AMSTRAMGRAM AMélioration de la Section Thermique de capture l’Américium 241 par Mesure intéGRAle dans MINERVE P. Leconte CEA (SPRC/LEPh) A. Gruel, B. Geslot CEA (SPEx/LPE) L. Mathieu CNRS/CENBG A. Plompen, P. Siegler IRMM NEEDS meeting, Paris, 07-08 january 2016

OUTLINE Context Design of the experimental program Preliminary results Conclusions CEA | 10 AVRIL 2012

NEEDS Project CEA + IRMM + CNRS CONTEXT Collaborative framework NEEDS Project CEA + IRMM + CNRS Improvement of thermal capture xs of Am241 to solve integral vs microscopic inconsistencies CHANDA/WP12 Project CIEMAT + CEA + IRMM Work on samples of common interest for consistent measurement by TOF and oscillation techniques: Am241 and Tc99 I3P CEA + EDF + AREVA Improvement of nuclear data for the validation of the APOLLO2/JEFF3.1.1 code package NEEDS meeting, Paris, 07-08 january 2016

Current status of evaluations and covariances CONTEXT Current status of evaluations and covariances 99Tc thermal capture 241Am thermal capture JEF-2.2 19.1 b 22.8 ± 1.2 b ENDF/B-VII.0 JEFF-3.1 22.8 b 20.0 ± 1.2 b ENDF/B-VII.1 JEFF-3.2 21.0 b 23.6 b JENDL-4.0 241Am and 99Tc capture are involved in several situations Reactivity of MOX assemblies (Am) Cycle length (both) Burn-Up Credit (both) Both isotopes show differences higher than 5% on the thermal value NEEDS meeting, Paris, 07-08 january 2016

OUTLINE Context Design of the experimental program Preliminary results Conclusions CEA | 10 AVRIL 2012

DESIGN OF THE EXPERIMENTAL PROGRAM Sample availability Samples from IRMM (Geel, Belgium) 7 americium oxide in Al2O3 matrix + 3 « dummies » (Al2O3 only) 10 technetium oxide (without matrix) Samples from past MINERVE programmes Burn-Up Credit (natUO2 + 99Tc) OSMOSE (natUO2 + 241Am)  30 mg 241Am / sample  1g 99Tc / sample 10 cm 1 cm  2g 99Tc  60 – 200 mg NEEDS meeting, Paris, 07-08 january 2016

DESIGN OF THE EXPERIMENTAL PROGRAM Core configuration Main goal Highest precision (so sensitivity) on the thermal capture cross-section of 241Am and 99Tc Target uncertainty on integral capture cross section: <3% Reactivity worth measurements by the pile-oscillation technique  Mesurements in an over-thermalized spectrum Lattice with a water hole at the center New configuration of the MINERVE reactor Exp. zone: MAESTRO AMSTRAMGRAM NEEDS meeting, Paris, 07-08 january 2016

Overall reactivity worth energy distribution DESIGN OF THE EXPERIMENTAL PROGRAM Sensitivity calculations Overall reactivity worth energy distribution NEEDS meeting, Paris, 07-08 january 2016

DESIGN OF THE EXPERIMENTAL PROGRAM Experimental techniques Lattice neutronic characterization Activation foils (Au, In, Ni…) (238U capture rate / total fission) ratio γ-spectrometry on fuel pins around the water hole Integral xs measurements Oscillations (reactivity effect) Neutron activation (capture rate measurement) Fission cross section ratio measurements 241Am/235U -> special fission chambers with absolute mass deposit calibration NEEDS meeting, Paris, 07-08 january 2016

DESIGN OF THE EXPERIMENTAL PROGRAM Mechanical design So… … heterogeneous designs … have to fit in a single common device … in which we can pile-up samples … that must be easy to handle … and must remain watertight  watertight sample holder + aluminum wedges for axial positionning  new oscillating rod larger diameter, watertight  new central device aluminum cylinder NEEDS meeting, Paris, 07-08 january 2016

DESIGN OF THE EXPERIMENTAL PROGRAM Mechanical design Am and calibration samples New containers for: void samples (ref.) Al2O3 samples (ref.) Calibration samples + Al wedges of differents sizes NEEDS meeting, Paris, 07-08 january 2016

DESIGN OF THE EXPERIMENTAL PROGRAM Mechanical design Tc samples New containers for: void samples (ref.) + special Al wedges of different sizes

DESIGN OF THE EXPERIMENTAL PROGRAM Mechanical design Calibration samples To avoid the determination of absolute reactivity worrth, all measurements are normalised with calibration samples  Must be neutron standard isotopes + to fullfill our mechanical constraints must be: easy to manufacture as metallic foils not too expansive… Gold Usually used in past programs Easy to manufacture Easy to handle Other isotope ? Lithium was chosen NEEDS meeting, Paris, 07-08 january 2016

DESIGN OF THE EXPERIMENTAL PROGRAM Neutronic design 1st step: critical configuration Find the number of fuel elements that will fullfill all safety criterias keff all absorbers out Control rods reactivity worth keff of exp. lattice surrounded by graphite %fission in breeding zone 3 types of fuel assemblies 3% UO2 fuel pins 90% and 93% MTR assemblies Keep as possible the core symmetry  Based on MCNP calculations NEEDS meeting, Paris, 07-08 january 2016

DESIGN OF THE EXPERIMENTAL PROGRAM Neutronic design 2nd step: samples reactivity worth Range of measurement Δρ ≈ 1 to 10 pcm Typical uncertainty of ±0.01 pcm MC direct calculations  numerical CV ≈ 3 pcm on keff For Am and Tc MCNP calculations for safety purposes (no choice in the masses) Results were controled with the newly implemented IFP-perturbation method in TRIPOLI4 For Au and Li Calculations for mass determination  MC T4 IFP calculations NEEDS meeting, Paris, 07-08 january 2016

DESIGN OF THE EXPERIMENTAL PROGRAM Neutronic design Reactivity worth of samples IRMM samples 7 241Am containers MCNP, direct calculation: -2.1 ± 3 pcm TRIPOLI4, IFP-perturbation calculation: -2.08 ± 0.02 pcm 10 99Tc containers MCNP, direct calculation: -18.4 ± 3 pcm Calibration samples (10 mm) 7 natAu disk (thick. 0.25 mm) TRIPOLI4, IFP-perturbation calculation: -11.7 ± 0.2 pcm 7 natAu disk (thick. 0.125 mm) TRIPOLI4, IFP-perturbation calculation: -6.4 ± 0.1 pcm 5 natLi disk (thick. 0.6 mm) TRIPOLI4, IFP-perturbation calculation: -10.6 ± 0.2 pcm 7 natLi disk (thick. 0.2 mm) -5.9 ± 0.1 pcm NEEDS meeting, Paris, 07-08 january 2016

OUTLINE Context Design of the experimental program Preliminary results Conclusions CEA | 10 AVRIL 2012

PRELIMINARY RESULTS (1/2) 241Am results NEEDS meeting, Paris, 07-08 january 2016

PRELIMINARY RESULTS (2/2) 99Tc results NEEDS meeting, Paris, 07-08 january 2016

OUTLINE Motivation for new measurements on Am and Tc Design of the experimental program Preliminary results Conclusions CEA | 10 AVRIL 2012

AMSTRAMGRAM: a challenging program CONCLUSIONS AMSTRAMGRAM: a challenging program Unusual sample size and mass Lots of mechanical devices to design (most of them from scratch)  Experiments are ongoing till end of february A future experimental phase is under consideration Supplying of an Am241 source for neutron activation experiment Manufacturing of a flat fission chamber for capture and fission measurements with the same sample A possible extension to the fast energy range with TAPIRO (ENEA) Transport of Am caps to TAPIRO for neutron activation experiments NEEDS meeting, Paris, 07-08 january 2016