Fukushima Daiichi Unit 2 Spent Fuel Removal Process
December 23, 2021
TEPCO has been progressing with the preparation work for the eventual removal of the spent fuel from unit 2 at Fukushima Daiichi. New details of the fuel removal process have also been released.
Spent fuel removal is scheduled to begin in 2024 and be completed by 2026. Further decontamination work inside is underway as is work outside the building to remove debris and prepare the ground for the spent fuel removal building. The control room on the refueling floor is slated for removal to make way for the opening between the refueling floor and the new spent fuel removal building to be constructed.
Decontamination work on the refueling floor is underway. Starting in January 2022 shielding materials will be installed on the refueling floor.
Shielding appears to be slated to go along certain walls and over the reactor well area. The existing spent fuel crane will be moved over the reactor well to make room for the new fuel handling crane.
Spent fuel removal building progress as of December 2021
The floorplan (below) shows a tall shielding system to be installed around the spent fuel pool area, isolating it from the reactor well. This will act as a shielded access hallway for workers to enter the area. The floorplan also shows the spent fuel removal building where it will be installed adjacent to the spent fuel pool.
The shielding locations are shown in green in the diagram (below).
Ground foundation work is underway near unit 2 for the spent fuel removal building. This work is being done with remote equipment due to the radiation levels between units 2 and 3. The levels are still considered too hazardous for human workers a decade after the initial disaster.
The original TEPCO report in Japanese can be found here.
All original images credit, TEPCO.
Work begins to remove spent MOX fuel at Ikata nuclear plant in Ehime
A pool containing used mixed-oxide fuel that was removed from reactor No. 3 of the Ikata nuclear power plant in Ehime Prefecture on Tuesday
January 15, 2020
MATSUYAMA, EHIME PREF. – Shikoku Electric Power Co. has started removing nuclear fuel, including spent mixed-oxide (MOX) fuel, from a nuclear reactor in western Japan.
The work at the No. 3 reactor at the company’s Ikata nuclear plant in Ehime Prefecture, which began late Monday night, is the first time used MOX fuel, a blend of plutonium extracted from spent nuclear fuel and uranium, has been removed from any commercial nuclear power plant in Japan excluding tests.
A total of 157 fuel assemblies, including 16 MOX fuel assemblies, will be removed. The work is expected to continue through Thursday.
The work was originally scheduled to start at 12 a.m. Monday, but was delayed as the firm was investigating an incident that occurred during preparation work Sunday, in which a control rod was removed from the reactor by mistake and was re-inserted seven hours later.
Japan is not equipped to reprocess spent MOX fuel. Shikoku Electric, therefore, will store the MOX fuel at the power plant for the time being.
In March, five new MOX fuel assemblies will be installed in the reactor.
Control rod mistakenly removed from Ikata reactor in Ehime during maintenance
Reactor No. 3 at the Ikata nuclear power plant in Ehime Prefecture in April 2018
Jan 13, 2020
MATSUYAMA, EHIME PREF. – During recent maintenance work at the Ikata nuclear power plant that was to include the country’s first removal of spent mixed-oxide (MOX) fuel following full-scale “pluthermal” power generation, a control rod was removed from the reactor by mistake, according to Shikoku Electric Power Co.
The incident involving reactor No. 3 at the plant in Ikata, Ehime Prefecture, caused no loss of control of the nuclear reaction in the unit and no radioactive materials were released, the company said Sunday. The reactor has been shut down since Dec. 26 to perform the maintenance work.
To remove fuel assemblies during the inspection, it was necessary to raise the apparatus at the top of the reactor from which fuel is suspended. While raising the apparatus, a control rod was also lifted out of the reactor along with the fuel assemblies, Shikoku Electric stated.
Control rods are used to suppress nuclear fission, and are inserted in order to halt a nuclear reactor. According to the power company, for fission to be allowed to occur within the reactor, it is necessary to adjust the concentration of boron within the reactor coolant in addition to removing the control rods.
According to Shikoku Electric and prefectural authorities, one of the 48 control rods in the unit was lifted out of the reactor containment vessel accidentally at around 1:20 p.m. Sunday together with the upper part of the apparatus that holds fuel assemblies in place from above and below.
As the apparatus was lifted by crane, a worker noticed that the control rod had also been raised out of the containment vessel. Around seven hours later, the control rod was reinserted into the reactor.
Because the crane’s weight sensor had shown a value typically seen when the control rods are disconnected, the control rods were determined to have been detached from the apparatus and the crane was raised, Shikoku Electric said.
The company had planned to start removing the spent MOX fuel assemblies, which contain a blend of plutonium extracted from spent nuclear fuel and uranium, from the reactor at 12 a.m. Monday. The work is now expected to be delayed due to the company’s investigation into the incident involving the control rod.
Shikoku Electric also announced last Tuesday that in October 2017 it mistakenly conducted an inspection of an emergency air supply filter in the main control room of reactor No. 3 without removing all the fuel from the reactor as stipulated in the safety regulations.
The operation to extract the MOX fuel assemblies is the first such removal to be performed at any commercial nuclear power plant in Japan since an initiative on pluthermal power generation using the mixed fuel was announced in 1997, according to Shikoku Electric.
The government and power firms are promoting pluthermal power generation as part of the nuclear fuel cycle featuring the extraction of plutonium from spent nuclear fuel for reuse. Shikoku Electric started pluthermal power generation in 2010 using 16 MOX fuel assemblies installed in the Ikata No. 3 reactor.
The company had been planning to remove all of them during the reactor maintenance, which is to continue through April 27. The firm will consider reusing the spent MOX fuel, which is expected to be stored at the power plant for the foreseeable future due to a lack of reprocessing facilities in this country.
Spent MOX fuel to be removed from Ikata nuke plant No. 3 reactor in January
This April 2, 2018 file photo shows the No. 3 reactor at the Ikata nuclear power plant in Ehime Prefecture, western Japan
December 26, 2019
MATSUYAMA, Japan (Kyodo) — A reactor at a nuclear power plant in Ehime Prefecture, western Japan, was shut down Thursday in preparation for the removal of spent mixed oxide fuel, a first in the country.
Shikoku Electric Power Co. plans to take out 37 spent fuel rods, 16 of which are MOX, from the Ikata plant’s No. 3 unit in January.
The utility will load five new MOX fuel rods, as well as replace the reactor’s control unit, before restarting it in late March and resuming commercial operation in late April.
MOX is made using recycled plutonium and uranium and tends to run hotter than the low-enriched uranium more widely used in thermal reactors such as the No. 3 unit.
Shikoku Electric has said it will temporarily store the spent MOX in a cooling pool within the Ikata plant, but as Japan currently does not have the necessary reprocessing facilities, it is unclear where the fuel will end up.
https://mainichi.jp/english/articles/20191226/p2g/00m/0dm/038000c
TEPCO Opens Up Space in Common Pool at Fukushima Daiichi to Receive Spent Fuel from Unit 3
Construction of a New Cover Building Installation for Spent Fuel Removal at Unit 3
This installation will enable robotic removal of spent fuel removal to begin at Fukushima Daiichi Unit 3. Plans to remove this fuel have been complicated by high radiation levels.
To install the cover building’s cylindrical portion workers will have to enter the area to manually bolt the cover to the deck structure.
Installation of the “stopper” by a crane near the spent fuel pool began on January 17 as the first step to construct a new roof for the Unit 3 spent fuel removal. Over the pool some additional structural equipment has also been installed.
Tepco will proceed with the roof construction toward eventual fuel removal with safety as a top priority.
Source : http://www.tepco.co.jp/en/nu/fukushima-np/handouts/2017/images/handouts_170117_01-e.pdf
Debris Removal at Reactor # 3 Delayed, but Arrival of the First Elements of the New Building for its Spent Fuel Removal
Transportation of the supporting part of a new roof for the Unit 3 fuel removal at Fukushima Daiichi Nuclear Power Station
The clearing of debris from reactor # 3 is delayed, delaying the construction of the new building to remove spent fuel from the pool. The debris removal was to be done in order to build a new workshop to remove the fuels from the pool.
The removal of the spent fuel should have started in January 2018. In the beginning, TEPCo was to start in 2015. We do not know their new schedule yet.
On the other hand, TEPCO communicated on the arrival of the first elements of the new building, with photos and video.
The dose rates on the site are here. There is up to 2.6 mSv / h in the vicinity of reactor No.3.
Links from TEPCO:
Photos of the new building
Click to access handouts_161220_01-e.pdf
Video
http://photo.tepco.co.jp/en/date/2016/201612-e/161220-01e.html
Dose rates in Reactor 3 vicinity
http://www.tepco.co.jp/en/nu/fukushima-np/f1/surveymap/images/f1-sv-20161219-e.pdf
Fuel removal at Fukushima reactor again faces delay
Steel frames are transported at the Fukushima No. 1 nuclear power plant on Dec. 20 to prepare for work to retrieve spent nuclear fuel from the storage pool of the damaged No. 3 reactor building.
Work to retrieve spent nuclear fuel in the No. 3 reactor building storage pool of the crippled Fukushima No. 1 nuclear power plant will again be postponed due to a delay in clearing radioactive debris at the site.
TEPCO planned to begin removing 566 spent nuclear fuel assemblies in the storage pool in January 2018. However, the government and the plant operator, Tokyo Electric Power Co., decided on the postponement, sources said on Dec. 22. They will decide on a new timetable in a few weeks.
The work was initially scheduled for fiscal 2015, but had been pushed back because of high radiation readings in and around the No. 3 reactor building. The building was heavily damaged by a hydrogen explosion in the days following the disaster, triggered by the 2011 Great East Japan Earthquake and tsunami.
TEPCO had attempted to lower radiation levels by clearing the radioactive debris remaining at the site.
But the clearing work took longer than expected due to contamination being more widespread than previously thought, forcing TEPCO and the government to again put off the retrieval.
Radiation levels have now dropped as almost all of wreckage at the site has been cleared, TEPCO said. The government and TEPCO have said fuel retrieval at the No. 1 and No. 2 reactor buildings will start in fiscal 2020 or later.
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