Nuclear Power Plant Maintenance Optimization with Heuristic Algorithm

Table 3

Unavailability and importance measures for selected basic events of the AFW system.

Rank FV	Basic event	Description	Unavailability	FV	RRW	RAW
1	AFW-CCF-FS-FW3AB	CCF of MDPFW3A & MDPFW3B	3.50𝐸−04	3.79𝐸−01	1.61𝐸+00	1.08𝐸+03
2	AFW-TDP-FS-FW2	TDPFW2 fails to start	1.10𝐸−02	3.37𝐸−01	1.51𝐸+00	3.13𝐸+01
3	AFW-TDP-FR-2P6HR	TDPFW2 fails to run 6 hrs	3.00𝐸−02	2.80𝐸−01	1.38𝐸+00	9.97𝐸+00
4	AFW-CKV-OO-CV142	Backflow through CV142	1.00𝐸−03	2.34𝐸−01	1.31𝐸+00	2.35𝐸+02
5	AFW-MDP-FS-FW3A	MDPFW3A fails to start	6.30𝐸−03	1.98𝐸−01	1.25𝐸+00	3.23𝐸+01
6	AFW-MDP-FS-FW3B	MDPFW3B fails to start	6.30𝐸−03	1.98𝐸−01	1.25𝐸+00	3.23𝐸+01
7	AFW-CKV-OO-CV172	Backflow through CV172	1.00𝐸−03	1.34𝐸−01	1.16𝐸+00	1.35𝐸+02
8	AFW-CKV-OO-CV157	Backflow through CV157	1.00𝐸−03	1.34𝐸−01	1.16𝐸+00	1.35𝐸+02
9	AFW-TDP-MA-FW2	Test and maintenance of TDPFW2	1.00𝐸−02	9.34𝐸−02	1.10𝐸+00	9.97𝐸+00
10	AFW-TNK-VF-CST	Insufficient water available from condensate storage tank	1.00𝐸−06	2.13𝐸−02	1.02𝐸+00	2.13𝐸+04
13	AFW-MDP-FR-3A6HR	MDPFW3A fails to run 6 hrs	1.80𝐸−04	1.84𝐸−03	1.00𝐸+00	1.12𝐸+01
14	AFW-MDP-FR-3B6HR	MDPFW3B fails to run 6 hrs	1.80𝐸−04	1.84𝐸−03	1.00𝐸+00	1.12𝐸+01
19	ACP-BAC-ST-4KV1H	4160 V AC bus 1H buswork failure	9.00𝐸−05	9.19𝐸−04	1.00𝐸+00	1.12𝐸+01
20	ACP-BAC-ST-4KV1J	4160 V AC bus 1J buswork failure	9.00𝐸−05	9.17𝐸−04	1.00𝐸+00	1.12𝐸+01
21	DCP-BDC-ST-BUS1A	125 V DC bus 1A buswork failure	9.00𝐸−05	9.19𝐸−04	1.00𝐸+00	1.12𝐸+01
22	DCP-BDC-ST-BUS1B	125 V DC bus 1B buswork failure	9.00𝐸−05	9.17𝐸−04	1.00𝐸+00	1.12𝐸+01