The energy ministry admitted in a statement it will need private partners to conclude construction of the nuclear plant in Rio de Janeiro state.
The facility will initially operate at 60kV and the project includes associated transmission lines.
The connection will allow a diesel-fired plant to be shut down.
Light won the tender to supply ONS offices in four cities.
The proposed legislation relates to requirements and procedures for the exemption of value added tax and import tariffs for equipment.
A major uncertainty concerns electric power firm Eletrobras' privatization process.
Colombia's public services regulator Superservicios last month published final terms and conditions for potential investors ahead of a planned February 2019 auction.