Compatibility studies of several molten uranium and thorium alloys in niobium, tantalum, and yttrium

155 Pages·2017·2.56 MB·English

Ames Laboratory Technical Reports Ames Laboratory
2-1964
Compatibility studies of several molten uranium
and thorium alloys in niobium, tantalum, and
yttrium
Robert James Cash
Iowa State University
Ray M. Fisher
Iowa State University
Merl R. Core
Iowa State University
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Recommended Citation
Cash, Robert James; Fisher, Ray M.; and Core, Merl R., "Compatibility studies of several molten uranium and thorium alloys in
niobium, tantalum, and yttrium" (1964).Ames Laboratory Technical Reports. 60.
http://lib.dr.iastate.edu/ameslab_isreports/60
This Report is brought to you for free and open access by the Ames Laboratory at Iowa State University Digital Repository. It has been accepted for
inclusion in Ames Laboratory Technical Reports by an authorized administrator of Iowa State University Digital Repository. For more information,
please [email protected].
Compatibility studies of several molten uranium and thorium alloys in
niobium, tantalum, and yttrium
Abstract
Niobium, tantalum, yttrium, and Inconel have been used to contain molten aluminum, lead, tin, zinc, and
several of their respective uranium and thorium alloys for various times up to 3000 hours and at temperatures
ranging from 600 to 1100° C. Altogether 76 capsule tests were run, almost all in a static isothermal condition.
Tantalum showed the best resistance followed by niobium, Inconel, and yttrium respectively. The systems,
lead in tantalum and lead in niobium, showed the greatest potentials for possible liquid-metal fuel carrier
systems. An alloy of uranium-bismuth-tin contained in tantalum also exhibited promising possibilities . The
tabulated test data include a classification of the type of corrosion attack which occurred and a measured value
of the amount of corrosive penetration. Each test was also given an arbitrary rating for easy reference
comparisons. A number of photomicrographs are included for each set of tests.
Disciplines
Engineering | Metallurgy
This report is available at Iowa State University Digital Repository:http://lib.dr.iastate.edu/ameslab_isreports/60
IS-888
IOWA STATE UNIVERSITY
COMPATIBILITY STUDIES OF SEVERAL
MOLTEN URANIUM AND THORIUM ALLOYS
IN NIOBIUM, TANTALUM, AND YTTRIUM
by
Robert James Cash, Ray M. Fisher and
Merl R. Core
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RESEARCH AND
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REPORT
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U.S.A.E.C.
IS-888
Engineering and EquiP.ment (UC-38)
TID-4500, June 1, 1964
UNITED STATES ATOMIC ENERGY COMMISSION
Research and Development Report
COMPATIBILITY STUDIES OF SEVERAL
MOLTEN URANIUM AND THORIUM ALLOYS
IN NIOBIUM, TANTALUM, AND YTTRIUM
by
Robert James Cash, Ray M. Fisher and
Merl R. Core
February 1964
Ames Laboratory
at
Iowa State University of Science and Technology
F. H. Spedding, Director
Contract W-7405 eng-82
ii
IS-888
This report is distributed according to the category Engineering and
Equipment (UC-38) as listed in TID-4500, June 1, 1964.
LEGAL NOTICE--------.
r--------
This report was prepared as an account of Government sponsored work.
Neither the United States, nor the Commission, nor any person acting
on behalf of the Commission:
A. Makes any warranty or representation, expressed or implied,
with respect to the accuracy, completeness, or usefulness of
the information contained in this report, or that the use of any
information, apparatus, method, or process disclosed in this
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B. Assumes any liabilities with respect to the use of, or for
damages resulting from the use of any information, apparatus,
method, or process disclosed in this report.
As used in the above, "person acting on behalf of the Commission"
includes any employee or contractor of the Commission, or employee
of such contractor, to the extent that such employee or contractor of the
Commission, or employee of such contractor prepares, disseminates,
or provides access to, any information pursuant to his employment or
contract with the Commission, or his employment with such contractor.
Printed in USA. Price $ 2. 75 Available from the
Office of Technical Services
U. S. Department of Commerce
Washington 25, D. C.
111
TABLE OF CONTENTS
Page
INTRODUCTION l
CORROSION BY LIQUID METALS 9
Types of Corrosion Attack l 0
Pure metals l 0
Alloys ll
Impurities ll
High damage factor 24
Medium damage factor 24
Low damage factor 25
Evaluation of the Degree of Corrosion Attack 25
Rate-Controlling Processes of the Corrosion Mechanisms 29
Corrosion Attack Inhibitors 35
OBJECT OF THE INVESTIGATION 39
DISCUSSION OF THE PROBLEM 40
Selection of the Containment Metals 40
Selection of the Liquid-Metal Alloys 46
REVIEW OF LITERATURE 55
Corrosion by Liquid Aluminum 55
Corrosion by Liquid Lead and Lead Alloys 57
Corrosion by Liquid Tin and Tin Alloys 61
Corrosion by Liquid Zinc and Zinc Alloys 63
EXPERIMENTAL PROCEDURES 66
Corrosion Test Procedures 67
Methods of Specimen Examination 75
RESULTS AND DISCUSSION 78
Corrosion by Aluminum and Uranium-Aluminum 79
iv
Page
Corrosion by Lead and Its Thorium and Uranium Alloys 85
Corrosion by Tin and Its Thorium and Uranium Alloys 95
Corrosion by Zinc 122
CONCLUSIONS 128
RECOMMENDATIONS FOR FURTHER STUDY 131
BIBLIOGRAPHY 1 3 5
APPENDIX A 141
Chemical Analyses of Metals and Alloys Used in the
Investigation 142
APPENDIX B 146
v
IS-888
COMPATIBILITY STUDIES OF SEVERAL MOLTEN URANIUM ,:,
AND THORIFM ALLOYS IN NIOBIUM, TANTALUM AND YTTRIUM
Robert James Cash, Ray W. Fisher and Merl R. Core
ABSTRACT
Niobium, tantalum, yttrium, and Inconel have been used to contain
molten aluminum, lead, tin, zinc, and several of their respective uranium
and thorium alloys for various times up to 3000 hours and at temperatures
ranging from 600 to 1100° C. Altogether 76 capsule tests were run, almost
all in a static isothermal condition. Tantalum showed the best resistance
followed by niobium, Inconel, and yttrium respectively. The systems, lead
in tantalum and lead in niobium, showed the greatest potentials for possible
liquid-metal fuel carrier systems. An alloy of uranium-bismuth-tin
contained in tantalum also exhibited promising possibilities . The tabulated
test data include a classification of the type of corrosion attack which
occurred and a measured value of the amount of corrosive penetration.
Each test was also given an arbitrary rating for easy reference comparisons.
A number of photomicrographs are included for each set of tests.
A background of the advantages and disadvantages of fluid-fuel reactors
are compared with those for solid-fuel reactors. Differences between
aqueous fuels and liquid-metal fuels are also discussed. The various types
of corrosive attack of solid metals by liquid metals are defined and
illustrated with several photomicrographs. The variables affecting liquid
metal corrosion attack are given and driving forces for the various types
of attack presented. Methods of corrosion inhibition are mentioned. The
various criteria for selecting fuel and fertile alloys and suitable container
materials were also considered.
':' This report is based on an M.S. thesis by Robert James Cash which
was presented February, 1964, to Iowa State University, Ames, Iowa.
INTRODUCTION
The greatest stimulus to the development of liquid metals technology
was undoubtedly the advent of nuclear energy and the concept of the liquid
metal-fuel reactor. With the growth of the atomic energy program, liquid
metals were first considered as reactor coolants and later as fuel carriers.
In addition, liquid metals were suggested for pyrometallurgical processing,
that is, high temperature fuel reprocessing. Present trends of develop
ment in nuclear power reactors are towards higher operating temperatures
to improve thermal efficiency, and towards more irradiation-resistant
fuels to achieve increased reactor stability and greater fuel utilization.
The liquid-metal-fuel-reactor concept was first suggested by von
Halban and Kowarski in 1941 (51), but it did not receive much attention
until 1947. The first so-called liquid-metal-fuel-reactor (LMFR) as pro
posed by the Nuclear Engineering Department of Brookhaven National Labora
tory was a thermal, power-breeder reactor. A solution of uranium in bis
muth was selected for the fuel because of the low melting point and low
thermal neutron-absorption cross section of bismuth. Moreover, bismuth has
a high boiling point [l477°C; (65)] which makes possible the high tempera
ture operation of a bismuth-cooled reactor at fairly low pressures. One
of the most outstanding features of the LMFR is the proposed method for
fuel reprocessing. Pyrometallurgical experiments (5, 56) have shown that
the removal of volatile fission products can be effected by vacuum degas
sing, whereas nonvolatile fission products from the fluid fuel can be
removed by extraction with a fused salt. Furthermore, this process can
be put on a continuous basis which should show a low operating cost.
2
Modern conventional power plants have an approximate thermodynamic
efficiency of 40 per cent. For a nuclear power plant to achieve simi Jar
efficiencies, it is necessary to have the reactor outlet temperature above
500°C. With the LMFR, such temperatures are obtainable, and it repre
sents one of the few potentialities for producing electric power com
petitive with the best of the present conventional steam power plants.
Moreover, the flexibility of liquid-metal-fuel systems is such that they
range over several different reactor categories. Liquid-metal-fuel
reactors may be designed as fast, intermediate, or thermal systems, with
either circulating or static fuel systems (44).
In order to understand better the characteristics and development
problems of a liquid-metal-fuel reactor, fluid- and solid-fuel reactors
should be compared. In particular, a distinction between the features of
fluid fuels and those of liquid-metal fuels should be made (1, 36, 44,
46, 47, 60).
The advantages of a reactor using a circulating fluid fuel over one
with solid-fuel elements can be listed as follows:
1. Simple design and structure Fluid-fuel reactors can employ
external heat exchangers separate from the core region, so that the nuclear
requirements of the core do not have to compromise with the heat flow
requirements of the exchanger since both need not be satisfied at the same
place. Therefore, materials of high neutron absorption cross sections,
which could not be used in the core of a thermal reactor, could be used for
the heat exchanger construction. Furthermore, the heat transfer problem
is simpler, because, in addition to conduction, advantage can be taken of
the flui d fuel in transferring heat.