Irradiation Embritlement in Alloy HT-??9

Serrano De Caro, Magdalena¹ 

[1] Los Alamos National Laboratory

关键词: A CODES;    ALLOYS;    COMPUTERIZED SIMULATION;    COOLANTS;    CORROSION;    CREEP;    DESIGN;    DUCTS;    EMBRITTLEMENT;    FAST REACTORS;    FUEL ELEMENTS;    IRRADIATION;    LIFETIME;    LIQUID METALS;    PERFORMANCE;    PHYSICS;    RADIATIONS;    SATURATION;    STEELS;   

DOI  :  10.2172/1049989
RP-ID  :  LA-UR-12-24334
PID  :  OSTI ID: 1049989
Others  :  TRN: US1204583

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来源: SciTech Connect

【 摘 要 】

HT-9 steel is a candidate structural and cladding material for high temperature lead-bismuth cooled fast reactors. In typical advanced fast reactor designs fuel elements will be irradiated for an extended period of time, reaching up to 5-7 years. Significant displacement damage accumulation in the steel is expected (> 200 dpa) when exposed to dpa-rates of 20-30 dpa{sub Fe}/y and high fast flux (E > 0.1 MeV) {approx}4 x 10{sup 15} n/cm{sup 2}s. Core temperatures could reach 400-560 C, with coolant temperatures at the inlet as low as 250 C, depending on the reactor design. Mechanical behavior in the presence of an intense fast flux and high dose is a concern. In particular, low temperature operation could be limited by irradiation embrittlement. Creep and corrosion effects in liquid metal coolants could set a limit to the upper operating temperature. In this report, we focus on the low temperature operating window limit and describe HT-9 embrittlement experimental findings reported in the literature that could provide supporting information to facilitate the consideration of a Code Case on irradiation effects for this class of steels in fast reactor environments. HT-9 has an extensive database available on irradiation performance, which makes it the best choice as a possible near-term candidate for clad, and ducts in future fast reactors. Still, as it is shown in this report, embrittlement data for very low irradiation temperatures (< 200 C) and very high radiation exposure (> 150 dpa) is scarce. Experimental findings indicate a saturation of DBTT shifts as a function of dose, which could allow for long lifetime cladding operation. However, a strong increase in DBTT shift with decreasing irradiation temperature could compromise operation at low service temperatures. Development of a deep understanding of the physics involved in the radiation damage mechanisms, together with multiscale computer simulation models of irradiation embrittlement will provide the basis to derive trendlines and quantitative engineering predictions.