5. Materials Surveillance Program for the RA10 Research Reactor

RAUL VERSACI; GRACIELA BERTOLINO; ALEJANDRO YAWNY; GUILLERMO ARIAS; HERMAN BLAUMANN

San Carlos de Bariloche

Congreso; IGORR; 2014

CNEA

P { margin-bottom: 0.08in; direction: ltr; color: rgb(0, 0, 0); line-height: 115%; widows: 2; orphans: 2; }P.western { font-family: "Calibri",sans-serif; font-size: 11pt; }P.cjk { font-family: "Calibri",sans-serif; font-size: 11pt; }P.ctl { font-family: "Times New Roman",serif; font-size: 11pt; } A Surveillance Program is part of a more general Ageing Management Program and its objective is the assessment of the structural integrity of critical core materials components in order to ensure a safe and reliable long term operation. Neutron irradiation affects ductility, tensile and toughness properties of materials in general and might result in irradiation induced growth in Zirconium base structural materials. Corrosion and irradiation assisted stress corrosion cracking effects should also be considered. It is worthwhile to remark here that even when there is a standard practice for the design of a surveillance programs for light water moderated nuclear power reactor vessels (ASTM E185), there is a lack of general guidance in the case of research reactors. Therefore, ad-hoc surveillance programs have to be developed for research reactors considering the peculiarities of each design. In the present case, the most exposed critical components were firstly identified. Thereafter, the critical components were categorized in those that are replaceable or no replaceable along the expected life of the reactor. The materials of interest are Zircaloy-4, Zr-2.5 wt.%Nb, Stainless Steels and Aluminum Alloys. The evaluation of the effects of irradiation is followed by periodically removing (5, 10, 20, 30 and 40 years) capsules containing tensile, fracture toughness CT and small punch testing specimens representative of the different materials and thermomechanical conditions (plates, forgings, welds and HAZ material). Dosimeters are placed within the surveillance capsule and evaluated to determine the associated neutron fluence at the specific location within the vessel and time of extraction. Specimens will undergo post-irradiation testing in a hot cell facility to determine their mechanical properties (and dimensions). The obtained values will be compared with the original values and the predefined design limits to evaluate the operational margin of safety. In summary, the present paper describes the methodology of the implemented surveillance program, the test specimens, their locations and the tests to which they will be subjected.