Current Status and Challenges at Fukushima Daiichi Decontamination and Decommissioning

Transcription

1 2017 IAEA General Conference, Side Events Current Status and Challenges at Fukushima Daiichi Decontamination and International Centre, Vienna September 18, 2017 Naohiro MASUDA Chief Decommissioning Officer, President of Fukushima Daiichi Decontamination and Decommissioning Engineering Company, Tokyo Electric Power Company Holdings, Inc.

2 Map of Japan and location of Fukushima Daiichi NPS (1F) Fukushima Daini NPS Fukushima Daiichi (1F) 福島県 Fukushima Daiichi Nuclear Power Station １Ｆ 10km Fukushima From Daiini (2F) Tokyo From Tokyo 210km Fukushima 220km J-Village Daini Nuclear Power Station ２Ｆ J Village 1

3 Today s Topics 1. Current Status of Fukushima Daiichi NPS 2. Improving Work Environment 3. Fuel Removal from the Spent Fuel Pools 4. Toward Fuel Debris Removal 5. Information Sharing and Communication 2

4 3 Question Do you know the current status of Fukushima Daiichi?

5 Can you guess what these pictures are? 44

6 These pictures are top 15 images when searching Fukushima Nuclear Accident on Google 5

7 However, only 4 pictures show real 1F 6

8 Most of the pictures show other places Oil tanks on Tokyo Bay located in Chiba Pref. Other places hit by the disaster 7

9 1. Current Status of Fukushima Daiichi NPS THE FUKUSHIMA FORUM IV MARCH 15-18, 2016 TOKYO, JAPAN 8

10 安全第一福島第一 安全第一 福島第一 福島第一安全第一福島第一安全第一安全第一 (1) State of Units 1~4 All reactors are in cold shutdown condition. Plant parameters including RPV and PCV temperatures are monitored continuously 24 hours/day. Reactor building PCV PPV Fuel debris 392 assemblies Spent fuel pool 615 assemblies 566 assemblies Blowout panel (closed) Iron Frame for Building cover FHM girder Shielding Fuel removal cover Fuel removal completed クローラクレーン 1535 /1535 (Dec. 22, 2014) Unit 1 Cooling water injection Values as of 11:00 am on August 30, 2017 Temperature Temperature at the inside the Fuel pool bottom of containment temperature the pressure vessel vessel Unit Unit Unit Unit 2 Reactor coolant volume 3. 0 m3 /hour 3.0 m3 /hour 3. 0 m3 /hour Unit Unit 3 Unit 4 9

11 Compared to the situation just after the accident, the current level of radioactivity has been lowered to parts per hundred thousand, to per million. The concentrations outside the port are substantially below regulation limits. Concentration levels decreased further after closure of the sea-side impermeable wall. Regulation Limit Cesium 137: 90Bq/L Cesium 134: 60Bq/L Bq/l (2) Monitoring Level in the Sea North of Units 5&6 Discharge Outlet Completion of Sea-side Impermeable Wall Closure(Oct 26,2015) Bq/l Front of Shallow Draft Quay Completion of Sea-side Impermeable Wall Closure(Oct 26,2015) In Front of Unit 1-4 water-intake Sea-Side Impermeable Wall Near South Discharge Outlet 10

12 2. Improving Work Environment 11

13 Decreasing radiation dose (1) Decreasing Site Radiation Dose As a result of radiation reduction measure, workers don t have to wear full-face respirator or half-face respirator anymore in most parts of the site. : Area confirmed below 5μSv/h FY % FY % As of Dec % As of Mar % FY2015 Target Achieved Personal equipment in each zone as of Sep Percentage of workers in each zone Nonresponse Red Zone, [ 値 ] [ 値 ] General Uniform 9.2% Area where people can work in general uniforms (dust mask) 95% of the site Area where people should work in protective gears (full-face respirator or half-face respirator) Yellow Zone [ 値 ] Green Zone [ 値 ] (results from questionnaire in FY2016) 12

14 (2) Worker Security and New facilities Currently less than 6,000 persons/day are working on weekdays, which is twice as many as several years ago. Facilities such as Contractors Office Building and Large Rest House have created the environment where TEPCO and contractors can address the decommissioning work closely in the vicinity of the site. Changes in number of workers New Facilities Number of workers (TEPCO employees and contractors) per weekday engaged in work is 5,460 as of Jul Percentage of workers from local area is approx. 55% as of Jul Large rest house with a capacity of approx. 1,200 workers (since May 2015) Convenience store and shower rooms began operating (Mar. 2016) Fukushima Revitalization Meal Service Center was established in Ohkuma Town ( March 2015) Providing warm meals to Fukushima Daiichi Creation of employment opportunities in Ohkuma Town Ensuring stable long-term employment Large Rest House Change in the average number of workers (actual value) per weekday in the months following Trend of monthly exposure dose rate msv It is important to create an environment where contractors workers can work free from anxiety so that they can continue to work over a long period of time. Currently, approximately 90% of orders are fulfilled by negotiated contracts, which enables contractors to secure workers in a long term. By securing long term workers, more deliberate personnel assignment and human resource development is possible. Decommissioning through close ties with contractors Contractors Office Building began operating, which has enabled TEPCO and contractors work closely in the vicinity of the decommissioning site. On January 19, TEPCO and contractors jointly held a congress to pledge for no human-caused accident to happen. TEPCO s Office building Congress held by TEPCO and contractors Contractors office building Contractors logos 13

15 3. Fuel Removal from the Spent Fuel Pools 14

16 (1) Fuel Removal from the Spent Fuel Pool (Unit 4) Fuel removal started on November 18, Removal of 1535 fuel bundles completed on December 22, 2014 as scheduled This gives confidence to proceed to fuel removal at units 1, 2 and 3 No risk from fuel remains at unit 4. September 22, 2011 July 5, 2012 November 12, 2013: Completion of fuel removal facility (The volume of steel used is equivalent to those of Tokyo Tower) Fuel removal was completed on Dec. 22, Process of removing fuel rods at SFP Unit 4 Major risk reduction at Fukushima Daiichi 15

17 Removal of large pieces of rubble from the refueling floor and spent fuel pool was completed in Decontamination work was completed in June 2016 and shielding was completed in December In July 2017, installation of a dome roof started. The fuel removal will take place in the middle of FY2018. Immediately after the earthquake quake (2) Fuel Removal from the Spent Fuel Pool (Unit 3) After removal of large pieces of rubble Installation of a basis Installation of a dome roof Sep Major Tasks in the Future Feb May Sep Shielding (complete) 2Installing Cover & Fuel Handling Machine 3Undertaking Fuel Removal (Middle of FY2018) Installation of a dome roof started in July 2017 Dome roof (Installation drill at Onahama) 16

18 4. Toward Fuel Debris Removal 17

19 (1) Assumed Distribution of Fuel Debris It is assumed that at Unit 1, almost all fuel debris has dropped to the bottom of PCV. It is assumed that at Unit 2, most of fuel debris has remained at the bottom of RPV, while only a small amount has dropped to the bottom of PCV. It is assumed at Unit 3, a larger amount of debris has dropped to the bottom of PCV, while a small amount has remained at the bottom of RPV 構台 3 号機 Unit 1 Unit 2 Unit 1 Unit 2 Unit 3 Primary Containment Vessel (PCV) Water injection Reactor Pressure Vessel (RPV) At the time of investigation, deposits was found on the floor. Mar IRID At the time of investigation, a rise of steam was found Feb IRID Jul IRID 18

20 (2) Investigation inside the Primary Containment Vessel (Unit 3) 1 Outline of Investigation Unit 3 has a considerable amount of water inside its PCV. Therefore, underwater ROV (Remotely Operated Vehicle) was used to investigate inside the pedestal. X-53 penetrationhole for investigation X-6 penetration-hole CRD Replacement Rail Underwater ROV Pedestal Platform Slot Platform Basement Floor 19

21 (3) Investigation inside the Primary Containment Vessel (Unit 3) 2Obtained Image Several fallen obstacles and deposits, such as supposed solidified molten materials and grating were identified inside the pedestal. Image data collected in the investigation will be analyzed to identify the detailed situation inside the pedestal. X-53 penetrationhole for investigation CRD housing supporting X-6 penetration-hole Bottom of the CRD housing CRD Replacement Rail Pedestal Platform Slot Platform Basement Floor CRD ハウジング Bottom of the CRD housing Grating <Ref. > CRD housing and CRD housing support at Unit 5 CRD housing supporting Bottom of the CRD housing Inside the pedestal Inside the pedestal 20

22 5. Information Sharing and Communication

23 Explanation at public meeting Status Updates with regards to decommissioning are given to the public at the regular public meetings hosted by Fukushima Prefecture Opinions to TEPCO have been reflected to decommissioning measures (1) Two-way Communications with Local Residents Left:Ishizaki, Former Representative of the Fukushima Revitalization Headquarters Right:Masuda, Chief Decommissioning Officer, President of Fukushima Daiichi Decontamination and Decommissioning Engineering Company FY2016 Invitation to Site Visits Inviting the prefectural government and organizations Percentage of visitors from within the prefecture has increased to 31% (from 28% in FY2015) TEPCO aims to increase the number of site visitors to 20,000/y by Tokyo Olympics. Examples of comments received: Decommissioning is a big undertaking done with the cutting edge technology Seeing is believing Every time I visited Fukushima Daiichi, I was able to find some progress Number of visitors: 9,183 Overseas From within Fukushima prefecture 9% 59% Outside of Fukushima Prefecture 31% More than 28,000 visitors since the accident Briefings Briefings are held on the issue of great concern to residents Explanation on : The current state of dismantling Unit 1 building cover Overview of the training yard facility in Hirono Town Briefing held in Hirono Town (December 2015) Participants: 29 22

24 (2) Improvement of Information Sharing through New Contents The latest information including live footage, weekly work schedule and real time data are shared through website. TEPCO released new videos where Risk Communicators respond to the interests of people. In a new magazine, TEPCO focuses on understandability and familiarity by featuring persons in local or educational communities who are engaged in the decommissioning work. Information sharing through website Information Magazine <Live footage (Unit 1 side)> <Weekly work schedule> (Dismantling a cover at Unit 1) <An explanatory video by Risk Communicators > <Real time data on radioactivity > 1F Hairo Michi (first published in Apr. 2017) 23

25 (3) Open Innovation Platform TEPCO CUUSOO In a pursuit to decommission Fukushima Daiichi, TEPCO is seeking knowledge and expertise from across the world. We will welcome your suggestions at TEPCO CUUSOO Examples of complicated issues and operations HR: Human resources development and securing Sub criticality evaluation during fuel debris removal Consideration of effective removal from Unit 1 Reactor Building Upper Part Effective treatment of Iodine and Ruthenium in contaminated water Current status of the TEPCO CUUSOO Posted offers from visitors (as of end of Aug. 2017): Total: 44 (from Oversea: 22, from Japan: 22) Meetings: 10 Adopted: 1, adopted through direct contact; (Unit 1,2 Stack dismantling optioneering) To find more, please visit the website 24

26 25 In Conclusion Proceed with decommissioning work steadily in a stable manner for Fukushima Revitalization Share information learned with global nuclear industry in the hope of contributing to safety operation of nuclear fleet in the world

27 Thank you for your kind attention 26

28 Appendix

29 Spent fuel pool Conceptional Diagram of Reactor Cooling and generation of contaminated water Reactor bldg. PCV RPV Inflow of ground water Approx. 140m 3 /day (Provisional value, as of Aug.) Ground water Turbine bldg. Contaminated water Drawn from well-points etc. (provisional value as of Aug. 30m 3 /day) Cesium absorption apparatus Reactor cooling water Approx. 210m 3 /day Pump Cooling by recirculating cooling water KURION SARRY Added strontium removal function Treated water from multinuclide removal equipment Stored volume 802,947 m 3 (as of 24th Aug.) Cooling water tank Strontium-removed water Stored volume 194,412 m 3 (as of 24th Aug.) Desalination Approx. 170m 3 /day Approx. 380m 3 /day Storage tanks Remove 62 radioactive substances except for tritium Storage tanks Reduced Strontumconcentration Multi-nuclide removal equipment (ALPS) 28

30 Three principles for Measures to Counter Contaminated Water Three Principles 1Removing source of contamination 2Isolating fresh water from contaminated areas 3Preventing leakage of contaminated water 1Purification with multi nuclide removal equipment (ALPS) 3Augmentation of tanks Water treatment facility for Subdrain & Groundwater drain 2Paving to prevent rain water seepage into soil 2Pump up of groundwater through grondwater bypass wells 2Pump up of groundwater through subdrain 2Ice Wall (Frozen soil wall) 1Removal of contaminated water from trenches 3Ground improvement with liquid glass 3Sea-side Impermeable Wall 29

31 Landside Impermeable Wall (Frozen Soil Wall) The aim is to block the inflow of underground water and control underground water level. Freezing plant: 261kW/unit (30 units) Length:approx. 1,500m Planned volume of frozen soil : approx. 70,000 m 3 <Timeline> Jun Full-scale construction started Feb Work related to freezing facilities was completed Landside impermeable wall Mar Freezing started Aug Freezing of the last unfrozen part started Groundwater Control of groundwater flow Pipes for freezing liquid The status of freezing 30

32 Estimation of the Reactor conditions D/W water level S/C water level Unit 1 few few most part 2m Almost Full Unit 2 small large small 0.3m middle Unit 3 small 6m Full Snake Robot X-100 < PCV > RPV lower plenum > RPV core some some Scorpion Robot Sunfish Robot camera X-53 X-6 CRD rail Unit 1 Unit 2 Unit 3

33 Fukushima Daiichi NPS Map 提供 : 日本スペースイメージング,(C)DigitalGlobe 32