Please go through the Hyde Act related to US-India Nuclear agreement, specifically clauses 103 – b – 4 and 104-c-2-G.
Clause 103 deals with the US policy goals of the act.
Clause 103-b-4 states "Secure India’s full and active participation in United States efforts to dissuade, isolate, and, if necessary, Sanction and contain Iran for its efforts to acquire weapons of mass destruction, including a nuclear weapons capability and the capability to enrich uranium or reprocess nuclear fuel, and the means to deliver weapons of mass destruction."
The US Presidents will have to certify every 180 days to the US Congress among other things "A description and assessment of the specific measures that India has taken to fully and actively participate in United States and international efforts to dissuade, isolate, and, if necessary, sanction and contain Iran for its efforts to acquire weapons of mass destruction, including a nuclear weapons capability and the capability to enrich uranium or reprocess nuclear fuel and the means to deliver weapons of mass destruction"
As per the clause 106 the US president cannot give the required Waiver under clause 123 of US Atomic Energy Act (required for operating the 123 agreement) if the President determines that India has detonated a nuclear explosive device after the date of the enactment of this title (December 2006).
In short, this agreement would be nullified if we test in future. So all the nuclear power plants
