ORNL-2106 - the Molten Salt Energy Technologies Web Site

i
I
ANP PROJECT PROGRESS REPORT
two samples were taken from the same spool of
Teflon-insulated wire. One sample was the usual
length, 25 ft long, and the second was 50 ft long.
The two samples were installed at the same time
in hole 50-N of the ORNL Graphite Reactor. The
25-ft Teflon-insulated sample was instal led in the
same manner as in the previous experiments, with
no seal at the end. The 504 sample was doubled
back on itself so that both ends of the wire were
outside the reactor. The leakage between the
shield and the central conductor was measured to
be twice as large for the 50-ft sample as for the
25-ft sample. The photo-emf measurements on the
two wires were identical. It can therefore be
concluded that the radiation effects described
previously2* were due to bulk properties rather
than to end surface conduction or to air ionization.
5
4
x3 m
> -
+4
c z
W
LL m
2 2
t
0
I
Barriers
A 1N38A germanium point-contact rectifier was
exposed in a 2 x 106-r/hr Co60 gamma-ray source,
and the forward and reverse currents were measured
at 1-v bias. The behavior of the current is shown
in Fig. 4.2.14. These data are in qualitative
agreement with those obtained by Young.30 The
increase in reverse current, followed by a return
toward its initial value, is an effect not found in
reactor irradiation experiments because it occurs
at low total damage. As may be seen from the
change in forward current, the effect illustrated in
Fig. 4.2.14 would have occurred before the sample
30R. C. Young, Gamma Radiation of Crystal Diodes,
Wright Air Development Center, WCRT-TN-54-255 (Dee.
28, 1954).
~
I
IN38A-B
0 REVERSE CURRENT, pa
0 FORWARD CURRENT, ma x lo-'
IN38A-A
A REVERSE BIAS. NORMALIZED TO
- COMPARE WITd lN38A-B -
UNCLASSIFIED
ORNL-LR-DWG 13755
0 t 2 3 4 5 6 7 ( x IO7,
GAMMA EXPOSURE lrl
Fig. 4.2.14. Effect of Gamma Radiation on Conduction Through a Barrier. Germanium point-contact
rectifier 1N38A-B exposed to 2 x lo6 r/hr from Co6O source; 1N38A-A exposed to 2.5 x 105r/hrfrom
C060 source.
244
e
1