Nuclear Security: The Challenges of Physical Protection Systems

By Mr. Benjamin Hautecouverture, Senior Research Fellow at the Fondation Pour la Recherche Stratégique

Physical protection systems (PPS) for nuclear materials and equipment are at the heart of nuclear security architectures against the risk of terrorism. As the first Conference of the Parties to the amendment of the Convention on the Physical Protection of Nuclear Material (A/CPPNM) in 2022 draws nearer, it should be remembered that the challenges of implementing such systems are operational, regulatory, and strategic.


According to the International Atomic Energy Agency (IAEA) recommendations,1 a PPS is a system of measures against unauthorized removal and sabotage. It comprises human resources, procedures, and equipment “to provide defence in depth, with a graded approach, to address the range of threats identified in the applicable threat statement.”2

To be effective, a PPS must fulfill these four complementary functions: deterrence, detection, delay, and response (DDDR).

The “deterrence” function is said to be functional if a PPS allows an attacker to estimate that a protected device is not a valid target because its chances of success are too low or the cost of the operation is too high.

The “detection” function covers the full range of actions from sensor activation to the indication of proven malicious activity.

The “delay” function slows down the progress of an attacker to increase the reaction time of the intervention forces.

Finally, the “response” function is the one that allows the neutralization of the attacker before he can reach his target.

A long-standing concern

The issue of physical protection does not date from the increase in the volume of violence in terrorist enterprises in the 1990s. In particular, the first CPPNM was adopted in October 1979 and entered into force eight years later. At that time, the development of nuclear energy for peaceful purposes was taking off, and the harmonization of security procedures was beginning to be seen as an inter-state issue commensurate with the risk.

That said, it was the combination of the risk of terrorism and the collapse of the Soviet Union leading to an increased risk of nuclear proliferation in the 1990s that brought the issue of PPS into the public arena twenty-five years ago. According to Dr. Mohamed ElBaradei in 1997,3 “the importance of having effective physical protection systems in place has been highlighted by the threat posed by the well-publicized illicit trafficking incidents in the mid-1990s. These incidents pointed to the possibility of unauthorized access to direct use material and to potential weaknesses in the physical protection system.”4

As pointed out by the US Department of Energy in Partnership for Nuclear Security, released in 1998,5 many deficiencies in the Russian PPS for nuclear materials were identified at the time: poor defenses of facilities; inadequate central alarm stations capabilities; ineffective detection of intrusion; poor access control; inadequate fences; lack of portal monitors to detect fissile materials leaving a site; or even ineffective protection of guards against the risk of small-arms fire from intruders. To some extent, these shortcomings, then linked to the disintegration of the Soviet administrative system, have since been mirrored in countries newly promoted to the peaceful uses of nuclear energy but without a security culture to accompany them.

Technical and political challenges

The IAEA's recommendations for the design of PPSs advocate the use of a “systems engineering approach”,6 designed to build complex architectures through the participation of specialists from complementary disciplines.

That involves identifying the objectives and specifications of a given system (risk analysis, threat assessment or “design basis threat”, location of potential targets, regulatory framework of an installation, etc.), designing it (in its three DDR functions), and being able to evaluate it (verification and performance tests, in particular).

At the heart of the design of a PPS is the notion of “defense in depth”: the layering of protection around an identified target, so that each layer combines with the others to increase the overall effectiveness of the system. That is the reason why, for example, there is no reason, a priori, to be overly moved by a successful intrusion of demonstrators into a nuclear facility, as the general press may do from time to time, by maintaining the idea that the physical protection systems put to the test would be insufficient. This key notion is complemented by those of “graded approach”, “robustness”, and “balanced protection”.

Insider threats

The particular case of insider threats has been identified in recent years as one of the main risks of undermining properly implemented PPS. This corresponds to a certain logic: the more robust the PPS, the less likely it is that frontal attacks from the outside will succeed. It is, therefore, a matter of an attacker bypassing them from the inside. Moreover, this logic partly corresponds to reality. Indeed, the various databases7 on incidents concerning nuclear and radioactive materials indicate that the events of loss or theft of highly enriched uranium (HEU) and plutonium (Pu) involve, directly or indirectly, an employee of the installation. These risks have increased in various ways during the global health crisis since winter 2020/2021. Naturally, the practice of security surveys before hiring personnel to work in secure environments should be a standard for all nuclear operators. Regular renewal of these surveys is also to be recommended, but this cannot be the alpha and omega of an approach to human resources management. Theft events are often linked to very personal behavioral factors (financial worries, accumulation of professional resentments, etc.). Finally, the quantity and form of the materials available are determining variables: the smaller the quantity available, the more likely it is that the attempted theft will go unnoticed.8

The 2022 A/CPPNM revcon is an opportunity

The Convention on the Physical Protection of Nuclear Material (CPPNM) is the more relevant framework for ensuring the physical protection of nuclear material used for peaceful purposes while in international transport. As a reminder, the 2005 Amendment to the CPPNM usefully extends the scope of the Convention to cover material and facilities in domestic use, storage and transport, and risks of sabotage. The amended Convention entered into force in 2016 and was due to hold its first review conference five years later, this year in 2021.9 The meeting has been postponed until next year.10 It will first be a milestone to assess the extent to which the issue of PPS is of concern to the States Parties. It will then be a major opportunity to adapt the international response to the evolution of the threat but also of the security practices, processes, and technologies employed. Incidentally, it would be good if this first review conference was an opportunity to take the decision to hold regular review conferences in the future, which will help support the effective implementation of the provisions of the amended Treaty. For the time being, the amended CPPNM cannot yet be considered the cornerstone for a truly global physical security regime for nuclear materials and facilities. Such a regime now needs to be put in place.11

1Handbook on the Design of Physical Protection Systems for Nuclear Material and Nuclear Facilities, IAEA Nuclear Security Series No. 40-T, 200pp., Vienna, 2021.

2 Ibid., p.4.

3 Dr. Mohamed ElBaradei was Director General of the IAEA from 1997 to 2009.

4 Dr. Mohamed ElBaradei, Keynote Speech, IAEA “International Conference on Physical Protection of Nuclear Materials: Experience in Regulation, Implementation and Operations,” IAEA-CN-68, November 1997, Vienna.

5 U.S. Department of Energy (DOE), Partnership for Nuclear Security: MPC&A Program Strategic Plan, Washington, D.C., January 1998.

6 Handbook on the Design of Physical Protection Systems for Nuclear Material and Nuclear Facilities, Op.cit., p.6.

7 See for instance the Incident and Trafficking Database (ITDB) of the IAEA since 1995.

8 See for instance Rajeswari Pillai Rajagopalan, “Insider Threats and Nuclear Security During a Pandemic”, The Diplomat, 23 April, 2021.

9 Article 16.

10 The Conference of the Parties to the Amendment to the CPPNM shall take place in the week of 28 March 2022.

11 See for instance, Samantha Neakrase, “Strengthening Nuclear Security with a Sustainable CPPNM Regime: An Ambitious Review of theAmended CPPNM,” paper prepared for the 2020 IAEA International Conference on Nuclear Security (January 2020).


Benjamin Hautecouverture is a historian and a political scientist, a senior research fellow at the Fondation pour la recherche stratégique (Paris, France). He is Senior Fellow at the Canadian Global Affairs Institute, Technical Director at Expertise France, and one of the founders of the European Union Consortium on Non-Proliferation and Disarmament.