Key Facts
• July 21: Cooling system in shared spent fuel pool stopped due to fan malfunction.
• Pool temperature at 8:00 PM was 33.3°C, with 6,188 spent fuel units stored.
• Critical temperature of 65°C expected in approximately 8 days without cooling.
• TEPCO is investigating the cause and working to restore the cooling system.
• 7:40 PM: Pumps supplying refrigerant to the “landside impermeable wall” also stopped.
• The wall prevents groundwater from entering reactor buildings and reduces contaminated water.
• TEPCO states the wall’s effectiveness will last for several months despite the issue.
• No significant changes in water levels or environmental impact have been observed.
• Severe weather, including lightning and tornado warnings, occurred near the plant on July 21.
• TEPCO manually halted treated water discharge into the ocean after 7:00 PM due to weather.
Summary
On July 21, Tokyo Electric Power Company (TEPCO) reported a cooling system failure in the shared spent fuel pool at the Fukushima Daiichi Nuclear Power Plant. The pool, containing 6,188 spent fuel units, reached 33.3°C, with an estimated 8 days before hitting the critical temperature of 65°C. TEPCO is investigating the issue and working to restore cooling. Additionally, pumps supplying refrigerant to the landside impermeable wall, designed to reduce contaminated water, also stopped. Despite this, the wall’s effectiveness is expected to last for months. Severe weather, including lightning and tornado warnings, prompted TEPCO to manually stop treated water discharge into the ocean. No significant environmental impact or water level changes have been reported.
