Technical Strategic Plan 2016 for Decommissioning of the Fukushima Daiichi Nuclear Power Station of Tokyo Electric Power Company Holdings, Inc. July 13, 2016 Nuclear Damage Compensation and Decommissioning Facilitation Corporation All rights reserved except for reference data. No part of this document may be reproduced, edited, adapted, transmitted, sold, published, digitalized or used in any other way that violates the Copyright Act for any purpose whatsoever without the prior written permission of Nuclear Damage Compensation and Decommissioning Facilitation Corporation. 1. Introduction ·········································································································· 1-1 2. The Strategic Plan ··································································································· 2-1 2.1 Progress toward the decommissioning of the Fukushima Daiichi NPS ······························· 2-1 2.2 Positioning and purpose of the Strategic Plan ···························································· 2-3 2.3 Basic concept of the Strategic Plan ········································································· 2-6 2.3.1. Fundamental policy ··················································································· 2-6 2.3.2. Five Guiding Principles ·············································································· 2-6 2.4 Approach to the international cooperation································································ 2-11 2.5 Overall structure of the Strategic Plan ···································································· 2-12 3. Risk reduction strategy ····························································································· 3-1 3.1 Method of reviewing the risks posed by radioactive materials ········································· 3-1 3.1.1. Terms and Definitions ················································································ 3-1 3.1.2. Risk management process ··········································································· 3-2 3.1.3. Methodology of risk analysis ········································································ 3-6 3.1.3.1 Risk metric ·················································································· 3-6 3.1.3.2 Hazard Potential ············································································ 3-6 3.1.3.3 Safety Management ········································································ 3-7 3.2 Strategy for reducing risks posed by radioactive materials ············································· 3-9 3.2.1. Risk identification ···················································································· 3-9 3.2.2. Risk analysis ·························································································· 3-11 3.2.2.1 Selection of nuclides for evaluation ···················································· 3-11 3.2.2.2 Hazard Potential ··········································································· 3-11 3.2.2.3 Safety Management ······································································· 3-12 3.2.3. Risk evaluation ······················································································· 3-12 3.2.3.1 Prioritization of risk sources ····························································· 3-12 3.2.3.2 Changes in the level of risks over one year ············································ 3-14 3.2.4. Risk treatment ························································································ 3-15 3.2.4.1 Basic strategy for risk reduction ························································· 3-15 3.2.4.2 Issues in risk treatment ··································································· 3-16 3.3 Steady promotion of decommissioning project ·························································· 3-18 3.3.1. Project risk management ············································································ 3-18 3.3.2. Relation with the society ············································································ 3-20 4. Strategic plan for fuel debris retrieval ············································································ 4-1 4.1 Study plan for fuel debris retrieval (risk reduction) ······················································· 4-1 4.1.1 Approaches to the study on fuel debris retrieval ··················································· 4-5 4.1.2 Role-sharing among related organizations ························································· 4-12 4.2 PCV inspection strategy and latest information ··························································· 4-13 4.2.1 Basic concept of internal PCV condition analysis ················································ 4-13 4.2.2 Maintaining management of stable condition ····················································· 4-18 4.2.3 Current survey status·················································································· 4-20 4.2.3.1 Current status and evaluation of investigation of conditions inside the actual reactor4-21 4.2.3.1.1 PCV/RPV internal survey ····················································· 4-21 4.2.3.1.2 Muon detection ································································· 4-23 4.2.3.2 Estimation by severe accident analysis codes ··········································· 4-24 4.2.3.3 Estimation based on knowledge and experiments ······································ 4-27 4.2.3.3.1 Engineering estimation based on the plant data ··························· 4-28 4.2.3.3.2 Estimation of fuel debris properties based simulated fuel debris experiments ··································································· 4-29 4.2.4 Comprehensive evaluation for the internal PCV condition and future actions ··············· 4-31 4.2.4.1 Summary of comprehensive analysis and evaluation of internal PCV condition ·· 4-31 4.2.4.2 Issues on the internal PCV condition analysis and future actions ···················· 4-34 4.3 FS of fuel debris retrieval method ··········································································· 4-37 4.3.1 The selection of fuel debris retrieval methods and their features ······························· 4-37 4.3.2 Approach to key issues on fuel debris retrieval ··················································· 4-46 4.3.2.1 Securing the structural integrity of the PCV and R/B ································· 4-48 4.3.2.2 Criticality control ··········································································· 4-54 4.3.2.3 Maintaining the cooling function ························································· 4-62 4.3.2.4 Ensuring containment function ··························································· 4-66 4.3.2.4.1 Concept of ensuring containment functions ································ 4-66 4.3.2.4.2 Construction of boundary (e.g. PCV repair) ······························· 4-71 4.3.2.5 Reduction of worker’s exposure during operation ····································· 4-79 4.3.2.5.1 Decontamination of the inside of the R/B ·································· 4-80 4.3.2.5.2 Exposure reduction by shielding when retrieving fuel debris ··········· 4-86 4.3.2.6 Ensuring work safety ······································································· 4-89 4.3.2.7 Establishment of the access route to the fuel debris ··································· 4-92 4.3.2.8 Development of the fuel debris retrieval equipment and devices ·················· 4-100 4.3.2.9 Establishment of the system equipment and working areas ························ 4-105 4.3.2.10 Towards the detailed study based on the work steps of each method ············ 4-107 4.4 Study of the treatment for the retrieved fuel debris toward stable storage··························· 4-112 4.4.1 Establishment of the system for fuel debris collection, transport and storage ·············· 4-112 4.4.2 Study on safeguards approach for fuel debris ··················································· 4-117 4.5 Studies to determine the approaches to the retrieval method for each Unit ························· 4-118 4.5.1 Study status of the internal PCV conditions analysis ·········································· 4-118 4.5.2 Overview of the approaches to the study on the fuel debris retrieval method ·············· 4-119 4.5.3 Study on access direction to the fuel debris ····················································· 4-122 4.5.4 Feasibility study of retrieval for each fuel debris location ···································· 4-123 4.5.5 Studies on decision on approaches to retrieval method ········································ 4-124 4.5.6 Estimative index and perspective of evaluation based on the Five Guiding Principles ··· 4-126 5. Strategic plan for waste management ············································································ 5-1 5.1 Study policy on the strategic plan for waste management ·············································· 5-1 5.2 International safety principles on radioactive waste management ····································· 5-2 5.2.1. Principles for ensuring the safety of radioactive waste disposal ······························· 5-2 5.2.2. Examples of application on safety principles for radioactive waste disposal ················ 5-5 5.2.3. Appropriate radioactive waste management ······················································ 5-6 5.3 Assessments and issues on the action status