The main issues that need to be considered when verifying the dismantlement of nuclear warheads, are counting and avoiding theft. To do this, it is necessary to ensure the chain of traceability and monitor the access portal to the storage site. Several technical solutions have been implemented (managed access, use of labels and seals, information barrier). During exercises between the United Kingdom and Norway (UKNI, United Kingdom–Norway Initiative), the unexpected result was that human factors could also have a decisive influence on the verification process and its results. This is likely due to the fact that the verification process is characterized by a constant tension between trust, perceived as an evidence-based judgment by informed actors, and confidence, perceived as the perception of intentions in a situation where evidence is lacking [BOW 18].
Some experimental simulations on disarmament verification have been carried out. The design of this simulation was the key element of the preparatory work that formed the basis of the research and required a considerable investment of time and resources. However, this approach offers a flexible way to recreate real-life challenges and problems in an artificial environment that can be, in part, controlled and targeted.
In these simulations, everything from the attitude of the host team, to the manner and speed with which information was provided, was a potential indicator of intentions and was incorporated into the research participants’ interpretation scheme. This intellectually demanding cognitive process encompassed the more objective and scientific, evidence-based approach that all participants aspired to experience. Since trust is indeed a crucial influence on the results of verification, it would be simplistic, even dangerous, to only view verification in terms of a purely technical nature, based only on scientific evidence [BOW 18].
1.5.1.2. Technologies at the service of disarmament
Future nuclear arms reduction efforts will require technologies that can verify that the warheads to be dismantled are genuine, without revealing any sensitive warhead design information to international inspectors.
How can a claim be proved about an extremely sensitive object, a nuclear weapon, for example, without revealing information about it? This paradox has been challenging the control of nuclear weapons for more than five decades. A mechanism in the form of an interactive evidence system has been proposed, that can validate the structure and composition of an object, such as a nuclear warhead, with arbitrary precision, without revealing its structure and composition [KEM 16].
Confirming the authenticity of nuclear warheads and their components is at the heart of the challenge of verifying future reductions in nuclear arsenals. An overview of the development of verification systems and the challenges and opportunities highlighted for future research in this area are provided in [YAN 15].
For a long time, low-resolution gamma spectrometry (sodium iodide crystal probes) has been used in verification systems. Thus, the programs CIVET (Controlled Intrusiveness Verification Technology) from 1998 to 1991, TRIS (Trusted Radiation Identification System) from 1999 to 2001 and NG-TRIS (Next Generation Trusted Radiation Identification System) since 2007 have been successively used. Since 1984, the FNMIS (Fieldable, Nuclear Material Identification System) has used neutron activation. The parameters most frequently sought are the presence of plutonium, its various isotopes, its mass or its age, and sometimes the presence of uranium 235, its enrichment or its mass. Recently, some authors have proposed the use of intensities of nuclear resonance fluorescence (NRF) close to 2.2 MeV to distinguish between real computer objects and hoax objects, with great confidence and realistic measurement times [VAV 18].
A concept that exploits isotope-specific nuclear resonance phenomena in order to authenticate the fissile components of a warhead by comparing them to a previously authenticated model, has been submitted [HEC 18].
Most of the plutonium in the world resides inside the rods of spent fuel from nuclear reactors. Only the United States, France and Japan have isolated and stored plutonium. This high-activity radioactive waste is generally stored long term in large, heavily shielded casks. The measurements of the diffusion angles of cosmic muons that pass through a storage cask can be used to determine whether the radioactive waste in the casks is in the form of intact spent fuel assemblies, or whether the plutonium has been recovered by reprocessing, without opening the cask [DUR 18].
1.5.2. NPT controls
The NPT has been the subject of an impressive number of agreements between states and the IAEA to improve disarmament controls. While there have been some successes, there have unfortunately been some resounding failures.
1.5.2.1. NPT guarantees
The UN has entrusted the IAEA with the task of monitoring the application of the NPT, known as safeguards. States are divided into three groups, the five nuclear-weapon states (NWS), the non-nuclear weapon states (NNWS) and the three states (India, Israel and Pakistan) that have not signed the NPT Treaty.
There are four main types of guarantee agreements: General Guarantee Agreements (GGAs), Limited Guarantee Agreements, Voluntary Submission Agreements (VSAs) and emergency measures.
The Generalized Guarantee Agreements concern all the NNWS and the text is the result of compromises, in order to encourage the NNWS to adhere to this new control regime. In order to provide an appropriate and identical legal framework for all signatories, a model Comprehensive Safeguards Agreement, INFCIRC/153 (corrected 1983), was developed in 1971 [AIE 75] by a committee of experts from IAEA Member States. This GGA is currently in progress with 174 NNWS. However, because of Iraq’s clandestine military nuclear program, in 1997 it was decided to reinforce the verification standard by an Additional Protocol (AP, i.e. INFCIRC/540) [IEA 97]. This AP – which remains optional – ensures faster access to suspect sites for IAEA inspectors and better control of nuclear materials. As of December 2015, the IAEA had concluded five VSAs and APs, 173 GGAs, 121 APs and three Elemental Agreements. As of December 21, 2018, 134 states have adhered to the AP standard and 14 are in the process of implementation [COL 18].
Limited Warranty Agreements are reserved for certain states (India, Israel, Pakistan), which have not signed the NPT. They have concluded more limited safeguards agreements with the Agency (of the INFCIRC/66 type), which only apply to nuclear material, equipment, non-nuclear material and facilities specified by the agreement (thus designated by the state).
Voluntary Submission Agreements (VSAs) are reserved for NWS that are not required to enter into a safeguards agreement with the Agency. All five states have done so. France, for example, has signed a safeguards agreement modeled on the Comprehensive Safeguards Agreements concluded between the IAEA and the NNWS. Under this agreement (INFCIRC/290), signed on July 27, 1978, France subjects the nuclear material it designates in selected facilities, or parts of facilities, to IAEA safeguards. To take account of the safeguards exercised by the EURATOM, the safeguards agreement concluded by France is trilateral in nature, with EURATOM being a party to the agreement.
The emergency measures decreed by the IAEA concerned three points (declaring a new nuclear installation within 180 days; declaring international transfers and the production of uranium and thorium concentrates; effectively resorting to special inspections) [IRS 19a].
IAEA controls under the NPT Treaty are called “purpose” controls. Their objectives are to ensure that nuclear material in the agency’s custody is not used for non-peaceful purposes. Since the Additional Protocols’ entry into force, the agency’s controls are no longer limited to nuclear material, but extend to the provision of information concerning the nuclear industry.
1.5.2.2. The various types of collaboration between states to verify disarmament
Article VI of the NPT states, among other things, that each party to the NPT must undertake effective measures in the field of arms control and