A lot of this does not make sense. The NRC usually will just state what the regulation is and not interpret any company procedure. I believe that limit for alcohol by NRC regs is 0.04 BAC. If you tested 0.012 and had already been on site for 4 hours, they back calculate your BAC to when you came on site and determine what your BAC was at that time. If it was over 0.04, then they terminate your access. If it is your first offense and you are an employee, you are offered an opportunity to attend a rehabilitation program. Upon successful completion, your access is restored. If you are a contractor, you are usually terminated. This has been my experience at several utilities. If you are full time employee, go to HR and verify the facts. If you are a contractor or temporary employee, good luck. In any case, you will probably have to rehabilitate.