Current Situation of Fukushima- Daiichi Nuclear Power Plants and Difficulties in the Defueling Plan

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1 Current Situation of Fukushima- Daiichi Nuclear Power Plants and Difficulties in the Defueling Plan International Experts' Workshop on the Decommissioning of TEPCO's Fukushima Daiichi Nuclear Power Plant Unit 1-4 March 14, 2012 Tokyo, Japan Shunichi Suzuki, ph.d R&D Center Tokyo Electric Power Company

2 2012 The Tokyo Electric Power Company, INC. All Rights Reserved. Overview Image of BWR-4 Reactor Building (R/B) Pressure Vessel (RPV) Containment Vessel () Steam Turbine Building (T/B) Steam Turbine Suppression Chamber Feed Water Steam Condenser Cooling Water

3 Work Steps Involved in Fuel Debris Removal(1/3) Phase 1 Phase 2 Phase 3 FY Within two years (Early) (Mid) (Late) 2 Ensure Access Route via Decontamination Leakage Point Inspections Inspection from Outside of Internal Inspection and Sampling Internal RPV Inspection and Sampling Target Determining methods for repairing lower parts of Determining water stop methods Reactor Building Decontamination 3 Stopping Inter-building Water Leakage Lower Parts Repair 4 5 (Decontaminate each area corresponding to each work requiring) Completion of flooding of lower parts of Determinig internal investigation methods HP HP HP Determining methods to HP Filling the Lower Part with Water 6 repair upper parts of Upper Parts Repair 7 8 Open RPV Filling /RPV with Water Completion of flooding of upper parts of Determining RPV internal investigation methods Within 10 years HP Determining fuel debris removal methods and completion of preparation of fuel debris containers, etc. 9 Determining processing / disposal methods of fuel debris After years Fuel Debris Removal HP Steps 1 Reactor Building Decontamination (Decontaminate each area corresponding to each work following 2 sequentially) 2 Leakage Point Inspections Inspection from Outside of 3 Stopping Inter-building Water Leakage Lower Parts Repair After achieving stopping inter-building water leakage, switch intake sources for circulating water cooling from accumulated water in turbine buildings to torus. Images Spent Fuel Pool Fuel debris Decontamination Devices (remote control) RPV From water treatment facilities Decontamination Devices Turbine Building Camera-mounted Observation Devices (remote control) Spent Fuel Pool Penetrations RPV Penetrations Camera-mounted Observation Devices Turbine Building Repair Devices (remote control) Spent Fuel Pool RPV Repair Devices Torus Leakage To water treatment facilities Torus Leakage Torus Stop Leakage Contents In order to easily access s, decontaminate work area via high-pressure washing, coating, and scraping, etc. Inspect leakage points in the and reactor building via manual or remote dose measurement, and camera, etc. Estimate and inspect the status of inside via measurement of gamma ray from outside of, and acoustic inspection, etc. Repair leakage points and then stop water leakage because it is believed that removing debris while underwater due to the excellent radiation shielding afforded will be the reliable method. First, repair points at lower parts of for internal inspection. Points to Note on Development The existence of areas of high dosage (several hundred to 1,000 msv/h). Access restriction due to rubble scattered about inside R/B. Remote decontamination methods corresponding to the above need to be considered and established. Inspection areas may be located in highly radioactive environments, under contaminated water, and in narrow parts. Develop leakage point inspection methods and devices. Develop methods and devices for internal inspection from outside of. While continuing water injection for circulating water cooling, stop water leakage under highly radioactive and water running conditions. Develop technologies and methods to repair leakage points and stop water leakage. Consider and develop alternatives The Tokyo Electric Power Company, INC. All Rights Reserved. 3

4 Work Steps Involved in Fuel Debris Removal(2/3) Phase 1 Phase 2 Phase 3 FY Within two years (Early) (Mid) (Late) 2 Ensure Access Route via Decontamination Target Internal Building 1 Decontamination Determining methods for repairing lower parts of Determining water stop methods Leakage Point Inspections Inspection from Outside of Internal Inspection and Sampling Internal RPV Inspection and Sampling 3 Stopping Inter-building Water Leakage Lower Parts Repair 4 5 (Decontaminate each area corresponding to each work requiring) Completion of flooding of lower parts of Determinig internal investigation methods HP HP HP Determining methods to HP Filling the Lower Part with Water Upper Parts Repair Filling /RPV with Water Steps 4 Filling the Lower Part with Water 5 Internal Inspection and Sampling 6 Upper Parts Repair 6 repair upper parts of 7 8 Completion of flooding of upper parts of Determining RPV internal investigation methods Open RPV Within 10 years HP Determining fuel debris removal methods and completion of preparation of fuel debris containers, etc. 9 Determining processing / disposal methods of fuel debris After years Fuel Debris Removal HP After achieving construction of boundaries at the lower parts of, switch intake sources for circulating water cooling from torus to. Images Spent Fuel Pool Torus RPV Water-filling From water treatment facilities Turbine Building To water treatment facilities Spent Fuel Pool Camera Sampling Torus RPV Expansive pipe Observation Devices Turbine Building Spent Fuel Pool Repair Devices (remote control) Torus RPV Penetrations Repair Devices Contents Partially fill the lower parts of with water before starting internal inspection. Ascertain distributions of fuel debris flowed from RPV by internal inspections and samplings etc. In order to fill the full with water, repair leakage points at the upper parts of by manual or remote methods. Points to Note on Development Same as 3 Place top priority on the construction of boundaries at the lower parts of (including filling torus with grout materials). Access restriction due to high radioactive conditions and unknowing internal conditions (thickness of internal water, existence of debris, etc.) Develop remote inspection methods and sampling methods corresponding to the above. Same as 2 Develop technologies and methods to repair leakage points and stop water leakage (same as 3) The Tokyo Electric Power Company, INC. All Rights Reserved. 4

5 Work Steps Involved in Fuel Debris Removal(3/3) Phase 1 Phase 2 Phase 3 FY Within two years (Early) (Mid) (Late) 2 Ensure Access Route via Decontamination Target Internal Building 1 Decontamination Determining methods for repairing lower parts of Determining water stop methods Leakage Point Inspections Inspection from Outside of Internal Inspection and Sampling Internal RPV Inspection and Sampling 3 Stopping Inter-building Water Leakage Lower Parts Repair 4 5 (Decontaminate each area corresponding to each work requiring) Completion of flooding of lower parts of Determinig internal investigation methods HP HP HP Determining methods to HP Filling the Lower Part with Water 6 repair upper parts of Upper Parts Repair 7 8 Open RPV Filling /RPV with Water Completion of flooding of upper parts of Determining RPV internal investigation methods Within 10 years HP Determining fuel debris removal methods and completion of preparation of fuel debris containers, etc. 9 Determining processing / disposal methods of fuel debris After years Fuel Debris Removal HP Steps 7 Filling and RPV with Water Open the upper cover on RPV Overhead Crane Container 8 Internal RPV Inspection and Sampling 9 Fuel Debris Removal RPV Upper Cover Truck Expansive Pipe Fuel Debris Container Images Spent Fuel Pool RPV From water treatment facilities To water treatment facilities Spent Fuel Pool Debris Container Camera, Cutting, Drilling, Gripping, and Suction Devices Removal Torus Torus Torus Contents After filling /RPV with water enough to ensure shielding, open the upper cover on RPV. Ascertain conditions of fuel debris and internal RPV structures by internal RPV inspections and samplings etc. Remove debris inside RPV and Points to Note on Development (Place top priority on the construction of boundaries as per 6) Restricted access route due to high radioactive conditions and unknown internal RPV conditions (thickness of internal water, existence of debris, etc.) Develop remote inspection methods and sampling methods based on the above. Expand technology development scope depending on distribution status of fuel debris (No experience of fuel removal of inside at TMI) Develop more sophisticated technologies and methods than those of TMI 2012 The Tokyo Electric Power Company, INC. All Rights Reserved. 5

R&D Projects for Fuel Debris Removal Remote Decontamination Technology Purpose Reduce the radiation dose for following surveys and repair works Challenging Points Optimal decontamination way for each

Leakage Detecting Technology Purpose Detect the leaking points w/o high exposure Challenging Points High radiation, little space Remote checking/control system Example (Expected leaking points) Torus

instruments with remote control system under high temp.

6 R&D Projects for Fuel Debris Removal Remote Decontamination Technology Purpose Reduce the radiation dose for following surveys and repair works Challenging Points Optimal decontamination way for each situation Remote control tech. for high radiation or restricted work space Existing Techniques Water Jet Flushing Surface Grinding Spent Fuel Pool Debris RPV DS Pit Turbine Bldg. Leakage Detecting Technology Purpose Detect the leaking points w/o high exposure Challenging Points High radiation, little space Remote checking/control system Example (Expected leaking points) Torus Space Repair Leakage Self-propelled Brushing Strippable Paint Inner Survey Technology Purpose Survey the condition of and RPV, and the location and property of debris Challenging Points Measuring instruments with remote control system under high temp., high humidity, and high radiation Splash prevention system Example Leakage Mending Technology Purpose Develop the waterstops and leakage mending methods for various leakage points Example Iron 鋼製カバー cover (as Additional boundary) Sealing ring シートリング ( 耐久性素材 ) 押さえリング付 Spider-shaped スパイダー frame Challenging Points Availability in the contaminated water Remote procedure/control Air Lock シールパッキン Gasket Splash prevention system of radioactive materials Camera Mirror Machine Hatch Inside the Dry Well ターンバックル ( パッキン固定具 Turnbuckle ) 2012 The Tokyo Electric Power Company, INC. All Rights Reserved. ターンバックル ( パッキン固定具 Turnbuckle )

Recent View of Fukushima Daiichi (Units 1 to 4) 2012 The Tokyo Electric Power

Dose Rate Map of Fukushima Daiichi Site (As of 5:00PM Jan.

Dose Rate Map of Inside of R/B (1st Floor of Unit 1) Monitored from Apr. to Nov. 2011 Aisles: ~10 msv/h MAX Stairs: ~100 msv/h Highest: ~3000mSv/hr Stairs MAX Shielding Wall since 8 th Sep.

11 Dose Rate Map of Inside of R/B (1st Floor of Unit 1) Monitored from Apr. to Nov Aisles: ~10 msv/h MAX Stairs: ~100 msv/h Highest: ~3000mSv/hr Stairs MAX Shielding Wall since 8 th Sep. MAX * Detail The data with * are monitored 2.2m over the floor level * * * * * * * * * * Funnel Floor Penetration MAX Unit : msv/hr 2012 The Tokyo Electric Power Company, INC. All Rights Reserved. 11

Dose Rate Map of Inside of R/B (2nd Floor of Unit 1) Monitored from Apr. to Nov.

13 Dose Rate Map of Inside of R/B (3rd Floor of Unit 1) Monitored from Apr. to Nov Rubbles Aisles: ~150 msv/hr Water on the Floor: ~650 msv/hr Puddle Under the Stairs Rubbles 2012 The Tokyo Electric Power Company, INC. All Rights Reserved. 13

2012 The Tokyo Electric Power Company 17, INC.

[Movie taken by Quince] Obstacles on the stairs

[Movie] Rubbles on 4 th Floor (Unit 1) Rubbles around

co.jp/en/news/library/movie-01e.html Jan.

19 2012 The Tokyo Electric Power Company, INC. All Rights Reserved. [Movie] Inside of Pressure Containment Vessel (Unit 2) Jan. 19, 2012 Unit: msv/h Primary objective (temperature measurement) was achieved successfully Water level was not confirmed within the reach of the fiber camera

20 [Movie] Normalcy of inside of a (BWR-5) Kashiwazaki-Kariwa, Unit 4 (BWR-5, 1100MW) inside is crowded with a lot of facilities and pipe-lines packed in. The floor is not flat but has many steps. Units 1-4 of Fukushima Daiichi are BWR-4 plants and the space is significantly smaller than this movie 2012 The Tokyo Electric Power Company, INC. All Rights Reserved. 20

21 Summary of Dose Rate Survey of Inside of R/B Dose rates in the reactor buildings is from tens to hundreds msv/hr in most areas. Thousands msv/hr areas are existing due to some radiation source. Dose rate survey maps are similar among Unit 1 to Unit 3, even though the reactor building of Unit 2 did not experience a hydrogen explosion. The pipes lying on the floor/aisles, so the floors has some steps originally. Rubbles are scattered on the floor, which prevents the robots from running through the floor. Rubbles are also scattered on the stairs The Tokyo Electric Power Company, INC. All Rights Reserved. 21

22 Technical Challenges for Defueling Decontamination of Reactor Buildings Various targets of decontamination; floor, wall, ceiling. Not only structural objects, but puddles and atmospherics should be decontaminated. Technologies for coating or shielding the radiation sources will also required. Inspection of Inner & Leaking Points Most inspection (photographing, dose measurement, acoustic diagnostics) will be done in the contaminated water or in little/crowded space. Various situation such as high temp, high humidity, under water. All measurement instruments must have high tolerability to radiation and long distance control system Repair Works for & Leaking Points Leakage mending methods under the highly contaminated water Water injection to a reactor cannot be stopped during the /leakage repair The Tokyo Electric Power Company, INC. All Rights Reserved. 22