About 400 contract workers at Aberthaw Power Station in the Vale of Glamorgan, who walked out for a second day over safety fears, may return on Thursday.
24-hour medical cover will now be available at Aberthaw
They and hundreds more first walked out on Tuesday over on-site medical care after the death of a man on Sunday.
Another 400 workers - who are building a new plant - met on Wednesday and agreed to a company offer of 24-hour medical cover. They are back at work.
A union said it was believed news of this offer did not reach all workers.
Another section of the workforce had held a separate meeting on a different part of the site, and the Unite union blamed a "breakdown in communication" for full details of the company's offer not getting through to them.
These workers are involved in the routine maintenance of the existing power station.
However npower, which owns the power station, said these workers were expected to return on Thursday after discussing the new arrangements with their employers.
Npower said that about 400 workers for AMEC, the lead contractor for the construction of the flue gas desulphurisation project, returned to work on Wednesday after the company arranged for a registered medical nurse to be on site as an interim measure.
A paramedic with fully equipped vehicle will be on site from Thursday and ambulance facilities would be arranged over the next few days, said npower.
Unions said the industrial action had not affected the operation of the generating side of the plant because none of these workers, employed by npower, were involved.
The walk out followed an incident on Sunday, where a 49-year-old man who worked in the sea wall intake area as part of the flue gas desulphurisation project, died after an accident.
The Welsh Ambulance Service said the man had a heart attack. He later died at the University Hospital of Wales, Cardiff.
Aberthaw is a coal-fired power station.
The site is owned by npower, but the workers who walked out are understood to have been working for contractors AMEC and Alstom.