OCCUPATIONAL EXPOSURE at JAPANESE NUCLEAR POWER PLANTS in 2006  2007 ISOE Asian ALARA Symposium OCCUPATIONAL EXPOSURE at JAPANESE NUCLEAR POWER PLANTS in 2006 September 12-14, 2007, Seoul, Korea Yoshihisa Hayashida Safety Information Division Japan Nuclear Energy Safety Organization (JNES)

Nuclear Power Plants in Japan as of March 31, 2007 BWR PWR Total In Operation No. of Units 32 23 55 Output (MWe) 30,101 19,366 49,467 Under Construction 1 2 1,373 912 2,285 On Planning 9 11 11,869 3,076 14,945

Nuclear Power Plants in Japan 女川 福島第一 ふげん (2003 年より廃止措置準備中 ) (FBR)) ( 敦賀 志賀 出力規模 50 万 kW 未満 100 以上 合計 53 基 出力 47,122MWe 7 8 TEPCO 2 1 5 Oma Tomari Higashi Dori Onagawa Tokai No. 2 Hamaoka Ikata Sendai Genkai Shimane Kaminoseki Takahama Oi Mihama Tsuruga Tokai Fugen (on a decommissioning stage since 2003) Monju Shika Fukushima Daiichi Fukushima Daini (On the decommissioning stage since 1998) Namie-Odaka Kashiwazaki-kariwa ３ Output scale In operation Under Construction On planning stage Less than 1,000,000kW Total 55 Units 49,467MWe (PWR 23 units, BWR 32 units ) 500,000kW More than 55 Units in Operation (PWR 23, BWR 32) as of March 31, 2006

Trend of Capacity Factor in Japanese plants

Individual Dose in Fiscal Year 2006 (April 2006 – March 2007) Plants Units Persons mSv /person BWR 32 44,129 1.0 PWR 23 22,718 1.1 GCR 1 1,293 0.02 Total 56 66,895

Trend of Individual Average Dose in Japanese plants

Collective Dose in Fiscal Year 2006 (April 2006 – March 2007) Plants Units Person-Sv /unit BWR 32 42.43 1.33 PWR 23 24.97 1.09 GCR 1 0.03 Total 56 67.43 1.23 (LWR)

Trend of BWR Average Collective Dose per Reactor in Japanese Plants

Trend of PWR Average Collective Dose per Reactor in Japanese Plants

Trend of Maintenance Exposure at Japanese BWRs

Trend of Maintenance Exposure at Japanese PWRs

Collective Dose During Outage vs Collective Dose During Outage vs. Year of Commercial Operation Started (BWR: 1996 - 2006)

Collective Dose During Outage vs Collective Dose During Outage vs. Year of Commercial Operation Started (PWR: 1996 - 2006)

BWR Average Collective Dose per Reactor by Country

PWR Average Collective Dose per Reactor by Country

BWR Three Year Rolling Average by Plant in USA and Japan

PWR Three Year Rolling Average by Plant in USA and Japan

Dose Rate at PLR Piping in Japanese BWR and US BWR

Operation Period and Maintenance Period by Country from 1996 to 2005

Further Exposure reduction Japanese utilities are continuing the approach for further exposure reduction. Regulatory side will encourages and support their activity. The effort of the improvement on inspection way for nuclear facilities is continued in Japan.

Summary BWR average collective dose per reactor for 2006 decreased 3 years in a row, and the value of 1.33 person-Sv is the lowest in the past. Average collective dose per reactor for PWRs shows a stable trend in general in around 1 person-Sv. Relatively much maintenance work is performed in Japanese plants. It is expected that the improvement of inspection way and utility’s ALARA activity will promote to decrease the exposure in Japanese plants.

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