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IAEA-TECDOC-515
F I S S I O N M O L Y B D E N U M
F O R
M E D I C A L
U S E
PROCEEDINGS
OF A
TECHNICAL COMMITTEE MEETING
ORGANIZED BY THE
INTERNATIONAL ATOMIC ENERGY AGENCY
AND HELD
IN
KARLSRUHE, 13-16 OCTOBER 1987
ATECHNICAL
DOCUMENT
ISSUED BY THE
INTERNATIONAL ATOMIC
ENERGY AGENCY
VIENNA,
1989
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FISSION MOLYBDENUM
FOR MEDICAL USE
IAEA,
VIENNA,
1989
IAEA-TECDOC-515
ISSN 1011-4289
Printed
by the IAEA in Austria
June
1989
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FOREWORD
Because of its
favourable
physical and chemical properties,
T̂c
is
today the radionuclide of
choice
for
routine
diagnostic
nuclear
medicine. The
A n
parent radionuclide
Mo is
produced mainly
by the
nuclear fission
of
U. Small
amounts
are produced by the neutron activation method,
however, current
generator technologies
are not yet fully
developed
to
utilize
the so-called n,y Mo" in medium or
large production
scale.
There are several countries, particularly those with sizable
local
Q
Q
demand, seriously considering
the possibility to locally
produce
Mo
through the
fission
route.
In view
that
the required technology is highly
sophisticated and that the necessary capital investment is
very high,
some
Member States have requested the co-operation of the Agency for technical
advice.
In
response
to the
growing interest
in this
matter,
and in
order
to
provide some
guidelines both
to the
Agency
and to interested Member
States,
the
IAEA convened
the Technical
Committee Meeting
on
"Fission
Molybdenum for
Medical Use .
The
report
includes
an
assessment
of the
current
target and
process technologies, problems associated with radioactive waste disposal as
well
as views on economical factors and proliferation
concerns.
Also included
are all the
contributions
presented at the meeting by individual participating
countries.
The Agency wishes to thank all the scientists and institutions who
contributed
to the meeting with their
ideas
and scientific papers.
The officer of the
IAEA
responsible for the
meeting
was H. Vera Ruiz of
the Division of
Physical
and
Chemical Sciences.
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P L E A S E
B E
A W A R E T H A T
A L L O F T H E
M I S S I N G
P A G E S IN
T H I S
D O C U M E N T
W E R E
O R IG I N A L L Y B L A N K
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EDITORIAL NOTE
In preparing this material for the press s t f f
of
th e International
Atomic
Energy Agency have
mounted and paginated the original
manuscripts
as submitted by the authors and given some
attention
to the presentation.
The views expressed
in the
papers,
th e
statements
made and the general style
adopted
are the
responsibility of the named
authors.
The views do not
necessarily
reflect those of the governments
of th e
Member
States or organizations
under
whose
auspices
th e manuscripts were produced.
The
use in
this
book of pa rticular designations of countries or
territories does
not imply an y
judgement by the
publisher,
the IAEA, as to the
legal
status o f such countries or territories, o f their
authorities an d institutions or of the delimitation of their boundaries.
The
mention of
specific
companies or of their
products
or
brand
names does not imply an y
endorsement
or recommendation on the part of the IAEA.
Authors
are
themselves
responsible for
obtaining
the necessary
permission
to
reproduce
copyright
ma terial from
other sources.
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CONTENTS
SUMMARY
REPORT
1.
I N T R O D U C T I O N
........................................................................................
7
2.
S C O P E OF THE M E E T IN G
..........................................................................
8
3.
T A R G E T
T E C HN O L O G Y
D E V E L O P M E N T .....................................................
9
4. C U R R E N T P R O C E S S
T E C H N O L O G Y
............................................................ 12
5. P R O B L E M S A S S O C IA T E D W I TH W A S T E DIS P O S A L ....................................... 12
6.
E C O N O M I C F A C T O R S ................................................................................ 13
7. P R O L I F E R A T I O N C O N C E R N S ..................................................................... 15
7.1.
Highly
enriched uranium
contained
in fission M o
production
targets ................. 15
7.2. Plutonium produced in fission M o
product ion
............................................. 15
7.3. U r a n i u m recycling ................................................................................. 15
8.
S A F E G U A R D S ...........................................................................................
16
9.
Q U A L I T Y A S S U R A N C E
A N D
Q U A L I TY
C O N T R O L
........................................
1 6
10. P O S S I B IL I T IE S F O R T E C H N O L O G Y
T R A N S F E R .............................................
17
1 1 . S U M M A R Y O F C O N C L U S I O N S A N D
R E C O M M E N D A T IO N S
............................ 19
PAPERS PRESENTED
AT THE MEETING
Operation
of the installation for fission M o production in Argentina .............................. 23
R. O. M arqués, P . R. Cristini , H. F ernandez, D . M artiale
Development
of the M o process at
C R N L ..............................................................
35
K.A. Burrill R.J. Harrison
Product ion techniques
of
fission
M o ...................................................................... 47
A.A.
Sameh,
H.J. Ache
Production of
fission
M o by processing irradiated natural uranium targets ....................... 65
O . Hladik, G . Bernhardt, W . Boessert, R. Münze
Research
a nd development of M o production
technology
in J a p a n ................................. 83
H. Kudo, N. Yamabayashi, A. Iguchi, E. Shikata
Preliminary investigations for technology assessment of M o production
from
L E U targets . .. 99
G.F. Vandegrifi,
D.J. Chaiko, R.R.
Heinrich,
E.T. Kucera K.J. Jensen D.S. Poa
R .
Varma,
D.R.
Vissers
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Cont inuing
investigations for technology assess m ent of M o
product ion
from L E U t a r g e t s
....
115
G.F.
Vandegrifi, J.D. Kwok, S.L. Marshall, D .R , Vissers, J.E. Matos
Product ion of
fission Mo,
1 3 I
I and
133
X e
................................................................
129
J. Salacz
Irradiation
of
235
U in the
Osi r i s reactor
for the production of
M o,
13 1
I
a nd
l3 3
X e
radioisotopes
..................................................................................................
133
L .
Marchand
I r rad iat ion
of
235
U a t t h e B R 2 reactor for the
product ion
of M o,
I 3 I
I a nd
133
X e
radioisotopes. Short presenta t ion of the DGR
loop ...................................................
137
J.M.
Baugnet, G. Blondeel
I r rad iat ion of
235
U
in the HFR Petten for the
production
of M o,
13 1
I a nd
133
X e
radioisotopes ..................................................................................................
141
J. Konrad
Irradiat ion
of
235
U in the Siloé
reactor
for the production of M o,
I 31
I a nd
133
Xe
radioisotopes .................................................................................................. 143
/. Gallier
Reprocessing of
irradiated
235
U
for the
production
of
M o,
I 31
I
a nd
13 3
X e
radioisotopes
....... 149
/. Salacz
L i s t
of
Participants
............................................................................................. 155
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SUMMARY REPORT
1.
INTRODUCTION
Technetium-99m
is today the most widely used radionuclide in modern
diagnostic
nuclear medicine; very likely this will remain so for the
foreseeable
future.
This
is
mainly because
of its favourable nuclear
properties
and the
fact
that it was possible to
produce compact,
practical and transportable
TCc-
Mo generator systems, providing
significant amounts of ^rc to
users
far removed from the production
centres.
The
ever increasing
demand for
this radionuclide, both
in
developed
and
developing countries, may call for a greater production capacity and
availability, particularly in the
developing
countries,
many
of which
currently
operate
low and medium power nuclear research reactors.
235
Currently, the nuclear fission of U is the preferred method of
99
producing high specific activity Mo suitable for the preparation of
99
Chromatographie
generators. The drawback of the fission Mo
technology,
at least from the view-point of a developing country, is the
high
capital
investment and the relatively sophisticated
technology
required.
Inspite of the above, there are
several countries
with
sizeable nuclear medicine communities
seriously considering
the
possibility
of
introducing this
technology to reliably meet the
local
demand
of Tc.
99
Most of the
present fission
Mo technologies make use of highly
235
enriched U
(HEU)
as
Al-U
alloys or UO in a variety of target
designs, and the corresponding chemical separation processes have
been
developed
accordingly.
However, there are indications
that
the
availability of HEU
targets
may be restricted in the
future
and that new
or modified target technologies and separation methods have to be
99
99m_
investigated to ensure a high quality and
economical
Mo/ Tc
product
when using
low enriched
target materials
(LEU).
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2.
SCOPE
OF THE
MEETING
99
Countries wishing to set up
production
plants for
fission
Ho to
meet
ever
increasing
national
demands
of Tc for medical purposes,
should
seriously
and timely
take
into
account
the desirability of
using
low
enriched uranium
in this
process.
In this regard, the Agency should
continue
to play an active role in
facilitating
an exchange of
information
and ultimately an appropriate
transfer
of technology
between
developed
and developing
Member States
by
organizing
scientific
meetings
and
through
its
Technical Co-operation Programme.
The meeting was held at the Nuclear Research Centre of Karlsruhe,
Federal
Republic of
Germany,
from 13 to 16 October
1987,
and was
attended by
eleven specialists from
6
Member
States. All
papers
presented
at the
meeting
are included at the end of the
report.
In particular, the participants
were
asked to:
99
review the
known
current production technologies of fission Mo
for medical use including target technology, post
irradiation
chemical processing,
waste
disposal,
recycling of target
material
and reactor
irradiation
practices;
- discuss and assess the feasibility of substituting low enriched
uranium
for
highly enriched uranium
in
targets,
particularly
with
regard to new target materials and technology
(i.e.
high density
uranium-suicide
dispersions and
uranium
metal
films), purity
of
99
the Mo product, radioactive
waste
and
economics
of the process;
assess the
feasibility
of transfering this technology
from
developed to
developing countries
and
identify
possible bottle
necks
and problem areas that may
hinder
this technology
transfer;
and
identify
and define concrete
future lines
of activity where the
Agency's
efforts would have the greatest impact and significance.
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3.
TARGET TECHNOLOGY DEVELOPMENT
99
Most of the world's Mo is produced from the following three
target
geometries
(1) ÜO-
films
on the
inside walls
of stainless steel cylinders,
(2)
Uranium-aluminide alloy
extruded
into aluminium
clad
rods,
and
(3) Uranium aluminium dispersed in an aluminium matrix and pressed
between aluminium plates.
99
The first design is unique to Mo production; the second and third
designs are fabricated in the same manner as fuel for nuclear research
and
test
reactors.
235
Conversion of present HEU (~ 93% U) targets to those using LEU
235
(£ 20% U) requires a 5-6 fold increase in
total
uranium content to
99
produce irradiation yields
of Mo
equivalent
to
current
HEU
targets.
The
incorporation
of
this larger concentration
of
uranium
in
current
target geometries will
require modifications of the fuel composition.
In the case of HEU-oxide-film
targets,
research
at Argonne
National
Laboratory (AND
has been
directed
to the development of LEU metal films
which
can directly
replace
the U0
?
films
used
in current
target
designs.
It is
possible
to
place uranium
films on the
inside wall
of
cylindrical targets by either
loading
uranium metal foils or
electrodepositing
uranium
metal. The work at ANL has
concentrated
on
development of the electrodeposition technique.
99
Uranium
metal
targets for fission Mo production
have
several
advantages
over
U0
2
targets.
For
example, uranium
metal is
about
twice
as
dense
as
U0_,
ts thermal
conductivity
is an
order
of
magnitude higher
than that of
UO«,
and its plating
efficiency from
LiCl-KCl-UCl
3
molten salt melts is 100% vs. 20% for the UO
deposition process. The principal disadvantages of using
electrodeposited
uranium metal
targets
are
that
(1) they
must
be
prepared from molten salt
systems
at high temperatures (~ 450 C) in
an
inert
atmosphere,
and (2) the deposit
morphology
tends to be
dendritic.
While the higher
conductivity
and density
make
uranium metal
targets appear
quite promising, heat management and
safety issues
need
to
be
thoroughly analyzed.
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Experiments
performed
on simulated LEU
targets
have shown
that
(1) well-bonded
dendrite-free uranium metal
films can be bonded to
nickel-plated
stainless
steel or zircalory and (2) it is likely that LEU
targets
can be
processed using
the current
techniques
for HEU oxide
targets, with no significant changes. Uranium
metal
can be easily
dissolved and the higher amounts of uranium in the target will affect
99
neither Mo
yield
nor its purity. It is expected that the higher
amounts of transuranic (TRU)
elements
produced by the irradiation of LEU
will
be
handled easily
by current
processing steps.
The development of
U
3
s
i
?
and U Si fuels has made
core
conversion
from HEU to LEU possible in most research and test reactors currently
99
using
U-A1 alloy or uranium aluminide fuels. For Mo production
targets containing HEU alloy or aluminide
fuel,
the use of
replacement
of targets
containing LEU suicide fuel and the
same
target geometry
99
would retain current
irradiation
yields of Mo. Because these
targets will be fabricated in the same
manner
as reactor fuels,
their
ability
to be
fabricated
will be
assured
and difficulties in
licensing
will
be
minimized.
However, because of (1) the
different chemical forms
of
uranium
(e.g.,
U Si vs UA1 ) and (2) the need for harder
« 5 X X
cladding (e.g.,
Al 6061,
AlMg
or
AG3NE
aluminium alloys vs
pure
aluminium),
modifications in the current commercial chemical processes
99
for
Mo
recovery
will
be
necessary.
Although it is clear
that
processes can be
modified and/or
developed for LEU
silicide
targets,
there are,
however,
serious
concerns
that these developments will be
extremely
difficult
to integrate into ongoing production facilities
without disruption of
production schedules.
The Chalk
River Nuclear Laboratories (CRNL)
has performed
cold
and hot
testing of the ability of
their current
processing method to handle LEU
silicide
targets
that were
fabricated
using
materials and a
geometry
compatible with the
fabrication
method for LEU fuel rods. These tests
have
shown that
the current process method cannot be
used
directly to
process
LEU
silicide targets.
Two
problems were
discovered:
(1) A silicate precipitate from the
acid
dissolution of the targets was
finely
divided and difficult to
filter,
and plugged the
alumina
column
during processing.
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(2) This precipitate adsorbs Mo and holds it against elution from the
column. (This
problem
was not evident in cold
laboratory
tests but
was noticed in hot
testing using
an actual
full-size target.)
Tests at ANL, using simulated
targets,
have shown
that process
modifications can be made to the alkaline dissolution process to
contend
with
problems
developed from the use of suicide
fuels.
Tests
with
slightly irradiated targets are planned in early
1988.
New target designs that will not require
changes
in
current
processing
methods, have
a
great
appeal, even though
their fabrication
is expected
to be
more
expensive and licensing more
difficult.
Some alternative target designs
of
this
type
have
been
addressed
at
CRNL.
These
designs
include U
metal,
UO , U-A1 alloy, U
dispersed
in
aluminium, UO
dispersed
in aluminium, and other combinations.
Because UO is
economically attractive
due to
ease
of
preparation,
its
use in an aluminium
dispersion
has
been
explored to the
point
of
fabrication of full-size targets and cold
laboratory
testing. This
target
was fabricated by extruding a 3 m rod of UO
dispersed
in
aluminium at 60 wt % U. The extrusion required a large press and UO
was not uniformly
dispersed
throughout the rod. The rod was clad
with
pure
aluminium.
It was
then
cut into target
lengths
and processed in
99
the
laboratory
by
dissolving,
adding tracer Mo, and
processed
by an
alumina column. Difficulties with fabrication of the UO /Al rod may
be
solvable.
However, other target
compositions
continue to be
explored, including those made separate from reactor fuel fabrication.
99
In
conclusion,
LEU
targets
for Mo can be
fabricated
to
give yields
typically of current HEU targets. It is likely that
changes
in target
design and/or processing
will
be
necessary
for this
conversion.
The
economical impact
of
this
conversion has to be assessed.
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4. CURRENT PROCESS TECHNOLOGY
99
Six papers
were
presented on different process technologies of Mo.
R. Marques (Argentina),
A.
Samen (FRG)
and C.
Fallals (Belgium) reported
on results of processes based on the irradiation of highly enriched
14 2
(>90%
U-235)
targets in several High Flux Reactors (* > 10
n/cm
s)
and alkaline dissolution of different U-A1 targets. These processes
differ
mainly in the subsequent
purifications steps
of the
crude
99
Mo.
K.A. Burrill (Canada),
R.
Münze (GDR)
and H.
Kudo (Japan)
99
described
Mo
production
processes that use acidic
(HNO
)
dissolution. A slower rate of dissolution has been occasionally
observed in the GDR and Canadian processes. Limited
data
indicate that
this may be
correlated with
higher
burn-up. During
routine
production,
GDR personnel have experienced 20-50% lower
yields
because
of the
formation of a gelatinous precipitate arising
from
the presence of
silicon in the
cladding.
Whereas the Canadian process
starts with
highly enriched targets, the
GDR process uses medium enriched U-Al-targets (fuel elements of the
research
reactor, 36%
enriched). Kudo reported
on a method
based
on
2.6% enriched U0
?
pellets. All of these processes include separation
133 131
of Xe. In some cases I is separated as well.
All
processes discussed
during
the meeting have been demonstrated to
99
supply
Mo of a suffic
generators for medical use.
99
supply Mo of a
sufficiently
high
quality
for preparing column
5.
PROBLEMS ASSOCIATED WITH WASTE DISPOSAL
99
Processing highly enriched targets for Mo production generates
radioactive wastes which must be treated and disposed of in
environmentally acceptable ways.
The
wastes
will be generated as
solids,
liquids, and/or gases, and
will
include
material in the
low, medium,
and
high
radioactive
level
classifications.
Initial treatment
of the
wastes
is usually required at
the
production
site, prior to short or long term storage. The treatment
required
is
dictated
by
both
the form of the
waste
and its
activity
level.
This technology
is
established,
and
generally
available.
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The heavily shielded
process
and
interim storage facilities must
obviously
be built
on-site,
but the sophisticated equipment
required
for
them
would
generally have to be bought
off-shore.
Storage facilities may or may not need to be
constructed,
depending upon
the physical and
political availability
of
off-shore space.
In any event, an adequate
infrastructure
is required to transfer waste
from
the
fuel processing facility
to the waste
treatment
facility (if
not one and the
same),
and the treated
waste
to storage.
Trained
operating crews, and support personnel (maintenance, analytical,
accounting, safety, security, e t c )
are required for all facilities. In
addition, an
independent regulatory
body is
required,
to
review,
license, and monitor all
phases
of the operation.
6. ECONOMIC FACTORS
99
At
present the
world's supply
of Mo
comes
mainly from commercial
sources. In
Eastern
Europe, the German Democratic Republic is the
only
known
manufacturer with a capability of 1000
Ci/week.
Medi-Physics
(USA),
IRE (Belgium) and
AECL
(Canada)
are the other major
suppliers
in
Western Europe and North America. IRE and AECL both have a capability
of 3000-5000
Ci per batch. The number of
batches
per
week
can vary
according to the
demand.
It is estimated that this
installed
capacity
99
can
supply current world's
needs for Mo on a reliable basis. KfK
99
has demonstrated a capability of producing 1000 Ci Mo per
week
on a
routine basis, however, their mandate excludes them from commercial
activities and their efforts are dedicated to research into process
development.
Several companies, including
the
largest producers
of ^xc
generators
in
industrialized countries, have chosen on economical grounds to
9 9 m _ 99
manufacture TC generators by purchasing fission Mo
rather
than
by
producing
it. In
certain developing
countries,
however,
there are
99
more than simple economic factors that may drive the demand for Mo
fission production. Socio-economic factors, hard currency
availability
and
a
need
for technological
development
provide
some
of the
driving
forces.
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99
Before undertaking production of fission Mo, a country must first
have
or develop an
appropriate
infrastructure.
This includes
a
suitable
13 2
reactor with a flux greater than 10 n/cm .sec, an isotope
processing
facility
with Health Physics,
Regulatory Affairs, Quality
Assurance
and
Quality Control organizations.
In
such
a
facility,
appropriate hot cells each with sufficient shielding and
glove
boxes are
estimated
to be a
minimum requirement.
In
addition
there
can be
significant costs associated
with
technology
transfer, training
and
start-up.
The country
should
also
have
adequate waste storage and management
facilities.
However,
if
these
are on the same site as the processing
facility and
reactor, issues such
as the
acquisition
of
containers
approved
for
road transportation
and the
costs associated with such
transport
might
not be factors. These costs
could
be significant
otherwise.
99
KfK has provided actual costs for a
weekly
production of Mo.
This
includes chemicals, maintenance, waste
disposal,
transportation,
irradiation services,
health
physics, quality control and production.
It was
stated
to be DM 2.4 million
annually. This
did not
take
into
account R&D
costs.
It is
recognized
that an individual country may
choose
not to allocate these R&D costs and overhead to the cost of
99
Mo
production.
With DM 2.4 million (US$1.3 million) one could buy ~ 130 Ci/week of
99
Mo for a period of one
year
(6 day Ci
delivered)
assuming
a
price
of
$200/Ci
which
is appropriate for
that
large volume. This break-even
point of 130 Ci/week will vary from country to
country.
At this
level
of demand, based on the KfK production
costs,
it
seems reasonable that
a
99
country
may
consider making
its own Mo.
There
are
considerations
other than economics
that can be important factors as
stated
earlier.
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7. PROLIFERATION CONCERNS
99
7.1.
Highly Enriched Uranium Contained
in
Fission
Mo
Production
Targets
Due to international
concerns
about the proliferation of weapons-useable
uranium and because
supplies
of highly-enriched uranium
(>20%)
will be
restricted in the future, a programme has begun at ANL to
develop
the
technology for production of fission product molybdenum using targets
containing low-enriched uranium (<
20%)
instead of
highly-enriched
uranium. The status of this work is discussed in the
paper
entitled
"Preliminary
Investigations for Technology Assessment of "MO
Production from LEU
Targets".
99
7.2.
Plutonium Produced in Fission Mo Production
The plutonium produced in
irradiated
targets containing HEU (93%) or LEU
(20%) for
production
of fission product molybdenum is not significant
from a proliferation point of view.
99
Targets
specifically
designed for fission Mo production contain
235 235
between 1 and 15g U. Burnup is
typically
1-2% of the U
99
because the Mo
saturates
in this burnup range. Quantities of
99
plutonium
produced
are
about
1
mg/1000
Ci Mo for
targets
containing
99
HEU and about 21 mg/1000 Ci Mo for
targets
containing
LEU. Curies
are defined
here
at the time of removal
from
the reactor and the Pu
239 239
includes
both
Pu and Np.
With
LEU targets, it would
require
99
production (at the
reactor)
of about 48.000 Ci Mo to
produce
l g of
99
Pu.
That
is, about lg of Pu would be
produced
per year for a Mo
production rate of 1000 Ci per
week.
This rate of Pu production is not
significant.
7.3.
Uranium Recycling
Some
concern
was expressed about the
possibility
that the
transfer
of
99
technology for uranium recovery from the Mo fission
production
process may potentially lead to activities in
sensitive areas such
as
reprocessing
of
irradiated
fuel elements. It
must,
however,
be
recognized
that
such
transfer would be limited to
small scale
operations
aimed
exclusively
at the recovery of the
valuable uranium from
LEU as
well as HEU
targets.
In both cases the production of Pu is
negligible
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and the underlying
chemical process
flowsheets are well described in the
open literature. Further,
it is recogniEed
that
the KfK process
technology is not directly applicable to the recovery of fissionable
materials other
than
uranium.
8. SAFEGUARDS
Safeguards requirements
must
be fulfilled by a very strict (at the mg
235
level)
U and U
total
balance for each
area
and at all times.
Documented reports must be sent at regular periods to national and
99
international authorities. Fission Mo producers must accept regular
inspections
by
national
and
international authorities,
particularly by
IAEA officers.
9. QUALITY ASSURANCE
AND
QUALITY CONTROL
99
For fission Mo, a
quality
assurance programme must be
completely
described
including:
-
detailed
description of the facility and equipment,
detailed
description
of the
whole
process, such as targetry,
irradiation, chemical process, storage,
waste
and recovery,
- personnel
training,
good
manufacturing
practices and good
laboratory practices,
technical
procedures.
99
Final Mo
quality
must be
described
by
precise specifications
of
radionuclidic and radiochemical
purities
in
addition
to other
requirements
such as specific activity, pH and nature of solution as
described
in the
international
pharmacopoeia.
Final
product
quality must
be
assessed
by a qualified quality
assurance
officer
who is functionally
independent
from the production department
and
assumes personal responsibility for the assessment.
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10. POSSIBILITIES FOR TECHNOLOGY TRANSFER
99
Efficient and reliable international
suppliers
of Mo are in
existence today, with
estimated
total
capabilities
sufficient
to
supply
the entire
current
world
demand.
However, for a variety of
reasons,
some organizations in
developing
countries may
wish
to undertake
99
indigenous
production of
fission
Mo for
medical
applications. The
meeting considered and discussed several areas in which the
IAEA
may
assist these organizations in achieving their goal
through
a process of
technology transfer.
Nuclear Reactor Requirements
99
Before embarking
in Mo fission production, the
organization should
make sure
that adequate
irradiation
facilities
are
available.
These
facilities should include
a nuclear research
reactor
with the following
characteristics: (a)
Irradiation
positions with adequate thermal
neutron
flux greater than 10 n/cm .sec must be available- . The
ability
to insert and remove targets without interrupting reactor operation is
desirable
but not
necessary,
(b) The coolant flow in the irradiation
positions
must
allow irradiation
of the fission
targets
with
acceptable
thermal-hydraulic safety margins, (c)
Operation
of the
reactor
must be
reliable and
continuous,
with sufficiently
high
load
factors, (d)
Other
uses of the reactor are desirable to reduce the fraction of the
99
operation costs to be allocated to Mo production.
Safety
Considerations/Regulatory
Aspects
Irradiation
of the targets is normally regulated by the same
organization
which has regulatory responsibility for the operation of
the reactor. In all probability, the same criteria
applied
to
evaluate
the safety of the reactor fuel will be used to evaluate the
safety
of
the targets.
Thus,
thermalhydraulics
considerations
will dictate the
maximum power of the
targets,
their uranium content, and the uniformity
requirements
for their
loading.
The safety aspects of the fissile
-
/
Experience
shows
that to obtain a
99
Mo
activity
of about 150 Ci at a
calibration time of 6 days after the end of
irradiation,
a thermal
neutron
flux
of 3 to 4 x lO^ n/cm^ sec is
required.
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material used in the targets
will
also be
evaluated
in a
manner
consistent
with the evaluation of the reactor
fuel. Thus,
targets using
the
same
material as the reactor fuel material will be
easiest
to
license.
The safety
aspects
of
target
processing must be addressed in a
separate
safety report, which must include a
detailed
quality
assurance
programme
(see Chapter 9 on
quality assurance
programme).
Waste
Disposal
An
adequate
waste
disposal/uranium recovery
system
must
be
available
before
start-up
of the facility (see hapter 5 on waste
disposal).
Man-power
Requirements
An
infrastructure
of skilled
personnel
in
nuclear, chemical
and
radiochemical
fields must be available.
Availability of
Fuel
HEU
supplies may be limited in the
future.
Organizations in developed
countries
are
investigating
the
feasibility
of
using
LEU
targets
in
their facilities.
Organizations
in developing
countries should
take
this
development into account (see Chapter 7 on
Proliferation
Concerns).
Economical Aspects
99
The demand for Mo
which
the
proposed facility
is planned to
satisfy
99
must
be
assessed realistically
in
terms
of
quantity
of Mo needed per
week
in the various
nuclear
medicine
centres
of the
country.
The
level
of demand is essential to
determine
the unit cost of the produced
99
Mo. A realistic
estimation
of the
unit
cost should take into
account several factors such as R & D costs,
capital
investment of the
production plant, operation costs,
quality control and maintenance of
all the relevant facilities. The assessment can be done by conducting a
technical-economical feasibility study.
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11. SUMMARY OF CONCLUSIONS AND RECOMMENDATIONS
1.
Since
the establishment of
indigenous production facilities
of
fission
99
Ho for
medical
use requires
serious considerations
of
technical
and
economical nature,
it is highly
recommended that
careful
pre-feasibility
and feasibility studies be conducted before further commitments are
made. The Agency may
play
a role, in co-operation with
external
experts, to help the
country
concerned to define the terms of
reference
for such
feasibility
studies.
2. It is
recognized that
safety and
regulatory aspects
are of
paramount
importance for a successful
production
programme.
Therefore,
it is
recommended
that both
national
and international safety regulations
should be
strictly
followed.
3.
Because of the technical
complexity
of the matter, it is
necessary that
the staff involved in all phases of the
production
programme be well
trained and
highly qualified.
Here
again,
the
Agency
may play an
important role through its Fellowship Programme.
4. It is expected that in about two
more
years new developments in target
materials and technology as well as chemical processing may take place,
which
will
take
into
account the
future
unavailability of highly
enriched
uranium
for
targets.
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PAPERS PRESENTED AT THE MEETING
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OPERATION OF THE INSTALLATION FOR FISSION Mo
PRODUCTION
IN ARGENTINA
R . O .
M A R Q U É S ,
P . R . C R I S T I N I ,
H.
FERNANDEZ,
D.
MARZIALE
Direction
de
Radioisotopes
y
Radiaciones,
Comisiön Nacional
de
Energia A t ö m i c a ,
Buenos
A ir e s ,
Argentina
Abstract
The
paper describes the
efforts
of the
Argentine Atomic
Energy Commission to
9
9
establish a programme to produce fission Mo for the
preparation
of
99
*c generators. Th e producti on
plant
has been completed in
1987
and has
started
limited pr o d u c tio n runs.
The hot
cells consist
of
four
hot cells
with
a
stainless
s t e e l lining.
The chemical separation process of * * M o from
the
i rra d i a t e d A l / A l l o y
(90 n r ic hed) targets is similar to the
pr o c ess
de ve l ope d
by A. Sameh in the
Fed er al Rep u blic
of Germany. The
pr o d u c t
sp ec if ic atio n
conforms
very well with the requir ements for a safe use in the
p r e p a r a t i o n of x c ge ne ra t or for m e d i c a l u s e .
O n
1 9 8 5
t h e A r g e n t i n e A t o m i c C o m i s s i o n b e g a n t h e o p e r a t i o n
o f t h e i n s t a l l a t i o n f o r p r o d u c t i o n o f
f i s s i o n
M o - 9 9 .
T h i s
f a c t i s t h e
r e s u l t
o f a
p r o j e c t i n c l u d e d
i n t h e G e r m a n
A r g e n t i n e a g r e e m e n t , h a s i n v o l v i n g t e c h n o l o g y t r a n s f e r t o o u r
c o u n t r y
o f t h e p r o d u c t i o n
m e t h o d d e v e l o p e d
b y D r .
S a m e h
A l l a t K F K .
T h e d e c i s i o n o f p r o d u c i n g f i s s i o n M o - 9 9 i n A r g e n t i n e
R e p u b l i c
w a s
t a k e n
s o m e y e a r s
a g o b e c a u s e
o f
i n c r e a s i n g
d e m a n d i n t h e
m e d i c a l f i e l d f o r f i s s i o n M o l y b d e n u m g e n e r a t o r s . T h e n e e d f o r
M o - 9 9
h a s b e e n i n c r e a s i n g u p t o a
v a l u e
o f 8 0 C i / w e e k a t p r e s e n t .
T h u s 1 0
y e a r s
a g o
C N E A
d e c i d e d t h e c o n s t r u c t i o n o f a
s u i t a b l e
p l a n t f o r f i s s i o n p r o d u c t s p r o c e s s i n g . T h i s i n s t a l l a t i o n , w i t h
s e v e r a l m o d i f i c a t i o n s ,
i s t h e o n e
o p e r a t e d
a t
p r e s e n t .
I t i s
p l a c e d
i n a
r o o m
o f 8 0 m
2
i n t h e
r a d i o i s o t o p e p r o d u c -
t i o n
p l a n t ,
n e x t
t o
R A - 3
n u c l e a r r e a c t o r , a l l o w i n g i n
t h i s
w a y a
f a s t a n d
s a f e t r a n s f e r
o f i r r a d i a t e d t a r g e t s t o t h e p r o c e s s i n g
23
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h o t c e l l .
F o u r
h o t c e l l s w e r e s e t t l e d t h e r e : t w o o f t h e m a r e
m a i n ,
s h i e l d e d
w i t h 2 0 c m o f P b . T h e i r d i m e n s i o n s a r e 2 x 1 , 5 x 1 , 5 m ,
b e i n g
e q u i p p e d w i t h m a s t e r s l a v e m a n i p u l a t o r s
a n d
w i t h d o u b l e d o o r
F r e n c h s y s t e m .
T h e
t h i g t
c o n t a i n m e n t b o x e s
a r e
b u i l t
i n
s t a i n l e s s s t e e l ,
w i t h
a n
i n t e r n a l
c o a t i n g o f e p o x i p a i n t . T h e o t h e r t w o a r e
a u x i l i a r y h o t c e l l s e q u i p p e d w i t h m a n i p u l a t o r s , a n d
t h e i r
d i m e n -
s i o n s a r e 1 x 1 x 1 m ,
s h i e l d e d w i t h
1 0 c m o f
l e a d .
T h e
l o w e r
p a r t
o f t h e c e l l s a r e u s e d t o
p l a c e s e v e r a l t a n k s
f o r
c o l l e c t i o n
a n d
s t o r a g e o f
l i q u i d
w a s t e a n d d i s p o s a l o f g a s e o u s w a s t e .
T h e
e n g i n e
r o o m w a s
p l a c e d
i n a
s p a c e b e t w e e n g r o u n d
a n d
f i r s t f l o o r .
L a t e r o n i t
w i l l
b e
s h o w n
t h a t t h e
c h a r a c t e r i s t i c s
o f t h i s i n s t a l l a t i o n a r e v a r y i n g b e c a u s e o f i t s a m p l i f i c a t i o n .
I r r a d i a t i o n t a r g e t s
T h e
t a r g e t c o n s i s t s
o f a n A l / U
a l l o y c o r e
( U A 1
V
)
w i t h
1 g
A
U r a n i u m e n r i c h e d t o 9 0 % , w h i c h i s
A l u m i n i u m - w r a p p e d
a s a s a n d w i c h
I t
i s 1 3 c m
l o n g ,
3 , 6 c m w i d e a n d 0 , 1 5 c m t h i c k . T h e w e i g h t o f
A l
i s 1 3 g r ( e a c h ) . T h e s e t a r g e t s a r e p r o d u c e d b y t h e N u c l e a r
F u e l D e p a r t m e n t o f C N E A , e m p l o y i n g n a t i o n a l t e c h n o l o g y .
I r r a d i a t i o n c o n d i t i o n s
T h e p l a t e s , p r o p e r l y
d i s p o s e d ,
a r e p l a c e d i n
R A - 3
r e a c t o r
IT
O
c o r e , e x p o s e d
t o a
n e u t r o n f l u x
o f 3 x 1 0 n / c m s e c a n d u s i n g
t h e
c o o l i n g s y s t e m
o f t h e
r e a c t o r . B e c a u s e
o f t h e
n e e d
o f
c h a n g i n g
t h e r e a c t o r c o r e ( i t i s n e c c e s a r y t o g o f r o m 9 0 % t o 2 0 %
e n r i c h -
m e n t ) f r o m
t h e
b e g i n n i n g
o f
t h i s y e a r
t h e
r e a c t o r
i s
o p e r a t i n g
w i t h a g e d
f u e l
e l e m e n t s ,
w h i c h p r o d u c e a
r e a l f l u x
o f
a b o u t
1 , 5 x 10
13
n / c m
2
s e c .
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T h e i r r a d i a t i o n t i m e
o f t h e
p l a t e s
i s 5 c o m p l e t e d a y s , a n d
a f t e r ,
t h i s t h e y a r e
c o o l e d
1 6 h o u r s i n t h e
r e a c t o r p o o l b e f o r e
t r a n s p o r t a t i o n f o r
p r o c e s s i n g .
A t i g h t c a n i s u s e d t o c o n t a i n t h e i r r a d i a t e d p l a t e s f o r
t r a n s p o r t
f r o m
t h e
r e a c t o r
t o t h e
p r o c e s s i n g
h o t
c e l l .
.
T r a n s p o r t a t i o n
o f i r r a d i a t e d t a r g e t s
T h e r e c e p t i o n o f t h e t i g h t c a n w i t h t h e
i r r a d i a t e d
p l a t e s
f r o m
t h e r e a c t o r a n d
t r a n s p o r t a t i o n
t o t h e p r o c e s s i n g
c e l l s
a r e
c a r r i e d
o u t w i t h a s e l f - p r o p e l l e d
s h i e l d i n g
s p e c i a l l y d e s i g n e d
f o r
t h i s
p u r p o s e . T h e w e i g h t o f t h e
s h i e l d i n g
i s a b o u t 2 , 5 T n a n d
t h e
t h i c k n e s s
o f P b i s 2 3 c m .
A s t h e h e i g h t o f t a r g e t
r e c e p t i o n
a t R A - 3 r e a c t o r a n d t h e
h e i g h t o f t h e e n t r a n c e s y s t e m a t t h e c e l l d i f f e r i n a b o u t 1 m ,
t h e p o s i t i o n o f t h e s h i e l d i n g d o o r c a n b e v a r i e d b e t w e e n t h o s e
l i m i t s .
l o d g e m e n t i n s i d e t h e
s h i e l d i n g
a l l o w s
a
c o n v e n i e n t
e n e r g y
d i s s i p a t i o n . I n o r d e r t o e n t e r p l a t e s i n t h e h o t c e l l , t h e d o u b l e
d o o r
L A C A L H E N E
s y s t e m
h a s
b e e n m o d i f i e d , a l l o w i n g
t h e
o p e r a t i o n
t o b e m a d e i n l e a k - p r o o f c o n d i t i o n s .
D e s c r i p t i o n o f t h e p r o c e d u r e
A s c a n b e s e e n i n F i g I t h e a d j u s t m e n t o f o p e r a t i o n o f t h e
i n s t a l l a t i o n w a s d i v i d e d i n f o u r s t a g e s .
T h e p r o c e d u r e f o l l o w e d f o r p r o c e s s i n g t h e p l a t e s i s t h e o n e
d e v e l o p e d b y D r . S a m e h ( F i g . I I ) . A t t h i s p o i n t , i t i s
c o n v e n i e n t
t h e f o l l o w i n g c o m m e n t s c a n b e m a d e a b o u t t h e e q u i p m e n t e m p l o y e d .
O w i n g t o
d i f f i c u l t i e s
f o r g e t t i n g i m p o r t e d
e l e m e n t s ,
s e v e r a l o f
t h e m
w e r e
r e p l a c e d .
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FIRST STAGE:
S E C O N D S T A G E :
T H I R D S T A G E :
F O U R T H STAGE:
STARTING
OF
INSTALLMENT
O P E R A T I O N
N O N C O M M E R C I A L P R O D U C T I O N
C H A R A C T E R I Z A T I O N
O F F I N A L
P R O D U C T (Mo-99)
E M P L O Y M E N T OF Mo-99 IN
G E N E R A T O R
PRODUCTION
( N O N - C O M M E R C I A L PRODUCTION)
R O U T I N E P R O D U C T I O N F O R
C O M M E R C I A L
PURPOSES
«
IRRADIATION
SYSTEM
* T R A N S P O R T D E V I C E F O R
I R R A D I A T E D
T A R G E T S
* P R O C E S S I N G
STEPS
• R A D I O N U C L I D I C P U R I T Y
' C H E M I C A L C H A R A C T E R I S T I C S AND R A D I O C H E M I -
C A L P U R I T Y
• B E H A V I O U R OF F I S S I O N Mo-99 IN A L U M I N A
COLUMNS
•
C H A R A C T E R I S T I C S
OF
E L U T E D Tc-99
m
v
* G E N E R A T O R
E F F I C I E N C Y A N D
Y I E L D I N G
• W E E K L Y
P R O D U C T I O N
OF Mo-99
*
L I Q U I D W A S T E
DISPOSAL
* D I S O L U T I O N O F
I R R A D I A T E D U-235
A N D
L A T E R
P U R I F I C A T I O N
»
A L L
THESE
S T A G E S I N V O L V E
P E R S O N N E L
L I C E N S I N G A N D
D O C U M E N T A T I O N
E V A L U A T I O N B Y T H E
R E G U L A T O R Y B O D Y .
F I G. I
L._.J
LJzz:
1 3 1 1
Mo
Fission product
Uranium
133
Xe
FIG.II
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F o r
i n s t a n c e t a n t a l i u m r e a c t o r s
c h a n g e d
t o P . V ; C
s p e c i a l l y
m o l d e d r e a c t o r s , w i t h a w a l l t h i c k n e s s o f a b o u t 1 c m w h i c h a l l o w s
w o r k i n g
i n v a c u u m
c o n d i t i o n s
w i t h o u t a n y d i f f i c u l t i e s .
T h e t a n t a l i u m o r s t a i n l e s s s t e e l v a l v e s w e r e r e p l a c e d b y
s p e c i a l l y d e s i g n e d a n d b u i l t P V C
v a l v e s .
T h e e x c h a n g e
c o l u m n s
a r e
c o n t a i n e d i n P V C t u b e s ,
a l s o
s p e c i a l l y d e s i g n e d , t o b e a r t h e
d e p r e s -
s u r e c o n d i t i o n s
o f t h e
p r o c e s s .
I n t h i s w a y , r e - c h a n g e a b l e e l e m e n t s h a v e
d i s p o s a b l e
c h a r a c -
t e r i s t i c s ,
b e c a u s e t h e
r e p l a c i n g
o f
t h e s e
e l e m e n t s
d o e s
n o t
r e p r e s e n t
a n i m p o r t a n t
e x p e n s e .
T h e
m e t h o d o l o g y e m p l o y e d i n v o l v e s
d e p r e s s u r e c o n d i t i o n s
d u r i n g
a l m o s t a l l t h e p r o c e s s i n o r d e r t o k e e p t h e
f i s s i o n g a s e s
i n a c l o s e d s y s t e m . T h e
i r r a d i a t e d
t a r g e t s , i n t h e f i r s t c h e m i c a l
s t e p , a r e d i s s o l v e d i n h o t a l k a l i n e m e d i u m w i t h a c o n t i n u e s f l o w
o f N
2
.
T h e
s o l u t i o n ,
a f t e r
c o o l i n g , i s f i l t e r e d
t h r o u g h
a
f a t t e d
p l a t e , b u i l t i n s t a i n l e s s s t e e l .
T h e
i n s o l u b l e r e s i d u e c o n t a i n s U r a n i u m a s d i u r a n a t e a n d
U r a n i u m d i o x i d e , t o g e t h e r
w i t h
i n s o l u b l e f i s s i o n
p r o d u c t s
s u c h
a s R u t h e n i u m , Z i r c o n i u m , N i o b i u m a n d L a n t h a n i d e s .
T h e f i l t r a t e c o n t a i n s M o l y b d e n u m , t o g e t h e r w i t h t h e A l u m i n a t e
a n d t h e s o l u b l e f i s s i o n p r o d u c t s s u c h a s I , T e
a l k a l i n e
a n d
a l k a l i n e e a r t h c a t i o n s , S b ( a n d s o on).
A t t h i s p o i n t w e c a n t o c a r r y o u t t h e r e c u p e r a t i o n o f 1 - 1 3 1
w i t h s o m e
s u c c e s s .
A f t e r t h e f i r s t s t a g e , t h e
p u r i f i c a t i o n
o f M o - 9 9 i s c a r r i e d
o u t m a i n l y b y
i o n i c
e x c h a n g e c r o m a t o g r a p h y . I t h a s b e e n t h o r o u g l y
s t u d i e d
d u r i n g t h e a d j u s t m e n t o f t h e o r i g i n a l m e t h o d , s p e c i a l l y
l o a d i n g r a t e a n d w a s h i n g o f t h e
c o l u m n s ,
i n o r d e r t o r e a c h a d e -
q u a t e
d e c o n t a m i n a t i o n
f a c t o r s . A s a r e s u l t o f t h e s e s t u d i e s , t h e
27
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l o a d i n Q ,
w a s h i n g a n d e l u t i o n r a t e s h o u l d n o t b e g r e a t e r t h a n
8 m l / m i n t o o b t a i n a f i n a l
p r o d u c t
o f g o o d q u a l i t y .
T h e r e f o r e a f i r s t a n i o n i c
e x c h a n g e
c o l u m n
A G - 1
i s
l o a d e d
w i t h
t h e
f i l t r a t e
s o l u t i o n .
A f t e r w a s h i n g ,
t h e M o i s
e l u t e d
d i r e c t l y t o t h e
s e c o n d
m a i n h o t
c e l l
t o c a r r y o u t t h e n e x t s t e p
o f t h e p u r i f i c a t i o n p r o c e s s : c o m p l e x i n g M o w i t h
p o t a s s i u m
t h y o c i a n a t e i n
a c i d
m e d i u m , i n o r d e r t o
o b t a i n
t h e
w e l l
k n o w n
c o m p l e x M o O
(SCN)
4
~
T h e p u r i f i c a t i o n
s t e p
f o l l o w i n g t h e
M o - S C N
c o m p l e x f o r m a t i o n
i s t h e
p a s s a g e
t h r o u g h a
C H E L E X
1 0 0 r e s i n
c o l u m n
i n i t s a n i o n i c
f o r m ,
w h e r e
t h e
c o m p l e x
i s r e t a i n e d
q u a n t i t a t i v e l y .
A f t e r t h e w a s h i n g o f C H E L E X c o l u m n , t h e e l u t i o n o f M o i s
p e r f o r m e d w i t h
h o t N a O H s o l u t i o n
(50eo.
T h e n e x t
s t e p
i s t o
r e p e a t
t h e
f o r m a t i o n
o f
M o - S C N c o m p l e x
a n d i t s p a s s a g e t h r o u g h a C H E L E X
1 0 0 - 2 0 0
r e s i n c o l u m n ,
w i t h
t h e
s a m e w a s h i n g
a n d
e l u t i o n c o n d i t i o n s ,
t o
g u a r a n t e e
t h e
p u r i t y
o f
t h e
f i n a l p r o d u c t .
T h e
w h o l e
p r o c e s s i s
c a r r i e d
o u t
u n d e r d e p r e s s u r e
c o n d i t i o n s t o a v o i d t h e e s c a p e o f
f i s s i o n
g a s e s , w h o s e d i s p o s a l
w i l l
b e e x p l a i n e d l a t e r o n .
T h e l i q u i d c i r c u l a t i o n i s c a r r i e d o u t
d u r i n g a l m o s t
a l l
t h e
p r o c e s s
b y d e p r e s s u r e c o n d i t i o n s ( p r o d u c i n g s u i t a b l e A P ) . i f
n e c e s s a r y , w i t h t h e h e l p o f p u l s a t i n g p u m p s .
W i t h
t h e
e l u t i o n
o f M o f r o m t h e s e c o n d r e s i n c o l u m n , t h e
o p e r a t i o n
i n
c e l l
I I i s
c o m p l e t e d ,
a n d t h e
e l u a t e
i s
c a r r i e d
t o
t h e s e c o n d a u x i l i a r y
c e l l
w h e r e p H i s a d j u s t e d t o a v a l u e o f 3 , 5
b e f o r e
p a s s i n g t h e
s o l u t i o n
t h r o u g h a n
A ^ O - j
c o l u m n , w h i c h i s
t h e l a s t s t e p
o f
p u r i f i c a t i o n .
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W a s h i n g
t h i s
c o l u m n i s m a d e
w i t h
a
d i l u t e
H N ü V j s o l u t i o n a n d
w a t e r , p a y i n g s p e c i a l a t t e n t i o n t o w a s h i n g r a t e . F i n a l l y M o i s
e l u t e d
w i t h
N H - j s o l u t i o n i n a v o l u m e o f 3 0 m l .
W a s t e
D i s p o s a l :
a )
G a s e o u s :
i ) D i s s o l u t i o n : t h e H
2
p r o d u c e d d u r i n g
d i s s o l u t i o n
o f A l / U p l a t e s
i n a l k a l i n e m e d i u m
i s
d r i v e n i n t o
a n
o x i d a t i o n s y s t e m w i t h
C u O a t
4 0 0 Q C
a n d t h e f o r m e d
w a t e r
i s
c o n d e n s e d .
T h e
r e m a i n i n g
g a s e s ( a n i t r o g e n s t r e a m p e r m a n e n t l y c a r r i e s t h e f i s s i o n g a s e s
t h r o u g h t h e
s y s t e m )
a r e c o l l e c t e d i n p r e - e v a c u a t e d s t a i n l e s s
s t e e l
t a n k s
( t o t a l
v o l u m e :
4 0 0 1 ) .
A f t e r
a
w e e k
o f
s t o r a g e
t h e
g a s e s a r e t r a n s f e r r e d t o f o u r
t a n k s
( 1 0 0 1
e a c h )
w i c h a c t i v a t e d
c h a r c o a l , p l a c e d
t o g e t h e r
w i t h t h e a f o r e s a i d t a n k s u n d e r c e l l
n u m b e r
o n e .
A f t e r
a n o t h e r w e e k o f s t o r a g e t h e g a s e s a r e c a r r i e d i n t o 5
t a n k s ( 8 9 1
e a c h )
w i t h
a c t i v a t e d
c h a r c o a l ( p l a c e d o n t h e t o p o f
c e l l
n u m b e r o n e ) a n d t h e n t h e y a r e d e l i v e r e d t o t h e
v e n t i l a t i o n
s y s t e m o f t h e c e l l s .
A
s t u d y
o f
s e p a r a t i o n
o f
X e - 1 3 3
b y
c h e m i s o r p t X o n
i s c a r r i e d
o u t a t
p r e s e n t
i n o r d e r t o o b t a i n h i g h p u r i t y X e .
M o - S C N c o m p l e x
f o r m a t i o n
i s c a r r i e d o u t i n a p r e - e v a c u a t e d
r e a c t o r a n d i s a c c o m p a n i e d b y p H c h a n g e f r o m a l k a l i n e t o
a c i d
m e d i u m .
P r o d u c e d g a s e s
a r e c o l l e c t e d i n a 1 0 0 1 t a n k
u n d e r
t h e
c e l l a n d a f t e r a w e e k
c a r r i e d
t o
f o u r
t a n k s
( t o t a l
v o l u m e ;
32 0 1 )
w i t h
a c t i v a t e d c h a r c o a l , p l a c e d o n t h e t o p o f m a i n h o t c e l l
n u m b e r
2 .
T h e s e o f f - g a s e s
a r e
d e l i v e r e d
t o t h e v e n t i l a t i o n
s y s t e m
o f
t h e h o t c e l l s , w h i c h
i n v o l v e s
f o u r t e e n 2 0 0 1 t o w e r s , l o c a t e d i n
t h e
c e l l a r c o n t a i n i n g a c t i v a t e d
c h a r c o a l , w h i c h c a n
w o r k
i n
s e r i e s c o n n e c t i o n
o r i n p a r a l l e l . A f t e r p a s s i n g t h e s e
c o l u m n s
t h e
a i r i s f o r c e d t h r o u g h a
b a t t e r y
o f a b s o l u t e
f i l t e r s .
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b )
S o l i d s :
T h e r e s i n c o l u m n s ( A G - 1 x 8 c o l u m n k e p t
i n a
l e a k - p r o o f
s t a i n l e s s s t e e l c y l i n d e r ) a s w e l l a s v a l v e s ,
q u i c k - c o n n e c t s ,
h o s e s ,
c l e a n n i n g p a p e r s ,
a r e t a k e n o u t o f t h e
c e l l w i t h
t h e
f r e n c h P A D I R A C s y s t e m .
c )
L i q u i d s :
i )
H i g h a c t i v i t y l i q u i d w a s t e s f r o m
A G - 1 r e s i n
l o a d i n g
a n d
w a s h i n g :
T h e r e a r e t w o t a n k s
(100
1
e a c h )
u n d e r c e l l n u m b e r 2
t h a t
a l l o w , i n a n a l t e r n a t e d w a y , u p t o 5 m o n t h s o f d e c a y f o r e f f l u e n t s
c o r r e s p o n d i n g t o
t h i s s t a g e
( a b o u t 3 , 5 1 p e r
e a c h p r o c e s s i n c l u -
d i n g
w a s h i n g
s o l u t i o n s ) .
i i ) M e d i u m a c t i v i t y l i q u i d w a s t e s :
F i v e
1 0 0 1
t a n k s a l l o w
t h e
s t o r a g e
o f
l i q u i d s c o m m i n g f r o m
C H E L E X
I a n d I I
p r e - w a s h i n g
a n d
l o a d i n g a c i d
w a s h i n g s o f c e l l
n u m b e r
I I
e q u i p m e n t ( a b o u t
1 1 1 p e r p r o c e s s )
d u r i n g
5
m o n t h s .
i l l ) D i s p o s a l a f t e r t h e m e n t i o n e d d e c a y
p e r i o d :
L i q u i d s
( I a n d I I ) a r e
d i s p o s e d
b y
c e m e n t a t i o n i n t o
e v a c u a t e d
l e a k - p r o o f t a n k s (200 1 ) .
C h e m i c a l
a n d
p h y s i c a l c h a r a c t e r i s t i c s
o f
p r o d u c e d
M o - 9 9
I n F i g . I l l a r e s e e n t h e m a i n
c o n t a m l a n t s
o f M o - 9 9
( o b t a i n e d ) .
I t i s w o r t h m e n t i o n i n g
t h a t
b e c a u s e o f l a c k o f s p a c e a f i n a l
p u r i f i c a t i o n
s t e p b y
v o l a t i l i z a t i o n
o f M o h a s n o t b e e n
i m p l e m e n t e d .
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S p e c i f i c a c t i v i t y :
à
1 0 . 0 0 0 Cl/g
M o .
C o n c e n t r a t i o n : > 1.000 m C i / m l .
R a d i o c h e m i c a l
p u r i t y :
9 9
M o
a s
M o l y b d a t e
> 9 9
R a d i o n u c l i d i c
p u r i t y
( w i t h
r e f e r e n c e
M o - 9 9
a c t i v i t y
13 1
I < 1 0 p p m
103
Ru < 2 0 p p m
9 5
N b < 1 p p m
95
Z r < 0 . 1 p p m
1 3 2
T e
_ 1 3 2
I
< 0 1 p p m
^^Ba-^^La N . D
u 1
C e
N . D
1 4
*C e
N .D
o r <
10 ~
4
ppm
FIG.III.
Product specification of fission molybdenum.
A s
w i l l
b e
s e e n l a t e r
o n , a t
p r e s e n t
t h e
i n s t a l l a t i o n
i s
b e i n g
e n l a r g e d ,
w h i c h w i l l i n c l u d e t h i s
v o l a t i l i z a t i o n s t e p ,
l o o k i n g
f o r a n
e n h a n c e m e n t
o f t h e
p u r i t y
o f
f i n a l p r o c e s s .
T h e c h e m i c a l
s t a t e
o f
( o b t a i n e d ) M o - 9 9
h a s b e e n s t u d i e d b y
h i g h t e n s i o n
e l e c t r o p h o r e s i s ,
s h o w i n g
t h a t M o O ^ ( f o r m ) i s
p r e s e n t i n m o r e t h a n 9 9 % i n t h e
f i n a l
p r o d u c t .
T h i s m a t e r i a l i s e m p l o y e d a t
p r e s e n t
f o r t h e p r o d u c t i o n o f
M o - 9 9 / T c - 9 9 m g e n e r a t o r s
w i t h a c t i v i t i e s o f 1 C i o r m o r e .
B e s i d e s w h e n s t u d y i n g
e l u t i o n c u r v e s
a n d e l u t i o n r e s p o n s e
( y i e l d )
i t c a n b e s e e n t h a t t h e y
g r e a t l y
o v e r p a s s
t h e s e o b t a i n e d
w i t h i m p o r t e d M o - 9 9 , t h a t i s
e m p l o y e d
a l s o i n g e n e r a t o r
p r o d u c -
t i o n
a t p r e s e n t .
3 1
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C o m m e n t s a b o u t p r o d u c t i o n p r o c e s s
A f t e r a b o u t
4 0
p r o d u c t i o n
p r o c e s s s e s , i t h a s
b e e n
d e m o s t r a t e d
t o b e h i g h l y r e l i a b l e a n d a t t r a c t i v e
b e c a u s e
i t a v o i d s t e d i o u s
o p e r a t i o n s
o f s e p a r a t i o n b y e x t r a c t i o n o r p r e c i p i t a t i o n .
T h e
p r o c e s s
y i e l d
i s g r e a t e r
t h a n
80%,
t a k i n g
i n t o
a c c o u n t
t h e t h e o r e t i c a l d a t a
o b t a i n e d
a p p l y i n g t h e O R N L O r i g e n
P r o g r a m m e
t o o u r
i r r a d i a t i o n
c o n d i t i o n s .
T h e o p e r a t i o n
c a n b e c a r r i e d o u t i n
h i g h l y r e l i a b l e c o n d i -
t i o n s .
W e h a v e p r o c e s s e d f r o m 1 g t o 4 g o f
U - 2 3 5 w i t h o u t h d i f f i -
c u l t i e s
( e a c h
U r a n i u m
g r a m
i s
a c c o m p a n i e d
b y 1 3 g o f A l u m i n i u m ) ,
w i t h o u t h a f f e c t i n g y i e l d . O b t a i n e d M o - 9 9 , i s
s u i t a b l e ,
f o r
g e n e -
r a t o r p r o d u c t i o n , w i t h a s a t i s f a c t o r y
r e s p o n s e .
U - 2 3 5 P u r i f i c a t i o n
a n d
f u t u r e b u i l d i n g
A s w e a r e n o t a l l o w e d t o
a c c u m u l a t e m o r e t h a n
5 0 g o f
U - 2 3 5
i n
e a c h c e l l ,
w e h a v e
b e g u n w i t h
t h e d i s s o l u t i o n o f t h e p r e c i p i -
t a t e
f o r m e d
d u r i n g t h e
a l k a l i n e
t r e a t m e n t o f t h e i r r a d i a t e d
t a r g e t s
( t h e p r e c i p i t a t e c o n s i s t s m a i n l y o f U 0
2
a n d
i n s o l u b l e
c o m p o u n d s ) .
F o r
t h i s o p e r a t i o n
w e
h a v e d e v e l o p e d
a n e q u i p m e n t t h a t
a l l o w s
t h e
t r a n s f e r e n c e
o f t h e p r e c i p i t a t e
f r o m
t h e f i l t e r t o a d i s s o l v e r
a n d l a t e r
f i l t r a t i o n , o b t a i n i n g
a s o l u t i o n o f U - C 0
3
=
c o m p l e x e s ,
b u t a t
p r e s e n t
w e d o n o t
h a v e e n o u g h
s p a c e t o c o n t i n u e t h e
r e c y -
c l i n g o f u r a n i u m .
F u t u r e f a c i l i t i e s :
A s
I
s a i d
i n t h e b e g i n i n g , w e a r e
w o r k i n g
a t
p r e s e n t
i n a
p l a c e b e l o n g i n g
t o t h e R a d i o i s o t o p e
P r o d u c t i o n P l a n t . D u r i n g
1986
( t h e l a s t y e a r ) t h e
c o n s t r u c t i o n
o f a s p e c i a l
b u i l d i n g
f o r t h i s
p r o j e c t
i s b e e n
c a r r i e d
o u t .
32
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o
T h e n e w b u i l d i n g c o v e r s a n a p r o x i m a t e a r e a o f 6 0 0 f i r a n d
c o m p r i s e s
a
p r o c e s s i n g r o o m w i t h c a p a c i t y
f o r t h r e e n e w c e l l s .
U r a n i u m l a b o r a t o r i e s , c h e m i c a l a n d r a d i o c h e m i c a l l a b o r a t o r i e s
a n d d r e s s i n g
r o o m .
O n t h e f i r s t f l o o r a r e
o f f i c e s
a n d v e n t i l a t i o n
e n g i n e s ; f i l t e r s r o o m i n
f i r s t
a n d s e c o n d f l o o r .
A c o m m u n i c a t i o n d u c t h a s b e e n
p r e p a r e d
b e t w e e n c e l l s i n
o p e r a t i o n a t p r e s e n t a n d
t h o s e
t o b e
c o n s t r u c t e d
i n t h e f u t u r e
i n o r d e r t o w o r k w i t h a l l t h e c e l l s i n c o n n e c t i o n . T h i s s t r u c t u r e
w i l l a l l o w t h e
s e p a r a t i o n
o f
X e - 1 3 3
a n d 1 - 1 3 1 , f o r p u r i f i c a t i o n
o f M o - 9 9 b y v o l a t i l i z a t i o n a n d t h e c o m p l e t i o n o f t h e r e c y c l i n g
o f U - 2 3 5 .
T h e d e s i g n
o f t h e n e w
c e l l s
h a s
b e e n d e v e l o p e d , e n t e r i n g
n o w i n t h e a c q u i s i t i o n s t a g e o f s o m e e l e m e n t s f o r t h e c o n s t r u c t i o n n .
T h e
m a i n d i f f i c u l t y a t
p r e s e n t
i s t h e
r e a c t o r :
o w i n g t o t h e
p r o j e c t e d
c h a n g e i n t h e
c o r e
(90% t o 2 0 % e n r i c h m e n t ) i t h a s t o
s t o p f o r a l o n g p e r i o d . I n o r d e r t o c o n t i n u e
w i t h
t h e p r e s e n t
p r o g r a m m e , w e h a v e b e g u n s t u d i e s i n t e n d i n g t o i r r a d i a t e t a r g e t s
i n t h e r e a c t o r o f t h e
C N E A
i n
B a r i l o c h e
( i n t h e s o u t h o f t h e
A r g e n t i n a H h a t
c a n r e a c h a n e u t r o n
f l u x
o f 3 x
l O ^ n / c m
2
sec.
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DEVELOPMENT OF THE Mo
PROCESS
AT
CRNL
K . A .
B U R R I L L ,
R . J .
H A R R I S O N
C h a l k
R i v e r
N u c l e a r Laboratories,
At o m ic
Energy of Canada
Limited,
Chalk River, Ontario,
Canada
Abstract
Highly
enriched uranium
( H E U )
is used for
Ho-99 production
ac
CRNL.
Dissolution
of the targets and loading of the solution
onto
A12Û3 columns
is discussed. Development work continues to reduce processing
time
and
overall
product
cost. A. process for
treating
the
fission
product
waste has
been
selected
and a
facility
for processing is
being designed.
Low enriched uranium
( L E U )
is planned for targets
eventually.
Our experience
with
Si-based
fuel
for
targets
is poor, and
alternatives
are
being
sought.
1. INTRODUCTION
The production of crude
Mo-99
at CRNL has
grown
ten fold
over
the
past
ten
years.
The process is based on
that developed
at Brookhaven [Ij in the
1950's, but a
large
experience base has built up which is in
itself
a
valuable technology. The
Mo-99
is purified via a proprietary process by
the AECL
Radiochemical
Company
before
it is used in Tc-99
m
generators.
Development has focussed partly on cost reduction. Interim waste
treatment
is being postponed by
tank
storage, and work is underway to
apply processes
that
have
been
developed to treat
this
waste.
Finally,
conversion
of the
uranium from
93% enriched in
U-235
to 20% enriched in the
fuel
is
anticipated
and its
influence
in the