The Minister for the Environment, Mr Cullen, is to express concern over the safety implications of an ongoing strike by workers at Sellafield when he meets with his British counterpart, Ms Margaret Beckett, today.
Strike action by hundreds of employees has forced the reprocessing plant to close three times in the last month, while a further work stoppage is planned later this week.
Both unions and management have insisted the industrial action has not compromised safety at the complex in Cumbria.
Unions accuse British Nuclear Fuels Limited (BNFL) of reneging on an agreement to close a pay gap between manual workers and white collar workers, a charge rejected by the firm.
BNFL has offered arbitration talks over the shift pay row. Unions have said they may postpone further industrial action if members agree to the offer.
It is also expected the circumstances surrounding an accident last week, in which sections of broken waste pipes from the plant were found washed up on local beaches, will be discussed.
British authorities contacted the Department of the Environment about the incident last week.
It said chunks of the pipes, which were being removed as part of a decommissioning process at the plant, were not radioactive.
It also emerged yesterday that a study commissioned by the British government found that Sellafield is a source of plutonium contamination.
The study found plutonium levels in children's teeth were twice as high for those living close to the plant compared to children living 140 miles away.
Britain's public health minister, Ms Melanie Johnson, said the levels were so minute there was no risk to public health.
