Concepts for multilateral verification of reductions in nuclear weapons

Whatever vision one may have for how to advance nuclear disarmament, verification needs to be part of it. And, even in a difficult international environment for arms control and disarmament, we don't need to wait before working on verification tools. Indeed, we shouldn't wait. Agreement on instruments such as the Chemical Weapons Convention and the Comprehensive Nuclear-Test-Ban Treaty was greatly facilitated by technical work that began many years before each treaty was negotiated.

Since 2015, the International Partnership for Nuclear Disarmament Verification (IPNDV) has engaged a diverse group of countries to work on technical solutions for verifying key steps that nuclear weapon possessors could take as part of a disarmament agreement. All countries would want confidence in such steps and IPNDV has focused on verification that is multilateral or plurilateral. That is, the process would allow a wide range of countries to participate in and gain assurance from verification.

IPNDV will complete its second two-year work phase in late 2019. Detailed products will be available at www.ipndv.org early in 2020. These, along with products from the first work phase, have developed important concepts and principles that could inform the work of future treaty negotiators.

This article focuses on IPNDV's work on concepts and principles related to verification of the dismantlement of nuclear weapons and of the treatment of nuclear material from dismantled weapons. Of course, the verification of nuclear weapon dismantlement should be part of a broader process of nuclear disarmament, including measures related to fissile material, limits on numbers of nuclear weapons and delivery systems as well as the ban on nuclear weapon tests. IPNDV is also considering some of these aspects, and in Phase II began discussion on how to verify numbers of nuclear weapons held by a country.

IPNDV has advanced its work on verifying nuclear weapon dismantlement using a 14-step conceptual model depicted below. This model is intended to describe all of the possible dismantlement steps until the disposition (disposal or civil reuse) of the resulting nuclear material.

The 14-step model is a valuable analytic tool and has been used to frame verification objectives at each step, possible inspection approaches to achieve those objectives, as well as associated technologies. This sequence of 14 steps is not prescriptive. The steps in an actual process of dismantlement would reflect the specifics of each national nuclear weapons program.

Figure 1: Monitoring and verification activities, as identified by the IPNDV, for the key steps in the process of dismantling nuclear weapons ³

* We make the assumption that there will be declaration at each step in the process.

Verification would aim to provide assurance that a designated number or group of nuclear weapons is dismantled and that the nuclear material is not diverted for re-use in a weapon. Such assurance will rely on the results of on-site inspections carried out by technical specialists. The measures applied by inspectors would track a weapon from its removal from a delivery system until its dismantlement. Dismantlement would be confirmed through measurements to demonstrate the separation of nuclear material from the high explosive components. Specialised measurements on other components to demonstrate that they have been part of a weapon could be possible also. Thereafter, the nuclear material would be tracked through storage and processing to remove sensitive characteristics prior to possible reuse for civil purposes or to enable disposal in a geological repository.

Various measurements would be made at appropriate points through the 14-step process to check that each item under verification is consistent with its declared type or identity. Containment and surveillance measures, as well as physical integrity checks of storage buildings would aim to deter and detect any diversion of items under verification. Confidence that dismantlement of a nuclear weapon has taken place will result from an amalgam of many observations, with different inspection findings reinforcing each other and, as needed, compensating for limits on procedures and technologies at given steps. Confidence should also grow as the dismantlement process is followed over time.

The main challenge for the design of verification arrangements is to create procedures and technical tools that are effective and efficient but which do not disclose information that might pose a risk for nuclear weapons proliferation, or that might affect the safety or security of nuclear weapons and related facilities. IPNDV has put special emphasis on ensuring that parties to the Treaty on the Non-Proliferation of Nuclear Weapons (NPT) can act in accordance with non-proliferation obligations. IPNDV partners judge that verification can be done consistently with these obligations where inspection teams include members from non-nuclear weapons states.

IPNDV will decide in late 2019 on the scope of its third work phase. Conceptual work of the kind described here will continue, but should be complemented by additional exercise-based activities to test and refine the work done so far.

3 www.ipndv.org/reports-analysis/deliverable-2-assessment-monitoring-objectives-information-requirements-basic-dismantlement-scenario/