Neutron spectrometry measurements in iron

Directorate-General For Translation European Commission

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Nuclear energy and safety

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• Publié par: EUROPEAN-COMMISSION
• Nombre de lectures: 48
• Langue: Vietnamese
• Poids de l'ouvrage: 1 Mo

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euri /i-y^
Commission of the European Communities
nuclear science and technology
NEUTRON SPECTROMETRY
MEASUREMENTS IN IRON
Report
EUR 11767 EN
Blow-up from microfiche original Commission of the European Communities
nuclear science and technology
NEUTRON SPECTROMETRY
MEASUREMENTS IN IRON
G. PERLINI*. M. CARTER**, S. ACERBIS*
* Commission of the European Communities
Joint Research Centre
Ispra Establishment
1-21020 Ispra (VA)
" UKAEA, AEE Winfrith (UK)
M
PAR
Directorate-General Science, Research and Development
:.c Joint Research Centre
r
1988 |ClfţlR 117R7 FN Published by the
COMMISSION OF THE EUROPEAN COMMUNITIES
Directorate-General
Telecommunications, Information Industries and Innovation
Bâtiment Jean Monnet
LUXEMBOURG
LEGAL NOTICE
Neither the Commission of the European Communities nor any person acting on behalf
of then is responsible for the use which might be made of the following
information
ECSC—EEC—EAEC Brussels - Luxembourg. 1988 III
CONTENTS
Page
SUMMARY V
1. Introduction 1
2. The model for the study of neutron penetration in iron 1
3. Spectrum measurement method 3
4. Neutron spectra measured in iron 11
5. Appendix (Table of the spectra of the impulses collected
and of the neutron spectra for the various positions) 33 SUMMARY
A compact structure was prepared for use in making measurements of
neutron penetration in iron which could serve as reference data
and as a check for computer codes. About 30 iron plates were put
together giving a useful overall length of 130 cm. At various depths
along the central axis of the iron block, measurements were made
with liquid scintillator spectrometers and proton recoil proportional
counters.
The energy band explored was between 14 keV and 10 MeV;
Here we report the original spectra of the impulses and the neutron
spectra found by the NE213 code based on the differential method
and by unfolding with the SPEC4 code for liquid scintillation coun­
ters and proton recoil spectrometers, respectively. 1. INTRODUCTION
Iron is one of the materials most commonly used in reactor structures
and shields.
An experiment was designed to test the calculation methods and cross
sections used to study deep penetrations in iron: it had a simple
geometry and a source spectrum which was sufficiently known so that
it could be simulated with modern calculation methods without too
many simplifications.
The neutron source used was that which originated from the fissions
in an enriched uranium disc 80 cm in diameter subjected to the neutron
flux leaving the thermal column of the TRIGA MARK II reactor of the
University of Pavia.
An irradiation cell with borated barytic concrete walls was con­
structed in front of the convertor. The resulting internal cavity
which could be used for the experiments had an internal transverse
section of about 150 x 150 cm.
The EURACOS II installation is described in the Technical Note /l/
(Fig. 1).
A first series of measurements of the neutron flux of the source in
an empty chamber was compared with the calculation performed with
the TIMOC Monte Carlo code /2/. This allowed us to determine the
intensity of the source with the reactor at maximum power (Is *
6.12 x 10 exp 11 n/sec) and the cosinusoidal geometric distribution
of emission S(a) = a*cos(ar) where a = 0.0292.
2. THE MODEL FOR THE STUDY OF PENETRATION IN IRON
The measurements were performed in an iron block with overall dimen­
sions 145 x 145 x 130 cm. This block was obtained by assembling
about thirty iron plates (145 x 145 x 4 cm) which had previously been
worked so that their surfaces were as plane as possible so that
they could be placed very closely together, thus avoiding air inter­
stices. M
Fig. 1 - EURACOS installation with iron assembly inside the irradiation tunnel.