1. 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, january 2016

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

3. 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, january 2016

4. 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, january 2016

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

6. 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 (natUO Am)
 30 mg 241Am / sample
 1g 99Tc / sample
10 cm
1 cm
 2g 99Tc
 60 – 200 mg
NEEDS meeting, Paris, january 2016

7. 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, january 2016

8. Overall reactivity worth energy distribution
DESIGN OF THE EXPERIMENTAL PROGRAM
Sensitivity calculations
Overall reactivity worth energy distribution
NEEDS meeting, Paris, january 2016

9. 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, january 2016

10. 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, january 2016

11. 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, january 2016

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

13. 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, january 2016

14. 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, january 2016

15. 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, january 2016

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

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

18. PRELIMINARY RESULTS (1/2)
241Am results
NEEDS meeting, Paris, january 2016

19. PRELIMINARY RESULTS (2/2)
99Tc results
NEEDS meeting, Paris, january 2016

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

21. 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, january 2016