JAPAN ATOMIC INDUSTRIAL FORUM, INC.

for Japanese

ATOMS in JAPAN

2 August, 2016

Fuel Debris at Fukushima Daiichi-2 Mostly Found at Bottom of Reactor Pressure Vessel

On July 28, the Tokyo Electric Power Co. (TEPCO) released its evaluation of the results of an examination of fuel debris in Unit 2 at the Fukushima Daiichi Nuclear Power Plants, carried out using cosmic-ray muon measurement technology. Most of the spent fuel debris—fuel that had melted in the accident and resolidified—appears to be at the bottom of the reactor pressure vessel (RPV) of Unit 2.

TEPCO conducted the examination in a joint project with the High Energy Accelerator Research Organization (abbreviated KEK, after the Japanese “Kō-enerugii Kasoku-ki Kenkyū Kikō”). Two panels (plastic scintillators) that have been installed inside the measurement device (see photo)—itself about one cubic meter in size—detect the scattering of muon particles.

The distribution of materials is calculated based on muon transmittance. The effectiveness of the method had already been established in studies that took place at Unit 1. At Unit 2, the examination took place from March to July 2016 to identify the shadows of high-density materials believed to be fuel debris at the bottom of the RPV.

Despite some uncertainties in the range of a few tens of tons, some 20 to 50 tons remain in Unit 2’s reactor core (inside the shroud), based on calculations of the amount of materials at the bottom. That compares with about 160 tons of fuel assemblies and about 15 tons of control rods in the core before the accident.

Also, about 160 tons remains at the bottom of Unit 2’s RPV, in contrast to 35 tons before the accident. That indicates that most of the fuel debris has collected at the bottom of the RPV. According to the national medium-range to long-term roadmap toward decommissioning, TEPCO will decide on a method of removal of fuel debris during the first half of fiscal 2018 (April to September 2018).

On July 28, TEPCO also released its “Management Plan for Sustainable Business,” in light of changes in the business environment. According to that, the power company will try to build a system integrating all national resources to carry out the decommissioning of Fukushima Daiichi NPPs steadily. Cooperation will be particularly strengthened with the Japan Atomic Power Company (JAPC), among other organizations.

Comment

This site uses Akismet to reduce spam. Learn how your comment data is processed.

SNS facebooktwitter

NPPs Map

Video

Grossi on Fukushima: Marking a Decade Since the Accident

10 March, 2021
Grossi on Fukushima: Marking a Decade Since the Accident04:11

Recent News

18 November, 2021
METI Minister Speaks to IAEA International Conference on Decade of Progress Since Fukushima Daiichi Accident
15 November, 2021
Nuclear Energy’s Contribution to Achieving SDGs
8 November, 2021
COP26: Prime Minister Kishida Announces Additional Contribution of USD10 Billion for Climate Change Measures
30 October, 2021
Reelection of Suttsu Mayor Means Literature Investigation for HLW Disposal Will Continue
21 October, 2021
Kishida Makes First Visit to Fukushima Since Becoming Prime Minister
15 October, 2021
LDP Adds SMR Development and Nuclear Fusion to NPP Restarts in Its Policy Manifesto
7 October, 2021
Kishida Administration Inaugurated, with New METI Minister Hagiuda Holding Press Conference on Taking Office
6 October, 2021
IAEA Holds 65th General Conference in Vienna, with Japanese Minister of State for Science and Technology Delivering Statement in the General Debate
30 September, 2021
JAEC Releases 2020 White Paper on Nuclear Energy
17 September, 2021
NRA Permits Shimane-2 under New Regulatory Standards
14 September, 2021
IAEA Deputy Director General Evrard Visits Japan in Advance of Safety Review of ALPS-treated Water
1 September, 2021
Evaluation Report Issued by IAEA’s Review Mission to Fukushima Daiichi: First Visit since 2018
24 August, 2021
METI and IAEA Agree on Further Review Missions to Fukushima Daiichi
4 August, 2021
JAEA Restarts High-Temperature Engineering Test Reactor “HTTR”
2 August, 2021
Information about Fukushima Daiichi NPS Water Treatment
28 July, 2021
METI’s Committee Shows Rough Draft of Next Strategic Energy Plan
2 July, 2021
Mihama-3 Restarted After Decade-long Hiatus: First Restart in Japan of a Reactor Operating Beyond 40 Years
28 June, 2021
Mihama-3 Restarts after Decade-long Hiatus
25 June, 2021
New Canada-Japan Partnership Supports Greater Collaboration to Meet Climate Change Objectives and Net-zero Goals
24 June, 2021
METI Issues New Green Growth Strategy Through Achieving Carbon Neutrality
▲TOP