IRID Review Of Contaminated Water Proposals (Including Ours)

33  Groundwater bypass http://irid.or.jp/cw/wp-content/uploads/2013/11/RFI_Result1118_1_51.pdf
114 Final water treatment http://irid.or.jp/cw/wp-content/uploads/2013/11/RFI_Result1118_1_21.pdf
115 Underground zeolite http://irid.or.jp/cw/wp-content/uploads/2013/11/RFI_Result1118_1_11.pdf
544 Drainage canal passive filter http://irid.or.jp/cw/wp-content/uploads/2013/11/RFI_Result1118_1_31.pdf
545 Port filtration http://irid.or.jp/cw/wp-content/uploads/2013/11/RFI_Result1118_1_31.pdf

Over all we were mostly pleased with the reviews and commentary the IRID board had on our proposals and the other proposals submitted. There was some concern that they appear to have dismissed all ideas for tritium handling even though there were a wide variety of viable solutions including just holding the water until the tritium decays.

33  Groundwater bypass (our plan here)

“As different concepts from impermeable walls, there were many proposals that groundwater is collected near the mountainside boundary and drain to the sea directly. Conventional methods such as trench, tunnel and well are combined in practical. There is a proposal from the Japanese Society of Limnology that trench should be installed at the mountainside which will not be affected by the contamination from the reactor buildings”

“The idea of “passive bypass” in the mountain area is innovative, and has a significant potential to be transformative in terms of water balance. Physical installation of any system will be in an up-gradient area that is less contaminated with less interferences. It would simplify logistics and reduce costs. We recommend starting up the existing bypass wells and operating the active bypass system. However, the bypass wells are down-gradient of water storage tank area. In case leakage occurs from tanks, the active bypass wells would become contaminated. We should provide additional countermeasure such as bypass near the mountain.”

While we disagree with the operation of the bypass wells inside the plant due to their contamination, IRID does see the major benefit to a bypass system located closer to the mountains as we suggested in our proposal. It sounds like IRID will move to the planning stages for something similar to our proposal.

114 Final water treatment (our plan here)

“In regards to storing tritium-contained water, we received many proposals on solidification, such by plaster, gelling and freezing. In addition, much information regarding the environmental release was submitted. Diluted release to the ocean is approved internationally, and it is said that the method achieves many results. In regards to dilution, we received some specific measures, such as use of the existing plants (1F5&6, 2F), and the dilution with rainwater or groundwater. In regards to the atmosphere release, we received proposals such as using the natural evaporation, geothermal utilization, and the existing waste treatment systems. In regards to underground, the isolation from the living environment until tritium is sufficiently attenuated is mentioned as a benefit; however, understanding the underground structure is a challenge. Other proposals were about degradation and disappearance”

“In order to store condensed tritiated water stably and for a long term after separation, the impact of radiolysis and Helium gas generated by the decay of tritium should be taken into account. There was no proposal that included those considerations. Moreover, since the impact of possible leak becomes larger than before the concentration, the storage of condensed triturated water must be judged carefully including the advisability of separation. Environmental release (mainly diluted discharge to the ocean) of tritiated water at a value less than the authorized limit has been carried out at nuclear facilities in and outside Japan. This method is high in technical implementability, and the risk is small to the environment. When the application of environmental release to Fukushima Daiichi is investigated, utmost consideration for prevention of a damage caused by rumors, and sufficient explanation to stakeholders are required.”

It is disappointing that IRID has dismissed the impact of dumping the contaminated water into the sea without further exploration of the other proposals submitted. The committee also falls back on an industry trope of “rumors” and trying to make the public “understand”. The reality is that this would end up being a considerable dump of tritium over the years that water would need to be disposed of and be far larger than the regular releases by operating reactors. IRID also fails to address the problem that this water contains iodine 129 and cobalt 60.

115 Underground zeolite (our plan here)

“Non-cement, non-polymer solidifying agents, which are the materials used for construction since the 60s, excel at absorbing substances. The post-solidification state is similar to concrete. It may be worth examining for application to other wok of recovery at Fukushima Daiichi.”

Limited related review related to this proposal was given. They seem open to various ideas of entrapment of contaminated water or substances with concerns for final disposal.

544 Drainage canal passive filter (our plan here)

“There were many proposals about in-situ adsorption processing in the harbor. A lot of proposals were about sorbents such as a non-woven fabric and particle. Furthermore, there were 13 proposals on using sorbents of powder, zeolite and mineral”

IRID made a number of comments on this and a wide variety of other filtration suggestions. The main concerns involved sufficient filtration of precipitates and identified the zeolite variety with the best capability of capturing cesium and strontium 90 in sea water conditions. This is partially relevant for this type of filtration system as seawater (or chlorides) are frequently involved in water spills and runoff.

545 Port filtration (our plan here)

“There were many proposals about in-situ adsorption processing in the harbor. A lot of proposals were about sorbents such as a non-woven fabric and particle. Furthermore, there were 13 proposals on using sorbents of powder, zeolite and mineral. In addition to 3 proposals on installing an adsorption fiber under seawater,”

“The R&D efforts such as feasibility studies on the development of efficient sorbents for Cs and Sr removal from the actual seawater are required. It is important to understand radiochemical state of the seawater sufficiently at first, and to assess the removal technologies. The removal of the radioactive ionic Cs from the seawater is not an issue since sorbents have been almost proved to be efficient in the seawater. However, the removal of the radioactive Sr is known to be theoretically difficult, and it takes a long term to further purify the seawater because of its huge volume. Due to this, selection of materials that efficiently remove radioactive materials from the seawater should be made as a short-term measure. In addition, R&D efforts on the development of promising techniques to remove radioactive Cs and Sr should also be increased in a continuous manner. In view of the existence of stable (non-radioactive) Sr and the concentration of Ca and Mg in the seawater, it is realistic to adopt proposals which are grounded on scientific evidence, and consider the amount of precipitant added in the co-precipitation method. There is some promising sorbent for recovery of Sr in the seawater. Not only the co-precipitation based process but also the absorption process should be selected and preferentially applied from the viewpoint
of ensuring sufficient decontamination efficiency and minimizing the volume of secondary waste generated. 

An ex-situ approach for an immediate application (pump-up and purification) may be desirable compared to an in-situ approach because the target seawater cannot be stirred enough, and the purification speed is low in an in-situ approach. In addition, the co-precipitation process should not be applied for an in situ purification since the active precipitate could settle at the bottom of the sea. It will result in difficulties of deposit collection.

When evaluating the applied technologies, it is necessary to keep in mind that the harbor is connected to the open sea because it is only divided by a silt fence. Closure of the harbor should be considered as an option because without closing the harbor from the open sea, the unrealistic amount of stable Sr should be removed from the seawater. If it is hard to close the entire harbor from the open sea because of the unknown amount of groundwater inflow or from an economic aspect, it is effective to close only the open conduit which has a high concentration of radioactive materials, and purify the seawater within it.”

IRID seemed to be in agreement with our proposal on sealing off the harbor and the benefit of a pumped up filtration system. Again the selection of filtration media for the most efficient contaminant capture needs to be researched.

Over all the process seemed to be productive and many research submissions consisted of similar ideas, lending credibility to certain concepts. IRID will begin a similar proposal submission process for corium location and reactor fuel removal technology soon.

image credit | cartoonmovement.com