ORNL-TM-0269.txt

OAK RIDGE NATIONAL LABORATORY'LBHAR( ¥

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LEGAL NOTICE

This report wox prepufed as ah sccount of Gavnrnmm sponsorad work. Nmfhnr the United S#arps

nor the Commission, nor any persen acting ori bnhfllf of the Commission:

A, Makes ony wnrrf.;m'y or representation, expmssed ot implied, with respect to the a«:cmuqr,
compietensss, or usefulness of the information contained in shix report, ar that the use of
any infarmation, apporotus, . method, or precess disclosed in !h: report. may ot infringe
privately ownsd rights; or

B. Astumes any liahilities with respect to the use of, or for damuges resuviting from the use of
ony infoemation, appnraws, method, or process disclosed in this repore,

As uysed in the shove, “person scting on behalf of the Commqssmu includes aay cmp!ogea ar

contractor of the Comm«ssuan, ~ smployes of such confractor, to the sxtent thut such empkn,—na

or tontractor of the Commission, or employee of such contracyer prepyres, disseminates, or

provides dccess to, any informatian pursuum 1 Pus amployment ot controct with the Cammnssron,'

or his employment wnfh such contrector.

 

 
C1-

5}6 th Natural Ccnvectlen

5.Introductlon

Studies have been madeil 2)

of 5 Mw and 60 M thermal output. The folléwing study of .a 576 natural
cgnvection reactor was made to campare w1th the famlly of‘large mmlten salt

of mmlten salt natural convectlan.reactors

| reactors heing presently studled o . .
The . chzef purpose af this study ig tm determzne the approximate size
of the companents &fid fuel volume mf the fuel circuit of a 576 M natural

'_convection m@lten salt reactor

JRlb&T Calculatlans

For the purpoae of this study a rather simyle conflgnratlon of . reactar,
heat ewchanger, and plplng was chosen as shown in. Flg. I. . All calculatxens
were done on the baszs of one heat exchanger and one set of rlsers and &awnu,
-cmmers. ance the frictzonal losses in tha pmplng are determined prlmarlly
| the 5 ngle r;ser can.be replacefl by a: number of rlsers hav1ng the same height

'and total crass sectzona. leewlse, the heat exchanger can be replaaed by a

tubes .
The - fmllawmng expression was derlved fOr the helght cf the riser (see
 Append1x A).

 

 

 

o s
APAtED5+8hD....g’: é"+81f 22
o BP C {c. _ gfifi C
B o= e o &
"B F
5
aAt3D ~16f 2 =

| gpxc

L LABORATORY LIBRARIES

i mxmm\\mum\\\mmm +

3 4u5k DE4B7UE 1

 

 

 

 
 

Riser Calcuylations (continued)

1

Where: H = height of riser - £t {see Fig. I)

Ar
A
D

h

pressure drop in heat exchanger - 1b/£t2

-

i

temperature drop in heat exéhanger %p.

dlameter of rlser - ft.

B

H

1 loss due to el's, exlt:anfl ent of reactcr, exlt and eni of heat

exchanger-~ 1.6 velocity heads.

power auiputku‘SkszGGO Btu/qgc

.aécel of‘gravity - Bé'ayft/éece

= spec&flc heat - O. 52 Bt/ lb

20 ft (see Flg 1)

frlctlon factor = .02 : ,
temperature coefficient of den51ty - 0. 0121 lb/ft Op
degsity of fuel = 123 lb/ft :

B

1

B8 oH

i

T Ok om0
o 2 - g ‘

Fér an eight foot diameter resctor the”vdlgme of the piping will be

VP‘%%DE (2 H + 2@ -.8)

for each value of‘[&P and th this volume will be a m;nimum at aame,value of
D and H. .
; Fig 13 is a plot of piping volume versus rlser helght for Zkt 200° and
values mf ZXQ of 10, 20, §O, hO, and 50 lb/ft Slmllar plots were made - for
At;*-l?fi , 225 s aad 250 - The mxnimum\values of plplng volume and the )
-assoc1ated riser heights and dlamsters are plctted agalnst heat exchangex pres~f
sure drmp in Flgs 11X and IV | ' '

Heat Exchangef‘Calculations:

On the basis that the heat exchanger 15 ‘of the counterflow tube and shell
deslgn with the fuel in the tubes and that the. Nusselt number Gver the range
Heat Exchanger Calculations (continugd

investlgated is canst&nt and equal to h(3), we derlve the follnwing relation-
shlps (gee Appendlx B) | | | |

 

Ly - 286.5 @
kAt |
a | ‘
? 1/2
| JQE.+ 12K\ ™
N = ’ — . .
e Ata® gPEA P
b ‘

The volume of the heat exchanger 1s:

Ti"ZHE”'&: vfubes + VHeafler

i TR a) 3§
B 2:

Where:
| L = 1ength of tube - ft

N = number of tubes

K= thermal ccnfluctlvity of fUfil 3 5 Btu/hr - ft - p
At = temperature drop in heat exchanger p
t& = average temperature d;fferential. OF‘
@ = tube jnside dia. - .05 ft. (fl 8062 )
I = viscosity of fuel = 0.17h & 0

G = heat output. Btu/sec

1b/hr - ft

C = specific-heat of fuel. Btu/lb " OF_
= density of fuel = 123 lb/ft

From.thls we can calculate L N, and heat exchanger volumfi against ‘heat
exchanger pressure drep for dlfferent Z\t s. The temperatures used were:
fuel entering the heat exchanger at 1210 E and leaving at 960°F to 1055°F;
The wall temperature was taken as golng from 850 to 1050 , glving the
following tem@erature conditions:
ol

Heat-Exchanger_Galculatigns (continued)

 

Fuel Exifi ,. At - At | 1 fitz
Tfimperétfire - |
1035 175 | 172.5 1.01k
1010 200 | 160.0 | 1.250
985 o5 ; 47,5 | 1.595
960 250 135.0 1.852

The: tot&l vclume of the system is equal to the valume of tha piping plus

3

the volume: of the heat exchanger plus BOQ £t~ for the reactar anfi.expansian

tanx. Flg V- platfi riser dlameter, heat excflanger tube 1ength and number

. of tubes, an& total VOlume of the syatem.agalnst riser height

Biscusaion

On the basis of this prellmlnary 1nvest1gation, 1arge natural convec-
tlmn reactors 4o not seem to be vEry attractlve._ The elmmination‘af fue&
pumps seems to be more than balanced by the increase in.fuel‘valume, and

number of haat exchanger tubes alfihdugh it is possible that the 1arge fiumher

of heat exehanger tubes can be reduced by using fuel outside of fiwned tubes.

b}

the cost of a natural convection reaétcr to be higher than com@arable forced

An investigatlan into the cost of various molten salt reactcr tyPE$( shows

fual c1rculati0n 5ystems.
-Heférefigas
- 1 'Rt}mie , F. B. and K;Lnycm, B W., "A Mmlten Salt Natural Cnnvectmn
- .Reactar System", ORNL-CF 58-2 hé

'Ei;_zasler, s Experzmental 5 Mw Thermal Convectlon Mnlten Salt Reactor”,
- OREL-CF 58 5-66 -

5 P&cfidams, W’ H., "Heat T‘ransmissmn 5 McGraw-Hill Bcak Co y Inc s 5rd
- Ed. (195u), ppn 229 239,

b, Whltmam, G. D. Mclten Salt Reactcr Ccst Stucly", ORNL CF 58 8-50

o
 

 Appendix A
Hystrostatic head for flow = S—r=
-Frigtion loss i piping =1 &= +h ~—+h

Where: | 1' = 2H + 1

 

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VOLUME OF PIPING

V-PIPING -
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Distribution

1-3, DTIE, AEC
L, M. J. Skinner