Hydrogen water chemistry effects on BWR radiation buildup, Volume 2: Loop tests to study dissolution and deposition of oxides. Final report

Alternating between Normal Water Chemistry (NWC) and Hydrogen Water Chemistry (HWC) leads to relocation of activation products around the circuit of BWRs. Work is described here where five powders of spinel oxides Fe3O4, NiFe2O4, ZnFe2O4, α-Fe2O3, FeCr2O4, were labelled with 57Co and then exposed to both different chemistries. Released activity was collected on high temperature filters and measured. In addition the spinel powders were analysed by Moessbauer spectrometry as both absorbers and sources. The work showed that more activity was released from NiFe2O4 and ZnFe2O4 in HWC than NWC, but no structural changes were observed. Very little activity was released from FeCr2O4 in either chemistry, more activity was released from Fe3O4 in NWC than HWC and significant oxidation to α-Fe2O3 took place in NWC. The 57Co from the labelled α-Fe2O3 was found to be labile in NWC; it was n ot in the form of CoFe2O4. This oxide (α-Fe2O3) lost much more activity than other oxides. Activity adsorbed on loop surfaces within the sample oven formed products which were not re-released to any significant extent in either NWC or HWC