Procedure for Critical Experiment

This is Copy 53 of __________, Series A.

Pile [unclear] Research
Addison Wesley Pub Co
Cambridge 42, Mass


Clifford Beck
with best regards
Raymond L Murray
A. C. Menius Jr.
H. A. Lamonds

Raymond L. Murray & Operating Staff
of Raleigh Reactor

July 10, 1953

Department of Physics
School of Engineering
North Carolina State College
Raleigh, North Carolina

Went Critical at
00:59 Sept 5, 1953.
with 787.95
gm U235 (93%)


Raymond L. Murray & Operating Staff
of Raleigh Reactor
July 10, 1953
General Notes

[page 2]

Phase 1 - Check-out of Equipment

The completion of each item below will be reported to the Director and checked
off on his list, with the name of the person performing the duty.

[page 2 verso]

[page 3]

[page 4]

List channels by name, location + detector locations
, type of trips.

Phase 2 -- Addition of Material During Counting Period

In this phase, the bulk of the U235 is added to the core. Predictions of
the critical mass Mc are made after successive increments. The number of counts
taken over a fixed period increases as the multiplication of neutrons increases.
Thus 1/C approaches zero as the mass approaches Mc. Graphs of 1/C are repeatedly
extrapolated to obtain improved estimates of Mc,

The enriched uranyl sulfate is supplied in individual bottles with U235
contents as listed

#1 200 grams
2 200
3 200
4 100
5 100
6 50
7 50
8 50
9 25
10 10
11 10
12 4
Total 999 grams

The chemical concentration is approximately 600 grams per liter. The total
volume of solution as shipped is thus 1.67 liters. The final solution volume for
the critical experiment is to be close to 13 liters. If the critical mass turned
out to be 715 grams, this would mean that about 12 liters of water are needed.
At full power an excess of 75 grams over the critical mass will be present. The
ratio of hydrogen to uranium atoms then should be between 450 and 500. The
addition of water and sulfate solution should be made in such a way that the atom
ratio Nh/Nu is essentially fixed.

Assume that 430 is near but below the proper Nh/Nu ratio. To maintain this,

[page 5]

It is to be noted that there is noise in the switches
on console + thus spurious counts in scalers. Overload
in A.C. lines.

the water addition per 100 grams must be 1.5 liters. In the event that the
critical mass is larger than 715 grams the water content should be kept low during
the initial stages.

(Predicted critical mass 715 50 grams) 12.46 12.7

*B10#1 **B10#1
B10 #2 B10 #2
Fission chamber BF3

[page 6]

Phase 3 -- Fine Adjustment of Mass Using Source and Control Rod

[page 7]

Phase 4 -- De-activation

[page 8]

Approval of Procedure by Participants:

C. K. Beck C. K. Beck
J. T. Lynn J. T. Lynn
A. P. Sanders A. P. Sanders
J. C. Lundholm J. C. Lundholm, Jr.
H. A. Lamonds H. A. Lamonds
A. C. Menius, Jr. A. C. Menius, Jr.
R. L. Murray R. L. Murray

[page 8 verso]

#3 + #9 reserviced so that will reset.