To English top page

Explanation 4

Even if nuclear power plants carry out a scram, the accident happens.

It is said the operation system of the nuclear power plants of Hamaoka will stop by the shake of seismic intensity 6 automatically. But while the land continues shaking who can insert the control rod well? (Fig. 29)

Fig. 29

Even if it is possible to stop it well, you have to continue turning cooling water. Cooling water leaked in the Tsuruga nuclear power plant on July 12, 1999. From the small crack of branched piping / 0.2mm width of 8cm length width 51t water (=1/5 of the whole cooling water) was lost.

Fortunately since the speed of the lost was 10t water in 1 hour at the maximum, it was able to continue being supplied the same amount water.

If the piping breaks by a big earthquake and the cooling (irrigation) equipment for emergencies is not enough to supply the lost water, what will happen?

The piping explosion accident happened at the No. 1 furnace in November 2001. It was a piping that leads to the cooling device for emergencies.

One of two lines of the high-pressure pouring system that pushes the cooling water into a furnace resisting the pressure of the steam in it lost its function.

The heavy and steel-made pressure vessel of nuclear reactor, the thick and long piping, the low-pressure tank of the reactor core cooling (irrigation) equipment for emergencies, each of them will shake in different way. Very large pressure should be applied to a joint of these equipments. Especially No. 1 and 2 furnaces constructed 20 years ago or more.

In some old nuclear power plants, the accidents caused by the distortion and the corrosion of welding overlap have taken place several times. We should consider that the cooling-water loss accident could happen by an earthquake. We must also consider it could be the large-scale cooling-water loss which results in a nuclear core meltdown and container destruction.

If the big accident occurs in the nuclear power plants of Hamaoka

Immediately after the operation stop a nuclear reactor has the radioactivity that hits 1 billion to 1 trillion persons' fatal dose if it enters inside the body.

Ken Senoo (deceased), who was a assistant of the Kyoto University nuclear reactor experiment place, performed calamity anticipation for every nuclear power plant of Japan in 1995. (At a nuclear power plant disaster, then you? Hubou company)

The following is the prediction when the Hamaoka nuclear power plant No. 3 furnace (1,100,000kW of electric outputs) starts a nuclear core meltdown and their container is destroyed. U.S. Atomic Energy Commission calls this type of the accidents "BWR-2 type" and 1/5 of all radioactivities are emitted then.

The damage of the accident depends so much on the influence of the wind and weather conditions, and its weather conditions is assumed cloudy, 2m of wind velocity. In this case, radioactivity spreads at the angle of about 15 degrees to the lee.

1. Acute death

Fig 30
An acute obstacle will be encountered if someone is exposed to a lot of radiation. Fig. 30 expresses the death toll because of the acute obstacle. The predicted acute death toll is the united number of the numbers that are written in the cities, towns and villages within the sector of the 15 lees drawn on this figure.

If radioactivity flows in the direction of land, the number of the acute dead will become a 100,000 people scale in every direction. This is a number of the case that evacuating is impossible.

Notes 1. Nuclear power plant disaster calamity evaluation that the Japanese government performed

The nuclear-power-industry meeting that received consignment of the Science and Technology Agency performed the damage trial calculation by the accident in 1959 considering as a model the nuclear reactor of 160,000kW of electric outputs planned in Ibaragi Tokaimura those days.

When 1/50 of the radioactivity in a nuclear reactor is emitted, it is supposed that 720 persons die, 5000 have obstacles, and 4 million need important point observation at the maximum.

However, this is only the case by the acute obstacle. The late-coming obstacles and the heredity obstacles are exception and underestimate.

Moreover, compensation for the dead (850,000 yen), for removal expense (600,000 yen per a man in a city part, 350,000 yen per a man in a countryside, 100,000 yen for the refuge for 6 months), for the farming damage etc. Totally it is estimated at 3,700 billion yen in the amount of money of those days.

So they decided that the compensation for a nuclear power plant disaster would make 6 billion yen a maximum noting that its damage exceeds the compensation capability of an electric power company too far.

2. Late-coming obstacle
Fig 31

Our genes get damaged and cancer and some heredity obstacles will also show as the symptoms even with the radiation that does not cause an acute obstacle in dozens of years or several years. Fig. 31 is a prediction of the future cancer death toll according to various direction of the wind at the same accident.

When radioactivity spreads in the northeast direction in a metropolitan area, the future cancer death toll is predicted to be 4,340,000 people. If it goes in the west direction of Nagoya, it will become 2 million people. When it spreads in the north direction of Shinshu, since there is little population, the cancer death toll becomes about 400,000 people. It is also a number at the time of not emigrating for five years or more.

Notes 2. Evaluation of a late-coming obstacle

About the contamination dose of radiation, the late-coming obstacle or the heredity obstacle, the estimate is different by the researcher. The late-coming obstacles are the future leukemia by a gene getting damaged; development of symptoms of cancer, and the heredity obstacles that are the influences on the posterity by the damage of the productive cells. Here, the estimate by Dr. Goffman is used.

The cancer death toll generated per 10,000 people.

Evaluator (year)

Cancer death toll



U.S. science academy(1980)






The Radiation Effects Research Foundation(1987)


U.N. radiation influence committee(1988)


U.S. science academy(1990)





3. Habitation Impossible Area by Long- Life Radioactivity

Fig 32

Fig. 32 shows the range of the area where the habitation becomes impossible semi permanently because the ground is polluted by long-life radioactivity like cesium 137 (half-life 30 years) in a same accident and the same climate conditions, and when it becomes on the lee.

In the range of the sector of 15 degrees of lees, people should leave from a nuclear power plant to more 320km far away. In this diagram the sector of 15 degrees is drawn in the direction of north.

The loose refuge standard (inside of an small circle) depends the removal standard (40curie per square kilometer) of the Soviet Union by the CHIERUNOVIRI nuclear power plant disaster, and the severe refuge standard (inside of an outside circle) on the removal standard (15curie per square kilometer) of the Bell Lucy republic.

However, the Soviet Union also changed it into the severe standard in 1991.

Fig 33

Fig. 33 is the actual pollution situation by radioactive cesium by the Soviet Union CHIERUNOVIRI nuclear power plant disaster that occurred in 1986. The position of CHIERUNOVIRI is united with Hamaoka and the Japanese Islands of the same scale are piled up.

The area colored purple is the pollution area to remove with more than 15curie (Ci) per square kilometer. The total area of the migration region specified by three nations; Ukraine, Bell Lucy and Russia is about 10,000 square kilometers, and it is approximately the same area size of united Shizuoka Prefecture and Yamanashi Prefecture. However, still now, 13 years after the accident the migration has not completed.

All the colored ranges are pollution areas of 1curie per square kilometer or more. In it, the radiation of the strength applicable to a radiation surveillance zone is released in Japan. The area 145,000 square kilometer, it is equivalent to 64% of Honshu in Japan.

Cesium 137's contamination to the ground brings about the external contamination from the gamma ray. When it shifts into crops, it is taken inside of the body and internal contamination is brought about.

As for cesium 137, also in six years after the accident, 70 to 99% has adhered to topsoil according to the investigation of the Bell Lucy National Universities. Since the half-life of cesium 137 is 30 years, the dose of radiation from the ground of 30 years after falls only to 9 to 48%. Of course, the radioactivity that crowded for the plant, spread in the earth, or flows away, continues releasing radiation at a movement place.

4. Cancer by the radioactivity of comparatively short life

The typical short life radioactivity is radioactive iodine. If iodine is taken in inside of the body, it will gather at the thyroid gland and will damage the cell's gene there. Especially the children of a growth phase have active thyroid gland so they get cancer very easily.

Radioactivity called iodine 131 decreases at a half rate in eight days. It decreases to 1/100 million within half a year. Therefore, the immediate refuge within half a year influences the future number of development of symptoms.

In order to protect from a nuclear power plant earthquake disaster

1. Weather conditions

A nuclear power plant calamity depends a lot on the weather conditions and distance. Accident information may not be transmitted in case of a big earthquake.

You have to prepare to able to choice the optimal action when the accident occurred, seeing the weather and wind, predicting the strength of the radioactivity and attainment time that comes to each place.

1-1 weather

The strength of the radioactivity that rides on a wind and flows changes with weather.
Type "A": Almost calm (2m of wind velocity) the daytime on a sunny day

Fig 35

As the ascending current is strong, the radioactivity is pressured upwards high up in the sky with large diffusion, and the radioactive cloud spreads widely thinly.
The angles of the transverse spread direction in surface of the earth are 40 degrees

Model "D": Cloudy, almost calm (2m of wind velocity) all day.

Fig 36

Diffusion is small.
The angles of the transverse spread direction in surface of the earth are 40 degrees

Type "F": At the night in winter, very chilly but cleared up, almost calm (2m of wind velocity)

Fig 37

Since radiative cooling makes the inversion layer, a radioactive cloud does not spread to the sky, but it flows crawling on the ground. It also spreads little in the transverse direction at the surface of the earth, and an angle is 7.5-degree, the width of radioactivity is narrow but reaches to a distant place without thinning.

Rainy weather

When some radioactive clouds pass by rainy spot, a lot of radioactivity with raindrops will fall. Getting wet to rain brings the worst result. If the radioactive cloud that flowed far away suits rain there, high concentration pollution spot will arise.

1-2 Wind direction

Fig. 38

Fig. 38 is the typical wind of summer in central Honshu. The wind from Hamaoka is blown to the Ina valley, the Kofu basin, and the Minami-Kantou area. The wind usually blows from the sea to land at daytime in summer and blows from land to the sea at night.

1-3 Wind velocity

The relations of the wind velocity and the attainment distance of radioactivity are mentioned in following explication. The attainment time of the radioactivity is presumed from wind velocity and the distance.

wind velocity 1 hour later 3 hours later 6 hours later 12 hours later
1m 3.6km 11km 22km 43km
2m 7.2km 22km 43km 86km
3m 11km 32km 65km 130km
5m 18km 54km 110km 320km
A radioactive cloud is a collection of the particles of radioactivity. It isn't black smog shown in a figure, white clouds, either. A radioactive cloud is not visible.
In order to know whether actually there is the radioactive cloud there, we can do it only by the radiation detector. (The damage residents of the Three Mile Island nuclear power plant accident have testified "A taste like metal was felt".)

2. Emergency evacuation
Fig. 39

At the Tokai earthquake, it is assumed that road is divided, information is not transmitted, and telephone cannot be used, either. If a radioactive cloud flows on it, relief will be definitely difficult.

The situation of a nuclear power plant disaster could not be grasped, either. it is dangerous that many persons escape all at once under such circumstances

We have to give priority to emergency evacuation for the people of the dangerous zone, where they receive an acute radiation injury if the immediate refuge does not take.

2-1 Emergency evacuation zone

Range of the area where we must evacuate immediately

Power Plant Number Weather Type A
Fine/Day/Wind velocity 2m
Weather Type D
Cloudy/Day & Night/Wind velocity 2m
Weather Type F
Winter/Fine/Night/Wind velocity 2m
1.2km~40‹ 11km~15‹ 22km~7.5‹
840,000 kw
1.8km~40‹ 17km~15‹ 34km~7.5‹
1,100,000 kw
2.4km~40‹ 22km~15‹ 44km~7.5‹
1,140,000 kw
2.5km~40‹ 23km~15‹ 46km~7.5‹
3,620,000n kw kw
8.0km~40‹ 72km~15‹ 145km~7.5‹
Using Mr. Ken Senoo's method, the range of the area where the acute injury contamination of 1Sv or more was caused when the immediate refuge does not take was calculated. Each case of the furnace No.1 to 4 has taken out.

Since I think we also have to need simulate about the worst case of the accident by the earthquake, the case of the accidents that happen at all the plants at the same time was calculated, too.

The figure shows the emergency evacuation area in the case of No. 1 (540,000 kw), No. 3 furnace (1,100,000 kw), and all the furnaces together (3,620,000 kw).

Respectively, the sector smeared away is an emergency evacuation area about the weather type "A", type "D", and type "F". The wind blow from south with the velocity of 2m.

When wind directions differed, it expressed with the concentric circle how far it would become an emergency evacuation area. Time for a radioactive cloud to reach was also shown at the time of 2m of wind velocity.

The emergency evacuation area in case of the big accident at No. 1 furnace Fig.40

The emergency evacuation area in case of the big accident at No. 3 furnace Fig.41

The emergency evacuation area in case of the big accident at all the furnaces


Although it seems that it flows to Minami-Alps also at the time of type "F" in the diagram, as long as watching the situation of usual smog, it is thought that it flows along the bottom of the Ina valley or the Kofu basin.

2-2 The method of emergency evacuation

When you are in an emergency evacuation area unfortunately, what should it carry out? There are some courses exposed you the radiation.
* Radiation from the particle of the radioactivity that drifts in the air
* Radiation from the particle of the radioactivity which descended on the ground
* Radiation from the particle of the radioactivity adhering to clothes or the skin
* Radiation from the particle of the radioactivity that entered into the body through breathing

So you should follow these prevention methods.@@

* Cover your mouth with two wet towel not to inhale radioactivity.
* Cover your body as much as possible with a hat or clothes.
* You have to take refuge to the right angle of the wind

However, in the case of rain, it is better to be indoor, since a lot of radioactivity was contained in the raindrop.

However, the building may have collapsed by the earthquake. The buildings to refuge from the rain enough may not remain. Moreover, since the earthquake the roads will not be able to use, you have to refuge walking. Any train and bus will not move at all.

When you come out of the acute death area, you have to exchange all of clothes or footwear and wash your body very carefully. This is called "decontamination." It is necessary to surely perform decontamination. It is fatal if radioactivity is put on.
The property only has to be abandoned. You have to ask the people of the area where you refuge to offer spare clothing. A car also must be abandoned if its inside is polluted.

If the radioactive iodine is crowded in your body, it gathers at the thyroid gland and damages its genes, and thyroid gland cancer will be caused about several years or ten years after.

Especially the children of a growth phase have the active thyroid gland, and tend to collect iodine. To prevent it, drinking some iodine tablet simultaneously with a contamination front or contamination is efficient not to receive excessive radioactive iodine in the thyroid gland.

The iodine tablet should be prepared only for the residents who live within less than several km areas from the nuclear power plant. However, in confusion of a big earthquake and emergency evacuation, I doubt whether it is really distributed.

In fact, although an iodine tablet is required also out of an emergency evacuation area, probably, it will be difficult to get.

Radioactivity called iodine 131 decreases to a half in 8 days, and to 1/100 million in half a year. Early correspondence influences the future onset of the thyroid gland cancer.

2-3 The allowance for the emergency evacuation people

In the adjoining land region of an emergency evacuation zone, you have to accept the refuge people. Decontamination work and bathing should be done immediately. It is necessary to prepare the spare clothing that is not polluted. Never makes them to wait for a long time.

Although it is thought that there are some public recreation institutions within the sphere of several 10km of a nuclear power plant, are there a sufficient number of institutions to use for the refuge? The exhaust port of the water used for decontamination is polluted and those institutions will become impossible to use any more. The polluted clothes need to be treated very carefully.

You have to treat to the person who has the acute injury condition. The hospital itself has damaged by the earthquake. You also have to carry out the allowance of the injury people.

The persons who were already exposed to a lot of radiation with an acute condition or not, they all need to take refuge to a distant place preferentially in order to prevent the further contamination. You have to convey them somehow to the place that you can get on the train.

3. The refuge area in several days

It is important not to inhale and not to touch radioactivity if possible even at the distant place from the emergency evacuation area. If there is an airtight good building that has not been damaged by the earthquake, you can take refuge there closing the door and window. However, the passage of a radioactive cannot be known without the radiation detector.

And besides that, the radioactive contamination from the ground is caused by the radioactivity that had descended. It is the same as an emergency evacuation area to cover the body with a hat or clothes and with the wet towels as much as possible. Don't carry indoors the clothes used outdoors. If the head is not damaged in the earthquake secure water as in large quantities as possible before radioactivity comes, and you can use only it after that.

It takes several days to one month for the contamination dose to reach to 1Sv that could cause the acute injury by the contamination of the ground. However, according to Goffman, with the contamination of a little less than 1Sv, the possibility of future cancer death becomes about 40%.

Therefore, the pregnant women, infants, and the childen have to take refuge in the area where radioactivity is not descending immediately. The people have to stay at the safe area about for half a year until the influence of radioactive iodine is lost. In case of the Chernobyl nuclear power plant disaster, the children of Kiev got used evacuated 130km over a long period of time.

On the other hand, you have to treat those who have escaped from the emergency evacuation area. You also have to offer transportation, in order to carry them to a distance place preferentially.

Next, the men and women of the certain age to builds a child after this should take refuge. After the refuge of the persons of the emergency evacuation areas, the rest of the people take refuge. An acute injury can be prevented; if this is completed in several days and they take refuge about for one month.

4. Removal area

Even after radioactive iodine with a comparatively short life disappears, contamination by the long life radioactivity remains. The main one is the cesium 137 and strontium 90 whose half-life is about 30 years.

Although an acute injury does not come out by that radioactivity, habitation becomes impossible with the danger of the future cancer death from late-coming injury. Especially an embryo tends to be influenced by radioactivity so much that the miscarriages and stillbirths are increasing in the stricken area of the Chernobyl accident through the radiation from the ground, and the contamination of mother's body.

The lee distance from which cancer death becomes more than 20% (contamination dose of 0.5Sv or more) when you did not emigrate for more than five years was calculated in each weather conditions and the nuclear power plant.

Power Plant Number Weather Type A
Fine/Day/Wind velocity 2m
Weather Type D
Cloudy/Day & Night/Wind velocity 2m
Weather Type F
Winter/Fine/Night/Wind velocity 2m
9.5km~40‹ 86km~15‹ 170km~7.5‹
840,000 kw
15km~40‹ 130km~15‹ 270km~7.5‹
1,100,000 kw
19km~40‹ 180km~15‹ 350km~7.5‹
1,140,000 kw
20km~40‹ 180km~15‹ 360km~7.5‹
3,620,000n kw kw
63km~40‹ 580km~15‹ 1200km~7.5‹

The area of 20% cancer death possibility by long-life radioactivity was shown in the figure about the case of No. 1 (540,000 kw), No. 3 (1,100,000 kw), and all plants (3,620,000 kw). The sector smeared away is the area of 20% cancer death possibility about the weather type "A", type, "D" and type "F" respectively. The wind blows from south with the velocity of 2m. When wind directions differed, it expressed with the concentric circle how far it would become the area of 20% cancer death possibility.

The area where the 20% people die by cancer when the accidents occur at No.1 plant

Fig. 43


The area where the 20% people die by cancer when the accidents occur at No.3 plant


Fig. 44

The area where the 20% people die by cancer when the accidents occur at all the plants

Fig. 45

In fact, the wind may change in the middle of radioactivity discharge. If it rains locally, a high concentration pollution area will be made.

Look at the cesium 137 pollution map by the Chernobyl accident. The "hot spot", which has very high concentration contamination, was made especially in a place where the water was flowed and covered. Such a place is the ban on entry severely.


5. Rescue operations.

@Many young men rushed for relief in the Hyogo southern part earthquake or the Nakhodka crude-oil outflow. However, it is impossible at a nuclear power plant earthquake disaster.

It is impossible to enter in a radioactive contamination area except those who equipped specially for it, and they also need to be ready for remarkable contamination.

In the Chernobyl accident, many young soldiers are mobilized and many of them died or got troubles of the sequela. I cannot consider that there are the sufficient equipment and sufficient training and manual in the fire fighting, the police, the Self-Defense Forces in Japan to carry it out.

In fact they themselves also have to go away from the stricken area, treating those who have escaped from the stricken area, and sending them out to the distant place.

Each of us must consider how it is possible to carry a lot of people to a distant place with the least confusion.

The people of an emergency evacuation area will have to take refuge, rescuing the injured by the earthquake. The people of the adjoining land region has to evacuate the pregnant women, infants, children and the victims of the earthquake, they also have to evacuate from the emergency evacuation area.

Depending on the grade of radioactive contamination, they will also have to take refuge within several days. From how far will be the adjoining land region changes with the scale of the accident and weather conditions. It is better to think it'll be until the place far from the emergency evacuation area with several times of its dimension.

Acceptance of a lot of nuclear power plant earthquake disaster refugees is required in the area where radioactivity did not reach. I want to young volunteer men to play an active part there.

6. Radiation detector

A radiation detector is required in order to know invisible passage of the radioactive. There are some kinds according to a use.

1.The type that catches weak radiation of previous announcement of radioactive cloud. (Non-portable type)

2. The type that confirms whether decontamination was completed. (Ordinary carried type)

3. The type that measures the long-term pollution situation of ground.

4. The type that measures radioactivity in food.

(1.) and (2.) are needed for an emergency.



Please refer to this URL for details. (Japanese)