The word "uncontaminated" in the title above is in quotation marks, because there may be radionuclides left in the groundwater to be released, particularly tritium, even though it is the water drawn from the wells placed on the west side of the reactor buildings - i.e. before the groundwater enters the reactor buildings and gets contaminated.
From Jiji Tsushin (2/3/2014), after the regular press conference by TEPCO:
Fukushima I NPP targets set for releasing groundwater into the ocean, tritium less than 1500 Bq/L
On February 3, TEPCO announced the operating targets for densities of radioactive materials in groundwater to be relased into the ocean. The groundwater is drawn before it enters the reactor buildings and gets contaminated. The targets for cesium-134 and cesium-137 will be less than 1 Bq/L each, all-beta less than 5 Bq/L, and tritium less than 1,500 Bq/L.
The groundwater release is part of the plan to reduce contaminated water. The densities of radioactive materials are less than 1/4 of the legal limits for release into the ocean. TEPCO will talk with the local fishermen to obtain their understanding of [consent to] the release.
If the densities are above the operating targets, the release will be suspended and the water will be purified before the release resumes. For beta nuclides, TEPCO plans to purify until the density is less than 1 Bq/L, lower than the operating target.
And here's METI (Ministry of Economy, Trade and Industry)'s effort in persuading the fishermen.
From Kyodo News (2/3/2014):
Vice Minister of Economy asks National Federation of Fisheries Co-operative Associations for understanding of the start of groundwater bypass
Vice Minister of Economy, Trade and Industry Kazuyoshi Akaba asked National Federation of Fisheries Co-operative Associations for understanding of the start of groundwater bypass, which is part of dealing with the contaminated water at Fukushima I Nuclear Power Plant. The groundwater bypass will draw groundwater and release the water into the ocean.
[Vice Minister Akaba said] METI will apply the operating standards that are stricter than the existing standards in radioactive material density in the groundwater that will be drawn, in order to mitigate concerns from fishermen.
The groundwater that leaks into the reactor building is one of the causes for increase in contaminated water. According to the groundwater bypass scheme, the water will be drawn before it gets contaminated. However, concerns for baseless rumors remain strong particularly among fishermen, which has prevented the scheme from being implemented.
I wonder how TEPCO is going to "purify" the water to less than 1Bq/L. My guess is dilution, particularly if it is tritium which cannot be effectively removed on a large scale.
But it probably doesn't matter, as one day later Minister of Economy, Trade and Industry says METI has already obtained "a certain level of understanding" from the fisheries co-op.
From Jiji Tsushin (2/4/2014):
Minister of Economy Motegi says a certain level of understanding from the fisheries co-op in dealing with the groundwater at Fukushima I NPP
In the press conference after the cabinet meeting on February 4, 2014, Minister of Economy, Trade and Industry Toshimitsu Motegi said [the ministry] has obtained "a certain level of understanding as to the necessity" of the groundwater bypass plan from the National Federation of Fisheries Co-operative Association in dealing with the contaminated water at Fukushima I Nuclear Power Plant. Vice Minister Kazuyoshi Akaba had met with Hiroshi Kishi, Chairman of the National Federation of Fisheries Co-operative Association on February 3 to explain the outline of the plan and ask for understanding.
So the National Federation of Fisheries C-op Association will bear down on the Fukushima Federation of Fisheries Co-op Association, who will then bear down on the local Fisheries Co-ops in cities like Iwaki. The local Co-Ops will bear down on individual fishermen, who will probably need little persuasion, as they are eager to resume fishing.
TEPCO/METI plan to release groundwater seems to be back on track, as if the ground contamination in the very area where the wells were dug for the groundwater drawing had never happened in August 2013.
Right near where the wells are, there are huge tanks, mostly riveted together and meant to last for no more than 5 years, that contain highly radioactive (mostly beta nuclides, not gamma) waste water after reverse osmosis (desalination) treatment. Several of the tanks in the area were found to have leaked this waste water although no one knows exactly how much waste water leaked or how it leaked, and the leak may be slowly finding its way towards the wells. The elevated levels of tritium have already been measured, although they are well below the operating target of 1500 Bq/L.
Locations of the wells for drawing groundwater for the groundwater bypass scheme, and the sample water analysis (from TEPCO, 1/30/2014): the highest contamination of tritium recorded was 1,000 Bq/L from No.12 well on 12/24/2013.
Latest measurement of contamination levels in the H4 tank area, located southeast of the wells (from TEPCO, 2/6/2014):
For more on the "RO Waste Water Leak of August 2013", click here.
Nuclear Regulation Authority is yet to approve the operating targets, so all is not yet clear for TEPCO/METI. It is muddled as ever as to who is in charge of regulating TEPCO on the Fukushima I NPP accident cleanup efforts. It is supposed to be NRA, but it is increasingly tied up with the evaluation of nuclear power plants under the new guidelines in preparation for the restart. It looks METI is there (as it has always been there) to give the plant operators like TEPCO a way out, a bypass around the regulators.