A reactive scientific research institute is a group of really smart grown-ups who spend a lot of time learning and figuring out things about the world.
However, unlike regular scientists who may study something just for fun or because they think it is interesting, reactive scientific researchers study things that are happening right now and that we need to solve.
For example, if there is a new virus that is making people sick, reactive scientific researchers will study it to figure out how to stop it from making people sick. Or if there is a natural disaster, like a hurricane, reactive scientific researchers will study what happened and figure out how we can be better prepared for the next time something like that happens.
In a way, reactive scientific researchers are like superheroes because they use their smarts to help people and make the world a better, safer place to live.