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Патент USA US3063933

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3,063,923
Patented Nov. 13, 1962
2
3,063,923
Stanley W. Mayer, Canoga Park, Calii, assignor, by
FUSED REACTOR FUELS
mesne assignments, to the United States of America
as represented by the United States Atomic Energy
Commission
No Drawing. Filed June 1, 1959, Ser. No. 817,087
13 Claims. (Cl. 204—154.2)
(b) halogen, wherein said halogen is in the form of at
least one member selected from the class consisting of
metal halides, metal halosul'fonates and metal halophos
phates, (c) phosphorus, vwherein said phosphorus is in
the form of at least one constituent selected from the
class consisting of oxides of phosphorus, metal phos
phates, metal phosphites and metal halophosphates, and
(d) metal oxides, wherein the amount of at least one
This invention relates to novel reactor fuel composi
tions. More particularly, this invention relates to novel
fused reactor fuel composition.
member selected from the class consisting of halogen
and sulfur is at least about one atom percent based on
the amount of the sum of said sulfur, halogen and phos
phorus ‘atoms in said composition; and wherein the sum
Nuclear reactor fuels are compositions containing one
of said sulfur entities, said phosphorus constituents and
or more of the ?ssionable elements uranium, thorium
said halogen compounds in said composition which do
and plutonium. Various compositions useful as re
not contain uranium, thorium or plutonium atoms, is
actor fuels have been suggested and tried. Fused salt 15 at least about 60 weight percent based on the combined
fuels such as the NaF-UF4 system have been used in the
weight of the components of the composition which are
Aircraft Reactor Experiment. The LMFR reactor at
the Brookhaven National Laboratory employed a Bi-U233
free of the uranium, thorium and plutonium elements.
fuel with a Th3Bi5-Bi blanket. Still ‘another type is the
aqueous homogeneous reactor which employs such fuels
sodium metaphosphate and uranyl sulfate in proportions
as an aqueous uranyl sulfate solution. Each of these
types of reactors, of course, has a number of disadvan
solution has a solidi?cation temperature of 352° C.
tages.
The LMFR has a low solubility of ?ssionable
uranium in bismuth, thus requiring an exceptionally
large core volume to reach criticality. Another disadvan
tage of the LMFR is that molten bismuth is readily
attacked by oxygen upon exposure to air. The ?uoride
salts in the fused salts reactor are found to be very cor
rosive which puts limitation on the type of material that
can be used to contain the core solution. The aqueous
homogeneous fuel reactors are handicapped by a low
operating temperature. To attain greater power output,
the aqueous homogeneous reactors are operated at high
pressure. This places a restriction on the type of ma
terial that can lbe used in the fabrication of the core
which, in effect, must be a high pressure vessel.
A
need exists, therefore, for a reactor fuel which has a
low vapor pressure at high temperatures, has a low solidi
?cation temperature and has relatively low susceptibility
to radiation damage.
It is, therefore, an object of this invention to pro
vide a composition suitable for use as a reactor fuel
which has a low vapor pressure in the molten state.
Another object of this invention is to provide a fused
reactor fuel which has a low solidi?cation temperature.
Another object is to provide a nuclear reactor fuel which
has a relatively low susceptibility to radiation damage.
Still another object of this invention is a nuclear re
An example of such a fuel is a composition containing
such as to provide 35.4 weight percent uranium. This
serves well as a nuclear reactor fuel composition.
It
An
other fuel composition is one which, in addition to the
sodium metaphosphate-uranyl sulfate solution mentioned
above, contains up to about 40 weight percent of a
' metal oxide such as sodium oxide.
When the ?ssionable fuel employed in the composi-.
tion contains uranium, the uranium can be in the form‘v
of oxides, halides or oxyacid salts, or mixtures of two
or more of these forms. When the uranium is in the
form of the oxide, the latter can be any of the well
known oxides of uranium as, for example, U02, U308
and U03. When the uranium is employed in the form
of the halides, it can be in the form of any of the halides
as, for example, U014, UF4, etc. UF4, however, is the
one preferred when the halide of uranium is employed
because ?uorine has a lower neutron capture cross sec
tion than do the other halogens. When the uranium is
employed in the form of an oxyacid salt, it can be used
in the form of one or more of salts such as uranyl
sulfate, UO2SO4, uranyl nitrate, UO2(NO3)2, uranyl
pyrosulfate, UO2S2O7, uranyl sul?te, UO2SO3, uranyl
chromate, UO2CrO4, uranyl phosphates, UO2(PO3)2,
(UO2)'2P2O7, uranyl i'luorophosphate, (UOZ)3(FPO3)2,
uranyl carbonates, UO2CO3, Na2UO2(CO3)-2, uranyl
molybdate, UO2MoO4, uranyl silicate, UO2SiO3, U(SO4) 2,
UPgOq, U(PO3)4, U(PO3)3, etc.
When one ‘of the fuels employed is thorium, it can be
actor fuel composition which is stable in the presence 50 in the form of an oxide, a halide or an oxyacid salt or a
of air. Other objects of this invention will become more
mixture of two or more different forms as in the case of
apparent from the discussion which follows.
uranium. For example, the thorium can be in the form
The above and other objects of this invention are
of thorium dioxide, ThOz. The fuel can also be in the
accomplished by providing ?ssionable material in the
form of fused salt compositions wherein the composi
tions contain sulfur and/or halogen in the form, for
example, of metal sulfates, metal halides, and/or metal
halosulfonates. The presence of such sulfur and/or halo
gen compounds improves the solubility of the ?ssionable
metal salts.
Hence, an embodiment of this invention
is a composition of matter useful as a nuclear reactor
fuel comprising (1) from about 0.01 to about 50 weight
percent based on the total weight of said composition
of at least one element selected from the class consisting
of uranium, thorium and plutonium, wherein said do
ment is present in the form of at least one component
selected from the class consisting of oxides, halides ‘and
oxyacid salts, with (2) at least one member selected
from the class consisting of (a) sulfur, wherein said
form of one or more halides such as, for example,
thorium ?uoride, ThF4, thorium chloride, ThCl4, ThBr4,
etc. When oxyacid salts of thorium are employed, they
can be any of one or more oxyacid salts, as, for ex
ample, T116002, T110604), T116207)» Th(NO3)4,
ThO(NO3)2, thorium carbonate, thorium chromate, tho
rium molybdate, thorium ?uosulfonate, etc.
When plutonium is employed as a fuel, it too can be
in at least one form such as oxides of plutonium, halides
of plutonium, and oxyacid salts of plutonium. For ex
ample, the plutonium can be present in the form of one
or more oxides such as PuO2, PuO3, Pu2O3, and PuaOg.
As a halide, the plutonium can be present in the form of
PuF3, PuF4, PuBr4, PuCl3, PuCl4, PuClF3, etc., or a mix
ture of two or more of these.
When the halides of the
sulfur is in the form of at least one entity selected from 70 ?ssionable materials are included in the reactor fuel com
the class consisting of oxides of sulfur, metal sulfates,
metal sul?tes, acids of sulfur and metal halosulfonates,
positions, it is preferred to use the ?uorides of the
elements since these are more stable than the other halo
3,063,923
3
4
gen derivatives and have lower neutron capture cross
composition of at least one element selected from the
sections. When the oxyacid salts of plutonium are used,
class consisting of uranium, thorium and plutonium,
they can be one or more of the following: PuO2SO4,
wherein said element is present in the form of at least one
PuO2S2O7, plutonium phosphates such as PuP2Oq, plu
component selected from the class consisting of oxides,
tonium metaphosphates such as PuO2(PO3)2, Pu(PO3)4,
plutonium nitrates such as PuO2(NO3)2, plutonium
carbonates such as PuO2CO3, plutonium chromate,
halides and oxyacid salts with (2) at least one member
selected from the class consisting of (a) sulfur, wherein
said sulfur is in the form of at least one entity selected
Pu(CrO4)2, plutonium molybdate, PuO2MoO4, etc.
from the class consisting of oxides of sulfur, metal sul
The sulfur can be present in the composition in the
fates and acids of sulfur and (b) halogen, wherein said
form of oxides of sulfur and metal sulfur compounds such 10 halogen is in the form of at least one member selected
from the class consisting of metal halides, metal halo
as metal sulfates, metal sul?tes, metal halosulfonates and
sulfonates and metal halophosphates.
acids of sulfur. Examples of oxides of sulfur are sulfur
One of the advantages of the compositions of this in
trioxide, S03, and S201. When present in the form of
metal sulfur compounds, the sulfur can be present as the
vention is that a ‘considerable amount of nuclear ?ssion
sulfate, sul?te or halosulfonate of any metal. By sulfates 15 able material is brought into solution at relatively low
is included all the various sulfates as, for example, ortho
temperatures. Also, the viscosity of the melt is consider
sulfates, pyrosulfates, hydrogensulfates, peroxisulfates,
etc. For example, the sulfates can be the alkali metal
sulfates of group IA of the periodic table of the ele
ments. The periodic table referred to in this writing is
that found in the “Handbook of Chemistry and Physics,”
pages 392, 393 (19554956), 37th edition, published by
the Chemical Rubber Publishing Company, Cleveland,
ably reduced facilitating transfer of the composition
through heat exchangers, and ?ssion product removal.
To insure a molten state at lower temperatures when
sulfur-containing compounds other than compounds of
the ?ssionable material are employed, it is preferable
that the amount of sulfur which is present in the form
of alkali metal sulfur-containing compounds is at least
Ohio. Non-limiting examples of group IA alkali metal
sulfur-containing compounds are lithium sulfate, lithium
hydrogen sulfate, lithium pyrosulfate, lithium ?uosulfo
nate, sodium sulfate, sodium hydrogen sulfate, sodium
pyrosulfate, sodium peroxidisulfate, sodium sul?te, sodi
um ?uosulfonate, potassium sulfate, potassium acid sul
?ssionable material is enhanced in the case where metal
fate, potassium pyrosulfate, potassium peroxidisulfate,
30 sulfur-containing compounds other than those of the
rubidium sulfate, potassium fluosulfonate, rubidium hy
drogen sulfate, rubidium pyrosulfate, rubidium ?uosulfo
nate, cesium sulfate, cesium hydrogen sulfate, cesium
?ssionable material are employed, when the amount of
sulfur in the composition is at least about 25 atom per
about 10 atom percent.
Sulfur in the form of alkali
metal sulfur-containing compounds within the range of
from about 10 to about 90 atom percent sulfur are found
to provide good fuel compositions. It is also found that
the solubility of the thorium, uranium and plutonium
cent. Sulfur components in the composition, wherein
the atom percent sulfur in the form of alkali metal sulfur
pyrosulfate, etc. Non-limiting examples of group IIA
sulfur-containing compounds are magnesium sulfate, cal 35 containing compounds is from about 25 to about 75 atom
percent, are found to be advantageous in this respect and,
cium sulfate, strontium sulfate, strontium hydrogen sul
therefore, represent an especially preferred composition
fate, barium sulfate, barium peroxidisulfate, etc. Non
with respect to the type of metal sulfur-containing com
limiting examples of group 1118 sulfur-containing com
pounds present.
pounds are lanthanum sulfate, ceric sulfate, cerous sul
fate, samarium sulfate, gadolinium sulfate, yttrium sulfate, 40 As stated here‘inabove the amount of uranium, thorium
rand/or plutonium in the composition can vary from
etc. Non-limiting examples of group IVB metal sulfur
‘about ‘0.01 weight percent to about 50‘ weight percent
containing compounds include titanium sulfate and zir
based on the total weight of the composition. Natural
conium sulfate. Non-limiting examples of group VB
uranium containing about 0.71 weight percent U-235
sulfur-containing compounds are tantalum sulfate and
is used as well as uranium that is enriched in the U-235
niobium sulfate. Non-limiting examples of group VIE
isotope. The U-235 isotope is also used by itself as is
sulfates include chromium sulfates, CrSO4, and
the U-233 isotope. Uranium containing less ‘than 0.71
weight percent U—235 is also used as well as combina
tions of various uranium isotopes. Since it is preferable
chromium sul?te, Cr2(SO)3. Non-limiting examples of
group VIIB sulfur-containing compounds include manga
nese sulfate. Non-limiting examples of group VIII metal
sulfur-containing compounds include ferric sulfate, fer
rous sulfate, cobaltic sulfate, cobaltous sulfate, rhodium
sulfate, nickel sulfate, etc. Non-limiting examples of
group IB sulfur-containing compounds are cupric sulfate,
cuprous sulfate and silver sulfate.
Non-limiting exam
ples of group IIB sufur-containing compounds include
zinc sulfate and cadmium sulfate.
Non-limiting exam
ples of group IIIA Sulfur-containing compounds include
aluminum sulfate, gallium sulfate, indium sulfate, thallic
sulfate and thallous sulfate. Non-limiting examples of
group IVA sulfur-containing compounds include stannic
sulfate, stannous sulfate, lead sulfate and basic lead sul
fate.
The acids of sulfur include sulfuric acid, H2504 and
pyrosulfuric acid, H2S2O7. Sulfur can also be present
in the form of the sulfates of the ?ssionable material such
as uranyl sulfate, uranyl pyrosulfate, thorium sulfate and
plutonium sulfate, etc.
When the reactor fuel composition of this invention is
composed of ?ssionable material together with the sulfate,
50 ‘to have as high ‘a concentration as possible of the ?ssion
able material, namely, the uranium, thorium and/or
plutonium, it is preferred that the composition contain
from about 0.1 to about 50 weight percent of the elements
based on the total weight of the composition. Another
preferred embodiment of this invention are compositions
containing from about 1 to about 50 weight percent of
the thorium, uranium and/or plutonium elements since
the more concentrated the latter three elements are in
the composition the more economical is the fuel for use
in a nuclear reactor. Especially preferred are composi
tions containing from about 10 to about 36 weight per
cent of one or more of the thorium, uranium and plu
tonium elements since this range of concentrations of
these elements provides the most readily preparable com
positions for use in homogeneous fused liquid fuel re
actors operating at comparatively low temperatures with
highest e?iciency. For example, one of the preferred
compositions is a uranium-containing solution wherein
the uranium is present in about 10 weight percent in the
form of uranyl sulfate in a solution of sodium sulfate and
zinc sulfate wherein about 25 atom percent of the sulfur
is present in the form of sodium sulfate.
‘In addition, the compositions can contain up to about
its composition comprises (1) from about 0.01 to about
40 weight percent of the total weight of the components
50 weight percent based on the total weight of said 75 other than the uranium, thorium and/or plutonium com
3,063,923
5
6
pounds, of any metal oxide or mixture of metal oxides.
TABLE 1—Continuedv
Non-limiting examples or" metal oxides that may be pres
ent are lithium oxide in the zmount of one weight percent
or gadolinium oxide in the amount of 40 weight percent.
No.
Non-limiting examples of other oxides are sodium oxide,
potassium oxide, cesium oxide, barium oxide, zirconium
oxide, vanadium oxide, tungsten oxide, manganese oxide,
‘ferric oxide, rhodium oxide, platinum oxide, silver oxide,
zinc oxide, thallium oxide, lead oxide, antimony oxide,
Component Parts by Weight percent
weight
U, Th or Pu
4_____
36
10 (10% U—235)-
Remarks
1 weight percent
OuO based on
components other
than UOzSOc.
25 (natural U)-.. 10 atom percent of
selenium oxide, bismuth oxide, etc. Thus the oxide is an 10
oxide of a metal having an atomic number of from 3 to
about 83.
the S present is
in the form of
alkali metal
sulfates.
When halogen is present in the composition, it is in the
form of at least one member selected from the class con
90 atom percent of
the S present is
in the form 01'
alkali metal
sulfates.
sisting of metal halides, metal halosulfonates and metal
halophosphonates, wherein the metal has an atomic num
ber of vfrom 3 to 93. Non-limiting examples of such
halogen-containing compounds include metal halides such
as lithium ?uoride, sodium ?uoride, potassium ?uoride,
rubidium ?uoride, cesium ?uoride, calcium ?uoride, 20
lanthanum ?uoride, titanium ?uoride, vanadium ?uoride,
chromium ?uoride, manganese ?uoride, ferric ?uoride,
thorium ?uoride, uranium ?uoride, plutonium ?uoride,
50 _____________ __
75 atom percent of
the S is present in
the form of an
50 ..... _'_ ______ -
alkali metal
sulfate.
25 atom percent of
the S is present in
the form of an
etc.; metal halosulfonates such as lithium ?uosulfonate,
alkali metal sul~
fate.
sodium ?uosulfonate, potassium ?uosulfonate, rubidium
?uosulfonate, cesium ?uosultonate, calcium ?uosultonate,
uranyl ?uosulfonate, thorium ?uosulfonate, the ?uosul
fonates of plutonium, etc.; metal halophosphates such as
lithium ?uorophosphate, sodium mono?uorophosphate,
40 weight oxides of
sodium hexa?uorophosphate, potassium ?uorophosphate,
metals other than
oxides of ?ssion
rubidium ?uorophosphate, cesium ?uorophosphate, stron
tium ?uorophosphate, ferric ?uorophosphate, thorium
?uorophosphate, uranium ?uorophosphate, uranyl ?uoro
' able material
based on weight of
conpoments other
phosphate, plutonium fluorophosphate, etc.
than Th(SO4)2.
1 weight percent
12-.-.
The fuel compositions of this invention are prepared by 35
metal oxide pres
heating the components in a container made of a suitable
ent based on
material such as, for example, Inconel, stainless steel,
borosilicate glass, quartz, etc. The obtaining of a sub
stantially homogeneous solution is aided by stirring or
otherwise agitating the ‘composition during and after melt 40
ponents other than
weight of com
Th(SO|)2.
ing. The components may be added to the container
in which they are melted in any order. For example,
‘all the components may be added to the container before
the heating is commenced.
14--.
90 atom percent of
the sulfur is in
the form of alkali
metal sulfates.
15.--
25 atom percent of
the sulfur is in
Alternatively, the compo
nents may be mixed in the powdered state before placing
in the container for heating purposes. In another varia
,
10 atom percent of
the sulfur is in
the form of alkali
metal sulfates.
tion of preparing the molten solution, the component
having the lowest melting point is added ?rst. Heat is
the form of an
then applied to melt the component as say, ‘for example,
alkali metal sul
fate.
16-.-.
the application of heat to sodium metaphosphate. The 50
other components such as sodium sulfate and uranyl sul
fate are added to the molten sodium metaphosphate while
continuing to heat the container until the entire com
17---
40 weight percent
18____
oxides of metals
other than oxides
of ?ssionable
material based on
position is molten.
Non-limiting examples of speci?c compositions of this 55
invention containing a ?ssionable material and various
sulfur and halogen components as well as oxides are
components other
th8DrPl1203.
1 Weight percent
19---
given in the following table.
oxides of metal
60
TABLE I
20..-
K23
Component Parts by Weight percent
weight
U,
or Pu
other than oxides of
?ssionable material
based on weight
of components
other than P1103.
l0 atom percent
sulfur in form of
alkali metal sul
Remarks
fur compounds.
65
75 atom percent
‘ sulfur in form of
0.01 (U—235).-_.
22....
alkali metal sul
fates.
0.1 (U-235) ____ __
1 (20% ‘(I-235)--
40 weight percent
70
oxides of metals
other than oxides
of ?ssionable
material based on
weight of com
ponents other
than U108.
Another form of the compositions of this invention is
75 one in which the uranium, thorium and/or plutonium
3,063,923
?ssionable material together with sulfur compounds con
phosphorus is in the form of oxides of phosphorus, metal
36 percent are exceptionally good. Therefore, composi
tions containing the latter range of concentrations of
uranium, thorium and/ or plutonium constitute a preferred
phosphites, metal phosphates and metal halophosphates,
embodiment of this invention.
and wherein the amount of sulfur is at least about one
atom percent based on the amount of the sum of the sul
invention is present in the form of at least one constituent
tains, in addition, phosphorus compounds wherein the
The phosphorus employed in the compositions of this
fur and phosphorus atoms in the composition. Thus,
selected from the class consisting of oxides of phosphorus
and metal phosphates. A non-limiting example of ox
an embodiment of this invention is a nuclear reactor fuel
composition comprising (1) from about 0.01 to about 50
weight percent based on the total weight of said composi
ides of phosphorus is P205. Non-limiting examples of
10
tion of at least one element selected from the class con
the metal phosphates include the phosphates of the group
IA metals such as lithium orthophosphate, lithium di
hydrogen phosphate, sodium dihydrogen hypophosphate,
sodium orthophosphate, sodium monohydrogen phos
phate, sodium dihydrogenphosphate, sodium pyrophos~
phate, sodium metaphosphate, sodium tripolyphosphate,
sisting of uranium, thorium and plutonium wherein said
element is present in the form of at least one component
selected from the class consisting of oxides, halides and
oxyacid salts with (2) at least one member selected from
the class consisting of (a) sulfur, wherein said sulfur is
in the form of at least one entity selected from the class
consisting of oxides of sulfur, metal sulfates, metal sul~
Na5P3Om, sodium mono?uorophosphate, sodium hexa
?uorophosphate, potassium orthophosphate, potassium
monohydrogen phosphate, potassium dihydrogen phos
phate, potassium metaphosphate, potassium hexa?uoro
?tes, acids of sulphur and metal halosulfonates, (b) halo
gen, wherein said halogen is in the form of at least one 20 phosphate, rubidium metaphosphate, cesium metaphos
member selected from the class consisting of metal halides,
phate; the phosphates of the group IIA elements such as
metal halosulfonates and metal halophosphates, (c) phos
phorus, wherein said phosphorus is in the form of at
beryllium phosphate, magnesium phosphate, magnesium
hydrogen phosphate, magnesium metaphosphate, calcium
least one constituent selected from the class consisting of
phosphate, calcium monohydrogen phosphate, calcium
dihydrogen phosphate, calcium metaphosphate, strontium
phosphate, strontium acid phosphate, barium phosphate,
barium monohydrogen phosphate; the group IIIB phos
oxides of phosphorus, metal phosphates, metal phosphites
and metal halophosphates, wherein the amount of at least
one member selected from the class consisting of halogen
and sulfur is at least about one atom percent based on
phates such as lanthanum phosphate; the group IVB phos
the amount of the sum of said sulfur, halogen and phos
phates such as zirconium phosphate; the group VB phos
phorus atoms in said composition. Hence, the amount 30 phates such as vanadium phosphate; the group VIB phos
of sulfur and/or halogen in the composition based on
phates such as chromium phosphate, molybdenum meta
the total atom percent of sulfur, halogen and phosphorus
phosphate; the group VIIB phosphates such as manganese
can vary from about one atom percent to 100 atom per
orthophosphate, manganese monohydrogen orthophos
cent. At least about one atom percent of sulfur or halo
phate, manganese dihydrogen orthophosphate, manganic
orthophosphate, manganese pyrophosphate, manganic
gen is required in the composition in order to lower 35
the viscosity of the solution and thus provide a molten
metaphosphate; the group VIII metal phosphates such as
fuel composition which can be employed both as a fuel
ferric orthophosphate, ferric pyrophosphate, cobalt or
in the critical region of the reactor core and as a coolant
by circulating the solution through an external heat ex
changer.
40
thophosphate, nickel orthophosphate, nickel pyrophos
phate, platinum pyrophosphate; the group IB phosphates
Another embodiment of this invention is a fuel com
such as cupric orthophosphate, silver orthophosphate,
position in which the amount of sulfur based on the total
amount of sulfur and phosphorus is from about one atom
percent to about 99 atom percent. This provides a fuel
phate; the group IIB phosphates such as zinc orthophos
composition having a suitable viscosity for molten fuel
reactors.
Another embodiment of this invention is a
composition in which at least about 10 atom percent of
the sulfur present is in the form of alkali metal sulfur
silver monohydrogen orthophosphate, silver metaphos
phate, zinc dihydrogen orthophosphate, zinc pyrophos
phate, cadmium orthophosphate, cadmium dihydrogen
phosphate, mercuric orthophosphate; the group IIIA
phosphates such as aluminum orthophosphate, thallium
orthophosphate, thallium dihydrogen orthophosphate; the
containing compounds since then, not only is a suitably 50 group IVA phosphates such as stannous orthophosphate,
stannous monohydrogen orthophosphate, stannous dihy
low viscosity obtained but a lower melting point solution
drogen orthophosphate, stannous pyrophosphate, stannous
is provided which further enhances the attractiveness of
metaphosphate, lead orthophosphate, lead diorthophos
the solution as a nuclear reactor fuel composition. While
phate, lead mono orthophosphate, lead metaphosphate;
it is preferable to have at least about 10 atom percent
the
group VA phosphates such as bismuth orthophos
of the sulfur present in the form of alkali metal sulfates,
phates; the rare earth phosphates such as cerous ortho
it is especially preferred that the sulfur present in the
phosphate, cerous metaphosphate, samarium phosphate,
form of alkali metal sulfates or alkali metal pyrosulfates
gadolinium phosphate, etc.
range from about 25 to about 75 atom percent of the
In order to ensure as low a viscosity for the molten fuel
sulfur in the composition since then a higher degree of
?ssionable fuel material solubility is obtained at lower 60 composition as possible, it is preferable that at least
temperatures and at lower viscosities of the melt.
As stated hereinabove the amount of ?ssionable ma
terial in the fuel can vary from about 0.01 to about 50
weight percent based on the total weight of the compo
about 60 atom percent of the phosphorus, other than the
phosphorus present in the compounds containing ?ssion
sition. Compositions containing from about 0.1 to about
50 weight percent, however, are preferred in order to
able material, be present in the form of alkali metal
phosphorus-containing compounds or oxides of phos
phorus such as P205. This then constitutes a preferred
embodiment of this invention. It is especially preferred
more easily obtain the critical mass in the reactor core.
that at least 60 atom percent of the phosphorus, other
than the phosphorus present in the compounds contain
For still better performance, fuel compositions contain~
ing from about 1 to about 50 weight percent are preferred. 70 ing ?ssionable material, be in the form of alkali metal
However, since it is desirable to have as high a concentra
tion of ?ssionable material as possible in the reactor fuel
metaphosphate or P205 since then a greater reduction in
the viscosity of the molten composition is obtained.
Non-limiting examples of various fuel compositions
in order to obtain high fuel burn-up and greater economy
containing both phosphorus and sulfur and/or halogen
in the production of power, it is found that concentra
tions of the ?ssionable material of from about 10 to about 75 atoms therein are given in the following Table II.
3,063,923
TABLE II M
No.
Components
Weight
Atom
Parts
Percent
Percent
Percent
by
U, 'I‘h
S based
P based
Atom
weight
or Pu
on S
on S
and P
and P
Remarks
60 atom percent of the phosphorous is present in the form of
alkali metal meta phosphate.
Metal oxides other than oxides of uranium constitute 40 weight
percent of composition, excluding the weight of UaOa.
1 weight percent metal oxide based on weight of composition
excluding weight of UOzSO4.
10 atom percent of the S is present in the form of alkali metal
sulfates. Of the phosphorus present, 90 atom percent is in the
4
__________________ ..
90
form of alkali metal meta phosphate.
3
v
5
7
4
5..
3
...._
10
A"...
25
8
6..
m2.
.._
_.
.
90 atom percent of the sulfur is present as alkali metal sulfate.
._
_
_
7
3
1
3
60 atom percent of the phosphorus is present in the form of oxides
1,
1,
of phosphorus.
3
7
2. 6 ‘
Metal and metalloid oxides other than oxides of thorium con
126
13
stitute 40 weight percent of the composition excluding the
'
weight of Th0:.
-
45
4g
_
36
10
188
__________________ __ 1 Weight percent metal chloride based on the weight of the com
__________________ ._
12
________ -_
2
66
25
61
67
3
97
position excluding ThO(SO4) .
________ .
__________________ __ 60 atom percent of the alkali metal phosphates are present in the
__
form of alkali metal meta phosphates.
__________________ _.
73. 5
5
.
4
____________________________ __
_
22
4
Sm: (S 04) s.-14.-___ ThF4 ______ __
-_
3
32
24
UO2(NOs)2__
8.5
PuBra _____ __
3. 5
P205 ______ __
26. 5
_
v
__________________ __ 86 atom percent of the phosphorus 1s present in the form of P205
__________________ __
0f the sulfur, 93 atom percent is in the form of alkali metal
sulfates.
-
AlPO4 ____ __
_
Pb(P04)2---
____________________________ ._
Cd3(PO4)?-_-
37
MS 04 ..... __
40 weight percent of the composition, excluding ‘F110,, is com
posed of the metalloid oxide, S10].
' 60 atom percent oi the phosphorus is present in the form of oxides
of phosphorus.
woczaimqp
H
’
'
w
' 40 weight percent of the composition, excluding P110’, is com
posed of metal oxides other than PuOz.
I About 1 weight percent metal oxides in composition, based on
weight of composition other than P1101804.
a
3,063, 923
1l
12
TABLE II—Continued
No.
Components
21 ._._.
Weight
Atom
Atom
Parts
Percent
Percent
Percent
by
U, Th
S based
P based
weight
or Pu
on S
on S
and P
and P
70
Remarks
16 atom percent of the sulfur is present in the form of alkali metal
125
sulfur compounds.
5
5
4
22
22_____ ThF
t
32
14
6O atom percent of the phosphorus is present as alkali metal meta
phosphate. About 90 atom percent of the sulfur is present in
g 6
carom...
Cua(POi):.._
L
the form of an alkali metal sulfur compound.
31s
3
32
2
3
57
i3
24_____
40
33 weight percent of the composition, excluding Pu;(O0i)a, is
31;
in the form of the metalloid oxide $101.
20
As noted from the examples given hereinabove the
compositions can contain one or more metal or metalloid
501mm.
oxides in an amount equivalent up to about 40 weight
percent, based on the weight of the sulfur, the phosphorus
NO-
Composition
teclii‘slggila
mm, 6 0,
and the metal oxide compounds other than the com- 30
pounds of the uranium, thorium and/or plutonium.
32___ U0PM1>,o,,+31\1a1>0a _______________________________ __
The components employed ln the preparation of the
'
550
UF‘ Compositions
fuel composltlons in this invention are preferably anhy
drous.
However, hydrated components may be em
_
ployed in the preparation of the melts since such com
ponents are merely heated to a high enough temperature
for a period of time su?icient to drive off the Water of
33...
UF4+2PaOs+3NaPOs+2KrSzO1 ..................... ._
250
35 34W UF4+3P205+4NHP03+3K2S207 _____________________ __
250
Thorium Compmmd “mm-litmus
35.-.
hydration, leaving behind the vanhydrous counterpart.
Still other non-limiting examples of this invention are
as___ 'I‘ (s l):
illustrated in the following Table III.
40 39-“
TABLE III
The nuclear fuel compositions of this invention are
used in reactor cores and reactors heretofore known as
45 molten salt reactors and liquid-metal fuel reactors with
No_
Composition
cation
no modi?cation except for possible change in core di
ttempgr'g-
mensions in order to accommodiate the required critical
me’
'
U0 Com osmons
’
p
mass.
These reactors are described in full in a text
entitled “Fluid Fuel Reactors” by Lane, MacPherson and
50 Maslan, Part ‘II and Part 111, pages 567 et seq., 1958
l---' U0@+2P105+2HIS’O1------------------------------- --
25°
edition, published by Addison-Wesley Publishing Com
ZIII ggiiip’fp‘érifz?gf’dxj
588
pany, Inc., Reading Massachusetts, and in the references
4-~—~ U03+4N8P°3+2H2S101 ------ <-
200
contained therein.
2____ 38Zi§é§it§i$§2?5£é$9i
208
Table I ls used as a fuel in the Aircraft Reactor EX
275 55 periment reactor described in full in “Nuclear Science
321i: ggiiiiiigiiggggiig?igfd;"ziaaélglii"in?
U)
UOzSOi and UOzSzO1 Compositions
13___ Uo1soi+3NoP03 (35.4 weight percent in __________ __
14... UO2SO4+HHSOA+ZNEPOL_._
.
For example composition No. 4 in
am’
and Engineering,” vol. 2, pages 804-853 (1957). When
ggg
this fuel is used in the ARE reactor, criticality is readily
535
559
obtained vwith the excess reactivity controlled by control
rods. Good operation is obtained over long periods of
350
350
60 time.
The following non-limiting examples illustrate reactor
core loadings in whlch the reactor is of the molten salt
type described in detail in the text “Fluid Fuel Reactors,”
supra, pages 681-696. ‘In general, the reactor operates
65 with the fuel in a fused or molten state within the
reactor core, and when circulated there is a rise in
temperature of the fused fuel composition within the
23...
Uo2soi+llznsol+9Nais0l . . . . _ _ _ . . . . . . . .
. _ . .-
nolsol+suaroi __________________________ __
_____
24__. louois0i+7Na1>0a+3Na.P201+14Nais04-._
3UOzSO4+97K2SzO1 _ _ _ . _ _ _ _ _ _ _ _ _ _ _ _
.._...
. . . -_
l _ _ _ . _
_ _ _ ._
-
29___ uoi+zl>ioi+zxzsio1 ............................... -_
31." UO1+2P3O;+4.5NaPO; _____________________________ __
of
rorn
f
about
100
t
o
abou
t
600°
F.
’
althou
gh
smaller and greater rises in temperatures are permitted.
_
70
_
28"‘ MU0,304+glmazsm??umpO3 __________________________ __
U01 Compositions
core
The uranium used in the following examples is U—233.
-
-
-
.
When other lsotopes of uranlum are present, the crltlcal
mass is given in terms of the U-233 content. The
critical masses are as indicated. 'In the two-region sys
850
tem the core contains a uranium composition around
550 75 which is contained a two feet blanket of the thorium
3,033,923
13
composition indicated. The‘ core- is made of Inconel.
Further particulars are contained in the following ex
amples wherein the components of the compositions are
‘given in parts by weight.
Example I
A two-region reactor having a core diameter of 3.2
feet is operated on a core composition of 4.2 parts by
weight of UO2S2O7, 75.5 parts of RbHSO4, 14.4 parts
of CaSO4 and 5.9 parts of T125104. The amount of
uranium in this composition which is in the form of
U—233 is 2.2 weight percent. Of the sulfur in the com
position, 75 atom percent is present in the form of an
‘alkali metal sulfate, a rubidium acid sulfate in this case.
An amount of composition su?icient to provide a critical
U—233 mass of 31 kilograms is employed. The two-foot
‘blanket surrounding the core is made up of 11.5 parts
tion having a composition comprising 34 parts by weight
of T110504, 64 parts Na2PO3 and 38 parts P205. The
amount of thorium is 17 weight percent based on the
total weight of the blanket solution. The amount of
sulfur present, based on the total amount of sulfur and
phosphorus is 8.1 atom percent. The amount of blanket
solution employed is sufficient to provide 1378 kilograms
of thorium.
' The reactor of Example IV is also operated satisfac
torily on composition No. 13 of Table III.
Example V
A two-region reactor is operated with a core having a
diameter of 1.6 feet. The core contains a solution having
a composition composed of 56 parts by weight of U03,
31 parts NaPO3, 28 parts P205 and 44 parts N32S207
The uranium concentration is 29.2 weight percent based
on the total Weight of the composition with the solution
present in an amount su?icient to give a U—233 critical
of Na2S2Oq and 0.9 part of Na2O. The amount of ma
‘terial in the blanket is sui?cient to provide 1445 kilo 20 mass of 50 kilograms. The amount of sulfur present
in the composition based on the total amount of sulfur
grams of thorium. The composition contains 10.1 per
and phosphorus present is about 36.4 atom percent. The
cent of thorium by weight and has 90 atom percent
blanket solution has a thorium content of 10.1 weight
sulfur based on the amount of sulfur and phosphorus
percent based on the total weight of the thorium solution
present, together with 1 weight percent of the metal
of ThOZ, 3.5 parts of S03, 9 parts of Na4P2O7, 75.1 parts
oxide, Na2O, based on the weight of components other
than the thorium oxide. The reactor is operated satis
factorily at temperatures ranging from that of the molten
‘state at the melting point to about 900° C.
and has a composition consisting essentially of 13.5 parts
KPO3,’ 69 parts K3PO4, 5 parts S03’ 4 parts Na2SO4, 16
parts NaHSO4, 4 parts SrSO4 and 3 parts Sm2(S04)3.
the core containing a critical mass of U—233 in the form
of solution No. 2 of Table I and a blanket solution of
composition No. 10 in Table I. Also, a two-region re
by weight of ThO2, 30.6 parts NaPO3, 28.4 parts P205
and 44.4 parts NaZSZOq. The amount of thorium solu
tion is su?icient to provide 729 kilograms of thorium.
The amount of sulfur in the solution based on the total
Example II
30 amount of sulfur and'phosphorus present is about 36.4
A two-region reactor having a core diameter of 3 feet
atom percent.
is operated with a core solution'composition described
In like manner, the reactor of Example V is operated
in Example I in an amount su?‘icient to provide a critical
with composition No. 7 of Table I in the core and a
U—233 mass of 25 kilograms. The blanket region sur
blanket region solution having the composition of N0. 15
rounding the core is ?lled with a composition consisting
in Table I.
essentially of 54 parts by weight of ThOSO4, 59 parts
In like manner, a two-region reactor is operated with
The amount of the blanket solution is suf?cient to pro
vide 2238 kilograms of thorium. The thorium is present
in an amount equivalent to '17 weight percent based on
the total weight of the composition and the phosphorus
to-sulfur atomic ratio is 2:1, equivalent to 66 atom per
cent phosphorus based on the phosphorus and sulfur
present. Of the sulfur in the composition, 39 atom
percent is present in the form of alkali metal sulfates.
‘The reactor operates satisfactorily at temperatures above
the melting points of the compositions.
Example III
actor is operated on a core solution containing a critical
mass of U—233 in the form of solution No. 1 in Table I
and a blanket solution having composition No. 9 in
Table I.
The following examples illustrate a single region fused
salt reactor in which the reactor is essentially the same
as that described for the two-region reactor with the
modi?cation that the core has no blanket. That is, the
fuel is contained all within a single region. The follow
ing non-limiting examples will further illustrate such re
50 actor core compositions.
' A two-region‘reactor having a core diameter of 1.7
Example
feet is operated with a core solution of 36 parts by weight '
of UO2SO4, 57 parts NaPO3, 20 parts Na2O, 10 parts
M00 and 8 parts Fe2O3. The amount of core solution
is suf?cient to-provide a U—233 critical mass of 37 kilo
grams. ‘The concentration of the uranium is 17.7 weight
percent based on the total weight of the solution and the
amount of sulfur is about 15.2 atom percent based on
the total number of atoms of sulfur and phosphorus pres
ent. The amount of metal oxides present is about 40
weight percent based on the weight of the metal oxides
and sodium metaphosphate present. The blanket solu
tion is the same as that described in Example I and is
present in an amount su?icient to provide 761 kilograms
of thorium.
Example IV
A two-region reactor is operated with a core having a
diameter of 1.8 feet containing a solution of 36 parts by
'
VI
A single region reactor having a core diameter of 5.2
feet is operated with a core solution of 1.2 parts by
‘weight U02, 8.2 parts ThO2, 80.6 parts Na2SO4 and 10
parts ZnSO4. The amount of solution -is sui?cient to
give a U—_233 critical mass of 63 kilograms and a thorium
content of 431 kilograms. The U—233 is present in an
amount of 1 weight percent and the thorium is present in
an amount of 7.2 weight percent based on the total
weight of the composition. Ninety atom percent of the
sulfur in the solution is present in the form of an alkali
metal sulfate.
‘
Example VII
VA single region reactor is operated with a core having
a diameter of 1.9 feet ?lled with a fuel solution having
a composition of 10.8 parts by weight UO-Z, 6.6 parts
ThSO4, 5.8 parts NaZSZOq and 76.8 parts CuSO4. The
weight of UOZSO4, 64 parts NaPO3 and 31 parts P205. 70 amount of solution is su?icient to provide a U—233 criti
cal mass of 27 kilograms and a thorium content of 14
The amount of uranium is _17.7 weight percent based
kilograms. The concentration of U—233 is 9.5 Weight
percent and that of thorium is 4.7 weight percent based
on the total weight of the composition. Ten atom per
cent of the total sulfur in the composition is present in
75
'the form of alkali metal sulfates.
‘44 kilograms. The blanket region is ?lled with a solu
on the total weight of the composition. The amount of
sulfur based on the total amount of phosphorus and
sulfur present is 9.1 atom percent. The amount of core
solution is sui?cient to provide a critical U—233 mass of
3,063,923
15
Example VIII
16
When the fuel is circulated ‘for the removal of heat, a
4 or 5 foot diameter core provides a 500 mw. reactor of
A single region reactor is operated with ‘the core hav
ing a diameter of ‘2.1 feet containing a solution having
the single region type.
the composition consisting essentially of 10.4 parts by
weight U03, 10.2 parts T1102, 32.2 parts NaPO3, 40.8
parts Zn3(PO4)2, 0.65 part Li2SO4 and 5.75 parts CaS2O7.
tionary is operated as a fast reactor of 100 to 200 mw.
The amount of solution is sut?cient to provide a U-233
critical mass of 36 kilograms and a thorium content of
36 kilograms. The concentration of U-233 is 9 weight
percent and the concentration of thorium is 9 weight per
cent based on the total weight of the composition. The
amount of sulfur in the fuel solution is about 10 atom
percent based on the total amount of sulfur and phos
The two-region reactors with the melt remaining sta
power using a melt of 10 weight percent uranium or
greater in a 2-foot core. When the reactor is operated as
an epithermal reactor of high power of the order of 500
mw. or higher, the uranium concentration in the fuel is
about 2 weight percent orless and the fuel is circulated
through the core which has a diameter of about 5 feet.
The term “?ssionable material,” referred to in this
writing, is uranium, thorium or plutonium. The term in
cludes natural uranium. In other words, no distinction
phorus present. Of the sulfur in the solution, 10 atom
percent is present in the form of alkali metal sulfates. 15 is made between the various isotopes of uranium or of
thorium or of plutonium. References to uranium in this
‘Of the ‘phosphorus in the solution, about 60 atom percent
writing may be taken to mean natural uranium, unless
is present in the form of alkali metal phosphates.
Example IX
The reactor of Example VIII is operated on a core solu
tion having a composition of 10.4 parts by weight U03,
10.2 parts ThO2, 78.2 parts KPO3 and 1.2 parts Rb2S2O-7.
The critical mass of U—233 is 36 kilograms and the tho
rium content is also 36 kilograms. The sulfur content is
1 atom percent based on the total amount of sulfur and
phosphorus present.
Example X
otherwise speci?ed. The phosphate compounds described
in this writing include polyphosphates such as, for exam
ple, Na4P2O7. Also, the oxyacid salts referred to herein
are salts of oxygenated anions as, for example, UO2SO4,
Na2UO4, NazUzOq, NazPuzOq, etc. The term “metal ox
ides,” whenever used hereinabove, includes ‘rn'e’talloid ox
ides such as SiOz, etc.
The examples to the use of speci?c fuel compositions
in the fused salt type of reactors and in the liquid metal
fuel reactor type are by way of illustration only and not
to be construed as limitations on the compositions of this
invention. Reactors are operated employing all the fuels
A single region reactor is operated with a core having
a diameter of 1.6 feet containing a solution of 26.4 parts 30 disclosed in Tables I, II and III and elsewhere throughout
‘by weight UO2SO4, 4.8 parts ThO2, .3 part LiPO3, 59.6
Eparts K2804 and 8.9 parts 321804. The amount of solu
Plion is sufficient to give a U-233 critical mass of 29 kilo
.‘grams and a thorium content of 7 kilograms. The U-233
concentration is 17 weight percent and that of thorium is
‘4.2 weight percent based on the total weight of the compo
‘sition. The sulfur content of the solution is 99 atom per
"cent based on the total amount of sulfur and phosphorus
present.
Of the sulfur in the solution, 90 atom percent is
this writing. The examples and descriptions given above
are merely illustrative and not restrictive of the present
invention. Variations of the compositions may be made
within the scope of the invention by those familiar with
nuclear fuel technology and the operation of nuclear
reactors. Therefore, the present invention should be
limited only as indicated by the appended claims.
I claim:
1. A fused nuclear reactor fuel composition for utiliza
40 tion in molten form, consisting essentially of
present in the form of alkali metal sulfate.
(1) from about 0.01 'to about 50 wt. percent based on
As in Example X, a single region reactor is operated on
the total weight of said composition of at least one
a solution having the composition of No. 22 in Table II.
element selected from the class consisting of ura
In like manner, a single region reactor is operated on
nium, thorium, and plutonium, wherein said element
composition No. 12 in Table I which contains, in addition,
is present in the form of at least one component se
1 weight percent sodium ?uosulfonate and 1 weight per
lected from the class consisting of oxides and salts of
cent sodium mono?uorophosphate.
Example XI
A reactor of the design of the Liquid Metal Fuel
Reactor (LMFR), described in the “Fluid Fuel Reactors” 50
text, supra, and having the design speci?cations given on
page 887 of the text, is operated on a core solution con
taining 0.1 weight percent U-233 in the form of UO2SO4
together with Na2SO4 and ZnSO, in the molar ratio of
340-2. The blanket contains a composition having 10 55
‘weight percent thorium in the form of ThOz together
l'with N'aPO3 and Na2S2O'q in the molar ratio of 3-to-5.
The mass of U-233 in the system is about 330 kilograms
and the ‘mass of thorium is about 28,000 kilograms. The
reactor is satisfactorily operated at a reactor core tem 60
perature of substantially 500° C.
The compositions of this invention provide an attrac
tive fuel for homogeneous reactors, thus avoiding expen
sive fuel element fabrication and permitting higher fuel
burn-up, as well as allowing removal of some ?ssion prod 65
uct poisons during reactor operation as described in the
“Fluid Fuel Reactors” text. The reactors operate at low
pressures and favorable temperatures. For example, it
oxygenated anions, and
(2) the remainder at least one member selected from
the class consisting of
(a) sulfur, wherein said sulfur is in the form of at
least one entity selected from the class consist
ing of oxides of sulfur, non-?ssionable metal
sul?tes and halosulfonates, and acids of sulfur,
wherein at least 10 atom percent of said sulfur
is present in the form of alkali metal-containing
sulfur entities, and
(b) phosphorus, wherein said phosphorus is in the
form of at least one constituent selected from
the class consisting of oxides of phosphorus, and
non-?ssionable metal phosphates, phosphites
and halophosphates, wherein at least about 60
atom percent of said phosphorus is present in the
form of at least one constituent selected from the
class consisting of oxides of phosphorus and
alkali metal metaphosphates.
2. A fused nuclear reactor fuel composition for uti
lization in molten form, consisting essentially of
is seen that the fuel compositions remain molten at a tem
perature of as low as 225° C. as shown in Table III. The
(1) from about 0.01 to about 50 wt. percent based on
the total weight of said composition of at least one
fuel compositions readily remain ?uid at temperatures
above 400° C. The solutions are highly resistant to radia
element selected from the class consisting of uranium,
thorium, and plutonium, wherein said element is
tion damage and are not highly corrosive to Inconel and
‘steel containers. Zircalloy 2, Hastelloy and zirconium
present in the form of at least one component
selected from the class consisting of oxides and salts
carbide are not noticeably corroded by the compositions.
of oxygenated anions,
3,063,923
18
17
(2) sulfur, wherein said sulfur is in the form of at
least one entity selected from the class consisting of
oxides of sulfur, non-?ssionable metal sul?tes and
halosulfonates, and acids of sulfur, wherein at least
10 atom percent of said sulfur is present in the form
of alkali metal-containing sulfur entities, and
9. The composition of claim 8 wherein said elements
in (1) are in the form of oxides and said sulfur is in the
(3) phosphorous, wherein said phosphorus is in the
11. A fused nuclear reactor fuel composition for utiliza
tion in molten form, consisting essentially of
form of alkali metal-containing sulfur components.
10. The composition of claim 9 wherein the said oxide
is U03 and comprises 10-36 wt. percent of the fuel com
position.
form of at least one constituent selected from the
class consisting of oxides of phosphorus, and non
?ssionable metal phosphates, phosphites and halo 10
phosphates, wherein at least about 60 atom percent
‘of said phosphorus is present in the form of at least
element selected from the class consisting of uranium,
thorium, and plutonium, wherein said element is
present in the form of at least one component
one constituent selected from the class consisting of
selected from the class consisting of oxides and salts
oxides of phosphorus and alkali metal metaphos
phates.
(1) from about 0.01 to about 50 wt. percent based on
the total weight of said composition of at least one
15
3. The composition of claim 2 wherein said elements in
(l) are in the form of oxides.
4. A fused reactor fuel composition for use in molten
of oxygenated anions, and
(2) the remainder phosphorus, wherein said phos
phorus is in the form of at least one constituent
selected from the class consisting of oxides of phos
form consisting essentially of XPO3, X28207, U03 and
phorus, and non-?ssionable metal phosphates, phos
P205, wherein X is an alkali metal, and wherein said 20
composition consists of 10-36 wt. percent U03.
phites and halo-phosphates, wherein at least about 60
atom percent of said phosphorus is present in the
5. A fused reactor fuel composition for use in molten
form of at least one constituent selected from the
class consisting of oxides of phosphorus and alkali
metal metaphosphates.
X2804, wherein X is an alkali metal, and wherein said
12. The composition of claim 11 wherein the compo
composition consists of 10-36 wt. percent U03.
25
nents in (1) are in the form of oxides.
6. A fused reactor fuel composition for use in molten
13. The composition of claim 12 wherein the oxide
form consisting essentially of X1903 and UO2SO4, wherein
components consist of about 10—36 wt. percent of the
X is an alkali metal.
fuel composition and said phosphorus is present in the
7. A fused reactor fuel composition for use in molten
30 form of alkali metal phosphates.
form consisting essentially of, by molecular formula:
form consisting essentially of U03, XPO3, XP2O7, and
8. A fused nuclear reactor fuel composition for utiliza
tion in molten form, consisting essentially of
(1) from about 0.01 to about 50 wt. percent based on 35
the total weight of said composition of at least one
element selected from the class consisting of uranium,
thorium, and plutonium, wherein said element is
present in the form of at least one component
selected from the class consisting of oxides and salts 40
of oxygenated anions, and
(2) the remainder sulfur, wherein said sulfur is in the
form of at least one entity selected from the class
consisting of oxides of sulfur, non-?ssionable metal
sul?tes and halosulfonates, and acids of sulfur, 45
wherein at least 10 atom percent of said sulfur is
present in the form of alkali metal-containing sulfur
entities.
References Cited in the ?le of this patent
UNITED STATES PATENTS
2,741,593
2,816,042
2,818,605
2,820,753
2,824,784
2,835,608
2,837,476
2,908,621
2,929,767
2,939,803
Metcalf et a1 __________ __ Apr. 10,
Hamilton ____________ __ Dec. 10,
Miller ________________ __ Jan. 7,
Miller et al. __________ __ Jan. 21,
Hansen ______________ __ Feb. 25,
Kanter ______________ __ May 20,
Busey _______________ __ June 3,
Segre et al. __________ __ Oct. 13,
Hammond et al._ _____ __ Mar. 22,
1956
1957
1958
1958
1958
1958
1958
1959
1960
Steele et al. __________ __ June 7, 1960
OTHER REFERENCES
Nuclear Science and Engineering, November 1957, pp.
826-853.
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