#Fukushima I Nuke Plant May Still Be Leaking 8 to 93 Billion Becquerels Per Day into Ocean, University Researchers Say

"See, just like I've always thought!" is a reaction from Japanese people on Twitter. "Finally they are saying it openly" is another.

Anyway, from NHK News (3/15/2013; part):

東京電力福島第一原子力発電所の専用港で、海水の放射性セシウムの濃度がほとんど下がらなくなっていることについて、東京海洋大学の研究グループが試算したところ、汚染水の流出が止まったとされるおととし６月以降も、１年間で事故前の排出限度の７３倍に当たる放射性セシウムが専用港に流れ出た可能性があることが分かりました。研究グループは、詳細な調査を実施すべきだ、としています。

The density of radioactive cesium in the seawater inside the harbor at Fukushima I Nuclear Power Plant has stopped going down for some time. According to the estimate by a group of researchers at Tokyo University of Marine Science and Technology, it is possible that radioactive cesium in the amount 73 times as large as the discharge limit before the accident may have leaked into the water in one year since June 2011, when the leak of contaminated water is supposed to have stopped. The group says the detailed research is necessary.

東京海洋大学の研究グループは、福島第一原発の専用港で海水に含まれるセシウム１３７の濃度が、去年春以降、高いところで、国の基準を上回る１リットル当たり１００ベクレル前後からほとんど下がらなくなっていることから、原因の究明に役立てるため独自に試算を行いました。

The research group at Tokyo University of Marine Science and Technology did its own calculation in order to figure out why the density of cesium-137 in the seawater inside the Fukushima I Nuke Plant harbor has remained at about 100 becquerels/liter since spring of 2012, higher than the government standard.

試算では、専用港の海水は、海流や潮の満ち干で１日に４４％が入れ替わると推定され、セシウム１３７が公表されている濃度になるには１日当たり８０億から９３０億ベクレルが流れ込んでいる計算になる、としています。

According to the calculation, 44% of seawater inside the harbor is replaced by the current and the tides in one day. In order for the cesium-137 density to be what is published, 8 to 93 billion becquerels [of cesium-137] per day must be flowing into the harbor.

その結果、汚染水の流出が止まったとされるおととし６月以降の１年間では、事故前の保安規定で定められた排出限度の７３倍に当たる１６兆１０００億ベクレルが専用港に流れ出た可能性がある、ということです。

As the result, in one year from June 2011 when the leak of contaminated water is supposed to have stopped, 16.1 terabecquerels [of radioactive cesium], or 73 times as much as the discharge limit set by the safety regulation before the accident, may have leaked into the harbor.

... これに対し東京電力は「さまざまな調査の結果から、発電所の敷地から放射性物質が海に流出しているとは考えていない。ただ、専用港の海水で放射性セシウムの濃度が下がらない原因は分かっていないので調査を続けたい」と話しています。

TEPCO says, "We don't think radioactive materials is leaking from the plant compound to the ocean, based on the various surveys done. However, we don't know the reason yet as to why the density of radioactive cesium in the seawater inside the harbor is not decreasing, so we want to continue the investigation."

To put these numbers in perspective in post-Fukushima Japan, Yomiuri Shinbun and other media reported in November 2011 that 52.5 billion becquerels of radioactive cesium were being discharged into the ocean every day by Abukuma River that flows through Fukushima Prefecture.

The estimated amount of radioactive cesium discharged/leaked from Fukushima I Nuclear Power Plant into the ocean from March 26 to September 30, 2011 (TEPCO's estimate):

• Cesium 134: Approx. 3.5x10^15 Bq (or 3,500 terabequerels, or 3,500,000 billion becquerels)

• Cesium 137: Approx. 3.6x10^15 Bq (or 3,600 terabequerels, or 3,600,000 billion becquerels)

A greenling caught inside the harbor of Fukushima I Nuclear Power Plant on February 17, 2013 was found with 510,000 becquerels/kg of radioactive cesium, highest ever tested in fish since the start of the nuclear accident.

Aside from probable bioconcentration / bioaccumulation, strontium-90 in the water inside the plant harbor hasn't dropped down much either.

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