The Swedish Radiation Safety Authority, SSM, and the Swedish Council for Nuclear Waste have submitted their responses to the Swedish government's referral on corrosion of the copper canister and problems with the cast iron insert. SSM does not consider that the referred documents and the question regarding the LOT experiment constitute a reason to change the regulator’s previous assessments that the repository for spent fuel has the possibility of being safe. The Swedish Council Nuclear Waste has concluded that there is a need for more research on copper corrosion before the repository can be put into operation. The Council proposes that more research be conducted after the government has given permission to build the repository, and that a separate government decision is to be made before the repository is taken into operation. MKG has released a press statement pointing out that there are already research results from the LOT experiment that can yield important copper corrosion results and be available in a relatively short time allowing the government to use them as an additional basis before taking a decision on the admissibility of the planned repository for spent nuclear fuel in Forsmark.
On September 23 the Swedish government sent out a referral regarding the nuclear waste company SKB's licence application to build a repository for spent nuclear fuel in Forsmark. The Swedish Radiation Safety Authority, SSM, and the Swedish Council for Nuclear Waste were asked to comment on new research regarding copper canister's protective capacity and the function of the cast iron insert. The government wanted an answer as to whether two scientific documents contain new information that could affect the government's upcoming decisions on whether to approve the licence. In addition, the government wanted an answer to the question of whether there is information from the LOT experiment at the Äspö hard rock laboratory that should be reported and developed and that is important for the assessment regarding the canister's long-term integrity.
The studies that were referred were scientific article on copper corrosion processes in the journal Corrosion Science, and a report on deformation aging in the cast iron insert from research at Aalto University in Finland. There is a link to a news article about the referral below.
On October 15 the regulator SSM answered the referral. The regulatory response to the government is that the scientific documents do not change the previous assessments made by the authority. SSM believes that SKB has the possibility to meet the regulatory requirements for a spent nuclear fuel repository. In addition, SSM states that the regulator does not consider that the copper corrosion results from the LOT experiment need to be reported further.
On October 21 the Swedish Council for Nuclear Waste, the government’s scientific advisory board, responded to the referral. The council has concluded that there is more need for copper corrosion research before a repository for spent nuclear fuel can be taken into operation. The Council proposes that more research be conducted after the government has given permission to build the repository, and that a separate government decision be made before the repository is taken into use.
MKG believes that the council's proposal has merits but wants to make it clear that there are research results from the repository-like LOT experiment that can provide important, perhaps decisive, knowledge in a relatively short time span so that in can be available before the government takes an admissibility decision on the nuclear fuel repository. On October 22 a press release was sent out to explain this.
What needs to be done is first to produce detailed corrosion studies of the most corroded surfaces in the two 20-year trial packages that were taken up in the autumn of 2019, something that the nuclear waste company SKB has so far refused to do (see picture of one such surface).
Thereafter, it is possible within a time span of six months to one year to carry out an experiment in the Äspö hard rock laboratory where a few new simplified LOT experimental packages are deposited in the same way as the original experimental packages. The oxygen in the packages is monitored and when it is consumed, which takes a few months, the copper surfaces on the packages are compared to the corrosion on the 20-year packages.
This provides a new scientific basis that can be important, perhaps decisive, for making the assessment of whether copper is a sufficiently good canister material for the nuclear fuel repository.
And the information can be a basis for the government decision on permissibility of the repository for spent fuel. Instead of doing more research after a decision to allow construction.
More information on the MKG press release on the importance of the LOT experiment can be found on the MKG Swedish web site here.
More information on referral response from the Swedish Council for Nuclear Waste can be found on the MKG Swedish web pages here.
More information on referral response from SSM can be found on the MKG Swedish web pages here.
A news article on the English MKG web pages about the government referral on copper canister issues can be found here.
Previous news articles on MKG’s English web pages: