NULL
Empty 1
NULL
Empty 2

News

USA fleet member Prairie Island recently completed the construction of its FLEX Beyond Design Basis Building that houses the FLEX response equipment. The building’s robust design is due to withstand a missile generated from a design basis tornado. It also meets the site’s license design basis (USAR) for extreme high wind, airborne tornado missiles and seismic loading in accordance with Prairie Island Class 1 structures.

FLEX building facts:

· Outside building dimensions are 71′ wide x 176’ long x 24′ tall

· The FLEX building is supported on a 46″ thick mat foundation

· Walls and roof are composed of 3′ thick cast

· The building is designed to withstand 360 mph tornado wind loads and tornado driven missiles

· The building can withstand missiles such as a 4,000 lb. automobile traveling at 50 mph and a 150 lb. wood plank traveling at 300 mph

· It took approximately 470 trucks of concrete (4,700 cubic yards or 10,810 tons of concrete) to complete the entire structure

· The structure consists of approximately 1,500 tons of No. 9, 10 and 11 rebar (No. 11 rebar is 1 3/8”)

· Man hours works for the building construction is approximately 50,000 man hours.

Prairie Island also procured custom built FLEX portable pumps that will be used to provide core heat removal in the event that the installed steam driven Auxiliary Feedwater pump became unavailable. The pumps would provide water from the plant’s intake canal to feed the steam generators.

If a seismic event resulted in the failure of Lock and Dam failure just downstream of the plant, a second, submersible pump would be used to provide water to the steam generator injection pump. The steam generator pump is also capable of providing makeup water to the spent fuel pool in the event that normal cooling is lost to the pool. The steam generator injection pumps have a capability of 500 gallons per minute (GPM) at 500 pounds per square inch (psi), while the submersible pump has a complimenting capability of 500 GPM.

Prairie Island’s Unit 2 will be compliant with the FLEX orders set forth by the NRC in response to the Fukushima events upon completion of its refueling outage this fall. The orders remaining on Unit 1 will be completed during the refueling outage next fall.