Using external ion irradiations for simulating self-irradiation damage in nuclear waste glasses: State of the art, recommendations and, prospects

Abstract

Due to the complexities associated with handling and characterizing the radiation damage in radioactive materials such as nuclear waste forms, ion irradiation has been widely used to simulate the effects of the selfirradiation damage. This often involves ion irradiation of nuclear waste surrogate glasses using ion accelerators. Such facilities allow using a wide range of ion types ranging from H to U and energies from tens of keV to hundreds of MeV. For various reasons, the researchers often have to use ions and energies that do not necessarily match with what is expected in actual nuclear waste forms. Due to a lack of detailed and dedicated studies, there are currently no guidelines or consensus regarding the use of the ion irradiation as a means of simulating the self-irradiation damage. The purpose of this article is to delve into this subject by presenting systematic studies of a number of glasses carried out in the last decade or so. By doing so, guidelines and easy to follow ion-mass Vs ion energy contour maps are provided to best simulate the long-term radiation damage in nuclear waste forms. We also discuss how the ions of different masses and energies can be exploited for defect healing and provide a roadmap to undertake systematic studies on this subject. For the sake of brevity, a quick summary of important results and the guidelines is presented towards the end of this article and not here. Besides the nuclear waste community, the study is also of interest to a wide research community dealing with defect formation and defect healing in glasses for use in radiation environments experienced in nuclear reactors, decommissioning and space applications to name a few.

Radiation damage effects on the structure and properties of radioactive waste glasses

“…There are more countries embarking (considering, planning or starting) on nuclear power programmes in the future [2]. With the growing energy demands and increasing greenhouse gas emissions, nuclear power is considered as one of the main candidates to meet the energy demands with very low or negligible carbon footprints [3]. This inventory of waste requires safe, effective and economic management for the sustainable utilisation of nuclear energy [3,6,7].…”

“…These complexities present incredible challenges to accurately simulate and study the effects of radiation damage in HLW glasses and consequently many different approaches, methods and techniques have been employed to simulate and study the effects of self-irradiation damage in HLW glasses [3]. These include ion beams from accelerators or TEM to simulate the electronic energy losses of alpha, beta particles and gamma photons, as well as losses due to elastic collisions or ballistic interactions of alpha recoil nuclei [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35].…”

“…Typically, the individual effects of electronic interactions due to beta/gamma and alpha particle or nuclear interactions due to alpha recoil nuclei are studied. A few reports, however, have presented the effects of mono-, simultaneous and sequential ion irradiations [3,36,37]. These studies have given great insight and provide motivation to review self-irradiation damage in nuclear waste glasses by considering the effects of dose and dose rate, and effects of mass and energy in accurately predicting the evolution of nuclear waste glasses [3,[36][37][38].…”

“…A few reports, however, have presented the effects of mono-, simultaneous and sequential ion irradiations [3,36,37]. These studies have given great insight and provide motivation to review self-irradiation damage in nuclear waste glasses by considering the effects of dose and dose rate, and effects of mass and energy in accurately predicting the evolution of nuclear waste glasses [3,[36][37][38]. Another method to study the effects of radiation damage which is reported in the literature is doping of HLW glass with a short-lived actinide such as 244 Cm or 238 Pu [13,24,30,39].…”

“…It has been established that electronic effects due to interactions with beta/gamma from the decay of fission products will be responsible for self-irradiation damage in the first ~ 500 years of geological disposal [3,24,40]. The decay of fission products will also produce radiogenic heating which will increase the temperature (as high as 670 K for the UK HLW form) of the waste form ( [37,41].…”