Assessment of damage domains of the High-Temperature Engineering Test Reactor (HTTR)

•We developed an adequate model for the identification of damage domains of the HTTR.•We analysed an anticipated operational transient, using the HTTR5+/GASTEMP code.•We simulated several transients of the same sequence.•We identified the corresponding damage domains using two methods.•We calculated exceedance frequency using the two methods.

This paper presents an assessment analysis of damage domains of the 30 MWth prototype High-Temperature Engineering Test Reactor (HTTR) operated by the Japan Atomic Energy Agency (JAEA). For this purpose, an in-house deterministic risk assessment computational tool was developed based on the Theory of Stimulated Dynamics (TSD). To illustrate the methodology and applicability of the developed modelling approach, assessment results of a control rod (CR) withdrawal accident during subcritical conditions are presented and compared with those obtained by the JAEA.