PART 3: More Testing in Progress
So, what happens to this rock if you place hot radioactive waste into it? And what changes in the rock when you dry it out before and during the time of waste emplacement? For that a series of drying-rewetting experiments are being performed in a laboratory. But do you change something in the rock if you carve it out of its setting and bring it to the surface for testing? For one thing the pressure is relieved, so as soon as it is bored out of the wall it is placed in sealed pressurzed tubes like these to keep it as intact as possible:
Down below there is a test that subjects the rock to temperatures to be imposed by heat-emitting waste. This screen shot shows the layout, power applied (watts), temperature (Celcius) and pressure (MegaPascals):
For that time in the very extreme future when there is radioactivity released into the rock, it is necessary to know how it would migrate through the rock. It can only diffuse, there is no flowing water in the rock, so diffusion tests are being carried out:
A number of radioactive elements (radionuclides) that can diffuse are being tested (some of these are short-lived surrogates for their longer-lived cousins in the waste, but the range of chemical-diffusional properties covered allows predictions for other isotopes of interest):
The walls where there is injection of these radionuclides and sampling tubes at several distances from the injection points is heavily instrumented in several locations, but this is the main area of diffusion tests:
And here is a data collection system for the diffusion tests:
This rock is not fractured in its natural state, but when you dry it out and relieve pressure on it, it does fracture in response. This fracturing extends for a small distance into the rock and forms what is called the Excavation Damaged Zone or EDZ:
This is even more evident when you excavate a dried out area, it falls to the ground in small fragments:
Experiments are carried out on the EDZ:
Although it seems unlikely that over very long times the EDZ remains a fractured zone, just in case, the design for the emplacement of waste includes putting vertical circular structures in place to interrupt the potential for migration through the EDZ:
There were many more tests, as shown by these instrumented walls involved with various stress-relief (rock movement) tests:
But that is all for this visit. Thanks for being as interested as I was. The only thing left to see on the next page is the countryside in which this laboratory is set, in the rain, in the dusk, and in a moving car.
Go for a ride from the research site into the surrounding area in rain, dusk, and a moving car
Go back to second Bure underground research laboratory visit page
Go back to first Bure underground research laboratory visit page
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