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Foire international*des Industriesnucleates

InternationalNuclearIndustries Fair

16-21 October 1972Basel/Switzerland

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Technical Meeting No. 4/12

Heavy Watsr Production in Canada

RJ. KeatingL.R. Nordby

Atomic Energy of Canada LimitedCan'adian General Electric Co. Ltdi

HEAVY WATER PRODUCTION IN CANADA

byt R.K. KeatingAtomic Energy of Canada Limited

and

L.R. NordbyCanadian General Electric Co., Ltd.

ABSTRACT

This paper is presented to outline the hefivy water production

program in Canada where large scale production is required to satisfy

the requirements of the CANDU program. Three large production plants

have been committed. When all of these plants reach maturity, their ,

combined annual production is expected to be about 1500 Mg.

RESUMJj

Cette note technique est prese'Atee afin del deer ire le

programme d'eau lourde au Canada ou une production de grande envergure

est requise afin de satisfaire aux besoins du programme CANDU. La

construction de trois grandes usines a ete entreprise. Lorsque ces

usines seront completees leui." production annuelle combinSe sera de

l'ordre de 1500 Mg.

AUS2UG

Tjiese Abhandlung umreisst das Programm der

Schwerwasserproduktion in Canada, wo eine Production im grosseii

Masstabe ecforderlich ist, urn die Forderung§n des CANDU-Programms,zu

erfuellen. Drei grosse Pabriken sind im Bau. Wenn dieaa drei Fabriken

ihre Vollendung erreichen werden,

um die 1500 Mg betragen.

wird die jaehrliche G<^atitprodu£tion

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INTRODUCTION

.This paper is presented to outline the heavy wator production

program in Canada where large scale production of heavy water is

required to satisfy the requirements of the CANDU Reactor Program.

Three large production plants have been committed, namely the Glace Bay

Plant at Glace Bay, Noxra Scotia, the Canadian' General Elebtric Company

Limited plant at Port Hawkesbury, Nova Scotia and the Atomic En'ergy of

Canada Limited Bruce Heavy Water Plant on Lake Huron in Ontario. When

all of these plants reach maturity, their combined arnual production is

expected to be about 1500 Mg. To appreciate the magnitude of this

production capacity, the present production capacity outside of Canada,

excluding Russia and China, is less than 300 Mg per year.

o

PROCESS DESCRIPTION

The only economic source of large quantities of deuterium is

natural water. The deuterium concentration in natural water varies

with geographical location. , The Atlantic Ocean, off Nova Scotia, has

approximately 155 parts deuterium per million parts hydrogen. Lake

water in the same province and in Lake Huron ranges between 146 and 150

parts per million.

Each of the plants discussed in this paper eirplcys a form of "the

basic "Girdler-Sulfide" process-for enrichment from natural water to an

isotopig percentage of 20-45% and then a vacuum distillation process

to complete the enrichment to reactor rade of 99.75 mol percent D20.

This combination of processes has been used successfully at the USAEC

Savannah River Plant for almost 20 years.b

"GS" ENRICHIEiG PROCESS

i /, ~ ~The "Girdlern-Sulfide" process is a dual temperature isotopic'- - o i

exchange process. The process fluids are hydrogen julfide (HSS) gas

and natural water (H2p>. h di.agx&oatic representation of the Enrich-

ment Unit of the Port HawJeesbury Plant and the Bruce Pl<*nt is presentedin Fig. 1. These fluids are <

towers operating at pressures

through two different tempera

is represented on Fig. 2. " At

:ountercurrently passed through contacting

of approximately 20 atmospheres and

:ure zones. This count?: current contacting

a lower process teuiperature, the deuterium

atoms tend to concentrate in the water. At a higher process temperature

the deuterium atoms tend less to| concentrate in the water. An Enrich-

ment Stage is therefore a pair oip counter cur rent contacting towers or

tower sections, one operating,at a low temperature and the other at a

high temperature. By optimizing sufficient contacting trays in the hot

and cold sections of each stage and by providing a nuiri>er of stages in

series, enrichment to any desired deuterium .isotopic percentage level

may bs achieved. The lowest practicable t.emperature for the cold tower

(or section) to operate at is approximately 27°C, below which a hydrate

(H2S.>5H20) would form at the operating pressure. The hot tower (or

section) operating temperature is limxted to approximately 130°C to

limit the partial pressure of water vapour in the gas; phase to an

acceptable percentage. As the maximum deuterium" extraction is 20 per-

cent, 35,000 kg of natural water must be processed for each teg of

production. Large supplies of thermal and electrical energy are

required by this process. Continuity of this energy supply has proven ,,

to be very important to the production capacity factors of large single

train units.

DISTILIATION PROCESS '

The final reactor grade product is obtained u&ing a vacuum '

distillation process which is relatively simple and is generally well

known in principle. An overhead stream at a few isotopic percenbage

points less thars the feed stream is recycled to the "GS" Enriching Unit

the distillate is drawn off,''as reactor grade product.

PRODUCTION PLANTSc c i i

CANADIAN GENER&t, ELECTRld PORT HAWKESBURY HEAVY WA ER PLANT

In 1966 a p l a n t with a production' capac i ty of 0.048 Mg/hr was

committed at Per t Hawkesbury, ijJdva S c o t i a , by t h e Canadian General

E l e c t r i c Company Limited. The Jengineering and cons t ruc t ion c o n t r a s t o r'I '

for t h i s p l an t was The Lumraus Company.i

The feedwater and makeup for the recirculat;.ng cooling water

system is taker, from a fresfh water reservoir. Steam i« supplied by a

nearby thermal generating station of the Nova Scotia Power Commission

as exhaust steam from an 80 MW(e) back pressure turbine.1 Electrical

. power can be supplied either directly f ron this generating station or \ '

from the interprovincial grid.

The basic elements of the plant consist of three first stage

fractionating tower pairs (hot and cold) operated in. parallel, one

second stage pair, one third stage pair, plus a vacuum distillation

unit. -- The design concentration factors for these elements are 4:1, 6:1,

130:1 and 3:1 respectively.

Several unique features were employed in the design of this

plant, the most significant of which was the stacking of the hot and

*cold towers in the first and second stages {see Fig. !3). The ratio of -

cross sectional area to column height was such that the cold tower

could be stacked on top cf the hot tower and stilh stay well within

desirable diameter to height ratios. This concept eliminated one tower.,

skirt, two tower heads and a substantial amount of piping and valving

per tower pair. The first stage towers are perhaps the largest pressure

vessels in the world, being approximately 95 meters high and 9 meters

in diameter.

Other significant features include the cascading of gas rather

than- ] iquid from the first to second stage and from second to third

stage. The cascading of the gas stream not only provides a transport

medium for deuterium from one stage to the next but also transports

he^at, thereby making it unnecessary to supply additional heat to the

second and third stages. The recirculating H2S gas stream is heated

and cooled within the first stage pressure vessel, by direct contact .

with the process water which in turn is heat exchanged with steam and

cooling ,water m external tubej-in-shell heat exchangers. The process

design includes several extensive heat recovery heat exchange systems.

! ' °The vacuum distillationj finishing unit is a Sulzer SUM propietary

I ' '

design ut i l iz ing two packed toilers. The f irst tower has a packing mesh>and the second tower has 162 tlobes, packed with copper gauze, operatingin parallel . Product draw offproduct concentration.

• * - ,

is intermittent and automatic*"based on

\- 4 _

BRUCE HEAVY WATER PLANT

The Bruce Heavy Water Plant with a production capacity of

0.096 Mg/hr is owned by Atomic Energy of Canada Limited and is being

commissioned and operated by Ontario Hydro. This plant, located on

the shore of Lako Huron in Ontario,, was committed in late 1968 with

construction beginning in 1969. The plant is beinc, engineered and

constructed by The Lummus Company. The first Enriching Unit of the '

plant is expected to achieve initial production in November 1972. The

second Enriching Unit is expected to be in production in late 1972.

The process feedwater and cooling water -is taken frorrr and

returned to Lake Huron. The steam requirements of the plant can be

provided by either the Douglas Point Muclear Power Station or the

Auxiliary Steam Plant. This plant with three oil fired boilers was

constructed specifically cor this purpose. With this duplication the

reliability of the staam supply is expected to be very good.

The process design of tre Enriching Unit was based on and is

almost identical to the Enriching Unit at the CGE plant, andv therefore

needs no further description. The doubled production capacity is

accomplished by using two identical Enriching Units operating in

parallel (see Fig. 4). •"

The three stag^ Finishing Unit is a Lummus design using sieve-

trayed towers, and is designed to produce 0.096 Mg/hr of reactor grade

heavy water with a deuterium concentration of 30% as its feed.

GLACE BAY HEAVY' W&TER PLANT

In 1963 The Deuterium Coinpany of Canada Limited committed a

Heavy Water Plant at Glace Bay,; Nova Scotia. This plant was to have

;. Iused sea water from the Atlantic Ocean,{for feed and cooling purposes

I 'J

and was to begin production in 1967. However, plagued with a varietyof., problems, including* labour difficulties and corrosion problems

!associated with the use of sea water, it eventually became apparent

that extensive modifications wo'|ald be required before the plant could

go into production. Commission Log efforts ceased in 1969. The plant• r' '

lay idle unti l ] ate in 1971 whsu the Federal Governriient of Canada

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provided the funds to AECL to rehabilitate the plant. AECL now

cbolds a long term lease on the plant and has complete management

responsibility.

The rehabilitation rprogram was initiated quickly and is no\/

progressing rapidly. The work is being undertaken by Canatom Mon-Max.

The rehabilitation program is extensive and, involves re-design

of tha basic process. The original plant was to produce reactor grade

D20 entirely using the "GS" process. The rehabilitated plant will use

the^'GS" process in three stages to produce approximately 20 isotopic

percent D2o and will complete the concentration using a vacuum

distillation unit. Because of the "GS" unit "redesign and the addition

of the Finishing unit, the design capacity-of the rehabilitated plant

will" be 0.053 Mg/hr whereas the original plant was to produce approx-

imately 360 Mg/year at a 95% capacity factor. A fresh water reservoir -

is being created to provide fe^dwater and makeup for s recirculating -

fresh water cooling system. The first D20 production from the plant is

expected early in 1975 with the plant reaching maturity by 1979.

COMMISSIONING'AND OPERATING EXPERIENCE

CANADIAN GENERAL^1 ELECTRIC PORT HAWKESBPRY HEAVY WATER PLANT

Commissioning of utilities at the CGE plant started during May

of 1969 but was halted iin June due to the demolition by fire of the

main electrical substation. Co?waissioning recomnenced in October but

was halted again in January 1970 when a four-hour steam failure resulted

in severe damage to equipment d)b§ to freezing.

Commissioning of the plafet with nitrogen gas resumed in April

1970 and continued through unti

the system. By the end of July

and a pressure of 120 Jw/w8 was

was observed during the first

L June when the first n2s was added to

the system had been purged of nitrogen

being maintained. The first enrichment

if August, subsequently the first

drum of reactor grade heavy wait jir was drawn from the Unit on

September 29th, 1970. * '

- 6 -

Production continued until the latter part of October when^the ,

system pressure was increased to 1700'kn/m2 and the operation of the

towers became unstable. In late November one of the first stage towers

was removed from service and it was found that the sieve trays at the'

top of the hot tower had been partially plugged by deposits of iron

sulfide. The deposition occurred at this location because of tha

inverse solubilirry of iron sulfide and was attributed to small con-

centrations of iron in solution in the feedwater. The partial plugging

of the holes created greater than normal differential gas'pressures • ;

across the tray s which ultimately" caused some tray damage. -As a

consequer.'e the total plant was taken out of service December 25th,1970

for traycleaning and repair. 1

Toward"the end of the period whSn the plant was out of service,

the remaining equipment was thoroughly inspected. It was found that

several heat exchangers with Type 304 stainless steel tubes showed an

advanced stage of pitting. Exchangers tubed with Type 316 stainless •

steel did not show any significant signs of deterioration. It was

decided to change 28,400 forty-foot Type 304 tubes to Type 316 stainless

steel tubes. As an interim measure anr in-line- flccculation system was

added to remove iron from the feedwater and immediate steps were taken

for the addition of a ,#iarifier. The exchanger modifications were

completed and the total plant was back in production in May 1971.

During October the plant was again shut down co make the

necessary connections for the clarifier in the feedwater system.

During this shutdown, one 'f.irst stage tower was opened for inspection

and there was no trace of deposit on the hot tower sieve trays. The

clarifierv was put into service, in early December 1971 and was fully

operational by early January 1972. " ' , ' . ^ '

Foam,promoting impurities in the feedwatef are believed,to be -

responsible for intermittent tbwer instability. The clarifier system f

has provided a marked improvement in this situation and work is

currently underway to tp°rovide further improvements. This experience

has demonstrated the need for very high gua3ity''px"ace>';S feedwatar and

has resulted in additional feedvrafcer /treatment system being committed /'

in thede&ign of the Bruce and Glace Bay plants.

Tn the last year eight'total plant.shutdowns, and eleven partial

plant shutdowns were experienced due oto losses °of steam and/or =,

electrical power, • Each of these interruptions resulted *in several

days of production loss due to startup time arid time to re-establish

equilibrium conditions in the, process. Modifications 5to the steam and

elri.irical supply are jibw in, progress to provide a greater continuity

-of these vital services. ' * :

In spite of the lack of "energy continuity, tiie ,fir,st stage, the

second, stage and Finishing Unit have each demonstrated enrichment

capabilitiestin excess of design expectations. In addition £-he thiough-

put capabilities in the second stage, third stage °and Finishing Unit

have also, been demonstrated in excess of-design-, .Throughput's of up to \

90% have been experienced - in the first stages. " '-" '

3RUCE HEAVY WATEft Pl^ANT - "' ' =

The commissioning of the = Enriching UnPitSc is, in progress.'•* Only

minor dalriys have been encountered, gtnerally with some' of the rotating

1 X equipment and valves. The^ utility, systems are('in operation and although

full load cqnditions have not been established, no commissioning delays

are expected. The Finishing Unit has'1 been, commissioned and has -been in

operation for several months upgrading a large quantity of low grade

( 1 — 2%, D2o;j heavy water. This1 Unit h,as ably demonstrated its ability0

^ to saf isfy "..the design criteria* ,. ' , " , ° -

* Although the clarifier system will not be available for ij

comtiiission'irg" until the fall" op 1972, production., is not expected to be

seiriously limited due %o foaming problems because Lake Huron water is

= generally of very good quality! in,this respecti, i . o /(

' \ • ll ' ' f °* Becauae of duplication df,,fche energy supply systems, continuity

' of energy supply «ktid thus the tesign capacity factor should be assured.-

, PRCMPUCTTPW

rThe expected ccjaal^ti

discussed in .this paper

considered *»'• i« guit«

r

ve^prj

fidtikctioh frosv«a^h of the plantson vig*[ 3.;- «he*c estuwteu are

artd' cannot5 be construes as targets.

'''j ^

- 8 - -

Although Canada presently has requirement si for more .heavy water

than we are able to produce/ and is arranging several purchases abroad,

it is expected that domestic production will excejed the, committed

domestic requirements by 1974. ,'

CONCLUSIONS ' ii

\ Although setbacks have been encountered in, the heavy water

production program, the present situation with ea'jsh cf the plants is

such that chere is little uncertainty that the expectations will be

achieved. , jrhe difficult portion of the learning icurve associated with

large scale production plants is now behind us. 'i

* * * * * * f^fr I * *

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"A

tABLEI HEAVY WATER PLANT DATA

LOCATION

OWNER

ENGINEER

OPERATOR

DESIGN CAPACITY

ENERGY REQUIREMENTS

STEAM

ELECTRICAL

CONTRACT PLACEDMl

CONSTRUCTION COMMENCED

CONSTRUCTION COMPLETE ,

UNIT NO. 1

UNIT NO. 2

riRST HEAVY WATER

PORTHAMCaMmYHMP

Point Tiipper, N.S.

CGE

CSE/Lummus

CGE

0.048 Mg/hr

875 x 106 BTU/hr

27 MW

August 196B

November 1966

December 1969

' —

September 1970

i i

_ mucEHwr

'•>•}

Douglat Point, Ont.

AECL "

tummus

Ontario Hyoro

0.096 Mg/hr

'^750 x 106 BTU/hr

68 M *

Jenuarv 1968

March iflfiCi

!•

January 1972

July197|

iii

htovenrtixrt 1972

ECL PLANT

, H

tijladp Bay, N£).i \ . . \i

.--•>' ^ ' I1

Ctouienum of CtntdaI etiBd to AECL

Caniitom/Monrmxc

1

AECL

i

0.063 Mg/hr

326 x 106 BTU/hr

27 MW

RnovnMructionJanuary 1972

1974

o

1976

IJO0O0O 19

FIRST STAGE( 3 IN PARALLEL) A, B & C

SECONO STAGE THIRD STAGE

HOT TOWER COLD TOWE R

HYDROGEN SULPHIDEDEPLETED IN DEUTERIUM

FEED WATER*

COLD SECTION 9O°F

DEUTERIUM ENRICHEDWATER iD2O)

HYDROGEN SULPHIDEENRICHED IN DEUTERIUM

HOT SECTiON 262°F

DEPLETED WATER

HYDROGEN SULPHIDEGAS FLOW =

WATER FLOWi

ENRICHED WATER

¥ TO,, ;FINISHING SECTION

FIGURE 1 DIAGRAMATIC REPRESENTATION OF ENRICHING PROCESS(TYPICAL OF PORT HAWKESBURY AND BRUCE PLANTS)

TOWER WALL LIQUID

'DEUTERIUMTRANSFER REGION

FIGURE 2 DIAGRAMATIC REPRESENTATION OF HjS GAS - HjOLIQUID CONTACTING IN A

GAS FLOW PERFORATEDLATES

T O W E R

.-<*'

T16000-

14000-

12000-

10000-

I 4a| Bnno-

6000-

4000-

2000-

0

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y'g/r It? '4&^^ , ^ ' jgP^V . -r-tTITtni

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FIGURE 4 A VIEW OF BRUCE HEAVY WATER PLANT WITH DOUGLAS POINTNUCLEAR POWER PLANT IN FOREGROUND.

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