radiation levels these one and a half months in Tokyo

date	Environmental radiation levels	Radioactive material level in tap water			Radioactive material level of fallout			Remarks
	μGy/h	131I Bq/kg	134Cs Bq/kg	137Cs Bq/kg	131I Bq/m2	134Cs Bq/m2	137Cs Bq/m2
04-29	0.0677	0.22	ND	ND	ND	ND	ND
04-28	0.0688	0.14	ND	ND	ND	ND	ND
04-27	0.0693	0.29	ND	ND	ND	ND	39	rain
04-26	0.0694	ND	ND	ND	ND	5.4	6.6
04-25	0.0697	0.24	0.32	ND	ND	ND	5.5	rain
04-24	0.0701	0.36	ND	ND	ND	5.0	5.4
04-23	0.0714	0.30	0.20	ND	ND	ND	ND	rain
04-22	0.0722	0.36	0.20	0.21	ND	ND	ND	rain
04-21	0.0723	0.26	ND	ND	ND	4.2	5.8
04-20	0.0728	0.19	ND	ND	20	19	21	rain
04-19	0.0754	0.29	0.21	ND	ND	26	30	rain
04-18	0.0752	0.22	0.21	ND	56	ND	ND	rain
04-17	0.0753	0.20	ND	ND	ND	13	15
04-16	0.0761	0.30	ND	ND	ND	4.3	6.3
04-15	0.0767	0.30	ND	ND	ND	5.1	4.8
04-14	0.0776	0.41	ND	ND	ND	ND	ND
04-13	0.0777	0.41	ND	0.26	ND	ND	ND
04-12	0.0777	0.57	ND	ND	ND	ND	4.0
04-11	0.0837	0.60	ND	0.27	100	160	170	rain
04-10	0.0827	0.71	ND	ND	3.0	4.1	5.2
04-09	0.0839	1.0	ND	0.26	19	4.5	7.9	rain
04-08	0.0848	0.89	0.24	0.24	8.9	10	12
04-07	0.0861	1.4	0.32	0.24	5.3	ND	ND
04-06	0.0873	1.6	0.29	0.21	6.2	9.9	10
04-05	0.0884	2.6	0.32	0.32	8.2	7.0	5.6
04-04	0.0895	3.8	0.32	0.27	17	5.2	5.9
04-03	0.0908	2.9	0.21	0.29	20	18	18
04-02	0.0947	2.0	ND	0.45	ND	4.0	8.0
04-01	0.0971	2.1	ND	0.45	ND	9.1	15
03-31	0.100	3.4	0.35	0.53	38	19	26
03-30	0.104	5.1	0.26	0.64	50	66	68
03-29	0.107	5.6	ND	0.51	21	ND	5.4
03-28	0.111	9.8	0.26	0.56	37	10	18
03-27	0.116	20	0.47	0.73	46	ND	5.5
03-26	0.122	37	0.78	1.0	100	31	36
03-25	0.130	32	0.92	1.2	220	13	12
03-24	0.137	26	1.0	1.4	170	34	37
03-23	0.146	26	0.62	0.87	13000	130	160	rain
03-22	0.137	19	0.34	0.31	36000	330	330	rain
03-21	0.0969	5.3	0.23	0.22	32000	5300	5300	rain
03-20	0.0457	2.9	ND	ND	2900	550	560	rain
03-19	0.0467	2.9	0.15	0.21	40	ND	ND
03-18	0.0484	1.5	ND	ND	51	ND	ND
03-17	0.0511
03-16	0.0719
03-15	0.109 (max 0.809)	the first wind from the exploded nuclear plant to Tokyo
03-14	0.0341
03-13	0.0343
03-12 (explosion)	0.0342
03-11	0.0341
03-10	0.0338
03-09	0.0343
03-08	0.0343
03-07	0.0366
03-06	0.0343
03-05	0.0339
03-04	0.0339
03-03	0.0340
03-02	0.0344
03-01	0.0368

clean my room operation. wipe, wash, scrub

The fallout has reduced. A professional said it a time to clean the fallout. I am going to clean my room, with opening the window. Let's wipe Wall, floor, louver and everything one by one.

I am afraid that invisible cake of radioactive dust stick on the shoes.
I need new hight top sneakers :)

monju

Monju is a reactor under suspension because of accident.
It is an asset of Japan Atomic Energy Agency(http://www.jaea.go.jp/), which is a special government agency; independent administrative institution.

Monju is a experimental reactor. It is a Fast Breeder Reactor(FBR) and its coolant is Na. I don't know what it means.

One device (3.3t) in the reactor fell at August 26th 2010, still no way has been found to fix it. This reactor's maintenance cost is said 55,000,000 yen per day (460,000 $/day). I do know what it means.

tomodachi operation

I am writing this because my American friends did not know about tomodachi operation. I just wanted to say thank you.

This operation is not for the nuclear problem. It is for devastating tunami. Tomodachi operation by American marine started shortly after the disaster by tunami was found. The tunami was too fatal, too ruinous to know what happened because disaster victims had lost their communications. Japanese government don't know how many ppl are killed still now. The ships came to devastating coastal area quickly, and flied helicopters, found isolated villages and sent food and water. After that, marine rebuilt the wrecked air port by tunami only a few days, make the school ground available, and wipe away the tons of rubble.
I don't know a detail about tomodachi operation. But I am impressed by what highly skilled and well disciplined organization with advanced technology has done.

This operation was completed and they left the coast.
I saw a school boy asked marines their autographs on TV news.

Their activity was done more than 80km away from Fukushima nuclear plants.
Many Japanese are living within 30km area because Japanese government announced that evacuation was on a voluntary basis. But Japanese government changed their policy recently and is planning to have residents in highly contaminated area evacuate within one month.

internal exposure

When radioactive foods are eaten, they emit radiation inside our body, it is called internal exposure.
Interim guideline about radioactive materials on food was announced 17th March.
http://www.mhlw.go.jp/stf/houdou/2r9852000001558e-img/2r98520000015av4.pdf

Each limit value varies depending on radioactive material type and food type. For example, limit of radioactive iodine on vegetable is 2000Bq/kg, limit of "Alpha-emitting nuclides of plutonium and transuranic elements" on infant foods is 1Bq/kg. (lol plutonium guideline on infant foods.)

To say the truth I was at loss because I did not understand how dangerous or how safe these numbers were.
As I knew too little, I ate much banana, because all banana in Japan is imported form clean countries. And I read banana abounds radioactive thing just now. haha.

http://www.who.int/foodsafety/fs_management/INFOSAN_note_Radionuclides_and_food_300311.pdf

Banana is one of the potassium rich produce, like milk, and 0.0117% of all potassium in natural is potassium-40 which is radioactive. Banana is said to have several hundreds Bq/kg. As human body includes a lot of potassium also, human itself has 6000-7000Bq.

Unit "becquerel(Bq)" is kind of amount of radiation, unit "sievert (Sv)" shows how much human being is effected. Above WHO document shows how to calculate unit becquerel to sievert. When someone eat 300g vegetable which contain 2000Bq/kg iodine-131 and 500Bq/kg cesium every day, total amount of internal exposure after one year is (these are maximum value of interim guideline):

iodine-131
0.3(kg) * 2000(Bq/kg) * 0.00018(mSv/Bq) * 356 = 38.448 (mSv)

cesium
0.3(kg) * 500(Bq/kg) * 0.000013(mSv/Bq) * 356 = 0.6942 (mSv)

I agree that as the interim guideline is a interim thing, one year might be unexpected term.
But I eat not only vegetable but also grain, fruit, egg etc. I drink water too.
I will struggle to find lower radioactive foods for a while. I hope it will be a "for a while" problem.


Please confer above number to following dose limits:
http://www.euronuclear.org/info/encyclopedia/r/radiation-exposure-dose-limit.htm

today's environmental radiation level

These day's environmental radiation level in Tokyo is the same of that of Beijing

Beijing 78.4 nGy/h (average 2011/04/14 9:00-15:00)
Tokyo 77.6 nGy/h (average 2011/04/14)

No iodine-131 or cesium-137 in fallout was detected at 14th April.
Radioactive material level in tap water is acceptable level according to WHO guideline.
I was happy to know these data this morning.


Beijing's data url:
http://haq.mep.gov.cn/gzdt/201104/t20110415_209246.htm

Tokyo's data url:
http://ftp.jaist.ac.jp/pub/emergency/monitoring.tokyo-eiken.go.jp/monitoring/hourly_data.html
http://ftp.jaist.ac.jp/pub/emergency/monitoring.tokyo-eiken.go.jp/monitoring/w-past_data.html
http://ftp.jaist.ac.jp/pub/emergency/monitoring.tokyo-eiken.go.jp/monitoring/f-past_data.html


But it does never mean tokyo become free from radioactive contamination.
For example, The measuring device which is used to measure above tokyo data looks equipped on the roof of the building according to the photos. It is said that radioactive materials are fallen on the ground gradually. I hear some data which are sampled near ground shows higher number than above number. This means small children or dogs would be effected much more than adult.

And it was not only iodine-131 and cesium-137 that leaked from Fukushima nuclear plant.

By the way, when the fist testing result of fallout on the nuclear plant ground was announced, I heard very curious words. "Plutonium was detected in 2 samples, they were thought to be from the accident, other 3 samples included the plutonium too, these were average level for ground." Common quantity level of plutonium? Plutonium is one of the most feared isotope to Japanese. A few days after this announce, I heard that they were legacy of '60, cold war encourage nuclear development and nuclear bomb test. Half-life of Plutonium-239 is 24,000 yeas.

Half-life of iodine-131 is 8.1 days. So if Fukushima nuclear plant stop leaking, iodine-131 will disappear soon. But even if Fukushima nuclear plant stop all of nuclear leaking asap, many long half-life radioactive things will remain and spread to the food.

so many aftershocks... really aftershock?

these several days, relatively small magnitude earthquakes has been occurring over and over. The epicenters are near the nuclear plant.

Seismologists on TV explain about aftershocks. But I wonder who simply accept their talk; these are natural aftershocks of 3.11 earthquake.