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SINBAD ABSTRACT NEA-1517/101

JANUS Phase I (Neutron Transport Through Mild and Stainless Steel)




 1. Name of Experiment:
    ------------------
    JANUS Phase 1 (1986)
 
 2. Purpose and Phenomena Tested:
    ----------------------------
    Neutron transport in regions of mild steel and stainless steel. The 
    purpose was to test the prediction of neutron penetration through 
    stainless steel when the incident spectrum was typical of that 
    emerging from a fast reactor.

 3. Description of the Source and Experimental Configuration:
    --------------------------------------------------------
    The source is a fission plate constructed of 93% enriched uranium aluminium
    alloy driven by a thermal flux from the extended graphite reflector of the 
    NESTOR reactor. The effective radius of the fission plate is 56 cm and the
    thickness 2 mm. The energy spectrum of the source is that of neutrons 
    emitted from the fission of U-235. The absolute source strength is 
    determined by fission product counting and the spatial distribution via 
    detailed low energy flux mapping with activation detectors.
    The fission plate is followed by steel plates which give 
    thicknesses of 17.85 cm mild steel, 40.39 cm stainless steel, and 
    56.72 cm mild steel. The initial region of mild steel modifies the 
    spectrum of neutrons incident upon the stainless steel to make it 
    closer to that leaving a fast reactor. The array has a 61 cm thick 
    biological shield of concrete behind this. 

 4. Measurement System and Uncertainties:
    ------------------------------------
    The activation detectors used were:

                                     Typical  Counting   Systematic
    Detector    Diameter   Thickness  Mass     System     Absolute
                 (mm)        (mm)      (g)               Calibration
                                                        (uncertainty)
  ----------------------------------------------------------------------
   Mn55(n,g)/Cd   12.7      0.15       0.12       NaI         1.5%

   Au197(n,g)/Cd  12.7      0.05     0.12-0.13    NaI         0.9%

   Rh103(n,n')    12.7      0.015      0.20       NaI         3.0%

   S32(n,p)       38.1      2.41        5        Plastic      5.0%
   Pressed Pellet                              Scintillator

   S32(n,p)       51        5.6        22        Plastic      5.0%
   Cast Pellet                                 Scintillator
  ----------------------------------------------------------------------

    The Mn and Au foils were contained in cadmium boxes of thickness 
    0.05 inches.

    In addition neutron spectrum measurements were made at three locations
    with three hydrogen proportional counters and an NE213 scintillator. 


 5. Description of Results and Analysis:
    -----------------------------------
    Measurements of the reaction rates for S32(n,p)P32, Rh103(n,n')Rh103m,
    Mn55(n,g)Mn56 Under Cd, and Au197(n,g)Au198 Under Cd were made at
    intervals of approximately 4.5cm through the stainless steel, and 5.1cm
    in the regions of mild steel. Lateral scans were made with sulphur, 
    rhodium, and gold at selected positions. 

    In addition, during all irradiations of activation detectors within the
    shields, three sulphur pellets were placed in locations at the centre of 
    the front face of the fission plate to monitor its run-to-run power via 
    the S32(n,p)P32 reaction. 
    
    The fast neutron spectra (E>52.5keV) were measured at three locations 
    within the region of stainless steel. The reaction rates for S(n,p) 
    and Rh(n,n') as derived from the spectra are compared with those 
    measured directly.

    The results were corrected for the background responses due to the NESTOR
    core. For the low energy detectors measurements were made with the plate 
    fuelled and unfuelled. For the threshold detectors the hydrogen 
    filled proportional counters of the TNS system were used in conjunction 
    with the boral shutter for Cave C at NESTOR. For the low energies the
    background varied from 19% close to the fission plate to 2% at deep
    penetrations. For the threshold detectors the corrections were small
    being typically 1% to 3%.

    Calculations were carried out with the Monte Carlo code McBEND Version 9B
    [4], [5]. 

    More recently the MCNP5 models were prepared [86] and are also incuded in
    this compilation.

 6. Quality Assessment:
    ------------------
    The JANUS-1 experiment is ranked as benchmark quality experiment. 
    The major drawback in the available experimental information is 
    represented by the specifications concerning the detectors arrangement.

 7. Author/Organizer
    ----------------
    Experiment and analysis:
    I.J. Curl, A K McCracken, P C Miller
    AEA Technology                        
    WINFRITH, Dorchester                  
    Dorset DT2 8DH                        
    UK 
   
    Compiler of data for Sinbad:
    A. Avery
    Performance and Safety Services Department, 
    AEA Technology
    WINFRITH, Dorchester                  
    Dorset DT2 8DH                        
    UK 

    Reviewer of compiled data:
    I. Kodeli
    OECD/NEA, 12 bd des Iles, 92130 Issy les Moulineaux, France

    Quality assessment:
    A. Milocco
    Universita' di Milano-Bicocca, piazza della Scienza 3, Milano, Italy

 8. Availability:
    ------------
    Unrestricted

 9. References:
    ----------
    [1] M. J. Armishaw, J. Butler, M. D. Carter, I. J. Curl, A. K. McCracken,
        "A Transportable Neutron Spectrometer (TNS) for Radiological 
        Applications", AEEW-M2365 (1986).
    [2] I. J. Curl,
        "CRISP - A Computer Code to Define Fission Plate Source Profiles", 
        RPD/IJC/934.
    [3] J. Butler et al. 
        "The PCA Replica Experiment, Part 1. Winfrith Measurements and 
        Calculations", AEEW-R1763
    [4] Wright G. A., Curl I. J., Hoare C. J., McCracken A. K., Miller P. C,
        and Ziver A. K., "Monte Carlo Sensitivity Analysis of Winfrith 
        Benchmark Experiment using JEF-1 Cross-Sections", Proceedings of the
        7th International Conference on Radiation Shielding, Bournemouth, p725,
        Sept. 1988.
    [5] Curl I. J., Calamand D., and Muller K. I., "The Role of the JANUS
        Experimental Shielding Programme in the Assessment of the Shielding
        Methods Employed for EFR", New Horizons in Radiation Protection and
        Shielding - ANS Topical Meeting, Pasco, p345, April 1992.
    [6] A. Avery, JANUS Phase 1 Benchmark Experiment Data for Inclusion in
        the SINBAD Database, Jan. 1998
    [7] A. Avery, A review of Shielding Benchmarks for the Validation of
        JEF 2.2, JEF/DOC-666, Nuclear Energy Agency, Paris, France, 1997.
    [8] A. Milocco, Quality Assessment of Evaluated Experiments
        NESDIP-2, NESDIP-3,JANUS-1 and JANUS-8, IJS-DP-11195, June 2012.

10. Data and Format:
    ---------------

    DETAILED FILE DESCRIPTIONS
    --------------------------
        Filename        Size[bytes]   Content
    ----------------    ----------- -------------
  1 jan1-abs.htm             11.065  This information file 
  2 jan1-exp.htm             34.633  Description of Experiment 
  3 MCBEND.inp              301.814  Input Data for McBEND M/C Code 
  4 FIG1.TIF                135.496  Figure 1: The ASPIS Mobile Shield Tank in the NESTOR Cave C 
  5 FIG2.TIF                178.240  Figure 2: Schematic Side Elevation of the Experimental Shield of 
                                     the JANUS Phase 1 in the ASPIS Trolley 
  6 FIG3.TIF                156.226  Figure 3: The Enriched U/Al Alloy Fission Plate 
  7 FIG4.TIF                203.604  Figure 4: Details of the Fuel Loading Pattern When Viewed Looking Towards 
                                     the NESTOR Cave 
  8 FIG5.TIF                153.738  Figure 5: The Individual U/Al Alloy Fuel Element 
  9 FIG6.TIF                176.778  Figure 6: The Fuel Element Configuration and Manganese Foil Positions 
 10 FIG7.TIF                117.838  Figure 7: Mesh Boundaries for the Fission Plate Source 
 11 FIG8.TIF                130.445  Figure 8: Location of Fission Discs in the Demountable Fuel Element 
 12 FIG9.TIF                287.269  Figure 9: Measurement Locations for JANUS Phase 1 
 13 FIG10.TIF               121.929  Figure 10: A Schematic for the Arrangement of the Spectrometer at 
                                     the Measurement Locations
 14 FIG1.gif                 19.324  Figure 1: The ASPIS Mobile Shield Tank in the NESTOR Cave C (preview) 
 15 FIG2.gif                 24.192  Figure 2: Schematic Side Elevation of the Experimental Shield of 
                                     the JANUS Phase 1 in the ASPIS Trolley (preview)
 16 FIG3.gif                 17.999  Figure 3: The Enriched U/Al Alloy Fission Plate (preview) 
 17 FIG4.gif                 20.477  Figure 4: Details of the Fuel Loading Pattern When Viewed Looking Towards 
                                     the NESTOR Cave (preview) 
 18 Fig5.gif                 16.245  Figure 5: The Individual U/Al Alloy Fuel Element (preview) 
 19 Fig6.gif                 23.546  Figure 6: The Fuel Element Configuration and Manganese Foil Positions (preview) 
 20 Fig7.gif                 12.619  Figure 7: Mesh Boundaries for the Fission Plate Source (preview) 
 21 Fig8.gif                 13.990  Figure 8: Location of Fission Discs in the Demountable Fuel Element (preview) 
 22 Fig9.gif                 28.184  Figure 9: Measurement Locations for JANUS Phase 1 (preview) 
 23 Fig10.gif                19.648  Figure 10: A Schematic for the Arrangement of the Spectrometer 
                                     at the Measurement Locations (preview) 
 24 janus1.pdf            2.172.714  Reference 
 25 jef-666.pdf             750.902  Reference 
 26 QualityAssessment.pdf   458.860  Document on JANUS-1 quality assessment
 27 J1Mn.i                   19.609  MCNPX(5) input model with the Mn activation foils 
 28 J1SRhAu.i                20.484  MCNPX(5) input model with the S, Rh, and Au activation foils 
 29 J1Sp.i                   18.529  MCNPX(5) input model with the whole set of spectrometers

    File JAN1-EXP.HTM contains the following tables: 
    One table (1) of axial dimensions and (2) of material specifications, two 
    tables (3 & 4) describing the source distribution, one table (5) of the 
    measured reaction rates, four tables (6-9) showing the lateral scans, 
    and three tables (10-12) giving the measured spectra. 

    Figures describing the geometry of the experiment are included in 
    TIFF5 compressed and GIF (preview) format .

SINBAD Benchmark Generation Date: 1997
SINBAD Benchmark Last Update: 1/2013