23rd January 2020 (Original post was made on 16th January)
Fukushima Daiichi Nuclear Power Plant from Namie Town (Nov 2019)
On December 23, 2019, the Subcommittee on Handling of ALPS Treated Water, established by Japan’s Ministry of Economy, Trade and Industry (METI) to discuss how to deal with the ever-growing volume of water from the so-called Advanced Liquid Processing System (ALPS), released a draft report (referred below to as “draft report”) offering three proposals to deal with treated contaminated water from the damaged TEPCO Fukushima Daiichi Nuclear Power Plant. The draft report proposes discharge to the sea, vapor release, and a combination of the two.
All three options would spread radioactive substances into the environment. The draft report ignores alternatives for long-term storage on land, including large tank storage and mortar solidification.
As of October 2019, about 1.16 million cubic meters of ALPS-treated contaminated water was stored in 960 tanks. The total amount of tritium was estimated at 856 trillion Becquerels (Note 1). Approximately 80% of the water stored in the tanks exceeded regulatory standards to be discharged. (The sum of the ratios of actual concentrations to regulatory standards for 62 radionuclides other than tritium exceeded 1, but for any discharge to satisfy regulations this should be less than 1). This includes radionuclides such as iodine-129 and strontium-90. TEPCO says that if water will be released to the sea, it will perform secondary treatment to ensure the concentrations comply with standards.
Regarding the contaminated water, Toyoshi Fuketa, chairman of the Nuclear Regulation Authority, has repeatedly stated that dilution and ocean release is the only realistic option. Media broadly reported a statement made at a press conference last fall by Japan’s former environment minister, Yoshiaki Harada, that discharge to the sea is the only option.
But although realistic proposals have been made for land-based storage, the authorities have not given them fair consideration, and mainstream media in Japan have not reported on those other proposals.
Proposals for storage in large tanks not properly considered
A technical committee of the Citizens’ Commission on Nuclear Energy (a citizen-based think tank that also includes experts in the field of large industrial plants) has submitted proposals to METI regarding land-based storage using large tanks, and also mortar solidification technology (Note 2).
The large tank storage proposal involves constructing large dome-shaped tanks, at 100,000 cubic meters each, equipped with water seal vents. For the site, the proposal was choose from the planned sites of (cancelled) reactor units 7 and 8, a soil dumping area, or an area at the back of the Fukushima Daiichi site, after obtaining local consent. The proponents said that it would be possible to store about 48 years’ worth of new ALPS-treated water by constructing 20 tanks on an 800 x 800 meter site and also, by gradually replacing existing tank on the existing site with larger ones.
At a public hearing organized by the ALPS Subcommittee Secretariat in August 2018, representatives from the fisheries industry and many other participants opposed the idea of discharging contaminated water into the sea, and instead called for long-term storage on land. In response, Subcommittee chair Ichiro Yamamoto promised to consider on-land storage as one option.
The Subcommittee finally began to discuss land-based storage a year later. That was at the Subcommittee’s 13th meeting, on August 9, 2019. On the topic of storage in large tanks, the only statement from TEPCO was that it had considered the idea but found it had significant disadvantages. No questions ensued and there was no further discussion of the topic.
The supposed disadvantages, as claimed by TEPCO, were that large tanks were not any more efficient than regular tanks in terms of site usage, that there was potential rainwater contamination of tank contents, and that there would be large a discharge in the event of damage to a tank.
However, it is well known that large tanks are already used extensively around the world to store oil and other liquids. Regarding rainwater mixing with tank contents, a dome-type design would avoid such a risk. In terms of discharge prevention, the large tank proposal by the Citizens’ Commission on Nuclear Energy included the installation of a protective berm.
Clearly, the ALPS Subcommittee should not have relied on such a one-sided explanation from TEPCO.
Proposal for mortar solidification was completely ignored
The mortar solidification proposal from the Citizens’ Commission on Nuclear Energy is a method already used in the disposal of contaminated water at the Savannah River nuclear reservation in the United States (South Carolina). There, contaminated water is solidified into mortar by being mixed with cement and sand, then the mortar is poured into concrete tanks and stored partially underground.
Citizens’ Commission on Nuclear Energy’s Mr. Yasuro Kawai (a former plant engineer) was involved in preparing the proposal. He explains it this way: “The advantage is that solidification allows you to eliminate the risk of discharging radioactive substances into the sea. But the mixing of contaminated water with cement and sand reduces the volumetric efficiency by a factor of about 4. That is a disadvantage. Even so, with an 800 x 800 meter site, there is enough space using mortar solidification and storage for about 18 years’ worth of contaminated water at this site.”
The ALPS Subcommittee Secretariat tried to dismiss that proposal, saying it is unproven.
However, aside from the experience at the Savannah River nuclear facility, much of the low-level waste generated elsewhere during nuclear power plant operation has been solidified in mortar and then placed in trenches or pits. This is a very simple and practical approach. It makes no sense to write off the mortar solidification proposal by saying it is unproven.
Is there really insufficient space at the existing site?
The discussions about the Fukushima Daiichi site are still incomplete.
The site usage plan presented by TEPCO includes temporary storage facilities for spent nuclear fuel and fuel debris, storage of materials and equipment, and “mock-up” facilities, as well as research facilities. For some of these items, it is not really clear why they need to be located on the site (Note 3).
Furthermore, officials recently announced that the plan to remove spent nuclear fuel will be postponed for up to five years. As for the removal of debris from the damaged plant, the disposal method has not yet been determined. The very idea of debris removal still needs to be given serious examination.
Committee members posed various questions. For example: “Looking at the Fukushima Daiichi Nuclear Power Plant site usage, can’t you install tanks with the same capacity as existing tank capacity on the north side of the site where there is currently a soil dumping area?” “If the site is not big enough, why not expand the Fukushima Daiichi Nuclear Power Plant site?”
If large tanks can be also installed on the current soil dumping area on the north side of the site, an estimate 48 years’ worth of treated water can be stored in the future.
Subcommittee members repeatedly asked if it was possible to move soil from the current soil dumping area. The Secretariat of the Nuclear Regulation Authority provided only vague responses stating that standards for moving soil offsite need to be discussed.
Regarding the soil now accumulating in the soil dumping area, TEPCO explains that it ranges from a few to several thousand Bq/kg in radioactive levels (Note 4). If that is correct, the soil can be moved.
As for the potential to expand the site for storage tanks, the Secretariat stated: “Regarding the planned site of the intermediate storage facilities outside the Fukushima Daiichi Nuclear Power Plant, we explained our intentions to the local community. They have accepted that site use for the reconstruction of Fukushima, so it is difficult to use it for any other purpose” (Note 5).
Our view is that, obviously, it is very important to provide an explanation to the community and obtain local consent. But it is premature to come to the conclusion that it is too difficult to expand the site without having actually made any effort.
ALPS Subcommittee draft report is full of problems
It seems that the ALPS Subcommittee’s draft report released on December 23 does not faithfully reflect the Subcommittee’s discussions. Rather, one gets the impression that the Secretariat and TEPCO have strongly influenced its conclusions recommending discharge to the sea, vapor release, or a combination of the two.
For any mention of the above-mentioned proposal to use large tanks, the document simply adheres to TEPCO’s explanation.
Regarding the removal of soil from the dumping area, the report reaches a conclusion that includes points not even discussed by the Subcommittee. For example, it concludes that it would be difficult to move the soil off-site, because the condition of the soil on-site is not known, and no clear plans and storage methods exist regarding a destination to deposit soil from on-site. (Note 5)
Despite the above situation, unless members of the Subcommittee express clear objections, the Secretariat-directed draft report will be regarded as the official output of the Subcommittee.
Deliberations by the ALPS Subcommittee on the above topics are nearly over. Within a number of days, a subcommittee meeting will be convened where the report is expected to be finalized. After that, it is likely that some process will be initiated to gain local consent.
However, local fishermen are already ramping up their fight against the discussions that were biased in favor of discharging contaminated water into the sea.
Officials should take another serious look at land-based storage
ALPS Subcommittee should take serious look at the land-based storage proposals and listen to the opinions of a wide range of citizens, including the local community.
Note 1: Documents released by TEPCO on November 18, 2019.
Note 2: Citizens’ Commission on Nuclear Energy, “Comments on the handling of ALPS treated water,” October 3, 2019.
Note 3: Document 3 at the 14th ALPS Subcommittee meeting.
Note 4: TEPCO remarks at the 15th ALPS Subcommittee meeting.
Note 5: Document 4 at the 16th ALPS Subcommittee meeting.