R. S. Kemp | Searcharxiv

arXiv2025

Modelling reliability under deep decarbonisation of the European electricity grid

Conventional feasibility studies of deep decarbonisation are often limited in their temporal scope, and are thus unable to draw conclusions about grid reliability over multi-decadal time periods. To address this problem, we introduce RESCORE, a fast and transparent model that uses 43 years of hourly weather data to evaluate both the cost and reliability characteristics of low-carbon electricity mixes. Applying RESCORE to the European electricity grid, we show that infrequent but extreme weather events play an outsized role in setting the cost for generation mixes without dispatchable backup: reliably meeting the last 1% of demand accounts for about 36% of the entire system cost when the mix contains only solar, onshore wind and storage. We also show that by including small amounts of low-cost, dispatchable generation (e.g., natural gas, hydro, or similar) the cost of a reliable, high-renewables grid can be drastically reduced.

econ.GN↗

arXiv2025

LiDAR for Robust Exoatmospheric Positioning

We present an active method for robust exoatmospheric positioning using space-based intensity modulated direct detection (IMDD) LiDAR with a spacecraft-based transmitter and receiver and a constellation of orbital reflectors. We discuss the precision of the method, the power requirements, the advantages of such a method over existing GPS/GNSS systems, and potential applications.

physics.ins-det↗

arXiv2024

Assessing the Risk of Proliferation via Fissile Material Breeding in ARC-class Fusion Power Plants

Construction of a nuclear weapon requires access to kilogram-scale quantities of fissile material, which can be bred from fertile material like U-238 and Th-232 via neutron capture. Future fusion power plants, with total neutron source rates in excess of $10^{20}$ n/s, could breed weapons-relevant quantities of fissile material on short timescales, posing a breakout proliferation risk. The ARC-class fusion reactor design is characterized by demountable high temperature superconducting magnets, a FLiBe liquid immersion blanket, and a relatively small size ($\sim$ 4 m major radius, $\sim$ 1 m minor radius). We use the open-source Monte Carlo neutronics code OpenMC to perform self-consistent time-dependent simulations of a representative ARC-class blanket to assess the feasibility of a fissile breeding breakout scenario. We find that a significant quantity of fissile material can be bred in less than six months of full power operation for initial fertile inventories ranging from 5 to 50 metric tons, representing a non-negligible proliferation risk. We further study the feasibility of this scenario by examining other consequences of fissile breeding such as reduced tritium breeding ratio, extra heat from fission and decay heat, isotopic purity of bred material, and self-protection time of irradiated blanket material. We also examine the impact of Li-6 enrichment on fissile breeding and find that it substantially reduces breeding rate, motivating its use as a proliferation resistance tool.

physics.soc-ph↗