IMPINGEMENT MITIGATION RESEARCH 



Research directed towards improving our understanding of the factors 

 which influence impingement, and ultimately to reduce losses of fish due 

 to impingement, began in 1973. These special research projects are 

 listed below with a brief summary of results. 



Diel Patterns in impingement - This study divided the regular 24-h 

 sampling scheme into two 12-h periods. Collections revealed that most 

 impingement occurred at night (NUSCo 1977). Similar studies at other 

 power plants resulted in similar findings (PSE&G 1980; Boston Ed 1982; 

 FloPo 1977; PG&E 1980; JCP&L 1981). 



Storms - Impingement records between 197 6 to 1981 were examined to 

 see if storms (expressed as high wind conditions) caused an increase in 

 impingement. A statistically significant difference in impingement 

 before and after storms was noted (NUSCo 1981a). 



Cooling Water Flow - Examination of historical impingement data 

 together with EDAN data revealed that impingement totals at Units 1 and 

 2 were found to be significantly correlated with condenser cooling water 

 flow (NUSCo 1982) . 



Fish Deterrance - Since 1975 many techniques and devices have been 

 tested or employed in an effort to reduce impingement levels at Units 1 

 and 2. Among them were: 



1) Electric Fish Screens (NUSCo 1976), 



2) Fish Barrier Nets (NUSCo 1976), 



3) Acoustic repulsion (NUSCo 1976), 



4) Underwater light (NUSCo 1976), 



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