loop) generate steam. Water in the primary loop (fig. 17-4) is heated but not converted to steam. The water in the primary loop flows from the reactor  to  a  heat exchanger   called   the   steam   generator.   Here,   the high-temperature,   high--   pressure   water   in   the primary  loop  heats  the  water  in  the  secondary  loop until it becomes steam. The water in the primary loop then  returns  to  the  react  or  by  the  primary  coolant pump.  The  steam  generated  in  the  secondary  loop, which  is  not  superheated,  goes  to  the  turbine.  This portion of the secondary loop uses a condenser and a feed pump similar to the conventional steam turbine plant. The nuclear power plant has two primary ad- vantages—  infrequent  fueling  requirements  and  no need  for  combustion  air.  The  ability  of  the  plant  to operate    without    combustion    air,    as    previously mentioned, makes it ideal for use in submarines. The nuclear  power  plant  is,  however,  expensive  to  build and   extremely   heavy;   it   requires   highly   trained personnel for its operation. DAMAGE CONTROL An  area  of  engineering  that  should  by  no means  be  considered  secondary  is  damage  control (DC).  Damage  control  is  an  all-hands  evolution  on Navy ships that can never be overemphasized. DAMAGE CONTROL ORGANIZATION Damage    control    is    divided    into    two    phases- administrative  and  battle.  The  administrative  phase requires the efforts of all hands in establishing and maintaining material readiness conditions. (Material readiness means  all  equipment  aboard  ship  is  available and   in   a   working   condition   to   combat   any emergency.)   The   battle   phase   starts   after   a ship has received damage and must restore its offensive  and  defensive  capabilities.  All  hands must be trained in both phases if the ship is to achieve its damage control objectives. When  properly  carried  out,  the  first  or initial action taken helps reduce and confine any damage   received.   Strict   use   of   compartment checkoff  lists  ensures  the  full  protection  offered by each material readiness condition. Once   the   ship   has   been   damaged,   the ship’s     DC     organization     is     responsible     for restoring the ship to as near normal operation as possible. The ship’s engineer officer is responsible  for  the  operational  readiness  of  the DC  organization.  Under  the  engineer  officer  the damage  control  assistant  (DCA)  coordinates  the efforts of repair parties in the control of damage. These    efforts    include    controlling    the    ship’s stability;  fighting  fires;  repairing  damage;  and using    chemical,    biological,    and    radiological (CBR)  defense  measures.  The  DCA  also  ensures that  the  crew  receives  training  in  all  damage control  evolutions.  In  some  instances,  the  DCA and   the   engineer   officer   may   be   the   same person. Figure 17-4.—Naval nuclear power propulsion plant. 17-9