Radioactivity transportation in the primary sodium circuit of pool type fast breeder reactor

A computer program 'SOLPREC-II' has been developed to estimate the production; transportation and deposition of radioactive corrosion products on the primary sodium circuit components of a pool type Fast Breeder Reactor (FBR). Following the model proposed by Polley and Skyrme, process of release and deposition is described in three steps: (1) diffusion through structural materials, (2) absorption and desorption on the interface between structural material and liquid sodium, and (3) diffusion through laminar layer of sodium flow. Transportation of radioactive corrosion products along the sodium flow is handled by solving the mass conservation equation in one dimension, using upwind scheme. Production of radionuclides is considered to take place at the core. Using the code, generation and distribution of long-lived γ-emitting nuclides such as 54Mn and 60Co can be estimated. This has been validated with the results of the Japanese sodium test loop, AMTL-I. It was then used to predict the deposition pattern in FBTR at IGCAR. Kalpakkam, Indian, for its real time operation for the period (1990-2002). Now the code is being extended to assess the deposition pattern for the pool type Prototype Fast Breeder Reactor, as shown in Fig. 1, being constructed at Kalpakkam. From the thermal hydraulic analysis of sodium flow, it is assumed that mixing at the core outlet, inlet and outlet of the IHX and pump is complete and uniform. The surface deposition density of the above nuclides at IHX and Pump for a 5-year envisaged operation campaign comprising 8 months at full power and 20 days shut down is presented. (author)