Information Portal for the Research and Development
for the Fukushima Daiichi Decommissioning

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Ensuring safety for fuel debris retrieval (2) (Criticality safety control)

R&D efforts (Application development linked to plant applications and actual use)

Completed projects

Development of Criticality Control Technologies of Fuel Debris (Project of Decommissioning and Contaminated Water Management)

Summary

We review criticality scenario, potential evaluation of criticality and behavior evaluation at the time of criticality arrival every units reflecting the most recent information on comprehensive analysis/evaluation results of conditions in the reactor. Also, we develop, design, and build detection systems to monitor fuel debris sub-criticality by monitoring fission products for the purpose of stratified criticality control, and perform feasibility tests and confirm operability in a highly irradiated environment. And then in order to prevent criticality during fuel debris retrieval, we study development of neutron absorbents and operating methods to use them.

Action items

1. Establishment of criticality evaluation technique
   • Study of criticality control method
   • Study of criticality control and criticality scenario
2. Development of criticality control technology
   • Sub-criticality monitoring methods
   • Re-criticality detection technologies
   • Criticality prevention technologies

Implementation organization

Implemented by IRID.

Implementation plan

Source: Progress status of R&D projects and direction for next period
　　　　(METI, Secretariat of the Team for Countermeasures for Decommissioning and Contaminated Water Treatment (February 23, 2017)) (PDF page 14)

Results & performance by fiscal year

• FY 2017

• Final report (Development of technology for controlling fuel debris criticality (March 2018)) (IRID) (PDF)
• Status of progress at the end of February 2018 (METI, Secretariat of the Team for Countermeasures for Decommissioning and Contaminated Water Treatment (March 1, 2018)) (PDF page 28)
• Development of "Critical Approach Monitoring Method" Using Kyoto University Critical Assembly (KUCA) (June 21, 2017) (IRID)

• FY 2016

• Interim report (Development of technology for controlling fuel debris criticality (April 2017)) (IRID) (PDF)
• Progress status as of the end of February 2017 (METI, Secretariat of the Team for Countermeasures for Decommissioning and Contaminated Water Treatment (February 25, 2017)) (PDF page 24)

• FY2015

• Completion report (Development of technology for controlling fuel debris criticality (March 2016)) (IRID) (PDF)
• Progress status as of the end of February 2016 (METI, Secretariat of the Team for Countermeasures for Decommissioning and Contaminated Water Treatment (February 25, 2016)) (PDF page 42)

• FY 2014

• Summary of results (METI, Secretariat of the Team for Countermeasures for Decommissioning and Contaminated Water Treatment (February 26 2015)) (PDF page 7)

• FY 2013

• Development of technology for controlling fuel debris criticality (July 31, 2014) (IRID) (PDF)

• FY 2012

• Summary of results (METI, Secretariat of the Council for the Decommissioning of TEPCO’s Fukushima Daiichi (March 28, 2013)) (PDF page 72)

Results & performance for individual projects, etc. (Archives)

R&D efforts (related basic and generic research)

Recriticality accident analysis during debris retrieval (Decommissioning Basic Research: Human resource development program at Tokyo Institute of Technology - Advancements in skilled human resource development for and basic research on decommissioning engineering) (PDF)

Measures to ensure sub-criticality during debris retrieval (Decommissioning Basic Research: Human resource development program at Tokyo City University - Advancements in skilled human resource development for and basic research on decommissioning engineering) (PDF)

Plant investigation, measurement data, and information

Efforts to understand the plant status at each of Units 1 to 3, and for fuel debris retrieval (Updated December 4, 2024)

(METI, Secretariat of the Team for Countermeasures for Decommissioning and Contaminated Water Treatment)

• Current Status of Fukushima Daiichi NPS (As of September 26, 2024)

Plant-related parameters

• Outline of the plant (TEPCO)
• Newest data (water level, pressure, temperature, etc.) (TEPCO)

• Plant-related parameters (Summary table) (PDF)
• Temperature parameters (Chart) Real-time data

• Unit 1 Temperature in the RPV (PDF)
• Unit 1 Temperature in the PCV (PDF)
• Unit 2 Temperature in the RPV (PDF)
• Unit 2 Temperature in the PCV (PDF)
• Unit 3 Temperature in the RPV (PDF)
• Unit 3 Temperature in the PCV (PDF)

• Fukushima Daiichi NPS plant data collected at the time of the accident (TEPCO)
• The Great East Japan Earthquake and Current Status of Nuclear Power Station(TEPCO)
• Outline of the plant (IRID) (PDF) only Japanese page

Fukushima Daiichi NPS survey map

• Inside reactor buildings, etc. (TEPCO)

Common data presented by Benchmark Study of the Accident at the Fukushima Daiichi Nuclear Power Plant (BSAF) related to accident progression analysis according to OECD/NEA

• Plant basic data (reactor core, fuel, control rods, RPV, PCV, circulation water system, main steam system, etc.) (PDF)

Information Portal for the Fukushima Daiichi Accident Analysis and Decommissioning Activities

• Information Portal for the Fukushima Daiichi Accident Analysis and Decommissioning Activities

Collection of figures of data on in-core situation (Updated regularly, August 2018)

• Figures of temperature, dose rate, amount of water injection, etc. in each Unit (PDF・Word file)

Collection of links to data on in-core situation ( January 8, 2020) new

• Grasping of fuel debris Only Japanese(PDF)
• Stability of fuel debris Only Japanese(PDF)
• Operation safety Only Japanese(PDF)
• Retrieval of fuel debris and others Only Japanese(PDF)

Chronology (Events after the accident, in-core situation, etc.) (Updated regularly, September 2018)

• Chronology of Fukushima Daiichi NPS (Excel File)

Other related information

＜Updated regularly＞