Progress on Fast Reactor Development in Japan

Transcription

1 Presented for Meeting of the Technical Working Group on Fast Reactors (TWG-FR) (45th Annual Meeting) Progress on Fast Reactor Development in Japan June 20-22, 2012 Hiroaki OHIRA, Nariaki UTO Japan Atomic Energy Agency (JAEA)

2 1 1. Experimental Fast Reactor JOYO Current Status and Future Plan of Joyo Mark-III

3 Experimental Fast Reactor Joyo 2 Attain Initial Criticality:1977 First Operation (MK-I; 50/75MWt; Breeder core) :1978/1980 ibid (MK-II; 100MWt; Irradiation core) :1983 ibid (MK-III; 140MWt; Upgraded irradi. core) :2004 Main Control Room Overview of Main Cooling Bldg. Rotating Plug Air Blower Role of Joyo To demonstrate the basic FBR technology To conduct irradiation of fuel and materials To validate innovative technologies for the development of future FR Apply to Monju JSFR

4 Safety of Joyo in case of a tsunami and blackout Joyo is located at 38 meters above sea level. The heat is released into air in the secondary loop finally. Decay heat can be removed by a natural circulation of sodium. Natural circulation 3 Location of Joyo Air 38m ~ Ocean Approx. 300m

5 Master Schedule of Joyo JFY MK-III 6 cycle 15 th Periodical Inspection Failure of the test subassembly disconnection In-vessel Visual Inspection Planning of UCS Replacement Work Manufacturing of New UCS and device for replacement UCS Replacement MARICO-2* Transfer pot MARICO-2* Retrieval Lifting-up test of MARICO-2* Manufacturing of MARICO-2* Retrieval Device Design of MARICO-2* Retrieval Device

6 5 2. Current Status of Monju

7 Main specifications and progress of Monju 6

8 Overview of System Start-up Test (SST) 7

9 Withdrawal of In-Vessel Transfer Machine (IVTM) 8 Auxiliary Handling Machine Gripper assembly Opening rod Closing rod 2010 Aug.26 Nov.16 Dec.16 : Investigation and analyses on the IVTM drop : Outside observation on the area around guide tube connection : Planning of withdrawing IVTM with fuel throat sleeve drop IVTM Fuel throat sleeve Connecting part of the guide tube Rotating rack Control rod drive mechanism Shield plug Fuel handling machine 2011 May.24 Jun.24 Aug.29 Nov.11 : Start of withdrawal work : End of withdrawing IVTM with fuel throat sleeve : Restoration work at the upper part of the reactor : Completion of repair work of upper part of the reactor Core

10 Restoration situation of IVTM(Aug.29~Nov ) 9

11 10 Emergency safety countermeasures against Tsunami

12 Enhancement of safety countermeasures 11

13 Operation conditions in Station Black-Out (SBO) Reactor Building Containment Vessel» The main pumps of the primary and secondary main cooling systems are inoperable.» The blowers of AC are also inoperable and AC power supply is stopped in a big earthquake. Primary Main Circulation Pump Primary Sodium Intermediate Heat Exchanger N2 Gas Pump Shutdown Secondary Main Circulation Pump Secondary Sodium Air Cooler Air Cooler Outlet Stop Valve (Opened) Steam Generator Inlet Stop Valve (Closed) Air Cooler Blower Shutdown» The SG inlet stop valves are closed, and the AC outlet stop valves are opened just after the reactor scrum.» The pony motors are still operating by the emergency DGs. DG» However, SBO occurred by a huge Tsunami. seawater 12 Fuel Control Rod Guard Vessel Reactor Vessel

14 Cooling characteristics of primary and secondary heat transport system» Natural circulations of sodium in the primary and the auxiliary cooling systems were generated and removed the decay heat safely into the atmosphere. 13 Temperature (ºC) (a) Primary Heat Transport System Natural circulation RV outlet Forced circulation 度(350 )300 Pony motor 250 RV inlet restarted 200 Flow rate 地震発生津波来襲時間 ( 日 ) ディーゼル発電機 1 台復旧 Earthquake~SBO Time (day) 流量(80 % )温 Flow rate (%) Temperature (ºC) (b) Secondary Heat Transport System Forced circulation Natural circulation 度()350 AC inlet AC outlet Pony motor restarted 200 Flow rate 時間 ( 日 ) 地震発生 津波来襲 Earthquake~SBO Time (day) ディーゼル発電機 1 台復旧 流量(80 % )温 Flow rate (%)

15 14 Fuel handling and storage system» Spent fuels are transferred from the reactor to the Ex-Vessel Fuel Storage Tank (EVST), and then they are cleaned by water and transferred to the Spent Fuel Pool (SFP) after the decay heat reduces to lower enough level.» The evaluation of the cooling capability of EVST is much more important than that of SFP in Monju.

16 15 EVST and Fuel transfer pot

17 Temperature ( ºC ) Temperaruer (ºC) Cooling characteristics of EVST» The upper part of sodium temperature in the tank reduces gradually from the maximum temperature of approximately 260ºC» The maximum temperature was approximately 320ºC in the case of three loops natural circulation without power supply. Earthquake~SBO Upper region (A) Lower region (B) Flow Rate (A) Solid line : Without power supply (3 loop NC) 10 Dashed line : Power supply at 8.hours after SBO Time (h) ( hr ) Tmperature and flow in EVST [EVST] (B) Flow Rate (kg/s) Flow(kg/sec) 16

18 Temperature and water surface change in SFP 壁 Fuel transfer 燃料移送機レール machine s rail SF キャスク cleaning 洗浄ピット system 使用済燃料 SF キャスク詰 canning ピット system Fuel 貯蔵ラック rack Wall 壁 Fuel can Air Temperature ( ) ºC Water temp. Room temp. 110 days Time (day) Humidity 100% 70% 40% 0% 17 Fuel SA Water» The water temperature became constant value of approximately 70ºC.» It takes more than 3 months before the top of the can appeared in the gas region. Water height (m) Top of fuel cans days Time (day)

19 Evaluation for Severe Accident 18» Stress tests are being conducted for the following 7 issues based on the instruction by NISA dated July 22, 2011; (1) Earthquake, (2) Tsunami, (3) Combination of Earthquake and Tsunami, (4) SBO, (5) LUHS (Loss of Ultimate Heat Sink), (6) Combination of SBO and LUHS, and (7) Accident management.» These evaluations should be conducted on the damage or failure of the equipment or facilities with deterministic and realistic methods, and cliff-edges should be identified, which lead to a significant fuel damage.» Effectiveness of the countermeasures should be also investigated from the viewpoint of the defense-in-depth.

20 19 3. Fast Reactor Cycle Technology Development (FaCT Project) JSFR (Japan Sodium-cooled Fast Reactor) Design Study and R&D Progress

21 1977 *2 Joyo Experimental Steps to Commercialization of Fast Reactor in Japan *1: study performed *2: initial criticality attained -->Monju resumed in May, *2 Monju Prototype 1990s *1 DFBR Design for Demonstration FaCT Project Confirmation of FR Basic Technologies Verification of Safe and Stable Operation Power :50MWt 100MWt 140MWt (Mk-III Core) Temperature :435ºC 500ºC 500ºC JSFR Original plan (under review) Demonstration / Commercialization Innovative Technology for Economics and Reliability Design Study of Demonstration Reactor Development of Element Technologies Power : 1,600MWt / 660MWe Temperature : 550ºC Demonstration of Reliable Operation Establishment of Sodium Handling Power :714MWt / 280MWe Temperature : 529ºC System Development as Electricity Generation 20

22 Framework of Promoting the FaCT Project 21 Atomic Energy Commission (AEC) Ministry of Economy, Trade and Industry (METI) Ministry of Education, Culture, Sports, Science and Technology (MEXT) JAEA Core Engineering Company (MFBR/MHI) Electric Utilities Manufacturers Universities, Research Organizations, etc.

23 Secondary pump Japan Sodium-cooled Fast Reactor (JSFR) SG Integrated pump-ihx Reactor Vessel Reactor Core Items Electricity output Thermal output Configuration Specifications 1,500 MWe 3,730 MWt Loop Number of loops 2 Primary sodium outlet temperature 550 degree C Reactor vessel material 316 FR stainless steel Piping material Mod. 9Cr-1Mo steel Plant efficiency Approx. 42% Fuel type Burn-up (ave.) for core fuel TRU-MOX Approx. 150GWd/t Breeding ratio Break even (1.03) ~ 1.2 Cycle length months or less, 4 batches

24 Output of FaCT Phase-I (JFY ) R&D results on innovative technologies and design studies for commercial FR cycle plants Evaluation results of each innovative technology applicability to the commercial FR cycle plants Evaluation results of the degree of achievement toward the development targets for the commercial plants to confirm the direction of R&D plans toward the next stage 23

25 Evaluation Results of Innovative Technologies for Reactor System 9 of 10 technologies are suitable for installation to the demo./commercial reactors. ODS steel will be further evaluated on manufacturing with stable quality. Plant constituent parts Key technologies Safety SASS, re-criticality free core Core and Fuel High burn-up fuel with ODS cladding material Reactor System Compact reactor system Two-loop cooling system of large diameter piping made of Mod. 9Cr-1Mo steel Cooling System Integrated IHX/Pump component Highly Reliable SG with double-walled straight tube DHRS Natural convection DHRS BOP Simplified fuel handling system CV made of steel-plate-reinforced concrete (SCCV) Reactor Building Advanced seismic isolation system for SFR : adoptable, : further R&D needed for judgment, No: not adoptable 24 24

26 New Framework for Nuclear Energy Policy Status of Energy Policy Making Innovative Strategy for Energy and the Environment New Basic Energy Plan 25 Nation-wide discussion on desirable energy mix Interim Compilation (Nuclear fuel cycle options, FRs) Interim Compilation (Nuclear fuel cycle costs) Alternatives for innovative strategy for energy and the environment Cost review committee report Alternatives for the bestmix of energy sources Basic principle on the best-mix of energy sources AEC New nuclear policyplanning council National Policy Council (Direct to the Prime Minister) Energy and Environment Council METI Advisory Committee for Natural Resources and Energy

27 Situation of National Policy Making and FaCT Project On July 19, 2011, JAEC decided to continue the FR cycle technology development program in the limited range of activities to contribute to international standardization (ex. safety criteria) and to maintain the technology base level until the determination of new nuclear energy policy. On Sept. 27, 2011, JAEC restarted the deliberation process for newframework for Nuclear Energy Policy. - The process was suspended after the Fukushima NPS accidents. -Major issues: Safety, Cost, Nuclear Power and Fuel Cycle Options, Waste Management, International Perspectives, R&D planning, etc. -The process has been carried out to determine the new Framework with the relationship to new governmental energy/environmental policy making. On Dec. 21, 2011, Energy and Environment Council complied Basic guideline toward Presentation of Alternatives regarding the Strategy for Energy and the Environment. In the FaCT project, focus has been on further improvement on safety of next generation SFRs based on lessons learned from the Fukushima NPS accidents. 26

28 Safety Goals for the Gen-IV Systems and Defence-in-Depth Levels GIF Goals Levels of DiD Plant state SR-1: Operational Safety and Reliability SR-2: Low likelihood and degree of CDA SR-3: Elimination of need for offsite emergency response (in Design) Level-1: Prevention of abnormal operation and failures Level-2: Control of abnormal operation and detection of failures Level-3: Control of accidents within the design basis Level-4: Control of severe plant conditions, including prevention of accident progression and mitigation of severe accidents IAEA SSR 2/1(Revised NS-R-1) Normal operation Anticipated operational occurrence(aoo) Design basis accidents (DBA) Design extension conditions(dec) -including significant core degradation - Level-5: Mitigation of radiological consequences of significant releases of radioactive materials corresponds to offsite emergency response - 27

29 Reflection of Lessons Learned from Fukushima NPS Accidents (1/2) Because of the wide area earthquake as the design basis level and the following Tsunami over the design basis level, multi-units in Fukushima area lost all AC power supplies in long-term and resulted in the SA. Based on the DiD concept, it is necessary to prevent the significant radioactive material release, even under the extreme external events exceeding the DBA. The condition corresponds to the DEC in DiD level-4. For the SFR, the bleed and feed type accident management (AM) is not easy due to the sodium chemical reactivity. ==> Enhancements of appropriate provisions for prevention and mitigation of the SA in DiD level-4 are keys to achieve the high level safety in next generation SFR. 28

30 Reflection of Lessons Learned from Fukushima NPS Accidents (2/2) In the Japan government report to the IAEA, there are 28 key points in 5 categories as lessons learned from the accident. 10 out of 28 key points are able to be picked up as related issues for the reflection to the SFR safety design. Category 1: Strengthen preventive measures against a severe accident Strengthen measures against earthquakes and tsunamis Ensuring the water tightness of essential equipment facilities Ensure power supplies Ensure robust cooling functions of reactors and PCVs Ensure robust cooling functions of spent fuel pools Consideration of NPS arrangement in basic designs Category 2: Enhancement of response measures against severe accidents Enhancement of measures to prevent hydrogen explosions Enhancement of the radiation exposure management system at the time of the accident Enhancement of instrumentation to identify the status of the reactors and PCVs Category 3: Enhancement of nuclear emergency responses Category 4: Reinforcement of safety infrastructure Ensuring the independence and diversity of safety systems Category 5: Thoroughly instill a safety culture 29

31 30 Safety Measures in DEC For the next generation SFR, built-in measures against CDA is necessary to shutdown system, coolant system and/or containment system by effectively utilization of passive mechanisms.

32 Experiments for Severe Accident Measures Concept of the Experiments; Safety design policy for severe accident measures Measures for In-Vessel-Retention (IVR) have priority. For IVR, measures against LOHRS and ATWS should be reinforced. More attention to LOHRS (LOHS, LORL) should be paid after the Fukushima NPS accidents. Candidates of measures against LOHRS Alternative cooling system must be installed. External vessel cooling and internal vessel cooling systems are important candidates. Phenomena to be investigated for the measures Heat transfer and thermo-hydraulics in reactor vessel, from external vessel, and from steam generator Local heat removal characteristics from the damaged core 31

33 Material Test Reactor JMTR High Temperature Gas Reactor HTTR AtheNa Facility for SA experiments FBR Safety Facilities Sodium Thermal- Hydraulics Facility Experimental Fast Reactor JOYO AtheNa Oarai R&D Center Sodium Tech. Facility Thermal-Hydraulics Facility View of AtheNa facility 32 Construction period: Dimension: 130 m x 62 m x 55 m Total floor area: 11,000m 2 Electric supply : 7,000kVA Emergency generator: 1,250kVA Cranes : 120 & 100ton Sodium inventory : 260 ton 46m 66m 18m 55m 100t crane 120t crane ( ) ( ) S o d iu m L a b o ra to ry A b o u t 3, m 2 Sodium Tank Electric supply S o d iu m L a b o ra to ry Steam systems Sodium heater room Sodium Heater Sodium Tanks Cross section Steam systems Emergency generator 62m Electric supply room (with emergency generator : 1,250kVA) Electric supply Entrance Control Room[2F] Layout of AtheNa facility Control room

34 33 Appendix

35 Reflection of Lessons Learned from Fukushima NPS Accidents Lessons in Category 1: Strengthen preventive measures against a severe accident (1) Strengthen measures against earthquakes and tsunamis (8) Ensuring the water tightness of essential equipment facilities -For the External hazards -Due consideration of loss of all AC power supplies following the extreme external hazards -Seismic events may be accompanied by subsequent events -Provision of safety functions due to common cause failure by the external hazards (2) Ensure power supplies -For the Emergency power supply -Diversity to the extent practicable and redundancy for suppressing common cause failure including external events (3) Ensure robust cooling functions of reactors and PCVs -For the Decay heat removal -Decay heat removal systems for reactor cooling even under loss of all AC power supply -Utilization of passive heat removal capability for DEC -Diversity of ultimate heat sinks for decay heat removal (4) Ensure robust cooling functions of spent fuel pools (7) Consideration of NPS arrangement in basic designs -For the Fuel storage systems -Heat removal & status monitoring even under loss of all AC power supplies -Effect of flooding water contained in storage pool during severe accident 34

36 Reflection of Lessons Learned from Fukushima NPS Accidents Lessons in Category 2: Enhancement of response measures against severe accidents (9) Enhancement of measures to prevent hydrogen explosions -For the Control of containment conditions -Prevention/Mitigation of the sodium fire and sodium-concrete reaction, and Due consideration of the challenges on the integrity of containment (12) Enhancement of the radiation exposure management system at the time of the accident (14) Enhancement of instrumentation to identify the status of the reactors and PCVs -For the Means of monitoring -Adequate monitoring for radiation, coolant level, pressure etc. in DEC 35 Lessons in Category 4: Reinforcement of safety infrastructure (26) Ensuring the independence and diversity of safety systems -For the Decay heat removal -Diversity to the extent practicable and redundancy for suppressing common cause failure including external events -For the Ultimate heat sink -Diversity of the ultimate heat sinks for the decay heat transfer

37 General safety research works for enhancement of SA measures 36 DHX Cooling DHX DHR System (Dipped/Penetrated Heat Exchanger in Upper Plenum) Flow path in inter-wrapper region by Dipped DHX Flow path in subassemblies and inter-wrapper regions via Penetration-type DHX Ex-RV Cooling Ex-RV DHR System GV Cooling System CV Cooling System Flow path in inter-wrapper region by Ex-RV cooling Flow path in RV-GV Gap region by Ex-RV cooling Flow path in lower plenum by Ex-RV cooling Convection heat transfer in vessel DHX heat transfer Convection heat transfer in vessel and gap Heat transfer in cooling tube Radiation Thermal conduction Points for heat removal experiments for SA evaluation