cording intervals of 12 hours and 60 hours were used. with tape transport speeds of 0.25 and 0.05 in/sec.
respectively.
These speeds were accurate to =2 percent for the entire’recording interval.
were of identical construction with the exception of the drive motors.
stack having a capacity of 14.000 ma-hr powered each recorder.
The 12-hour recorder was driven by a
2-watt motor operating at a speed of 6.000 rpm and regulated by a centrifugal governor.
chronometrically governed motor rotating at 900 rpm operated the 60-hour recorder.
utilized gear reduction and worm-gear drive.
Both recorders
A single 6.?-volt mercury-battery
A 0.75-watt,
Both recorders
The tape was guided in the conventional manner.
friction plates on the feed spindle established an average tape tension of about 4 ounces.
Metal
Contacts on the
recorder turned off the instrument when a conductive section of tape at the end of the reel passed over
them to cause a circuit closure. Both recorders were developed at U.S. Naval Radiological Defense Lab~
oratory (NRDL) in conjunction with the Precision Instruments Company, San Carlos, California.
ree toe
The dose increments chosen for the low- and high-range ionization chambers were 0.243 mr and 0.243
r, respectivels. At the maximumintensity of each range, the maximum-usable pulse packing on the tape
nent of
only to the particular detector orientation and gamma energy chosen for the calibration (Appendix B).
nizaties
As radiation data was recorded on the two channels of the three-channel tape, bits were recorded on
the third channel at 3.75-second intervals to establish a time reference for data reduction. The time bits
4) contris
were generated by a cam-operated switch driven by a low-power. 6-volt, direct-current. chronometrically
alumins
d detect =
governed motor. The accuracyof these pulses was 40.5 percent. The timer was manufactured by the
Haydon Companyand was used because of its known accuracy and high reliability.
nprove .
srover: .
the ce -
limited the recycling rate of the electrometer to 100 cps (87,500 r/br) fur the 12-hour recording interval
and to 20 eps (17,500 r/hr) for the 60~hour interval. These dose increment and dose-rate values apply
.
The function of the control circuit was to start and to turn off the instrument.
Power to all the motors
and to the filaments was controlled by means of a latching relay. This relay could he activated locally by
a switch on the instrument or remotely by a contact closure through a cable into the instrument. The instrument could be turned off by deactivation of the relay with the switch on the instrument or by the tapeactuated turnoff switch on the recorder.
izatyen.
ovelin.
seillat .
onchi: { th
4
«
;
Mercury batteries were used to power the motors and the filaments in order to take advantage of the
high current capacity and flat-discharge characteristics these batteries offer. In addition, a mercury
battery with very-lowcurrent drain was used in the electrometer-calibration circuit to restrict calibration
shift to less than +1 percent during the expected life of the battery. Chamber bias and transistor bias
were supplied by carbon batteries. With the exception of the motor battery. the minimum battery life was
vefare:
i
in excess of 250 hours.
2 pale
2
6¢-hour recorder in excess of 80 hours without a battery change.
However, the 12-hour recorder could be operated in excess of 26 hours and the
stant
z
Tr
q
4.3
‘
&
:
All components were designed to operate under the following maximum conditions: (1) a shock of 15 g
at 11 msec in all planes, (2) vibrations of 12 g at frequencies up to 45 cps in all planes, (3) temperature
within the detector of 120 degrees F, (4) temperature within the main instrument assembly at 155 degrees
F. (5) ambient relative humidity of 100 percent, and (6) a static overpressure of 5 psi. During the opera~
{hos
tonal t
transwhic:
eve?!
DESIGN LIMITS FOR OPERATION
tion, satisfactory performance beyond these limits was frequently observed.
rove)
mCte Fr
A.
eal’.
SHOCK MOUNTING
The GITR instruments were installed throughout the three target ships.
Because of the high shock ex-
\ grade
pected on these platforms, all instruments were shock mounted for approximately 6 inches of deflection.
ed by
An eight-point suspension from steel springs in lines through the center of gravity of the instrument was
$756.
O00 te reuite
respons
used to support the main instrument assembly.
%
The natural frequencyof the suspension was about 5 cps.
The detector unit was supported from four springs in a horizontal plane through the center of gravity of
the unit.
The suspension had a natural frequency of 7 cps and allowed 5 inches of deflection.
‘
Aj REMOTE-STARTING CIRCUIT
i
The limited recording time of the instruments and the requirement for unattended operation necessitated
remote triggering of the instrument installations.
A shipboard system was designed to meet this require-
h stan’:
us’
ment (Figure A.5).. The system consisted of the EG&G tone receiver and minus-5-minute relay, which was
connected to the project control panel and relay system. The relay system consisted of latching relays,
un:
which were apaced throughout the ship.
When activated by the timing signal, each latching relay started
‘