#Fukushima Prefecture Installs Fixed Radiation Monitoring Posts, Radiation Levels Drop by Half

Talk about retarded. Fukushima Prefecture replaces portable radiation monitoring posts with fixed ones on April Fool's Day, and one of the local newspaper dutifully reports the results of the new measurement.

Surprise! Radiation levels dropped by half, using the fixed monitoring posts! The radiation level in Koriyama City went from 0.51 microsievert/hour on March 31 to 0.26 on April 1!

Even the Fukushima local residents thought the numbers were suspicious. It turns out that the fixed monitoring posts were installed at locations that had been just "decontaminated", and the measuring unit was changed from sievert to gray.

First, the local newspaper Fukushima Minyu on April 2, 2013, whose article gives an impression that it was because of the "portable" (temporary) nature of the monitoring posts that were giving elevated radiation numbers, with no mention of decontamination or change of measuring unit:

主要定点「モニタリングポスト」、６方部を固定型に

Major "monitoring posts" in 6 regions replaced to fixed type

県は１日、主要定点の放射線量として県内７方部に設置したモニタリングポストのうち、６方部のポストを持ち運びができる可搬型から固定型に取り換えた。

On April 1, the prefectural government replaced the portable radiation monitoring posts in 6 regions out of 7 regions in the prefecture with the fixed ones.

この結果、各地の空間放射線量の測定値は、郡山が交換前（３月３１日）の毎時０．５１マイクロシーベルトから０．２７マイクロシーベルト、南相馬は毎時０．３マイクロシーベルトから０．１４マイクロシーベルトにほぼ半減するなど全体的に下がった。

As the result, the air radiation levels measured in these 6 regions generally dropped lower. In some cities the radiation dropped almost by half; the radiation level in Koriyama City went from 0.51 microsievert/hour on March 31 before the replacement to 0.27 microsievert/hour, and the radiation level in Minamisoma City went from 0.3 microsievert/hour to 0.14 microsievert/hour.

特に数値が下がった郡山はポストの位置を約８０メートル、南相馬は約４５メートル移した。県は設置場所を固定するため電源の位置や施設の利用に支障が出ない場所、県民の目に触れやすい道路近くを選んだとしている。

Koriyama City, which saw the radiation level drop significantly, moved the location of the monitoring post by 80 meters [from the original location]. Minamisoma City also moved the location by 45 meters. According to the prefectural government, the new locations were selected so that the power supply for the monitoring posts was secure and that the access to public facilities wouldn't be hindered. The new locations are also close to the roads so that the monitoring posts can be easily seen by residents.

Residents, many of whom have been using their personal survey meters since the accident, are skeptical. FNN Local News reported on April 2, 2013 that radiation levels as measured in Koriyama City got significantly lower in one day. Its reporter spoke with the government official, and found out that, in addition to installing the fixed monitoring posts in locations that just got decontaminated, they also changed the unit of measurement from microsievert/hour to microgray/hour, shaving off 20% in numbers:

福島県は、ウェブサイトで、県内7カ所の空間放射線量を公開している。県中地区の放射­線量を3月26日から示したグラフでは、午後3時の値を見ると、およそ0.5マイクロ­シーベルト(μSv)で推移していたが、1日から0.27と、およそ半分になった。こ­の変化をめぐって、県に問い合わせが相次いでいる。

Fukushima Prefecture publishes the air radiation levels in 7 locations inside the prefecture on its website. The chart that plots the radiation level in Mid Prefecture District from March 26 shows 0.5 microsievert/hour at 3PM, until April 1, when it dropped by half to 0.27. Many residents are asking the prefectural government about this change.

福島県が県中地区として公表している放射線量を測定しているのは、郡山市麓山(はやま­)にある郡山合同庁舎。

Fukushima Prefecture measures the radiation level for Mid Prefecture District at Koriyama Common Government Building in Hayama district of Koriyama City.

郡山市の空間放射線量の値として、これまで公表されていたのが、可搬型のモニタリング­ポストで計測されたもので、手元の線量計で確認すると、毎時0.4マイクロシーベルト­を超えていた。

The air radiation level of Koriyama City as published [by the prefectural government] had been measured by a portable monitoring post [before April 1]. When we checked with our survey meter, the radiation level was over 0.4 microsievert/hour.

3月31日までは、この可搬型モニタリングポストの数値が、県中地区の放射線量として­公表されてきた。

Up until March 31 this year, the number at this portable monitoring post was published as the radiation level for Mid Prefecture District.

しかし1日からは、およそ80メートル離れた場所に設置された固定型モニタリングポス­トの数値が公表されている。

However, starting April 1, the number at the fixed monitoring post installed at a location 80 meters away from the portable monitoring post has been used.

県中振興局の鈴木 仁副部長は「(低くなっている一番の理由は?)これは、舗装面で風がずいぶん当たって­いた場所だし、せっかくの施設(設備)なので、設置する前に、ここの一角だけは除染し­た」と話した。

(When we asked what contributed most to the lower number,) Hitoshi Suzuki, Deputy General Manager of Mid Prefecture District Development Bureau, said "This location [new location] is on a paved surface exposed to wind. Since we were installing brand-new monitoring post, we decontaminated the corner on which the monitoring post was to be installed."

固定型モニタリングポストが設置されたのは、すでに除染が行われた場所だった。

So, the fixed monitoring post was installed on a spot that had been decontaminated.

また、鈴木副部長は「物理量として測っているのはグレイ、人体に与える影響に換算した­のがシーベルトです。(より低く出るのは、グレイで測っているから?)そうですね。そ­の差っていうのも、今回は出ている。シーベルトからグレイになったっていうことで」と­話した。

Mr. Suzuki also said, "Gray measures physical quantity of radiation, and sievert measures the effect of radiation on human bodies". (We asked, "Is the lower number from measuring in gray?") "Well, that difference is shown this time, [with measuring unit going from] sievert to gray."

発表する単位を変更したことも、要因の1つだという。これまで、「マイクロシーベルト」だった単位を、1日から「マイクログレイ」に変更し­たことで、数字上は20%低くなる計算。

So, changing the unit in which the number is published has contributed to the lower number. By changing from "microsievert" to "microgray" starting April 1, the number is estimated to get lower by 20%.

鈴木副部長は「市民・県民に目立つ場所に置いて、長らく使う施設になるだろうし。庁舎­の敷地の中で、一番いい場所かなと思って、考えて決めた」と話した。

Mr. Suzuki said, "We thought it was the best location in the Government Building compound, as residents can see easily and it is a facility to be used for a long time."

南相馬合同庁舎でも、毎時0.30マイクロシーベルトから、毎時0.14マイクロシー­ベルトに半減している。

At the Minamisoma Common Government Building, the radiation level has dropped from 0.30 microsievert/hour to 0.14 microsievert/hour.

福島県では、問い合わせに対しては、きちんと誠意を持って対応するとしている。

Fukushima Prefecture says the government will respond to residents' queries properly and sincerely.

Properly and sincerely. Here's very bureaucratic-sounding Mr. Suzuki, in FNN News, explaining how they decontaminated the site before installing the monitoring posts:

The entire FNN news clip:

Tweet

(UPDATED) Stanford Researchers Found Radioactive Cesium of #Fukushima Origin in Pacific Bluefin Tuna Off California Coast

(UPDATE) The paper as posted in the Proceedings of the National Academy of Sciences (PNAS):

http://www.pnas.org/content/early/2012/05/22/1204859109.abstract?sid=92ce1d87-a1c1-4fd4-a674-2db99d7bf957

(H/T karl)

=====================================

The researchers from Stanford University, California caught 15 tuna fish off the coast of southern California last August and measured radioactive cesium-134 and -137. Nine months later, it is in the news now that their research paper has finally been published in The Proceedings of the National Academy of Sciences.

Neither the Wall Street Journal article below, or Reuters', mentions the exact numbers for radioactive cesium, but Japan's Kyodo News does:

Cesium-134: 4 Bq/kg
Cesium-137: 6.3 Bq/kg

The Stanford researchers think the fish were in the Japanese water about a month after the accident started. Daniel Madigan, who led the study, said they were surprised to find cesium at all, and that it was found in all samples they collected and tested.

Wall Street Journal says the added radioactivity is about 3% of the naturally occurring radioactivity in the fish, and Reuters converts becquerels into curie to put things in perspective saying "It takes 37 billion becquerels to equal 1 curie".

Well, at least the Japanese media, MSM or alternative, has gotten comfortable over the last year quoting the measured numbers instead of trying to put them in perspective without mentioning the numbers.

From Wall Street Journal (5/28/2012; emphasis is mine):

Tuna Carried Fukushima Radioactivity to U.S. Coast

By ROBERT LEE HOTZ

Pacific bluefin tuna migrating last year from coastal Japan to the waters off Southern California contained radioactive cesium isotopes from the Fukushima nuclear disaster, scientists reported Monday.

The amount of radioactivity in the fish was one-tenth the level the U.S. and Japan consider dangerous, and likely posed no public health hazard or risk to people who ate the seafood, the scientists said. But the study showed for the first time that migrating sea life rapidly brought traces of radioactive elements from the damaged Fukushima Daiichi nuclear reactors across vast distances.

"The tuna packaged it up and brought it across the world's largest ocean," said marine ecologist Daniel Madigan at Stanford University, who led the study team. "We were definitely surprised to see it at all and even more surprised to see it in every one we measured."

Their findings raise the possibility that other wide-ranging sea-life that foraged near Japan, such as turtles, sharks and seabirds, may also have carried low levels of radioactive cesium from the accident around the Pacific basin. The scientists expect to conduct more tests on migrating bluefin tuna as well as albacore tuna, sea turtles, and several shark species this summer.

Their research was published Monday in The Proceedings of the National Academy of Sciences.

Prized as a sushi delicacy in Japan and around the world, Pacific bluefin tuna spawn in the Sea of Japan, among other locales. As they grow, the fish usually travel around the southern tip of Japan and follow the Kurishio Current up the country's east coast, past the scene of the nuclear accident, before migrating over 6,000 nautical miles to the eastern Pacific. The fish eventually return to their birth waters to spawn.

In their study, Mr. Madigan and his colleagues tested tissue from 15 young Pacific bluefin tuna caught by recreational fisherman off the coast of San Diego in August 2011, about five months after an earthquake and a tsunami severely damaged the Fukushima reactors, triggering the largest known accidental release of radioactivity into the ocean.

For weeks after the accident, levels of radioactivity were up to 10,000 times normal in the coastal waters off eastern Japan, where the bluefin tuna spend their early life before migrating across the ocean.

In the young bluefin tuna that reached California, the researchers found slightly elevated levels of cesium-137 and cesium-134, two primary products of nuclear fission that tend to concentrate in muscle tissue. The amount of cesium 137 was five times as much as the background level, leftover from nuclear weapons testing decades ago. Prior to the Fukushima accident, cesium-134, which has a half-life of about two years, was undetectable in seawater or marine life.

Overall, the levels were just enough to raise the naturally occurring radioactivity of the fish by about 3%, the scientists said.

"We found that absolutely every one of them had comparable concentrations of cesium-134 and cesium-137," said marine biologist Nicholas Fisher at Stony Brook University in New York state, who was part of the study group. "It is crystal-clear data."

For comparison, the researchers also tested tissue from yellowfin tuna caught at the same time last August and tissue preserved from bluefin tuna caught in 2008, three years before the nuclear accident. Yellowfin tuna typically spend their entire lives in the sea off the coast of California.

In both the yellowfin and the tissue of the 2008 bluefin, the scientists didn't find any cesium-134 and detected only the expected background levels of cesium-137.

Write to Robert Lee Hotz at sciencejournal@wsj.com

Tweet