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Fukushima Daiichi Nuclear Power Plant, work to remove contaminated pipes suspended again due to detection of high radiation dose at level of “death by exposure for several hours

A high radiation dose of 3 sievert per hour was detected inside the cut surface at the left end of a 12-meter pipe that was cut by equipment at the Fukushima Daiichi Nuclear Power Plant on May 23.

May 27, 2022
 The removal work of pipes contaminated with high levels of radioactive materials between Fukushima Daiichi Nuclear Power Plant Units 1 and 2, which had been resumed by Tokyo Electric Power Co. for the first time in two months, was suspended again after extremely high radiation levels of 3 sieverts (3000 millisieverts) per hour were detected in the first cut pipe on May 23. The second disconnection scheduled for the 26th was cancelled. TEPCO will take time to reconsider the cutting method and measures to control workers’ exposure.
 The radiation dose of 3 sievert per hour is high enough to cause death if a person is exposed to radiation for several hours. According to TEPCO, workers who measured the dose inside the cut surface of the pipes were exposed to a maximum of 0.41 millisieverts, which did not exceed the exposure limit that had been planned in advance.
 Before cutting, the 30-centimeter-diameter pipe was covered with urethane to prevent radioactive materials from leaking out of the pipe when it was cut. However, the cut surface with the high radiation dose did not have a lid, and the inside of the other cut surface, which had a lid, was 120 millisieverts per hour.
 The pipes were used for venting highly contaminated steam from the reactor to prevent the containment vessel from rupturing at the beginning of the accident in March 2011. Akira Ono, chief executive officer of the Fukushima Daiichi Decommissioning Promotion Company, said at a press conference on March 26, “The high concentration is thought to be caused by the venting. We need to work carefully and consider our procedures.
 The removal of piping using remote-controlled equipment began at the end of February, but was suspended for about two months due to a series of troubles that forced a review. The plan was to cut and remove a total of 135 meters of piping in 26 installments, and the first installment was finally completed on the 23rd of this month. (The first round finally succeeded on the 23rd of this month.)
https://www.tokyo-np.co.jp/article/180011?fbclid=IwAR2XsD9rjbecMFSYfUWU8knhoQKVjtibdDHl4InGGWLwRm5DKbpypkwhRaw

May 29, 2022 Posted by | Fuk 2022 | , , | Leave a comment

TEPCO to Remove Contaminated Pipes at Fukushima Daiichi Nuclear Power Plant by “First Half of FY2022” Due to Continuing Troubles

A cutting device lifted by a large crane grabs a 30-centimeter-diameter pipe at the Fukushima Daiichi Nuclear Power Plant on March 2, 2022 (photo by Takeshi Yamakawa)

April 18, 2022
On April 18, at a meeting of the Nuclear Regulation Authority to review the status of the accident at the Fukushima Daiichi Nuclear Power Plant, TEPCO announced that it had changed its target date for the completion of work to “the first half of FY2022 (April to September)” regarding the removal of pipes between Units 1 and 2 that were contaminated with high concentrations of radioactive materials. Previously, the target was “within FY 2009. The scope of the removal work includes the areas that interfere with the installation of rainwater inflow countermeasures in the waste treatment buildings of Units 1 and 2 and the installation of a large cover in Unit 1.
 The removal work began on February 24, but has not progressed at all due to a series of problems with the cutting equipment. The timing for the resumption of work is not clear, as investigations are still underway to determine whether the cutting equipment and method used to lift the pipes up by a large crane are appropriate.
 The pipes to be removed were used in the venting process immediately after the accident to release contaminated air inside the reactor to prevent the containment vessel from rupturing. The pipes are 30 cm in diameter and measure 65 meters on the Unit 1 side and 70 meters on the Unit 2 side. The current plan is to cut the piping into 26 sections and remove them. The surface dose at the connection with the exhaust stack is 4 sievert per hour, which is high enough to kill a person if he or she stays there for several hours. For this reason, all work will be carried out remotely. (Shinichi Ogawa)
https://www.tokyo-np.co.jp/article/172472?rct=national&fbclid=IwAR1DYTcIpK–IpNqQfheOVBWKG8-G1Eonb274DLuS8FOMWxZ9ciYQLdmaiM

April 23, 2022 Posted by | Fuk 2022 | , , , | Leave a comment

Chain cutting device breaks off this time, and no progress in removing contaminated piping at TEPCO’s Fukushima Daiichi Nuclear Power Plant

Cutting equipment (center) lowered by crane to remove pipes contaminated by venting (exhaust) at the beginning of the accident. At this point, the cutting equipment malfunctioned at the TEPCO’s Fukushima Daiichi Nuclear Power Plant at 3:02 p.m. on March 2, 2022 (photo by Takeshi Yamakawa).

March 3, 2022
TEPCO announced on February 3 that its cutting equipment failed for the second day in a row in cutting pipes contaminated with highly radioactive materials between Units 1 and 2 at the Fukushima Daiichi Nuclear Power Plant (Okuma and Futaba, Fukushima Pref.) One week after work began on February 24, the cutting of 26 separate sections has not progressed at all, and the procedure will be reviewed.

 The radiation level at the site is extremely high due to the contaminated pipes being near the ground, and people continue to be unable to approach the site. TEPCO planned to remove the pipes because they would be an obstacle to the planned work to cover the Unit 1 reactor building with a cover.
 The work was carried out by remotely operating a cutting device attached to a large crane, and on the 1st, one of the two chain-like cutting devices came off, and on the 2nd, the same device broke.
 According to TEPCO, before the failure on the 1st, an alarm was triggered indicating an increase in the concentration of radioactive materials contained in the chips from the cut section of the pipe, and on the 2nd, the alarm sounded again, so the speed of the cutting device was reduced to prevent the production of many chips, but the device broke after cutting about one third of the pipe. The cause is believed to be premature wear of the device.
 The pipes, each about 30 centimeters in diameter and measuring about 65 meters on the Unit 1 side and about 70 meters on the Unit 2 side, were cut into 26 sections and removed. (The plant was used to vent contaminated steam from inside the reactor to prevent the containment vessel from rupturing in March 2011.)
https://www.tokyo-np.co.jp/article/163463?fbclid=IwAR0W4Rv8sxOLCLhbCzOqq6x8OgRxXGMIjDyAYH0BpNXIf9x2p4HZf4Xaac8

March 7, 2022 Posted by | Fuk 2022 | , | Leave a comment

There was no wind… but the cutting equipment came off and stopped. Removal of contaminated pipes at TEPCO’s Fukushima Daiichi Nuclear Power Plant

March 1, 2022
On January 1, TEPCO began cutting pipes contaminated with highly radioactive materials between Units 1 and 2 at the Fukushima Daiichi Nuclear Power Plant (Okuma and Futaba, Fukushima Prefecture), but stopped shortly after starting due to a problem with the cutting equipment.

The cutting equipment (center) was hung by a crane. The pipe could not be cut due to a malfunction at TEPCO’s Fukushima Daiichi Nuclear Power Plant at 2:50 p.m. on March 1 (from TEPCO’s live camera).

 The site was inaccessible due to high radiation levels, and the work was performed by remote control of a cutting device that was suspended from a large crane. According to TEPCO, around noon on January 1, they began cutting pipes near ground level on the Unit 2 side, but were unable to continue after 15 minutes. A part of a chain-like cutting device called a wire saw came off.
 The work to remove the pipes began on February 24, but the cutting equipment, which had been hung by a crane, was blown away by strong winds, preventing the work from getting underway.
 The pipes are about 30 cm in diameter and measure about 65 meters on the Unit 1 side and about 70 meters on the Unit 2 side. The plan is to cut the pipes into 26 sections, which were used for venting contaminated steam inside the reactor to prevent the containment vessel from rupturing at the time of the accident in March 2011. Remove it.
 Removal of the crane was originally scheduled to begin in October of last year and be completed in March of this year, but has been delayed significantly due to a series of crane failures. (Kenta Onozawa)

https://www.tokyo-np.co.jp/article/163034?fbclid=IwAR0Y1Nyx7RxYJHRHnUH6tNFUpV7NnC8nD91pzfYchvQvKcizBc7ykS-G6XI

March 3, 2022 Posted by | Fuk 2022 | , , | Leave a comment

TEPCO begins removal of pipes contaminated at the time of the Fukushima Daiichi Nuclear Power Plant accident.

March 1, 2022
On January 1, TEPCO began removing pipes in Units 1 and 2 of the Fukushima Daiichi Nuclear Power Plant that were contaminated with radioactive materials when they were vented to prevent damage to the plant. After the pipes are disconnected, TEPCO plans to investigate the situation with the Nuclear Regulation Commission.

The pipes to be removed are called “SGTS pipes” and are used to filter out gases in the reactor building during an accident.

TEPCO has begun removing the piping from the portion of the piping that goes outdoors because it will interfere with the installation of a large cover to cover the entire Unit 1 reactor building, which experienced a hydrogen explosion.

The pipes to be removed are approximately 65 meters long on the Unit 1 side and 70 meters long on the Unit 2 side. At the time of the accident 11 years ago, the containment vessel covering the reactor was contaminated when it was vented to release gases containing radioactive materials to prevent it from being damaged by the internal pressure.

Radiation levels of up to 160 millisieverts per hour were observed in the pipes when they were surveyed last May.

TEPCO and the Nuclear Regulation Authority (NRA) plan to examine the severed pipes to determine the effects of the “vent” on the pipes’ contamination and other factors.

The removal work is scheduled to last until the end of this month, but according to TEPCO, the work was suspended for one day due to a malfunction of the shredding equipment, and the cause is being investigated.
https://www3.nhk.or.jp/news/html/20220301/k10013507101000.html?fbclid=IwAR0yB_LUsoi0sKIPR0-jh-R6u7KmMGo93QQ7OjxMCbIp-WKesxtLvm_nIh8

March 3, 2022 Posted by | Fuk 2022 | , , | Leave a comment