A Repairable Dynamic Event Tree for the safety assessment of a steam generator of a nuclear power plant

International audienc

A repairable dynamic event tree framework for the safety assessment of a steam generator of a nuclear power plant

Traditional Deterministic Safety Assessment (DSA) and Probabilistic Safety Assessment (PSA) of complex systems have been recently challenged by the excessive conservatism of DSA and the demanding treatment of uncertainties of PSA. In order to deal with these challenges, new methodologies have been developed which result from the integration of DSA and PSA methods for an Integrated Deterministic and Probabilistic Safety Analysis (IDPSA). In this work, we show the capabilities of a Repairable Dynamic Event Tree (RDET) who sets its basis on the traditional static Event Tree (ET) while focusing on the dynamic aspects of accident scenarios thereby described (e.g. timing and magnitude of occurrence of components failure events and repair), as an integrated methodology for IDPSA. We apply the framework of the RDET for the reliability assessment of a U-Tube Steam Generator (UTSG), in which we assume that four components can fail (with different timing and magnitude of failure) and can be repaired. The results of the RDET are benchmarked with those of a traditional ET and of a Repairable ET (RET)

DAE RespondER: The Emilia Romagna app for a regional "community saving lives" system

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The stroke mothership model survived during COVID-19 era: an observational single-center study in Emilia-Romagna, Italy.

Introduction A reduction of the hospitalization and reperfusion treatments was reported during COVID-19 pandemic. However, high variability in results emerged, potentially due to logistic paradigms adopted. Here, we analyze stroke code admissions, hospitalizations, and stroke belt performance for ischemic stroke patients in the metropolitan Bologna region, comparing temporal trends between 2019 and 2020 to define the impact of COVID-19 on the stroke network. Methods This retrospective observational study included all people admitted at the Bologna Metropolitan Stroke Center in timeframes 1 March 2019\u201330 April 2019 (cohort-2019) and 1 March 2020\u201330 April 2020 (cohort-2020). Diagnosis, treatment strategy, and timing were compared between the two cohorts to define temporal trends. Results Overall, 283 patients were admitted to the Stroke Center, with no differences in demographic factors between cohort-2019 and cohort-2020. In cohort-2020, transient ischemic attack (TIA) was significantly less prevalent than 2019 (6.9% vs 14.4%, p = .04). Among 216 ischemic stroke patients, moderate-to-severe stroke was more represented in cohort-2020 (17.8% vs 6.2%, p = .027). Similar proportions of patients underwent reperfusion (45.9% in 2019 vs 53.4% in 2020), although a slight increase in combined treatment was detected (14.4% vs 25.4%, p = .05). Door-to-scan timing was significantly prolonged in 2020 compared with 2019 (28.4 \ub1 12.6 vs 36.7 \ub1 14.6, p = .03), although overall timing from stroke to treatment was preserved. Conclusion During COVID-19 pandemic, TIA and minor stroke consistently reduced compared to the same timeframe in 2019. Longer stroke-to-call and door-to-scan times, attributable to change in citizen behavior and screening at hospital arrival, did not impact on stroke-to-treatment time. Mothership model might have minimized the effects of the pandemic on the stroke care organization

Pre-hospital ECG in patients undergoing primary percutaneous interventions within an integrated system of care: reperfusion times and long-term survival benefits.

Aims: Treatment delay is a powerful predictor of survival in STEMI patients undergoing primary PCI. We investigated the effectiveness of pre-hospital triage with direct referral to PCI, alongside more conventional referral strategies. Methods and results: From January 2003 to December 2007, 1,619 STEMI patients were referred for primary PCI at our cathlab through two main triage groups: i.e., 1) following pre-hospital triage (n=524), 2) via more conventional triages (n=1,095) represented by the S. Orsola-Malpighi hospital emergency department triage (hub hospital) and local hospital triage. Pre-hospital diagnosis was associated with a 76 minute reduction in pain-to-balloon time (143 [107-216] vs. 219 [149-343], p=0.001) allowing mechanical revascularisation within 90 minutes from the first medical contact in the vast majority of the patients (>80%). Clinically, pre-hospital triage showed no significant reductions in terms of adjusted long-term mortality (HR 0.81, 95% CI 0.61-1.08; p=0.16) in the overall population. However, significant adjusted survival benefits were observed in high-risk groups (i.e., cardiogenic shock, TIMI risk score >30, diabetes mellitus). Conclusions: This study shows that pre-hospital diagnosis allows for significant reductions in primary PCI treatment delays and suggests the hypothesis that this referral strategy might provide long-term survival benefits especially in high-risk patients