graduate and undergraduate students set up sample monitoring stations (which were
later upgraded with more sophisticated instrumentation) to collect rain water and air
samples on the roof of Etcheverry Hall on the UC Berkeley campus. Subsequently,
other environmental as well as a wide range of local food samples were measured
utilizing state-of-the are radiation detection equipment available at UC Berkeley
and LBNL. The goal of this activity was two-fold: (1) To study the characteristics,
such as type and quantity, to determine whether measurable amounts of radioactive
materials that we could associate with the releases in Fukushima could be detected
(including monitoring for the gradual disappearance of measurable materials);
(2) To make the results from the monitoring stations easily accessible and digestible
to the general public and to engage the public in a dialogue about radiation and to
put our findings in the context of the radiation we are exposed to naturally or
electively on a daily basis.
The effort described above, as well as ongoing measurements conducted at UC
Berkeley, are part of the Berkeley RadWatch project [15]. Within one week of the
2011 accident in Fukushima, we established a website, which hosted results and
analysis, as well as a forum for discussion of the results. Responses to claims and
results from other sources, in some cases, claims that were scientifically inaccurate
or did not have any scientific basis, were also posted on the site. Since the start of
this program in 2011, we have performed more than 1000 measurements with all
data and results available at the website. Early in 2014, our team installed an
automatic and near-real-time air monitor that provides activities of radioactive
particulates captured in a filter mounted in front of a high-energy resolution
high-purity gamma-ray spectrometer. This system represents a world-wide unique
instrument as it continuously measures radioactivity in air with a state-of-the art and
expensive gamma-ray spectrometer and provides the raw spectra and isotopic
analysis every 15 min.
In parallel with the RadWatch project, we established the Kelpwatch project
in collaboration with Steve Manley from California State University in Long Beach,
CA [16]. The goal of this activity was to measure radioisotopes in marine kelp that
is collected along the Pacific Coast of North America. Just as RadWatch monitored
the arrival of radioisotopes from Japan in California via the jet stream within about
70 h after the releases, the main goal of Kelpwatch was to observe the arrival of
radioactive materials that were released into the ocean in March 2011 and carried by
the Pacific Ocean currents to the coast of California. Oceanographic transport
models expected the appearance 2–4 years after the releases [17]. Kelp samples
were acquired and analyzed during five collection periods at about 40 sites between
February 2013 and May 2016. We were not able to measure Cs-134 in any sample.
The Cs-134 radioisotopes can be used as strong evidence to originate from the
Dai-ichi Nuclear Power Plant accident. This is in contrast to the observed Cs-137,
which also originated from Fukushima but also from the above-ground weapons
tests and has not disappeared yet due its 30 year half live. It is interesting to note
that the Cs-137 concentration we observed in kelp was in the order of 0.2 Bq/kg for
all samples and the limits for Cs-134 were 0.05 Bg/kg, indicating that most of the
Cs-137 observed remains from the weapons test more than 50 years ago. Since
212
K. Vetter
later upgraded with more sophisticated instrumentation) to collect rain water and air
samples on the roof of Etcheverry Hall on the UC Berkeley campus. Subsequently,
other environmental as well as a wide range of local food samples were measured
utilizing state-of-the are radiation detection equipment available at UC Berkeley
and LBNL. The goal of this activity was two-fold: (1) To study the characteristics,
such as type and quantity, to determine whether measurable amounts of radioactive
materials that we could associate with the releases in Fukushima could be detected
(including monitoring for the gradual disappearance of measurable materials);
(2) To make the results from the monitoring stations easily accessible and digestible
to the general public and to engage the public in a dialogue about radiation and to
put our findings in the context of the radiation we are exposed to naturally or
electively on a daily basis.
The effort described above, as well as ongoing measurements conducted at UC
Berkeley, are part of the Berkeley RadWatch project [15]. Within one week of the
2011 accident in Fukushima, we established a website, which hosted results and
analysis, as well as a forum for discussion of the results. Responses to claims and
results from other sources, in some cases, claims that were scientifically inaccurate
or did not have any scientific basis, were also posted on the site. Since the start of
this program in 2011, we have performed more than 1000 measurements with all
data and results available at the website. Early in 2014, our team installed an
automatic and near-real-time air monitor that provides activities of radioactive
particulates captured in a filter mounted in front of a high-energy resolution
high-purity gamma-ray spectrometer. This system represents a world-wide unique
instrument as it continuously measures radioactivity in air with a state-of-the art and
expensive gamma-ray spectrometer and provides the raw spectra and isotopic
analysis every 15 min.
In parallel with the RadWatch project, we established the Kelpwatch project
in collaboration with Steve Manley from California State University in Long Beach,
CA [16]. The goal of this activity was to measure radioisotopes in marine kelp that
is collected along the Pacific Coast of North America. Just as RadWatch monitored
the arrival of radioisotopes from Japan in California via the jet stream within about
70 h after the releases, the main goal of Kelpwatch was to observe the arrival of
radioactive materials that were released into the ocean in March 2011 and carried by
the Pacific Ocean currents to the coast of California. Oceanographic transport
models expected the appearance 2–4 years after the releases [17]. Kelp samples
were acquired and analyzed during five collection periods at about 40 sites between
February 2013 and May 2016. We were not able to measure Cs-134 in any sample.
The Cs-134 radioisotopes can be used as strong evidence to originate from the
Dai-ichi Nuclear Power Plant accident. This is in contrast to the observed Cs-137,
which also originated from Fukushima but also from the above-ground weapons
tests and has not disappeared yet due its 30 year half live. It is interesting to note
that the Cs-137 concentration we observed in kelp was in the order of 0.2 Bq/kg for
all samples and the limits for Cs-134 were 0.05 Bg/kg, indicating that most of the
Cs-137 observed remains from the weapons test more than 50 years ago. Since
212
K. Vetter