Major traffic disruption was expected across parts of West Cumbria today as hundreds of Sellafield workers go on strike.

The action is being taken by 388 health physics monitors and some plan to picket gates at the nuclear site during parts of the 24-hour strike.

The long-standing dispute centres on the criteria of a pay rise awarded to the monitors negotiated in January last year.

The GMB union argues that all monitors should benefit from the new rate, while Sellafield Ltd says it should be awarded on merit.

The strike was going ahead despite Sellafield Ltd’s management writing to the GMB union, which represents the workers, urging members not to take the action and to remind them of their “obligation to the taxpayer”.

The letter says the strike “will impact on the entire workforce”, adding: “Every single pound lost through a lack of production or downtime on the job is a pound more of scope that has to be deferred or delayed.” 

The GMB has been in talks with site bosses for a number of years.

Matters have reached a head, the union says, after all parties thought that an agreement had been reached to settle the pay issues, only for talks to break down.

More than 83 per cent of the monitors took part in a ballot for industrial action on July 6 and almost 98 per cent voted in support of action. 

The GMB says that minimum staffing levels, understood to be 17 monitors plus apprentices not involved in the action, will be maintained throughout the strike.

Chris Jukes, GMB senior organiser, said: “It is a crying shame that we have reached this position and there is huge frustration at the complete inertia that exists within the Sellafield culture and the lack of willingness by management to negotiate openly, transparently and with a view to the future.

“We are open to discussions but Sellafield’s management are not. They pulled the drawbridge up on talks months ago.

"In my experience, I have never known such an overwhelming response to a ballot.” 

Sellafield Ltd said: “The dispute centres on a fundamental difference of understanding of an agreement by the company to reward a number of monitors who display particular skills and behaviours.

"The principle that some of those individuals are entitled to further reward is not in contention.

“Our position is absolutely clear – the principle of offering any level of payment is to further reward those whose work merits further reward.”