原因と対策2002� ��4月10日11時00� �.pdf

Four incidents occurred at the Ikata Nuclear Power Plant:
1. a leak from the condensate flow measurement pipe valve (Unit 1) on December 26, 2001,
2. an air leak from the minimum flow valve drive air pipe (Unit 2) on February 4, 2002,
3. damage to the heat transfer tube of the low-pressure feedwater heater (Unit 1) on February 14, 2002, and
4. automatic shutdown of the ethanolamine treatment device (common to Units 1, 2, and 3) on February 22, 2002.
The causes and countermeasures for these incidents are being reported.
The leak from the condensate flow measurement pipe valve was likely due to stress corrosion cracking caused by seawater particles.
The air leak from the minimum flow valve drive air pipe was likely due to fatigue failure caused by vibration.
The damage to the heat transfer tube was likely due to stress corrosion cracking caused by a dent during manufacturing.
The automatic shutdown of the ethanolamine treatment device was likely due to a decrease in the thickness of the electrode plate coating, causing an increase in voltage.
Countermeasures include replacing the affected parts, inspecting and maintaining the equipment, and implementing measures to prevent similar incidents in the future.