Reactor2 « nuclear-news

Unit 2 of Genkai NPP will be decommissioned.

Unit 3 and 4 of Genkai are still operating.

Kyushu Electric Power Co. said Wednesday it will scrap No. 2 reactor at its Genkai nuclear power plant in Saga Prefecture, seen in the forefront left of this photo taken in January

Feb 13, 2019

FUKUOKA – Kyushu Electric Power Co. said Wednesday it has decided to scrap its aging No. 2 reactor at its Genkai nuclear plant in Saga Prefecture.

The utility abandoned a plan to restart the unit, which has an output of 559 megawatts, in the face of the huge costs involved in enhancing the safety of the reactor that is already near the end of its 40-year operating life.

The reactor, which started operating in March 1981, has been idled since a routine checkup shortly before the March 2011 earthquake and tsunami disaster that triggered the Fukushima nuclear crisis.

The Genkai plant consists of four units. The utility already decided in 2015 to scrap its aging No. 1 unit, which had the same output capacity as the No. 2 reactor. Decommissioning work at the No. 1 reactor started in July 2017 and is expected to continue through fiscal 2043.

There have been a number of operational problems at the Genkai power plant. In May last year, pumps installed to control the circulation of cooling water at the No. 4 unit suffered malfunctions, following a steam leak from a pipe at the No. 3 reactor just a week after it was reactivated in March.

Some local residents have sought to stop operation of the Nos. 3 and 4 units with a temporary injunction, with doubts about the safety measures taken and citing the risk of volcanic eruptions in the region. Their case is pending at the Fukuoka High Court.

https://www.japantimes.co.jp/news/2019/02/13/national/kyushu-electric-scrap-no-2-reactor-genkai-nuclear-plant-due-cost-upgrading-safety-aging-site/?fbclid=IwAR38eujKnFK_AcrWMime4iH5hFfc-YQt8PmRvlaggVG6MAz2DoSa_hMCMD4

February 18, 2019 Posted by dunrenard | Japan | decommissioning, Genkai NPP, Reactor2 | Leave a comment

One more expensive robot to go probe in and to get fried

Toshiba Corp.’s energy systems unit group manager Jun Suzuki shows a remote-controlled melted fuel probe device at its facility in Yokohama, near Tokyo, Monday, Jan. 28, 2019. Toshiba unveiled the device carrying tongs that comes out of a long telescopic pipe for an internal probe in one of three damaged reactor chambers at Japan’s

A remote-controlled melted fuel probe device is unveiled by Toshiba Corp. at its facility in Yokohama, near Tokyo, Monday, Jan. 28, 2019. Toshiba unveiled the device carrying tongs that comes out of a long telescopic pipe for an internal probe in one of three damaged reactor chambers at Japan’s tsunami-hit Fukushima nuclear plant – this time to touch chunks of melted fuel.

Toshiba unveils robot to probe melted Fukushima nuclear fuel

Jan. 28, 2019

YOKOHAMA, Japan (AP) — Toshiba Corp. has unveiled a remote-controlled robot with tongs that it hopes will be able to probe the inside of one of the three damaged reactors at Japan’s tsunami-hit Fukushima nuclear plant and manipulate chunks of melted fuel.

The device displayed Monday is designed to slide down an extendable 11-meter (36-foot) long pipe and grip highly radioactive melted fuel inside the Unit 2 reactor’s primary containment vessel.

An earlier robot captured images of pieces of melted fuel in the reactor last year, but other details of the fuel’s status remain largely unknown.

Toshiba’s energy systems unit said experiments with the new probe planned in February are key to determining the technologies needed to remove the fuel debris, the most challenging part of the decades-long decommissioning process.

https://abcnews.go.com/Technology/wireStory/toshiba-unveils-robot-probe-melted-fukushima-nuclear-fuel-60673515

Robot to examine fuel debris in Fukushima unit

29 January 2019

Toshiba has developed a remotely-operated robot to investigate debris in the bottom of the primary containment vessel (PCV) of unit 2 at the damaged Fukushima Daiichi nuclear power plant in Japan.

The device developed by Toshiba for examining debris in unit 2’s PCV (Image: Toshiba)

A pre-investigation of the area directly below the pressure vessel – known as the pedestal – was carried out in January 2017 at Fukushima Daiichi 2 using a remotely operated camera on a telescopic probe. Photos taken during that investigation showed a black mass and deposits near a grating in the pedestal area, possibly melted nuclear fuel.

The following month, Tokyo Electric Power Company (Tepco) sent a “scorpion-shaped” robot – developed jointly by Toshiba and the International Research Institute for Nuclear Decommissioning (IRID) – into the PCV of unit 2. Although the robot was unable to reach the part of the vessel directly under the reactor pressure vessel, the company said the information it gathered would help it determine how to decommission the unit.

In January 2018, an internal investigation of the PCV of unit 2 using a suspended pan-tilt camera attached to a telescopic guiding pipe identified deposits and fuel assembly components at the bottom of the pedestal area.

Yesterday, a robotic device developed by Toshiba Energy Systems & Solutions Corporation was unveiled that will be used to explore these deposits. The device – approximately 30cm in length and 10cm in width – features a camera, LED lighting, a pan-tilt mechanism, finger drive mechanism (tongs), radiation dosimeter and a thermometer.

“Using know-how cultivated through previous investigations at the Fukushima Daiichi nuclear power plant, Toshiba ESS added a finger drive mechanism for touching the deposits to investigate their condition to the telescopic guiding pipe developed last January,” the company said.

“Until now we have only seen those deposits, and we need to know whether they will break off and can be picked up and taken out,” Jun Suzuki, a Toshiba ESS group manager for the project, told Japan Today. “Touching the deposits is important so we can make plans to sample the deposits, which is a next key step.”

The robotic device is scheduled to be deployed to investigate the interior of unit 2’s PCV next month.

Tepco has also carried out robotic surveys of the PCVs of units 1 and 3 at the Fukushima Daiichi plant.

In March 2017, Tepco carried out an investigation of the PCV of unit 1 using the PMORPH robot developed by Hitachi-GE Nuclear Energy and IRID. Equipped with a dosimeter and waterproof camera, it took radiation readings and digital images at ten different measurement points within that unit’s PCV.

In July that year, it inserted a screw-driven submersible robot developed by Toshiba and IRID into unit 3’s PCV.

Goro Yanase, vice president of Toshiba ESS’s Nuclear Energy Systems & Services Division, said: “We will continue to advance technology development and contribute to investigation of the interior of the Fukushima reactors.”

http://www.world-nuclear-news.org/Articles/Robot-to-examine-fuel-debris-in-Fukushima-unit

February 3, 2019 Posted by dunrenard | fukushima 2019 | Fukushima Daiichi, Reactor2, Robot Probe | Leave a comment

Tepco to temporarily stop injecting water at Fukushima reactor

November 9, 2018

Tepco to temporarily stop injecting water at Fukushima reactor
The operator of the Fukushima Daiichi nuclear power plant plans to temporarily stop injecting water into one of its damaged reactors to test the cooling of fuel debris.
Tokyo Electric Power Company announced it will conduct the 7-hour test at the No.2 reactor as early as March next year.
The unit is one of 3 in the 6-reactor facility that suffered a meltdown after the March 2011 earthquake and tsunami. The damaged reactors contain a mixture of molten nuclear fuel and structural parts.
TEPCO officials say water injections keep temperatures stable in the 3 reactors at around 30 degrees Celsius.
The planned experiment is aimed at checking how the debris is being cooled. It will be the first time to halt water injections into the reactor since they were stabilized after the accident.
TEPCO’s assessment says the reactor temperature would rise by around 5 degrees per hour if injections were halted by accident. But it says the rise will be limited to about 0.2 degrees per hour when natural heat radiation is taken into account.
TEPCO officials say they will begin cutting back on water injections by around half to 1.5 tons per hour for about a week as early as in January, before halting them completely in March after checking the results.
TEPCO estimates the 7-hour stoppage may raise the reactor temperature by about 1.4 degrees but says water injections will resume if the temperature rises more than 15 degrees.
Company officials say they want to assess changes in the temperature so they can use the data in future emergency cases, including earthquakes and tsunamis.
https://www3.nhk.or.jp/nhkworld/en/news/20181109_10/

November 17, 2018 Posted by dunrenard | Fukushima 2018 | Fuel Debris, Fukushima Daiichi, Reactor2 | Leave a comment

Radiation still too high in reactor# 2 building

July 2, 2018

A robotic probe has found that radiation levels remain too high for humans to work inside one of the reactor buildings at the damaged Fukushima Daiichi nuclear power plant.

Tokyo Electric Power Company, the operator of the plant, plans to relocate 615 units of nuclear fuel from the spent fuel pool, which is located on the top floor of the No. 2 reactor building and is separate from the reactor itself.

TEPCO says the relocation will help reduce risks, including possible damage caused by earthquakes.

The No. 2 reactor underwent a meltdown, but did not experience a hydrogen explosion in the 2011 nuclear accident. The building is likely to still have a high concentration of radioactive materials.

Last month, TEPCO drilled a hole in the wall of the building in order to use a camera-equipped robot to create a detailed map of the radiation on the top floor.

On Monday, workers started the survey and measured radiation levels at 19 points, mainly near the opening. Up to 59 millisieverts were detected per hour.

That’s above workers’ allowable annual exposure of 50 millisieverts and more than half of their 5-year exposure limit. TEPCO has concluded it cannot let humans work inside the building.

TEPCO will use the results to determine specific ways to remove the fuel from the pool. It plans to start the work in fiscal 2023.

https://www3.nhk.or.jp/nhkworld/en/news/20180702_35/