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Holistic approach to repository research: GRS's geoscientific laboratory

Dr. Tina Scharge is head of the geoscientific laboratory of GRS in Braunschweig. The laboratory is part of the GRS repository research centre. In an interview, Tina Scharge talks about the tasks of the laboratory, her daily work and the challenges of repository research.

Ms. Scharge, you are the head of GRS's geoscientific laboratory. Could you briefly explain the tasks of the laboratory to us?

Of course. We have two large, independent fields of work: geochemistry and geotechnics. In geochemistry, we do routine work, as is also the case in other laboratories – in other words, chemical analytics. For example, we get solutions from the mines in the surrounding area and analyse them with regard to their salt content and heavy metals. On the other hand, we work on research tasks and look at chemical processes that can take place in a repository. In the field of geotechnics, we investigate the properties of the host rocks and sealing materials that are suitable for a repository. We do this not only here in our laboratory, but also in so-called underground laboratories under real conditions, such as those that prevail in a repository. Overall, experimental investigations are a large and important part of repository research at GRS. By the way: we do not work with radioactive substances in our laboratory. It happens again and again that people think this because we are part of our repository research centre here.

You were just talking very generally about mines. Which ones do you mean?

By that I mean the Asse and Konrad. But we also had samples from Morsleben or Gorleben.

Could you briefly outline the path a sample takes in your laboratory?

The sample is taken by the customer himself or sometimes by us in the mine. A colleague with a helmet and miners' clothes descends into the respective mine up to a depth of 1,100 metres. The sample is then packed and transported to the laboratory. When arriving at GRS, the receipt of the sample is documented. Each sample is assigned a unique laboratory number to avoid confusion. In addition, we check whether the sample is in proper condition. Before the actual examination, we make some preparations. In the case of liquid samples, this can be dilution and acidification, for example. For solid samples this can be drying, crushing and homogenizing. Geotechnical samples must be brought to certain dimensions in the workshop so that they fit into the testing machines. The path of the samples after the test is very different. Some samples are disposed of after a short time, others are stored for a longer time, and some samples are returned to the customer.

Which substances do you analyse in the geochemical field?

Most samples are highly saline solutions. These are solutions with a very high salt content, such as those found in salt mines. Here, we analyse the density and the main components sodium, potassium, magnesium, calcium, chloride and sulphate with different technical devices. Then – depending on the order – the secondary components are analysed. Typically, these are bromide, iron, lithium, lead, copper and zinc, but many other substances are also possible. Solid samples can be tested for the same components after they have been prepared. We also have the possibility to determine the mineral phases and thus which salts a substance is composed of. Gaseous samples can be analysed for hydrogen, oxygen, carbon monoxide, carbon dioxide and small hydrocarbons.

Are there provisions for the analysis of certain substances?

Some of the analyses are carried out in accordance with DIN standards. This means that there are exact, uniform procedures throughout Germany for the analysis of certain substances. The reason for this is that the results of all laboratories should be comparable. This is only possible if you can be sure that the results were obtained using the same method. However, for some tasks, such as the analysis of highly saline solutions, there are no standards. Here, we use methods that we have developed ourselves.

What technical equipment does the laboratory have?

Here in Braunschweig, we have a large number of different analytical instruments for chemical analyses: various devices for multi-element analysis, chromatographs, a titration system, a UV spectrometer and much more. In addition, we have two glove boxes in which we work hermetically sealed under a so-called inert gas atmosphere. In geotechnics, we have various testing machines for rock-mechanical investigations. In many of the machines, we can vary the temperature and perform permeability and ultrasonic measurements. Some of the tests take several months, some even years. For the preparation of the samples, the laboratory has its own workshop with machines that are normally used in metal processing: lathe, milling machine, saws, welding machine and drill press.

How does a typical working day in the laboratory look like?

The typical working day does not actually exist. The fact that, in addition to routine work, laboratory tests and method development are also required makes the work very varied. This is just as true for the laboratory staff as it is for me.

And do you work in the laboratory yourself?

Well, I'd say most of my work takes place at my desk. I evaluate the data from the laboratory, write test reports and am in direct contact with customers. And that's where sometimes things have to happen quickly. It has already happened that we got a call on a Friday and were informed about solution inflow into the Konrad mine. We had to go there on the same day and pick up the sample. Then I had to see if there was still someone there on Friday afternoon who could analyse the sample. There are parameters that have to be analysed directly within the first 48 hours. But I also have meetings with the project managers, who bring their project ideas to me and ask “Is that feasible at all? How many hours do we have to plan? Do we have the equipment for this?” We hold laboratory meetings once a week. We also have regular audits because we are accredited as a testing laboratory. And the organisation around the topic of occupational safety also falls within my area of responsibility. The work is incredibly varied.

What qualities do people need to have who work here in the laboratory?

Above all, people in the laboratory must be open to new things and be prepared for intensive training. It is rare to have acquired all the knowledge we need from training or previous employment. Especially in geotechnics, where the testing machines are no off-the-shelf devices, you have to learn a lot at the beginning. But even if you have been working in the laboratory for some time, you always have to open up new fields of work. And you have to be flexible. We have many different devices and methods. Every staff member has a device that he or she supervises. But we are a relatively small team. Therefore, everyone has to be able to operate other devices.

That sounds very varied. What kind of education do the staff members have to have?

Due to the different tasks, the staff come from the most diverse occupational groups. Chemical laboratory assistants, chemical-technical assistants, but also a mining technician, an electrical engineer and staff who have completed their education in mechanical engineering work in the laboratory.

So what are the stages of your career before being appointed head of the laboratory?

I have been a research assistant until 2014. I did project work and also worked in the laboratory. In particular, I developed thermodynamic data for elements relevant to repositories, conducted literature searches, evaluated experimental data that we determined here in the laboratory or found in the literature. I used the data to carry out geochemical modelling. Then, the former head of the laboratory retired. A short time later, I took over the job as head of the laboratory.

In your opinion, what is the biggest challenge in the field of disposal?

From a scientific point of view, I find it challenging that a repository must be safe for a million years. Even if we run experiments in our laboratory for several years, it is a big step to scale it to one million years. In addition, there is the multitude of processes that can possibly take place in a repository. It is very demanding to recognise and consider them all. Another challenge, in my opinion, is public acceptance. Especially here in the region, the Asse is an incredibly important topic. Many people feel affected by it. I keep hearing that some believe that we also have the ionising radiation from the radioactive substances up here. I can imagine that many people lack the scientific background to be able to properly assess the situation with radiation exposure. Confidence is certainly also a very important matter. People have before their eyes the pictures in which the drums containing the waste were dumped into the Asse. A few decades later it turned out that today there is a threat of major water ingress and many people have lost confidence. In the meantime, a lot has changed. There is a new operator and the waste is to be retrieved, but I have the impression that still many people lack confidence.

Do you have any idea how that could change?

What is certainly very important is that objective information about the facts is provided. Scientific institutions like us are also in demand here. Actually, this is how I experience it again and again in personal conversations when I am asked about the topic. I notice that there is a lot of interest, but also a lot of open questions.

Thank you very much for this interesting interview!