Posted by: Airtower | 2012-10-22

That’s Not Bad News

Time and time again I get annoyed at how the German media report on the Fukushima Daiichi nuclear disaster. Reports are frequently imprecise in a way that exaggerates dangers, while positive developments tend to go unreported. Here’s a recent example from WDR 5, a public radio station in Germany.

On September 26, TEPCO created an opening through the X100B penetration into reactor 1 and subsequently inserted various measurement tools. Among other things, the atmospheric radiation dose in various heights was measured on October 10. You can find the data released by TEPCO here. WDR 5 reported on the topic a week later. The full radio program (in German) is available here, the relevant part starts at 12:54.

Here’s a quote from the end of the segment on Fukushima (original German, translation below):

“Die Strahlung von bis zu 11 Sievert pro Stunde tötet einen Menschen in 40 Minuten. Der Höchstwert wurde in knapp 9 Metern Höhe gemessen, daß widerspricht der bisherigen Vermutung, daß sich der geschmolzene Brennstoff am Behälterboden gesammelt hat. Auf erschreckende Weise zeigt die Inspektion, daß TEPCO den Zustand im Reaktorinneren bisher nicht verstanden hat.”

WDR 5 Politikum, Millisievert der Woche, 2012-10-17

Translation by me:

“The radiation of up to 11 Sievert per hour kills a human within 40 minutes. The maximum was measured in at almost 9 meters height [author’s note: above containment dry well bottom], contrary to the previous assumption that the melted fuel gathered at the bottom of the pressure vessel. This shows in an alarming way that TEPCO still doesn’t understand the conditions inside the reactor.”

Diagram of the side of Fukushima Daiichi Unit 1 containment vessel, showing the measurement points below X100B

Measurement points below X100B, picture from TEPCO presentation “Investigation Results of the Inside of Unit 1 PCV at Fukushima Daiichi Nuclear Power Station“, October 10, 2012

The first problem is that the most emphasized point isn’t news at all: TEPCO doesn’t really know what’s going on inside the reactors. That’s status quo since about one and a half year, and the new measurements are part of the efforts to change that. Still these non-news are said to be particularly alarming.

Secondly, the most important implication of the unexpected radiation distribution is not mentioned. To the right, you can see a diagram showing the measurement points inside the containment vessel. At the highest point, D9, the atmospheric dose rate was about 9.8 Sv/h. D3 near the water level had about half that at 4.7 Sv/h, and D2 at the approximate water surface 0.5 Sv/h. The main source of radiation inside the reactor is, obviously, the fuel and especially the fission products contained in it. Despite the previous assumption that most of the molten fuel moved to the bottom of the reactor vessel if not into the containment, the radiation level actually is lower in the lower parts of the containment. This indicates that most of the fuel is still further up in the reactor, the meltdown was not as complete as feared, and the fuel did not melt through the bottom head of the reactor vessel.

At this point, that conclusion isn’t certain either, but I think it would have deserved some attention, especially compared to “we don’t know what exactly is going on inside the reactors”. It makes me sad to see how kind of bad non-news are emphasized beyond proportion while potentially good news are ignored.

(I’ve ignored other inaccuracies in the radio report to focus on the important points.)

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