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Ensuring safety for fuel debris retrieval (3) (Construction of containment function)

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

Ongoing projects

Development of Closed Circulation Systems for Water Inside PCV (Project of Decommissioning and Contaminated Water Management)
Summary

We develop technologies of access, connection and repair in PCV while securing containment function in PCV, in order to build the closed circulation systems for water inside PCV necessary for ensuring safety of retrieval construction of fuel debris.

Action items
  1. Arrangement of technical specifications of access, connection and repair technologies in PCV/study on working plan/making and update of development plan
  2. Development/verification of elemental technologies of access/connection in PCV
  3. Full-scale verification of access/connection technologies in PCV
Implementing organizations

Implemented by IRID.

Implementation plan

Targeted process: Development of closed circulation systems for water inside PCV

Source: FY 2019 Research and Development Plan for Decommissioning
    (METI, Secretariat of the Team for Countermeasures for Decommissioning and Contaminated Water Treatment (February 28, 2019))
(PDF page 13)

Results & performance by fiscal year
  • FY 2018
Torus room investigation (TEPCO)
  • Fukushima Daiichi NPS Unit 1 torus room inspection (first day) (February 20, 2013) (TEPCO)
  • Fukushima Daiichi NPS Unit 2 torus room inspection drilling work results (March 26, 2013) (TEPCO)
  • Fukushima Daiichi NPS Unit 2 torus room inspection drilling work results (January 28, 2013) (TEPCO)
Bent pipe inspection (TEPCO)
  • Fukushima Daiichi NPS, Unit 1 bent pipe lower portion periphery inspection results (first day) (November 13, 2013) (TEPCO)
  • Fukushima Daiichi NPS Unit 2 bent pipe lower portion periphery inspection results (March 15, 2013) (TEPCO)
  • Fukushima Daiichi NPS Unit 2 bent pipe lower portion periphery inspection results (March 14, 2013) (TEPCO)
  • Fukushima Daiichi NPS Unit 2 bent pipe lower portion periphery inspection results (March 6, 2013) (TEPCO)
  • Fukushima Daiichi NPS Unit 2 bent pipe lower portion periphery inspection results (March 5, 2013) (TEPCO)
  • Fukushima Daiichi NPS Unit 2 bent pipe lower portion periphery inspection results (December 11, 2012) (TEPCO)
S/C inspection (TEPCO)

Completed projects

Development of Repair Technology for Leakage Sections in PCV (Project of Decommissioning and Contaminated Water Management)
Summary

We developed technology to build and maintain boundaries for repair and water leakage stoppage of all PCV elements, including reinforcement technology development for suppression chamber supports, examining circulative cooling systems, water leakage stoppage technology for bent pipes, water leakage stoppage technology development for seals, water leakage stoppage technology development for pipe bellows, building boundaries for PCV connection pipes, water leakage stoppage technology for torus room wall pipe penetrations, and D/W shell repair technology. We also created plans for PCV water filling.

Action items
  1. Process study/planning of filling water up to PCV
  2. Development of technique for repairing bottom part of PCV
    • Technology for reinforcement and water stoppage in S/C and bent pipes
    • Technology for water stoppage due to laying vacuum break line
    • Connecting piping boundary construction technology
    • Development of water stoppage technology for torus room walls with pipe penetration
  3. Development of technique for repairing upper part of PCV
    • Water stoppage technology at seals (equipment hatches)
    • Pipe bellows repair technology
    • D/W shell repair technology
  4. Conceptual study of feasibility for practical application of repair method
Implementing organizations

Implemented by IRID.

Implementation plan

Targeted process: Development of repair technology for leakage sections in PCV

Source: Progress status of R&D project and direction for next period
    (METI, Secretariat of the Team for Countermeasures for Decommissioning and Contaminated Water Treatment (February 23, 2017))
(PDF page 15)

Results & performance by fiscal year
  • FY 2017
  • FY 2016
  • FY 2015
  • FY 2014
  • FY 2013
  • FY 2012
Results & performance for individual projects, etc. (Archives)

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Full-scale Test of Repair Technology for Leakage Sections in PCV (Project of Decommissioning and Contaminated Water Management)
Summary

We used mockup facilities to conduct full-scale tests of machinery and equipment for repair of lower PCV, to verify and assess the applicability and feasibility at Fukushima Daiichi NPS. Also, in order to perform these full-scale tests, we utilized full-size test models that simulate the lower PCV (suppression chamber, bent pipes, etc.), created hypothetical work procedures (drafts) based on plant processes, and confirmed the procedures using that test platform to verify the appropriateness of those procedures. We further took samples of reinforcing material and water leakage stoppage placed on test body through core boring, etc., and performed analysis evaluation of material performance, etc. Then we studied comparisons of the machine operations in full-scale tests to VR system operations, aiming to establish effective and efficient methods for using the VR system.

Action items
  1. Full-scale test of repair and water sealing
  2. Integrity check for reinforcing materials after testing and water seal materials
  3. Maintenance of VR data for preliminary simulation test
Implementing organizations

Implemented by IRID.

Implementation plan

Targeted process: Full-scale test of repair technology for leakage sections in PCV

Source: Progress status of R&D project and direction for next period
    (METI, Secretariat of the Team for Countermeasures for Decommissioning and Contaminated Water Treatment (February 23, 2017))
(PDF page 16)

Results & performance by fiscal year
  • FY 2017
  • FY 2016
  • FY 2015
  • FY 2014
Results & performance for individual projects, etc. (Archives)

Switch button

  • Torus room investigation
  • Results of verification tests of torus room wall inspection equipment in Unit 2 that are in development in the R&D “Development of technologies for repair and identification of leakage points inside the PCV” (October 2015) (TEPCO)
  • S/C inspection
  • Fukushima Daiichi NPS Unit 1 S/C (pressure control room) upper portion inspection results (exterior West and South sides) (May 30, 2014) (TEPCO)

R&D efforts (related basic and generic research)

Repair technology development (Decommissioning Basic Research: Human resource development program at Tohoku University - Basic research into reliability maintenance of PCV and buildings, etc., and waste processing and disposal, and core human resource development program for decommissioning

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 monthly, June 10, 2020) new

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

Plant-related parameters
Fukushima Daiichi NPS survey map
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
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 (PDFWord file)
Collection of links to data on in-core situation (Updated monthly, January 8, 2020) new
Chronology (Events after the accident, in-core situation, etc.) (Updated regularly, September 2018)

Other related information

<Updated regularly>