Study: Increased—but still small—radiation levels in water around San Onofre nuclear power plant

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A test to measure the amount of radioactive isotopes in beach water near the San Onofre nuclear power plant showed higher levels than are currently found along the California coast, but at concentrations well below legal drinking water limits.

The Surfrider Foundationan environmental group based in San Clemente, funded the study and collected samples that were tested by the Woods Hole Oceanographic Institute in Massachusetts, looking to see if the “batch releases” of wastewater coming out of the plant have resulted in a measurable increase in cesium-134 and 137 isotope levels in the ocean.

The readings for cesium-134 were so low that the concentration could not be detected.

As for cesium-137, samples returned to a level nearly double what is considered the “ambient ocean concentration level” for Californian waters, even after monitoring the effects of the Fukushima nuclear disaster. in 2011 on the state coast. That said, even a doubling is a tiny fraction of the national regulatory limit for cesium-137 in drinking water.

“I was thrilled to see that the levels of this specific isotope were so low in the beach water, especially compared to what the EPA legally allows to have in drinking water,” said Katie Day, Head of Environmental Science and Policy for Surfrider.

In scientific terms, the ambient oceanic concentration of isotopes in California ocean waters is 2 Becquerels per cubic meter, or 2 Bq/m3, after Fukushima.

Water samples taken around San Onofre in April this year and February 2021 had readings between 2.9 Bq/m3 and 3.9 Bq/m3. As a reminder, the drinking water limit set by the United States Environmental Protection Agency is 7,400 Bq/m3.

As seen at other nuclear power plants located next to large bodies of water, batch discharges of liquid effluent are permitted under licensing requirements at the San Onofre Nuclear Power Plant, known as SONGS for short. Traveling through long conduits, radioactive waste water from SONGS is sent over a mile offshore and about 50 feet below the surface.

Wastewater must be cleaned and heavily diluted before being discharged into the ocean.

Surfrider, concerned about the potential effect of batch releases on the popular San Onofre State Park, wanted to perform its own independent and third-party testing of radiation water levels.

Visitors to San Onofre State Beach, with the San Onofre Nuclear Power Plant in the distance.

(Christopher Reynolds/Los Angeles Times)

The organization took water samples from the surf area and the discharge area where the sewage batches were discharged and sent them to the Our Radioactive Ocean program in Woods Hole. Surfrider published the conclusions earlier this week.

“Given the variations in tides and upwellings along the California coast, such small differences cannot be attributed to any local source,” Ken Buesselerprincipal researcher and founder of the Marine and Environmental Radioactivity Center in Woods Hole, said in the Surfrider report.

However, Surfrider wants to perform another test for two reasons. First, Southern California Edison, the operator of SONGS, plans to drain the pools that had been used to cool the radioactive fuel rods when the plant was still operating. Batch releases from swimming pools may likely have higher levels of radiation.

“SONGS will need to heavily treat and filter the cooling pool water before releasing it,” Surfrider’s Day said in an email, “but we believe additional eyes testing the effect on radiation levels of the water from the beach wouldn’t hurt.”

Additionally, baseline samples for the study taken in February 2021 had higher cesium-137 levels than measurements taken immediately after the release of this year’s batches in April. Surfrider therefore wants to perform another test to find out more clearly whether the discharges lead to higher concentrations of the isotope in the beach water.

Day estimated the study cost $3,300. Donations from the public helped defray the expenses.

“We were delighted to be able to work with Surfrider to provide information so they could collate their samples, which reinforces that SONGS is contributing little to the radiological environment that exists around us,” the spokesperson said. of Edison, John Dobken.

The utility said SONGS collects seawater samples every month which are analyzed by an independent laboratory. “We also test, at various intervals, ocean floor sediments, shoreline sediments (beach sand) and marine life,” Dobken said.

SONGS started operations in 1968 but the plant has not produced electricity since 2012, after a leak in a steam generator tube caused its closure. The plant is being decommissioned and is currently in the third year of a planned eight-year, $4.5 billion decommissioning project that has so far seen $128.4 million pounds of materials shipped off the 84-acre site.

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