Material attractiveness of irradiated fuel salts from the Seaborg Compact Molten Salt Reactor

• To deter possible state and non-state actors from misusing nuclear material and technology, accurate knowledge of material attractiveness and weapons usability of uranium and plutonium in Spent Nuclear Fuel (SNF) is crucial. Equipped with this knowledge, nuclear safeguards inspectors can ensure adequate safeguarding of such material at the requisite points in the nuclear fuel cycle. Such assessments are also valuable in the design phase of Nuclear Energy Systems (NES) where they can be incorporated as a part of the Safeguards by Design (SBD) features thereby reducing the burden on operators and the International Atomic Energy Agency (IAEA) by easing future safeguards inspections. Organizations that have accrued significant experiencing in safeguarding the fuel cycle such as the IAEA can use this information to craft effective nuclear safeguards verification frameworks to strengthen the non-proliferation regime by eliminating the possible diversion pathways in the fuel cycle. Over the years, numerous such evaluations of material attractiveness have been performed for Light Water Reactor (LWR) fuel to better understand the nature of the SNF material and its weapons usability at different points in the nuclear fuel cycle. However, availability of such assessments for newer, generation IV reactors such as Molten Salt Reactors (MSR) is severely limited.In the present study we address the gap in knowledge of material attractiveness for such advanced systems and describe the nature of irradiated fuel salts which the nuclear safeguards community might be faced with in the near future as more and more such reactors are anticipated to reach commission and operation. Within the scope of the paper, we use a large database of simulated irradiated fuel salt isotopics (and other derived quantities such as gamma activity, decay heat, and spontaneous fission rates) developed specifically for a MSR concept in order to shed some light on possible weapons usability of uranium and plutonium present in the irradiated fuel salts. This is achieved by using a suitably defined attractiveness metric in a manner similar to what has been implemented for uranium and plutonium separated from LWR spent fuel at different stages in the fuel cycle for a model MSR. The database used in the study has been created by simulating the irradiation of molten fuel salt in a MSR core over a wide range of operational parameters (burnup, initial enrichment, and cooling time, or collectively known as BIC) using the Monte-Carlo particle transport code, Serpent. With the help of this attractiveness metric, the findings from this study have shown that spent fuel from the MSR concept selected in this study is more attractive than that from a conventional LWR. The findings also underscore the need for strengthened safeguards measures for such SNF. These results are expected to be useful in the future for regulatory authorities as well as for nuclear safeguards inspectors for designing a functional safeguards verification routine for irradiated fuel of such unique nature.

Ämnesord

NATURVETENSKAP  -- Fysik -- Subatomär fysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Subatomic Physics (hsv//eng)

Nyckelord

Molten Salt Reactors

nuclear safeguards verification

material attractiveness.

Fysik med inriktning mot tillämpad kärnfysik

Physics with specialization in Applied Nuclear Physics

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