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Watanabe Naoko

Faculty of Engineering　Applied Quantum Science and Engineering　Quantum Energy EngineeringProfessor
Institute for Academic InnovationProfessor

Researcher basic information

■ Degree
  • PhD, University of California, Davis
■ URL
researchmap URLホームページURL■ Various IDs
J-Global ID■ Research Keywords and Fields
Research Keyword
  • Decommissioning
  • 放射性セシウム
  • MD計算
  • 有機物
  • 土壌
  • 収脱着
  • 物質移行
  • 腐食
  • 放射性廃棄物
  • ベントナイト
  • オーバーパック
  • 放射性廃棄物処分
Research Field
  • Energy Engineering, Nuclear engineering
■ Educational Organization

Career

■ Career
Career
  • 2013
    Hokkaido University, 工学(系)研究科(研究院), 准教授

Research activity information

■ Papers
■ Other Activities and Achievements
■ Syllabus
  • 原子力・エネルギーシステム特論, 2024年, 修士課程, 工学院
  • 放射性廃棄物処分工学特論, 2024年, 修士課程, 工学院
  • 大学院共通授業科目（一般科目）：自然科学・応用科学, 2024年, 修士課程, 大学院共通科目
  • 放射性廃棄物処分工学特論, 2024年, 修士課程, 工学院
  • 原子力・エネルギーシステム特論, 2024年, 博士後期課程, 工学院
  • 放射性廃棄物処分工学特論, 2024年, 博士後期課程, 工学院
  • 放射性廃棄物処分工学特論, 2024年, 博士後期課程, 工学院
  • 化学Ⅰ, 2024年, 学士課程, 全学教育
  • 一般教育演習(ﾌﾚｯｼｭﾏﾝｾﾐﾅｰ), 2024年, 学士課程, 全学教育
  • 工業英語演習, 2024年, 学士課程, 工学部
  • エネルギー工学概論, 2024年, 学士課程, 工学部
  • 科学・技術の世界, 2024年, 学士課程, 全学教育
■ Research Themes
  • Geological disposal of high-level radioactive waste - Alteration of clay buffer material into Copper-type and its effect on migration behavior of radionuclides
    Grants-in-Aid for Scientific Research
    01 Apr. 2025 - 31 Mar. 2028
    小崎 完; 渡辺 直子
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), Hokkaido University, 25K08522
  • 原子力発電で発生する混合廃棄物の安全性評価指標の構築に向けた基礎的研究
    科学研究費助成事業
    01 Apr. 2023 - 31 Mar. 2026
    渡辺 直子; 森永 祐加; 植松 慎一郎; 小崎 完; 湊 大輔
    商用原子力発電所の廃止措置の進展に伴い、解体廃棄物に加えて、発電所に保管されている運転廃棄物の処理・処分が必要となる。これらの廃棄物には、放射性核種に加えて、鉛、六価クロムなどの重金属、PCB、アスベスト、高濃度の塩など環境影響物質が混在する混合廃棄物が含まれるが、現状では混合廃棄物の処理・処分のルートは確定していない。本研究では、放射性廃棄物全体の中での各環境影響物質の潜在的危険度を把握した上で、優先順位の高い代表的な環境汚染物質を抽出してセメントによる固定化やバリア材による保持など、相互作用のメカニズムに関する基礎研究を行う。
    令和5年度には、高濃度の塩を含むセメント固化体に着目し、放射性核種のセメントによる固定可能を評価する手法を確立した。その手法を用いて、高濃度の硫酸ナトリウムを含有するセメント固化体からのCs-137の脱離挙動を評価し、セメントの微細構造との関係正から検討した。その結果、Cs-137を未水和のセメントと混錬しセメントの水和反応が進行する過程にCs-137が共存することで、水和後のセメントに収着させる場合よりも収着分配係数が一桁大きくなること、Cs-137の収着における硫酸ナトリウムによる影響は顕著ではないことがわかった。
    今後は、核種及び有害物質の種類を増やし、セメントによる核種、有害物の固定化のメカニズムについて評価するとともに、合理的・効果的な安全性評価指標について検討する。
    日本学術振興会, 基盤研究(C), 北海道大学, 23K04626
  • Development of performance assessment method for barrier materials in geological disposal of radioactive waste using multifunctionalized gold nanoparticles
    Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)
    01 Apr. 2018 - 31 Mar. 2021
    KOZAKI Tamotsu
    As a fundamental study on the migration behavior of colloidal radionuclides in a geological disposal environment, batch and column experiments were conducted using gold nanoparticles (AuNP) of different sizes coated with polyethylene glycol to study the interactions of AuNPs with silica sand and Na-type montmorillonite. The transport of AuNP was observed to be increased for the smaller nanoparticles, which exhibit increased stability against aggregation. These results suggest interactions other than electrostatic and vdW, including steric effects provided by the PEG coating can control the transport behavior in porous media such as silica sand.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), Hokkaido University, 18K04990
  • Decommissioning Scenario Evaluation for Cost-Effective Demolition of Concrete Structures of Nuclear Power Plants
    Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)
    01 Apr. 2016 - 31 Mar. 2019
    Watanabe Naoko; YANAGIHARA Satoshi
    Decommissioning cost for 1100 MWe BWR nuclear power plant was analyzed comparing multiple scenarios for the purpose of evaluating cost-effective ways to demolish concrete structures for waste disposal and clearance. Apparent diffusion coefficients and activation energies of diffusion of radionuclides in heat-altered hardened cement paste (HCP) were determined in order to estimate the depth profile in concrete structures. Dehydration of HCP enlarged the pore size distribution, resulting in greater apparent diffusion coefficients, and activation energies of diffusion closer to those in free water.
    The total cost of decommissioning was estimated for 1) immediate dismantling scenario, 2) safe-storage scenario with various storage periods, 3) immediate dismantling followed by storage of waste packages until significant decay of radionuclides in the waste. The estimates showed that the scenario 3) is more or as cost effective as other scenarios, and may be worth considering.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), Hokkaido University, 16K06950
  • Study on the mechanisms of radiocesium sorption/desorption on soil containing waste: Effects of organic matter through experimental and MD approaches
    Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)
    01 Apr. 2012 - 31 Mar. 2015
    WATANABE Naoko; KOZAKI Tamotsu
    To gain understanding on the long-term stability of the soil waste containing radiocesium for interim storage and disposal, effects of organic matter on the interaction between clay mineral surfaces and Cs were studied. Different sorption sites on mineral surfaces, including planar and interlayer surfaces as well as edges, were assumed to model the sorption experiment results to obtain the results that each site is affected differently by the presence of organic matter in the solution phase: sorption capacity of the interlayer sites of montmorillonite decreased with the presence of humic acid, and the selectivity on the illite FES site increased with the presence of fulvic acid. In addition, molecular dynamics simulation revealed the structure of a very strong innersphere complex formed at K-mica edges.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), Hokkaido University, 24561036
  • Migration behavior of materials in clay buffer materials in geological disposal of high-level radioactive waste and migration-controlled corrosion of iron
    Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
    01 Apr. 2011 - 31 Mar. 2014
    KOZAKI Tamotsu; WATANABE Naoko; TOMIOKA Satoshi; KOZAI Naofumi
    For the safety assessment of the geological disposal, it is necessary to understand the corrosion behavior of iron in bentonite buffer material and identify important parameters to affect the corrosion. In this study, corrosion of iron and migration of ions in compacted bentonite under electrical gradient were studied. In addition, hydraulic property of sedimentary rock sample was studied by conducting hydraulic conductivity measurement and X-ray micro CT observation of the rock sample. Hydraulic conductivity measurements were also made for Fe(II)-montmorillonite to understand the effect of the alteration of bentonite on the performance as the buffer material.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Hokkaido University, 23360417