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k .. LAMS-3067

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I

LOS ALAMOS SCIENTIFIC LABORATORY

OF THE UNIVERSITYOF CALIFORNIAo LOSALAMOS NEW MEXICO

F.

. ..-

‘; ,

LOS ALAMOS CRITICAL-MASS DATA

{. “.

I

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b #

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am F~-— ——

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ClC-l4 REPORT COLLECTION

$% _:_ - -

~m - -,:

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~m . REPRODUCTION ..-.

COPY

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.

.

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LEGAL NOTICE

4,

\

This report was prepared as an account of Government sponsored work, Neither the United States, nor the

Commission, nor any person acting on behalf of the Commission:

A. Makes any warranty or representation, expressed

or implied, with respect to the accuracy, completeness, or

usefulness of the information contained in this report, or

that the use of any information, apparatus, method, or process disclosed in this report may not infringe privately

owned rights; or

B. Assumes any liabilities with respect to the use

of, or for damages resulting from the use of any information, apparatus, method, or process disclosed in this report.

As used in the above, “person acting on behalf of the

Commission” includes any employee or contractor of the

Commission, or employee of such contractor, to the extent

that such employee or contractor of the Commission, or

employee of such contractor prepares, disseminates, or

provides access to, any information pursuant to his employment or contract with the Commission, or his employment with such contractor.

Printed in USA. Price $1.50. Available from the

office of Technical Services

U. S. Department of Commerce

Washington 25, D. C.
LAMS-3067

UC-46, CRITICALITY STUDIES

TID-4500 (28th Ed.)

.

LOS ALAMOS SCIENTIFIC LABORATORY

OF THE UNIVERSITY OF CALIFORNIA LOS ALAMOS NEW MEXICO

REPORT WRITTEN. April 1964

REPORT DISTRIBUTED: May 6, 1964

LOS ALAMOS CRITICAL-MASS DATA

by

H. C. Paxton

Contract W-7405-E NG. 36 with the U. S. Atomic Energy Commission

All LA?& reporte are informal doeumente, usually prepared fora speoialpurpeee and primarily prepared for uee withinthe Leboretory retherthen for

geneml dietrlbutfon.l’hierepertbee not been edited,rwdewed, or verified

for eooureoy. AU LAM9 reperteexpress the vlewe of the authors 8.9 of the

time they wexw wrlttm auf do nti Mcemm.rfly reflecttheepinioneof the Los

Alamos SolentIffo L8beratory or the final npinion of the euthors on the eubjeot.

1
sb

.

.U

u

.“
ABSTRACI’

Tabulated are critical masses of simple systems, which

have been measured at Los Alamos through the year 1963.

.

“-

3
..

.

4

.“
u.,

,.

TABLE OF ~NTENTS

Page

ABSTRACT . . . . . . . . . . . . . . . . . . . . . . . 3

INTRODUCTION . . . . . . . . . . . . . . . . . . . . . 9

IA1

IA2

IA3

IB1

IB2

IB3

ICl

IC2

IC3

IC4a

TABLES

Highly Enriched U Metal, Unreflected . . . . . . 11

U(93.4) - U(N) Metal Cylinders,

Unreflected . . . . . . . . . . . . . . . . . .12

U(93.3) - U(N) Metal Cylinders,

15.00” Diameter, Unreflected . . . . . . . . . . 13

Enriched U Metal Sphere or Pseudosphere,

U(N) Reflector. . . . . . . . . . . . . . . . .14

Enriched U Metal Cylinder, Pseudocylinder

or Parallelepi.ped, U(N) Reflector . . . . . . . 15

Miscellaneous Enriched U Metal,

U(N) Reflector. . . . . . . . . . . . . . . . .16

Highly Enriched U Metal, Reflector of

Th, W, WC, MoorMo2C . . . . . . . . . . . . .17

Highly Enriched U Metal, Reflector of

Zn, Cu, Ni, Co,orFe . . . . . . . . . . . . .18

Highly Enriched U Metal, Reflector of

Ti, Al, A1203, Mg, Be, or BeO . . . . . . . . . 19

Highly Enriched U Metal, Complete

Graphite Reflector.. . . . . . . . . . . . . .2o
TABLES (Continued)

Page

Highly Enriched U Metal, Partial

Graphite Reflector.. . . . . . . . . . . . . .21

IC4b

IC5 Highly Enriched U Metal, Reflector of

D20 (99.8%) . . . . . . . . . . . . . . . ...22

Highly Enriched U Metal, Complete

Reflector of H20 or Polyethylene . . . . . . . . 23

IC6a

IC6b Highly Enriched U Metal, Complete

Reflector of Paraffin . . . . . . . . . . . . . 24

IC6C Highly Enriched U Metal, Partial Reflector

‘f ‘2°’ Polyethylene, Lucite, or Paraffin . . . 25

..

IC7

IIA1

Highly Enriched U, Mixed Reflector . . . . . . . 26

U(93.3) Metal Cylinders Diluted with

Fe, Ni, cu. or Zn, 15” Diameter, Unreflected . . 27 I

U(93.3) Metal Cylinders Diluted with

Mo, Ta, or W, 15” Diameter, Unreflected . . . . 28

IIA2

IIA3 U(93.3) Metal Cylinders Diluted with 

Al, Zr, or Hf, 15” Diameter, Unreflected . . . . 29 

IIB1 U(93.3) - Graphite Cylinders, Unreflected . . . 30

IIB2a Graphite-Moderated Highly-Enriched U,

Reflector of Graphite . . . . . . . . . . . . . 31

IIB2b Graphite-Moderated Highly-Enriched U,

Reflector of Be (Plus some Graphite) . . . . . . 32

IIC1 Lucite Moderated U(93.16), Unreflected . . . . . 33

IIC2a Lucite Moderated U(93.16), > 6“ Thick

Lucite Reflector . . . . . ~ . . . . . . . . . . 34

IIC2b Lucite Moderated U(93.16) Slabs, 6“ Thick

Lucite Reflectors on Two Large Surfaces Only . . 35

Lucite-Graphite Moderated U(93.16),

Unreflected . . . . . . . . . . . . . . . . . . 36

IID1
-’.

./

IID2a

IID2b

IIE1

IIE2

IIFla

IIFlb

IIF2

IIF3

IIIA1

IIIA2

IIIB1

IIIB2

IIIB3

IIIB4

IIIB5

IIIB6

TABLES (Continued)

Page

Lucite-Graphite Moderated U(93.16),

Lucite Reflected . . . . . . . . . . . . . . . 37

Lucite-Graphite Moderated U(93.16) Slabs,

6“ Thick Lucite Reflectors on Two

Large Surfaces Only . . . . . . . . . . . . . . 38

Diffuse U(93.1) Reflected by Thick D20

or Be (Cavity Assemblies) . . . . . . . . . . . 39

U(93.65)0 F -D O Solutions, Bare,D20 or

Graphite ?e?le?ted . . . . . . . . . . . . . . AO

U(14.67)02S04-H20 Solution, Sphere . . . . . . 41

U(93.5)-Phosphate Aqueous Solution,

Cylinders, 3.o” Thick Fe Reflector . . . . . . 42

Enriched-Uranium Hydride Composition . . . . . 43

Lattices of U(94) Metal Units, H20

Moderated, H20 Reflected . . . . . . . . . . . 44

Plutonium-Metal Spheres . . . . . . . . . . . . 45

Plutonium-Metal Cylinders . . . . . . . . . . . 46

Diluted Pu Cylinders, 6.0” Diameter,

Unreflected. . . . . . . . . . . . . . . . . . 47

Diluted Pu

2.0” Thick

Diluted Pu

4.5” Thick

Diluted Pu

7.5” Thick

Diluted Pu

2.0” Thick

Diluted Pu

4.5” Thick

Cylinders, 6.0” Diameter,

U(NO.3) Reflector . . . . . . . . . 48

Cylinders, 6.0” Diameter,

U(*O.3) Reflector . . . . . . . . . 49

Cylinders, 6.0” Diameter,

U(*O.3) Reflector . . . . . . . . . 50

Cylinders, 6.0” Diameter,

ThReflector . . . . . . . . . . . . 51

Cylinders, 6.0” Diameter,

ThReflector . . . . . . . . . . . . 52

7
IIIB7

IV

VA

VB

TABLES (Continued)

7.5” Thick Th Reflector .

U-233 Metal Spheres . . .

Pu or U-233 Metal Spheres

U(~93) Metal Spheres . .

Diluted Pu Cvlinders. 6.0” Diameter,

.*..* ●

✎✎☛✎☛ ●

Within

● **** .

.

.

●

Pu Metal Cylinder Within U(93.2) Metal

Cylinder, Thick U(N) Reflector . . . .

REFERENCES. . ● . . . . . ● . . . . . . . ● ●

.

●

●

✎

✎

.

.

.

.

.

.

.

.

.

.

Page

. 53

. 54

. 55

. 56

. 57

.

..

8

I

I

.

.’
-,

-.

INTRODUCTION

Numerous Los Alamos critical mass data have been

published only as points on curves, frequently after adjustment to “standard” conditions (e.g., to uniform values of

U235 enrichment and density), and usually without indication

of reliability. Under these conditions, original data tend

to become lost. It is the purpose of this compilation to

retrieve original critical masses and to give some means of

judging the quality of measurements.

Indexes of accuracy are probable error, if it has been

estimated, the maximum mass of fissile material used in the

measurement, or the maximum central-source neutron multiplication attained. For nonhydrogenous systems a multiplication of 10 usually corresponds to a core mass that is 70%

to 80% of critical, 20 corresponds to 85% to 90% of the

critical mass, 50 corresponds to 93% to 97%, and 100 corresponds to 96-1/2% to 98-1/2%. Generally, the probable

error in critical mass is about one-quarter of the difference

between the critical mass value and the maximum mass

employed. This estimate may be valid down to an indicated

probable error of 1% to 2%, beyond which the probable error

is usually controlled by the precision with which the composition and geometry of the system can be described.

Maximum multiplication is not a reliable index of accuracy

for hydrogen-moderated assemblies because of the severe

influence of neutron-spectral distortion.

Not included in this compilation are several critical

assemblies that cannot be described adequately by simple

entries in tables (e.g., assemblies with nonuniform cores).

Also omitted are a few critical mass estimates for which the

maximum mass used was less than three-quarters of the

critical value.

The following symbolism appears in the tables of

critical masses:

.

9
#-

m-Ccritical mass of core

m

max -

maximum mass used, in same units as mc

.

M

max -

maximum central source neutron multiplication

attained

hc - critical height of cylindric core

d- diameter of core

LxHxW- length times height times width of

parallelepipeds

P - density I

w/o - weight percent

v/0 - volume percent

U(93) - enriched uranium containing 93 w/o U

235

U(N) - uranium with natural isotopic composition

.-

,L

.

10
.

E+

=4

iii M

l-l z

t-. 

N

.P

(nww.

!-4

l-l.

u)

-H0 .m

In

l-l

Cd.a . 11
5?

.5

..

In0Ino .

F10 . +0

o

9-I

o

q+

2

Ln

a)

(u

+J

IQ

co.

l-l

d

o“

CQco

0° o“m

co. 0

I

iim

.s

in

c)

12
-!

?-.

TABLE 1A3

U(93.3) - U(N) MSTAL CYLINDSRS, 15.00” DIAMSTER, UNRSFLECIWD

Indicated layers, combinations of 0.3 cm thick U(93.3) and U(N), 0.6 cm U(N) or 1.5 cm U(N), start

with U(N) at bottom and end with portion of sandwich at top

Average composition is that of final stack

Corrected for influence of supports of split stack

Communicated by G. A. Jarvis

average

composition

u (93.3)

U (86.4)

u (83.4)

U (80.5)

u (77.7)

u (75.1)

u (70.5)

U (65.5)

U (64.4)

U (56.6)

u (57.l)C

u (50.5)

u (50.7)C

u (47.0)

u (47.1)

U (44.2)

U (38.0)

U (31.6)

U (28.9)

U (23.9)

U (21.3)

u (19.3)

repeated layers,

thickness (cm)

3) ufX)- ~ —

0.3

3.6

2.4

1.8

1.5

1.2

0.9

3.6

0.6

2.4

2.1

1.8

1.5

0.6

0.3

1.2

0.9

0.3

0.6

)

[1

0.3

0.3

0.3

0.3

0.3

0.3

0

0.3

0.3

0.3

0.3

0.3

0.3

1.5

0.3

1.5

1.5

1.5

1.5

0.6

0.3

1.5

1.5

0.6

1.5

()

1.5 b

0.3

1

)

1.5 b

0.6

)

1.5 b

0.9

F(total U)

(g/cm3)

18.06

18.08

17.95

17.98

17.98

16.19

18.16

16.33

18.21

16.37

18.34

18.35

16.44

18.42

18.25

18.49

18.49

18.51

18.32

18.65

18.62

18.66

h=

(in.)

3.18

3.36

3.50

3.60

3.70

3.77

4.00

4.05

4.34

4.60

4.66

5.25

5.25

5.53

5.61

5.92

7.02

8.23

9.63

11.73

14.15

17.85

he/d

0.212

0.224

0.233

0.240

0.247

0.252

0.266

0.270

0.289

0.306

0.311

0.350

0.350

0.369

0.374

0.394

0.468

0.548

0,642

0.782

0.943

1.190

a Corrections not as detailed as those for next-to-last item in Table IA1

m

c

(kg U235)

155.2a

152.1

151.6

150.8

149.8

149.1

148.2

140.8

147.6

138.5

141.2

140.9

142.2

138.8

139.8

140.1

142.9

139.2

147.5

151.6

162.6

185.8

b

The 1.5 cm U(N) plate was at base of stack; it alternates with the thinner

Successive sandwiches

c Extra U(93.3) plates at top of stack

U(N) in

(kgm?s)

151

146

146

146

146

146

146

136

142

136

137

137

141

134

134

137

140

135

144

149

155

175

.-

. 13
0

,-4

m

N

.

10

N

,+

m

.

Y a

.

.-l

0

m 0

.-$

v

coo

. .

4

a

WEI

InIn

.

.-l

m

!3

mnv
J

-.

n

.

‘2

Lo

x

m“

s

‘7

0.

15
#-

TABLE IB3

MISCELLANEOUS ENRICRED U METAL, U(N) Reflector

reference core

a

b

c

(14) annulus, 12.25” o.d. x 6.00”

id. x 3.01” high, stack of

1/2” and 1/4” thick rings

U(93.4), 5(U) - 18.7 g/cm3

(14) annulus, 12.25” o.d. X 6.00”

id. x 2.03” high, stack of

1/2” and 1/4” thick rings

u(93.4), F(u) - 18.7 g/cm3

(15) pseudocylinder, 13.74” av

dia x 12.00” av composition:= 18.1 v/O U(93.6),

7 - 3.38 g/cm3; 13.6 v/O

U(N), T - 2.58 g/cm3; 11.8

v/o Fe, 7 - 0.92 g/cm3;

52.3 v/o Al, T - 1.40 g/cm3;

4.2 V/O void

refleotor

1.00” thick, F - 19.0 g/cm3,

completely envelops core

3.00” thick, ~ - 19.0 g/cm3,

completely envelops core

kg :35

77.2 ~ 0.3

(mmax > mc)b

52.2 k 0.3

“’’ma. - 51.6)

pseudocylinder 5.0” av 93.0

thickness, T - 18.9 g/cm3 (Mmax - 225)

Unlisted, is a nonuniform assembly of mixed plates and rings of U(93.4) and U(N) that

enclose a near-central cylindrical cavity, 15.0” dia x 11.8”; outside dimensions of

the assembly are 21.0” dia x -.21” high (S. J. Balestrini, G. A. Jarvis, J. D. Orndoff,

December 1961). Average composition bounding cavity is U(27), -.4-1/2” thick U(N) rings

form tOD and bottom of cylinder. At critical, the total mass is -1400 kg U(N) and 339

kg U(93_.4). Uncorrected-for l/4° thick steel-plate

Corrected for small gap between assembly halves

Average thickness of core discs, blocks, and shaped

-“0.3”, Fe -0.25”, Al -0.9”

supporting portion a~ove cavity.

Al fillers: U(93.6) *0.4”, U(N)

16

.
. . .

0“m

m“ 00

m.

N0“

gA“

8-

‘1

17
a

(1 .

.-..

18
-.

..

TASLE ICI

HIGSLY 624RIC3!ED U M22AL, RsFLEmOR OF Ti, Al, A1203, MC, 9s , OR 6e0

,.

-.

r. f shape

(11) cylinder

(11) cylinder

(19) sphere

(11) cylinder

(11) c~linder

(11) cylinder

(11) cylinder

(11) cylinder

(11) cylind=r

(11) sphere

(11) sphere

(11) sPhere

(11) cylinder

(11) cylinder

(12) cylinder

(12) cylinder

(12) cylinder

(12) cylind=r

(12) cylinder

(11) pse.dosphere

(11) Pswdoephera

(10) psoudospbere

dimensions

(1..)

5.25 dia,

held - 1.61’

S.2S dia,

he/d - 1.3!3m

(llemting

shells)

5.25 dia.

h=/d - 1.59’

5.25 dia,

he/d - 1.35’

5.35 dia,

h=/d - 1.40’

5.35 dim,

he/d - 1.14a

5.2S dia,

held - 1.66s

5.25 dia.

h=ld - 1.46%

(nesting

shells)

(nemti.g

shells)

(nesting

shells)

5.2S dia,

h=/d - l.lOa

5.2S dis,

he/d - 0.90’

15.00 dim,

he/d - 0.131

15.00 dia.

h=/d - 0.090

15.00 di.,

he/d - 0.068

1s.00 dia,

h=/d - 0.053

15.00 dia.

he/d - 0.042

(1/2,,m n

blocks) i

(1/2- . “

blocks) A

(1/2,!❑ l”

blocks)

material

U(93.3)

U(93.3)

Ll(93.lS)

U(93.3)

U(93 .3)

U(93 .3)

U(93 .3)

U(93.3)

U(93 .3)

U(9S.9)

U(93.9)

U(93.6)

U(63 .3)

U(93 .3)

U(93.4)

U(93 .4)

U(93 .4)

U(93 .4)

U(93.4)

U(94)

U(94)

U(S2 .7)

5 (total u)

(CA?)

18 .7S

18.75

18.40

16.75

18.75

18.7$

18.75

18.75

18 .7s

18.s

18.75

18.6

18.75

18.75

17.7

17.7

17.7

17.7

17.7

18.7

18.7

17.8

reflector

n.t=rial

Tib

Ti b

Al (2014)

Al (2S)

Al (22)

‘1203

A1203

Mu (FS-1)

w (rS-l)

9.

64

Za

se (qw)

w (qw)

90

E.0

9a

&

94

Seo

B@

S.30

shspe

cylinder

cylinder

sphere

cylinder

cylinder

cylinder

cylinder

cylinder

cylinder

sphere

sphere

sphere

cylinder

cyltnder

cylinder

cylinder

cylinder

cylinder

cylinder

P.eudOsPh.re

Ps.udosphere

(24” cube)

thickness

(i”.)

0.Soo

1.000

2.610

i 0.03

0.500

1.000

0.500

1.000

0.500

1.000

1.6s

1.69

4.64

0.500

1.000

1.00

2.00

3.00

4.00

S.oo

2.35 .“

3.5 .“

3 (tot.1)

4@3-

4.50

4.50

2.82

2.70

2.70

2.76

2.76

1.77

1.77

1.64

1.64

1.64

1.84

1.64

1.60

1.60

1.60

1.80

1.80

2.69

2.69

-2.69

me

(IQZ U235,

52.4 i 0.6

45.0 t 0.1

34.71 i 0.1

52.0 f 0.6

44.1 50.1

45.5

37.2

54.2 + 0.7

47.7 i 0.3

22.2 * 0.2

21.6

13.1 i 0.2C

38.69 i 0.1

29.26 i 0.1

93.9 i 0.9

84.9 i 1.0

49.0 * 1.0

37.6 i 0.S

30.4 k 0.S

19.7

1s..5

10.3

m

—m..

16

125

170

17

200

-.100

.150

13

34

100

24

143

4s0

210

25

23

35

13

15

8s

105

critical

● Cor= of dl.ws 1.30’, to 0.075°, thick; ❑= corrected empirically for incidental reflection,

and 0.05 i“.3 central c.. ity

diaphragm supporting p.rt of sssemhly,

b Composition 98.5 w/o T;, 2.5 ./0 Cr, 1 w/o Fe

c With 0 .010,,Cd between core a“d reflector, m - 14.0 kc U335 (Mmax - 21)

c

d Uncorrected for 0.06 in.3 ce”trnl source cavity
-------

TAHLK 1C4a

HIGHLY 6NRIC212D U METAL, CT3UPL2T’6 GRAPHITE R3YLEC1’13R

Graphito is trade C3-212 except as noted

core

dimensions r (total u)

m f shape (in. ) material (g/cm3) —

(20) sphere

(20) ●phera

(20) sphara

(20) =Phera

(20) sphere

(20) cylinder

(20) pseudoc ylinder

(20) cylinder

(20) cylinder

(20) cylinder

(20) cylinder

(20) cylinder

(20) pseudocyllnder

(20) pseudocylinder

(11) cylinder

(11) cylinder

(12) cylinder

(12) cylinder

(12) cylinder

(12) cylinder

(21) cylinder

(14) annulus

a Uncorrectedfar O.0S

(nesting

ahells)a

(nestinK

Sh.lls) ~

(nesting

shells) *

(nestin

shahs) f

(nestin

shahs) s

3.25 dia,

held - 2.9S=

9.62 ~V dia

he/d - 1.85~

3.98 dia,

he/d - 1.30=

4.7S dia,

he/d - 0.S15=

5.50 dia,

he/d - 0.49S=

6.375 dia,

h=/d - 0.345=

7.50 dia,

he/d - 0.235=

h - 1.50,

he/d - 0.177d

h - 1.00,

h=/d - 0.081d

S.2S dia,

he/d - 1.42°

S.25 dia,

he/d - 1.16°

3.24 dia,

he/d - 6.79

3.24 din,

he/d - 4.97

S.24 dia.

he/d - 4.41

15.00 dim,

he/d - 0.073f

&?-dA~i92g

12.25 o.d. X

6.00 id. X

2.66

U(93.9)

U(63.9)

U(93.9)

U(93.9)

U(93.9)

U(93 .7)

U(94)

U(93.7)

U(93 .7)

u(93 .6)

U(94.0)

U(94.0)

U(94.0)

U(64.0)

U(93.3)

U(93 .3)

U(93.2)

U(93.2)

u(63.2)

U(93.4)

U(93.4)

U(93.4)

h.3 central scarcecavity

16.7

1s.7

18.4S

16.7S

16.5

16.5

18.7

16.5

16. S

16.5

18.5

18. s

16.7

18.7

16 .7S

18.75

16.7

18.7

16.7

17.7

16.7

16.7

reflector

sphere

sphere

sphere

sphere

pseudosphereb

pseudosphereb

pseudosphereb

pseudosphereb

pseudosphereb

pseudosphermb

pseudosphereb

pseudosphereb

pseudosphereb

pseudosphereb

cylinder

cylinder

cylinder

cylinder

cylinder

cylinder

cylinder

(envelOPs

core)

tbicknesa

(in. )

2.00

4.00

6.00

8.00

17 av

17 av

17 av

17 av

17 av

17 *V

17 ● v

17 av

17 av

17 ,V

0.s00

1.000

4.65

5 .7s

6.25

7.00

2.00

2.00

1.67

1.67

1.67

1.67

1.66

1.66

1.66

1.66

1.66

1.66

1.66

1.66

1.66

1.66

1.67

1.67

1.60

1.60

1.60

1.60

1.66

-..1.67

‘c

k “235,

29.6 * 0.3

24.3 i 0.2

21.5 * 0.2

19.s * 0.3

17.0

22. s

20.1

18.3

17.5

ls. s

20.0

22.7

24.6

34.6

46.35 i 0.2

37.71 * 0.1

51.7 * 0.9

37.9 i 0.7

33.6 i 0.7

52.1 * 1.0

50.0

73.3 i 0.3

b Pil.-grade graphite surrounds ..5’0thick c2-312

= Interlocking rings; uncorrected for O .06 in. 3

central source cavity

d Poraed of 1/2” min blocks

9 Cure of disc= 1.20” to 0.075” thick: m corrected empirically for incidental reflection, diaphragm supporting pari

of assembly, and O .0s in. g central cavfty

f Core of O.3 cm thick plates; empirical correction for diaphragm supp-arting part of assembly

g ~re of 0.315,. thick plates: empiric.1 correction for diaPhragm suPPOrthC Part Of ~ms~bly

Mmax

58

150

150

42

46

17

40

109

62

7s

107

1s0

90

200

51

>500

233

13s0

460

20

16

..

.

. .

..

.
-’

x.; c:a

0

t.00

ti.

t-w

CTJ

0. a

+4

0. mm

In

*

.+mm

*UYID . .

.

CDmw

21
0

.::m

UI

r-l

0’).

In00 .

In

In.

f+m

la

0) n .

.:Msmm%

~2

L1

a)

-U1

a.c

a)al

U2+

+!-4

N.N0m m m m m w : : : : : N N m N . . . . 0 0 0 0 an .

+1-4

.rlrn

GnMmm

G.C

00

u+

=Ul .
-.

TA6LE IC6m

HIGHLY ENR1CH2L2U k15TAL, CC41PLETE lfEf’LEC7UR OF lf,.0 OR POLY&HfYLW6

“.

.

see also first lccm of Table 11F3

CO,.

dimensions T (total U)

re f shape (in.) (g/”~) —

(25) sphere

(25) sphere

surrounded

by O.O1Oss Cd

(20) sphere

(24) sphere

(24) hollow sphere,

filled with H20

( 24) h.allow sphere,

filled with If20

(24) hollow sphere,

filled with X20

(20) cylinder

(20) cylinder

(20) cylinder

(20) cyll”der

(20) cyl i“der

(20) cylinder

(21) a“nulu.

(26) bomisbell,

S.gmented

(12) cylinder

(12) cylinder

(11) cylinder

(11) cylinder

(12) cylittd.ar

(12) cylinder

(14) . . ..1.s

(shells)

0.83 id.

(shell=)

0.63 id.

(nostin

shells) s

(nesting

shells)e

3.60 id.

4.00 id.

4.68 id.

3.98 dia,

he/d - 1.90”

4.75 di. ,

b=/d - 0.98”

5.S0 dia.

held - 0.66=

6.375 dia,

h /d - 0.46”

c

7.00 dia,

he/d - 0.365”

7.S0 dia.

he/d - 0.300”

6.14 o.d. x

3.05 id. x

5 .75~

12.0 o.d. ,

10.0 id.

3.24 die,

Ll=/d - 12.2

15.00 alla,

he/d - 0.082C

5.25 din,

he/d - 1.34d

5.25 dia,

be/d - 1.OOd

3.24 din,

he/d - 6.0

15.00 die,

he/d - 0.095”

12.25 o.d. x

6.00 id. x

2.20

.ater$al

U(93 .9)

U(93.9)

U(93 .9)

U(63.9)

U(93.9)

U(93 .9)

U(93.8)

U(93 .7)

U(93.6)

U(93 .6)

u(94.0)

U(94 .0)

U(94.0)

U(93.15)

U(93.5)

U(93 .2)

U(93 .4)

U(93 .3)

U(93 .3)

U(93 .2)

U(93.4)

U(93.4)

18.5

18.4

18.5

18.5

18.5

18.5

18.5

18..5

18.5

18.5

16.5

18.5

16.5

18.75

18 .7S

18.7

17.7

18.75

18.75

18.7

17.7

18.7

reflector

.

material shaPe

H20 cylinder

H20 cylinder

f120 cylinder

H20 sphere

H20 sphere

H20 sphere

QO sphere

H20 cyll”der

Ifzo cylinder

H20 cylinder

H20 cylinder

H20 Cylinder

H20 c,li”der

H20 Cylinder

H*O cylinder

IfZo cylinder

U20 cylinder

pc.lyethyle”e cylinder

Polyethylene cyli”dm’

POIYethyle”e cyll.der

polyethylene cylinder

polyethylene (envelops

core)

thickness

(in.)

>12

>12

>12

3.25

14.6

14.4

14.3

>12

>12

>12

>12

>12

>12

>12

>6

>12

>12

0.500

1.000

4.00

2.00

3.00

‘3 (g/cm )

1.00

1.00

1.00

1.00

1.00

1.00

1,00

1.00

1.00

1.00

1.00

1.00

1.00

1.00

1.00

1.00

1.00

0.921

0.921

0.92

0.92

0.92

(kKmc&)

23.4

32.9

23.2

23.5

2s.1

26.3

27.7

26.7

23.7

24.4

25.9

27.7

29.0

28.6 i 0.5

56

93.2 + 5

59.0 * 0.S.

43.7

32.7

61.3 ~ 0.9

68.4 * 0.8

56.6 * 0.3

a Uncorrected for O .0S i“ .3 central source cavity

b water fills .“””1”s

c Core of 0.3 cm plates; empirical correction for’ sm.11 source c.vity and diaphrngm s.ppc.rti”g part of assembly (not used with

H20 reflector)

—

uMax

49

32

154

35

40

80

19

101

200

1s0

108

53

35

20

43

170

140

140

161

79

@

c

d

Empirical cm-roctlo” for sm.11 c.. tr.l cavity ●“d support effects

e Corrected for small gap 1“ fi”.1 c.anfigur.ticm

23
.-

.

TABLE IC6b

HIGHLY ENRICHED U METAL, COMPLETE REFLECTOR OF

Paraffin reflector cylindrical, >8” thick, 7 =

PARAFFIN

0.89 g/cm3

core

m

(kg U;35)

dimensions

(in.)

(nesting

shells)a

(shells),

0.83 id.

3.25 dia,

he/d = 4.4b

3.98 dia,

he/d = 1.80b

4.75 dia,

he/d = 0.915b

5.50 dia,

he/d = 0.605b

6.375 dia,

he/d = o.45b

7.50 dia,

he/d = 0.280b

T (total U)

(g/cm3 )

18.5

M

max

62

ref

(20)

(25)

(20)

(20)

(20)

(20)

(20)

(20)

shape

sphere

sphere

cylinder

cylinder

cylinder

cylinder

cylinder

cylinder

material

U(93.9) 22.2

U(93.9) 18.5 22.8

35

69

U(93 .7) 18.5 11

U(93.7) 18.5 25.0

22.2

77

U(93.8) 18.5 108

U(93 .8) 18.5 22.4 123

U(94.0)

U(94.0)

18.5 24.5 200

18.5 26.9 86

Uncorrected for 0.05 in.3 central source cavity

0.05 in.3 central

a

b

Interlocking rings *0.4° thick, uncorrected for

source cavity

24
. .

TABLE IC6C

HIGNLY ENRICN20 U METAL, PARTIAL R.8FLE~R oF H20,POLYETHYLENE,LUclTE,oR pARAFFIN(5)

Reflector same diameter as core

core of 0.3 cm plates and rings; n= cOrrected empirically fOr diaphra~ suPPOrtlng Part Of

assembly, for incidental reflection, and for small central source cavity

cylinder

dia (in. )

a

b

c

15.00

21.00

15.00

21.00

15.00

21.00

15.00

21.00

15.00

21.00

15.00

21.00

15.00

21.00

15.00

21.00

15.00

21.00

15.00

21.00

15.00

21.00

material

U(93 .3)

u(93.2)

U(93.3)

U(93 .2)

U(93.3)

U(93.2)

U(93.3)

U(93.2)

U(93.3)

U(93.2)

lJ(93.3)

U(93 .2)

U(93.3)

U(93 .2)

U(93.3)

u(93.2)

U(93 .3)

U(93.2)

U(93.3)

U(93.2)

U(93.3)

U(93.2)

7 (total U)

(g/cm3)

17.9 * 0.2

18.2 * 0.2

17.9 * 0.2

16.2 k 0.2

17.9 * 0.2

18.2 k 0.2

17.9 * 0.2

16.2 i 0.2

17.9 * 0.2

18.2 k 0.2

17.9 * 0.2

18.2 * 0.2

17.9 * 0.2

18.2 f 0.2

17.9 * 0.2

18.2 f 0.2

17.9 * 0.2

16.2 t 0.2

17.9 * 0.2

18.2 * 0.2

17.9 * 0.2

18.2 k 0.2

reflector

—

material

H20a

H20a

polyethylene

polyethylene

polyethylene

polyethylene

polyethylene

polyethylene

polyethylene

polyethylene

polyethylene

polyethylene

polyethylene

polyethylene

polyethylene

polyethylene

polyethylene

polyethylene

lucite

lucite

paraffin

paraffin

surfaces

reflected

top plane

top plane

top plane

top plane

top plane

top plane

both planes

both planes

top plane

top plane

top plane

top plane

top plane

top plane

top plane

top plane

top plane

top plane

top plane

top plane

top plane

top plane

thickness

(in. )

6.oO

6.00

1.00

1.00

2.00

2.00

2.00

2.00

3.00

3.00

4.00

4.00

6.00

6.00

8.00

8.00

10.00

10.00

6.00

6.00

6.00

6.00

P

.@@

1.00

1.00

0.925

0.925

0.925

0.925

0.925

0.925

0.925

0.925

0.925

0.925

0.925

0.925

0.925

0.925

0.925

0.925

1.18

1.18

0.87

0.87

(kgm;235)

109.6 * 0.4

188.5 i 0.7

126.2 ~ 0.5

228.4 + 0.6

113.6 * 0.4

196.5 + 0.6

73.1 * 0.3

117.4 * 0.3

109.3 * 0.4

190.3 f 0.6

106.5 i’0.4

168.5 ~ 0.6

106.7 * 0.4b

187.9 i 0.6C

108.5 + 0.4

187.8 k 0.6

108.5 f 0.4

187.6 + 0.6

106.4 f 0.4

182.1 * 0.6

109.2 t 0.4

188.5 k 0.6

Empirical correction for effecz of 1/16” Al tank containing water, via influence of the tank

containing lucite

Critical mass 129.0 i 0.5 (Mmax - 170) when 0.015” Cd between core and reflector

Critical mass 228.4 * 0.6 (Mmax - 38) when 0.015” Cd between core and reflector

Mnax

250

99

167

125

57

35

73

90

77

280

75

160

99

195

110

245

120

102

52

74

130

49

25
0

u

mmmm

. . . .

‘?? 77

.

..

.

■ ncl emu

26

.
mbmt-wv

? m.rmwmo

v Nmwwom

s.

0 0“ 0“ 0“ 0“ 0“

mm4mw

mwe+mmtskam

Ntnm

NNmmrJ*lne

. . . .

00000” 0”0”0”

.’

-.

t-*mmt-mmo

t-omkommm

m

. . . . .

-lNNmmw” Lc”w”

k2m *w-#

mol*Nm

. .

Nm”*”m”ln

m.m.

mmmdomc.am

*. NLom L-lol

. . . . .

,+

me4NF10mbuY

+,+,-(,+

6

mama)

Lmlomln

0“ 0“ o“

.Qllnm% . . .

N,-400

o“

mm

InIn

0“

mcmmmm

Inlnln!nln

. . . . .

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lnlnlnlolnln loo

muitn.mmmmm

. . . . . .

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w ‘w. .

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.$ Uaa w’-??

. . . .

.NAooo”

wvmtneamcnm

. . . . . .

meati.-idoo”o”

Zzzzz

.A.-!..I”A.A

27
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ml+. .

@aN

mm

mw

*A

tntn

mm. .

mm

cow

00.

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mao

mm.

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4A

03UY

de!. .

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Com

*I+

au).

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mm

00.0 0.

NI+. .

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aaFmm

eJm*

mcoco

meat- . . .

000 . .

0!0!+

CONCD

..

W“wa) .

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1+m:

I-Id

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ti.mm~mw . . .

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m. . .
I+ WF+N

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A.-l

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oil-l

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aoinoY

. . . .

0000

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tndwmo

ua~mmmo

Fioeaw

mm f+mm cobmt-

. . . . . . . . .

Ooddd dsamm

mmcnm

*moo

ml-e

. . . .

oodm

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+ramw 1+1-i r+rt

. . . . . . . .

0000 0000

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180. . mmmmm. . . .

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F

mmmm =mam G

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o“oo o”_” mmd o 0 ~

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.

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m

m

u

s

al

w

m

Co Wloco

. . . .

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I-4towol

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< ..0 ...
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31
88

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*“80..m*v2

)4~

l-l 0. 0m

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u)

l-( qm

l-l 8

0

01-( 0. .

co

Ua

00).bN

c%*m. vav.0

1+0mN

I-4.*a>

‘a5xm0..9mm

00

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?-l.

co

lom.

l-(

t-Nd*m . ..

32
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ar+A

1+

. 0

z

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l-l wNx

1+x

In

. Q

Ind

to

.

?+

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l-l

xN

m“ 0

1+

In

33
wm

.WmN

Inxmx. 0m

(nm .

10+ . mn

,+0m

l-l nx

xx . .

la

I

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1-

al. d0

mxwK

b“w @a.N

.-l N2

N.

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Is. mmmm

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m

l-l

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35
1+

r-l

l-l

t-m. N

cox

1+*

1+

co

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d

co

x

t-0 .

In l-l

co

1+.

l-t m

x

In

1+

InH :mNx

1+

Inm

mx

l-l

x . . . Nm . Nm

l-l

In

N

●

mw

1-.

a)

co

m.

In

1+

10.

r+0+

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N

t-

.

1+N

0 . m

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N

.

m

In

N

.

m

In

N

Inm. 0

N%.

0“mm

tmdCD. 0

zmm

oo“

i-l No

?+mo . 0oNs0 . 0

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co0

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cow

00

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37
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1%$w

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1+m. 0

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38 .
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..

TABLE 11?,1

DIFFUSE u(93.1) RSFLSC7ECI BY TR1= D20 OR *

“235 enrichment of all uranius is 93.15 W)O

(CAVITY AsssmwIEs)

cm-e cylindric reflector

cavity cylinaer tllickness Interior

ref dimensions (in. ) fuel material

—

(in. )

(3s) 40 dia X 40 0.003” U foil covering D20 (99.2 w/0) 20

cavity surf ace, on av

0.05” Al support

(35) same except 4“ dia sxisl channel through bottrn reflector

(35) same except 6’” dia axial channel through bottom reflector

(35) same except 8“ dla axial channel through bottom reflect~

(35) 8ame except 9“ din axial channel through bott.m reflector

(35) same except 10,, dia axial channel through bottom reflectOr

(35) same except 23.9 kg D20 (12,, x 12’” CY1) mt cavity center (no channel)

(35) 40 dia X 40

(36) 15-1/2 dia X 31

(36) 15-1/2 dla x 31

(36) 15-1/2 dia x 31

(36) 1S-1/2 dia X 16

SIX 40” dieca Of

0.035’? av o foil 8“

apart along cmwity

axle, on 1/16’” Al plates

0.022” a“ u foil

covarinc cavity surface, on 1/16” Al

supper t

0.01s” ,“ u foil

covering cavity surface, on 1/16” Al

support

0.6 o.d., 0.25 id.

graphite - 22 w/o U

rods, distributed

uniformly within

cavity, parallel to

axis

0.6 c..d.o 0.25 id.

graphite - 22 v/o U

rods, distributed

ullifOTDIY within

cavity, parallel to

D20 (99.2 w/o) 20

se (F - 1.77 g/cm3) 14 wall, 18 top,

15 bottc,

se (7- 1.79c/c.%16. S wall,

18 top, 15 bottom

s.9(F-1.79 g/cm3) 16.5 wall,

18 top, 15 bottom

se (75- 1.77 c/cm3) 14 wall, 18 toP,

30 bottom

liner

1/8’” Al, ~V

1/8%1 Al, av

1/16” Al

1/16” Al

(,s :3’)

6.00*

6.06

6.09

6.19

6.26

6.40

5. 60b

7 .B7C

11. od

7.74

7 Se, f

g.9K

axis

a After correction for Al cavity liner and fuel support, m= - 5.33 kg; 6.93 kg of 0.003,, foil covers the. cav%ty

completely

b

Corrected for effect of Al container for central D20

c After corractlon for Al cavity liner and fuel support, m= -7.0 kg

d &.rrected (-O ,04 kg) for Al fuel support

e Corracte.d (-0.03 kg) for Al cavity liner

M.,x

critical

critical

Critic.1

critical

critical

critic.1

critical

critical

56

100

130

138

f

8 - 7.30 kg when fuel concentrated tc...rd Outmide of c.vity,m - 8.60 kg when fuel concentrated long axis; with 14,,

r~flector wall, m= - 8.99 kg when fuel concentrated toward outc%de of c.vity

C Corrected (-O .02 kg) for Al cavity liner

.

39
.ai

. .

“.

*- ~.

x Ci

.-I .,-(

Ou 0:

0

m-mm

0 0.;

o“~ 0:

“i
-.

10

c1

0

b

t-$ Wb

. . . .

AN

Wo

&

. .

mm

f-il.-l

00

tnm

00

.

o“ o
wm+

o“s

. :A . 0

o

‘m

.N@

+10.mam .

0N. m

(0u0 .a

0“

In

In

1+

.

l-l 0

l-l Nmm0w . S0

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-.

REFERENCES

(1) G. E. Hansen, Status of Computational and Experimental

Correlations for Los Alamos Fast-Neutron Critical

~ssemblies, Ph ysics of Fast and Intermediate Reactors,

AEA9 vi enna (1962).

(2) G. E. Hansen and D. P. Wood, Precision Critical-Mass

Determinations for Oralloy and P1 utonium in Spherical

ball Oy Tampers, LA-1356 Revised (to be issued).

(3) J. D. Orndoff and H. C. Paxton, Measurements on

Untamped Oralloy Assembly, LA-1209 (February 1951) .

(4) V. Josephson, R. W. Paine, Jr. and L. L. Woodward,

Oralloy Shape Factor Measurements, LA-1155 (August

950) ●

(5) G. E. Hansen, D. P. Wood and B. Pe&a, Reflector Savings

of Moderating Materials on Large Diameter U(93.2%)

S1abs, LAMS-2’(44 (June 1-!%?2).

(6) H. C. Paxton, Bare Critical Assemblies of Oralloy at

Intermediate Concentrations of U-235, LA-16T1 (May

954) ●

(7) private communication, D. M. Barton (September 1958).

(8) V. Josephson, Critical Mass Measurements on Oy in Tu

and WC Tampers, LA-1114 deleted (May 1950) .

(9) J. D. Orndoff, H. C. Paxton and G. E. Hansen, Critical

Masses of Oralloy at Reduced Concentrations and

Densities, LA-1251 (May 1951) .

(10) Private communication, C. P. Baker (December 1947).

(11) G. E. Hansen, H. C. Paxton and D. P. Wood, Critical

Masses of Oralloy in Thin Reflectors, LA-2203 (July

58) ●

57
REFERENCES (Continued)

(12) G. E. Hansen, H. C. Paxton and D. P. Wood, Critical

Plutonium and Enriched-Uranium-Metal Cylinders of

Extreme shape, Nuclear Scl. and Eng. ~, ~0-b’/~

(1960) ●

(13) J. J. Neuer Critical Assembly of Uranium Metal at an

Average U23~ Concentration of 16-1/4%, LA-2085

(January 937 ) .

(14) Private communication, J. J. Neuer, G. A. Newby,

H. C. Paxton and T. F. Wimett (March 1954).

(15) Private communication, H. C. Paxton and C. B. Stewart

(May 1953).

(16) Private communication, D. P. Wood, L. C. Osborn and

B. Pe%a (April 1960).

(17) Private communication, V. Josephson and R. W. paine,

Jr. (March 1951).

(18) Private communication, J. C. Hoogterp and D. P. Wood

(September 1955).

(19) D. P. Wood and B. Pe%a, Critical Mass Measurements of

Oy and Pu Cores in Spherical Aluminum Reflectors,

AMS-2579 (June 1961) .

(20) E. C. Mallary, Oralloy Cylindrical Shape Factor and

Critical Mass Measurements in Graphite, Paraff in, and

Water Tampers, LA-1305 (0ctober 1951) .

(21) J. C. Hoogterp, Critical Masses of Graphite-Tamped

Heterogeneous Oy-Graphite Systems, LA-1732 May 954) .

(22) Private communication, G. A. Jarvis (November 1961).

(23) private communication, D. p. Wood (October 1961).

(24) Private communication, F. F. Hart and C. B. Stewart

(December 1953).

.,

.4

.-

(25) Private communication, R. W. Paine, Jr., D. P. Wood

and R. S. Dike (April 1951).

58

u

. .
.

1.

.-. . . .

.

-.

. .

(26)

(27)

(28)

(29)

(30)

(31)

(32)

(33)

(34)

(35)

(36)

(37)

(38)

REFERENCES {Continued

F. F. Hart, Safety Tests for Melting and Casting

Oralloy, LA-1623 (December 1953).

Private communication, K. Gallup, G. E. Hansen

(July 1951).

Private communication, R. E.

1951) .

Private communication, E. C.

Private communication, J. J.

R. H. White and T. F. Wimett

Private communication, G. A.

Schreiber (September

Mallary (March 1952).

Neuer, H. C. Paxton,

(March 1954).

Jarvis (June 1963).

H. Iskenderian and C. C. Byers, Physics Calculations

on Four Los Alamos Graphite Moderated Critical

Assembl ies, Trans. ANS l_, No. 1, p. 149 (June 1958);

also private communication, C. C. Byers (September

1957) .

G. E. Hansen, J. C. Hoogterp, J. D. Orndoff and

H. C. Paxton, Beryllium-Reflected, Graphite-Moderated

Critical Assemblies, LA-2141 (0ctober ●

Private communication, S. J. Balestrini (November

1963) .

Private communication, C. C. Byers (March 1962).

Private communication, G. A. Jarvis and C. C. Byers

(October 1961).

R. N. Olcott, Homogeneous Heavy Water Moderated

Critical Assemblies, Part 1, Experimental, Nuclear

Sci. and Eng. ~, 32’i-341 .

G. E. Hansen and W. H. Roach, Interpretation of

Neutron Resonance Detector Activities in Critical

Uranyl Fluoride - Heavy Water Solutions, Proc.

Brook haven Conf. on Resonance Absorption of Neutrons

in Nuclear Reactors, Upton, New York, BNL 433 (C-24),

pp. 13-25 (September 1956); also private communication,

C. C. BYers (January 1956).

J59
.

.1

REFERENCES (Continued)

(39)

(40)

(41)

(42)

(43)

(44)

(45)

(46)

(47)

(48)

(49)

(50)

(51)

Los Alamos Scientific Laboratory of the University of

California, An Enriched Homogeneous Nuclear Reactor,

RSI 22, 489-499 (July 1951) ; also L. D. P. King,

Wate~Boilers. LA-1034 (December 1947).

R. E. Carter and J. C. Hinton, Water Tamper Measurements, LA-241 (March 1945).

J. C. Allred, P. J. Bendt and R. E. Peterson, critical

Measurements on U03-H3P04 Solutions, Nuclear Sci. and

%ng. ~, 498-500 (1958) .

Private communication, J. C. Allred, P. J. Bendt,

H. C. Paxton and R. E. Peterson (April 1953).

G. A. Linenberger, J. D. Orndoff and H. C. Paxton,

Enriched-Uranium Hydride Critical Assemblies, Nuclear

Sc i . and Eng. ~, 44= (1960) .

private communication, M. G. Holloway and C. P. Baker

(December 1947).

H. C. Paxton and G. A. Linenberger, Polythene-25

Critical Assembly and Neutron Distribution Studies,

LA-749 (September 1949).

J. C. Hoogterp, Critical Masses of Oralloy Lattices

Immersed in Water. LA-2026 (November 19553 .

G. A. Jarvis, G. A. Linenberger, J. D. Orndoff and

H. C. Paxton, Two Plutonium-Metal Critical Assemblies,

Nuclear Sci. and Eng. ~, 525-531 (1960) .

E. A. Plassmann and D. P. Wood, Critical Reflector

Thicknesses for Spherical u233 and PuZaY Systems,

Nuclear Sci. and Eng. ~, 615-620 (1960) .

private communication, D. P. Wood and C. C. Byers

(December 1960).

Private communication, H. C. Paxton (October 1951).

D. P. Wood, C. C. Byers and L. C. Osborn, Critical

Masses of Plutonium Diluted with Other Metals,

Nuclear Sci. and Eng. _~ .

● I

4

I

I

. .

. I

I

. .

60
REFERENCES (Continued)

(52) Private communication, G. E. Hansen (October 1963).

(53) Private communication, H. C. Paxton, G. E. Hansen,

D. P. Wood and E. A. Plassmann (May 1960).

(54) D. M. Barton, W. Bernard and G. E. Hansen, Critical

Masses of Composites of Oy and Pu-239-240 in Flattop

Geometry, LAMS-2489 (~ecember 1960 ) .

61

-.