Imagine you are playing with a toy and you accidentally break it. You go to your parents and tell them what happened. They might scold you, but they also want to make sure you don't get hurt and that the broken toy doesn't cause any more problems.
Now, imagine a big machine that creates energy for people to use. This machine is called a nuclear power plant. It's very powerful, but it also has the potential to be very dangerous if something goes wrong. So, just like your parents, there are people called regulators who make sure that the people running the power plant are doing everything they can to keep everyone safe.
The Nuclear Regulation Authority (NRA) is a group of these regulators in charge of overseeing nuclear energy in Japan. They make sure that the companies running the power plants are following strict guidelines, checking for any faults or mistakes, and generally making sure nothing bad happens.
The NRA involves a lot of smart people who study science and engineering to make sure that nuclear energy is used safely. They also make sure that everyone who works in the power plants is trained and ready for any potential problems.
Overall, the Nuclear Regulation Authority is there to make sure that the people of Japan are safe and healthy while enjoying the benefits of nuclear energy.