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SBE 1.001

1. Name of Experiment

Measurements of the JASPER program Radial Shield Attenuation Experiment (1986)

2. Purpose and Phenomena Tested

The radial shield attenuation experiment was designed to investigate neutron transmission 
through benchmark and representative mockups of radial shield designs for advanced 
sodium-cooled reactors.

3. Description of the Source and Experimental Configuration

The neutron source was the Tower Shielding Reactor II (TSR-II) located at the Tower 
Shielding Facility at Oak Ridge National Laboratory. The emergent source spectrum was 
modified to be similar to that predicted for the LMR (liquid metal reactor) design 
using one of two different modifiers.  One modifier approximated the energy distribution 
for a near core shield while the other was designed to resemble the flux near the 
intermediate heat exchanger (IHX).

The components used in the experimental mockups were slabs of stainless steel, graphite,
boron carbide, boral, and sodium.  All slabs were 1.5m on a side with varying thicknesses.
The near-core spectrum modifier of iron, aluminum, boral and a "radial blanket" of natural 
UO2 was placed in the beam.  For the IHX modifier, the "radial blanket" was replaced with
183cm of sodium.

4. Measurement System and Uncertainties

Three different types of detection systems were used for this experiment.  A set 
of Bonner balls filled with BF3 gas was used to measure neutron flux.  To cover 
a range of neutron energies, the counter is used bare, covered with cadmium, or 
enclosed in various thicknesses of polyethylene shells surrounded by cadmium.  
An NE-213 liquid scintillator measured the spectrum from 800 keV to 50 MeV.  
Spherical proton-recoil counters , filled with hydrogen to pressures of 1, 3, 
and 10 atmospheres, covered the neutron energy range from about 50 keV to 1 MeV.  
A study of sodium activation was made using sodium carbonate filled polystyrene 
capsules measured utilizing a well-shielded Ge(Li) detector.

The uncertainty in the reactor power determination was assumed to be +/- 5%. The 
NE-213 and hydrogen counter measurements were expressed in terms of lower and 
upper limits that represented a 68% confidence interval. Both of the spectra for 
these counters has an error of about +/- 5%.  The errors assigned to the Bonner 
ball measurements should lie within about +/- 10%.

5. Description of Results and Analysis

Six different measurements of the neutron spectra were taken: (1) near core shield, 
(2) benchmark experiment, (3) tank type radial shield, (4) IHX shield, (5) graphite 
benchmark, and (6) near core shield.

Data from the Bonner ball measurements was predicted analytically by folding a 
calculated neutron spectrum with the Bonner ball response functions.  The NE-213 
pulse-height data was unfolded suing the FERD code to yield absolute neutron 
energy spectra.  Pulse-height data from the spherical proton-recoil counters was 
unfolded using the SPEC-4 code.

The measurements for each detector were referenced to the reactor power (watts) 
using the data from two fission chambers positioned along the reactor centerline 
as a basis.

6. Special Features

This report has recently been released by the U.S. Department of Energy.

7. Author/Organizer

Experiment and Analysis:
	F.J. Muckenthaler*, B.D. Rooney*, J.D. Drischler*, N. Ohtani**,
	J.L. Hull*, L.B. Holland*
	* Oak Ridge National Laboratory
	** Japan Power Reactor and Nuclear Fuel Development Corporation

Compiler of data for SINBAD:
        William Marshall, RSICC, Oak Ridge National Laboratory, P.O. Box 2008, Oak 
        Ridge, TN 37831-6362

Reviewer of compiled data:
        Hamilton Hunter, RSICC, Oak Ridge National Laboratory, P.O. Box 2008, Oak 
        Ridge, TN 37831-6362, fax 423-574-6182, e-mail h3o@ornl.gov

8. Availability


9. References

[1] R.E. Maerker et al., "Calibration of the Bonner Ball Neutron Detectors Used at the Tower 
Shielding Facility," ORNL/TM-3465 (June 1971).
[2] C.E. Burgart and M.B. Emmett, "Monte Carlo Calculations of the Response 
Functions of Bonner Ball Neutron Detectors," ORNL/TM-3739 (April 1972).
[3] B.W. Rust, D.T. Ingersoll, and W.R. Burrus, "A User’s Manual for the FERDO and FERD 
Unfolding Codes," ORNL/TM-8720 (September 1983).
[4] J.O. Johnson and D.T. Ingersoll, "User’s Guide for the Revised SPEC-4 Neutron 
Spectrum Unfolding Code," ORNL/TM-7384 (August 1980).
[5] W.W. Engle, Jr., D.T. Ingersoll, C.O. Slater, F.J. Muchenthaler, "Specifications 
for the JASPER Program Attenuation Experiment," ORNL/LMR/AC-86/5 (October 1986).

10. Data amd Format:

	(1)-(11)  Composition and analysis tables of different matierials
	(12)-(13) Neutron fluxes
	(14)-(17) Bonner ball measurements
	(18)-(19) Neutron fluxes
	(20)      Bonner ball measurements
	(21)-(22) Neutron fluxes
	(23)-(27) Bonner ball measurements
	(28)-(29) Neutron fluxes
	(30)-(31) Bonner ball measurements
	(32)-(33) Neutron fluxes

	(1) Spectrum modifier 1
	(2) Radial blanket
	(3) Spectrum modifier 2
	(4) Stainless stell slabs for boron carbide
	(5)-(24) Schematics of various experimental configurations

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SINBAD Abstract Generation Date: 6/99

SINBAD Abstract Last Update: 10/99