Exploring Current Constraints on Antineutrino Production by ${}^{241}$Pu and Paths Towards the Precision Reactor Flux Era

Abstract

By performing global fits to inverse beta decay (IBD) yield measurements from existing neutrino experiments based at highly ${}^{235}$U enriched reactor cores and conventional low-enriched cores, we explore current direct bounds on neutrino production by the sub-dominant fission isotope ${}^{241}$Pu. For this nuclide, we determine an IBD yield of $\ddot{I}{ƒ}_{241}$ = 8.16 $\pm$ 3.47 cm${}^2$/fission, a value (135 $\pm$ 58)% that of current beta conversion models. This constraint is shown to derive from the non-linear relationship between burn-in of ${}^{241}$Pu and ${}^{239}$Pu in conventional reactor fuel. By considering new hypothetical neutrino measurements at high-enriched, low-enriched, mixed-oxide, and fast reactor facilities, we investigate the feasible limits of future knowledge of IBD yields for ${}^{235}$U, ${}^{238}$U, ${}^{239}$Pu, ${}^{241}$Pu, and ${}^{240}$Pu. We find that the first direct measurement of the ${}^{240}$Pu IBD yield can be performed at plutonium-burning fast reactors, while a suite of correlated measurements at multiple reactor types can achieve precision in direct ${}^{238}$U, ${}^{239}$Pu, and ${}^{241}$Pu yield knowledge that meets or exceeds that of current theoretical predictions.

13 page, 6 figures