Study On The Compatibility Of 15-15Ti With Simulated Fission Products And Lead Coolant

In the defense-in-depth concept,the cladding material is the first barrier to retain the radioactive fission products from the outside environment.Its integrity is crucial to the safety of the reactor.Compared to thermal reactors,the cladding material in fast reactors will be exposed to more aggressive environment: higher irradiation dose(100-200 dpa)and higher working temperature(400-800?).Furthermore,the cladding will even face the corrosion of corrosive lead or LBE in LFR at high temperature.15-15Ti type stainless steel has been chosen as cladding material for many fast reactor projects including CFR600 fast reactor in China.However,the data on the FCCI phenomena of 15-15Ti are rare and data of the compatibility between 15-15Ti and liquid lead are insufficient.In order to address these technique gaps,three tests are performed in this project.Test I and II are focused on the compatibility between cladding materials and fuel,whereas test III focuses on the compatibility between cladding materials fission products,and coolant in the accident scenario.The main conclusions are as follows:(a)Under lower oxygen potential,Te seems to be the most problematic element compared to Cs and I both for 15-15Ti(12R72)and CN15-15Ti.Whereas cesium may play the main role under higher oxygen potential.(b)Deep grain boundary attacks induced by Te has occurred and the products in the grain boundary were assumed to be Cr2Te3.Besides,the corrosion process was proposed in the report.(c)In Test ?,locally Ni dissolution and Pb penetration(roughly 30-40 ?m)occurred on 15-15Ti samples.This research extends our knowledge of FCCI phenomena of 15-15Ti austenitic cladding material at high temperature.Additionally,the present study confirms previous findings and contributes additional evidence that suggests Te might be the most problematic element under lower oxygen potential.Regarding CN15-15Ti,although the current study of CN15-15 is based on a small group of specimens,FCCI test was performed on CN15-15Ti the first time.This study will serve as a base for future studies of CN15-15.Besides,this research contributes to existing knowledge of compatibility of lead coolant and 15-15Ti...