Looking at who would benefit, derailing nuclear power would mainly benefit the US/West globalists They already don't like nuclear, and even more now since nuclear is such a big part of the appeal of joining BRICS. One way to derail BRICS expansion would be to remove nuclear power as an option for these emerging countries. So if desperate enough, the globalist ghouls would deliberately blow up a nuclear plant or two to 'poison the well' for nuclear power generally.
For example, they stage an event where a 'terrorist' group destroys a nuclear plant in an emerging country, thus demonstrating the extreme vulnerability of having nuclear in your country, and the devastating effects if a country's enemies decide to target their shiny new nuke plant. This would instantly reverse the appeal of nuclear power, and thus remove a key motivation for joining BRICS. For emerging countries, nuclear power is extremely attractive and has tons of advantages, but not if the plant can be easily blown up by your regional rivals or domestic enemies. A chunk of your country ends up like Chernobyl -- irradiated and uninhabitable for 1000 years, So these emerging countries decide to forget it, and stick with natural gas, solar, anything but nuclear.
Anyway, this is one possible NWO strategy for not only derailing BRICS expansion, but also for preventing nuclear proliferation. Another broad goal is to prevent emerging countries from modernizing too much, thus keeping them weak and easily exploitable. The globalists mainly are interested in controlling the mineral riches found in these emerging countries, and want the country to have enough infrastructure to facilitate mining operations, etc, but not enough to improve conditions for the general population, which otherwise makes the country too uppity and independent.
Author John Perkins explains the process in his famous book 'Confessions of an Economic Hitman' (link below). The globalists first get the emerging country into serious debt trouble via IMF loans, and then offer debt relief in exchange for control of the country's mineral riches. For decades this IMF con job was the only game in town, but then China entered the picture with far better terms / outcomes for these emerging countries. Hence the wide appeal for joining BRICS -