On Friday, Tokyo Electric Power Company said they will eventually release decontaminated Fukushima Daiichi waste water to the sea. The company has been reluctant to consider discarding low-level waste waters to the sea because of the reaction spawned by their releases made the first week of April, 2011. Tepco says they will eventually run out of room for low-level waste water storage tanks, thus releases are inevitable. Tepco says they will not make the discharge until the waters meet all Japanese radiological standards. Because of Tokyo’s overly-restrictive track record on setting radiological limits, Tepco may as well be waiting for pigs to grow wings.
F. Daiichi currently has about 275,000 tons of low level waste water in storage, and the numbers go up about 300 tons a day. They process 700 tons/day of raw radioactive liquid from the four turbine building basements, use 400 tons/day for cooling of the three damaged fuel cores and send the extra 300 tons/day to storage. The problem is the volume of groundwater which seeps into the four basements daily, so the amount of water contained in the flooded rooms stays the same. Tepco takes it out and groundwater puts it right back in.
The existing waste water decontamination system removes radioactive radioactive Cesium very well (a decontamination factor of 5,400), so the stored waste waters only have about 10 Becquerels per milliliter Cs-137 content. That’s actually better than the system was designed to do. But, there are still about 60 detectible radioactive isotopes that remain, and detectible is unacceptable in Japan. Tepco is planning a new system that will sufficiently remove all of the remaining isotopes to meet national standards…except for Tritium. Since Tritium is a gas which can become part of the water molecule itself, a dedicated Tritium removal system must be developed. Apparently no such technology currently exists in Japan. It does in Canada, if memory serves, but not Japan. (It should be noted that nuke-plant Tritium production is very, very small when compared to Cesium, Iodine and Strontium.)
Tritium is a naturally-occurring isotope of Hydrogen with a half-life of about 20 years. Instead of a single proton in the nucleus, there is a proton and two neutrons. The proton/neutron ratio make the nucleus unstable, so eventually one of the neutrons spits out an electron and becomes a proton, transforming the atom into Helium. The ejected high-speed electron is called a Beta particle, which is known colloquially as Beta radiation. Betas cannot penetrate even the thinnest tissue paper because of their inherent physical properties, so outside the body they are effectively harmless. In massive concentrations, Betas can redden the skin similar to sunburn, but that’s about the extent of the external effect. However, if a Beta-emitter is inside the body, it could result in localized ionization of living tissue. Ionization due to Beta can cause biological and chemical anomalies.
The Beta released by Tritium is very weak – about 50 times weaker than the Beta produced from Cesium-137. As a gas, Tritium is quite harmless. On the other hand, Tritium can switch places with regular hydrogen on the water molecule and be ingested. If ingested, the length of time “Tritiated” water remains in the body is about 30 days. Because the radiation is weak and the body’s retention time is relatively short, the international standards for Tritium are a considerably lower than with Cesium. America has one of the lowest Tritium limits in the world at 750 Becquerels per liter, compared with a Cs-137 limit of 7.5 Bq/liter. In other words, America believes Tritium-based risk to be 100 times less than Cs-137-based risk, and that’s just the tip of the issue’s iceberg. If Japan was using the American example to set its Tritium health standard, Tepco’s job might not be unmanageable. However, Japan currently has no Tritium-based standards!! This means Tepco has no idea how extreme a Tritium removal process must be. Considering the existing Japanese government’s track-record on establishing radiation standards, they could very well cut America’s already low limit by another factor of ten, which would provide no additional level of safety in any way, shape or form! They have done similarly unrealistic radiation standard-setting before, and there is no reason to think they are going to stop now.
It is time for the new regime in Tokyo to do the right thing and adopt the American 750 Bq/liter limit for Tritium, at the very least. Is it safe? Is the Pope a believer? Australia’s limit is 76,000 Bq/liter. Finland’s sits at 30,000. The World Health Organization sets their recommendation at 10,000 Bq/liter, the same as nuclear-averse Switzerland. Russia’s limit is 7,700, and Canada’s at 7,000 Bq/liter. In comparison, adopting the American limit is very, very safe. Tokyo should set a reasonable Tritium limit and not concern itself with exaggerated what-if scenarios. Let the Press howl. Let the antinuclear prophets of doom predict the end of Asian life as we know it. Do the right thing!