796 POJE, GINN, AND O'CONNOR 



As in field studies, problems are encountered in assessing 

 entrainment impact by these laboratory data. The possible syner- 

 gistic relationship of the stresses must be quantified. 



We have investigated the responses of striped bass and carp larvae 

 to simulated power-plant condenser-tube passage by using a unique 

 experimental apparatus that closely approximates the thermal, 

 hydraulic, mechanical, and biocide stresses of condenser tubes. 



MATERIALS AMD METHODS 



Simulator Operation 



The power-plant condenser- tube simulator can subject 

 entrainable-sized organisms to variable flow velocities, temperature 

 changes (AT), biocide concentrations, and pressure changes. All 

 stresses occur simultaneously during passage through a condenser 

 tube of a length, diameter, and construction comparable to that in a 

 power plant. The apparatus consists of a source-tank system, 

 circulation pump, injection station, hypochlorite pumping system, 

 dual condenser tubes to which heat is applied, and collection tanks 

 for each condenser tube (Fig. 1). 



A variable-speed feed pump (pump 1 in the figure) supplies water 

 from any available water source (the simulator is portable) to a 

 950-liter reservoir (A), which is held at a constant static head (±50 

 mm of water) by an overflow drain. The centrifugal circulation pump 

 (pump 2) propels water through the system at precisely controlled 

 flow velocities over the range from 0.5 to 3.0 m/sec. 



Organisms are injected into the flow of the simulator in an 

 isolation loop (B), and loop pressure is equalized to that of the 

 circulating water. Organisms are entrained and accelerated instanta- 

 neously to the selected flow by operating ball valves that shunt the 

 entire flow through the isolation loop. 



The water then enters a vertical section of pipe which divides at a 

 y junction (C). Pressure, temperature, and flow are monitored by a 

 gauge before the split. Dual sections of clear plastic piping allow the 

 investigator to view organisms after the split. The biocide system 

 feeds into the main simulator flow above the split. The biocide 

 injection system (D) consists of a 200-liter reservoir tank that feeds a 

 variable speed diaphragm pump (pump 3). The flow of biocide can 

 be manipulated to supply either one or both condenser loops. 



The vertical piping constricts into 25.65-mm ID condenser tubes 

 above the inlet from the biocide system. The tubes are composed of 



