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Top > Releases ・ Announcements > Fukushima Daiichi NPS Prompt Report > 2013 > Steam-like Gas Found Near the Central Part of the Fifth Floor (Equipment Storage Pool Side) of Unit 3 Reactor Building at Fukushima Daiichi Nuclear Power Station (Follow-up Information 4)

Fukushima Daiichi NPS Prompt Report 2013

Fukushima Daiichi NPS Prompt Report (Jul 18, 2013)Steam-like Gas Found Near the Central Part of the Fifth Floor (Equipment Storage Pool Side) of Unit 3 Reactor Building at Fukushima Daiichi Nuclear Power Station (Follow-up Information 4)

This is a follow-up report on the statuses of steam-like gas found wafting through the air near the central part of the fifth floor(equipment storage pool side) of Unit 3.

Please refer to the following dust analysis result, sampled near the steam-like gas wafting place.

[Dust analysis result at the top of the Unit 3]

    Iodine 134: below the detection limit

    Cesium 134: 4.0×10^-5 Bq/cm3

    Cesium 137: 7.1×10^-5 Bq/cm3

For a half year, Cesium 137 has varied between 1.0×10^-3 Bq/cm3 and 1.0×10^-5, Cesium 134 has varied between 5.0×10^-4 Bq/cm3 and 1.0×10^-5Bq/cm3. The results today were between these ranges and there were data over the detection limits*.

* Detection limits

   Iodine 131 volatile:7.0×10^-6 Bq/cm3, granulous:4.2×10^-6 Bq/cm3  

   Cesium 134 volatile:1.5×10^-5 Bq/cm3, granulous:8.2×10^-6 Bq/cm3 

   Cesium 137 volatile:2.1×10^-5 Bq/cm3, granulous:1.1×10^-5 Bq/cm3 

Given the result and the status of the plant, we assume that the steam was generated as a result of that rain has leaked through gaps near the cover and has heated at the head of the primary containment vessel.

We will continue to monitor the status closely.
 


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