New Membrane Liner Protects Water at Nuclear Power Plant

Recognized as one of the top U.S. nuclear power facilities, the Diablo Canyon Nuclear Power Plant offers a major source of safe, clean energy that helps ensure reliable electric service to more than two million Californians every day. Lying along the Pacific Coast near San Luis Obispo, CA, about 200 miles north of Los Angeles, the Diablo Canyon plant combines magnificent man-made architecture with the natural beauty of the region.

One of its most outstanding features is the 4.5 million gallon fire retention water reservoir located adjacent to the power plant. The reservoir consists of two smaller connecting reservoirs and holds chemically treated water for use at Diablo Canyon.

Recently, the reservoir's PVC lining, which was in place since 1984, started failing. Colorado Lining International (CLI), of Parker, CO, was recruited for the job and made the decision to use Carlisle SynTec's white 60-mil Reinforced Polypropylene (RPP) GeoMembrane™.

"We chose this membrane because of its extreme durability and its 'lay flat' characteristics," said Bryant Jefferson, plant manager and estimator for CLI. "This was our first major project using [it], but we were familiar with the company's 40-year reputation as a manufacturer of single-ply roofing membranes."

The RPP membranes utilize the same puncture resistant and heat seaming technology integrated into thousands of commercial roofs across the country. They're designed to withstand harsh elements including heat, wind, snow and ice, and are reinforced with polyester fabric scrim to provide dimensional stability and toughness.

Once the reservoir was prepped, installation of the custom fitted sheets began. As Jefferson explained, this was not a routine fit.

"The reservoirs were oddly shaped. There were two pre-existing depressions divided by a center berm," he said. "There were very few straight edges, which created the need for complicated measurements. It wasn't a standard installation."

But the RPP membrane simplified the process, he said.

"It was delivered in 12-foot widths, which made it quick and easy to cover a lot of the straight runs. At the same time, we were able to easily manipulate the heavy-duty liner giving us the flexibility we needed for the custom cuts. The material worked out really well. The membrane's 'lay flat' characteristics are important in preventing algae growth, too. We've experience in the past that membranes without a smooth surface will collect the blue-green algae," he said.

Two methods – heat welding-fusion welding and hot air welding – were used to install the membrane. After the membrane was in place, a chlorination system was installed to keep the water and membrane clean.

Jefferson was sad to see the job end. "Driving along the coast every day to arrive at a job site that's considered one of the most beautiful places on the West Coast was certainly a treat." With the previous liner 20 years old, he added, "It doesn't look like we'll be back to Diablo Canyon any time soon."

For more information on the RPP GeoMembrane, Carlisle SynTec – based in Carlisle, PA – can be contacted at 800-479-6832 or [email protected].