A report from the local council warns that the construction workforce will reach its peak in 2017 – and up to 70% of builders will need accommodation while working on the plant.
The influx will stretch housing resources to the limit and councillors fear landlords will prefer more lucrative private tenants to locals on housing benefit.
The report said construction workers will need more than 50% of the island’s accommodation currently let to people dependent on state help.
Council revenue and benefits manager Geraint Jones said: “If the Wylfa B development goes ahead, some private sector landlords may decide to pull out of letting to housing benefit claimants altogether.
“Due to the lack of social housing available as an alternative, many claimants could find themselves homeless.”