Planned Centralized Radioactive Waste Processing May Allow Uncontrollable Reuse of Radioactive Waste as “Cleared” Waste

By Sueda Kazuhide (Radioactive Waste Campaign Kansai)

We have entered the age of full-scale decommissioning. Of all Japan’s commercial nuclear reactors, 24 are slated for decommissioning. The best-case scenario would be to enclose them tightly and keep them under control until their radioactivity decays. However, Japan makes it a rule to disassemble and remove the plants, while the issue of where to relocate the resulting huge amounts of radioactive waste has not been settled. Accordingly, at Tokai Power Station, Ibaraki Prefecture, the dismantling of which has begun in advance of others, the decommissioning work has been considerably delayed.

The “clearance” (low-level exemption) system was introduced to enable cheap dismantling of plants. This system permits waste with radioactivity lower than a certain level to be treated as “non-radioactive waste” and exempts it from control. The system was introduced in 2005 when the Act on the Regulation of Nuclear Source Material, Nuclear Fuel Material and Reactors underwent a damaging revision. It literally permits such waste to be used, firstly, for any purpose and, secondly, without any traceability records kept. However, as a result of a civil movement against the system, the industry promised to recycle the waste within the bounds of the industry and maintain traceability records at their own initiative “until the system is fully established.”

The power industry is deeply dissatisfied with these restraints, pointing out that they prevent the industry from proceeding with clearance system–based waste disposal and thus from smooth decommissioning. On December 28, 2021, the Atomic Energy Commission released a policy paper entitled “Approach to the Processing and Disposal of Low-level Radioactive Waste and Similar (Opinion),” which includes a recommendation of “expanding the recycling of cleared waste.” In the same FY2021, the Agency for Natural Resources and Energy entrusted a project of processing and testing cleared metal waste to a company in Fukui Prefecture. As part of this project, an expert panel was organized to review the recycling models to enable the reuse of waste in more applications. The panel stated that efforts should be made to increase recycling applications outside the power industry step by step, specifically, for the installation of monuments in public places and the production of metal equipment in public facilities.¹ In response to the proposal, the use of metal from cleared waste is finding increased use outside the power industry in Fukui Prefecture; cleared waste has been used to build bicycle racks at the municipal Mihama Lake Center and lighting fixtures at Tsuruga Technical High School and Fukui Minami High School.

On February 20, 2023, the Atomic Energy Commission finalized its “Basic Policy for Nuclear Energy,” which states: “It is desirable to reuse such material in increasing numbers of applications and accelerate efforts to persuade society to accept the clearance system.” In April 2023, the ministers related to nuclear power approved a “Future Nuclear Power Policy Direction and Action Plan,” which encourages efforts “to promote social acceptance to enable cleared material to be released without restraints.”

Proposed centralized processing of supposedly cleared waste collected from multiple plants

Another reason why waste disposal does not proceed smoothly based on the clearance system is that the procedure is complicated. Firstly, it is necessary to obtain approval from the NRA for radioactivity concentration measurement and evaluation methods. In the case of Tokai Power Station, waste that may be disposed of as cleared is selected, sorted, and classified, and if necessary, shredded or otherwise processed. The waste is then placed in specified types of containers, each with a volume of 1.3 m × 1.3 m × 1 m, not exceeding one ton in weight, after which radioactivity is measured for a period of about 12 minutes. The measurement results need to be confirmed by the NRA.

This attracted the attention of Fukui Prefecture, which is attempting to develop decommissioning-related industries through the Reinan E-Coast Plan. The above-mentioned Action Plan resolved by the ministerial meeting states that recycling businesses including municipal parties and Fukui prefectural organizations, should be nurtured and cooperation and collaboration with them sought. The national government is backing up this move.

What Fukui Prefecture aims at is to realize a centralized cleared-waste processing project by establishing a local joint venture, which would collect supposedly cleared waste (radioactive waste estimated to be disposable as cleared waste) from multiple nuclear power plants; perform pre-treatment such as decontamination; allow the waste to undergo all disposal processes such as shredding, decontamination, melting and radioactivity measurement at one site; inspect and approve of the resulting material as waste that can be exempted, and recycle it. Fukui Prefecture initially compared various plans: limiting central processing to melting, limiting the scope of central processing from shredding and decontamination to melting, and setting the scope of central processing from unpackaging and classification to inspection and approval. The prefecture decided on the scope of central processing explained above due to industrial demand for this range being the largest.

The biggest problem with this plan is that, to date, only waste that was inspected and approved as cleared was exempted from the regulations and proceeded to the melting process, while in the new approach, samples for radioactivity measurement, inspection, and approval are obtained after the waste has been melted. The prefecture says that, as a result of melting, some of the nuclides would be transformed into exhaust gas and slag, that fewer nuclides would need to be evaluated, and that cobalt 60, which is a major problem, would stay in the molten metal and would be uniformly distributed throughout the molten liquid, so that the entire amount of waste could be represented by a sampled volume of the liquid. Furthermore, the prefecture says that while the shapes of supposedly cleared waste are highly varied and conservative evaluation is required in this respect, uncertainties due to waste shape variation would be reduced because waste would be melted first, thus improving measurement accuracy. The melting furnace is planned to have a capacity of 10 tons. While at Tokai Power Station, waste is measured up to one ton at a time in the specifically designed container, Fukui Prefecture is apparently attempting to save labor.

In March 2023, the Nuclear Plant Decommissioning Study and Investigation Committee (composed of Iguchi Tetsuo, Professor Emeritus, Nagoya University, and others) in the Institute of Applied Energy prepared a proposal² to promote centralized processing, citing the CARLA plant in Krefeld, Germany and the Nyköping facility in Sweden as examples where waste is melted before the confirmation of clearance: “To establish a rational radioactivity evaluation method, power companies should clarify the impact and other possible influences on safety evaluation based on data to determine the nuclide composition ratio by the plant or by another base unit and to clarify the tolerable range of mixing and dilution of waste before clearance inspection and approval, and should realize communication with regulating authorities in cooperation with academic societies and industrial associations.”

Restraints may be thrown out the window

The Agency for Natural Resources and Energy communicated with the NRA on the basis of this proposal, and on June 21, the NRA confirmed the establishment of an opinion exchange forum with Fukui Prefecture and the Agency. This forum met twice in 2023, on July 31 and on October 11.³

The proposal unintentionally shows the problem pointed out at the June 21 NRA meeting. It says that if waste is melted before inspection and approval, dilution may occur, indicating the need to establish a tolerable dilution range. Regarding the melting process before inspection and approval, NRA commissioner Ban said: “To check that the waste radioactivity is no higher than the clearance level, not only measurement and evaluation but comprehensive evaluation is required in consideration of other information, such as the records of where the waste has been used. Once the waste is melted, such comprehensive evaluation would be impossible.” Commissioner Ishiwatari commented: “The central processing may start running uncontrollably once the proposal is received. It is important to proceed with this project step by step.”

In response to these indications, Fukui Prefecture said at the first opinion exchange forum that the proposed melting is not intended to mix and dilute waste whose radioactivity might exceed the clearance limit and that to prevent the mixing of supposedly exempted waste with different contamination properties, the waste from each power station would be handled separately. The prefecture further explained that, during a given year, waste from Tsuruga Plant Unit 1, as an example, would be processed first, and when its central processing was completed, the bricks on the interior of the melting furnace would be replaced to prevent the mixing of surface contamination, and then waste from Mihama Plant Unit 1 would be processed.

The Secretariat of the NRA confirmed that the project would be conducted within the boundaries of the existing regulations at the first forum, and at the second forum, the secretariat pointed out many technical issues. In addition to the means of ensuring that different types of radioactive waste and other material would not be mixed or diluted intentionally, these issues included what kind of containers would be used to carry supposedly cleared waste, in what form the slag resulting from the melting process would be disposed of, and while it is planned to return processed waste produced by the joint venture to the individual nuclear plants, what would be the timing for the waste to be returned and how it would be buried. Each single issue is scheduled to be discussed at the forums that are to meet once every several months.

Fukui Prefecture, on the other hand, held a fiscal year Reinan E-Coast Plan Promotion Meeting⁴ on October 24 and decided to establish a joint-venture stock company as soon as the NRA secretariat gives the green light. Once the company is established, the prefecture will start to design facility details and prepare transactions for required permissions and licenses.

Without civil monitoring, the restraints the civil movement won at the time when the clearance system was introduced may be cast aside, possibly resulting in the commercial distribution of frying pans made from nuclear waste. We are probably now on the cusp of this risk becoming a reality.

Note 1) Business Report

www.enecho.meti.go.jp/category/electricity_and_gas/nuclear/rw/library/2021/3fy_clearance.pdf

Note 2) Action for Rationalizing the Clearance of Waste Resulting from Decommissioned Nuclear Plant Disassembly

www.iae.or.jp/wp/wp-content/uploads/rep/op/nlr_2023-05.pdf

Note 3) NRA Secretariat and Fukui Prefecture: Opinion Exchange Forum Concerning the Centralized Cleared-waste Processing Project

www.nra.go.jp/NuclearRegulation/Fukui_ikenkokan_index.html

Note 4) Fiscal 2023 Reinan E-Coast Plan Meeting

www.pref.fukui.lg.jp/doc/dengen/r5ekaigi.html