SINBAD ABSTRACT NEA-1517/78
NAÏADE 1 Graphite Benchmark (60cm)
1. Name of Experiment:
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Fontenay aux Roses 60cm NAÏADE 1 Graphite Benchmark
2. Purpose and Phenomena Tested:
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Determination of the fission neutron transport in graphite for penetration
up to 50 cm for the fast neutrons and up to 120 cm for the thermal neutrons.
3. Description of the Source and Experimental Configuration:
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The source is a fission plate irradiated by a beam of purely thermal neutrons
coming from the graphite reflector of the ZOE heavy water reactor located in
France at Fontenay aux Roses. The plate is 1 square meter and the thickness
of the fissile part is 2 cm. It consists of 9 square tiles 0.333 m along the
side, made of natural uranium claded with 1 mm of aluminum. Behind the fission
plate, which generates fission neutrons, there is a large experimental area
(27 cubic meter) in which the graphite block is placed. A boral screen
separated the fission plate from the experimental area to avoid thermal
neutron backscattering. The graphite block thickness was 140 cm and its
section was 2.00m x 2.00m enclosed in a steel frame 1 cm in thickness and
surrounded by a concrete shield.
The absolute fission neutron source distribution is determined by Monte Carlo
calculation (TRIPOLI 4) using the thermal neutron flux measurements (Mn-55)
for the source term. This determination take into account all fissions (U-235
and U-238) provided by the neutron diffusions in the converter itself, in
structures and in the mock-up (sub critical system with a source of thermal
neutrons). In this experiment, the diaphragm diameter was 60 cm. In the
graphite block a central hole of diameter 5cm can be stopped up with graphite
plugs of various thicknesses; the irradiated dosimeters are positioned
between the plugs.
4. Measurement System and Uncertainties:
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The following detectors were used:
1. S-32(n,p)
2. Rh-103(n,n’)
3. P-31(n,p) (2 sets of measurements)
4. 3 sets of measurements with silicon diodes (WIGNER effect)
5. Mn-55(n,gamma) under cadmium
6. Mn-55(n,gamma) (bare metal)
7. 2 sets of measurements using Au-197(n,gamma) under cadmium, one at short
distance, the other at longer distance with overlap
8. 2 sets of measurements using the In-115(n,gamma) under cadmium.
All dosimeters were calibrated in well known fluxes depending on their
characteristics: Maxwellian thermal flux at 27°C in a reference block,
fission spectrum with correction tacking into account the diffusion effects
altering slightly the pure fission spectrum, constant flux per unit of
lethargy.
The graphite specific gravity was 1.65 g/cm3. Measurements were carried out
to determine the absorption cross-section for thermal neutrons by the
graphite used in this experiment.
The precision of the fission plate power varies between 1% when the measurements
are made close together in time (a few days) and 5% when the measurements are
separated by several months. During the dosimeter irradiation, the observed
stability is (delta P)/P = 0.5%. The dosimeter position uncertainty estimated
by the experimental team itself is ±0.1cm.
Note of the data compiler:
It is possible to provide an estimation of the total dispersion (reactor
power, detector position and calibration, counting) of several conventional
fluxes because some measurements have been made during successive irradiations
at the same location and for the same detector (P-31, Silicon diodes, In-115/Cd).
We found:
- Total dispersion on P-31: ±7.5%
- Total dispersion on silicon measurements ±4.2%
- For the In-115/Cd dosimeter, 80% of the measurements lead to a dispersion
less than ±3% and one measurement gives ±22%.
5. Description of Results and Analysis:
-----------------------------------
All results are expressed in conventional fluxes. (Equivalent fission flux,
flux per unit of lethargy, equivalent thermal flux at 2200m/s). The
corresponding mean cross section or integral of resonance are given. The
measured experimental results are given on the converter axis for several
distances. A calibrated dosimeter reassessment resulting from the nuclear
data improvements was made recently (2003-2004) and published.
The interpretation using the French CEA Monte-Carlo code TRIPOLI 4 was made
on this graphite benchmark. A background noise evaluation was also determined
using at the same time TRIPOLI 4 calculations and fast and epithermal neutron
flux measurements without converter plate. The two corresponding input data
sets are included.
6. Special Features:
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None
7. Author/Organizer
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Experiment and Analysis:
M. Lott, P. Pepin, L. Bourdet, G. Cabaret, J. Capsie, M. Dubor, M. Hot,
C Goulet;
CEA (French Atomic Energy Commission), DPA/DEP/SEPP,
92260 Fontenay aux Roses
France
Compilation of data for Sinbad and experiment interpretation using TRIPOLI 4:
J.C. Nimal
CEA Centre de Saclay DEN/DM2S/SERMA/LEPP,
91191 Gif sur Yvette Cedex; France
Reviewer of compiled data:
I. Kodeli
OECD/NEA, 12 bd des Iles, 92130 Issy les Moulineaux, France
8. Availability:
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Unrestricted
9. References:
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[1] M. Lott, P. Pepin, L. Bourdet, G. Cabaret, J. Capsie, M. Dubor, M. Hot,
C. Goulet: Etude expérimentale de l’atténuation des neutrons dans
différents matériaux de protection à l’aide du dispositif NAÏADE I du
réacteur ZOE, Note CEA 1386, Dec. 1970
[2] J. Brisbois, M. Lott, G. Manent:
Mesure des flux de neutrons thermiques intermédiaires et rapides au moyen
de détecteurs par activation, Rapport CEA R 2491, August 1964.
[3] J.P. Both, Y.K. Lee, A. Mazzolo, O. Petit, Y. Peneliau, B. Roesslinger,
M. Soldevila: TRIPOLI-4 – A Three Dimensional Polykinetic Particle
Transport Monte Carlo Code, SNA’2003, Paris, September 2003.
[4] J.P. Both, A. Mazzolo, Y. Peneliau, O. Petit, B. Roesslinger:
Notice d’utilisation du code TRIPOLI-4.3 : code de transport de particules
par la methode de Monte Carlo, rapport CEA-R-6043, 2003.
[5] J.P. Both, A. Mazzolo, Y. Peneliau, O. Petit, B. Roesslinger:
User manual for version 4.3 of the TRIPOLI-4 Monte Carlo method particle
transport computer code, rapport CEA-R-6044, 2003.
[6] J.C. Nimal: Nouvelles interprétations des expériences NAÏADE 1, 1ere
Partie : Expériences sur le fer et le graphite, rapport NEA/NSC/DOC(2005)15,
JT00194885, 25-Nov-2005.
[7] J.C. Nimal: New interpretation of the NAÏADE 1 experiments, Part 1: the
Iron and Graphite Experiments,
Report NEA/NSC/DOC(2005)15, JT00194842, 24-Nov-2005.
[8] J.C. Nimal: New interpretation of NAIADE benchmarks,
Proc. ANS 14th Biennial Topical Meeting of the Radiation Protection and
Shielding Division, Carlsbad, New Mexico, USA. April 3-6, 2006
10. Data and Format:
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DETAILED FILE DESCRIPTIONS
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Filename Size[bytes] Content
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1 naiade-c.htm 9.234 This information file
2 NSCDOC_2005_15 EN.pdf 2.170.594 Description of Experiment, Ref. [7]
3 NSCDOC_2005_15 FR.pdf 1.084.441 Description of Experiment, Ref. [6] (in French)
4 RPSD2006-JCN.pdf 578.237 Ref. [8]
5 naiadegraph_60_fission.data 53.319 TRIPOLI 4 input (direct flux)
6 bruitdefond_graphite_60_fission.data 54.827 TRIPOLI 4 input (background scattering)
SINBAD Benchmark Generation Date: 12/2006
SINBAD Benchmark Last Update: 12/2006
