Development of human resources

Transcription

1 Current Status of Decommissioning of Advanced Thermal Reactor Fugen and Prototype Fast Breeder Reactor Monju, Development of human resources November 22, 2018 Japan Atomic Energy Agency Contents 1 Decommissioning of Fugen Decommissioning of Monju Development of human resources

2 2 Decommissioning of Fugen Outline of Fugen 3 Fugen; Prototype reactor (Heavy water-moderated boiling light water cooled) First criticality in 1978, and continued operation until 2003 Decommissioning plan approval in Feb Core : Pressure Tube Type Moderator : Heavy Water Coolant Output : Boiling Light Water -Pressure : 68 kg/cm 2 -Temperature : 284 : 165 MWe (557MWt) Containment Vessel First criticality: March 1978 Commercial operation : March, 1979 Final shutdown : March, MOX fuels were utilized Capacity factor: 62% Decommissioning planning start: 1998 Decommissioning plan approval : Feb Calandria Tank Steam Drum Steam Heavy Water (Moderator) Control Rod Light Water (Coolant) Turbine Generator Transformer Condenser Fuel (UO 2 & PuO 2 :MOX) Sea Water (224 channel) Pump Pressure Tube Recirculation Pump Feed Water Pump (2 Cooling loops)

3 Basic Schedule of Fugen Decommissioning 4 Fugen s decommissioning program consists of four phase The program will be completed in 2034(JFY2033) Reactor core dismantling will be started several years later Preparation 2008 Heavy water system etc. Detritiation Here! Periphery Facilities Dismantling Reactor Dismantling Building Demolition 2034 Termination of Operation (March 29, 2003) Discharge of Fuel (-Aug.,2003) Decontamination of Reactor Cooling System (Nov.-Dec., 2003) Transfer of Spent Fuel Withdrawal/Transfer of Heavy Water The transfer of heavy water was completed in April 2014 Core cooling System, Control and Measurement Instrument System etc. Approval of the Decommissioning Plan Feb.12, 2008 Reorganization of FUGEN Fugen N.P.S. >> FUGEN Decommissioning Engineering Center Fuel Handling/storage facilities, Heavy water system etc. Reactor core Ventilation system Release of controlled area Building Status of Dismantling(Fugen) 5 Removal of condensers, heaters and piping of under the turbine system is completed Dismantlement of Turbine System Main steam Pipe No.5 Feed water heater Feb (When Approval of the Decommissioning Plan) March 2018

4 Outline of Fugen Decommissioning 6 Heavy water withdrawal is completed Current status is phase2:peripheral Dismantling of Reactor and Dismantling of equipment that are no longer used Reactor dismantling is under development 1Heavy Water System etc. Detritiation Sampling from Recirculation System Dismantling of Turbine and Condenser 2Periphery Facilities Dismantling Peripheral Dismantling of Reactor Dismantling of equipment that are no longer used 3Reactor Dismantling Dismantling after Reactor Dismantling Waste Treatment Facilities Ventilation System etc. Heavy Water Withdrawal Residual Heavy Water collection Removal of Tritium Reactor Dismantling Current phase(since May 2018) 4Building Demolition Building Demolition Example of Cutting Technologies(Fugen) 7 General cutting technologies ; band saw, gas cutting, orbital pipe cutting, gasoline oxygen Checking its ability and efficiency for accumulation of the valuable data Cutting by a band saw Cutting by a plasma cutting machine Gas cutting equipment (manual) Orbital pipe cutting machine Automatic gas cutting machine (selfpropelled) Gasoline oxygen cutting (manual)

5 Development of Fugen Reactor Dismantlement 8 Ensuring the safety Decreasing the exposure dose due to the activated dust + Preventing the firing of Zirconium material Shortening the work period Shortening the work period for dismantling the complicated core Dismantling under the water (conceptual scheme) Waste Container Under-water dismantling Appropriate cutting machine and procedure Holding Machine Cutting Machine Secondary cutting Machine Test on cutting method under the water Study on applicability and release behavior of dust Temporary pool Theme of dismantlement of Fugen reactor core 9 Remote & under water Cutting technology of double tube from inside Temporary pool Cutting in narrow space Pressure & Calandria tube Zirconium Alloy (<4.3mm) Radiation rate in the reactor Ca. 30~200Sv/h Activity (Bq/ton,γ) Upper iron water >10E+13 Shield : Steel (150mm) >10E+12 Calandria tank Upper tube plate Stainless Steel(150mm) Thick plate cutting under water >10E+10 >10E+05 (8 yrs. After shutdown) 9

6 Development for Fugen Reactor core Dismantlement 10 Theme of material Radioactivity level is high (Activated materials) Pressure Tube is zirconium alloy Reduction of exposure by active dust during cutting Prevention of zirconium alloy powders fire during cutting Theme of structure Double tube and narrow and complex structure requires a lot of cutting lines Simultaneous cutting method or the same performance cutting method for double tube Shortening the work period by remote underwater cutting Development of Underwater Cutting Head for pipe insertion Laser head AWJ head Development for taking samples from Fugen reactor core 11 Purpose of taking samples from reactor core Radioactive inventory have to be evaluated more accuracy for exposure reduction, work shortage, rational dismantling and waste packaging Cutting tool Sampling device for Fugen reactor was developed, which can take samples at high dose rate and complicated structure. 約 9m 約 4.5m Sampling device To make hole for access to core part Vibration Preventing 防振板 Board Core 炉心タンク Tank H29 Next 年度以降の計画 2018 Plan approach from lateral ( sampling 側部から炉心タンク from core 等の試料を採取 tank etc. ) Insert length: around.5.5m diagrammatical view from upper part turn and expansion and contraction mechanism Pressure 圧力管 tube Calandria カランドリア管 tube Control 制御棒案内管 rod guide tube sampling point : 試料採取予定箇所 Calandria カランドリアタンク Tank 2018 Plan H28 approach 年度計画 from bottom ( sampling 下部から圧力管等の試料を採取 from pressure tube etc. ) Sampling Device from Reactor core (spec) From bottom Maximum length:about 10m maximum diameter:about 110mm From lateral Maximum length:about 7m maximum diameter:about 140mm Sampling device from bottom

7 12 Dismantling work simulation system Dismantling work simulation system has been developed to support the formulation of the methods and procedures for dismantlement, considering radiation exposure reduction. The system enables to visualize the dose at the site and evaluate the exposure dose according to the work scenario of the workers. Build a work plan & Play the simulation image of the work plan Dose visualization (3 dimensions) Work scenario Radiation exposure level Example : Survey work around the reactor core part Supervisor : Dose rate / Distance Max dose rate (Outside) Total length of walking path Worker Max dose rate (Outside) : Dose rate / Distance Total length of walking path The system was developed in cooperation with Institute for Energy Technology in Halden, Norway Worker selection (equipment) Dismantling tool selection Technology development of decontamination (1) Research on dry decontamination method on inner surface of small bore piping In order to make an object in a piping form to be clearance product, it is necessary to cut piping vertically and open the inner surface for decontamination and measuring the radioactivity. Small bore piping has been excluded from the objects to be clearance products so far, since cutting vertically is omitted due to work efficiency issues. Aiming at making small bore piping to be clearance products, research on decontamination method by the piping cut horizontally into round slices with dry decontamination equipment using projection material (abrasive) has been carried out from FY2014. Test record FY 2014 Dry decontamination equipment Dust collector FY 2015,2016 FY 2017 Mock test using the objects with rust and plating on the inside was carried out and the result that those rust and plating can be removed was confirmed. Shift to hot test Hot test using actual wastes in Fugen Hot test -Change the shape of the projection material for the purpose of shortening decontamination time -Use actual waste to check if the inner surface of complex shape object can be decontaminated. Condition of inner surface after decontamination Control panel Decontamination machine Before decontamination Drum Small bore piping Discharge duct Projection material Impeller Internal cylinder Structure of dry decontamination equipment Changes in the amount of radioactivity on the inner surface of pipe 24 hours after decontamination Confirmed results By cutting the small bore piping into round slices, radioactive substances such as rust adhering to the inner surface can be easily removed, and the decontamination effect was confirmed that the radioactivity concentration became below the clearance level within 24 hours (maximum DF 200 or more). Decontamination on the inner surface of complex shape object is also possible. 13

8 Technology development of decontamination (2) 14 Research aimed at establishment of electrolytic polishing decontamination technology for equipment and piping before dismantling In Fugen, chemical decontamination for the systems was carried out at reactor shut down. Decontamination before dismantling is required to reduce the exposure dose of workers, technology development for decontamination has been carried out by collaborative research. In FY2016 : Element test for electrolytic polishing decontamination using sodium chloride solution as a decontamination liquid was carried out, and data on decontamination effect and operability etc. to be used for practical application were obtained. In FY2017 : Considering the application to facilities in service, the test was carried out using sodium nitrate, which is not containing chlorine, as a decontamination liquid, in addition to improving the measurement method before and after decontamination. As a result of the two-year test, relationship between polishing depth and decontamination efficiency was confirmed. This made it possible to decide device specifications and a operation method, and offer the prospect of the practical application. Electrolytic testing device Conceptual diagram for fluidized electrolytic method The test was carried out by a sponge type method in which the nozzle was wrapped with a sponge and brought into contact with the processing object. 15 Decommissioning of Monju

9 Principal Design and Performance Data of Monju 16 Electricity output: 280MWe (714MWt), sodium-cooled, MOX-fueled Outer shield Secondary sodium (Consists of independent A, B, C loops) Reactor containment vessel Primary sodium (Consists of independent A, B, C loops) Primary circulation pump Superheater Turbine Generator Control rod Secondary circulation pump Air cooler Evaporator Condenser To floodway Circulation pump Cooling water (Sea water) Core fuel Intermediate Heat Exchanger (IHX) Over flow tank Dump tank Feed water Primary cooling system Secondary cooling system Water/steam system Chronological Issues regarding Monju Project 17 Monju; Prototype Fast Breeder Reactor Japanese government decided Monju decommissioning in Dec Decommissioning plan approval in March 2018 May 2013: March 2011: March 2018: NRA approves Monju decommissioning plan. Dec. 2016: Japanese government decided the decommissioning of Monju. Monju received order from NRA to improve the plant management on safety measures. Nuclear Safety Guidelines were revised based on the lessons learned from Fukushima. Tsunami following the earthquake caused a serious nuclear accident at TEPCO s Fukushima Nuclear Power Station. Aug IVTM fall incident May 2010: Resumed Performance Tests Dec. 1995: Sodium leak accident April 1994: Initial criticality IVTM NRA: Nuclear Regulation Authority IVTM: In-vessel Transfer Machine

10 Main item Basic Schedule of Monju Decommissioning 18 Whole process of Monju decommissioning is classified into 4 stages The program will be completed in JFY2047 Dismantling plan after 2 nd stage is under consideration, decommissioning plan will be revised until starting the 2nd stage Here! Stage 1 st stage Period of fuel unloading 2 nd stage Period of preparation for decommissioning 3 rd stage Decommissioning period Ⅰ 4 th stage Decommissioning period Ⅱ Fiscal year 2018 ~ ~ 2047 Fuel unloading Preparation for dismantlement of sodium equipment Dismantlement of sodium equipment Survey and assessment of radioactivity Dismantlement of water/steam system facilities etc. Dismantlement of buildings Evacuation of radioactive solid waste Note: Regarding the plans for transfer of spent fuels and treatment/disposal of sodium, the government's conclusion for the plan will be reflected by the time fuel unloading completes. Outline of Monju Decommissioning 19 Current status is stage 1:Fuel unloading (typical feature of FBR) In this stage, removal of the Secondary System Sodium is also carried out Main target of dismantlement at stage 2 is Water/Steam, Turbine System, and stage 3 is sodium facilities 1Fuel unloading Survey and Assessment of Radioactivity 2Preparation for decommissioning Survey and Assessment of Radioactivity Fuel unloading Removal of the Secondary System Sodium Current phase(since March 2018) 3Decommissioning period Ⅰ 4Decommissioning period Ⅱ Main Target of Dismantlement Water/Steam, Turbine System Main Target of Dismantlement Water/Steam, Turbine System Sodium facilities Main Target of Dismantlement Buildings

11 Scheme of Monju Fuel Unloading 20 Fuel handling machine Ex-vessel fuel transfer machine Rotating plug Na Na Spent fuel pool Reactor vessel Ex-vessel storage tank (EVST) Spent fuel canning system Spent fuel cleaning system : fuel treatment and storage : fuel unloading Basic Schedule of Monju Fuel Unloading 21 Current Status; Fuel treatment and storage started this August (42 fuels have been carried out on 11 th Nov.) Next stage; Fuel unloading from Reactor vessel to EVST, and Fuel treatment and storage (from EVST to spent fuel pool) Repeat the above processes 3 times, and plan to reach the completion of fuel unloading works until the end of 2022 Fiscal year Fuel treatment and storage EVST Spent fuel pool (530 fuel assemblies) Here! Completion of fuel unloading Fuel unloading Reactor Vessel EVST (370 fuel assemblies) Inspection of equipment Restoration of fuel treatment facilities Inspection of rotating plug Secondary sodium draining Completion of secondary sodium draining

12 Considerations for Monju dismantling (1) 22 Dismantling of fast reactor of prototype reactor class is the first experience in Japan. The decommissioning plan (dismantling plan) after fuel unloading is currently under consideration *. Fast reactors use sodium as coolant, which is a technical issue not experienced in light water reactors. Considering with reference to experience of overseas fast reactors 1) Draining sodium 2) Dismantling method of sodium equipment (Stabilization treatment of residual sodium using inert gas (ex. carbon dioxide gas etc.), and washing,dismantling) Technical issues to consider especially for dismantling reactor vessels *The plans for transfer of treatment/disposal of sodium shall be considered in the 1st stage, and they will be reflected in the decommissioning plan by the time the 2nd stage begins. Consideration for Monju dismantling (2) 23 Example of draining sodium in Superphénix, France Sodium accumulated part Siphon pipe Sodium Draining sodium accumulated in the lower part of core (diagrid) using the principle of siphon Source:IAEA-TECDOC-1405 Operational and decommissioning experience with fast reactors M Piping bellows Laser head Robot Draining sodium by drilling a hole in the sodium accumulated part (core catcher) from the upper part of core using a mechanical drill Source:IAEA-TECDOC-1405 Operational and decommissioning experience with fast reactors Cross-section diagram of primary system at Superphénix Source : Recent Sodium Technology Development for the Decommissioning of the Rapsodie and Superphénix Reactors and the Management of Sodium Wastes, p , Nuclear Technology Vol.150 Apr Draining sodium by drilling a hole in the sodium accumulated part (piping bellows) with laser by a remote control robot Source:Control and maintenance of the Superphénix knowledge and its specific sodium skills through an innovative partnership between EDF and AREVA, PREDEC 2016, February 16-18, Lyon, France 23

13 24 Development of human resources Human resource development Secondment and short visit to overseas Staff from Fugen and Monju have been dispatched to overseas decommissioning plants for collecting and surveying the knowledge on decommissioning. France: Staff assignment arrangement on cooperative activities on decommissioning sodium cooled fast reactor was newly signed between CEA and JAEA on January, Secondment from "Monju" will be started within FY2018. UK : Co-operation arrangement between NDA and JAEA in the field of radioactive waste management and decommissioning including secondment was revised in September, 2018 in order to expand cooperation for decommissioning of Monju with UK. Record of secondment and short visit Dispatch period Dispatch area Outline of tasks Sep. 30 to Dec.18, 2009 Winfrith SGHWR Survey on experience of dismantling, decontamination and treatment of dismantled items in SGHWR. Gasoline cutting technology (effective for cutting thick plate) was introduced in dismantling of "Fugen". May 4 to Jul 30, 2010 Winfrith SGHWR Survey on the technology applied in SGHWR and experience, knowledge or safety related information on treatment of dismantled objects, mainly focusing on the processing flow of dismantled waste. Mar. 15 to Jun.29, 2012 Jun. and Oct Sellafield WAGR (Windscale) France : SPX, PX UK : Dounreay site Survey on experience and knowledge on remote dismantling technology of WAGR core and dismantling work. Survey on experience of decommissioning of sodium cooled fast reactor, especially concerning to fuel unloading and fuel washing, residual sodium treatment etc.. 2. Reflecting the experience of light water reactors Mid-level staff are dispatched to learn the experience of decommissioning of the light water reactor plant in Japan such as dismantling work of facility and plan management. Staff (including retired) from manufacturers or electric power companies are newly employed to teach and train JAEA staff.

14 26 reference material Step of Fugen Reactor Dismantling Procedure 27 STEP 1 Preparation for Reactor Core Dismantlement Remote controlled dismantling machine Temporary pool STEP 2 Removal of upper shielding Upper iron-water shield R/B Reactor core STEP 3 Removal of components inside reactor core Calandria tank etc. STEP 4 Removal of lateral and lower shielding Completion of reactor core dismantling P/T etc. Core tank etc. Lateral iron-water shield Lower iron-water shield