It is forbidden to sell nuclear warheads under NPT. It clearly qualifies as a nuclear device.
There is no ban on nuclear material so long it is for civilian use and preferably transferred under IAEA safeguards and oversight.
It is NOT forbidden to sell nuclear powered submarines. Only its nuclear payload i.e. nuclear capable SLBM and SLCM would be barred from sell, and that too due to international norms. MTCR is an informal agreement (not formally binding). Essentially, its just the nuclear warheads for SLCM & SLBM that states are formally not allowed to sell. The fuel for nuclear submarine is a big grey area. If nuclear submarines were ever banned, USSR/Russia would never have been able to even lease it to India. The reason states don't sell nuclear submarines are due to the; (1). political implications, (2). technological implications, and (3). operational implications: most possessor states usually only produce and operate minimum required number of nuclear submarines because of their high cost. Thus, they can seldom afford to divert them away from national operational requirements.
China has scarcity of nuclear powered submarines and would not be willing to handover its new boats to anyone, though it may be willing to accommodate PN personal onboard its subs for training purpose. The Type-092 - PLAN's first nuclear submarine - has a questionable capability, is underpowered, and is a health hazard. PLAN might have even secretly retired it by now. If PN wants a nuclear submarine it would have to build one indigenously with or without Chinese assistance. The question is whether we actually need one? PN seeks littoral deterrence, for which AIP equipped conventional submarines with few Vertical Launch Systems (VLS) could suffice.
Of course we can opt to buy if we want to retain the Lease units
, how slow and lame u indians are......
