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Contract No. W-7405-eng-26
W C T O R DIVISION
ESTIMATED COST OF ADDING A THIRD SALT-CIRCULATING SYSTEM FOR CONTROLLING TRITIUM MIGRATION IN THE lOOO-MW( e ) MSER
Roy C. Robertson
JULY 1971 This report was prepared as an accriunt of work sponsored by the United States Government. Neither the United States nor the United States Atomic Energy Commission, nor any of their employees, nor any of their contractors, subcontractors, or their employees, I makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness or usefulness of any information, apparatus, product or process disclosed, or represents that its use would not infringe privately owned
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OAK RIDGE NATIONAL LABORATORY Oak Ridge, Tennessee Operated by TINION CARBIDE CORPORATION for the U . S . ATOMIC ENERGY COMMISSION
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W
iii CONTENTS Page Abstract ---------------------------------------------------------Summary and Conclusions --------------------______c_____________----------------__---------------------------------1. Introduction 2. Description of MSBR Modified with Third Loops ----------------3. Heat Transfer Equipment --------------------------------------4.
Salt-Circulating
5.
Salt
Inventory
pmps ____________________-------------------Costs ------------------------------------------
1 2
5 7 9 21
24
LIST OF TABLES Table 1.
Table Table Table Table Table Table Table
11
4.
Summary of Cost Items Affected by Modifying MSBR Reference Design to Include Third Salt-Circulating Loops -_-_-----------------------------Selected Properties of the MSBR Molten Salts -----------Material Costs Used in Estimates -------------------_---Primary Heat Exchangers _---_-----------_----------------
5. 6. 7. 8.
Secondary Heat &changers ------------------------------Steam Generators ---------------------------------------Steam Reheaters ---------------------------------Reheat Steam Preheaters ---------------------------------
17 19
2.
3.
Table 9. Table 10. Table 11. Table 12. Table 13. Table 14.
-------
Revised Reference Design Costs for Heat Transfer Equipment, in $1000 ---------------__-_---------
3 12
13 15
20 21
Estimated Transfer
Direct Cost of Installed Heat Equipment per Square Foot of Surface ---------
22
Estimated Installed
Design Data and Allowances Costs of Salt-Circulating
23
for Pumps -------------
Estimated Pumping Power Requirements and Worth of Improved Efficiency of Modified MSBR Cycle --------23 _________________________ 25 Estimated Salt Inventory Costs Estimated Volume of LiF-BeF, Salt in Secondary System of Modified Ivj,Cjm____-__________________________ 26 LIST OF FIGURES
Fig.
1.
Schematic Flowsheet of lOOO-MW(e) MSBR Power Station as Modified with Addition of Third Loops to Trap 3H -------------____-_---------------------
8
iv LIST OF FIGURES (Contd. ) I
Page Fig. 2.
MSBR Reactor C e l l Layout I n d i c a t i n g P o s s i b l e Location for Secondary Heat &changer and pWnp _____________________________c__________---~.---10
ESTIMATED COST OF ADDING A THIRD SALT-CIRCULATING SYSTEN FOR CONTROLLING TRITIUM MIGRATION I N THE lOOO-MW( e ) MSBR Roy C. Robertson
ABSTRACT C o n t r o l l i n g tritium migration t o t h e steam system of t h e 1000-MW(e) r e f e r e n c e design MSBR power s t a t i o n by i n t e r p o s i n g a KN03-NaNOa-NaN03 s a l t - c i r c u l a t i n g system t o chemically t r a p t h e tritium would add about $13 m i l l i o n t o t h e t o t a l of $206 m i l l i o n now estimated as t h e c o s t of t h e r e f e r e n c e p l a n t i f Hastelloy N i s used t o c o n t a i n t h e 'LiF-BFa s a l t employed t o t r a n s p o r t h e a t from t h e f u e l s a l t t o t h e n i t r a t e - n i t r i t e salt, and about $10 m i l l i o n i f Incoloy could be used. The major expenses a s s o c i a t e d with t h e modification a r e t h e c o s t s of t h e a d d i t i o n a l h e a t exchangers ($9 m i l l i o n ) , t h e a d d i t i o n a l pumps ($5 m i l l i o n ) , and t h e 7LiF-BeFa inventory ($4.8 m i l l i o n ) . Some of t h e expense i s o f f s e t by e l i m i n a t i o n of some equipment from t h e feedwater system ($2 m i l l i o n ) , through use of less expensive m a t e r i a l s i n t h e steam g e n e r a t o r s and r e h e a , t e r s (about $2 m i l l i o n ) , and through an improved thermal e f f i c i e n c y of t h e p l a n t (worth about $1m i l l i o n ) . I n a d d i t i o n t o a c t i n g as an e f f e c t i v e tritium t r a p t h e t h i r d c i r c u l a t i n g system would make a c c i d e n t a l mixing of t h e f u e l and secondary s a l t s of l e s s consequence and would s i m p l i f y s t a r t u p and o p e r a t i o n of t h e MSBR. A s i m p l i f i e d flowsheet f o r t h e modified p l a n t , a c e l l l a y out showing l o c a t i o n of t h e new equipment, p h y s i c a l prope r t i e s of t h e f l u i d s , design d a t a and c o s t estimates f o r t h e new and modified equipment a r e presented.
-
*MSBR + *ritium + * c a p i t a l c o s t + conceptual design + loop + coolants + h e a t exchangers + pumps + power c o s t s + f u e l - c y c l e c o s t s + steam system.
KFY WORDS
2
SUMMARY AND CONCLUSIONS
Y
C o n t r o l l i n g tritium migration t o t h e steam system of t h e 1000-MW(e) r e f e r e n c e design MSBR power s t a t i o n by i n t e r p o s i n g s a l t - c i r c u l a t i n g loops t o chemically t r a p t h e tritium would add
4 t o 6$ t o
the t o t a l plant cost.
The n e t i n c r e a s e i n c a p i t a l c o s t of t h e p l a n t , i n c l u d i n g i n d i r e c t c o s t s ,
i s about $13 m i l l i o n if H a s t e l l o y N i s used t o c o n t a i n t h e 7LiF-BeF,
s a l t employed as t h e h e a t t r a n s p o r t f l u i d i n t h e secondary system, and about $10 m i l l i o n i f Incoloy could be used.
These i n c r e a s e s would apply
t o a c o s t f o r t h e r e f e r e n c e design p l a n t now estimated a t about $206 m i l l i o n (based on e a r l y
1970 c o s t s ) .
Addition of t h e l o o p s would i n -
c r e a s e t h e power production c o s t s by 0 . 2 4 . 3 mills/kWhr, making t h e t o t a l c o s t about 5.5 mills/kWhr
.
A s shown i n t h e c o s t summary, Table 1, t h e major p o r t i o n of t h e c o s t of modifying t h e design i s due t o t h e a d d i t i o n a l h e a t exchangers and pumps r e q u i r e d , and t o t h e r e l a t i v e l y high c o s t of t h e 7Li-bearing secondary s a l t .
There were a l s o i n c r e a s e s i n t h e c o s t of t h e primary
h e a t exchangers and i n t h e f u e l - s a l t inventory.
However, t h e added
t h i r d loops use a n i t r a t e - n i t r i t e h e a t t r a n s p o r t s a l t which permits savings i n t h e material c o s t s i n t h e steam g e n e r a t o r s and r e h e a t e r s . Use of t h i s s a l t a l s o permits r e d u c t i o n s i n t h e feedwater and cold r e h e a t steam temperatures, and through changes i n t h e steam system flows h e e t and t h e a u x i l i a r y e l e c t r i c load, produces a r e d u c t i o n of c o s t s e q u i v a l e n t t o a p l a n t investment of about $800,000. C r e d i t f o r t h e s e savings was taken i n t h e n e t c o s t s mentioned above.
In a d d i t i o n t o s e r v i n g as an e f f e c t i v e tritium t r a p , t h e t h i r d loops o f f e r o t h e r important advantages over t h e r e f e r e n c e design.
These
a r e f e a t u r e s which, i n general, could not have c o s t c r e d i t s assigned. For example, t h e s i m i l a r i t y of t h e f u e l and secondary s a l t s makes mixing due t o l e a k s i n t h e primary h e a t exchanger of f a r l e s s consequence t h a n i n t h e r e f e r e n c e design.
S t a r t u p and o p e r a t i o n of t h e MSBR would be
s i m p l i f i e d because of changes t h a t could be made i n t h e steam system flow s h e e t ,
3 Table 1.
Summary of Cost Items Affected by Modifying MSBR Reference Design t o Include Third S a l t - C i r c u l a t i n g Loops ( i n $1000) Rev. Reference Design MSBR
A.
Modified MSBR with Third Loops
With H a s t e l l o y N secondary system Revised equipment : Primary h e a t exchangers (see Table Steam g e n e r a t o r s (see Table Steam r e h e a t e r s ( s e e Table
4)
6)
7)
$8,660 7,230 1,565
$ 9,880
6,192 1,216
Coolant s a l t pumps ( s e e Table 11)
4,400
2,750
Coolant s a l t piping allowance
1,900 800
1,500
Coolant s a l t d r a i n tank Coolant s a l t inventory c o s t Auxiliary b o i l e r allowance
500
800 135
3,000
2,500
New equipment : Secondary h e a t exchanger ( s e e Table
5)
6,883
Secondary pumps (see Table 11)
3,800
Secondary s a l t d r a i n tank
800
Secondary system piping allowance
375
Accessory e l e c t r i c a l f o r secondary system
200
Eliminated equipment: Reheat steam p r e h e a t e r s (see Table 8) Pressure-booster pumps Mixing chambers T o t a l d i r e c t c o n s t r u c t i o n c o s t , i n $1000 Difference i n d i r e c t c o n s t r u c t i o n c o s t s Difference i n t o t a l c o s t with added i n d i r e c t c o s t s of 33$ 7LiF-BeF inventory c o s t ( s e e Tables and 147
13
Credit f o r r e s a l e value of 7LiF-BeFa Credit f o r improved p l a n t e f f i c i e n c y ( s e e Table 1 2 ) Net estimated c a p i t a l c o s t of adding t h i r d loops
1,056 650 80
$29,841
$37,031 $7,190 $9,563 4,800 -239 -817 $13,300 ( continued)
4 Table 1 (continued) Rev. Reference Design MSBR
mills/kWhr
Changes i n power production c o s t :
13.7% FC
Net c o s t of adding t h i r d loops, a t LiF-&Fa
inventory, a t 13.2% FC
C r e d i t f o r r e s a l e LiF-&Fa,
+ 0.187 -t
a t 13.2% FC
13.7% FC
Credit f o r improved e f f i c i e n c y , a t
0.090
- 0.005 - 0.015
+
Increase i n f u e l - c y c l e c o s t
0.013
+ 0.27 mills/kWhr
Net i n c r e a s e i n c o s t of power
B.
Modified MSBR with Third Loops
With Incoloy secondary system
All items i n modified MSBR not a f f e c t e d by use of Incoloy r a t h e r t h a n H a s t e l l o y N i n secondary c i r c u l a t i n g loop, from P a r t A, above.
$ 19,893
Cost of items i n which Incoloy i s s u b s t i t u t e d f o r H a s t e l l o y N:
4)
Primary h e a t exchangers, ( s e e Table Secondary s a l t p i p i n g allowance
225
Secondary h e a t exchangers ( s e e Table
5)
Cost of r e v i s e d r e f e r e n c e design, from P a r t A Difference i n d i r e c t c o n s t r u c t i o n c o s t s Difference i n t o t a l c o s t with i n d i r e c t c o s t s of 33% added 7LiF-BeFa inventory c o s t ( s e e Tables
13 and 14)
Credit f o r improved p l a n t e f f i c i e n c y ( s e e Table 12) Net estimated c o s t of adding t h i r d loops
4,800 -239 -817 $ 10,200 mills/kWhr
Changes i n power production c o s t .
13.7% FC
LiF-BFa inventory, a t 13.2% FC Credit f o r r e s a l e LiF-&Fa,
5,879 $ 34,658 -29,841 $ 4,817 $ 6,407
C r e d i t f o r r e s a l e value of ?LiF-BeF,
Net c o s t adding t h i r d loops, a t
8,661
a t 13.2% FC
C r e d i t f o r improved e f f i c i e n c y , a t Increase i n f u e l - c y c l e c o s t Net i n c r e a s e i n c o s t of power.
13.7% FC
+ 0.125 + 0.090
- 0.005 - 0.015 + 0.013 + 0.21 mills/kWhr
5 1.
INTRODUCTION
T r i t i u m formed i n t h e MSBR f u e l s a l t must be prevented from reaching t h e steam system.
The problem i s d i f f i c u l t because of t h e r e l a t i v e ease
w i t h which hydrogen d i f f u s e s through most metals a t MSBR operating tem-
peratures.
S t u d i e s are being made a t ORNL of s e v e r a l d i f f e r e n t methods
of tritium c o n t r o l ; of these, t h e i n t r o d u c t i o n of a t h i r d s a l t - c i r c u l a t i n g system t o chemically t r a p t h e tritium between t h e secondary s a l t and t h e
steam system i s t h e only one w e l l w i t h i n p r e s e n t technology and, on t h e b a s i s of p r e s e n t knowledge, o f f e r s assured confinement of t h e tritium.
It i s p o s s i b l y one of t h e most expensive of t h e c o n t r o l methods being cons i d e r e d , however, and r a i s e s t h e question as t o whether i t s use would add p r o h i b i t i v e l y t o t h e c o s t of a molten-salt r e a c t o r power s t a t i o n . This study e v a l u a t e s t h e v a r i o u s c o s t f a c t o r s involved i n adding t h e t h i r d s a l t - c i r c u l a t i n g system t o t h e 1000-MW(e) MSBR r e f e r e n c e design
described i n
0RNL-4541.1
i n that report.
The c o s t e s t i m a t i n g methods follows t h o s e used
The c o s t s of modifying t h e r e f e r e n c e design i n c l u d e t h e
c a p i t a l c o s t of t h e e x t r a equipment, t h e s a l t i n v e n t o r i e s , and a l s o r e f l e c t t h e c o s t e f f e c t s of t h e new designs f o r t h e h e a t t r a n s f e r equipment made necessary by t h e use of h e a t t r a n s f e r f l u i d s d i f f e r e n t from t h o s e used i n t h e r e f e r e n c e concept.
(The c a l c u l a t i o n s f o r t h e new and modified heat
exchangers were made by C. E. Eettis e t a l . , u s i n g e s s e n t i a l l y t h e same computer programs as were used i n t h e r e f e r e n c e d e s i g n . )
The c o s t e s t i -
mates a l s o t a k e c r e d i t for t h e equipment n o t needed i n t h e feedwater system of t h e modified p l a n t and f o r t h e improved thermal e f f i c i e n c y of t h e s t a t i o n , as explained below. The r e f e r e n c e MSBR design u s e s c i r c u l a t i n g sodium f l u o r o b o r a t e , NaF-NaBF4, t o t r a n s p o r t heat t o t h e steam g e n e r a t o r s and r e h e a t e r s , whereas t h e modified design u s e s a n i t r a t e - n i t r i t e h e a t t r a n s f e r s a l t , KN03-NaN02-
NaNO,
(known commercially as "Hitec"), t o h e a t t h e steam equipment.
has f i v e important advantages:
This
(1) any hydrogen d i f f u s i n g i n t o t h e s a l t
'Roy C. Robertson e t a l . , Conceptual Design of a Single-Fluid MoltenS a l t Breeder Reactor, 0-541 (May 1971).
6 would combine w i t h t h e oxygen and subsequently be drawn o f f as steam and c o l l e c t e d , forming an e f f e c t i v e tritium t r a p ; ( 2 ) t h e s a l t i s not corros i v e t o l e s s expensive m a t e r i a l s of c o n s t r u c t i o n , allowing Incoloy 800, o r a similar m a t e r i a l , t o be s u b s t i t u t e d f o r t h e H a s t e l l o y N used i n t h e r e f e r e n c e design; ( 3 ) i t s low m e l t i n g temperature of 2 8 8 " ~permits u s e of conventional feedwater and cold r e h e a t temperatures i n t h e steam system and e l i m i n a t e s t h e need f o r t h e r e h e a t steam p r e h e a t e r s , t h e p r e s s u r e b o o s t e r pumps and mixing chambers used i n t h e r e f e r e n c e design;
(4)
s t a r t u p of t h e system i s s i m p l i f i e d and t h e a u x i l i a r y b o i l e r probably does not need t o be a s u p e r c r i t i c a l - p r e s s u r e u n i t as i n t h e r e f e r e n c e p l a n t ; and ( 5 ) t h e s a l t has a low c o s t of only about 15 c e n t s / l b .
The
s a l t does not r e a c t exothermically with water and it has good flow and heat t r a n s f e r properties. The modified design would use a 7LiF-BeF, s a l t t o t r a n s p o r t h e a t from t h e f u e l s a l t t o t h e n i t r a t e - n i t r i t e s a l t .
With t h e exception of
t h e uraniam and thorium components, t h i s s a l t i s t h e same as t h e f u e l s a l t , and t h u s a l e a k i n t h e primary h e a t exchanger would be of f a r less consequence t h a n i n t h e r e f e r e n c e design where d i s s i m i l a r s a l t s would mix. The 7LiF-BeF, i s not c o r r o s i v e t o m a t e r i a l s l e s s expensive t h a n H a s t e l l o y N, provided t h a t no moisture i s p r e s e n t .
One c o s t e s t i m a t e i n t h i s study
has been made u s i n g H a s t e l l o y N f o r t h e secondary system and another using Incoloy.
Due t o t h e l i t h i u m - 7 content, t h e c o s t of t h e s a l t i s
r e l a t i v e l y high
--
about $12/1b.
I t s r e s a l e value a t t h e end of t h e
30-year p l a n t l i f e has been taken i n t o account, although t h e e f f e c t i s not great. The r e f e r e n c e MSBR design c o n s i s t s of a s i n g l e r e a c t o r supplying h e a t t o f o u r primary c i r c u l a t i n g loops, each c o n t a i n i n g a s a l t - c i r c u l a t i n g pump and a h e a t exchanger.
The c o o l a n t - s a l t system c o n t a i n s f o u r loops,
w i t h each c o n t a i n i n g a s a l t - c i r c u l a t i n g pump, f o u r steam g e n e r a t o r s and two r e h e a t e r s .
This arrangement was not a l t e r e d i n t h e modified design,
although t h e r e was some adjustment of t h e temperatures.
The i n t e r p o s e d
s a l t - c i r c u l a t i n g system would c o n s i s t of f o u r loops, each c o n t a i n i n g a c i r c u l a t i n g pump and a h e a t exchanger. adopted.
The following terminology has been
7
LiF-&Fa t o KN03-NaN02-NaN03 exchanger
---
KN03-NaNOo-NaN03 t o steam exchangers
--
Fuel s a l t t o 'LiF-BeF2
h e a t exchanger
---
F u e l - s a l t c i r c u l a t i n g pump LiF-&Fa
c i r c u l a t i n g pump
KN0,-NaNOa-NaN03
c i r c u l a t i n g pump
--
Primary h e a t exchanger Secondary h e a t exchanger Steam generator o r steam r e h e a t e r Primary pump Secondary pump T e r t i a r y pump
This study i s p r i m a r i l y concerned with e v a l u a t i n g t h e c o s t e f f e c t s of adding t h e t h i r d s a l t - c i r c u l a t i n g loops.
The concept was not c a r r i e d
f u r t h e r t h a n t o i n d i c a t e general f e a s i b i l i t y and t o provide a b a s i s for cost estimates.
No e f f o r t was made toward optimization.
I n comparing t h e c o s t of t h e MSBR modified with t h e t h i r d loops t o t h e r e f e r e n c e design c o s t e s t i m a t e s , it was necessary t o make some r e v i s i o n s t o t h e l a t t e r as r e p o r t e d i n ORNL-4541.
The h e a t t r a n s f e r equip-
ment design d a t a haveundergone two r e l a t i v e l y r e c e n t r e v i s i o n s .
The
f i r s t was made i n time t o be t a b u l a t e d with t h e design d a t a i n t h e l a t e s t
d i s t r i b u t e d d r a f t of t h e r e p o r t , b u t , because of t h e e x t e n s i v e changes r e q u i r e d and t h e f a c t t h a t a t t h e time t h e i n f l u e n c e on c o s t s appeared t o be s m a l l , t h e c o s t e s t i m a t e s were not a d j u s t e d accordingly.
The
second r e v i s i o n , which a p p l i e d only t o t h e primary h e a t exchanger, was made j u s t i n time f o r t h e d a t a t o be changed before t h e r e p o r t was p r i n t e d , b u t , again, t h e c o s t e s t i m a t e s could not be r e v i s e d .
All of
t h e r e v i s i o n s tended t o i n c r e a s e c o s t s , however, and when t h e c o s t e s t i mates were r e v i s e d i n t h i s study it was found t h a t i n aggregate t h e y amounted t o about $4 m i l l i o n , i n c l u d i n g t h e i n d i r e c t charges. c a p i t a l c o s t of t h e r e f e r e n c e design MSBR i s t h u s about r a t h e r t h a n t h e $202 m i l l i o n given i n on t h e e a r l y 2,
1970 value
The t o t a l
$206 m i l l i o n
ORNL-4541. Both amounts a r e based
of t h e d o l l a r .
DESCRIPTION OF MSBR MODIFIED WITH THIRD LOOPS
A s i m p l i f i e d flowsheet f o r t h e 1000-MW(e) MSBR s t a t i o n as modified t o include t h e t h i r d s a l t - c i r c u l a t i n g loops i s shown i n Fig. 1. It can be noted t h a t t h e temperatures have been a d j u s t e d from t h o s e used i n t h e r e f e r e n c e design and t h a t t h e r e were corresponding changes i n t h e mass
ORML-DWG 71-7322
Primary
Se co nda ry
pump 14,255
2
Tertiary
m
17,370
BFon
n
QFn
lOOO'F ---+ I- Steam
0 I
I
lOOO'F
1200'F Primary HX
Secondary HX
R e heat er Q
Steam
13.3 x lo6 l b / h r A l l flow rates are f o r each of four loops
Fig. 1. Schematic Flowsheet of lOOO-MW( e ) MSBR Power Station as Modified with Addition of Third Loops to Trap 3H.
Feedwater
9 flow r a t e s of t h e s a l t s .
The flow q u a n t i t i e s shown on t h e flowsheet a r e
f o r each of t h e f o u r c i r c u l a t i n g loops. The secondary h e a t exchangers and t h e a s s o c i a t e d LiF-BeFa pumps can be arranged i n t h e r e a c t o r c e l l without changing t h e dimensions of t h e containment s t r u c t u r e , as i n d i c a t e d i n Fig. 2.
The l a y o u t provides
r e l a t i v e l y s h o r t p i p i n g between t h e primary and secondary h e a t exchangers t o keep t h e lithium-7 inventory low.
No major changes would be r e q u i r e d
i n t h e s a l t p i p i n g t o t h e steam g e n e r a t o r s and r e h e a t e r s .
On t h i s basis,
t h e c o s t e s t i m a t e s f o r t h e modified system do n o t i n c l u d e any expenses
for m o d i f i c a t i o n of t h e b u i l d i n g o r c e l l s t r u c t u r e .
3.
HEAT TRANSFER EQUIPMENT
The p h y s i c a l p r o p e r t i e s of i n t e r e s t f o r t h e f u e l and h e a t - t r a n s p o r t
salts are given i n Table 2.
(Sodium f l u o r o b o r a t e has been included f o r
comparison, although not used i n t h e modified MSBR system.) The c o s t s of t h e h e a t t r a n s f e r equipment were based on t h e estimated weights o f t h e v a r i o u s shapes of m a t e r i a l s used i n f a b r i c a t i o n , and on a u n i t p r i c e which r e f l e c t s t h e c o s t s of f a b r i c a t i o n , i n s p e c t i o n , t r a n s p o r t a t i o n , and i n s t a l l a t i o n ready f o r use.
The t o t a l i n s t a l l e d c o s t s of
H a s t e l l o y N and Incoloy 800, as used i n t h i s study, are l i s t e d i n Table
3.
A s i n t h e r e f e r e n c e design, t h e base p r i c e s of materials can be d e t e r -
mined w i t h r e l a t i v e l y good c e r t a i n t y , b u t t h e a d d i t i o n s t o provide t h e
total i n s t a l l e d cost g r e a t l y overshadow t h e b a s i c m a t e r i a l c o s t i n i m p o r t a n c e and a l s o involve considerable i n t u i t i v e j u d p e n t .
A s a rough check
on t h e reasonableness of t h e c o s t estimates, t h e c o s t s p e r square f o o t of h e a t t r a n s f e r s u r f a c e are compared i n Table 10.
1. Primary Heat Exchangers The c o s t e s t i m a t e f o r t h e primary h e a t exchangers i n t h e r e f e r e n c e design, a s r e p o r t e d i n
OWL-4541, has
been changed from
$7.3
million t o
$8.7 m i l l i o n t o r e f l e c t t h e r e v i s i o n s t o t h e design data, as i n d i c a t e d i n Table 4. The c o s t i n c r e a s e i s a l s o due t o adding i n t h e c o s t
about
of t h e baffles and t o i n c l u s i o n of t h e double-pipe c o o l a n t - s a l t nozzles, which had p r e v i o u s l y been assumed t o be covered by t h e p i p i n g c o s t
10
ORNL-DWG
71-7323
Fig. 2 . YSER Reactor Cell Layout I n d i c a t i n g Possible Location f a r Secordary Heat Exchanger and P u ~ p . (One of f o u r loops i s shown.)
Table 2. Selected P r o p e r t i e s of t h e MSBR Molten S a l t s Na,F-NaBF4
'LiF- BeF,
KN0,-NaN0,-NaNO,
Molecular weight, approximate
71.7-16-12-0.3 64
92-8 104
66-34 33
44.2-48.9-6.9& 84
Density, l b / f t 3 a t 1000째F
212
117
124
105
Viscosity, l b / f t - h r
41
29
7LiF-BeF,-ThF,-UF4 Composition, mole
4
a t 1000째F
S p e c i f i c heat, Btu/lb-"F
0.32
3 0.36
Thermal conductivity, Btu/f t -hr- " F
0.67 t o 0.68
0.23
0.58
3 0.37 0.33
Estimated cost, $/lb
57 * 00
0.50
12.00
0.15
13.3 x lo6 13,380
14.7 x lo6 17,370 288
b C i r c u l a t i o n required per loop for 5 5 6 - ~ w ( t )heat load: lb/hr gPm Liquidus temperature, "F
23.4 x lo6 14,260 930
a Eht e c t i c composit i on.
bBased on p r o p e r t i e s a t average temperatures i n MSBR system. C
Based on 250째F at i n modified MSBR.
0.57
850
12
Table
3.
Material Costs Used i n Estimates" Hastelloy N
Tubes, 3/8 i n . diam
Incoloy
$30/1b
1 / 2 i n . d i m and l a r g e r
20
17
S h e l l s and l i n e r s
10
7
Heads
15
12
Baffles
1-5
12
Rings
"20
18
Tube sheet s
20
18
Downcomers, l a r g e nozzles
15
12
Miscellaneous nozzles, e t c .
20
18
a
Includes c o s t of material, f a b r i c a t i o n , t r a n s p o r t a t i o n , inspection, and i n s t a l l a t i o n ready f o r use.
It was a l s o found t h a t t h e i n s i d e diameter of t h e s h e l l
allowance. stated i n
ORNL-4541 a p p l i e d t o
t h e i n n e r l i n e r r a t h e r than t o t h e
outer s h e l l . The design d a t a f o r t h e primary heat exchangers as modified t o use LiF-BeFa on t h e s h e l l s i d e are a l s o shown i n Table d a t a have not been r e c a l c u l a t e d u s i n g t h e May
4.
These design
1971 r e v i s i o n s t o t h e com-
p u t e r program (see I n t r o d u c t i o n ) , b u t t h e e f f e c t s of t h e changes could be estimated by u s i n g t h e i r influence on t h e r e f e r e n c e design primary h e a t exchanger c o s t s as a guide, as follows:
(+8.7$),heads (-1.4$), r i n g s (-l.O$), baffles (+4.1$). liner
tubes
(+6.4$), s h e l l
and
downcorners, U-bends and
The t u b e s and o t h e r p o r t i o n s of t h e primary h e a t exchanger i n cont a c t with t h e f u e l s a l t must be constructed of Hastelloy N.
This was
a l s o t r u e i n t h e r e f e r e n c e design f o r t h e p o r t i o n s i n contact with t h e sodium f l u o r o b o r a t e s a l t .
I n t h e modified design, however, consideration
W
Table 4. ~~
Primary Heat Exchangers ~
~~~
Revised Reference Modified YiBR Design MSBR With Third Loop
Coolant salt temperature, in-out, "F
5 56 1300-1050 850-1150
556 1300-1050 950-1200
Coolant salt
NaF-NaBF4
LiF-BeF,
Tube size (enhanced), OD x wall thickness, in.
3/8 x 0.035
3/8 x 0.035
Number of tubes
5803 24.4
6312 25.5 15,789 70.3 X 2.5 76.3 x 1/2 130
Capacity, MW(t),
each of four units
Fuel salt temperatures, in-out, "F
Length of tubes, ft Heat transfer area, fta Liner, ID x thickness, in. Shell, ID x thickness, in. Pressure drops: tube side, psi shell side, psi
13,916 67.6 x 2.5 73.6 x 1/2 130 116
118
Head thickness, in.
3/4
Number of baffles, disc and doughnut, 3/8 in. thick
21
3/ 4 34
Overall heat transfer coefficient, Btu/hr- fta- " F
785
672944
A.
Material costs with Hastellov N tubes and shell (in $1000): Tubes, at $30/lb
$ 2,457
2,823 666
$ 2,970 487 2,308 150 2,911 854
200
200
$ 8,660
$ 9,880
Shells, at $10/lb
414
Liners, at $10/lb
1,959
Heads, at $15/lb Rings and tube sheets, at $20/lb Downcomers, baffles, and doublepipe coolant nozzles, at $15/1b Installation allowance Total for four units
141
(continued)
Table
4
(continued) Revised Reference Design MSBR
Modified MSBR With Third Loop
B. b h t e r i a l c o s t s with H a s t e l l o y N t u b e s and Incoloy s h e l l ( i n $1000): Tubes, a t $30/lb S h e l l s , a t $8/lb Liners
, at
350 1J 658
$8/lb
Heads, a t $l5/lb
150
H a s t e l l o y N r i n g s and tubesheets, a t $20/lb Incoloy r i n g s , a t $17/1b Downcomer, a t $12/lb Double-pipe coolant nozzles
, at
$12/1b
1J
9O7 812 126 65
B a f f l e s , a t $12/lb
424
I n s t a l l a t i o n allowance
200
$ 8,661
Total
can be given t o use of l e s s expensive m a t e r i a l s i n t h e s h e l l s i d e of t h e system, provided t h a t no moisture i s p r e s e n t .
The more c o n s e r v a t i v e
approach i s t o use H a s t e l l o y N f o r a l l p o r t i o n s of t h e secondary system, and t h i s i s t h e b a s i s f o r t h e c o s t e s t i m a t e s shown i n P a r t A of Tables 1,
4, and 5.
Since t h e r e has been noteworthy success i n excluding water
from s a l t systems, however, it may be p r a c t i c a l t o use Incoloy, o r a
s i m i l a r material, i n t h e secondary system. case a r e shown i n P a r t B of Tables 1,
The estimated c o s t s i n t h i s
4, and 5.
It w i l l be noted t h a t
use of Incoloy would save about $3 m i l l i o n i n t o t a l c o s t s when i n d i r e c t charges a r e included. 2.
Secondary Heat Exchangers The secondary h e a t exchangers i n t h e modified MSBR p l a n t a r e en-
v i s i o n e d as U-shell and U-tube types, arranged v e r t i c a l l y i n t h e r e a c t o r c e l l , as i n d i c a t e d i n F i g . 2.
The design d a t a were generated on t h e
b a s i s of f o u r u n i t s with 3/8-in.-OD
tubing.
The arrangement was not
Table 5.
Secondary Heat &changers Modified MSBR With Third Loop
Capacity, each of f o u r u n i t s , M W ( t ) LiF-BeF,
( t u b e s ) temperatures, i n - o u t , "F
I(TJO,-NaNOa-NaNO,
( s h e l l ) temperatures, i m u t , "F
556 1200-950 750-1100
Tube s i z e ( n o t enhanced), OD x w a l l thickness, i n .
3/8 x 0.035
Number of t u b e s Length of t u b e s , f t
5989 44
Heat t r a n s f e r s u r f a c e , f t a
25,665
P r e s s u r e drops:
79.2
tube s i d e , p s i s h e l l side, p s i
Shell, I D x w a l l thickness, i n .
79.6 61.5 x 1/2
Head t h i c k n e s s , i n .
33 3 3/ 4
Overall h e a t t r a n s f e r c o e f f i c i e n t , Btu/hr-fta-"F
505
Number of b a f f l e s , crosscut, 3/8 i n . t h i c k Tubesheet t h i c k n e s s , i n .
A. Material c o s t with Hastelloy N t u b e s and Incoloy s h e l l ( i n $1000): Tubes, a t $30/lb Shell, a t @/lb Tubesheet, a t $20/lb Heads, a t $l5/lb B a f f l e s , a t $12/1b Nozzles, e t c . , a t $ 2 O / l b I n s t a l l a t i o n allowance Total f o r four u n i t s
$ 4,542 483 458 102 1,018 80 200
$m
B. M a t e r i a l c o s t w i t h Incoloy s h e l l and t u b e s ( i n $1000): Tubes, a t $27/lb S h e l l , a t $8/lb Tubesheets, a t $18/lb Heads, a t $12/lb Baffles, a t $12/lb Nozzles, e t c . , a t $18/1b I n s t a l l a t i o n allowance Total f o r four u n i t s
$ 3,670 483 370
78 1,018
65 200
$5,879
16 optimized, however, and although s u f f i c i e n t f o r c o s t - e s t i m a t i n g purposes, I
t h e r e a r e i n d i c a t i o n s t h a t f u r t h e r study may be needed.
For example,
t h e c a l c u l a t e d s h e l l diameter of over 60 i n . i s questionable f o r t h e UThe t u b e s i z e needs optimizing i n t h a t t h e 3/8-in.-
s h e l l configuration.
OD t u b i n g i s needed t o minimize t h e LiF-&Fa
inventory and s u r f a c e r e -
quirements, but it i s r e l a t i v e l y expensive compared t o l a r g e r s i z e s ( s e e Table
3).
Consideration could be given t o u s e of e i g h t u n i t s r a t h e r t h a c
f o u r , and t o use of s t r a i g h t - t u b e designs, although space i n t h e c e l l i s somewhat l i m i t e d . A s p r e v i o u s l y discussed, t h e r e i s a p o s s i b l e o p t i o n i n s e l e c t i n g m a t e r i a l s t o be used on c o n t a c t with t h e LiF-&Fa
salt.
P a r t A of Table
5 shows t h e estimated d i r e c t c o s t of t h e secondary h e a t exchangers
if
c o n s t r u c t e d w i t h H a s t e l l o y N t u b e s and heads, and P a r t B i n d i c a t e s t h e c o s t i f Incoloy i s used f o r t h e s e p a r t s .
3.
Steam Generators The c o s t estimate f o r t h e steam g e n e r a t o r s i n t h e r e f e r e n c e design
was changed from $6.3 m i l l i o n t o $7.2 m i l l i o n t o r e f l e c t t h e r e v i s i o n s i n t h e design d a t a .
The p r i n c i p a l d i f f e r e n c e s were due t o an i n c r e a s e
i n t h e number and l e n g t h of t h e t u b e s and an i n c r e a s e i n t h e t h i c k n e s s of t h e t u b e s h e e t s used i n t h e c o s t e s t i m a t e . shown i n Table
The d a t a and e o s t s a r e
6.
The design d a t a and t h e e s t i m a t e d c o s t of t h e steam g e n e r a t o r s f o r t h e modified MSBR system using KNO,-NaNOa-NaNO, a l s o shown i n Table
6.
on t h e s h e l l s i d e a r e
The lower t o t a l c o s t of t h e u n i t s for t h e modi-
f i e d design i s p r i m a r i l y due t o use of Incoloy r a t h e r than H a s t e l l o y N.
It may be noted t h a t t h e steam g e n e r a t o r s a r e designed f o r 555째F e n t e r i n g feedwater r a t h e r than t h e 551째F temperature c a l l e d f o r i n t h e flowsheets.
A t e c h n i c a l i t y i n t h e computer program made it necessary t o
r e v i s e t h e number, b u t s i n c e t h e t o t a l amount of h e a t t o be t r a n s f e r r e d
was not a l t e r e d , t h e only s a c r i f i c e t o accuracy was r e l a t i v e l y small velocity effects.
17 Table
6.
Steam Generators Revised Reference Design MSBR
For each of
Modified MSBR With Third Loop
16 u n i t s :
Capacity, MW( t )
121
121
me
U-shell, U-tube
U-shell, U-tube
Major m a t e r i a l of c o n s t r u c t i o n
Hastelloy N
Incoloy
Heat t r a n s p o r t s a l t ( s h e l l s i d e )
NaJ?-NaBF4
KNO, -NaNOa -NaNO,
S a l t temperatures, i n - o u t , "F
1100-750
Feedwater temperature, "F
1150-850 700
Steam temperature out, "F
1000
1000
Steam p r e s s u r e , p s i a
3625 1/2 x 0.077 393 76 3929 18.3 x 3/8 18
3625
Tube s i z e , OD x wall t h i c k n e s s , i n .
Number of t u b e s Tube l e n g t h , f t Heat t r a n s f e r s u r f a c e , f t a Shell, I D x w a l l thickness, i n . Number of baffles
(3/8 i n . t h i c k )
Head ( s p h e r i c a l ) t h i c k n e s s , i n .
4
P r e s s u r e drops:
152
tube side, p s i
shell ( s a l t )
61
555
1/2 x
Tubes:
Cost, $/lb T o t a l c o s t ($1000)
Shells:
Cost, $/lb T o t a l c o s t ($1000)
Heads:
Cost, $/lb T o t a l c o s t ($1000)
Tubesheets: Cost, $/lb T o t a l c o s t ($1000) Misc.:
Cost, $/lb T o t a l c o s t ($1000)
I n s t a l l a t i o n allowance T o t a l c o s t ($1000)
0.077
341 99 4428 17 x 3/8 28 4 125 90
side, p s i
Overall U, Btu/hr-fta-"F Material c o s t s (all 16 units):
800
655
18
4.
Steam Reheaters The estimated c o s t of t h e steam h e a t e r s i n t h e r e f e r e n c e design
was r e v i s e d from
$1.7 m i l l i o n
t o $1.6 m i l l i o n t o correspond t o t h e re-
v i s e d design d a t a , as shown i n Table
7.
Although t h e r e v i s e d u n i t has
more s u r f a c e , t h e p r e v i o u s l y used p r i c e of H a s t e l l o y N t u b i n g d i d not r e f l e c t t h e lower u n i t p r i c e of 3/4-in.-OD
t u b i n g as compared t o 3/8-
i n . -OD t u b i n g . The design d a t a and estimated c o s t of t h e modified r e h e a t e r s using on t h e s h e l l s i d e a r e a l s o shown i n Table 7.
XNO3-NaN0,-NaNO3
Using
Incoloy r a t h e r t h a n H a s t e l l o y N accounted f o r t h e r e d u c t i o n i n c o s t t o $1.2 m i l l i o n .
It w i l l be noted t h a t t h e u n i t i s designed f o r 550째F
e n t e r i n g cold r e h e a t temperature, as taken d i r e c t l y from t h e high-pressure t u r b i n e exhaust.
5. Reheat Steam P r e h e a t e r s Reheat steam p r e h e a t e r s were used i n t h e r e f e r e n c e design t o h e a t t h e high-pressure t u r b i n e exhaust from
550째F t o 650"~ b e f o r e t h e stem
e n t e r e d t h e r e h e a t e r s t o avoid p o s s i b l e problems of c o o l a n t - s a l t f r e e z i n g . The c o s t of t h e p r e h e a t e r s was underestimated i n t h e r e f e r e n c e design r e p o r t because t h e t h i c k n e s s of t h e s p h e r i c a l heads was used i n t h e c a l c u l a t i o n s as 1/2-in. r a t h e r t h a n t h e c o r r e c t value of 2-1/2 i n .
Further,
t h e m a t e r i a l c o s t s assumed f o r t h e Croloy i n t h e r e f e r e n c e design appeared t o o low.
The r e v i s e d c o s t e s t i m a t e f o r t h e p r e h e a t e r s i s now $924,000,
as shown i n Table 8. The p r e h e a t e r design was n o t optimized.
Use of 3/8-in.
t u b e s may
involve a c o s t p e n a l t y , and some improvement i n c o s t s might be obtained i f t h e number of u n i t s was i n c r e a s e d .
The modified MSBR with t h e t h i r d loops added t o t r a p tritium does
not r e q u i r e use of p r e h e a t e r s because of t h e low l i q u i d u s temperature of the nitrate-nitrite salt.
6. General E f f e c t s of Revising and Modifying t h e Heat T r a n s f e r Equipment The t o t a l c o s t e f f e c t s of r e v i s i n g t h e d e s i g n d a t a f o r t h e h e a t t r a n s f e r equipment i n t h e r e f e r e n c e design a r e summarized i n Table The n e t i n c r e a s e of about
$4 m i l l i o n ( i n c l u d i n g i n d i r e c t c h a r g e s )
9.
Table
W
7. Steam Reheaters Revised Reference Modified MSBR Design MSBR With Third Loop
For each of 8 units: Capacity, MW( t )
36.6
36.6
Major material of construction
Hastelloy N
Incoloy 800
Heat transport salt
NaF-NaBF4
KNO, -NaNOa-NaN03
Salt temperatures, in-out, OF
1150-850
1100-750
Steam temperature in,
650
550
Steam temperature out, "F
1000
1000
Entrance steam pressure, psia
580 3/4 % 0.035 696 28
Heat transfer surface, fta
580 3/4 x 0.035 400 30 2376
Shell, ID x wall thickness, in.
21.2 x 0.5
21 x 0.5
Number of disc and doughnut baffles
21 & 21
30
Head thickness, in.
0.5
0.5 40 90
O F
Tube size, OD x wall thickness, in. Number of tubes Tube length
Pressure drops:
tube side, psi shell side, psi
Overall U, Btu/hr-fta-"F
30
60 306
2520
29
340
Material costs (all 8 units):
$/ lb
Tubes:
cost, in $1000
$/lb
Shells :
cost, in $1000 Tubesheets :
$/lb cost, in $1000
Heads :
$/lb cost, in $1000
Eaffles:
$/lb cost, in $1000
Nozzles, etc: $/lb cost, in $1000
I n s t a l l a t ion allowance W
Total cost, in $1000
200
$ 1,216
Table
8.
Reheat Steam P r e h e a t e r s Revised Reference Design MSBR
For each of
8 units: 12.3
Capacity, MW( t ) Major m a t e r i a l of eo
tructi
Croloy
S h e l l - s i d e conditions:
551 595
Heated steam entrance temperature, "F Entrance p r e s s u r e , p s i a
:
Tube-side conditions: Heating steam e n t r a n c e temperature, "F
1000
Entrance p r e s s u r e , p s i a
3600 318 x 0.065 603
Tube s i z e , OD
x w a l l thickness, i n .
Number of t u b e s
13.2 781
Tube l e n g t h , f t Heat t r a n s f e r s u r f a c e , f t a O v e r a l l U, Btu/hr-fta-"F
20-114 x 7/16 162
Head t h i c k n e s s , i n .
242
Shell, I D x w a l l thickness, i n .
M a t e r i a l c o s t s ( a l l 8 u n i t s ) , i n $1000: Tubes, a t $18/1b S h e l l s , a t $8/lb Heads, a t $10/lb Tubesheets, a t
$18/lb
$
252
88 296 323
Nozzles, e t c . , a t $18/1b
72
I n s t a l l a t i o n allowance
25
21 Table
V
9.
Revised Reference Design Costs f o r Heat Transfer Equipment ( i n $1000) Reference MSBR De signa
Revised Reference Design Costsb
$ 7,347
$ 8,660
Steam g e n e r a t o r s
6;270
7,230
Reheater s
1,668
1,565
135
924
Primary h e a t exchangers
Reheat steam p r e h e a t e r s
$ 15,420 $ 18,379 I n c r e a s e i n r e f e r e n c e design d i r e c t c o s t s $ 2,959 $ ’ 3,935 I n c r e a s e i n t o t a l c o s t , including i n d i r e c t s i
Reference design t o t a l c o s t
a
202,654
T o t a l r e v i s e d r e f e r e n c e design c o s t
a As l i s t e d i n
$ 206,589
ORNL-4541.
bFor H a s t e l l o y N f u e l and c o o l a n t - s a l t systems.
r e s u l t s i n r a i s i n g t h e t o t a l e s t i m a t e d p l a n t c o s t of t h e r e f e r e n c e design
MSBR p l a n t from about $202 m i l l i o n t o $206 m i l l i o n . Use of Incoloy r a t h e r t h a n Hastelloy N f o r t h e p o r t i o n s of t h e seconda r y system i n contact with LiF-BeF,
would save about $1.6 m i l l i o n i n t h e
t o t a l c o s t ( i n c l u d i n g i n d i r e c t charges) of t h e primary heat exchangers, about $1.3 m i l l i o n f o r t h e secondary h e a t exchangers, and about $200,000 f o r t h e secondary s a l t piping, f o r a t o t a l savings of about $3 m i l l i o n . The c o s t s of t h e h e a t t r a n s f e r equipment on a square f o o t basis are compared i n Table 10.
While t h e v a l u e s are not p a r t i c u l a r l y conclusive,
t h e y i n d i c a t e t h a t t h e estimated c o s t s a r e g e n e r a l l y w i t h i n reason f o r t h i s type of n u c l e a r power s t a t i o n equipment.
4.
SALT-CIRCULATING PUMPS
Since s a l t - c i r c u l a t i n g pumps of t h e s i z e r e q u i r e d f o r t h e 1000-MW(e)
MSBR s t a t i o n have never been f a b r i c a t e d , t h e cost-estimating method used W
22 Table 10.
Estimated Direct Cost of I n s t a l l e d Heat Transfer Equipment p e r Square Foot of Surface Revised Reference Design MSBR
Modified MSBR With Third Loop
Primary h e a t exchangers Hastelloy N t u b e s and s h e l l Hastelloy N t u b e s and Incoloy s h e l l
$ 155
-
$ 147 129
Secondary h e a t exchangers Hastelloy N tubes and s h e l l
115
67 43 76
82
54
149
none
Hastelloy N t u b e s and Incoloy s h e l l Steam g e n e r a t o r s Steam r e h e a t e r s Reheat steam p r e h e a t e r s
i n t h i s study and i n t h e r e f e r e n c e design r e p o r t i s based on published c o s t s of similar pumps (as a d j u s t e d f o r c a p a c i t y and head requirements), on MSRF, pump c o s t experience, and on t h e b a s i s of considerable i n t u i t i v e judgment.
Table 11 i n d i c a t e s t h e pumping requirements which served as
a b a s i s f o r a s s m i n g allowances f o r t h e pump c o s t s i n t h e modified WEB
plant. U s e of t h e t h i r d c i r c u l a t i n g s a l t system would add f o u r pumps of
about 2700 hp each, would reduce t h e power requirements of another s e t of f o u r pumps from 3200 hp t o 1800 hp each, and would e l i m i n a t e t h e need f o r t h e two 6000-hp each pressure-booster pumps i n t h e feedwater system.
A s shown i n Table 12, t h e connected load of t h e pump motors i s
reduced by a t o t a l of about
5,400 kW(e) i n t h e modified system.
If it
i s assumed t h a t a l l t h e pumping energy i s u s e f u l l y converted t o h e a t , about 5,400 kW(t) i s t h u s not a v a i l a b l e i n t h e modified system f o r conv e r s i o n i n t o e l e c t r i c pow=
a t t h e average o v e r a l l p l a n t e f f i c i e n c y of
44.4%. The n e t savings i n a u x i l i a r y e l e c t r i c l o a d i s t h u s about 3,000 kW(e). With power worth 5.3 mills/kWhr, and 80% p l a n t f a c t o r , t h i s amounts t o about $111,00O/year. A t 13.7% f i x e d charges, t h e savings i s equivalent t o a p l a n t investment of about $817,000. been taken i n P a r t s A and B of Table 1.
C r e d i t f o r t h i s has
23 Table 11. Estimated Design Data and Allowances f o r I n s t a l l e d Costs of S a l t - C i r c u l a t i n g Pumps
W
__
~
Modified MSBR SecondaryS a l t Pump Ref. MSBR
Fuel-Salt Pumps For each of
SecondaryS a l t mUnp
TertiaryS a l t Pump
4 pumps:
Actual c a p a c i t y , gpm Nominal c a p a c i t y , gpm Average s a l t d e n s i t y , l b / f t a Estimated t o t a l head, f t a Estimated horsepower Cost allowance, i n $1000, f o r t o t a l of 4 pumps
14,255
18,768
13,380
17,372
16,000
20,000
16,000
20 000
208 1.50 2360
117
124
300 3210
230
105 300
$3300
$4400
1800 $2750
2680 $3800
,
-
a
Estimate based on c a l c u l a t e d
&Is
i n h e a t t r a n s f e r equipment.
bCost assumed t o be i n p r o p o r t i o n t o c a p a c i t y and horsepower r e q u i r e ment. Table 12. Estimated Pumping Power Requirements and Worth of Improved B f i c i e n c y of Modified MSBR Cycle Reference Design MSRR T o t a l pumping power, kW( e ) : Pressure-booster pumps Fuel-salt pwps Secondary-salt pumps Tertiary-salt pumps
none
9,200 7,039 9,575
*
Savings i n pump power w i t h modified system, kW( e ) Difference i n h e a t i n p u t s t o systems from pump work, kW(t) E l e c t r i c power p o t e n t i a l of 5,400 kW(t) a t 44.4% thermal e f f i c i e n c y , kW(e) N e t savings i n power with modified cycle, kW( e ) C a p i t a l c o s t worth of 3,000 kW(e) a t 80% p l a n t f a c t o r , 13.7% f i x e d charges, and power worth 5.3 mills/kWhr
Modified MSBR With Third Loops
7,039 5,369 5,400
5,400 2,400 3,000
$817,000
24 5.
SALT INVENTORY COSTS
The modified primary h e a t exchangers w i l l contain about 56 f t 3 more f u e l s a l t t h a n t h o s e used i n t h e r e f e r e n c e design, as i n d i c a t e d i n Table
13. On t h e basis of t h e $57/1b f u e l - s a l t c o s t used i n ORNL-4541,
t h i s amounts t o an a d d i t i o n a l investment of @7l,OOO
f o r t h e MSBR p l a n t .
Following t h e procedures used i n t h e r e f e r e n c e r e p o r t , however, t h i s c a p i t a l c o s t i s not included i n t h e p l a n t c a p i t a l c o s t b u t i n t h e f u e l cycle c o s t .
This would i n c r e a s e t h e f u e l - c y c l e c o s t by about 0.013
mills/kWhr.
( I n both t h e r e f e r e n c e and t h e modified p l a n t designs it
was assumed t h a t t h e cleanup c o s t s f o r t h e f u e l s a l t a t t h e end of t h e 30-year p l a n t l i f e would be g r e a t enough t o make it have e s s e n t i a l l y no I*
resale, o r "scrap" value. )
The estimated p r i c e of t h e n i t r a t e - n i t r i t e salt used i n t h e modified design i s 15 c e n t s / l b as compared t o 50 c e n t s / l b f o r t h e sodium fluorob o r a t e used i n t h e reference design.
Both of t h e s e s a l t s are assumed t o
have no resale value a t end of t h e u s e f u l l i f e of t h e p l a n t . A s shown i n Table
14, t h e
estimated volume of t h e LiF-EeF,
t h e secondary system i s about 3200 f t 3 .
Almost t h r e e - f o u r t h s of t h i s i s
i n t h e s h e l l - s i d e of t h e primary h e a t exchangers.
Using t h e same p r i c e s
as i n ORNL-4541, where 7 L i i s assumed t o c o s t $120/kg, t o c o s t $16.50 and $7.50/lb, i s about $12/1b.
used i n
and 7LiF and &Fa
r e s p e c t i v e l y , t h e estimated c o s t of 7LiF-BeFa
The t o t a l estimated c o s t of t h e secondary s a l t inventory
i s about $4,800,000,
as shown i n Table
13.
It i s assumed t h a t t h e s a l t
w i l l l a s t t h e l i f e t i m e of t h e p l a n t without reprocessing o r replacement
costs.
A t t h e end of 30 years it i s assumed t h a t t h e s a l t w i l l have a
resale value of SO'$, o r @ / l b .
(The s a l t could be used as t h e secondary
coolant i n another MSBR o r as t h e c a r r i e r t o make up new batches of f u e l
salt.)
The p r e s e n t worth of $2,400,000 t h i r t y y e a r s hence a t 8% i n t e r e s t
i s $239,000, and c r e d i t f o r t h i s h a s been taken i n Table 1.
25 Table
13. Estimated S a l t Inventory Costs Reference Design MSBR
Modified MSBR With Third Loops
___-
Total volume,
7LiF-BeF, -ThF, -UF4
7LiF-BeF,-ThF4-UF,
Fuel salt a
ft'
Total weight, l b b Total c o s t Resale value a f t e r 30 y r
2200
2256
457,000
469,000
$23,533,000
$24,204,000
0
0
NaF-NaBF,
7LiF-BeF2
Total volume, f t 3
8400
3200'
Total weight, l b
1,000,000
397,000
Average cost, $/lb
$0.50
$12d
Total c o s t
$500,000
$4,800,
Resale value a f t e r 30 yr
0
$2,400,000
Secondary s a l t
Present worth, a t 8%
$239,000 KNO,-NaNO, -NaNO,
Tertiary salt
8bOe
Total volume, f t 3 Total weight, lb
ooo
none
~0,000
Average cost, $/lb
$0.15
Total cost
$135,000
Resale value a f t e r 30 y r
0
a
Includes 480 f t 3 i n chemical processing p l a n t .
bEased on f e r t i l e s a l t cost of about $57/lb and an average inventory value of $31/lb i n t h e chemical p l a n t . C
See Table 11.
dEased on 7 L i a t $l20/kg,
7LiF a t $16.50/lb,
&Fa a t $7.50/lb.
e Assumed t o have same volume as reference design secondary system.
26
Table
14.
Estimated Volume of LiF-BeF, S a l t i n Secondary System of Modified MSBR
Primary h e a t exchanger volumes Shell, f t 3 per u n i t
+
Head, f t 3 p e r u n i t
+ 13
Tubes, f t 3 p e r u n i t
- 123
Liner, f t a p e r u n i t
-
Downcomer Baffles
90" o u t l e t bends
95 - 5 - 17 + 19
N e t volume one u n i t
T o t a l volume
762 f t 3
554 f t 3
4 units
2,216 f t 3
Secondary h e a t exchanger volumes ( t u b e s i d e ) Tubes Head allowance Volume i n one u n i t T o t a l volume i n
4- u n i t s
612
Secondary s a l t p i p i n g volumes Volume of 35-ft 20-in. pipe per u n i t , f o r t o t a l 4 u n i t s Drain tank h e e l allowance T o t a l estimated volume of s a l t
306
66 3,200 f t 3
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