Plant Operating Standard
CC-CI-49 Containment Cooling and Containment Isolation
- 1. One fan is operating with the second fan serving as a standby. The capacity of the
operating fan is sufficient to maintain the upper containment temperature below 140F and
the lower containment temperature below 115F.
- 2. Both main cooling coils are operating. These coils maintain the average upper containment
temperature below 140F, the lower containment below 115F, and the dome below 150F.
- 3. The containment isolation system is in AUTO position for normal operation (including
the steam stop valves).
- 4. The oxygen concentration in the containment vessel atmosphere is being maintained at about
8% by inerting with nitrogen.
[The original plan was for the containment vessel to remain inerted, and for
personnel to wear self contained breathing apparatus, "gas diving", when entering it. There
was an accident,
described in "One Upon A Nuclear Ship", and someone nearly died. After that the procedure
was changed to purge the containment vessel before entering, and then re-inert it after words.
This involved having a truck of nitrogen in one of the cargo holds, and running an additional
pipe to it.]
Minimum Condition for Reactor Operation
Containment Entry, Reactor Shutdown
- 1. The containment vessel must be purged at least one (1) hour prior to entry. The
containment purge valves must be closed at all times except when in use for their designed
purpose, and when so in use, will be attended in order that immediate closure can be made
if the need arises.
- 2. The air lock shall be used for normal access to the containment. Other hatches may
not be opened until sufficient time has elapsed since the shutdown to permit replacing the
hatch prior to fuel melting in the event of a loss of reactor coolant.
- 3. Entry to the containment through the airlock must be controlled as follows:
- a. With primary system temperature above 300F, one door of the airlock must be closed
at all times.
- b. With primary system temperature below 300F, but with the primary system pressure
above 250 psig or up to and including 2200 psig, both airlock doors may be open, but they
shall be continually manned to effect closure if necessary.
- c. When the primary system temperature is less than 200F, the various containment
hatches may be open under the conditions stipulated in paragraph 2.
- 4. Initial entry is to be made under the auspices of the Health Physics group; full
protective clothing and face masks are to be worn until atmospheric conditions are established
and Health Physics surveys made. They will establish the ambient and surface radiation
levels which exist, and the concentration of carbon dioxide and oxygen in the containment
atmosphere, as well as the presence of any airborne radioactivity.
- 5. All subsequent entries will be made in accordance with the requirements of
Radiation Control Work Permits, which are to be required for this entry.
- 6. Personnel shall never entry or remain in the containment alone (except for the
brief period required for an individual to pass through the airlock).
My text copyright 2020 Tommy Johnson, all rights reserved. I believe the Savannah documentation is property of
MARAD or the US government.