The explosion at the Kleen Energy Systems power plant in Connecticut, US, happened as workers purged a natural gas line.
The blast killed five people and injured 26 last week.
Local police are reportedly looking into possible criminal negligence as the cause of the blast and treating the plant as a crime scene.
Spectra Energy that delivers gas to the station has shut its facilities for gas transfer to the plant following the explosion.
The 620MW power plant, designed to be fuelled by natural gas and oil was under construction and almost 96% complete.