ORNL-1771 - Oak Ridge National Laboratory

TIME (rnin)
PERIOD ENDING SEPTEMBER 10, 7954
m
ORNL-LR-DWG 266i
0 10 20 30 40 50 60 70
DISTANCE FROM HtACTOR (cml
Fig. 13.7. Decay of Air Glow and Reactor Gamma Fig. 13.8. Attenuation in Water of Radiation
Rays. Causing Air Glow.
of light. This large uncertainty is primarily at-
tributable to the low sensitivity of the eye-equiva-
lent photomultiplier. A more detailed discussion
of these preliminary values will be given in a
forthcoming report. 8
FUEL ACTIVATION METHOD FOR POWER
DETERMINATION OF THE ARE
E. B. Johnson
When the ARE goes into operation, many measure-
ments of its performance will be made. Among
them will be the power level at which it operates,
which will be measured in more than one way. A
method suggested by J. L. Meem is based on the
measurement of the relative activity of fuel samples
exposed in the ARE and in a known flux in another
reactor (BSR). An experiment has been initiated
at .the BSF to implement this suggestion.
8F. C. Maienschein et al., iMeusurc7nents o/ u l?t?acto~-
Induced Air Glow, ORNL CF-54-9-1 (to be issued).
The activity resulting from the irradiation of
fissionable material is not easy to predict because
of the large number of isotopes for which calcu-
lations would be required. However, for identical
flux, exposure time, and waiting period after
exposure, the specific activity of two samples
should be the same. Furthermore, at low neutron
fluxes the activity should be proportional to the
flux.
It is contemplated that the ARE will be operated
at a nominal power level of approximately 1 w for
1 hr, that it will then be shut down, and that a
sample of the irradiated fuel will be withdrawn for
counting and analyzing. The ARE experimental
progrom will then proceed as scheduled. A decay
curve will be run on this fuel sample from the ARE
and compared with the decoy curve obtained on a
similar fuel capsule irradiated for the same length
of time in the BSR in 01 known neutron flux of about
the same magnitude. From the relative activity of
the two samples, the operating power of the ARE
173