A new IAEA publication has been published (May 2021) (link here) . This has the objective to provide comprehensive, detailed guidance for States, competent authorities and operators to assist them in implementing the recommendations from the IAEA on the Physical Protection of Nuclear Material and Nuclear Facilities. This area is subject to the Convention on the Physical Protection of Nuclear Material (link here). The UK signed on to this, with some reservations as a member of the EU. I cannot establish the current position.
A Physical Protection System (PPS) is an integrated system of detection, delay and response measures. It should comprise people, procedures and equipment to provide defence in depth, with a graded approach, to address the range of threats identified in the applicable threat statement and to protect against both unauthorized removal and sabotage. The PPS comprises interior and exterior intrusion detection sensors, cameras, delay measures, access controls devices and response measures.
The handbook recommends a systematic design and evaluation of the PPS with requirements identification, design, and evaluation phases. These stages are each explained in some detail. This process is fine if you are starting afresh on a new site but, with an old site, you are more likely to be trying to combine systems with a range of ages and technologies into a workable and justifiable system. The principles need to be modified a bit for this circumstance.
The handbook advises on how to deter an attack on a site by making potential adversaries think it an unattractive target because of low probability of success or high risks to themselves.
There are detailed sections on physical protection systems (design, evaluation, testing and technology options) and the management systems required to keep it all operating effectively.
This handbook would be a good read for any security manager and security systems designer.