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ONAGAWA NPS Dose Reduction

ONAGAWA NPS Dose Reduction. October 12, 2006 TOHOKU Electric Power Co.,Inc. Miyagi Prefecture. Location. Onagawa NPS. Specifications. Annual Average Dose. Average of BWRs in Japan. Unit2 Operation started. Unit3 Operation started. Unit 1 Operation started.

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ONAGAWA NPS Dose Reduction

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  1. ONAGAWA NPS Dose Reduction October 12, 2006 TOHOKU Electric Power Co.,Inc.

  2. Miyagi Prefecture Location Onagawa NPS

  3. Specifications

  4. Annual Average Dose Average of BWRs in Japan Unit2 Operation started Unit3 Operation started Unit 1 Operation started

  5. Annual Collective Dose Unit2 Operation started Unit3 Operation started Unit 1 Operation started

  6. Onagawa NPS Outage Dose Unit 1 Unit 2 Unit 3

  7. Our Dose Reduction Strategy • Measures on the design stage • Clean-Plant operations on the construction stage and the test run operation stage • Continuous Dose Reduction

  8. 1.Dose Reduction Measures on the design stage DoseReduction Reducing Radiation Improvement of Water Treatment Capability CRUDreduction CRUD Generation Control Use of Low-Co materials Improvement of Working environment Shielding Optimization Shortening exposure time Improvement of equipment Automation/Remote operation

  9. 2.Clean-Plant operations on the construction stage and the test run operation stage 　・　Keep Work area clean 　・　Use wrapping against construction dust 　・　Introduce Water chemistry technologies

  10. 3. Continuous Dose Reduction 3-1. Management of Workers’ Dose Data 3-2. Monitoring of Dust & Radiation 3-3. Water Chemistry Technologies 3-4. Dose Reduction at Outages

  11. 3-1.Management of Workers’ Dose Data Work Code Input Device Alarm Personnel Dosimeter Work Code and Dose data Work Code Controlled area Work Code & Dose data

  12. 3-2.Monitoring of Dust & Radiation

  13. 3-3．Water chemistry Dose rate of PLR piping of our plants are remarkably low compared to other plants.

  14. 3-4. Dose Reduction at Outages • Education program for foremen during Outage • Holding “HP work Schedule meetings” periodically • HP Patrol during Outage frequently • Posting up the Detailed Radiation Map of D/W area

  15. Special issue in 2005 We performed special activities for 1.Unit 3 Fuel Leakage …Our first experience 2.Earth Quake on Aug.16,2005

  16. 1． Unit 3 Fuel Leakage On Jul.2,2005 We first experienced fuel leakage at Unit 3 resulted in the increasing value of OG monitor . Main measures we took were as follows : Surveillance of OG Prevention from intake of I-131

  17. 2．Earth Quake (Aug.16,2005) All Units in Operation were shut down automatically . SCRAM triggers are set to 200 GAL: horizontal earthquake movement, 100 GAL : vertical . Seismic Center Magnitude : 7.2 Depth : 42Km approx.

  18. 2-1.Influence to electricity in 2005 Unit 1 Earth QuakeAug.16 MWe #17 MWe Unit 2 Earth QuakeAug.16 #7 MWe Earth QuakeAug.16 Unit 3 #3

  19. 2-2.Comparison of Outage Dose of Unit 3 before / after the Earth Quake Before After Jun.10/2004 ~Oct.5/2004 Sep.27/2005 ~Apr.18/2006

  20. Recent Annual Average Dose Unit3 Operation started Average of BWRs in Japan

  21. We keep going to make efforts for ALARA!

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