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2010 US-Japan Workshop on Fusion Power Plants and Related Advanced Technologies at UCSD CA, US, Feb.23-24, 2010 1 Commissioning scenario including divertor condition for Demo-CREST Thanks to collaboration with A.Hatayama, M.Ishida, K.Maeki(Keio University) Y.Ogawa, M.Nakamura(Univ. of Tokyo) Central Research Institute of Electric Power Industry(CRIEPI) Ryoji HIWATARI, Kunihiko OKANO

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US-JP Workshop on Fusion Power Plants and Related Advanced Technologies UCSD, in U.S,. 22-23 Feb. 2010 2 Contents Introduction : Importance of commissioning test in the fusion reactor Introduction : Importance of commissioning test in the fusion reactor Overview of Demo-CREST Operational space expansion by tritium ratio control Compatibility with the divertor heat load condition as for the new commissioning method Summary and future issues

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US-JP Workshop on Fusion Power Plants and Related Advanced Technologies UCSD, in U.S,. 22-23 Feb. 2010 Plant start-up and Commissioning Test Plant start-up step Focus on the first DT discharge period 3 Time (month) Fusion power (MW) Construction Non-nuclear test H, D discharge First DT discharge (Commissioning test period) Rating operation

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US-JP Workshop on Fusion Power Plants and Related Advanced Technologies UCSD, in U.S,. 22-23 Feb. 2010 Commissioning test for FBR According to DEMO and PROTO in fission reactors like Superphenix, commissioning test took about 9 month-operation period to carry out the final check on the heat removal system, the generation and the turbine system, safety system and so on. 4 Fig. Power buildup during Superphenix(FBR) commissioning test (J. Gourdon, et al., Nuclear Science and Engineering 106(1990)1-10)

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US-JP Workshop on Fusion Power Plants and Related Advanced Technologies UCSD, in U.S,. 22-23 Feb. 2010 5 Importance of Commissioning Operation Commissioning operation is essential to carry out the final verification for all components performance. For example, divertor plasma and blanket system can NOT be demonstrated in the plant scale during the ITER program. Divertor: The total power handling in DEMO becomes huge in comparison with ITER, and some sophisticated operation method has to be developed during the ITER project. Final demonstration of divertor plasma operation for DEMO has to be carried out by DEMO itself. Blanket system(including tritium self-sufficiency): How efficiently the total system (tritium production, power generation) can be examined is important under the limited amount of the initial tritium stock. Gradual increase of fusion power means the wide range of the power load condition of the first wall. Is such wide range operation for power load be possible under the single blanket system ?

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US-JP Workshop on Fusion Power Plants and Related Advanced Technologies UCSD, in U.S,. 22-23 Feb. 2010 6 Contents Introduction : Importance of commissioning test in the fusion reactor Overview of Demo-CREST Overview of Demo-CREST Operational space expansion by tritium ratio control Compatibility with the divertor heat load condition as for the new commissioning method Summary and future issues

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US-JP Workshop on Fusion Power Plants and Related Advanced Technologies UCSD, in U.S,. 22-23 Feb. 2010 7 Demonstration Plant : Demo-CREST Principles for the Demo-CREST Design Demonstration Phase : To demonstrate electric power generation as soon as possible in a plant scale, with moderate plasma performance which will be achieved in the early stage of the ITER operation, and with foreseeable technologies and materials (OP1 OP4) Development Phase : To show a possibility of an economical competitiveness with advanced plasma performance and high performance blanket systems, by means of replacing breeding blanket from the basic one to the advanced one (OP4, OPRS) Figure:Birds-eye of Demo-CREST CS Coil TF Coil PF Coil Blanket Maintenance Port Divertor Maintenance Port Cryostat Shield OP1OP2OP3OP4OPRS R (m) / A 7.25 / 3.4 q min /q 95 -/5.0-/5.23.6 / 6.5 NN 1.92.53.03.4 4.0 HH 0.961.11.2 1.4 fn GW 0.560.730.801.02 1.31 P b (MW) 188190185191 106 P f (MW) 1260194024602840 2970 P enet (MWe) Basic Blanket (30%) 30230390490 - Advanced Blanket(40%) --- 8501090

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US-JP Workshop on Fusion Power Plants and Related Advanced Technologies UCSD, in U.S,. 22-23 Feb. 2010 8 Commissioning Operation Points MHD and current drive have already been examined. Start with the plasma performance similar to ITER standard operation (OP1: N 1.9). Final operation point (OP4: N 3.4) is based on the ITER advanced operation. Consistency with divertor plasma has NOT been examined yet.

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US-JP Workshop on Fusion Power Plants and Related Advanced Technologies UCSD, in U.S,. 22-23 Feb. 2010 How about divertor compatibility ? Required impurity radiation power for divertor heat load less than 10MW/m 2 is evaluated by 2-point model Based on the ITER operation condition for divertor plasma, Demo-CREST OP1 is hardly operational. 9 Large gap

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US-JP Workshop on Fusion Power Plants and Related Advanced Technologies UCSD, in U.S,. 22-23 Feb. 2010 10 Contents Introduction : Importance of commissioning test in the fusion reactor Overview of Demo-CREST Operational space expansion by tritium ratio control Operational space expansion by tritium ratio control Compatibility with the divertor heat load condition as for the new commissioning method Summary and future issues

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US-JP Workshop on Fusion Power Plants and Related Advanced Technologies UCSD, in U.S,. 22-23 Feb. 2010 Tritium ratio control during commissioning Key point for compatibility with divertor operation is low fusion (heating) power and high density operation. Tritium ratio (T-ratio) control is a candidate to do that In the simple definition, decrease of the tritium ratio enable to decrease of fusion power with constant ion density. Is this operation scenario possible ? 11

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US-JP Workshop on Fusion Power Plants and Related Advanced Technologies UCSD, in U.S,. 22-23 Feb. 2010 MHD & current drive analysis Consistency among profiles of pressure, plasma current, NBI deposition is analyzed by EQLAUS/ERATO and DRIVER88 from the view point of MHD stability(low n kink, high n ballooning, Mercia criterion), NBI current drive property 12 Plasma pressure profile Plasma current profile NBI injection profile Consistency total beam alpha thermal bootstrap current beam current total current (target (ERATE) : bold) total current (result ( DRIVER88 ): thin) injection region

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US-JP Workshop on Fusion Power Plants and Related Advanced Technologies UCSD, in U.S,. 22-23 Feb. 2010 Operational points without T-ratio cont. Operation points for N =1.8-3.4, I p =15.6MA and P NBI 200MW are shown. Rating operation point P f =3.0GW is around =1.0x10 20 m -3 P f =1GW with fn T =0.5 is around = 0.4x10 20 m -3, this operation point(similar to OP1) has higher P f and lower than ITER-SS(). 13 N =1.8 N =2.5 N =3.0 N =3.4

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US-JP Workshop on Fusion Power Plants and Related Advanced Technologies UCSD, in U.S,. 22-23 Feb. 2010 Operational space with T-ratio control Expand the higher density operation region with T- ratio control. 14

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US-JP Workshop on Fusion Power Plants and Related Advanced Technologies UCSD, in U.S,. 22-23 Feb. 2010 15 N =1.8 N =3.0 fn T =0.5 fn T =0.1 fn T =0.5 fn T =0.1 Low N has flexibility for T-ratio control Current profile

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US-JP Workshop on Fusion Power Plants and Related Advanced Technologies UCSD, in U.S,. 22-23 Feb. 2010 Operational points with T-ratio cont. T-ratio control (fn T =0.04)can reduce P f =0.3GW with higher =0.6x10 20 m -3 Operation point ( ) with P f 0GW and higher =0.8x10 20 m -3 also exists under the reduction of Ip from 15.6MA to 12.4MA Operational space expands to higher density region with T-ratio cont. 16

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US-JP Workshop on Fusion Power Plants and Related Advanced Technologies UCSD, in U.S,. 22-23 Feb. 2010 Plasma commissioning senario Operational route with T-ratio control starting from P f 0GW and higher =0.8x10 20 m -3 is preferable to the previous route without T-ratio control, from the view point of the divertor heat- handling condition. 17

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US-JP Workshop on Fusion Power Plants and Related Advanced Technologies UCSD, in U.S,. 22-23 Feb. 2010 18 Contents Introduction : Importance of commissioning test in the fusion reactor Overview of Demo-CREST Operational space expansion by tritium ratio control Compatibility with the divertor heat-handling condition as for the new commissioning method Compatibility with the divertor heat-handling condition as for the new commissioning method Summary and future issues

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US-JP Workshop on Fusion Power Plants and Related Advanced Technologies UCSD, in U.S,. 22-23 Feb. 2010 Compatibility with divertor plasma The divertor plasma condition(required radiation power for divertor heat load less than 10MW/m 2 &SOL density) of the new plasma commissioning scenario can start from similar condition to the ITER condition 19

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US-JP Workshop on Fusion Power Plants and Related Advanced Technologies UCSD, in U.S,. 22-23 Feb. 2010 High confinement is required To start from the DD plasma (fn T =0%), high confinement similar to ITER-SS(HH=1.57) is required. In case of Demo-CREST, NBI current drive power is also large( 200MW) 20 RIp fn GW PfP NBI HH NN f bs Tratio ITER SS 6.359.012.30.670.82356591.572.950.4850% Demo- CREST1 7.2512.414.30.770.89341961.571.850.360% Demo- CREST2 14.80.760.88101841.651.850.340% Demo- CREST3 14.80.750.8791731.711.850.340% Demo- CREST4 14.00.850.98102281.562.000.360%

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US-JP Workshop on Fusion Power Plants and Related Advanced Technologies UCSD, in U.S,. 22-23 Feb. 2010 21 Contents Introduction : Importance of commissioning test in the fusion reactor Overview of Demo-CREST Operational space expansion by tritium ratio control Compatibility with the divertor heat load condition as for the new commissioning method Summary and future issues Summary and future issues

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US-JP Workshop on Fusion Power Plants and Related Advanced Technologies UCSD, in U.S,. 22-23 Feb. 2010 22 Summary T-ratio control is proposed to make a new commissioning pass starting from the high and low Pf similar to ITER-SS for divertor heat handling in the Demo-CREST design. When Ip is reduced from 15.6MA to 12.4MA, a operation point with higher and lower Pf than ITER-SS is also found. It is found that T-ratio control has a good potential to establish the divertor plasma commissioning scenario to keep high and low Pf preferable for divertor heat handling in the commission phase.

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US-JP Workshop on Fusion Power Plants and Related Advanced Technologies UCSD, in U.S,. 22-23 Feb. 2010 23 Future Issues Sensitivity of operation parameter such as Ip, N on the operation space has to be analyzed more carefully. The detailed divertor analysis by SOLPS5.0 is now under way. Consistency between transport property has to be confirmed by using 1-D transport code.

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US-JP Workshop on Fusion Power Plants and Related Advanced Technologies UCSD, in U.S,. 22-23 Feb. 2010 Current profile 24 N =1.8 Temperature Density Pressure Current N =2.5 N =3.0

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US-JP Workshop on Fusion Power Plants and Related Advanced Technologies UCSD, in U.S,. 22-23 Feb. 2010 25 Required Radiation Power for Divertor The radiation power required for q div

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US-JP Workshop on Fusion Power Plants and Related Advanced Technologies UCSD, in U.S,. 22-23 Feb. 2010 26 Possibility of DT-ratio Control CREST(R=5.4m, N =5.5, Pf=3GW, Pcd=100MW) MHD with current drive consistency has been examined. BSC and Ip decrease, then confinement and density are degraded under the limited Pcd. DT-ratio control has still possibility for high density operation with decrease of fusion power in comparison with Demo-CREST results T/(T+D)=0. T/(T+D)=0.2 T/(T+D)=0. T/(T+D)=0. T/(T+D)=0. OP OP2 OP3 OP4 Analysis for Demo-CREST is now under survey.