Despite the massive criticism from researchers and environmental organizations, the Swedish Radiation Safety Authority (SSM) on March 11 gave its approval, in an opinion to the Swedish government, of how the nuclear waste company SKB carried out analyses and presented results of the copper corrosion in the LOT experiment. The experiment with copper tubes embedded in clay has been operational in the Äspö hard rock laboratory for 20 years. The regulator has just ignored that the company unscientifically has not reported in detail the corrosion on the most corroded parts. MKG is now sharpening its criticism of SSM.
The Swedish Radiation Safety Authority (SSM) has on March 11 published a report on the quality review that the regulator has carried out since September 2020 of the analysis and reporting that the nuclear waste company SKB has done on the copper corrosion in two 20-year-old experimental packages in the LOT experiment at the Äspö hard rock laboratory near the Oskarshamn nuclear power plant. The packages were retrieved in the autumn of 2019.
The SSM assessment is in summary that the nuclear waste company has performed the tests with a high quality and that the results are reliable. SSM agrees with SKB that the reported results do not add knowledge about how copper behaves as canister material in the planned nuclear fuel repository in Forsmark.
The Swedish NGO Office for Nuclear waste Review (MKG) considers it bad enough that the nuclear industry is trying to withhold facts from the public. But it is far worse that the Swedish regulator now announces that it accepts this behaviour, which entirely unscientific. And forwards this opinion to the government.
The report from the nuclear waste company SKB was published on October 1, 2020 (SKB TR-20-14). It then became clear that the company had excluded detailed reporting the corrosion on the parts of the copper canisters that had been hottest as well as on the bottom plate that had been in contact with wet sand instead of clay. MKG has delivered four scientifically based inputs to SSM during the quality review, but the regulator has basically ignored this as well as input from highly respected copper corrosion expertise from the Royal Institute of technology (KTH).
MKG considers it quite clear that the LOT experimental packages at the surface of the copper tubes and bottom copper plate have been in an environment without oxygen gas (anoxic) since the start of the heating of the packages. The packages were at that time filled with anoxic ground water from a hole drilled into the surrounding bedrock. It is known that microbial activity keeps the water anoxic and also consumes the oxygen in the surrounding environment. There has been an extraordinary and unexpected amount of copper corrosion in the packages. SKB has not shown any pictures of the corrosion on the hottest part of the copper tube but below is a picture of the anoxic corrosion on the bottom plate. Basically, the plate should still be quite unaffected by corrosion as the water in contact with the plate did not contain free oxygen gas. Instead, it is heavily corroded, and the corrosion is very likely even worse on the hottest surfaces of the copper pipes that have been even warmer.
Copper corrosion on the base plate of the LOT package A3 after 20 years (Source: SKB)
MKG considers it remarkable that SSM accepts the SKB copper corrosion reporting in the LOT packages. The company has not carried out detailed analyses of the most corroded copper surfaces. If this had been done, MKG is of the understanding that it would be clear that copper cannot be used as a capsule material in the planned spent fuel repository in Forsmark.
The nuclear waste company has completely unscientifically stated that they have chosen to study another part of the central copper pipe with less corrosion, because they had cut it away anyway for other reasons. The company says that they do see the need to study the bottom plate, which is very corroded because it has been in contact with sand and not clay. These are not scientifically sound reasons for avoiding the full extent of copper corrosion. Not to do detailed corrosion studies on the most corroded surfaces is not an acceptable approach if the most knowledge is to be gotten from the LOT experiment.
MKG cannot draw any other conclusion than that the company did not want to publish the results from the most corroded parts as doing so would confirm that copper does not last for the hundreds of thousands of years needed to prevent radioactivity from leaking from the repository.
MKG wants the Swedish Radiation Safety Authority to restart the quality assurance project and ensure that the nuclear waste company SKB makes and publishes detailed studies of the most relevant copper surfaces, i.e., the parts of the central copper pipes that have been most heated and the bottom plates that have been in contact with oxygen-free water and sand. This has to be done with full transparency and independent researchers should also get access to materials to study.
MKG has on June 11 together with the member organisations the Swedish Society for Nature Conservation (SSNC) and the Swedish Friends of the Earth, wrigtten an opinion as a legal brief to the government recommending that such studies be done before the government takes a decision on the permissibility of the application to build the spent fuel repository in Forsmark.
Below are also links to more news articles in English.
The Feb 4 article contains the four MKG inputs to the SSM quality assurance review, as well as comments on the LOT experiment from qualified copper corrosion expertise from KTH.
The June 11 link is to the news article where MKG and its member organisations send in a brief to the government about LOT and other issues.
See also the following news articles on MKG:s English pages: