Application of nuclear energy to large-scale power and desalting plants

NUCLEAR ENGINEERTI~G ~.~:O DESIGN 4 (1966) 225-232. NORTH-HOLLAND PUBLISHING COMP.. AMSTERDAM

APPLICATION OF NUCLEAR ENERGY TO LARGE-SCALE POWER AND DESALTING PLANTS * ~idney SIEGEL, Simcha GOLAN and J o s e p h A. FALCON A~ v~ics International. Division of North American Aviation, Inc., Canoga Pa~,k. Califor, ia. USA

Received 13 August 1966

There is a currer, t widespread interest in dual-purpose nuclear plants, attr,bu:able to successful developments in both the, lmclear and desalination fiJds. During the past year, it has become clear that nuclear power can :ompete economically with fossil fuel power in many geographical areas. At the same time, parallel strides have been made in the technology and economics ol seawater conversion, particularly in distillation processes. These developments have opened the way for consideration of large-scale plants which can supplement both the electrical energy and fresh water needs of large metropolitan areas near the coast. This paper examines spe2ffic types of nuclear power plants in combination w~th desaltmg plant~ to establish the relative economJ c potential of various heat sources for large-scale dual-purpose application.

1. INTRODUCTION Much has been written recently [1-3] about the economic advantages of power generation and water production in a dual-purpose facility. These advantages r e s u l t p r i m a r i l y f r o m economic gains due to " s c a l e - u p " in plant s i z e and to the improved utilization of energy in a combination plant. Capital cost savings r e s u l t f r o m the low incremental cost for l a r g e r unit heat s o u r c e s and f r o m sharing of common plant facilities such as the condensing and circulating water s y s t e m s . Savings may a l s o result in operation and maintenance by sharing of s u p e r v i s o r y and operating personnel. But perhaps the m o s t i m portant saving attributable to the d u a l - p u r p o s e plant r e s u l t s f r o m improved energy utilization through r e c o v e r y of the heat of condensation which would otherwise be discarded. This latter point can best be illustrated by comparing the energy r e q u i r e m e n t s of single- and d u a l - p u r p o s e plants based on a high t e m p e r a t u r e nuclear heat source. To produce 700 MWe net r e q u i r e s 1700 MWt for a power-only plant. To produce this s a m e block of power and provide .5.56 × 106 B t u / hr of p r o c e s s heat at 40 psia would r e q u i r e 2370 MWt. If the s a m e amount of p r o c e s s heat w e r e to be provided by a s e p a r a t e heat s o u r c e f o r a s i n g l e - p u r p o s e water plant, the heat s o u r c e r a t * Accepted by T.A.Jaeger.

ing would be 1630 MWt. Therefore, the two single-purpose plants r e q u i r e 3330 MWt a s c o m p a r e d with 2370 MWt for the dual-purpose plant. It is thus concluded that both technically and economically the d u a l - p a r p o s e approach has a decided advantage where ~ ready market e x i s t s for the power produced.

2. D U A L - P U R P O S E

PLANT ECONOMICS

2.1. General c o n s i d e r a t i o n s A dual-purpose plant c o n s i s t s of two distinct entities, each providing one end-product; i . e . , the energy plant p r o v i d e s power and the d e s a l t ing plant provides f r e s h water. In the d i s c u s s i o n that follows, the p r e m i s e has been made that the dual-purpose plant is a joint venture of an e l e c t r i c utility and a water agency, with each owning and operating its r e s p e c t i v e facilities in the plant. Another approach which might be c o n s i d e r e d is a sharing of the c o s t s of the pov, e r plant; this is d i s c u s s e d in a lat~.r section. The total cost of owning and operating the energy plant by the e l e c t r i c utility is c o v e r e d by r e v e n u e s f r o m the sale of power and p r o c e s s heat. The unit c o s t of p r o c e s s heat, in ¢/106 Btu, to the water a g e n cy is the controlling f a c t o r in the e c o n o m i c s of f r e s h water production by distillation. F o r the energy plant o p e r a t o r , the p r i c e that he will s e t for ~:he p r o c e s s heat r e f l e c t s the in-

226

S, SIEGEL, S. GOLAN and J. A. FALCON

c r e m e n t a l fuel and capital costs associated with expanding the heat source to provide p r o c e s s heat r e q u i r e m e n t s to the water plant. For all the heat s o u r c e s available for utilization in the energy plant, fuel costs, in ¢/106 Btu, remain e s sentially unchanged as thermal capacity is added for p r o c e s s heat requirements. The incremental unit capital cost, on the other hand, d e c r e a s e s as plant size increases. The relative d e c r e a s e in the unit capital cost is different for various heat sources; e.g., nuclear heat sources have steeper capital cost reduction characteristics than fossil-fueled plants. In comparing two heat sources, cne having a high fuel cost (¢/106 Btu) and a fiat capital cost scaling characteristic and the other a low fuel cost and a relatively steeper capital cost c h a r acteristic, the latter heat source becomes more attractive when the excess capital costs reduce to a value which is more than offset by the difference in fuel cycle cost. This is why nuclear plants generally become rr.~re ~ttractive than fossil plants with larger plant sizes. A similar relationship, although not so marked, exists b e tween lowfuel cost nuclear heat sources and high fuel cost nuclear heat sources. Reactors with low fuel costs are the high-neutron-economy heat sources which generally also have steeper unit capital cost ch~racteristics than r e a c t o r s with a lower neutron economy and hence higher fuel costs. Two such high-neutron-economy heat s o u r c e s are the heavy water, organic cooled reactor (HWR) and the fast breeder reactor'(FBR). Detailed economic analyses of energy plants utilizing these heat s o u r c e s ,-,.re compared in this section. To permit a s s e s s m e n t of the economi~ potential of these concepts, the more fully e s t a b lished light ~p~aterreactor (LWR) is also analyzed and compared with the HWR and FBR on a consistent basis. In the following analysis, the premise has been made that the dual-purpose plant will be committed in the early 70's for on-line s e r v i c e by the mid-70's. The method used in the study is summarized below. Energy plant performance characteristics are set by fixing the power output at the same value for all concepts. The te~al energy plar~ costs and fuel cycle costs are derived for each concept. Inclusion of operation, maintenance, and nuclear insurance expenses permits determination of the cost to own and operate each of the energy plants. Revenues from the vale of power are then ascertained by assigning the same power credit value to all concepts. These revenues subtracted from the cost to own and operate each energy plant establish the level of process heat cost. Optimization of the water plant is conducted, based on

the process heat cost of each ¢lergy plant. Desalting plant performance characteristics, plant design, fresh water output, and cost of fresh water are developed for each energy plant by computer codes. Finally, an analysis is made by comparing the LWR, HWR, and FBR at the same fresh-water production rate. 2.2. Energy plant In setting the rating of the energy plant, consideration was given to providing the maximum block of power that could be extensively b a s e loaded in a large s y s t e m or interconnected grid. Our studies for Southern California, for example, indicato that a block of 750 MWe could be b a s e loaded over its operating lifetime and be c o n s i s tent with s y s t e m r e q u i r e m e n t s . We t h e r e f o r e s e lected a single, b a c k - p r e s s u r e machine of this rating for all concepts. To load the unit in this fashion, the economic incentive must also exist, as determined by the power credit value. The power credit value a s s i g n e d to the e l e c trical producl~ion has been s e t at the m a r k e t value of the power f r o m a 1000-MWe ~best H plant, either fossil or nuclear, that a private utility might install in its s y s t e m in the s a m e point in time. This has been calculated to be 3.0 m i l l s ~ W h , e:~clusive of t r a n s m i s s i o n costs, as shown l a t e r . ~n o r d e r for the dual-purpose plant to be b a s e - l o a d e d , its incremental power c o s t must be at least as low a s the utility's Wbestn plant. Since t~e heat s o u r c e s s e l e c t e d for consideration, the HWR and FBR, have unusually low fuel cycl,~ costs, their incremental power costs a r e evidently low. Hence it is plausible that such plants will in fact have a high capacity factor. With e l e c t r i c a l output for the dual-purpose plants fixed at 750 MWe ( g r o s s ) , a s e r i e s of heat balances was p r e p a r e d for each concept. The r e sults a r e s u m m a r i z e d in table la. The t h r e e b a c k - p r e s s u r e s were a r b i t r a r i l y s e l e c t e d over a sufficiently wide range to establish the r e l a t i o n ships between turbine b a c k - p r e s s u r e and the cost of p r o c e s s heat. As shown later, the optimum b a c k - p r e s s u r e as r e l a t e d to the minimum cost of water is different for each type of energy p!ant. To d e t e r m i n e the cost of p r o c e s s heat f r o m the energy plant, economic p a r a m e t e r s including capital costs, fuel cycle c o s t s , operation and maintenance, and nuclear insurance costs must be established. To facilitate the economic analysis, the capital costs w e r e t r e a t e d as two d i s tinct portions; the nuclear island (steam source), and the turbine island. The nuclear island c o s t range for an LWR was f i r s t estimated by deducting f r o m published p r i c e s for complete p o w e r - o n l y plants the e s t i -

LARCE-SCALE POWER AND DESALTING PLANTS

227

Table 1 Summary of comparative results a. Energy plant characteristics, 750 MWe gross output Reactor type Coolant

LWR

HWR

•,

FBR

..

Throttle steam conditions (psia/OF) Back-pressure (psia) Reactor thermal output (MWt) Net electrical output (MWe) Process steam c onditions (OF)

Organic"

H20 Enr. U 650/Sat

Fuel

'"

Enr. U 800/725

l~-u

10

40

72

10

40

72

10

3]90 7O9

4350 693

5350 680

2830

3670

4360

2000

193

~66

304

710 193

697 266

687 304

707 193

Heat supplied to brine (109 Btu/hr)

8.24

12.2

15.6

6.63

9.36

Sodium

11.6

4.28

2400/1000 40

72

2370 700

2620 695

266

305

5.56

6.42

b. Energy plant costs, $106 Nuclear island

54.2

Turbine island

33.0 87.2

Total energy plant

68.7

81.3

65.9

77.8

86.3

64.0

71.1

76.0

33.0 33.0 1 0 1 . 7 114.3

33.0 98.9

33.0 1"0.8

33.0 129.3

33.0 97.0

33.0 104.1

33.0 109.0

11.3

14.7

17.4

8.5

]0,q

12.1

D20 inventory

c. Cost of process steam, ¢/106 Btu Cost of process steam

12.6

15.4

16.7

7.7

10.8

13.3

d. Water production and costs Water production rate (106 gpd)

180

Water cost (¢/1000 gal)

601

I

I

450

30.1

I

I

28.6

I

I 50

B REAKEVENCOST OF FGR ~ LWR ~ m ; . .

9REAKEVEN COST

~ 2o Z

15

I0

I

15¢0

I

I

I

2000 3000 40(:0 REACTOR RATING (Mval)

I

5000 6000

Fig. l. Comparison cf nuclear island costs versus size for LWR, HWR, and FBR.

570 28.2

150 25.2

300 25.5

450 26.2

100 26.0

180 25.5

240 25.4

m a t e d cost of the c o r r e s p o n d i n g t u r b i n e island. A d j u s t m e n t s were then made to t h e s e LWR nuc l e a r i s l a n d c o s t s to r e f l e c t additional " l e a r n i n g c u r v e a d v a n c e s " and technological i m p r o v e m e n t s expected by the e a r l y 1970's. T h i s LWR c o s t r a n g e is i n d i c a t e d in fig. 1 with the solid line, t o w a r d s the low l i m i t of the r a n g e , p r o v i d ing a r e f e r e n c e cost level for c o m p a r i s o n with the o t h e r e n e r g y s o u r c e s . S i m i l a r e s t i m a t e s p r o p a r e d by our c o m p a n y w e r e made f o r the HWR and the FBR and a r e a l s o indicated in fig, 2. The probable cost l e v e l s of the HWR and F B R w e r e s e t c o n s e r v a t i v e l y t o w a r d the high side of the r a n g e , a s indicated by the r e s p e c t i v e s o l i d l i n e s in fig. I, F o r the turbine i s l a n d , p r i c e s on v a r i o u s b a c k - p r e s s u r e m a c h i n e s were obtained f r o m the t u r b i n e m a n u f a c t u r e r s , In addition, d a t a f r o m a S a r g e n t and Lundy s t u d y [4] were u s e d , Cc,n s i d e r a t i o n was given to the re.generative f e e d - w a t e r equipment and o t h e r a u x i l i a r i e s in the t u r b i n e i s l a n d s s e r v i n g the v a r i o u s heat s o u r c e s , We concluded that the in~talled cost of t u r b i n e i s lands for all b~Lck-pressure m a c h i n e s in the

228

S.SIEGEL, S. GOLAN and J. A. FALCON I"

I

1

/

1

~

I

Table 2 Comparison of adjusted fuel cycle costs.

m lo.F ( . ~

(Enr. U) (a) FBR

~ ~ ~

1 ~'~" "

/

L

~

~

~

~

~

~

2

o

=

cos-r oF Fig. 2. Optimum water costs versus cost of process heat for various top brine temperature levels. range of i n t e r e s t at e i t h e r s a t u r a t e d or high p r e s s u r e / h i g h t e m p e r a t u r e t h r o t t l e conditions was e s s e n t i a l l y the s a m e . T h i s i s p r i m a r i l y due to the elimination of the high c o s t tailend of the turbine which n e g a t e s the p r i c e advantage of a h i g h - t e m p e r a t u r e turbine o v e r a l o w - t e m p e r a t u r e , s a t u r a t e d - s t e a m turbine. B a s e d on the available c o s t data, the total c o s t of the 750-MWe installed turbine island was e s t i m a t e d to be $33,000,000 and was a s s u m e d to be the s a m e f o r all t h r e e plants. The *.~ml capital expenditures for the v a r i o u s 750-MWe e n e r g y plants were a s certained, and a r e n o ~ d in table l b . For the HWR, D20 inventory cost is a l s o listed. E s t i m a t e d equilibrium fuel cycle c o s t s for 1975-1980 operation of the v a r i o u s r e a c t o r s a r e noted in table 2, along with b a s i c ground r u l e s for t h e i r d e t e r m i n a t i o n , table 3. The low i n c r e mental c o s t s of these r e a c t o r s would r e s u l t in a high c a p a c i t y f a c t o r a s mentioned previously. In addition, the advantage of on-line refueling for the HWR will p e r m i t a higher availability than f r o m e i t h e r the F B R or LWR. Accordingly, a 90% capacity f a c t o r was used for the f o r m e r r e a c t o r , and ~5% for the l a t t e r concepts. W:th the capital i n v e s t m e n t and adjusted fuel cycle c o s t s d e t e r m i n e d for each concept, the to_ta[ c o s t to own and o p e r a t e the e n e r g y plants was a s c e r t a i n e d ; operation, maintenance and nuclear insurance c o s t s w e r e e s t i m a t e d at about $ 2.1 × × 10S for all plants. Revenues f o r the delivery of p o ~ e r to the grid were then deducted f r o m the total abnve to a r r i v e at the c o s t of p r o c e s s s t e a m for each e n e r g y plant (table l c ) . Another way of e s t i m a t i n g the economic p o tential of the HWR and F B R s y s t e m s for dualpurpose application is by d e t e r m i n i n g the nuclear

|FabricaUun • r e / pr°cessing / Net fuel buruup /Fuel inventory / Total fuel cycle / COst (rounded) I V 2 ° inventory J D20 + organic |makeup / Adjusted fuel 1 cycle cost

/

13.9'1 [ I I 6.10 ] I 3.61 l I I 113"6 I [ - I I J i - | I I 13.6 I

I

3.39 1.64 1.21 6.2 1.4

7.50 (3.96)C°) 5.61 9.1

1.5 9.1

9.1

(a) Natural uranium may also he used as a fuel in the HWR. Under the same ground rules, the fuel cycle cost of natural uranium in the HWR is 6.4 ¢/106 Btu and the adjusted cost is 10.4 ¢/106 Btu. (b) Net credit. Table 3 Bases for economic evaluation. I) U308 cost ($/Ib) 2) Separative work ($/kg) 3) Fissile Pu (S/g) 4) Low enrichment U cost 5) Fabrication and reprocessing costs 6) Fixed charges on plant capital (% per yr) 7) Fixed charges on fuel investment (% per yr) 8) Fixed charges on D20 investment (% per yr) 9) D20 cost (S/]b) 10) Plant capacity factor (%) Off-line refueling (reference) On-line refueling

8 30 10 1 July, 1962 AEC schedule Based on levels of operations projected for the 1975 to 1980 period 12 10 10 20 * 85 90

Recent announcement by the Canadians indicates a possible reduction in D20 production costs to approximately $14/lb in 1968. island c o s t s which would r e s u l t in the s a m e p r o c e s s heat c o s t s a s f o r the LWR. T h e s e " b r e a k e v e n " c o s t s a r e indicated in fig. 1 by the dashed lines. The wide m a r g i n between t h e s e b r e a k even c o s t s and the p r o b a b l e c o s t s of the HWR and FBR r e p r e s e n t s additional n u c l e a r island c o s t s which t h e s e r e a c t o r s could a s s u m e and still compete with the LWR. 2.3. Desaltingpl~mt The desalting method s e l e c t e d f o r t h i s study

LARGE-SCALE

POWER A N D D E S A L T I N G P L A N T S

is the m u l t i - s t a g e flash distillation p r o c e s s . This p r o c e s s is c u r r e n t l y the m o s t p r o v e n t e c h nologically and is p a r t i c u l a r l y adaptable to l a r g e scale operations. The cost of w a t e r is d e t e r m i n e d by an i t e r a t i r e c o m p u t e r p r o c e s s which e c o n o m i c a l l y h a l a n c e s capital i n v e s t m e n t , pumping power, c h e m i c a l t r e a t m e n t , O and M, and p r o c e s s heat costs. A fixed c h a r g e r a t e of 7% was applied to the c a p ital i n v e s t m e n t of the desalting plant a s being r e p r e s e n t a t i v e of public agenc5 ownership. The c o m p u t e r p r o g r a m s o l v e s the m a t e r i a l and ene r g y b a l a n c e s , s e t s the w a t e r plant design p a r a m e t e r s , and d e t e r m i n e s the f r e s h w a t e r cost and production r a t e . Unit c o s t data and the heat t r a n s f e r c o r r e l a t i o n employed in the p r o g r a m were obtained f r o m a r e c e n t study p e r f o r m e d f o r the OSW and the AEC [5]. The r e s u h s of the w a t e r plant optimization studies a s a function of b a c k - p r e s s u r e a r e s u m m a r i z e d g r a p h i c a l l y in fig. 2 by the dashed lines. T h e s e c o r r e l a t i o n s a r e independent of the s o u r c e of p r o c e s s heat; they m e r e l y denote the lowest cost w a t e r f o r a given p r o c e s s h e a t cost. The w a t e r c o s t s r e f l e c t a d j u s t m e n t s in only c h e m i c a l t r e a t m e n t and e v a p o r a t o r s t r u c t u r e c o s t s a s r e lated to the s p e c i f i c top brine t e m p e r a t u r e s . The s a m e c o n d e n s e r s u r f a c e m a t e r i a l , c o p p e r alloy, was a s s u m e d f o r all b r i n e t e m p e r a t u r e s ; this m a y be c o n s e r v a t i v e for the low b a c k - p r e s s u r e c a s e , and o p t i m i s t i c for the high b a c k - p r e s s u r e c a s e . It is significant to note that b a s e d on the heat t r a n s f e r and c o s t data u s e d in this a n a l y s i s t h e r e is little to be gained in going to b a c k - p r e s s u r e s higher than 40 psia. T h e s e w a t e r cost c o r r e l a t i o n s w e r e developed on the b a s i s of a daily production of around 180 million glm. O u r studies indicate, h o w e v e r , that within the 100- to 800-million gpd r a n g e these c o s t s v a r y by l e s s than 4%, and hence a r e r e p r e sentative o v e r t h i s wide range. S u p e r i m p o s e d on fig. 2 a r e the r e s p e c t i v e p r o c e s s heat c o s t s ,

229

table l c , for each r e a c t o r concept at the c o r r e sponding b a c k - p r e s s u r e s a s denoted by the solid lines. This figure then r e p r e s e n t s the o p t i m u m w a t e r c o s t s a s s o c i a t e d with each of the 750 MWe e n e r g y plants at a n y - h a c k - p r e s s u r e and" c o s t of p r o c e s s heat. T h e s e r e s u l t s , r e p r e s e n t e d t y the c r o s s o v e r points between the dashed and solid l i n e s , a r e s u m m a r i z e d in table ld, along with the c o r r e s p o n d i n g o p t i m u m water production r a t e s . It is noted f r o m table ld that w a t e r p r o duction rate~ v a r y c o n s i d e r a b l y between the v a r ious concepts. A m o r e meaningful c o m p a r i s o n is to d e t e r m i n e the o p t i m u m cost of w a t e r for each e n e r g y plant at the s a m e w a t e r production r a t e . T h e r e f o r e , fixed w a t e r plant outputs of 180 and 300 million g a i / d a y w e r e a r b i t r a r i l y s e l e c t e d for c o m p a r i s o n . The r e s u l t s of this a n a l y s i s a r e l i s t e d in table 4 and a typical heat balance for the r e f e r e n c e HWR t h e r m a l cycle is shown in fig. 3. Utilization of both the HWR and F B R for d u a l - p u r p o s e application a p p e a r s a t t r a c t i v e . L o n g - t e r m c o n s i d e r a t i o n s affecting t h e s e s y s t e m s f u r t h e r influence the selection of the heat s o u r c e . This is d i s c u s s e d m o r e fully l a t e r . The foregoing s t u d i e s w e r e b a s e d on p r i v a t e utility ownership of the e n e r g y plant with fixed c h a r g e s of 12%, and w a t e r agency o w n e r s h i p of the desalting plant with fixed c h a r g e s of 7%. Ano t h e r possible a r r a n g e m e n t is one in which the utility and the w a t e r a g e n c y jointly own the uuc l e a r island, the utility paying for the portion of the plant which would be r e q u i r e d under p o w e r only conditions. The w a t e r agency p a y s the inc r e m e n t a l i n v e s t m e n t c o s t s hi the e n e r g y plant and applies its 7q~ fixed c h a r g e r a t e to that. The cos t- of p r o c e s s heat is d e t e r m i n e d f r o m the inc r e m e n t a l fuel c o s t s in the nuclear island. "With such a joint a r r a n g e m e n t , water c o s t s a r e dec r e a s e d about 10%, due to the l o w e r fixed c h a r g e s on that portion of the n u c l e a r island owned by the water agency.

Table 4 Optimum cost of water at 750 lVlWe rating.

Energy plant Water plant output (106 gpd) Optimum back-pressure (psia) Reactor th~.rmal rating (MWt) Process heat to brine (109 Btu/hr) Cost of heat to brine (¢/106 Btu) Cost of fresh water

(C/ZOO0gal.)

* Reference HWR plant

HWR

LWR 180 10 3190 8.24

300 23 3710 9.65

12.6

13.9

30

29

180" 15 3000 7.14 8.2 25

FBR

300 40 3670

180 40 2370 5.56

300 72 2620 6.42

10.8

10.7

12,1

25

26

28

9.36

230

S. SIEGEL, S. GOLAN and J. A. FALCON Table 5 "Best" power-only plant generation costs. R e a c t o r type Net e l e c t r i c a l output (MWe) R e a c t o r power (MWt) Capacity factor Capital cost (106 $)

HWR-enr.-U 10O0 3000 0.90

LWR

1000 3200 0.85

Nuclear island

54.4 51.0

Turbine plant (ocean site)

+

_

+ 3.0 66.0 _ 9.0 51.0

9.6 3.2

105 + 9.6 3.2

Total

117

-

+ 3.0 - 9.0

FOSSIL 1000 2500 0.90

FBR 1000 2400 0.85 + 4.8 72.0 _ 14.4 48.0 120 + 4.8 14.4

90

+ 12. for D20 Annual costs (106 $/yr) 12.6

Capital D20 inventory Fuel inventory Fuel expense O and M + nucl. ins. D20 + organic makeup

2.9 8.1 ~.1

T,Jlal Mills/kWh

25.7 3.5

2005

14.0 1.2 1.0 4.1 2.1 1.2

14.4

10.8

3.4 2.2 2.1

10.1 1.8

23.6 3.0

22.1 3.0

22.7 2.9

9,441,400" BOOP ~'25F

- , ,m~jJ~'~ ....

-

3

P - - 141P85.4R , ~

OUTPUT = 750,360 kw GENERATOR 8 MECHANICAL LOSSES = 11,910 kw

L l

,4,,P

BRINE HEATERS 14,5P 7,142 x 10`9 B , . r . , . , , m . . . .518h ..439,000. 1212H

TD

LEGENO P = PRESSURE (psla) F -- TEMPERATURE PF) H, h : ENTHALPY OF STEAM OR L,QUID I Blu lib) * : FLOW (Ib/hr)

I

0Q ~TD

6131

- ~ 16,2005 181,Ih 5= ~TD

5* ~ T D

39o,

~1:=.c9,901,0005 ~ 3(' 434~800~ 362P 334,4h

REACTOR POWER = 3000 Mw POWER TO COOLANT = 2865 Mw GENERATOR OUTPUT = 750,380 kw PLANT AUXILIARIES = 421980 kw NET PLANT OUTPUT = 707.,380 kw HEAT TO BRINE HEATERS = 7t 142.x 109 81u/hr

/,h= 3,1 BOILE~ FEEO ~]MP

Fig. 3. Heat balance for reference HWR plant.

MAKEUP 16,;'00 5 58h

936,400: 249,3F 217,8h

LARGE-SCALE POWER AND DESALTING PLANTS 2.4. "Best" power-only plant Development of nuclear island and fuel cycle costs for the various r e a c t o r s p e r m i t s a ready evaluation of the "best" power-only plant that a utility might install in its system in the e a r l y to mid-70's. We have selected a 1000-net MWe unit as being r e p r e s e n t a t i v e of the size of machine installed at that time. Fossil fuel costs of 15¢/ 106 Btu were used. Capacity f a c t o r s of 85% for off-line refueling and 90% for on-line refueling nuclear plants were used. To make the c o m p a r i son equitab!e, a capacity factor of 90% was also assigned to the fossil plant. T h e r e s u l t s are s u m m a r i z e d in table 5, and we have c(~ncluded that the "best" plant total e n e r g y c¢.st would be 3.0 rufUs/kWh. The use of 15¢ fuel for the fossil plant implies an inland location at or near the source of fuel, at least as far as Southern California is concerned. The effect of t r a n s m i s sion costs to a coastal load center was not considered.

3. LONG-TERM CONSIDERATIONS The preceding discussion c e n t e r e d around the economic conditions and r e q u i r e m e n t s as related to plants committed by the e a r l y 1970's. This leads to cons.~deration of dual-purpose plan*~ sizes, 750-MWe, 180 million gpd, expected for that period. Also, fuel cycle costs w e r e based on uranium ore and plutonium price levels anticipated in that period. The three f a c t o r s , size, uranium ore, and plutonium prices, a r e significant l o n g e r - t e r m considerations which influence the selection of the heat source as follows. 1) It is expected that by 1985 a typical dual-purpose plant v~ould be r a t e d at 1500 MWe, with f r e s h - w a t e r production outputs of f r o m 300 to 600 million gpd. The nuclear heat s o u r c e serving this complex would be r a t e d from 5000 to 7500 MW t h e r m a l depending on the r e a c t o r type. 2) A r i s e in uranium ore p r i c e s as the limited low cost r e s e r v e s become depleted is also expected. Based on r e c e n t e s t i m a t e s of our available uranium r e s o u r c e s and anticipated future demands, uranium ore prices a r e likely to inc r e a s e above $8/lb after 1980, and may r e a c h the $16/lb level by late 1990's [6]. 3) The plutonium value of $10/8 used in this study is based on its n e a r - t e r m relative (to U-235) value for r e c y c l e into t h e r m a l r e a c t o r s . Our studies [6] and others [7] indicate that successful development of fast b r e e d e r s will inc r e a s e the relative value of plutonium by 30% to perhaps 80%. This will result f r o m the demand

231

Table 6 Long-term considerations Size extrapolation

Rising uranium prices

HWR FBR LWR

HWR/FBR LWR

Increased I p!utonium value

J

ItWR LWR FBR

t t

for plutonium exceeding the supply in an expanc'~ing nuclear economy. A ranking of the r e f e r e n c e energy plants r e l ative to these l o n g - t e r m considerations is shown in table 6. It is noted that these long-term considerations all favor the HWR. Because of its specific design features, its on-line refueling capability, and its low fuel cycle cost, the HWR is particularly adaptable to l a r g e r r e a c t o r sizes. The excellent neutron economy of the HWR makes it highly insensitive to rising ore prices. Also, because of its high neutron economy, the HWR is an excellent plutonium producer, thereby greatly benefiting by an ~increase in plutonium value. The latter two considerations a r e of particular i m portance in comparing the HWR with the LWR, sin~.~ rising ore p r i c e s and plutonium values both i n c r e a s e the economic advantage of the qWR c o m p a r e d with the LWR. FBR energy costs inc r e a s e with r i s e in Pu price because fuel invent o r y charges exceed the credit from sale of bred plutonium.

4. CONCLUSIONS 1) L a r g e - s c a l e seawater plants when integrated with large .mclear power stations will result in lower water costs than either those integrated with conventional power plants or those with heat supplied b:, nuclear single-purpose p r o c e s s - h e a t plants. 2) The HWR and the FBR offer the g r e a t e s t n e a r t e r m potential for combined l a r g e - s c a l e production of power and f r e s h water. This is attributable p r i m a r i l y to the low fuel cycle costs coupled with favorable scaling economics anticipated for these r e a c t o r s . In addit'.~n, longer t e r m considerations favor the HWR as the best s o u r c e of ene r g y for such application.

ACKNOWLF OGMENTS The authors wish to acknowledge the efforts of our c o - w o r k e r s ; J . A . H e s s l e r for his c o n t r i -

232

S. SIEGEL, S. GOLAN 8nd J.A. FALCON

butions to development of the w a t e r plant c o m p u t e r p r o g r a m ; and G.A. Schneider, who p r e p a r e d the s e r i e s of heat b a l a n c e s .

REFERENCES [1] P. R. Hammond, Large reactors may distill sea water economically, Nucleonics 20 (1962) 45. [2] S. Baron, Economics of reactors for power and desalination, Nucleonics 22 (1964) 67. [3] J. T. Ramey, J.K. Cart and R.W. Ritzmann, Nuclear reactors applied to water desalting, Paper 220, Third United Nations International Conference on the Peaceful Uses of Atomic Energy, Geneva, September 1964.

[4] Sargent and Lundy, Large condensing and non-condensing turbine plant study, Report SL-2158 (1964), prepared for Oak Ridge National Laboratory. [5] Catalytic Construction Company and Nuclear Utility Services, Inc., A study of desalting plants (15 to 150 Mgd) and nucIear power plants (200 to 1500 MWt) for combined water and power production (1964), prepared for U.S. Department of Interior, Office of Saline Water and AEC, Division of Reactor Development. [6] S.Golan, Optimum nuclear fuel resource utilization, presented at American Power Conference, Chicago, Illinois, 28 April 1965. [7] H, A. Wagner, Plutonium as a fuel: economic and technological aspects, presented at the 1964 Annual Conference, Atomic Industrial Forum, 30 November to 3 D~cember, San Francisco, California.