Title: Helium interactions with alumina formed by atomic layer deposition show potential for mitigating problems with excess helium in spent nuclear fuel

Abstract

Helium gas accumulation from alpha decay during extended storage of spent fuel has potential to compromise the structural integrity the fuel. We report results obtained with surrogate nickel particles which suggest that alumina formed by atomic layer deposition can serve as a low volume-fraction, uniformly-distributed phase for retention of helium generated in fuel particles such as uranium oxide. Thin alumina layers may also form transport paths for helium in the fuel rod, which would otherwise be impermeable. Micron-scale nickel particles, representative of uranium oxide particles in their low helium solubility and compatibility with the alumina synthesis process, were homogeneously coated with alumina approximately 3–20 nm by particle atomic layer deposition (ALD) using a fluidized bed reactor. Particles were then loaded with helium at 800 °C in a tube furnace. Subsequent helium spectroscopy measurements showed that the alumina phase, or more likely a related nickel/alumina interface structure, retains helium at a density of at least 10¹⁷ atoms/cm³. High resolution transmission electron microscopy revealed that the thermal treatment increased the alumina thickness and generated additional porosity. Results from Monte Carlo simulations on amorphous alumina predict the helium retention concentration at room temperature could reach 10²¹ atoms/cm³ at 400 MPa, a pressure predictedmore » by others to be developed in uranium oxide without an alumina secondary phase. This concentration is sufficient to eliminate bubble formation in the nuclear fuel for long-term storage scenarios, for example. Finally, measurements by others of the diffusion coefficient in polycrystalline alumina indicate values several orders of magnitude higher than in uranium oxide, which then can also allow for helium transport out of the spent fuel.« less

Authors:

Zhang, Shenli ^[1]; Yu, Erick ^[1]; Gates, Sean ^[2]; Cassata, William S. ^[2]; Makel, James ^[3]; Thron, Andrew M. ^[1]; Bartel, Christopher ^[4]; Weimer, Alan W. ^[4]; Faller, Roland ^[3]; Stroeve, Pieter ^[3]; Tringe, Joseph W. ^[2]

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+ Show Author Affiliations

1. Univ. of California, Davis, CA (United States). Dept. of Materials Science and Engineering
2. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
3. Univ. of California, Davis, CA (United States). Dept. of Chemical Engineering
4. Univ. of Colorado, Boulder, CO (United States). Dept. of Chemical and Biological Engineering

Publication Date:

Sun Nov 26 00:00:00 EST 2017

Research Org.:

Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States); Univ. of California, Davis, CA (United States)

Sponsoring Org.:

USDOE Office of Nuclear Energy (NE)

OSTI Identifier:

1476185

Alternate Identifier(s):

OSTI ID: 1549135

Report Number(s):

LLNL-JRNL-743180
Journal ID: ISSN 0022-3115; 886825

Grant/Contract Number:  

AC52-07NA27344; NE0000704; DE–NE0000704

Resource Type:

Accepted Manuscript

Journal Name:

Journal of Nuclear Materials

Additional Journal Information:

Journal Volume: 499; Journal ID: ISSN 0022-3115

Publisher:

Elsevier

Country of Publication:

United States

Language:

English

Subject:

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS; helium; ALD; alumina; fuel