No. There is some evidence that a large flux of neutrinos can very slightly alter the rate of some nuclear beta decay (basically the decay which would release a

No. There is some evidence that a large flux of neutrinos can very slightly alter the rate of some nuclear beta decay (basically the decay which would release a neutrino can't if there are too many neutrinos already around it), but that won't do anything to trigger a nuclear weapon or nuclear plant meltdown. Even producing enough neutrinos to have a detectable effect at all would require a tremendous amount of energy - attempts to even detect such an effect on earth have been inconclusive. The only place in the universe where the neutron flux gets high enough to actually delay decay for a meaningful amount of time is in the core of a supernova, which is one way heavy elements are produced.