Investigation of Loss of Feedwater (LOFW) Accident in the APR-1400 Using Fault Tree Analysis

Table 1

Component unreliability of the main feedwater system.

Basic event	Component code	NUREG-6928 /IAEA-478	WASH-1400
		Mean	Mean
Check valve fails to open	A, AI, AH, F, K, P	1.30E − 05/d	1.00E − 04/d
Control valve fails to open	AE	2.50E − 02/d	1.00E − 03/d
HP feedwater heater failure	AA, AB, T, V, W, Y	1.30E − 05/h	7.10E − 04/h
Hydraulically operated MFIV fails to open	AF, AG	1.51E − 03/d	3.00E − 04/d
Large leak from the deaerator storage tank	B	2.75E − 09/h	1.00E − 10/h
Motor-driven booster pump fails to run	D, I, N	4.54E − 06/h	3.00E − 05/h
Motor-driven bypass line isolation valve fails to open	AD	1.07E − 03/d	1.00E − 03/d
Motor-driven inlet isolation valve fails to open	U, Z	1.07E − 03/d	1.00E − 03/d
Motor-driven outlet isolation valve fails to open	AC, X	1.07E − 03/d	1.00E − 03/d
Motor-driven startup pump fails to start	S	2.23E − 03/d	1.00E − 03/d
Pipe rupture >3″ in diameter	AJ	1.00E − 10/h	1.00E − 10/h
Total loss of offsite power	C	4.10E − 06/h	1.00E − 05/d
Turbine-driven main feedwater pump fails to run	E, J, O	5.77E − 06/h	3.00E − 05/h