As explained in my answer on 14 December 2009, Official Report, column 825W, the Nuclear Weapon Regulator is an officer within the Defence Nuclear Safety Regulator (DNSR). The mission/objective of DNSR is to regulate the nuclear and radiological safety of the defence nuclear programmes so that they are managed with due regard for the protection of the work force, the public and the environment. As an individual, the Nuclear Weapon Regulator does not have a mission separate from that of the DNSR team as a whole.
The Nuclear Weapon Regulator’s terms of reference are in the form of a letter of delegation from the head of DNSR which provides regulatory authority:
To give permission for nuclear activities on the basis of formal safety submissions, reviews and inspections.
To approve/agree nuclear safety submissions and safety management arrangements.
To offer formal regulatory advice to the authorisee’s representatives.
To direct the postponement or cessation of specific nuclear weapons programme activity.
To assess the demonstration of emergency arrangements.