Effect of primary feed-and-bleed on core melt frequency

Conference · Thu Jan 01 04:00:00 EST 1987 · Trans. Am. Nucl. Soc.; (United States)

OSTI ID:5746162

Summitt, R L

This paper presents the effects produced on pressurized water reactor (PWR) core melt frequency by the inclusion of primary feed-and-bleed as a decay heat removal mechanism. An analysis is performed for a standard PWR design in which the dominant accident sequences taken from probabilistic risk assessments (PRAs) are developed with and without primary feed-and-bleed. The change in core melt frequency is discussed along with the main contributors to core melt and how primary feed-and-bleed affects them. The reduction in core melt frequency is then compared to the reductions possible from changes in the emergency feedwater system. This includes the addition of redundant and diverse pumps to the emergency feedwater system. The use of an additional diverse and/or redundant train of feedwater provides for greater reduction in core damage frequency for the dominant sequences than primary feed-and-bleed. This is due to the dependent on similar support systems for both the ECCS and motor-driven emergency feedwater pumps. This link results in failure of emergency feedwater and consequential failure of primary feed-and-bleed for many of the dominant accident sequences, such as station blackout. This conclusion is important for advanced light water reactors that are being developed. Consideration should be given to the addition of a turbine-driven or other diverse pump for emergency feedwater for advanced plants.

• OSTI ID: 5746162
• Report Number(s): CONF-870601-
• Conference Information: Journal Name: Trans. Am. Nucl. Soc.; (United States) Journal Volume: 54
• Country of Publication: United States
• Language: English

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