[en] External dose needs to be estimated for the radioactivity discharged into the canal, as it constitutes one of the pathways of exposure to the public. Two activities are considered here: i) a walk along the bank of the canal ii) and the walk on the bridge. A concentration of 1 Bq/l is assumed here for the gross beta activity for the estimation of the dose conversion factor. A canal of width 14.39 m and the depth of 2.5 m is considered for this study. Length of the canal is taken to be infinite. Canal side wall is assumed to be the 25 cm thick concrete. Two points are selected, one on the bank, and the second on a bridge 1 m above the top surface of canal water. Dose Conversion factors for the person moving on the Bridge (at one meter above the water surface) and standing on bank of canal is estimated by using the QAD CG code for "1"3"7Cs. Dose conversion factors for the location mentioned above are found to be 1.11E-10 Sv/hr/(Bq/l) and 1.55 E-11 Sv/hr/(Bq/l) for bridge and bank of canal respectively. (author)