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How robust is HALEU from a nonproliferation perspective?
Shikha Prasad
High-assay low-enriched uranium (HALEU) has emerged as a popular fuel choice for advanced small modular reactors due to its long power production periods before refueling. It is currently being pursued by TerraPower, X-energy, BWX Technologies, Kairos, Oklo, and other reactor companies. HALEU has a uranium-235 enrichment ranging from 5 percent to 20 percent, whereas traditional LWRs use low-enriched uranium fuel enriched up to 5 percent.
HALEU will provide power for longer durations, compared with traditional LWRs. But could it also provide an opportunity for more rapid proliferation, as is speculated in a 2023 National Academy of Sciences report on advanced nuclear reactors (nap.nationalacademies.org/catalog/26630/)?
If a nuclear proliferator conspires to divert fresh nuclear fuel for weapons production when it has not been used in a reactor, the effort required in separative work units (SWUs) to enrich U-235 from 5 percent to 90 percent and that required to enrich from 20 percent to 90 percent are both very small, compared with the effort required to enrich U-235 from its natural abundance to the initial 5 percent.
Rajeev Ranjan, R. K. Singh, S. K. Sikka, Anil Kakodkar
Nuclear Technology | Volume 153 | Number 3 | March 2006 | Pages 341-359
Technical Paper | Reactor Safety | doi.org/10.13182/NT06-A3712
Articles are hosted by Taylor and Francis Online.
This paper highlights a three-dimensional (3-D) transient numerical simulation of the Baneberry event of December 18, 1970, with a 10-kT yield and a 278-m source depth, conducted at the Nevada Test Site. This site has complex geological features with preexisting faults and layered geological strata characterized by a hard Paleozoic layer below the source, and saturated tuff on the west side of the source and clay-rich tuff toward the east side, both overlaid by top alluvial layers. In addition, a layer of 50% montmorillonite is sandwiched between two layers of 20% montmorillonite on the east end. This event is reported to have vented because of fault rupture and shock-wave reflections from a closer hard Paleozoic layer near the source. Here, the shock-induced slip along the preexisting fault plane has an important bearing on the containment efficiency of this event. None of the earlier reported simulation studies address the above slip phenomenon and the influence of variation in geological strata in the presence of the preexisting fault in a 3-D framework for underground nuclear events. The paper describes the capabilities of the SHOCK-3D finite element code for simulating short-time shock-wave propagation, fault rupture leading to sliding along the fault plane, and subsequent crater formation at ground zero with a long-duration transient computation to study the quasi-static behavior of the Baneberry event. Precise modeling schemes of the composite geological strata and fault system demonstrate that a dip-slip mechanism had developed for this event, leading to final venting. The present numerical computation results with SHOCK-3D are in excellent agreement with site observations. In addition, the limitations of earlier reported simulation results from the TENSOR two-dimensional axisymmetric code presented by Terhune et al. have also been overcome.