All systems ready for Fukushima fuel removal
Engineers at Fukushima Daiichi have done final checks before they begin removing fuel from unit 4’s storage pond, the highest priority safety-related task in the site’s decommissioning.
Technicians within the new building cover. The empty reactor vessel is beneath the circular section, the rectangular part is the used fuel pool (Image: Tepco)
A fuel transport container will be placed in the pool using the main crane. Workers will then use the smaller refuelling crane to move fuel assemblies one by one from their vertical storage racks to the container. When this is full it will be sealed, lifted from the water by the main crane, placed on the service floor for decontamination and then taken through a special route to a vehicle that will move it across the site to be unloaded at the site’s shared storage facility. This process will be repeated until the pool is empty.
With a total of 1533 fuel assemblies in the pool (1331 used, 202 unused) this is expected to take until the end of 2014. Tepco will move the fuel during the day and clean dust and debris from the pool water during the night. Two containers will be used in relay.
The Nuclear Regulatory Authority granted its approval for the security and radiological protection aspects of the work yesterday, and Tepco engineers conducted final functional checks of the cranes using non-radioactive dummy fuel today. One more round of feedback from local people is required before the operations begin, perhaps as soon as next week.
Unit 4 was off line for maintenance at the time of the 2011 accident with its full core load of fuel, as well as used fuel from previous operation, stored in a fuel pool at the top of the reactor building. Although this meant there was no possibility of a reactor accident at unit 4, there was a risk of the pool overheating. The stability of the pool was then reduced by major structural damage to the building caused by the ignition of hydrogen that leaked through ventilation systems shared with unit 3.
The building has since been reinforced, and thousands of tonnes of debris and rubble have been removed from its roof. The new cover has been constructed with all the fuel handling equipment of a normal nuclear power plant and inspections of the pool have shown the fuel to be undamaged and not suffering from corrosion.
Source: World Nuclear News
Preliminary Test Now Required For Fukushima Nuclear Cleanup
Not so fast with the Fukushima decommissioning, TEPCO. A Japanese government-affiliated agency (the Japan Nuclear Energy Safety Organization) has advised the Tokyo Electric Power Company that its proposed method of clearing Reactor Unit 4′s exposed cooling pool needs a test run before anyone commits to a full-scale plan. Japan Times reports that conducting and evaluating the test may add another two weeks to the cleanup schedule.
TEPCO had devised a plan to start removing fuel rods from the stricken reactor containment as early as Friday. Mirroring international fears about the situation and concerns that U.S. Energy Secretary Ernest Moniz expressed during his visit last Friday, the energy bureau has limited the utility’s program to one initial safety test, sources close to the matter told the Japan Times on Monday. Sea water corrosion, three explosions, fallen debris, likelihood of fuel rod breakage and uranium pellets escaping, and the possibility of rods colliding all increase the danger of further nuclear compromise at the unit.
Fukushima nuclear operator Tepco ‘should split up’
The operator of Japan’s stricken Fukushima nuclear power plant should be broken up, a committee is set to propose according to unnamed sources.
The ruling party panel wants part of the Tokyo Electric Power Company in charge of cleaning to be separated.
Fukushima has been beset by problems – including toxic water leaks – since it was damaged by the earthquake and tsunami of March 2011.
The clean up is expected to take 40 years and cost at least $100bn (£62bn).
Nearly 100,000 people are still unable to return to their homes because of high levels of radiation.
Previous Fukushima problems
- 9 Oct Six workers at Japan’s Fukushima nuclear plant have been doused in radioactive water, Tepco says
- 7 Oct A plant worker accidentally switches off power to pumps used for cooling damaged reactors
- 3 Oct Tepco says there is a radioactive water leak after workers overfill a storage tank
- 21 Aug Japan’s nuclear agency upgrades Fukushima alert level
- 20 Aug Tepco says 300 tonnes of radioactive water has leaked from a storage tank into the ground
- July Tepco for the first time admits radioactive water is going into the sea
- June Tepco says radioactive water leaking from a storage tank to the ground
- April Tepco suspects a fresh radioactive water leak at Fukushima
- March Tepco suspects a rodent may have been behind a power cut that shut down cooling systems
- Dec 2011 Contaminated water leaks from a treatment system, caused by a crack in the foundation
Cooling systems for reactors at Fukushima were knocked out during the disaster, causing meltdowns at three of them.
Water is being pumped in to cool the reactors. However, this creates large amounts of contaminated water that must be stored securely.
Some of the water has leaked from the tanks, pipes and damaged structures, leading to concerns contaminated water is mixing with groundwater that is flowing into the sea.
Workers have been batting to contain the toxic water leaks and there are reports that they are suffering from low morale and exhaustion.
The panel from the Liberal Democratic Party (LDP) is tasked with the recovery of areas devastated by the earthquake and tsunami.
The panel says Japan’s Fukushima disaster needs to be dealt with by a small, specialist company focused entirely on the clean-up operation, local media report.
It is expected to hand their proposals to Prime Minister Shinzo Abe next week, Reuters news agency says, citing a source familiar with the matter.
It will recommend “creating a clear and realistic organisation” for operations at Fukushima, the source added.
The proposals come after months of intense criticism of Tepco, which owns the plant and is currently responsible for the clean-up.
The idea is that the part of Tepco responsible for the clean-up would be split off, while the rest of the corporation would be allowed to return to its core business of generating electricity, says the BBC’s Rupert Wingfield-Hayes in Tokyo.
Source: BBC News
Chernobyl fuel transfer milestone
The transfer of undamaged used fuel to an on-site interim storage facility from units 1 to 3 of the Chernobyl nuclear power plant in Ukraine has now been completed.
Source: World Nuclear News