1. Name of Experiment:
 ------------------
 Ispra Sodium Benchmark Experiment (EURACOS) (~1986)


2. Purpose and Phenomena Tested:
 ----------------------------
 Study of the neutron deep penetration in homogeneous materials commonly used
 in the construction of advanced reactors: Na (and Fe). Flux and spectra were
 measured up to 360 cm in Na.

3. Description of the Source and Experimental Configuration:
 --------------------------------------------------------
 The neutron source in a converter disc made of 6 trapezoidal U-Al alloy
 plates forming an almost circular source with a diameter of 80 cm. The space
 dependence of the source can be approximated by a cosinusoidal radial
 profile. The spectrum is very similar to the U235 fission spectrum.
 The converter is situated at the end of the thermal column of a TRIGA MARK II
 reactor (University of Pavia) in front of the irradiation chamber which is
 surrounded by borated concrete walls of two different compositions.
 The first part extending from 35 cm to 162.4 cm from the converter mid-plane
 (see Fig. 1) consists of ordinary concrete with a density of 2.3 g/cm3. The
 second part of the tunnel shield is made of heavy concrete with a density of
 3.6 g/cm3. Its composition is listed in Table 3.
 The Na mock-up was made of 7 Fe containers filled with liquid Na, having a
 useful length of 382 cm. A Boral plate was placed between the source and the
 Na block to reduce the low energy flux originating in the thermal column.
 Use of large sulphur detectors, and low background measurements during a
 counting period of 5-6 half lives, made it possible to measure attenuation
 up to 7 decades of fast neutrons.

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

 Detector                       Diameter   Thickness   Error
                                 (cm)        (cm)      (%)
 ----------------------------------------------------------------
 S-32(n,p)P-32/under Cd          2 - 7     0.2 - 10   5.6 - 15.5
 Au-197(n,gamma)Au-198/under Cd   1.0        0.01      5 - 8
 H proportional counters          4.04 (spherical)
 ----------------------------------------------------------------
 The gold foil consists of an Au/Al alloy with 0.1 wt% gold content.
 The thickness of the Cd-coating is 1 mm (S-32 and Au-197).
 The energy resolution of the proton recoil spectrometers is between 5 and 15%.


5. Description of Results and Analysis:
 -----------------------------------

 Measurements with activation detectors were carried out at distances
 18.35, 66.4, 125.2,184.5, 243.2, 302.4, 362.2 cm for S-32(n,p) and
 Au-197(n,gamma). The radial profiles were measured with Ni-58(n,p) at 62 cm
 depth in Na, and with Au-197(n,gamma) at 95.4, 121 and 213.5 cm in Na.
 Energy range between 100 and 650 keV was covered with hydrogen proportional
 counters. The spectra were unfolded by the SPEC4 code [9], and normalized
 with the BF3 monitor. The neutron spectra are given at 6 positions in Na
 (18.35, 66.4, 125.2, 184.5, 243.2, 302.4 cm).
 As the authors are not completely confident that the unfolding was performed
 according to state-of-the-art procedures, the original distributions of the
 impulses measured by spectrometers and the detector geometry are included as
 well for those who wish to carry out their own unfolding.
 MCNP calculations performed using various flux estimators are described in
 [6]. An input file for the MCNP-3 code is available in mcnp3-na.inp. See the 
 EURACOS Iron benchmark compilation eufe-abs.htm for hints on how to prepare
 an input for MCNP-4c from the MCNP-3 file.

6. Special Features:
 ----------------

 None

7. Author/Organizer
 ----------------
 Experiment and analysis:
 R. Nicks, G. Perlini, H. Rief,
 Joint Research Centre, Ispra, 21020 Ispra (Varese), Italy

 Compiler of data for Sinbad:
 I. Kodeli
 OCDE/NEA, 12 bd des Iles, 92130 Issy les Moulineaux, France

 Reviewer of compiled data:
 H. Rief
 Joint Research Centre, Ispra, 21020 Ispra, Italy

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

 Unrestricted

9. References:
 ----------

 [1] Nicks R., Perlini G. and Rief H., Project and performances of the EURACOS II
 irradiation facility. Technical Note No. 1.05.00.85.45, JRC Ispra. (1985)
 [2] Nicks R., Perlini G., Rief H., Fission neutron penetration in iron and
 sodium-I. Activation measurements. Ann. Nucl. Energy 15, p.457 (1988)
 [3] Perlini G., Rief H., Fission neutron penetration in iron and sodium-II.
 Neutron spectrometry. Ann. Nucl. Energy 16, p.189 (1988)
 [4] R. Nicks et al., "Iron and sodium benchmark experiments at EURACOS II-
 Part I: Activation measurements", NEACRP Specialists' Meeting on Shielding
 Benchmark, Paris, October 13-14, 1986.
 [5] G. Perlini, H. Rief, M.D. Carter, N.F. Murphy, The S32(n,p)P32 threshold
 detector and its application for fast neutron dosimetry (fast reactors and
 fusion reactors), Reactor Dosimetry, ECSC, ECC and EAEC, Brussels and
 Luxembourg, p.457 (1985).
 [6] H. Rief, Shamsi T. A., Aglietti-Zanon M. and Vittone E., EURACOS 10.
 Team EN.102/017 (1987).
 [7] R. Garofoli, G. Gonano, G. Perlini, H. Rief, Fast neutron attenuation in
 large iron and sodium columns, 9th European Triga Conference, C.R.E.,
 Casaccia, Roma, (1986).
 [8] G. Perlini and S. Acerbis, Neutron spectrometry measurements in sodium.
 Report EUR 11095 EN, Ispra. (1987)
 [9] P.W. Benjamin, The analysis of recoil proton spectra, AWRE 09/68,
 Aldermaston, Berks (1968).
 [10] G. Perlini, S. Acerbis, U. Canali, G. Gonano, R. Nicks, H. Rief,
 Construction of a neutron deep penetration sodium shield mockup,
 European Appl. Res. Rept.- Nucl. Sci. Technol., Vol. 7, No.6 (1987).


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

 DETAILED FILE DESCRIPTIONS
 --------------------------
 Filename            Size[bytes] Content
 ---------------- ----------- -------------
  1 euna-abs.htm         11.125  This information file 
  2 euna-exp.htm         19.313  Description of Experiment 
  3 EURNA.TB1            28.484  Tables of Neutron Spectra 
  4 EURNA.TB2            50.812  Tables of Measured Impulses 
  5 mcnp3-na.inp         16.090  Input Data for MCNP Version 3 Code 
  6 EURNA-1V.TIF         26.832  Figure 1: Cross-section of the EURACOS2 facility (high quality)  
  7 EURNA-2V.TIF         79.002  Figure 2: Schematics of the experimental configuration (high quality) 
  8 EURNA-3V.TIF         13.118  Figure 3: U235 neutron converter (high quality)  
  9 EURNA-4V.TIF         15.970  Figure 4: Activation detector support (high quality)  
 10 EURNA-5V.TIF          9.680  Figure 5: Positioning of gas spectrometer (high quality)  
 11 EURNA-6V.TIF         18.702  Figure 6: Cross-section of the sodium containers with detectors (high quality)
 12 EURNA-7V.TIF         17.934  Figure 7: Sulphur detector support device (high quality)  
 13 eurna-8.jpg         227.694  Figure 8: 3D view of the EURACOS2 sodium experiment 
 14 Eurna-1v.gif         11.417  Figure 1: Cross-section of the EURACOS2 facility (preview) 
 15 Eurna-2v.gif         28.009  Figure 2: Schematics of the experimental configuration (preview)  
 16 Eurna-3v.gif         13.767  Figure 3: U235 neutron converter (preview)  
 17 Eurna-4v.gif         11.975  Figure 4: Activation detector support (preview)  
 18 Eurna-5v.gif          9.257  Figure 5: Positioning of gas spectrometer (preview)  
 19 Eurna-6v.gif          8.771  Figure 6: Cross-section of the sodium containers with detectors (preview)
 20 Eurna-7v.gif         10.977  Figure 7: Sulphur detector support device (preview)  
 21 Eur_01.pdf        1.139.611  Reference  
 22 Eur_02.pdf          537.382  Reference 
 23 Eur_03.pdf          503.082  Reference 
 24 Eur_04.pdf          655.408  Reference 
 25 Eur_05.pdf          185.260  Reference 
 26 Eur_06.pdf        3,944.371  Reference 
 27 Eur_07.pdf          384.022  Reference 
 28 EUR_NA_8.pdf      1.505.251  Reference 
 29 EUR_10.pdf          599.783  Reference 
 30 EUR_11.pdf          208.011  Reference 
 31 EUR_13.pdf          404.659  Reference 
 32 EUR_14.pdf          313.815  Reference 
 33 EUR_15.pdf          397.685  Reference 
 34 EUR_16.pdf          823.089  Reference 
 35 EUR_17.pdf          432.065  Reference 
 36 EUR_18.pdf          638.823  Reference 
 37 EUR_19.pdf          440.870  Reference 
 38 EUR_20.pdf          318.053  Reference 

 Files EUNA-EXP.HTM, EURNA.TB1, EURNA.TB2 contain the following tables:
 5 tables of chemical compositions of materials present
 9 tables of measured reaction rates
 1 table presenting neutron spectra measurements conditions
 9 tables of spectra derived from measurements using SPEC 4 unfolding code
 9 tables of measured impulses used for unfolding an input example for SPEC 4
 code.
 
    Figures are included in GIF, JPG and TIF formats.

SINBAD Benchmark Generation Date: 07/1995
SINBAD Benchmark Last Update: 3/2006