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SBE 10.002

IAEA Benchmark

1. Name of Experiment:

FNG Neutronics Bulk SS Shield Experiment (1995)

2. Purpose and Phenomena Tested:

The neutronics experiments were performed to validate the International Thermonuclear 
Experimental Reactor (ITER) inboard shielding design.    

3. Description of the Source and Experimental Configurations:

Using a 14-MeV-fusion-neutron source (deuterium atoms accelerated onto a tritium 
target) at the ENEA Frascati Neutron Generator Facility was used to perform 
measurements of neutron penetration of a 94-cm-thick mockup of the first-wall, 
blanket, vacuum vessel, and toroidal field coils.  The block was made of copper, 
stainless steel/Perspex (polyethelyne-type material, C5O2H8) sandwich, followed by a smaller 
block made of alternating plates of copper and stainless steel simulating the magnet.

4. Measurement Systems and Uncertainties:

Activation foils were placed along the center line of the experimental block in 
line with the source axis. Foils were placed at various depths along the axis, 
irradiated with the neutron source, and its activity recorded from calibrated HPGe
detectors.  Errors from counting statistics, uncertainty of detector calibrations, 
and the uncertainty of the source intensity are included with the reaction rate 
results.  Other errors are negligible.  

A set of TLD-300 detectors were used for measuring the nuclear heating as a 
function of depth inside the assembly.  These were calibrated by a 60Co 

The neutron source intensity was measured by the associated particle method, 
using a Silicon Surface Barrier Detector (SSD).  The accuracy of the measurement 
was +/- 2%.

5. Description of Results and Analysis:

The activation foils were place at 3.43, 10.32, 17.15, 23.95, 30.80, 41.85, 46.85, 
53.80, 60.55, 67.40, 74.40, 81.10, 87.75, and 92.15 cm from the front surface of 
the experimental block.  Results are given with the total, systematic, and random 
error (in %).  MCNP.4A was used to compute reaction rates for the foils.  

The absorbed dose measurements from the TLD-300 were taken at 3.36, 10.23, 17.09, 
23.95, 30.81, 41.88, 46.88, 53.89, 60.72, 67.58, 74.57, 81.20, 88.01, 95.36, 97.36,
99.76, 101.96 cm from the front surface of the experimental block.  Note that the 
measurements included the rear TF coil.  The measurements include systematic, 
random and total error (%), with accompanying MCNP calculations.  The absorbed 
dose in a material, Q, is given by the following equations:

Q = Qn+Qp
(QTLD) = CpQp+ CeCnQn
Q = QTLD + Qp[(1-CeCn)Qn/Qp+(1-Cp)] , where

QTLD is the response in the TLD, Qp and Qnis the 
gamma and neutron absorbed dose in the material, Cp is the ratio of 
photon dose in the TLD to the photon dose in the material, Cn is the 
ratio of neutron dose in the TLD to the neutron dose in the material.   Finally, 
Ce is the neutron sensitivity of the TLD-300 taken from the published 
literature [6].

The cell heating deposition tally (F6 N,P in MCNP) was used to calculate the 
neutron and gamma heating in stainless steel or copper during n,p coupled 
transport calculations.  The kerma factors for the photons and neutrons were 
taken from FENDL.1 and EFF-3 libraries.

6. Special Features:


7. Author/Organizer:

  Experiment and analysis:
P. Batistoni, M. Angelone, M. Pillon, L. Petrizzi, Associazione Euratom - 
ENEA sulla Fusione, C. R. Frascati - I- C. P. 65, 00044 Frascati, Italy
  Compiler of data for SINBAD:

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 

  Reviewer of compiled data:

P. Batistoni, ENEA Fusion Division Via E. Fermi 27, I-00044 Frascati 
(Roma), ITALY

8. Availability:


9. References:

[1]    M. Martone, M. Angelone, M. Pillon, "The 14-MeV Frascati Neutron Generator 
(FNG)", ENEA Report RT/ERG/FUS/93/65 
[2]    M. Angelone, M. Pillon, P. Batistoni, M. Martini, M. Martone, V. Rado, 
" Absolute experimental and numerical calibration of the 14 MeV neutron 
source at the Frascati Neutron Generator,  Rev. Sci. Instrum. 67(6)(1996)2189
[3]    P. Batistoni, M. Angelone, W. Daenner, U. Fischer, L. Petrizzi, M. Pillon, 
A. santamarina, K. Seidel, "Neutronics Shield Experiment for ITER at the 
Frascati Neutron Generator FNG", 17th Symposium on Fusion 
Technology, Lisboa, Portugal, September 16-20, 1996.
[4]    J. H. Baard, W. L. Zijp, H. Nolthenius, "Nuclear Data Guide for Reactor 
Neutron Metrology",  Kluwer  Academic Publishers for the Commission of the 
European Community, (1989).
[5]    M. Angelone, C. Arpesella, M. Martone, M. Pillon, " Activation 
measurements for the E.C. bulck shield benchmark experiment, Proc. of the 4-th 
Int. Conf. on Application of Nuclear Techniques, Crete (Greece) June 1994, SPIE 
Publ. vol. 2339 pp. 220-224
[6]    M. Angelone, P. Batistoni. A. Esposito, M. Pillon, V. Rado, " Gamma 
and neutron dosimetry using CaF2:Tm thermoluminescent dosimeters for fusion 
reactor shielding experiments ", Nucl. Sci. Eng. 126, p 176 June (1997).
[7]    L. Petrizzi, V. Rado, M. Angelone, P. Batistoni, M. Martone, M. Pillon, 
" Analysis of nuclear heating experiments for the ITER shielding blanket, 
Proc. of  a Specialist Meeting on Measurement, Calculation and Evaluation of 
Photon Production  Data, Bologna, Italy Nov. 9-11, 1994, Edited by: C. Coceva, 
A. Mengoni, A. Ventura, NEA/NSC/DOC(95)1

10. Data and Format:


(1) Source neutron spectrum averaged over spherical cap of 60 degree aperture.
(2) Source FORTRAN file used by MCNP.4 to calculate 14-MeV neutron source.
(3) GEOM.DAT - Geometry input file used by MCNP.
(4) DETEC.DAT - List of activation reactions, foil locations, and foil size
(5) RREXP.DAT - Experimental data for reaction rate measurements.
(6) RRCALC.DAT - Calculated reaction rates using FENDL-1 library and MCNP 
(7) NHEXP.DAT - Expermental dose measurements for nuclear heating.
(8) NHCALC.DAT - Calculated nuclear heating using MCNP/FENDL-1/EFF-3.


Fig. 1 - The bulk shield mock-up configuration
Fig. 2 - The bulk shield mock-up assembly in front of  FNG target, without the 
Polyethylene shield.
Fig. 3 - The bulk shield mock-up assembly in front of  FNG target, with the 
Polyethylene shield.
Fig. 4 - The mock-up in position on the movable tower at the centre of the FNG 
bunker, at  4 m from the floor, at a distance of  5.3 cm from the neutron source.

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Abstract Generation Date: 06/98

Abstract Last Update: 09/98