MetaHeuristics
Previous Projects

Modeling active cobalt concentration using Metacomp



Cobalt 60 corrodes/erodes from various primary circuit components and may deposit in activated form in out-of-core components, where radiation fields are produced that may impact maintenance. In Boiling Water Reactors, Zinc is often injected in feedwater to control cobalt deposition in external loop. In same cases, the cobalt concentrations decrease after zinc injection is initiated, but start to build up again over many fueling cycles. Metacomp was used to develop a neural model to predict cobalt concentrations in the external loop using water chemistry data in the reactor and feedwater, and analysis and fuel history. The model took into account time develop and could be inverted to tailor coolant chemistry to meet prescribed cobalt concentration targets over time. It was found that zinc additions had to be carefully regulated around optimum values for each fuel cycle to reduce cobalt concentrations.

 

Co-60 CONCENTRATIONS


60Co concentration in the reactor water. Data are compared with the results of NN3 in which the real value of 95*ZnFW-ZnRW and CoFW are used (labeled “n it 7771), and with the results of NN1, NN2 and NN3 combined (labeled “NN1+NN2+NN3”), in which the values of 95*ZnFW-ZnRW and CoFW are computed from NN1 and NN2. The value of the 60Co concentration is in Bq m-3. Time is in weeks. Data cover both training set (up to week 323) and test set (since week 324 on). The agreement is very good.