Tellurium-132 Detected At 4 Locations On March 12 Before Fukushima Explosion That Day

#Fukushima I Nuke Accident Tellurium-132 Conundrum: Case of Missing Iodine and Cesium (EX-SKF, June 6, 2011):

This blog posted on June 3 that the Nuclear and Industrial Safety Agency revealed tellurium-132 had been detected 6 kilometers from the plant on the morning of March 12, before the venting of the Reactor 1.

Well, that Yomiuri Shinbun article in that post was incomplete, to say the least. It turns out that it was not only one location in Namie-machi where radioactive tellurium was detected but also at 3 other locations: one more location in Namie-machi, one location in Okuma-machi, and one location in Minami-Soma City.

Moreover, the same air radiation survey done by Fukushima Prefecture detected more volatile iodine-131 at half as much as tellurium, but it hardly detected any cesium-137 except at one location.

It’s not supposed to happen that way, if what we’ve been told about the circumstance is correct, as a Kyoto University professor says in the article in Tokyo Shinbun, below.

(I’ll go look for the information at NISA, and update if I find more data.)

Tokyo Shinbun (6/5/2011; emphasis added) reports the puzzling detection of tellurium-132 on March 12:

東日本大震災の発生翌日、福島第一原発で爆発が起きる前に福島県が行ったモニタリング調査で、金属性で飛散しにくい放射性のテルルが原発から約七 キロ離れた同県浪江町などで検出されていたことが分かった。拡散しやすい揮発性の放射性ヨウ素より多く検出されており、早い段階で金属性の放射性物質が広 く飛散していた。テルルはレアメタル(希少金属)の一種で、放射性同位体のテルル132の半減期は三日余り。主にベータ線を出す。

It has been revealed that radioactive tellurium, a metal that is hard to disperse in the atmosphere, was detected on the next day [March 12] of the earthquake in Namie-machi, 7 kilometers from the plant, and other locations according to the result of the monitoring survey done by Fukushima Prefecture before the explosion at Fukushima I Nuclear Power Plant that day. More tellurium was detected than more volatile radioactive iodine. It shows that metallic radioactive materials [like tellurium] dispersed wide from an early stage [of the accident]. Tellurium is a rare metal, and tellurium-132 has a half-life of about 3 days, emitting beta rays.

データは保安院が三日夜に公表。三月十二日朝から十三日夜までの大気を調べたもので、大半がこれまで未公表だった。テルル132は十二日朝から昼 すぎにかけ、浪江町の二カ所と大熊町、南相馬市で検出。濃度は一立方メートルあたり法定限度の二〇ベクレルを超える一一九~二三ベクレルだった。

The data was revealed on June 3 evening by the Nuclear and Industrial Safety Agency. The monitoring survey of the air was done from March 12 morning till March 13 night, and the most of the data had been withheld until June 3. Tellurium-132 was detected from the morning till the early afternoon on March 12 at 2 locations in Namie-machi, and Okuma-machi and Minami-Soma City. The concentration was between 23 to 119 becquerels per cubic meter, exceeding the safety limit of 20 becquerels per cubic meter.

当時の原子炉建屋は換気装置が止まり外に空気が出ない状態。蒸気を放出するベント作業は十二日午後に行われ、その直後に水素爆発が起きた。

At that time, there was no air escaping the reactor building as the air exchange system had stopped. The venting to release the steam was done in the afternoon of March 12, and a hydrogen explosion [in the Reactor 1] happened after the venting.

東京電力は、核燃料の損傷が最も進んでいたとされる1号機が漏出元とみており、「格納容器内の圧力が高まり、接ぎ目から水素とともにテルルが漏れ出したのでは。建屋内の圧力も高まって外に漏れ、風に乗って広がったことが考えられる」と説明している。

TEPCO thinks that tellurium came from the Reactor 1 whose fuel core was most damaged, and explains, “As the pressure inside the Containment Vessel rose, tellurium, along with hydrogen, may have escaped from the joints [on the Containment Vessel]. The pressure inside the reactor building also rose, and then tellurium leaked outside the building and was carried by the wind and spread wide.”

ただ、拡散しやすい揮発性のヨウ素131の検出量はテルルの半分程度。テルルと同じ金属性のセシウム137は浪江町の一カ所でテルルを上回った以外、微量しか検出されなかった。

However, volatile and therefore more easily dispersed iodine-131 was detected at half the amount of tellurium. Cesium-137 was detected in one location in Namie-machi in the amount exceeding that of tellurium; however, at other locations, it was detected in only minute amount.

京都大原子炉実験所の山本俊弘准教授(原子炉物理)は「現在分かっている状況では、テルルが遠方に飛散することは考えにくい」と述べた。

Associate Professor Toshihiro Yamamoto of Kyoto University Research Reactor Institute (reactor physics) says “Under the circumstance that we have understood so far, it is hard to believe that tellurium would spread far.”

Well it apparently did, Mr. Yamamoto. Now what?

(I guess the answer is “So what?”)

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