Nondestructive Activation Analysis: With Nuclear Reactors and Radioactive Neutron Sources

370 Pages·1981·41.081 MB·English

by  SAADIA AMIEL (Eds.)

STUDIES IN ANALYTICAL CHEMISTRY 3
Editorial Board
E. Pungor (Budapest), W. Simon (Zurich),
J. Inczedy (Veszprem)
Volume 1 Structural Analysis of Organic Compounds by Combined Application of
Spectroscopic Methods (Clerc, Pretsch, Seibel)
Volume 2 Tht Principles of Ion-Selective Electrodes and of Membrane Transport
(Morf)
Volume 3 Nondestructive Activation Analysis (Amiel, editor)
PUBLISHER'S NOTE
It was with deep regret that we learnt of the untimely death of Professor
Saadia Amiel in 1978. At the time, he was in the process of editing the manu-
scripts he had received for this book. We are most grateful to his colleague,
Dr Mariana Mantel, at the same address, who was prepared to complete
the editorial work.
STUDIES IN ANALYTICAL CHEMISTRY 3
Nondestructive
Activation
Analysis
With Nuclear Reactors and Radioactive Neutron Sources
Edited by
SAADIA AMIEL
Nuclear Chemistry Department, Israel Atomic Energy Commission,
Soreq Nuclear Research Center, Yavne 70600, Israel
ELSEVIER SCIENTIFIC PUBLISHING COMPANY
Amsterdam — Oxford - New York 1981
ELSEVIER SCIENTIFIC PUBLISHING COMPANY
335 Jan van Galenstraat
P.O. Box 211, 1000 AE Amsterdam, The Netherlands
Distributors for the United States and Canada:
ELSEVIER/NORTH-HOLLAND INC.
52, Vanderbilt Avenue
New York, N.Y., 10017
Library of Congress Cataloging in Publication Data
Main entry under title:
Nondestructive activation analysis.
(Studies in analytical chemistry ; 3)
Includes bibliographical references and index,
1. Radioactivation analysis. I. Amiel, Saadia.
II Series
QD606.N66 * 5hy.0882 80-27^56
ISBN 0-Kkk-kl3h2-X
ISBN 044441942-X (Vol. 3)
ISBN 0444-41944-6 (Series)
© Elsevier Scientific Publishing Company, 1981
All rights reserved. No part of this publication may be reproduced, stored in a retrieval system or
transmitted in any form or by any means, electronic, mechanical, photocopying, recording or other-
wise, without the prior written permission of the publisher, Elsevier Scientific Publishing Company,
P.O. Box 330,1000 AH Amsterdam, The Netherlands.
Printed in The Netherlands
Professor Saadia Amiel
1928-1978
FOREWORD
The idea of editing a book dealing exclusively with non destructive activation anal-
ysis originated with the late Professor Saadia Amiel. With his distinctive style in scien-
tific research, he strived to solve problems in the simplest way and with the greatest
economy of effort. He was a strong believer in the potential of nondestructive tech-
niques in general, and of nondestructive activation analysis in particular. Therefore,
during all the years of his scientific activity he pursued the development of this tech-
nique and pioneered its application to a large variety of analytical problems. The large
number of papers that he published on the subject constitute a proof of his interest
and achievement in this field.
Professor Amiel was aware of the great number of books that had been published
about neutron activation analysis. In his opinion, however, none of these works suf-
ficiently emphasized the merits and possibilities of the technique of nondestructive
activation analysis. He wanted to draw the attention of his fellow scientists to the po-
tential of this technique and at the same time to show them how it had been applied
before and how it could be used in the future in different fields of science. For these
reasons, he decided to edit this book in which the technique of nondestructive anal-
ysis is explained in detail and its advantages and shortcomings are pointed out. He also
hoped that the book would serve as a guide to the use of this technique which he so
strongly recommended.
Unfortunately, Saadia's prolific scientific career was brought to a sudden halt by
premature death caused by brain cancer. This unyielding and terrible disease struck
when he had nearly finished editing this book and prevented him from completing
his task. As a close friend and collaborator for many years, I knew how much he wanted
to conclude this project and, therefore, took it upon myself to finish the last stages
of editing.
I would like to take this opportunity to thank the Elsevier Publishing Company
and all the contributors who showed so much patience and understanding and thus
helped me to complete this difficult task.
I hope that this posthumously published book will help keep alive the memory of
Saadia and his outstanding contribution to science.
Mariana Mantel
CONTRIBUTORS TO THIS VOLUME
S. Amiel Israel Atomic Energy Commission, Soreq Nuclear Research Center, Yavne 70600,
Israel
D.A. Becker Office of Recycled Materials, U.S. Department of Commerce, National Bureau of
Standards, Washington, DC 20234, U.S.A.
G. Desaedeleer Department of Oceanography, The Florida State University, Tallahassee, FL 32306,
U.S.A.
H. Feldstein Nuclear Chemistry Department, Soreq Nuclear Research Center, Yavne 70600,
Israel
C. Gilath Isotope Applications Department, Israel Atomic Energy Commission, Soreq
Nuclear Research Center, Yavne 70600, Israel
G. Goles Department of Chemistry and Geology, Center for Volcanology, University of
Oregon, Eugene, OR 97403, U.S.A.
C.A. Grimm National Bureau of Standards, Washington, DC 20234, U.S.A.
P.D. LaFleur Analytical Chemistry Division, National Bureau of Standards, Washington
DC 20234, U.S.A.
M. Mantel Israel Atomic Energy Commission, Soreq Nuclear Research Center, Yavne 70600,
Israel
R.M. Parr Department of Research and Isotopes, International Atomic Energy Agency,
Vienna International Centre, POB 200, A-1400 Vienna, Austria
M. Peisach Chemistry Division, Southern Universities Nuclear Institute, P.O. Box 17,
Faure, C.P. 7131, Republic of South Africa
I. Perlman Department of Archeometry, Institute of Archeology, Hebrew University of
Jerusalem, Jerusalem, Israel
H.L. Rook Analytical Chemistry Division, National Bureau of Standards, Washington,
DC 20234, U.S.A.
E. Yellin International Atomic Energy Agency, KSrnter Ring 11, P.O. Box 590, A-1011
Vienna, Austria
H.P. Yule NUS Corporation, 4 Research Place, Rockville, MD 20850, U.S.A.
Chapter 1 Introduction
S. AMIEL
The purpose of this book is to supply the reader with an understanding of the basic
principles of nondestructive neutron activation analysis and to explain why and when
it should be used, why it works as it does, what it has to offer and how it should be
applied.
Since its discovery in 1936 by G. Hevessy and H. Levy, neutron activation analysis
has progressed rapidly and has become today a versatile and sensitive analytical tool in
all branches of science and technology. Based on the highly characteristic and well-
defined nuclear properties of the elements, this technique is close to an ideal nonde-
structive analytical method. It fulfills the two basic requirements of nondestructive
techniques: specificity - the ability to correlate directly and unambiguously the signal
obtained with the element sought, and selectivity — the possibility of measuring the
element in question in the presence of other elements which emit signals of the same
nature.
The fundamental principles on which activation analysis is based have remained un-
changed, but the tremendous development which has taken place in the last decade in
electronic equipment in general and in detection instrumentation (such as Ge(Li) and
Si(Li) detectors) in particular, gave impetus to the improvement of this technique. It
could thus be introduced into other fields, such as medicine, biology and environmen-
tal studies where high sensitivity is required. Furthermore, the combination of non-
destructive neutron activation with computerized data processing imparts to the
method high accuracy, precision and speed.
Though very attractive, it is utopic to believe that nondestructive activation analy-
sis can be universally applied. The analyst must be result-oriented and not technique-
minded. He has to be aware of the limitations of the method and decide from case to
case what he may achieve and at what price {e.g. rapidity vs. high errors or high sensi-
tivity vs. selectivity).
This book should be of interest to three types of prospective readers: analytical
chemists, nuclear and radiochemists, and other scientists who may utilize the potential
of activation analysis. It is intended to provide each of these three groups with the in-
formation which they may lack on the use of nondestructive activation analysis. The
analytical chemist will find here a means to evaluate the relative merits of this technique
and compare them with those with which he is already familiar. To the nuclear chemist,
the book will explain the analytical considerations involved in possible applications of
the method. For others, e.g. engineers, physicians, etc., who are aware of their require-
ments, pertinent information is supplied in specific sections concerned with applications
of the method to their particular field.
The layout of the book parallels the three steps followed in nondestructive neutron
activation analysis, i.e. irradiation, measurement and evaluation of results. Basic prin-
ciples which may be found in many other books or monographs on activation analysis
are not dealt with in detail. Thus Chapter 2 "Irradiations" is only a very brief descrip-
tion of reactors and radioactive neutron sources, but provides enough information to
1
help the reader who has no experience in this subject, to comprehend it.
Chapter 3 "Measurement and Techniques" and Chapter 4 "Data Processing" are
basic chapters for all readers, since they deal with techniques of measurement and
calculation which make possible the successful use of nondestructive activation analysis,
and which correctly applied make it the efficient and advantageous technique described.
Finally, Chapter 5 "Applications" shows how nondestructive activation analysis may
be applied to different disciplines and the impact it had, due to its high accuracy and
precision, on the better understanding, in recent years, of many previously unsolved
problems.
The "Appendix" contains lists of gamma rays arranged by energy and by emitting
isotope. This information is essential for every analyst who uses nondestructive acti-
vation analysis. I decided not to include a list of methods reported in the literature for
the determination of specific elements by nondestructive activation analysis, since I
wanted this book to deal with general principles and relevant examples and not to be-
come a bibliographic encyclopedia.
The advantage of having different contributors, each an expert in his own field, will
be realised by the reader. Each chapter is meant to be independent and reference to
other chapters is kept to a minimum. However, a small amount of repetition has been
found necessary. It appears that the difference in approach used by the individual
authors of the various chapters has made this duplication beneficial. As a result, it is
not necessary to read the chapters consecutively and the reader can therefore restrict
himself to his particular field of interest.
An edited book could never be published without the cooperation of the various
contributors. To the authors, I would like to extend my thanks for their enthusiastic
cooperation, their readiness to conform to the general outline and to make changes in
their original draft. The contributions of those who helped in the preparation of a text
from which galley proofs can be produced is gratefully acknowledged. Special thanks
are due to Dr. Mariana Mantel who assisted me from the first concept throughout the
entire editing of the book. Finally, I hope that all these combined efforts have succeed-
ed in fulfilling the aim of the book, to be a guide for the better understanding of the
principles and possible applications of nondestructive neutron activation analysis with
a nuclear reactor.
2
Chapter 2
IRRADIATION
S. AMIEL and H. FELDSTEIN
Nuclear Chemistry Department, Soreq Nuclear Research Center, Yavne (Israel)
I. INTRODUCTION
The available neutron irradiating facilities provide a wide range of neutron fluxes
and energies. The choice of the most suitable system should be based on the specific
analytical requirements of the problem. A brief description of neutron irradiation
facilities and their application to specific problems is given here.
II. NEUTRON SOURCES
The three main sources of neutrons for irradiation are:
(A) Nuclear reactors
(B) Radioactive neutron sources
(C) Electron and ion accelerators which produce high energy neutrons by (7, xn),
D-D or D-T reactions.
Nuclear reactors, with their high neutron fluxes give the most intense irradiation and
consequently permit extremely high sensitivities for the detection and quantitative
determination of various elements. Radioactive neutron sources, though several orders
of magnitude less intense than the reactors, are very convenient for elemental analysis
in situ and there is increasing demand for devices of this kind for use in industry and
geological surveys. The third type of neutron source listed, accelerators, will not be
treated here, as such a discussion is not within the scope of this book.
A. Nuclear reactors
Reactor neutrons are classified according to their energy into three groups: fast
neutrons (fission spectrum), resonance neutrons and thermal neutrons.
Fast neutrons usually consist of partially moderated and largely unmoderated fission
neutrons, the spectrum of which is given by the practical approximation [1]:
n(E) = 0.77 (E)V2 e~°'116E
where n(E) is the number of neutrons having energy E, expressed in MeV.
Table 1 shows the relative abundance of neutrons at and above certain energies. Fast
neutrons are most abundant in the immediate proximity of the fuel elements; their abun-
dance decreases rapidly with distance from the fuel. Light-water-moderated reactors
provide neutron fluxes with relatively high ratios of fast to slow neutrons (< 1) while
in graphite piles and heavy water reactors the ratio is much lower (0.1 and below). The
3
relative number of fast neutrons is decreased in light-water reactors provided with
reflectors.
TABLE 1
NEUTRON SPECTRUM FROM THE FISSION OF 235U BY THERMAL NEUTRONS [l]
E N(E) F(E)
(MeV) Fraction of neutrons at E Fraction of neutrons
per MeV interval above E
0 0 1.0000
0.25 0.2905
0.50 0.3471 0.8531
0.75 0.3580
1.00 0.3472 0.7024
1.50 0.2979 0.5386
2.0 0.2390 0.4024
2.5 0.1843 0.2950
3.0 0.1383 0.2131
3.5 0.1019 0.1523
4.0 0.07383 0.1076
4.5 0.05288 0.07551
5.0 0.03750 0.05259
5.5 0.02635 0.03639
6.0 0.01838 0.02505
6.5 0.01274 0.01715
7.0 8.779X10"6 0.01169
7.5 6.019 xl0~3 7.939 xl0~3
8.0 4.107xl0~3 5.372 xlO-3
8.5 2.791 xl0~3 3.621 xl0~3
9.0 1.889 xl0~3 2.434 xl0~3
9.5 1.274 xl0~3 1.634x10^
10.0 8.57 xl0~* 1.092x10^
11.0 3.84x10"* 4.89 xl0~^
12.0 1.70x10^ 2.15x10"^
The thermal neutron fluxes available in the core of the reactor range from 1012 to
1014 n cm^s""1 and in pulsed reactors may be as high as 1016 n cnT~ s~ [2]. These
high fluxes render activation analysis by thermal neutrons (n, y reactions) an extremely
sensitive analytical tool.
However, not all elements are suitable for (n/y) activation analysis. Some of these
may be determined by (n,p), (n,a), (n,n') or (n,2n) [3] reactions with fast neutrons.
Reactors may be used as fast neutron sources by applying thermal and resonance
4