Memorandum from R. L. Murray and A. C. Menius, Jr. to C. K. Beck
1 p.
April 18, 1951

April 18, 1951

TO: C. K. Beck
FROM: R. L. Murray and A. C. Menius, Jr.
SUBJECT: Rate of Power Rise with Control Rod Removal

1. Removal of the control rod in 10 minutes is estimated to be a safe rate.

2. The rate at which the reactor power P increases with rod removal speed vr
is found to be always smaller than that predicted from the steady-state
power-rod position curve, ie

After a time delay characterized by a time (of the order of 10
seconds at the middle of the range) where 1e is
the average neutron lifetime, [alpha] is the temperature coefficient of reactivity,
and To is the initial difference in temperature of solution and coolant,
the power rise rate approaches the predicted rate, .

Thus a test is provided for any pre-assigned rod speed. The maximum slope o
the curve above is

Thus at a speed such that the rod is removed in 10 min (600 sec), then

at other points on the curve dP/dx is smaller, of course, and thus dP/dt
is smaller.

The analysis loading to those conclusions is given in the Appendix.