The focus in the WATCHEM project has been in development
of in situ methods (a) to study oxidation of fuel
cladding alloys and (b) to study optimisation of
passivation (i.e. Hot Conditioning) of PWR reactor
circuit surfaces prior to first fuel loading.
The Controlled Distance Electrochemistry (CDE) method
has been shown to be reliable and to give consistent and
repeatable results both in BWR and in PWR conditions.
Comparisons of the effects of elevated Li+ (PWR) and K+
(WWER) concentrations on fuel cladding oxidation were
performed as part of this project. In studying the
sensitivity limits of the CDE method the effects of F-
concentration in the beginning of cycle conditions of
WWER on Zr-1Nb alloy oxidation were found to be
negligible at levels below 100 ppb.
Based on a literature study the optimal water chemistry
conditions in PWRs for Inconel 600 and 690 materials are
0.5-1 ppm Li+ and 25-30 ccH2/kgH2O. There is a
considerable uncertainty in determining the effect of
boric acid and the minimum required hot conditioning
time. Two new methods were developed in co-operation with
Bhabha Atomic Research Centre (BARC), India, to study the
optimisation of the hot conditioning procedure and
verified for carbon steel under PHWR water chemistry
conditions. Preliminary studies with Inconel 690 under
PWR conditions are underway.
|Title of host publication||SAFIR2010: The Finnish Research Programme on Nuclear Power Plant Safety 2007-2010 |
|Subtitle of host publication||Interim Report |
|Place of Publication||Espoo|
|Publisher||VTT Technical Research Centre of Finland|
|Publication status||Published - 2009|
|MoE publication type||Not Eligible|
|Series||VTT Tiedotteita - Research Notes|