Evaluation Of Liner Back-pressure Due To Concrete Pore Pressure At Elevated Temperatures

Conference · Sat Jul 01 04:00:00 EDT 2006

OSTI ID:21021162

James, R J; Rashid, Y R ^[1]; Liu, A S; Gou, B ^[2]

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1. ANATECH Corp. G. E. Energy, San Diego, CA (United States)
2. G.E. Energy, San Jose, CA (United States)

GE's latest evolution of the boiling water reactor, the ESBWR, has innovative passive design features that reduce the number and complexity of active systems, which in turn provide economic advantages while also increasing safety. These passive systems used for emergency cooling also mean that the primary containment system will experience elevated temperatures with longer durations than conventional plants in the event of design basis accidents. During a Loss of Coolant Accident (LOCA), the drywell in the primary containment structure for the ESBWR will be exposed to saturated steam conditions for up to 72 hours following the accident. A containment spray system may be activated that sprays the drywell area with water to condense the steam as part of the recovery operations. The liner back-pressure will build up gradually over the 72 hours as the concrete temperatures increase, and a sudden cool down could cause excessive differential pressure on the liner to develop. For this analysis, it is assumed that the containment spray is activated at the end of the 72-hour period. A back-pressure, acting between the liner and the concrete wall of the containment, can occur as a result of elevated temperatures in the concrete causing steam and saturated vapor pressures to develop from the free water remaining in the pores of the concrete. Additional pore pressure also develops under the elevated temperatures from the non-condensable gases trapped in the concrete pores during the concrete curing process. Any buildup of this pore pressure next to the liner, in excess of the drywell internal pressure, will act to push the liner away from the concrete with a potential for tearing at the liner anchorages. This paper describes the methods and analyses used to quantify this liner back-pressure so that appropriate measures are included in the design of the liner and anchorage system. A pore pressure model is developed that calculates the pressure distribution across the concrete wall considering the time-dependent temperature distribution that evolves following the LOCA. The pressure distribution at each time increment is balanced for mass diffusion using Darcy's Law for mass flux under a pressure gradient. The total mass for the free water, the water vapor, and the non-condensable gases in the pore volumes is tracked to maintain conservation of mass. The evolution of liner back-pressure with time is then based on detailed finite element modeling that incorporates the pore pressure model into a concrete cracking analysis with full coupling between the temperatures, pressures, and liner displacements. (authors)

• Research Organization: American Nuclear Society, 555 North Kensington Avenue, La Grange Park, IL 60526 (United States)
• OSTI ID: 21021162
• Country of Publication: United States
• Language: English

Related Subjects

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS
BWR TYPE REACTORS
CONCRETES
CONTAINMENT SPRAY SYSTEMS
DESIGN
DESIGN BASIS ACCIDENTS
DISTRIBUTION
FINITE ELEMENT METHOD
LINERS
LOSS OF COOLANT
PORE PRESSURE
STEAM
TIME DEPENDENCE
VAPOR PRESSURE
WATER
WATER VAPOR