MoD NUCLEAR WEAPON SAFETY PRINCIPLES AND SAFETY CRITERIA (NW SPSC)
MoD Regulations of the Nuclear Weapons Programme,
JSP 538 Issue I – March 2005: Annex F
The NW SPSC is applied to the warhead physics package, and to components within the NW System where a malfunction, accident, energetic explosive reaction or exposure to an adverse environment could lead to release of radioactive material or nuclear yield from the physics package.
The full 22 page report is available here.