Environmental Monitoring is Key to Safely Decommissioning SONGS

In our oversight role, Southern California Edison is committed to transparency in the decommissioning of the San Onofre nuclear plant and operates with a bias toward making the public aware of even low-level issues that do not affect health or safety but may be of interest.

To protect the environment around SONGS during the dismantlement of the facility’s structures, strict and timely monitoring programs are in place. In fact, these types of programs have been in place since before SONGS Unit 1 began operating in 1968.

Southern California Edison conducts year-round monitoring of:

  • Air
  • Ocean water
  • Ground water
  • Ocean bottom sediment
  • Soil
  • Vegetation
  • Marine animals and plants

It was during recent groundwater monitoring that we observed a slightly elevated level of tritium in one of the onsite groundwater monitoring wells at SONGS. In August, an adjacent well used for monitoring different, non-radiological parameters was also sampled to help us better understand the extent of the condition.


What is Tritium?

Tritium is produced naturally from the interactions of cosmic rays and gases in the upper atmosphere. A radioactive form of hydrogen, tritium also is a by-product of nuclear reactors. Tritium is present in groundwater and surface waters everywhere to varying degrees.

The tritium concentration in the groundwater well is 3,430 picocuries per liter, and the finding in the second adjacent well is 19,100 picocuries per liter.

Those may sound like big numbers, but for perspective, these tritium levels are below the standard for our drinking water (20,000 picocuries per liter) – a point we make to underscore the absence of a health hazard. Groundwater at SONGS and the general region around us is not designated as a source of drinking water by the Regional Water Quality Control Board’s San Diego Basin Plan. SONGS groundwater quality has been monitored for decades to ensure timely detection of tritium or other radionuclides and to ensure that there are no offsite effects.

What You Should Know

There continues to be no indication of adverse effects on health or the environment from SONGS groundwater. For the past 50 years, as part of the plant operating license, SCE has produced annual Radiological Environmental Monitoring Program (REMP) reports, as required by the Nuclear Regulatory Commission (NRC). This report summarizes the detailed findings of any radioactivity in the environment surrounding SONGS, including ocean water, sediment, and beach sand. The annual Radioactive Effluent Release Report specifically tracks tritium levels. These reports are available to the public and can be found on our SONGS website. According to the SONGS operating license, the allowable limit for tritium in a REMP ocean water sample that prompts reporting is 30,000 picocuries per liter. Our findings remain well below this level.

The SCE Environmental team will continue monitoring the situation while developing potential actions to remediate the condition.

Has SONGS reported tritium releases before?

Yes. During the Unit 1 Decommissioning project in 2006, traces of tritium from below the Unit 1 containment area was also detected and subsequently remediated during the decommissioning of the Unit 1 site. As seen in the annual environmental reports, very low amounts of tritium are found in water that’s released as part of routine plant operations and are below limits set to protect the health and safety of the public.

Is this tritium issue related to the spent fuel and the storage pad?

No. The spent fuel is a solid ceramic material and isolated from the environment in robust stainless-steel canisters on the dry storage pad. These tritium samples are from wells in a different location.

What are your next steps?

SCE has retained an independent hydrogeologist to assess the area and develop recommendations for remediation. We are also sampling additional wells to better understand the extent of condition.

What is the source?

We believe it is a result of decommissioning activity; however, we will know more once the hydrogeologist completes their investigation.

Will SCE follow-up with more information about this tritium detection at the next Community Engagement Panel meeting?

Yes. We will provide an update at the next CEP meeting on November 7. We will also update this blog post with new information when it is available.