Neutronics experiments for validation of activation and neutron transport data for fusion application at the DT neutron generator of TU Dresden

Transcription

1 Neutronics experiments for validation of activation and neutron transport data for fusion application at the DT neutron generator of TU Dresden A. Klix1, A. Domula2, U. Fischer1, D. Gehre2 1 Karlsruhe Institute of Technology, Institute for Neutron Physics and Reactor Technology 2 Technische Universität Dresden, Institute for Nuclear and Particle Physics INSTITUTE FOR NEUTRON PHYSICS AND REACTOR TECHNOLOGY KIT University of the State of Baden-Wuerttemberg and National Research Center of the Helmholtz Association

2 Outline 2 Brief comments on history of the lab Context of the fusion-related experiments Recent blanket mock-up experiments Experiments for validation of activation cross sections Future work

3 Very brief history of the laboratory New neutron laboratory of TUD was constructed in the early 2000s Successor of the neutron laboratory of TUD located in the city of Pirna-Copitz Neutron generator: DD operation since 2004, DT operation since Rossendorf Pirna Dresden

4 Neutron Generator TU Dresden Accelerator: 300 kv, 10 ma up to 1012 n / s continuous or pulsed operation (accelerator prepared for ns pulsing) fixed and rotating T-Target Targets: Tritium: 3, 30, 250 Ci Deuterium 4

5 Overview of experimental activities 5 Experiments related to the development of nuclear fusion power plants (previously EFDA-Tasks, currently mostly F4E-Grants) - Checking of activation data (EAF): Irradiation of materials relevant for fusion reactors and comparison with EASY calculations - Testing of neutron transport data (FENDL, JEFF): Irradiation experiments of mock-ups of the European Test Blanket Modules for ITER - Development of instrumentation for future neutronics experiments with the TBM in ITER and for fusion reactor diagnostics Activation experiments and cross section measurements for development of instrumentation for neutrinoless double beta decay experiments Measurement of cross sections around 14 MeV and at 2.5 MeV (for astrophysics, nuclear fusion and geology) Collaboration with Universities of Vienna (Toni Wallner) and Heidelberg Experiments to determine soft error characteristics in electronics

6 Objective of ITER TBM mock-up and activation experiments Important nuclear parameters for fusion reactor blankets Tritium production rate / Tritium breeding ratio Nuclear heating Shielding capabilities Material activation Gas production others Neutronics calculations based on nuclear data libraries Input for the physical design of the blanket (with iterations) Proof of suitability and applicability of available transport codes and nuclear data for predicting such responses: 6 Physical design System operation Licensing Maintenance Decommissioning others Calculation +/- Uncertainty to be compared with Experiment +/- Uncertainty

7 TBM mockup experiments with neutron generators Example: Helium Cooled Pebble Bed (HCPB) TBM 7

8 HCLL TBM mock-up experiment Tritium production rate cm T-Target of FNG 45. 0c m.6 34 cm Mock-up consists of layers of LiPb, Eurofer and polyethylene Detectors placed along the axis of the mock-up MCNP model: Detailed description of the neutron source and the detectors (Li2CO3 pellets and all LiF-TLD) 8

9 HCLL mock-up experiment: Set-up for the measurement of fast neutron and gamma-ray fluxes Left: NE-213 detector (1.5"x1.5 ") Right: Ti-T target of neutron generator Middle: Mock-up 9 Two measurement position have been used. Only one channel was present at a time.

10 HCLL TBM mock-up experiment Fast neutron flux spectra Pulse height spectra recorded with the NE-213 detector Unfolding with MAXED code, response matrix (validated at PTB) Calculations with MCNP5 and JEFF and FENDL-2.1 Normalization of unfolded spectra by fitting 14 MeV peak height 10

11 HCLL TBM mock-up experiment Gamma-ray flux spectra Pulse height spectra recorded with the NE-213 detector Unfolding with MAXED code and response matrix Calculations with MCNP5 and JEFF and FENDL-2.1 Normalization from neutron spectrum 11

12 Activation experiments for validation of EAF data Here: Titanium (F4E Grant 014 ES-AC) Activation behavior of fusion reactor materials central topic for safety-related issues and decommissioning Most induced activation from slow neutrons (cross sections large) and fast neutrons (many open reaction channels) Assessment of induced activities usually based on inventory codes and activation data libraries This work: 12 Activation of titanium with DT neutrons and comparison with calculated values from EASY-2007 (FISPACT and EAF-2007) for the isotopes contributing most to the contact dose rate Titanium contained in several materials in the blanket, for example Li2TiO3

13 Activation experiments for validation of EAF data Activation of Ti in reactor environment Calculation with FISPACT-2007 and EAF-2007 Assuming 1 year of irradiation with 1 MW/m 2 wall load (primary neutrons) Li2TiO3 important isotopes Sc, Sc, K recycling limit after about 3.2 yr hands-on-limit after about 17.7 yr Titanium only important isotopes 48Sc, 46Sc, 42K recycling limit after about 4.4 yr hands-on-limit after about 109 yr

14 Activation experiments for validation of EAF data Experimental conditions in neutron laboratory Irradiation of Ti sample in fusion peak field of DT generator Sample size: Irradiation time: 1 cm2 x 0.5 mm thick 2.46 hrs, fluence 5.41*1011 n/cm2 Measurement: -ray spectra at several times after irradiation with HPGe spectrometer Set-up Si detector (Monitor) Ti sample d-beam Tritium target 14 Monitor foil (Nb+Zr)

15 Calculated Neutron spectrum Neutron spectrum for FISPACT calculation obtained in two steps: 1. Energy distribution from DROSG (Energy depends on the angle relative to deuterium beam) 2. Neutron flux spectrum at sample location from MCNP calculation taking into account the tritium target geometry and materials Validation of the neutron spectrum done by comparing the measured activation ratio of a pair of Zr/Nb foils with the MCNP-calculated one This is of importance since the (n,d) reactions involved in the production of scandium isotopes have thresholds around 14 MeV 15

16 Results (titanium irradiation) Radio- Half-life nuclide 46 Sc d Eg (kev) / Ig / / 1.00 Reaction contribution (%) 46 C/E Ti(n,p)46Sc 46 Ti(n,p)46mSc IT 46Sc Ti(n,d)46Sc 47 Ti(n,d)46mSc IT 46Sc C/C (%) E/E (%) 25.1 (24.0) Sc d / Ti(n,p)47Sc 48 Ti(n,d)47Sc (49.2) Sc d / / / (10.0) 4.3 Ti(n,p)48Sc 49 Ti(n,d)48Sc - effective cross sections from EAF-2007 and EAF-2010 the same - in C/C column: black EAF-2007, green EAF

17 TBM neutronics experiments: - experimental conditions R&D work within F4E Tasks (F4E-2008GRT-09, GRT-056) and others Conditions in the TBM terribly bad for detectors / diagnostics - 109~1014 n/cm2s oc - Magnetic fields ~4 T - difficult access - little space Possible candidates: Aktivation foils, miniatur fission chambers, diamond detectors, silicon carbide detectors, self-powered neutron detectors 17

18 Preparation for experiments with Neutronics TBM in ITER Pneumatic sample changer for measurement of short-living isotopes (development of instrumentation for TBM experiments and cross section measurements for double-beta decay experiments as well as general cross section measurements) Transport tube Air intake Air exhaust D1/2 Detektors S1/2 Storage AK Aktivation end R1 Auxillary port Measurement room D1 D2 S1 S2 ZU DB Fan AB SB ZU Zuluft AB Abluft DB Druckbetrieb SB Saugbetrieb R1 AK Irradiation room 18

19 Aktivation foil spectrometer Pneumatic transport system (Rabbit system) Spectral neutronen flux density - Application of suitable (new) dosimetry reactions (short half-lives) - Testing of suitable measurement regimes - Testing of suitable gamma ray detectors (HPGe, CZT,...) - Demonstration of an automated system Status - Rabbit system designed in collaboration with Technical University of Dresden - Set-up of system in progress at neutronics laboratory of TUD - Search for suitable sets of foils for short measurement cycles and simultaneous activation measurement underway (i.e sec) 19

20 Selection of suitable materials and reactions 20

21 Disclaimer for parts of the work presented herein: This work, supported by the European Communities under the Contract of Association between EURATOM and Forschungszentrum Karlsruhe, was carried out within the framework of the European Fusion Development Agreement. The views and opinions expressed herein do not necessarily reflect those of the European Commission. 21