Global Warming Shuts Down LaSalle

Facility: LASALLE
Event Number: 46171
Event Date: 08/12/2010

TECHNICAL SPECIFICATION REQUIRED SHUTDOWN DUE TO ENVIRONMENTAL CONDITIONS RESULTING IN ELEVATED ULTIMATE HEAT SINK TEMPERATURE

"At 2050 [CDT] on 8/12/10, LaSalle Unit 1 and Unit 2 commenced a Plant Shutdown. At 1952 [CDT] on 8/12/10, LaSalle Ultimate Heat Sink exceeded the 101.25?F limit per Technical Specification LCO 3.7.3, Condition B. Per Technical Specification LCO 3.7.3, Required Action B.1, both Unit 1 and Unit 2 are to be in Mode 3 (Hot Shutdown) in 12 hours. Per Technical Specification LCO 3.7.3 Required Action B.2, both Unit 1 and Unit 2 are to be in Mode 4 (Cold Shutdown) in 36 hours. Technical Specification LCO 3.7.3, Ultimate Heat Sink requires that both Unit 1 and Unit 2 to be in MODE 3 by 8/13/10 at 0752 [CDT] and MODE 4 by 8/14/10 at 0752 [CDT].

"Unit 1 was initially at 76% Power due to a response to elevated Main Condenser In-Leakage, not related to the Ultimate Heat Sink High Temperature. Unit 2 was initially at 82% Power due to elevated Condensate Temperature and in response to worsening Main Condenser Backpressure. For Unit 2, both of these parameters were related to the elevated Ultimate Heat Sink Temperature.

"The Ultimate Heat Sink Temperature is currently 101.33?F. All Systems are responding as expected."

This condition is a result of the hot environmental conditions and is not due to any equipment problems or other operating issues at the site.

The licensee has notified the NRC Resident Inspector.