Deep borehole disposal (DBD) has been suggested as an option for disposing spent nuclear fuel in a number of countries, including several countries that are subject to international safeguards. While potential benefits of deep borehole disposal include increased safety, reduced cost, and greater flexibility, the method could also impact the implementation of international safeguards. DBD presents some unique safeguards challenges compared to a conventional MGR. These challenges include 1) verifying borehole design below the surface; 2) strong reliance on CoK up to and including disposal; 3) limitations on the ability to observe or verify successfully emplaced canisters; and 4) successfully monitoring a closed and sealed DBD facility over the long term. In some cases, such challenges may prove easier for a DBD facility than for a conventional MGR, others more difficult, and still others may require new methodologies (or existing methodologies newly applied to safeguards). Long-term monitoring in particular might be somewhat less onerous.
The goal of the field trial of EDAS was to demonstrate the utility of secure branching of operator instrumentation for nuclear safeguards, identify any unforeseen implementation and application issues with EDAS, and confirm whether the approach is compatible with operator concerns and constraints.
The data authentication task is concerned with the ability of a user to trust the output from an unattended measurement of spent nuclear fuel intended for disposal. Five high-level requirements that are driven from a data authentication perspective need to be considered for instrument development: The instrument must be secured. All data emerging from the instrument must be signed. Instrument inputs may also need to be signed and authenticated. The instrument environment needs to be controlled. A vulnerability assessment will be necessary for the full system before deployment. Additional requirements may be necessary, especially if operational scenarios include arrangements for joint use. None of the prototype instruments currently under development yet satisfies any of these requirements. From a data authentication perspective, the selection of a preferred instrument from among the candidates under development should consider the relative ability to secure the instrument, its relative needs for ancillary instrumentation, and ability of the instrument to self-interrogate its state of health. Further work is recommended to develop advanced technologies, methods and approaches for tamper indication. Beyond the development of any particular instrument for the nondestructive assay of spent fuel, efforts should be devoted to developing the system for spent fuel verification prior to long term disposal, including likely operational scenarios for routine use of the verification system.
The overall spent fuel nondestructive assay project seeks to develop improved measurement capability for the verification of spent nuclear fuel, especially before its disposal or movement to hard-to-access storage. Various systems are being considered, employing neutron and/or gamma radiation detection with either passive or active methods; their use scenarios are not yet well defined. In a practical deployment, the measurement system would likely need to operate in unattended mode. The output results may also need to be shared between multiple recipients with various interests. The data authentication task considers what issues are important in being able to trust the measurement results. By defining and analyzing a generic (3z(Bbaseline(3y (Bsystem scenario, we have identified five key factors needing specific attention: application use-case details, equipment tamper indication, supporting (ancillary) instruments, systems implementation, and instrument state-of-health reporting.