CBBI-13: Thirteenth International Workshop on Ceramic Breeder Blanket Interactions 30 Nov 2 Dec 2005 Fess Parker DoubleTree Resort Santa Barbara, CA, USA Present status of fusion neutronics activity and comments to neutron diagnostics for TBM KENTARO Ochiai JAEA Fusion Neutronics Group
What is my role in CBBI? Actually, I was not clear. However, I got a nice chart from Dr. Calderoni and his description inspired me. So, I will mention about the present status of the fusion neutronics. Also I will suggest the plans of the TBM neutronics instruments due to obtain the nice discussion after my presentation.
PRESENT STATUS OF FUSION NEUTRONICS (Breeding blanket Expr.) We have currently conducted some blanket neutronics benchmark experiments. Li2TiO3 JAEA/FNS DT neutron source 350 450 450 F82H/Water Beryllium (100) TBM (JP-WC type) benchmark experiment Tritium production rate in 40% enriched Li2TiO3 layer
TBM-HCPB NEUTRONICS EXPERIMENT TBM-HCPB experiments have also carried out in cooperation with EU under IEA sub-task. TPR measurements by Li2CO3 pellets (nat. Li) ENEA, TUD, JAERI Neutron flux in the central Be layer (ENEA) Neutron & γ-ray spectra behind the breeder unit (TUD/Rossendorf) 12 pellets (2mm thick) in each position to measure the TPR gradient across the ceramic breeder layer Irradiation started in Apr. 2005 at FNG, Y n =5.83x10 15 n
PRESENT STATUS OF FUSION NEUTRONICS (Plasma diagnostics) Some irradiation test of detectors has been done by DT neutron generator. Main three instruments will install in ITER to monitor 14MeV neutron spectrum. 1. Radial and Vertical Neutron Camera (Stilbene) 2. Fission chamber 3. Foil activation system Irradiation tests of the NC and FC have been performed by the JAEA/FNS and ENEA/FNG. NC-prototype has installed into JT-60 and it has been used for the measurement of DD neutron power (Surely, JET also).
And then, how about present status of ITER-TBM neutron diagnosis? NOTHING IS DECIDED YET!!! We must consider it immediately about the insertion to ITER TBM-port. From our neutronics experiments, I believe that it is not difficult to think about the conceptual design of TBM neutron diagnostics.
What are the objectives of neutronics tests in the Test Blanket Module? In order to monitor and verify the following issue, TRITIUM PRODUCTION RATIO SHIELDING, ACTIVATIONS EFFECTS DOSE ESTIMATIONS NUCLEAR HEATING IRRADIATION EFFECT, 10-2 10-3 10-4 TPR detector #1 Decay heal Shield Nucl. Heat Diagnostics we need to measure the neutron flux in the energy range of 10-2 -10 7 ev. 10-5 Neutronics of TBM φ neutron 2 (,,,, ) [ neutron / cm / sec/ ln E] x y z E t 10-6 10-8 10-6 10-4 10-2 10 0 Neutron Energy [MeV]
CHARACTERS OF TBM, ITS SURROUNDINGS Solid TBM will be inhomogeneous module It means the abrupt change of spatial distribution of neutron field. The surroundings are under higher temperature, Under huge neutron and gamma-ray fields, Under higher magnetic field. It means that some sensitive instruments can never use in the TBM. For example scintillation counter, BF3, He-3 detectors, Li-glass detecotor and so on (It is crazy!!!) Therefore, the available detectors are decided necessarily. They are fission chamber and activation foil system. Of course, the use is possible the device mentioned above if is out of a TBM like a neutron camera. The necessity is due to TBM. I can not understand now.?
Possibility of measurement of φ n (x,y,z,e,t) by fission chamber and activation foils Can we obtain the φ n (x,y,z,e,t) by only FC and AF? In principle, it is OK. But some examination will be needed. Time dependency U-238 and U-235 fission chambers should be used. Foils with capsule Energy distribution Multi foil activation method can measure. However, it will be necessary to performed the examination with DT neutron source and assembly. Spatial distribution About this one, we should discuss in depth. 1. Pneumatic tube syste (Activation foils) 2. Fission Chamber (U-235 and 238)
Spatial distributions of slow neutron in TBM Spatial distributions of slow neutron in TBM is very complicated. Reaction rate [10-24 / sour ce neut r on/ nucl eus] 10-4 10-5 10-6 10-7 Fast neutron Al 27( n, a) Nb93( n, 2n) I n115( n, n' ) I n115( n, 2n) Cr 52( n, 2n) Fe54( n, a) Li 7( n, n' a) T - 50 0 50 100 150 200 250 300 350 posi t i on [ mm] React i on r at e [ 10-24 / sour ce neut r on/ nucl eus] 10-1 10-2 10-3 10-4 10-5 10-6 Be-layer Slow neutron Spatial neutron distributions in TBM Li-layer (,g) Cr 50( n, g) Mn55( n, g) W186( n, g) Li 6( n, a) T -50 0 50 100 150 200 250 300 350 position [mm]
Neutron flux perturbation and streaming At least, we will need some points in front and rear sides to measure the spatial distribution. However, the number of line for the neutron measurement depend on the nuclear design. Maybe, we should calculate the effect by the perturbation and streaming and should carry out the experiments. φ slow(x, E) TBM Pneumatic tube for MFA Fission chamber Neutron streaming
Summary The current researches about fusion neutronics were introduced. For the neutron diagnostics in TBM, we showed the meanings of the TBM neutron diagnostics and proposed the activation foil method and fission chamber. Also, we pointed out that the examination of the perturbation and streaming effects are needed in future.
A comment about the timing of TBM insertion into ITER Before day first (H-plasma), we should calibrate the detector system by using compact DD and DT sources GENIE 36 by Sodern (Fr.) Compact DD and DT neutron generators
Hints to What measurements are needed to meet the objectives? All Instruments will be required the toughness against the heat, high intense irradiation and magnetic fields. 14MeV neutron MeV neutron kev neutron ev neutron Time resolution φ n(t) Spatial distribution φ n(x,y,z) Candidate methods of the ITER-TBM neutronics measurement Plasma diagnostics inside TBM Shield behind TBM Remarks Spectrometers Water (N-16γ) U238 FC (Th-232) Multi- foil Activ. Spectrometers Multi- foil Activation. U238 FC (Th-232) Multi- foil Activation. U235-FC Li-pellet. U235-FC msec~sec : Spectr. sec~ : FC hour ~ by Foils Multi-channel spectrometer for the source spectrum Water (N-16γ) Multi-foil Activ. U238 FC Calorimeter Multi-foil Activation Calorimeter Multi- foil Activation U235-FC Li-pellet Li-pellet. Gas outlet msec~: FC hour~: Foils Multi- foil Activation Water (N-16γ) Activat. Sys. U-238 FC TLD FC Multi-foil Activation Activation U235-FC Li-pellet In TBM, Spectrometer will not be available. Calorimeter system is not Tritium production (n,γ) decay heat and dose rate Activations Tritium production Gamma estimation for dose Order of time resolution in TBM neutrons should be discussed in detail. Activation methods and FC are prospective candidate instruments.