classification of loss of coolant accidents in pressurised water reactor

Introduction

Loss of Coolant Accidents (LOCAs) in pressurized water reactors (PWRs) are critical events where the integrity of the reactor's coolant system is compromised, leading to potential safety hazards. Understanding the classification and behavior of LOCAs is essential for improving reactor safety and mitigating risks.

Key Insights

Pressure Drop and Phase Transitions:
- In traditional PWRs, a pressure drop during a LOCA can lead to flash boiling, which is a rapid phase transition from liquid to steam.
- In Supercritical-Water Cooled reactors, the pressure drop can either cause a fast phase transition (flash boiling or steam collapse) leading to a pressure surge, or it can smoothly transition to the dry steam region.
Modelling of LOCAs:
- LOCAs can be modeled as isentropic (constant entropy) and isenthalpic (constant enthalpy) processes to predict outcomes based on initial pressures and temperatures.

Conclusion

LOCAs in PWRs involve complex interactions between pressure drops and phase transitions, which can be modeled to predict various outcomes. Understanding these dynamics is crucial for enhancing reactor safety and preventing catastrophic failures.

Classification of loss of coolant accidents in pressurised water reactor

Summary

Introduction

Key Insights

Conclusion

Sources and full results

Physical-chemical Background of the Potential Phase Transitions during Loss of Coolant Accidents in the Supercritical Water Loops of Various Generation IV Nuclear Reactor Types

Supercritical-water-cooled nuclear reactors can experience loss of coolant accidents, with potential phase transitions and pressure surges, and can be analyzed using only physical-chemical properties of the supercritical fluid.

Cold pressurisation in pressurised heavy water reactors during accidents

Cold pressurisation in pressurised heavy water reactors during accidents, such as non-LOCA events and steam line breaks, must be avoided to prevent consequential failures.

Long-term recovery of pressurized water reactors following a large break loss-of-coolant accident☆

Long-term cooling of pressurized water reactors following a large break loss-of-coolant accident may not be ensured, but boiling and condensation-induced flow oscillations are sufficient to prevent fuel rod heatup.

Analysis of Severe Accident Induced by Loss of Coolant Accident for a Small Pressurized Water Reactor

Small pressurized water reactors experience faster pressure recovery after a loss of coolant accident, requiring specific safety measures to prevent core melt.

Loss-of-Coolant Accidents in Small Compact Nuclear Reactors

A loss-of-coolant accident in a consolidated nuclear steam system (CNSS) may be less severe than in typical loop-type pressurized water and boiling water reactors due to smaller piping connections.

Heat transfer during a small-break loss-of-coolant accident in a pressurized water reactor—A parametric study for a 4 in. Lower-plenum break

The predictions of loss-of-coolant accidents in pressurized water reactors are significantly affected by the number of grid nodes, heat-transfer representations, and stratified two-phase flow modeling in horizontal pipes.

Evaluation of chemical effects on fuel assembly blockage following a loss of coolant accident in nuclear power plants

AlOOH precipitates in nuclear power plants can increase pressure drop across the fibrous bed, potentially hindering decay heat transfer and causing blockage after a loss of coolant accident.

Cladding tube deformation and core emergency cooling in a loss of coolant accident of a pressurized water reactor

In a loss-of-coolant accident, core coolability and public safety are not impaired due to cladding tube deformation or cooling channel blockage, as the two-phase mixture cooling effect and fuel rod bundle unidirectional flow ensure safety.

Accident management following loss-of-coolant accidents during cooldown in a Westinghouse two-loop PWR

The study confirms the inherent robustness of the Westinghouse PWR design against loss-of-coolant accidents during cooldown to cold shutdown, and validates a two-tier calculational method for assessing core cooling success.

The Loss-of-Coolant Accident Analysis in Pressurized Water Reactors

This study presents a generalized digital computer approach for analyzing loss-of-coolant accidents in pressurized water reactors, addressing numerical stability and convergence issues.

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