Fission Moly

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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


2/148

FISSION MOLYBDENUM

FOR MEDICAL USE

IAEA,

VIENNA,

1989

IAEA-TECDOC-515

ISSN 1011-4289

Printed

by the IAEA in Austria

June

1989


3/148

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.


4/148

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


5/148

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.


6/148

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


7/148

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


8/148

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).


9/148

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.


10/148

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.


11/148

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.

10


12/148

(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.

1 1


13/148

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.

1 2


14/148

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.

1 3


15/148

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.

14


16/148

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

1 5


17/148

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.

1 6


18/148

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.

1 7


19/148

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.

18


20/148

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.

19


21/148

PAPERS PRESENTED AT THE MEETING


22/148

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


23/148

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 .

24


24/148

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 .

25


25/148

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

26


26/148

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


27/148

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 .

28


28/148

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 .

29


29/148

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 .

30


30/148

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


31/148

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


32/148

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.

33


33/148

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

Date post:	07-Jul-2018
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