Use of CEvNS to monitor spent nuclear fuel

Increasing amounts of spent nuclear fuel (SNF) are stored in dry storage casks for prolonged periods of time. To date no effective technology exists to reverify cask contents should this become necessary. We explore the applicability of coherent-elastic neutrino-nucleus scattering (CEvNS) to monitor the content of SNF from dry storage casks. SNF produces neutrinos chiefly from ${}^{90}\mathrm{Sr}$ decays. We compare these results with what can be achieved via inverse beta decay (IBD). We demonstrate that at low nuclear recoil energies CEvNS events rates exceed the IBD event rates by 2–3 orders of magnitude for a given detector mass. We find that a 10 kg argon or germanium detector 3 meters from a fuel cask can detect over 100 events per year if a nuclear recoil threshold under 100 eV can be achieved.

Figure 1

Event rate of CEvNS for a ${}^{184}\mathrm{W}$ and ${}^{28}\mathrm{Si}$ detector able to resolve 0 eV [red] or 10 eV [blue], compared to the IBD event rate of a detector the same size. The detector mass is 10 kg, the standoff is 3 m and data taking period is one year from a 10 MTU source.

Figure 2

CEvNS event rate as a function of the atomic mass of an isotope, with labeled nuclear recoil thresholds. High mass isotopes have high event rates at low recoil thresholds and at high thresholds low mass isotopes perform best. The detector mass is 10 kg, the standoff is 3 m and data taking period is one year from a 10 MTU source.

Figure 3

$1\sigma$ error as percentages for ${}^{40}\mathrm{Ar}$, ${}^{74}\mathrm{Ge}$, and ${}^{184}\mathrm{W}$ as a function of background levels. Solid lines indicate the $1\sigma$ errors of each isotope at a recoil energy threshold of 10 eV, while dotted lines of the same color indicate the $1\sigma$ errors at a 50 eV threshold. The detector mass is 10 kg, the standoff is 3 m and data taking period is one year from a 10 MTU source.