...And A Deceptively False Release Model
On April 30 of this year the California Coastal Commission released a report entitled The Fukushima Dai-ichi Nuclear Power Plant Disaster & Radioactivity in California. In that report the Commission concluded that as the plume of radioactivity reaches the California coast, concentrations of cesium will likely peak between 2016 and 2019, and decline gradually over "several decades" after that due to decay of the shorter-lived cesium-134. It made no predictions about strontium or other radionuclides other than to dismiss them as insignificant.
In terms of potential impacts on marine life along the coast of California - from cesium alone - the report states -
When the plume of radioactivity currently spreading across the North Pacific reaches the California coast, local marine life will accumulate Fukushima-derived radioactive cesium (and other radionuclides present at much lower levels, such as 90sr).
While the levels are considered to be "unlikely to accumulate dangerous quantities of radioactivity," the Commission states that ongoing monitoring is "clearly warranted." Unfortunately, neither the federal government nor the state of California are currently testing for Fukushima radiation off the California coast. Instead, volunteers among the general public and a consortium of academic institutions are doing some occasional monitoring.
The devil's in the details, as usual. The Commission relied upon early estimates of total waterborne releases that themselves relied upon TEPCO's reported figures, long found to be consistently and suspiciously low (if and when reported at all). Worse, they further relied upon a model source and source term for those releases that suffers from a conspicuous lack of knowledge of the actual physical engineering of the reactor plants that melted, exploded and burned at Daiichi.
That erroneous model (a version published in the journal Biogeosciences 26 September, 2013, for those interested), has managed to provide a false narrative for waterborne releases from Daiichi to just about every ocean sciences research group and/or 'official' body that has attempted to quantify the level of ocean contamination coming from the facility since Day-1 of the disaster.
While no one can fairly expect academic scientists to understand the technical details of nuclear power plant design and operation, it wouldn't hurt any of them to do a bit of basic background research to familiarize themselves, especially when fed pat story lines by invested nuclear operatives. If for no other reason than to ensure that what they've been told is something close to plausible. In the matter of radioactive pollution of the Pacific from Fukushima, it does not appear that any of them bothered.
That's a shame, because false information can and does lead to false models, and in a matter such as this the falsehoods can do real harm. Sort of like the outrageous new EPA intervention levels [Protective Action Guidelines - PAGs] for allowable concentration of radionuclides in food and water, which reach the equivalent of 3 chest x-rays a day for the rest of one's life, as is the radiation-caused lifetime cancer rate of 1:1.7 (higher for women and children) in the exposed population. Or, as put in the wording of the regulations, no more than 2 additional cancer deaths per year per 10,000 people. In a post-accident/disaster environment, it's apparently okay to have a ~2 in 3 lifetime cancer rate in populations too brainwashed to get the hell outta there despite the standard "No [Immediate] Danger To The General Public" assurances.
Consider the EPA restrictions on releases of cancer-causing substances to the environment from chemical plants. Which restrict levels to "no more than one [1] additional cancer per 100,000 over a lifetime [70 years]." And that's incidence, not fatality. Union Carbide and Monsanto have to abide by the lower limit, while just one [1] of Exelon's nukes gets to kill 20 people a year at the on that scale. Worse, such levels of contamination no longer require any cleanup (decontamination).
Of course, such extrapolations from statistical indeterminism don't mean much when talking about a disease that takes years to manifest and for which actual determination of cause is vanishingly rare. Polluters of any variety can - and will - always deny that any individual's cancer was caused by their dumped wastes, and there is no reliable way to trace specific exposures as cause of later cancers.
At any rate, the bioaccumulated level of Fuku-derived radionuclides in seafood off California will most likely never reach the level of 1,200 Bq/kg [EPA, 12 times the allowable level in Japan]. It's not like anyone could actually do anything to stop the radionuclides from getting out, or bioaccumulating in food chains on land or in water. Best to set your actionable limits much higher than you expect they'll ever go, then not bother to tell the public how high the levels actually are. Cost-Benefit. We are all familiar with that...
"This is a public health policy only Dr. Strangelove could embrace," stated Jeff Ruch, director of Public Employees for Environmental Responsibility, noting that the EPA PAG lacks an understandable rationale."
Though post-Fukushima, the rationale isn't really so obscure.
In the meantime, the waterborne release model described in the Biogeosciences publication - and which other ocean sciences are apparently using - locates the direct waterborne releases (those not from atmospheric fallout or leakage over the cliff barrier of rainwater runoff, trench dribbling and occasional storage tank blow-outs) to be coming from the seawater discharge outlets for what is described as "the reactor plant cooling water."
These direct releases in the first weeks, we are told, were 10,000 to 100,000 times higher than the ever-increasing direct water releases that have been coming out by the hundreds of tons per day ever since. As a means to discount those constant and increasingly radioactive releases as meaningful in terms of ocean contamination and food chain bioaccumulation.
The problem with that model pathway is that the reactor plants at Fukushima Daiichi do NOT use seawater as reactor plant coolant. Seawater is used to cool the condenser system (piped refrigerant coils around the outside of post-turbine primary piping leg). These condense the steam back into water for the reactor. The pipes then pass through seawater to shed excess heat before cycling back for the compression/decompression cold-coil cycle to condense more steam). These seawater post-condenser cooling loops have NO piping connections to the primary coolant system at any point. The primary exclusively uses demineralized (basically distilled) water. In normal operation, they don't even add boron to it.
Hence this scenario - convincing as it may be to people who know nothing about the engineering of GE Mark I-III BWRs - cannot provide an explanation for supposedly 'huge' direct ocean releases coming from Daiichi's destroyed reactor plants in the first days and weeks of the disaster. Bottom line: The ocean pollution has to come from some other pathway, and such pathway was NOT open in the first weeks of the disaster, before the corium melted its way into the basements and 'became one with' the exterior environment.
TEPCO's long history of deception, falsification and withholding of data - from years before the Daiichi disaster as well as ever since - does not make them a trustworthy source. The various divisions of the Japanese government established to promote more than regulate the nuclear industry have also proven themselves untrustworthy. So untrustworthy, in fact, that the regulatory division in charge when the disaster happened had to be disbanded last year and replaced with a 'new and improved' agency.
At any rate, the model that asserts 'huge' direct to ocean releases of corium contaminated reactor coolant via the post-condenser seawater loop early on in the disaster [March-April 2011] is false on its face unless TEPCO and the world industry are willing to admit the earthquake (NOT the tsunami) so completely trashed the turbine building piping in these plants that all systems (including chemical refrigerant in the condenser coils) poured out as one, from the post-condenser heat exchange loop. And even then there would have to have been some liquid in the primaries, which there wasn't.
When it was decided to supply seawater to the reactors because there was no fresh water coolant available due to three simultaneous LOCAs/EDG failure [LOCA - Loss of Coolant via broken pipes/fittings and no backup or circulation pumps], heavy duty fire hoses were used to pump seawater from the lagoon via fire engine and later external pumps into primary system piping taps exterior to the reactor buildings. Unfortunately, in-line check valves upstream of where the taps were located prevented most of that seawater from reaching the reactors. Instead, it back-flowed into the turbine building basements, and from there leaked into the trenches and over the cliff wall into the lagoon.
Once fresh water was restored, it still didn't reach the vessels or cores. The water shunted to the turbine building basements was certainly radioactive, as was/is everything at Daiichi, but it had not come into contact with the reactors or their cores that had been busily melting through the reactor vessels into the containments below and from there into the suppression pools and lower level basements. Where it came into contact with groundwater flowing through the cracked basement walls and pipe fittings on its way out to sea, exiting the facility from groundwater sinks well outside the artificial lagoon. TEPCO and NRA recently admitted it took 6 months before the check valves were opened and coolant water reached the reactor vessels. By which time they were bottomless, their used-to-be cores elsewhere entirely. They called that "Cold Shutdown."
Indirect releases of core materials and fission products via fallout from aerial plumes in the first weeks were definitely thousands of times higher in the first weeks than since, as the xenon-133 and iodine-131 and cesium-134 decayed rather rapidly. Leaving the medium range half-life isotopes to be concerned about - cobalt-60, krypton-85, tritium, cesium-137, strontium-90, iodine-129, etc. But the tale of 'huge' direct-to-ocean waterborne releases from Daiichi's melting/melted reactors in the first weeks of the disaster is, in short, fatally flawed due to reliance on a pathway that never existed. All official reliance upon that false cover story is to support the pretense that direct waterborne releases were somehow tens of thousands of times higher in the first weeks than all the increasingly radioactive waterborne releases that have gone out daily ever since.
The airborne releases - and subsequent fallout to the ocean - were definitely worst in the first weeks, and contributed the greatest amount of nuclear contamination to the ocean from Daiichi, through at least June of 2012 . The direct water releases were trivial until after melt-through and groundwater incursion.
So. What does this mean for projections of how contaminated the Pacific waters off California (and Oregon, and Washington, and Alaska, and western Canada) will be when the main body of the plume settles offshore and continues to reach our shores for years thereafter? Basically it means what the California Coastal Commission says, only moreso: it will take some time to peak, and will diminish slowly over "several decades" or more once it does reach its peak. Depending mostly on whether Japan or the world ever bother to do anything about the ongoing waterborne releases of corium contaminated coolant and groundwater. The isotopes will also bioaccumulate in seafood at a higher rate, and will remain near or at peak for a longer period of time. The bioaccumulated levels get proportionally much higher than the overall levels in the seawater environment.
It's up to individuals to decide whether or not they care to partake of Pacific seafood, whether it's close to EPA's new outrageously high 'limits' or not. Radiation exposures are cumulative by nature, so the 'extra' that one may ingest from human sources is always to be considered 'extra' no matter how much natural radioactivity (like, say, potassium-40) is in the food on a normal basis. People can weigh risks for themselves and decide for themselves, nobody should have a problem with that. Alas, our government doesn't believe we need even the most basic of factual data on which to base our choices.
Nobody's going to get an immediately lethal dose of ANY radionuclide or combination thereof from eating a tuna sandwich or Alaskan king crabs for dinner. As a single exposure. It would simply be nice if we could be assured we're getting honest data about how contaminated the foods may be so we can make informed decisions about consumption.
In other words, instead of simply telling the public they can't weigh relative risks for themselves well enough to deserve honest data, they should simply give us the data and stop obsessing about what people might decide to do or not do with it. Oh... and stop with the not very clever technical deceptions to falsify or misrepresent the data.
One final note: The CCC report, even based on erroneous and/or deliberately false modeling/data, does note that the 'worst case' scenario (in case TEPCO has been lying, which they have) has the Daiichi Disaster tripling the amount of cesium in the North Pacific, over what was present prior to the disaster. When the cesium-134 decays below detection levels over the years, the cesium-137 complement in the North Pacific will still be double what it was on March 10, 2011 (once it is evenly distributed throughout the entirety of the North Pacific), and will remain so for at least 30 years beyond that as more keeps coming on out to keep the supply steady. That's something to think about for sure, despite the fact that it's only a fraction over the total amount of radioactivity in the ocean (and only a fraction of the gnarly shit that's coming out of Daiichi). Oh. And until the radioactive wastes stop coming out and are evenly distributed throughout the Pacific, that plume settling offshore is going to contain concentrated amounts of the whole radioactive stew.
That is why continued monitoring - and honest reporting - is highly advisable.
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* Strontium levels as of last week (late May, as reported by TEPCO) have reached 40 to 500 billion becquerels [Pbq] per metric ton [m3] in the basements of reactor buildings 1 through 4. That water is mixing with what is exiting the facility from the groundwater sinks beyond the seawall. As measured in wells at the cofferdam close to the cliff face. To the tune of ~450 to 500 tons per day or more.