As others have stated calculus is not needed in operations.

I felt that my calculus training was subpar to my high school education. At the same time theory on neutron life cycle and other aspects of a reactor are more important. If I can tell you what is going to happen to the reactor in next 100+ hours then I don't need to fully understand the engineering that got us here. The basic core material here get's us close, not close enough to get to mastery.

I learned advanced Physics using Algebra and then supplemented that with Calculus. Nothing that I learned in Algebra based Physics was undone by Calculus only augmented. I was pretty good at Physics when I was 17 and got better when I was 18 understanding Calculus.

These are not mutually exclusive ideas.

It's really not quite right to think of the Navy's program as a nuclear engineering one. With their schools to prepare sailors for the boats, they want to make sure everyone knows why and how all protection systems and procedures work, as well as instilling a respect for the severity of radiation exposure and efficacy of protective measures.

The goal isn't designing plants; someone else already did that. It's knowing enough to know why plants were designed the way they were, as well as being able to safely operate, maintain, and fix the thing.

There is some calculus, but calculus really slows things down when you're trying to work through a lot of material.

As others have said, its a nuclear engineering technology education (as an enlistee, anyway). We did use rudimentary calculus, in the form of graphical methods. Given a strip-chart of x(t), and some nonlinear ODE y' = f(x), the student is expected to be able to draw a reasonable approximation of y(t). You get quite a bit of practice with specific ODE's of interest to the power plant, too.