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Grasping of situation in core

 The temperature inside the PVC of each reactor is continuously low and it has been proven by measuring radioactive materials that recriticality has not occurred. Thus, fuel debris has been cooled and is in a stable condition.

 On the other hand, access to the inside of buildings is so restricted that there are technical difficulties to assess internal conditions visually.

 Therefore, in addition to proceeding with practical research while developing remote-controlled observation and measuring devices which are capable of being inserted into the PCV through a penetration for locating fuel debris in particular places and tomographic technology for nuclear reactors using muon measurement, it is necessary to develop comprehensive analysis and evaluation, taking into account data and information gathered through research on temperature measurement at sites and distribution of radioactive materials and estimates by accident progression analysis code.

The whole picture of decommissioning strategies and issues

The whole picture of decommissioning strategies and issues -grasping of situation in core-

R&D efforts

Comprehensive analysis and evaluation of fuel debris and FP status

Device/equipment development /demonstration for the full scale practical system research and measurement

Plant investigation, measurement date, and information

Efforts to understand the plant status at each of Units 1 to 3, and for fuel debris retrieval (Updated monthly, February 2019) 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, April 2019) new
Chronology (Events after the accident, in-core situation, etc.) (Updated regularly, September 2018)

Other related information

Fukushima Daiichi NPS accident background and lessons: Estimations of the accident progression at each Unit (“Why did the accident occur?” and “Accident background”) (TEPCO)
  • Accident background
  • Accident process
TEPCO Fukushima Daiichi NPS accident-related technology workshop
  • Guidance materials
  • Lecture materials