Computation of the fluence of fast neutrons in the reactor pressure vesselof Unit I of Kozloduy NPP

The procedure of computation of the fluence of fast neutrons in the pressur e vessel of the WWER-440 reactor of Unit I of the Kozloduy NPP, Bulgaria, b y the method of the discrete ordinates using the neutron transport code TOR T and the cross-section library SAILOR is outlined. The principal results f or cycles 16, 17 and 18 are reported, together with a comparison between me asured weight specific activities of Mn-54 (a product of the reaction Fe-54 (n,p)Mn-54) in shavings taken from different locations on the inner surface of weld no.4 of the pressure vessel of unit I after the end of cycles 17 a nd 18 and the corresponding predicted values on the basis of the computed f luence of fast neutrons at these locations. (C) 1999 Elsevier Science S.A. All rights reserved.