Project Presentation: WP3
RISK ANALYSIS FOR CRITICAL COMPONENTS (KTH, SCK•CEN, SINTEC, IDOM, VCE, SRS)WP3 activities are subdivided in the following 3 tasks:
Task 3.1: Sloshing effects and complex dynamic phenomena
Simulation of the dynamic phenomena in which local equipment response could undergo significant coupling with the overall motion of the reactor is carried out.
The sloshing effects in the isolated LFR concept are studied. Detailed, refined models of key components inside the reactor vessel will be realized for studying sloshing effects, moving for the response spectra at component locations produced in WP2. Gas entrapment and fluid structure interaction within the vessel of the studied LFR configuration are studied.
The complex dynamic phenomena related to the accelerator/reactor coupling are evaluated.
Task 3.2: Computation of risk
The task is devoted to the evaluation of the risk associated with the seismic motion for the studied reactor systems, with particular attention to (i) the seismic fragility evaluation, namely the probability of failure of a component (or structural element) and (ii) the evaluation of the risks related to the void entrapment into coolant and void transport to the core conditioned to the severity of the ground motion.
On the basis of experimental and numerical testing, limit state functions associated to both failure and “first-damage” conditions of selected key reactor components are studied. It will also set and calibrate simplified models of the reactor systems, suitable for the performance of a large number of seismic analyses on other components. On this basis a numerical procedure is developed, based on the Response Surface methodology, for computing the seismic fragility. It will develop efficient procedures for the refinement of Response Surfaces and for the evaluation of failure probability of systems under stochastic seismic excitation. The refinement procedure is based of the computation of risk, i.e. the convolution of seismic hazard and fragility, for prototype sites. The analysis, once set up the general procedure applicable to each reactor system, will be focused on all the abovementioned isolators as well as on the vessel of the LFR reactor.
A deterministic-probabilistic approach is applied for identification of the domain of seismic loading parameters where void entrapment into the coolant and risk related to voiding of the core and possible reactivity incretion is significant.
A risk management framework is provided for the lifecycle of the systems and their components. The model start with the planned resistance, allows periodic updating and issues warning in case those components reach critical safety levels. The effect of events will be considered by the assessment of monitoring results delivered from the planned operational monitoring systems.