(IANAL, but here's my reading) You can set them. The difference is, if the DOE is sued over that regulation, the court will make it's own judgement as to what

(IANAL, but here's my reading) You can set them. The difference is, if the DOE is sued over that regulation, the court will make it's own judgement as to what the law intended. Should there be radiation exposure rules? If so, what should the levels be? How should they be measured? What is covered by those rules? The DOE will get its say. But the court would be free to conduct its own research or give whatever weight it wants to the plaintiff's arguments for interpreting the law.