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Survey at Fukushima No. 1 reactor container halted.

Fukushima No. 1 nuclear plant in Fukushima Prefecture, on Aug. 19

Jan 12, 2022

Tokyo Electric Power Company Holdings Inc. halted its investigation of the inside of the containment vessel of the No. 1 reactor at its stricken Fukushima No. 1 nuclear power plant on Wednesday.

The move came after an issue was found during preparation work for the display of data such as radiation levels from dosimeters inside underwater robots to be used in the survey. The preparations began at noon the same day and were halted around two hours later.

Tepco said that it will resume the survey once measures to resolve the issue are taken.

In the survey, which will continue until around August, Tepco aims to take pictures of melted nuclear fuel debris and other deposits using six types of underwater robots to record their locations and thickness in water that has accumulated at the bottom of the containment vessel.

It will also try to collect deposit samples and take pictures of the inside of the base that supports the reactor pressure vessel. The information obtained in the survey will be used for studies on ways to remove the debris.

The nuclear fuel at the No. 1 reactor’s core is believed to have melted and mostly fallen inside the containment vessel during the triple meltdown disaster at the plant, which was hit by a huge earthquake and tsunami on March 11, 2011.

In its survey of March 2017, Tepco failed to find nuclear fuel debris at the No. 1 reactor, leaving the reactor’s detailed situation unknown, in contrast to the No. 2 and No. 3 reactors, where melted fuel debris was successfully photographed.

https://www.japantimes.co.jp/news/2022/01/12/national/tepco-fukushima-survey-halted/

January 14, 2022 Posted by | Fuk 2022 | , , , | 1 Comment

TEPCO to slice dangerous chimney at Fukushima plant

chimney reactors 1 & 2 10 may 2019.jpgA chimney for both the No. 1 and No. 2 reactors remains unrepaired at the Fukushima No. 1 nuclear power plant. At left is the No. 1 reactor building.

May 10, 2019
Tokyo Electric Power Co. plans to start work on May 20 to dismantle a 120-meter-tall, highly contaminated chimney that could collapse at the crippled Fukushima No. 1 nuclear power plant.
It will be the first highly radiated facility at the plant to be taken apart, the company said May 9.
The stack, with a diameter of 3.2 meters, was used for both the No. 1 and No. 2 reactors. TEPCO plans to remove the upper half of the chimney within this year to prevent the structure from collapsing.
The dismantling work will be conducted by remote control because the radiation level around the base of the chimney is the highest among all outdoor areas of the plant. Exposure to radiation at the base can cause death in several hours.
After the Great East Japan Earthquake and tsunami struck in March 2011, pressure increased in the containment vessel of the No. 1 reactor. Vapors with radioactive substances were sent through the chimney to the outside.
TEPCO also found fractures in steel poles supporting the chimney. The damage was likely caused by a hydrogen explosion at the No. 1 reactor building when the nuclear disaster was unfolding.
Since then, the chimney has been left unrepaired because of the high radiation levels.
Immediately after the nuclear accident, a radiation level exceeding 10 sieverts per hour was observed around the base of the chimney. In a survey conducted in 2015, a radiation level of 2 sieverts per hour was detected there.
TEPCO will use a large crane that will hold special equipment to cut the chimney in round slices from the top.
The company set up a remote control room in a large remodeled bus about 200 meters from the chimney. Workers will operate the special cutting equipment while watching footage from 160 video cameras.
http://www.asahi.com/ajw/articles/AJ201905100045.html

May 15, 2019 Posted by | fukushima 2019 | , , , | Leave a comment