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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

April 17, 2011- Day 38 of Disaster
Reactor shutdowns nine months away
Ban lifted on more Fukushima milk shipments
Robots Enter Fukushima Reactor Building for First Time
Tepco Sets Out Plan to End Fukushima Nuclear Crisis by October

April 16, 2011 - Day 37 of Disaster
Nuclear plants ordered to check outside power links
Tepco to meet 95% of demand
Despite Fukushima, Manmohan bats for nuclear energy
Nuclear Energy's Grim Future
Gov't OKs raw milk shipments from another 25 Fukushima municipalities
Seawater radioactivity rises inside containment fence
Japan says 28 plant workers got high radiation doses
Nuclear-themed movies to be shown in Tokyo for Chernobyl anniversary

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.

April 15, 2011 - Day 36 of Disaster
JAIF Update (PDF)
Fuel rod fragments at bottom of vessels
U.S. lifts advisory for families of embassy staff to leave Japan
Toshiba to revise nuclear power business plan

NEI Update

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.

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.

April 14, 2011 - Day 35 of Disaster
Tests Confirm Damage to Unit 4 Spent Fuel at Fukushima Daiichi
Information on Status of Nuclear Power Plants in Fukushima
Japan Quake Map

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.
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

April 13, 2011 - Day 34 of Disaster
Information on Status of Nuclear Power Plants in Fukushima
Radiation surges above 4's fuel pool
East Fukushima shiitake banned
TEPCO president mulls paying damages; says he won't resign
Work continues to remove toxic water, cool spent nuke fuel pools
Comparing Japan and Chernobyl

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


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


The suppression pool is the torus shaped device at the bottom of the reactor. You can see an image here:

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


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

April 2 - 9, 2011 Updates

March 27 - April 1, 2011 Updates

March 11 - 26, 2011 Updates