27 Juillet 2018
July 27, 2018
TEPCO eyes 1st contact with fuel debris in damaged nuke reactor from Oct.
TOKYO -- Tokyo Electric Power Co. (TEPCO) will directly touch melted fuel debris inside a damaged reactor at the Fukushima No. 1 Nuclear Power Plant for the first time sometime from October onward, the utility and the government announced on July 26.
The company will insert a pipe into the containment vessel of the plant's No. 2 reactor and use a device at its tip to confirm the hardness and other properties of the debris, before retrieving a small amount from that reactor and the No. 1 reactor in fiscal 2019. Full-scale removal of debris is scheduled to start in 2021, likely at the No. 2 reactor, where probes have been the most extensive.
The pipe to be used to make direct contact with the debris will be an improved version of one equipped with a camera that was used to film inside the No. 2 reactor's containment vessel in January. Besides checking the hardness of the debris, the company will also examine whether it can be moved. It will incorporate the results of its test removal of debris in deciding on a method for full-scale removal.
"We don't know what the debris will be like. We will examine it step by step as we look ahead to its removal," Akira Ono, president of Fukushima Daiichi Decontamination & Decommissioning Engineering Co. said at a news conference.
Meanwhile, TEPCO has announced that in November it will start to remove 566 nuclear fuel rods which have been kept in the No. 3 reactor's fuel pool. It will aim to complete the removal of these fuel rods in 2020.
(Japanese original by Toshiyuki Suzuki, Science & Environment News Department)
July 25, 2018
Gov't, TEPCO consider starting removal of debris from 2nd reactor at Fukushima nuke plant
TOKYO -- The government and Tokyo Electric Power Co. (TEPCO) are considering starting the removal of molten nuclear fuel from the No. 2 reactor of the Fukushima No. 1 Nuclear Power Plant, people familiar with the matter have told the Mainichi Shimbun.
Three of the four reactors at the plant in the northern Japanese prefecture of Fukushima suffered core meltdowns after the reactors' cooling systems shut down due to tsunami triggered by the Great East Japan Earthquake of March 2011.
According to the sources, an on-site inspection of molten fuel debris inside the reactor's containment vessel using remote control equipment will be conducted this fiscal year. Data from the test, such as the hardness of the debris and whether it is movable, will be used to develop equipment to remove and store the highly radioactive materials.
Under the road map for decommissioning the power plant revised in September last year, the government and TEPCO are to decide on a reactor on which to start debris removal and determine how to carry out the procedure by March 2020, the end of next fiscal year. Actual removal is scheduled to begin in 2021.
In January of this year, the government and TEPCO managed to insert a pipe with a camera into the No. 2 reactor's containment vessel and captured the image of gravel- or clay-like deposits believed to be fuel debris on the floor.
According to the people familiar with the matter, the government and TEPCO have judged that it is necessary to further examine the conditions of the No. 2 reactor as a possible starting point for fuel debris removal, since inspections needed for such an operation have progressed further on the No. 2 unit more than on the other two reactors that suffered core meltdowns in 2011.
The government and TEPCO will carry out the new probe in the fall or later of this year by inserting a camera-equipped pipe attached with a device capable of directly touching the debris, which will gather data on the reactor's current conditions. The debris is not taken out of the containment vessel at any point of this survey. In the next fiscal year starting April 2019, they will consider examining wider areas inside the containment vessel and recovering a small sample of molten fuel for analysis ahead of full-fledged extraction in 2021.
As for the other reactors, the No. 3 unit has water inside the containment vessel, the removal of which is difficult, although images of what appeared to be fuel debris were captured inside the reactor in July 2017. The No. 1 reactor, meanwhile, will receive another probe to determine the existence of molten fuel inside because an inspection carried out in March last year failed to spot any debris.
TEPCO will shortly submit a plan for the examination of the No. 1 and No. 2 reactors' interior for fiscal 2019 and later to the Nuclear Regulation Authority.
(Japanese original by Toshiyuki Suzuki and Ei Okada, Science & Environment News Department)