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personnel access to the area where the filter is
located. By the end of run 11 (May 1967) the
filter was plugged again, and periodic venting of
the coolant system through an auxiliary line
(L-536) was required to keep the loop overpressure
below 10 psig.
During the shutdown between runs 11 and 12,
the filter was replaced again, and a minor piping
modification was made to permit the coolant off-
gas activity monitoring to monitor gas vented
through line 536. Be€ore this change, any activity
release would have been detected and stopped by
another monitor on the combined fuel and coolant
off-gas, but identification of the source of the
activity would have been more difficult. No
activity has ever been detected in the coolant
off -gas.
Cooling Water Systems
A. 1. Krakoviak
The cooling water systems performed satishctorily
during this report period. The systems
functioned relatively trouble free except for a
few Leaks. In July a 15-gpd leak from the treated
water system was detected and was traced to a
faulty pressure-relief valve in the line leading to
one of the reactor cell coolers. Replacement of
the farilty relief valve restored the system to
normal oper- ‘i t. Ion.
Space Coolers. - As reported previ~usly,~ leaks
have occurred in the reactor cell space coolers
at the brazed joints on the brass tubing headers.
During the scheduled shutdown at the end of run
11, both space coolers were leak-tested. One
cooler (KCC-1) leaked less than 125 cm3/day
and was not replaced; however, the other (RCC-2),
which leaked at the rate of 9 Iiters/day, was replaced
with a cooler whose headers and nipples
were fabricated of copper. Copper weldments
were used on the new cooler instead of the brazed
joints .
Radiation levels around the removed unit were
sufficiently low that it could be disassembled
directly. The radiator was the most radioactive
component, with readings up to 1000 rniIlirerns/hr
at contact. (The radiation was very soft and
caused no contamination problem.) This unit was
discarded. However, the fan motor was retained
71bid., p. 32.
for possible future use, and the new fan, motor,
and radiator were mounted on the original frame
for installation in the cell.
Reactor Cell Annulus. -- Sometime prior to or
during run 11, the fill line to the biological shield
plugged, and water additions to the reactor cell
annulus were made through the level measuring
line. Since the plug in the fill line could not he
cleared, the overflow pipe from the cell arinulus
was modified to also serve as a fill line.
Steam Dome Feedwater Tanks. - Water is dumped
automatically from a feedwater tank (FWT) to a
steaiii dome if cooling of a fuel drain tartk (FD)
is required aftet a fuel drain. During run 12, sr!iall
amounts of water Erom FWT-1 had randomly appeared
in the steam dome of FD-1, causing a temperature
decrease in the fuel drain tank. To ensure
that this drain tank remained available for a
possible emergency drain, the water was removed
from the feedwater tank, which is now in normal
service after having a faulty temperature switch
replaced.
Component Cooling System
P. 11. Ilerley
Although some difficulties were encountered,
the component cooling system operated satis-
factorily during this report period. The two main
blowers (CCP-1 and CCP-2) operated 1536 and
2375 hr tespectively; CCP-2 has operated for a
total of 3340 hr without a failure.
The discharge check valve on CCP-2 was re-
placed and the belt drive was tightened as part
of the prevenf.ive maintenance program. There was
no indication o€ any significant aging of the sili-
cone rubber in the removed check valve.
Trouble was encountered in the CCP-1 oil cir-
culating system. First, a loose tubing connection
caused the loss of ‘\2 gal of oil during run 12;
this irregularity was easily repaired. Then, Fol-
lowing the run 12 shutdown, intermittent law-oil-
pressure alarms again occurred. An investigation
indicated no significant 10s:; of oil, but a slow oil-
pressure response was observed when the blower
was started. The suspected oil pump and pressure-
relief valve on CCP-1 were replaced with spare
units to correct the trouble. The removed pressure-
relief valve was found to be re1 ieving before the
normal oil pressure developed. In spite of these