Daniel Garodnick and his colleagues filed an amicus brief in support of Assemblyman Richard Brodsky's appeal to the United States Court of Appeals for the Second Circuit.
They believe the nuclear facility, which sits 35 miles north of Midtown Manhattan, should not have been granted several safety exemptions.
One exemption mandates that the wrapping that protects cables that provide power to safe-shutdown mechanism be resistant to fire for 24 minutes. But the standard is one hour.
Garodnick on Wednesday called the exemption "a danger to millions of New Yorkers."
A spokeswoman for the Nuclear Regulatory Commission, which approved the exemption, said the facility is safe.