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Winfrith Iron 88 Benchmark (ASPIS)

 1. Name of Experiment:
    Winfrith Iron 88 Benchmark Experiment (ASPIS)

 2. Purpose and Phenomena Tested:
    Determination of the neutron transport for penetrations up to 67 cm in 

 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 shield is made from 13 mild steel plates, each approximately 5.1 cm
    thick, with a gap of average thickness of 7.4 mm between them, to allow
    detector access within the shield. Each plate is 1.8 m x 1.9 m in
    cross-section. Behind this array is a deep backing shield manufactured 
    from mild and stainless steel, respectively 20.32 cm and 22.41 cm thick. 
    The outer boundaries of the experimental region are formed by the walls
    and floor (steel plates) of the ASPIS trolley and by the roof of the 
    ASPIS cave. Concrete encases the whole assembly.

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

                                     Typical  Cadmium    Counting   Systematic
    Detector    Diameter   Thickness  Mass     Cover      System     Absolute
                 (mm)        (mm)      (g)    (inches)             Calibration
  Au197(n,gamma) 12.7        0.05   0.12-0.13  50/1000     NaI        0.9%

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

  In115(n,n')     38         1.63    12.79       -        GeLi        1.9%

  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

  Al27(n,alpha)   50         3.1     16.72       -      Ge detector   2.2%  

 5. Description of Results and Analysis:

    Detector activation measurements were carried out along the fission
    plate axis at the following shield thicknesses: 0, 5.1, 10.22, 15.34, 
    20.44, 25.64, 30.79, 35.99, 41.19, 46.44, 51.62, 56.69, 61.81, 66.99 cm. 
    Al27 reaction rates were measured only up to 25.64 cm.
    Lateral distributions were also measured at various positions in the 
    shields, the foils being located at intervals of 25 cm up and down from
    the nuclear centre line. 

    The results were corrected for the background responses due to the NESTOR
    core. Using the hydrogen filled proportional counters the correction was 
    found to be around 2% throughout the shield for the four threshold 
    detectors. For gold measurements the measurement was repeated with the 
    fissile content of the fission plate removed in order to determine the 
    background correction.

    Calculations were carried out with the Monte Carlo code McBEND version 7B.
    The corresponding input is included.

 6. Special Features:


 7. Author/Organizer
    Experiment and analysis:
    S. Bell, I.J. Curl, G.A. Wright:
    AEA Technology                        
    WINFRITH, Dorchester                  
    Dorset DT2 8DH                        
    Compiler of data for Sinbad:
    I. Kodeli
    OECD/NEA, 12 bd des Iles, 92130 Issy les Moulineaux, France

    Reviewer of compiled data:
    Alan F. Avery
    Reactor Physics, Shielding and Criticality Department, AEA Technology
    WINFRITH, Dorchester
    Dorset DT2 8DH

 8. Availability:


 9. References:

    [1] G.A. Wright, M. J. Grimstone,
        Benchmark Testing of JEF-2.2 Data for Shielding Applications: Analysis
        of the Winfrith Iron 88 Benchmark Experiment, Report No. AEA-RS-1231,
        EFF-Doc-229 and JEF-Doc-421 (1993).
    [2] I. J. Curl,
        CRISP - A Computer Code to Define Fission Plate Source Profiles, 
    [3] 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).
    [4] G. A. Wright, A. Avery, M. J. Grimstone, H. F. Locke, S. Newbon,
        Benchmarking of the JEFF2.2 Data Library for Shielding Applications,
        Proceedings, 8th International Conference on Radiation Shielding, 
        April 24-28, 1994, Arlington, Texas, U.S.A., vol.2, p.816.

10. Data and Format:


        Filename     Size[bytes]   Content
    ---------------- ----------- -------------
  1 as88-abs.htm          8.645  This information file 
  2 as88-exp.htm         25.009  Description of Experiment 
  3 MCBEND.INP           14.967  Input for McBEND MC Code (contributed by Dr. Chucas, Winfrith). 
  4 Fe88-1v.tif          62.008  Figure 1: Schematic Side Elevation of the ASPIS Shield (high quality) 
  5 Fe88-2v.tif          92.550  Figure 2: Measurement Locations (high quality) 
  6 Fe88-3v.tif          65.934  Figure 3: The Enriched U/Al Alloy Fission Plate (high quality) 
  7 Fe88-4v.tif          13.714  Figure 4: U/Al Alloy Fuel Element (high quality) 
  8 Fe88-5v.tif          76.474  Figure 5: Details of the Fuel Loading Pattern when Viewed 
                                           Looking Towards the NESTOR Cave (high quality) 
  9 Fe88-6.tif          648.635  Figure 6: Fission Plate Positioning (high quality) 
 10 Fe88-1v.gif          22.383  Figure 1: Schematic Side Elevation of the ASPIS Shield (preview) 
 11 Fe88-2v.gif          30.363  Figure 2: Measurement Locations (preview) 
 12 Fe88-3v.gif          19.360  Figure 3: The Enriched U/Al Alloy Fission Plate (preview) 
 13 Fe88-4v.gif           6.976  Figure 4: U/Al Alloy Fuel Element (preview) 
 14 Fe88-5v.gif          24.229  Figure 5: Details of the Fuel Loading Pattern when Viewed 
                                           Looking Towards the NESTOR Cave (preview) 
 15 Fe88-6.gif           20.935  Figure 6: Fission Plate Positioning (preview) 
 16 IRON_88.pdf       2.195.113  Reference 
 17 jef-476.pdf         578.980  Reference 
    File AS88-exp.htm contains the following tables:
    One table of axial dimensions and of chemical composition of materials
    present in the configuration, one table describing the source distribution, 
    and 5 tables of the measured reaction rates.