North California radiation

CALIFORNIA BEACH RADIATION NOT FROM FUKUSHIMA

Geiger Counter,

5 January, 2014

A lot of concern has been expressed about recent reports and videos showing high levels of radiation on a beach in Half Moon Bay, just South of Pillar Point Harbor.  It has been attributed  to Fukushima.  Local officials have been quoted as saying they donʻt know what it is, but donʻt worry about it.  

See local story.

Here is what we have learned so far:   The radioactive areas of the beach seem to be associated with dark sand below the high tide level.   The levels detected are about 5 to 10 times what you would normally expect to find on a beach.

The radionuclides are in the NORM class of radioactive substances, not from Fukushima. NORM stands for Naturally Occurring Radioactive Material.   We put a sample in a Multichannel Analyzer and found Radium 226 and Thorium 232.  See the measured spectra below.

This is the spectra from the beach sample

If the sand were contaminated by radiation from Fukushima it would show Cesium 137. See spectra below from contaminated area of Fukushima Prefecture.  The same instrument is identifying Cesium 137 rather than Radium and Thorium.

Sample of deck material from contaminated area of Fukushima Prefecture

The picture below is a geiger counter measuring the activity in a sample bag of the sand. The radiation level is elevated, but roughly equivalent to some granite counter top material from Brazil.

This is a geiger counter with 2 inch pancake detector measuring the activity in the sand sample

Whether this material is naturally occurring at this beach or not remains a question. There are also reports that a pipeline was once at this location.  We hope the State will do further testing to determine the origin and full nature of the hot spots on the beach. But we are confident that it is not related to Fukushima, based on the spectral signature.  We expect more news later today.

From earlier

Health officials respond to beach radiation scare

Half Moon Bay Review,

3 January, 2014

An amateur video of a Geiger counter showing what appear to be high radiation levels at a Coastside beach has drawn the attention of local, state and federal public health officials. Since being posted last week, the short video has galvanized public concerns that radioactive material could be landing on the local coastline after traveling from Japan as a result of the 2011 meltdown of the Fukushima Daiichi reactors.

Government officials say they are looking into the video shot on Dec. 23 and performing their own sampling of the beaches, but they have found no indication so far that radiation levels were hazardous.

“It’s not something that we feel is an immediate public health concern,” said Dean Peterson, county environmental health director. “We’re not even close to the point of saying that any of this is from Fukushima.”

First posted last week on YouTube, the seven-minute video shows the meter of a Geiger counter as an off-camera man measures different spots on the beach south of Pillar Point Harbor. The gadget’s alarm begins ringing as its radiation reading ratchets up to about 150 counts per minute, or roughly five times the typical amount found in the environment.

Counts per minute is a standard way for Geiger counters to measure radiation, but it does not directly equate to the strength or its hazard level to humans. Those factors depend on the type of radioactive particles and isotope.

Nonetheless, the video went viral online, gaining nearly 400,000 views in the last week.

In a blog entry, the unidentified poster of the video noted that he has been monitoring local beaches for two years before noticing a sudden rise in radiation levels in recent days. The Review was not immediately able to contact the man who made the video.

In the following days, other amateurs with Geiger counters began posting similar videos online. The videos follow other alarming news last month that starfish were mysteriously disintegrating along the West Coast, a trend that has not been linked yet to any cause. Past computer simulations had indicated that radioactive cesium-137 from the Fukushima reactors could begin appearing on West Coast shores by early 2014. Those findings, published in August by the Institute for Cross-Disciplinary Physics and Complex Systems in Spain, also noted that any radioactive material that crossed the Pacific would likely be diluted and fall below international safety levels.

County health officials first learned of the radiation levels last week, and they sent their own inspector on Dec. 28 to Pacifica with a Geiger counter. Using a different unit, the county inspector measured the beach to have a radiation level of about 100 micro-REM per hour, or about five times the normal amount. REM stands for “Roentgen equivalent man,” a measurement of the dosage and statistical biological effects presented by radiation.

Although the radiation levels were clearly higher than is typical, Peterson emphasized that it was still not unsafe for humans. A person would need to be exposed to 100 microREMs of radiation for 50,000 hours before it surpassed safety guidelines by the Occupational Safety and Health Administration, he explained.

Peterson admitted he was “befuddled” as to why radiation levels were higher than normal, but he was skeptical that the Fukushima meltdown could be the cause. He noted that many innocuous items could spike the radiation levels in an area, including red-painted disposable eating utensils.

“I honestly think the end result of this is that it’s just higher levels of background radiation,” he said.

Peterson forwarded the matter to the U.S. Environmental Protection Agency and state Department of Public Health, agencies with more expertise on analyzing radioactivity.

A state Public Health spokeswoman said her office was contacted on Thursday and was still looking into the matter. More information would be available by next week, she said.

“We can’t comment on anybody’s media creation. We really have no way of knowing right now whether it’s valid or not,” said spokeswoman Wendy Hopkins.