of the public were aware of the programme and to discuss any concerns.
A spokesman for the Environment Agency said Sellafield had recently trialled new, improved monitoring equipment to carry out tests.