Electrochemical behavior of Ni in an alkaline heavy water electrolyte was studied using cyclic voltammetry and polarized neutron reflectometry. Delays in the hydrogen and oxygen evolution reactions on Ni electrodes and slower kinetics of the reactions in heavy water compared to light water were observed. However, in both 0.01 mol/L NaOH light and heavy water solutions, Ni oxidation and passive film formation occurred at the same potential with similar passive current densities indicating a minor isotope effect of deuterium on passive film formation and growth. Polarized neutron reflectometry detected a passive film growth coefficient of 11.5 ± 1.1 Å/V. The Ni consumption coefficient was determined to be 7.3 ± 1.5 Å/V. Ni oxidation and passive film growth occurred mostly during the transient period after the applied potential increase but was negligible at the steady state. The electric field strength across the passive film was 8 × 10 6 V/cm. The Pilling-Bedworth ratio of the passive film during potentiostatic growth was close to the value of NiO grown on bulk Ni. This work demonstrated the capability of neutron reflectometry in the study of passive films on metals and alloys.

The dissolution of a Ni (111) thin film exposed to a 0.1 M NaCl (pH4) solution was monitored for a period of 816 hours using X-ray reflectometry. The dissolution rate of the Ni (111) film decreased from approximately 9 Å/h at the beginning of the immersion experiment to 0.05 Å/h after 816-hour exposure. After reaching a steady state between formation and dissolution, the thickness of the NiO passive film remained constant at approximately 18 Å during the immersion experiment.

This commitment is reflected in our continued support of technology development and innovation in our current and future energy systems. Our organizations have each supported a variety of research and development activities and initiatives in collaboration with national laboratories, academia, and industry partners that explore and utilize different technologies to meet a variety of energy demands. Nuclear energy is an important part of the global clean energy supply, providing nearly one-third of the world's non-emitting electricity and complementing and enabling other clean energy sources, including renewables. Recognizing this current and future potential for nuclear energy, the Nuclear Innovation: Clean Energy Future (NICE Future) initiative was launched in 2018 at the Ninth CEM in Copenhagen, Denmark. Since its launch, the NICE Future initiative has succeeded in initiating broad, cross-sectoral dialogue among CEM member countries to highlight the roles that nuclear energy can play in bolstering economic growth, energy security, and access, and environmental stewardship. This includes exploring and building awareness about how innovative nuclear energy technologies across both large and small-scale applications, such as small modular reactors (SMRs) and other advanced reactors, can drive clean growth. To explore and communicate the increasingly flexible roles that nuclear energy technologies can play in integrated clean energy systems of the future, the NICE Future initiative proudly launched the Flexible Nuclear Campaign for Nuclear-Renewables Integration (Flexible Nuclear Campaign) at the 10 th CEM in Vancouver, Canada in 2019. The International Energy Agency's (IEA's) 2019 World Energy Outlook forecasts that electricity generation from variable renewables could range from 36% to 67% by 2040. As more renewables connect to the grid, many countries are developing innovative options to employ more flexible operation of traditional and base load energy sources, like nuclear, to produce electricity and heat to meet demand. This report brought together experts from around the globe to share expertise and study opportunities for innovative and advanced nuclear systems to operate flexibly and work in tandem with renewables, contributing to clean energy systems of the future. As demonstrated in technical analyses summarized in this report, nuclear energy offers flexibility in certain electricity markets around the world, and new nuclear technologies could extend the versatility of nuclear energy systems further. At its most basic, nuclear energy can operate flexibly by ramping power output up or down to match grid demand; however, nuclear energy's services extend beyond just electricity generation. Around the world, research is underway to explore how nuclear systems can use generated thermal

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