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March 21, 2011
The nuclear
power plants in Japan after the March 11 , 2011 earthquakes could become
a major nuclear disaster.
Keep watching this page for updates and insights by Raymond Rouse on the
issues from a nuke scientist's point of view.
Continuing
Updates:
IAEA
Status of Fukushima
INES
Leaflet on Nuclear Accidents
Continuing
Updates on Earthquakes around the world
1. Current Situation
Overall, the situation at the Fukushima Daiichi
nuclear power plant remains very serious but there are early signs of
recovery in some functions, such as electrical power and instrumentation.
Changes to Fukushima Daiichi Plant Status
The transfer of contaminated water from the
trench of the Unit 2 Turbine Building to the condenser started on 12 April
and continued on 13 April until approximately 660 tonnes were transferred.
To minimize the movement of contaminated
water to the open sea, temporary boards to stop water (3 steel plates
in total) were installed on 13 April on the ocean-side of the Inlet Bar
Screen of Unit 2.
Silt fences have also been installed in the
inlet canal and in front of the Inlet Bar Screens of Units 1, 2, 3 and
4. On 11 April, a silt screen was installed at the southern end of the
inlet canal. The installation in front of the Inlet Bar Screen of Units
3 and 4 was completed on 13 April and for Units 1 and 2 on 14 April.
As of 14 April, white "smoke" was
still observed coming from Units 2 and 3. White "smoke" was
also observed coming from Unit 4 on 14 April.
On 13 April, Japan's Nuclear and Industrial
Safety Agency (NISA) reported that the Tokyo Electric Power Compan (TEPCO)
had begun to install a backup line for providing fresh water to the Reactor
Pressure Vessels (RPVs) at Units 1, 2, and 3.
In Unit 1, fresh water is being continuously
injected into the RPV through the feed-water line at an indicated flow
rate of 6 m3/h using a temporary electric pump with off-site power. In
Units 2 and 3, fresh water is being continuously injected through the
fire extinguisher lines at an indicated rate of 7 m3/h using temporary
electric pumps with off-site power.
Nitrogen gas is being injected into the Unit
1 containment vessel to reduce the possibility of hydrogen combustion
within the containment vessel. The pressure in this containment vessel
has stabilised. The pressure in the RPV is increasing as indicated on
one channel of instrumentation. The other channel shows RPV pressure as
stable. In Units 2 and 3 Reactor Pressure Vessel and Drywell pressures
remain at atmospheric pressure.
RPV temperatures remain above cold shutdown
conditions in all Units, (typically less than 95 °C). In Unit 1, the
temperature at the feed water nozzle of the RPV is 197 °C and at the
bottom of the RPV is 119 °C. In Unit 2, the temperature at the feed
water nozzle of the RPV is 150 °C. In Unit 3 the temperature at the
feed water nozzle of the RPV is 91 °C and at the bottom of the RPV
is 121 °C.
On 14 April, a concrete pump truck, with
a capacity of 50t/h, began spraying fresh water to the Unit 3 spent fuel
pool. In Unit 4, a sample of the water in the spent fuel pool was collected
for analysis.
There has been no change in status in Unit
5 and 6 and the Common Spent Fuel Storage Facility.
NEI Update
UPDATE AS OF 6:30 P.M. EDT, THURSDAY, APRIL
14:
NEI has uploaded a new video to its YouTube channel. The video, "INL
Director Explains How the National Labs Are Assisting With Japan's Nuclear
Crisis," features the Idaho National Laboratory's Director John Grossenbacher,
who discusses the types of nuclear expertise and capabilities that exist
within the U.S. Department of Energy's national labs to assist with the
Japan nuclear crisis. He also explains how the labs will provide long-term
research that will uncover lessons learned from the Fukushima nuclear
plants.
UPDATE AS OF 11 A.M. EDT, THURSDAY, APRIL 14:
Tokyo Electric Power Co. (TEPCO) has moved highly contaminated water from
a concrete enclosure outside reactor 2 at the Fukushima Daiichi nuclear
power plant, the utility reported. TEPCO said the water is stored in the
reactor’s condenser.
To help keep radioactive water from diffusing
into the ocean near the plant, TEPCO has installed an underwater silt
fence in front of the intake screen for reactors 3 and 4.
Radioactive water that has accumulated in
turbine room basements is interfering with work to restore cooling operations
at the site. TEPCO is completing preparations to transfer the contaminated
water to the plant's radioactive water processing facility and other temporary
storage locations.
TEPCO continues to inject cooling water into
reactors 1, 2 and 3 and to spray water as needed into the used fuel pools
for reactors 1-4. TEPCO also continues injection of nitrogen gas into
the containment vessel of reactor 1 to prevent the potential for an explosion
of hydrogen that may be accumulating inside.
Workers continued Thursday to move emergency
diesel generators to higher ground to keep them safe from aftershocks
and tsunamis, the Japan Atomic Industrial Forum reported. An aftershock
on Monday briefly disrupted electric power at the Daiichi plant, and a
series of aftershocks has rattled the plant several times this week, causing
no further damage. TEPCO also is rewiring the external power lines to
avoid a total blackout.
TEPCO confirms damage to part of No. 4 unit's
spent nuke fuel
TOKYO, April 14, Kyodo
Some of the spent nuclear fuel rods stored in the No. 4 reactor building
of the crisis-hit Fukushima Daiichi power plant were confirmed to be damaged,
but most of them are believed to be in sound condition, plant operator
Tokyo Electric Power Co. said Wednesday. The firm known as TEPCO said
its analysis of a 400-milliliter water sample taken Tuesday from the No.
4 unit's spent nuclear fuel pool revealed the damage to some fuel rods
in such a pool for the first time, as it detected higher-than-usual levels
of radioactive iodine-131, cesium-134 and cesium-137. The No. 4 reactor,
halted for a regular inspection before last month's earthquake and tsunami
disaster, had all of its 1,331 spent fuel rods and 204 unused fuel rods
stored in the pool for the maintenance work and the fuel was feared to
have sustained damage from overheating. The cooling period for 548 of
the 1,331 rods was shorter than that for others and the volume of decay
heat emitted from the fuel in the No. 4 unit pool is larger compared with
pools at other reactor buildings.
According to TEPCO, radioactive iodine-131 amounting to
220 becquerels per cubic centimeter, cesium-134 of 88 becquerels and cesium-137
of 93 becquerels were detected in the pool water. Those substances are
generated by nuclear fission. The government's Nuclear and Industrial
Safety Agency said the confirmed radioactive materials were up to 100,000
times higher than normal but that the higher readings may have also been
caused by the pouring of rainwater containing much radioactivity or particles
of radiation-emitting rubble in the pool. The roof and the upper walls
of the No. 4 reactor building have been blown away by a hydrogen explosion
and damaged by fires since the disaster struck the plant. The water level
in the spent fuel pool is believed to have temporarily dropped.
TEPCO said the fuel rods may have also been damaged by
steel frames that fell into the pool in addition to overheating caused
by the loss of cooling functions after the twin disasters.
The utility plans to examine the condition of the plant's reactor buildings
by deploying a small unmanned helicopter to see whether it is possible
to extract spent fuel from pools.
The nuclear agency said now that the condition of the No. 4 unit pool
is partially known, workers can better prepare for recovery works there.
Earlier in the day, the government's nuclear regulatory agency ordered
TEPCO to check the quake resistance of reactor buildings at the Fukushima
plant, which have been rocked by strong aftershocks from the magnitude-9.0
earthquake that wrecked the site and triggered tsunami on March 11. The
agency told the utility to immediately examine the buildings and consider
reinforcement work if they are judged as not sufficiently quakeproof.
In addition to the No. 4 unit, the Nos. 1 and 3 reactor buildings have
also been severely damaged by hydrogen explosions in the early days of
the crisis. ''As strong aftershocks occur almost daily, we have to consider
what will happen to buildings already damaged by blasts,'' said Hidehiko
Nishiyama, a spokesman for the nuclear agency. He acknowledged the difficulties
involved in the work to reinforce the quake resistance of the buildings,
where radiation levels are high, but said, ''We must devise some ways.''
The agency urged TEPCO to report back to it on the matter as soon as possible.
Meanwhile, Yoko Komiyama, senior vice minister of health,
labor and welfare, said Wednesday at a Diet session that a total of 22
workers at the plant have been exposed to radiation exceeding 100 millisieverts
as of early Wednesday and that the highest level of exposure among them
is 198.24 millisieverts. Exposure to 100 millisieverts is the permissible
level for nuclear plant workers dealing with an emergency, but the limit
has been raised to 250 millisieverts for the ongoing crisis.
Workers continued Wednesday to remove highly radioactive
water in the plant as part of efforts to put an end to the emergency,
which is now acknowledged as one of the world's worst nuclear disasters.
TEPCO had pumped out 700 tons of highly polluted water by Wednesday evening
from an underground tunnel-like trench to a ''condenser,'' where in normal
operations steam from the reactor is converted into water. Eventually,
the operator plans to remove a total of 60,000 tons of contaminated water,
found in the basements of the Nos. 1 to 3 reactor turbine buildings as
well as the trenches connected to them, and to store it in nearby tanks
and other areas.As a result of the operation, the level of highly radioactive
water that had been filling up the trench connected to the No. 2 reactor's
turbine building was lowered. Nishiyama said it will likely take several
weeks before the tainted water removal operation ends. The highly toxic
water is believed to originate from the No. 2 reactor's core, where fuel
rods have partially melted. The water, which has also affected other parts
of the plant, is hampering efforts to restore the reactors' key cooling
functions, lost in the March 11 earthquake and tsunami. The nuclear agency
also said TEPCO has installed three steel sheets near a seawater intake
for the No. 2 reactor and set up ''silt fence'' curtain barriers near
intakes for the Nos. 3-4 reactors at the six-reactor plant to block the
spread of radioactive substances in water. Massive amounts of water have
been poured into the reactors and their spent nuclear fuel pools as a
stopgap measure to cool them down at the Fukushima plant. But pools of
contaminated water have been detected in various parts of the nuclear
complex on the Pacific coast, with some water leaking into the sea, as
an apparent side effect of the emergency measure. TEPCO successfully stopped
the leak of highly radioactive water from a cracked pit on April 6.
==Kyodo
Copyright 2011 Kyodo News. All Rights Reserved.
TEPCO confirms damage to part of No. 4 unit's spent nuke fuel Kyodo 2011-04-14T00:28:09+0900
Kyodo
The latest from the N.E.I. on Fukushima:
Authorities said much of the high-level radiation leaked
from reactor 2 on March 15 and 16, early in the accident. Abnormalities
in the reactor's suppression pool caused the radiation release, the Japan
Nuclear Safety Commission said.Radiation continues to leak from the suppression
pool, the commission said, but the volume has dropped considerably.
Is the "suppression pool" the same as the spent
fuel storage pool? I wouldn't think so. But I've not heard the term before
in reference to BWRs.
Ed Hiserodt
Controls & Power, inc.
Little Rock
Answer:
No a suppression pool is also known as a Torus, it is
a giant heat sink designed to supply water to the reactor in the event
of a Loss of Coolant Accident (LOCA). If the reactor suffers a severe
pipe shear water would drain into the Torus that water can be cooled and
returned
back to the reactor using various systems. It is also design to relieve
pressure from the Drywell. If the Drywell is vented to the Torus the over
pressure can be relived using cooling system designed the spray the contents
with cold water ie. Torus spray. - Raymond Rouse
Answer:
The suppression pool is the torus shaped device at the
bottom of the reactor. You can see an image here: http://www.nucleartourist.com/type/bwr.htm
In case of a pressure (steam) build up in the drywell,
the pressure can be vented into the wetwell (suppression pool). The wetwell
has a large volume of water which acts to cool the steam. The steam released
from the reactor pressure vessel can contain various radionuclides depending
upon the amount of damage suffered by the fuel rods.
This was the source of the radioactivity in the suppression
pool. - Jeff Terry Asst. Professor of Physics
Answer:
Exactly the Wet well being 1/2 filled with water vs Drywell
which is Dry (inerted with a non combustible gas)- Raymond Rouse
April 12, 2011 - Day 33
of Disaster
Fukushima
Crisis Now at Chernobyl Level
Japan
nuclear agency raises threat level
Nuclear
disaster's impact
April 11, 2011 - Day 32 of Disaster
Japan
Evacuation: Government Expected to Extend Evacuations Over 18 Miles
Magnitude
7.1-Quake Jolts Japan Coast
Japan
Aftershock: 7.1 Earthquake, Another Tsunami Warning Comes On One Month
Anniversary
April 10, 2011 - Day 31 of Disaster
Japan
Nuclear Plant Fails to Stop Radioactive Water From Spilling into Ocean
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