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NAÏADE 1 Light Water Benchmark (60cm)

 1. Name of Experiment: 
    Fontenay aux Roses 60cm NAÏADE 1 Light Water Benchmark

 2. Purpose and Phenomena Tested: 
    Determination of the fission neutron transport in light water for penetration
    up to 50 cm for fast neutrons and up to about 150cm for thermal neutrons.

 3. Description of the Source and Experimental Configuration: 
    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 an aluminum tank is placed.
    In this experiment, the tank is filled with light ordinary water. A boral
    screen separated the fission plate from the experimental area to avoid
    thermal neutron backscattering. The water along the fission plate axis was
    250 cm deep. The square section of the tank was 250 cm x 250 cm. The tank
    is surrounded laterally by an ordinary concrete shield of thickness 80 cm
    (50 cm at the top).
    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 takes 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. The counter chambers were suspended from a steel section
    with precise position (accuracy 0.1cm). The dosimeter foils were fixed to
    Plexiglas rods.

 4. Measurement System and Uncertainties: 
    The following detectors were used:
     1. Phosphorus dosimeters (P-31(n,p) reaction)
     2. Rhodium dosimeters (Rh-103(n,n’) reaction)
     3. Silicon diodes (Wigner effect)
     4. Sulphur dosimeters (S-32(n,p) reaction)
     5. Equivalent dose rate measurements using photomultiplier
     6. Indium 115 covered with cadmium ((n,gamma) reaction)
     7. Gold deposit Au-197 covered with cadmium ((n,gamma) reaction)
     8. BF3 chamber covered with cadmium
     9. Mn-55 foils covered with cadmium ((n,?) reaction)
    10. Bare BF3 counter up to 180cm
    11. Bare Mn-55 foils ((n,gamma) reaction)

    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.

    All experimental results were given with a ZOE reactor power equal to 100kW.
    The power stability and reproducibility were checked using a boron carbide 
    gamma-compensated ionization chamber and Mn55 dosimeters placed on a rod located
    before the fission plate. Then, 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 ?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 (S32, Silicon diodes, BF3 chamber). We
    - Total dispersion on silicon diode measurements: ±0.6% with three times 2 or
      3 measurements separated only by 2 days.
    - Total dispersion on S32 fluxes: ±3% with twice 2 measurements separated by
      1 week.
    - Total dispersion on BF3 counter measurements (X<130cm): ±9.4% with 8 times 
      2 measurements separated by 3 years.

 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 2200 m/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 light water 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: 

 7. Author/Organizer 
    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

    Compiler 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: 

 9. References: 
    [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: Experiences NAIADE relatives a la propagation des neutrons dans
        l'eau legere diametre de la source 60 cm, rapport NEA/NSC/DOC(2006)24,
        Dec. 2006.
    [7] J.C. Nimal: NAIADE experiments relating to Fission Neutron Propagation in
        Light Water Source Diameter 60 cm, report NEA/NSC/DOC(2006)24, Dec. 2006.

 10. Data and Format: 

        Filename    Size[bytes] Content 
    --------------- ----------- ------------- 
 1 naiade-h2o.htm                         9.316 This information file  
 2 NSCDOC_2006_24 EN.pdf                208.534 Description of Experiment, Ref. [7]  
 3 NSCDOC_2006_24 FR.pdf                207.701 Description of Experiment, Ref. [6] (in French)  
 4 naiadeeau_60_fission_tripoli.data     57.048 TRIPOLI 4 input (direct flux)
 5 bruitdefond_eau_60_fission.data       58.399 TRIPOLI 4 input (background scattering)

SINBAD Benchmark Generation Date: 1/2007
SINBAD Benchmark Last Update: 1/2007