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SBE 1.014

1. Name of Experiment:

SDT12. A Benchmark Experiment for Neutron Transport in Thick Sodium - 1974

2. Purpose and Phenomena Tested:

This experiment was designed to verify the accuracy of sodium cross sections to be 
used in transport calculations.

3. Description of the Source and Experimental Configuration:
The source used was a collimated beam of reactor neutrons from the Tower Shielding 
Reactor at the Tower Shielding Facility located in Oak Ridge National Laboratory. 
Measurements of neutron fluence and neutron spectra were made behind various 
combinations of four 11-ft-diameter cylindrical aluminum tanks filled with solid 
sodium up to 15-ft-thick. Concrete, at least 1.5-ft-thick, surrounded the periphery 
of the tanks to reduce the effects of transverse leakage from the slabs.

The average thickness of the four sodium tanks, including 1 inch of aluminum, was 
29.91 +/- 0.22, 60.08 +/- 0.52, 59.86 +/- 0.42, and 29.56 +/- 0.53 inches for tanks 
1, 2, 3, 4 respectively. The density of the sodium tanks averaged 0.945 g/cm3, 
which is accurate to 1%.

4. Measurement System and Uncertainties:

The spectral measurements were taken using two types of spectrometers: (1) a NE-213 
scintillator, and (2) a Benjamin proton recoil spectrometer. The NE-213 was used to 
determine the spectra in the energy range of 0.8 to 15 MeV. The Benjamin 
spectrometer was used to determine the spectra in the range of ~70 keV to 1.5 MeV. 
In addition, a set of spherical BF3 detectors ("Bonner balls") were used to obtain 
integral flux measurements.

The accuracy of the incident absolute source spectrum is estimated to be +/- 10%
down to 200 keV and +/- 20% below 200 keV. All the measurements have an estimated 
reproducibility of +/- 5%, due primarily to power calibration uncertainties. 

5. Description of Results and Analysis:

Measurements were obtained behind sodium thicknesses of 2.5, 5, 10, 12.5, and 15
feet and covered an energy range of ~70 keV to 11 MeV. Measurements of the incident 
neutron beam were made with each detector to obtain an absolute energy spectrum.

The spectra measurements obtained from the NE-213 were unfolded by the FERDoR 
computer code. The spectra measurements obtained from the Benjamin spectrometer were
unfolded by the SPEC4 computer code. Spectral errors in the data unfolding 
statistics are shown by one sigma percentage values for the Benjamin counters and 
high/low values for the NE-213. The results were obtained using multigroup Monte 
Carlo, MORSE, and two-dimensional discrete ordinates code, DOT-III.

6. Special Features:

The NE-213 energy resolution and the Bonner ball response functions are included to 
aid in computational comparison with results.

7. Author/Organizer:

Experiment and Analysis:
    R. E. Maerker and F. J. Muckenthaler, ORNL-4480

Compiler of data for SINBAD:
    Jennifer Parsons, Radiation Shielding Information Center, Oak Ridge National 
    Laboratory, P.O. Box 2008, Oak Ridge, TN 37831-6362

Reviewer of compiled data:
    Hamilton Hunter, Radiation Shielding Information Center, Oak Ridge National 
    Laboratory, P.O. Box 2008, Oak Ridge, TN 37831-6362, fax 423-574-6182, e-mail 

8. Availability:


9. References:

[1] R.E. Maerker, F.J. Muckenthaler, R.L. Childs, M.L. Gritzner, "Final Report on a 
    Benchmark Experiment for Neutron Transport in Thick Sodium," ORNL-4880, Oak 
    Ridge National Laboratory (January 1974).
[2] R.E. Maerker, F.J. Muckenthaler, J.J. Manning, J.L. Hull, J.N. Money, K.M. 
    Henry, Jr., and R.M. Freestone, Jr., "Calibration of the Bonner Ball Neutron 
    Detectors Used at the Tower Shielding Facility," ORNL-TM-3465, Oak Ridge 
    National Laboratory (1971).
[3] G.L. Simmons, Editor, "Shielding Benchmark Problems," ORNL-RSIC-25 (ANS-SD-9),
    Oak Ridge National Laboratory (1974).
[4] F.J. Muckenthaler, R.R. Spencer, H.T. Hunter, J.L. Hull, and A. Shono, 
    "Measurements for the Jasper Intermediate Heat Exchanger Experiment," 
    ORNL-TM-12064 (July 1992).

10. Data and Format:

    (1) Source spectrum at the end of the collimator
    (2) NE-213 resolution function
    (3) Bonner ball description
    (4) Bonner ball response functions
    (5) Experimental configurations
    (6)-(8) NE-213 spectrum
    (9)-(13) Benjamin counter spectrum
   (14)-(22) Bonner ball counting rates

    (1) Side-view of reactor and sodium shield geometry

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SINBAD Abstract Generation Date: 06/98

SINBAD Abstract Last Update: 06/98