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Active Handling Experiment with Neutron Sources

Objective

The objective of the AHE experiment is to investigate radiological aspects of handling high-level waste (either spent fuel or vitrified high level waste) in an underground repository. Neutron dose rates are measured resulting from direct radiation and from neutrons scattered by the surrounding host rock (rock salt). Computer codes and model calculations are to be verified by these experiments. Thus, an experimentally validated tool will be available for future detailed repository planning with emphasis on minimizing the radiation exposure of the operating personnel.
The project was a demostration test which was reformed by DBE and ANDRA/CEA in the Asse mine. The objective of this experiment was to investigate radiological aspects of handling spent fuel/high level waste in the drifts of an underground repository in a salt dome. As neutrons play an important role in the direct disposal option, main emphasis was laid on their contribution to total dose rate. Due to the narrow drift dimensions, backscattering of the neutrons from the drift walls had to be expected, thus increasing the dose rate for the operating personnel.

The experimental results showed that the intensity od neutron backscattering from the drift walls depends upon the drift cross section and the position of the cask within the drift. The equivalent dose rate in the near-field of the cask during underground handling was two to three times higher that above ground. Predictions performed with the Monte Carlo programmes MORSE, MCNP and TRIPOLI were in excellent agreement with the experimental findings. Thus, validated computer codes are available for future detailed repository planning with emphasis on minimising radiation exposure of the operating personnel.
Work programme:

Design planning 1991/1992
Implementation planning 1992
Construction and acquisition 1992/1993
Execution and disposal 1993/1994
Evaluation and description 1994

From a more practical point of view, the programme can be broken down into the following activities:

1. Shielding and backscattering calculations for a POLLUX cask with spent fuel and a transfer cask with vitrified high level waste
2. Design and construction of shielding casks which simulate a POLLUX cask and a transfer cask
3. Planning of test programme with shielding casks
4. Planning and design of instrumentation for experiment
5. Execution of the measurements
5.1 Above-ground measurements
5.2 Underground measurements in the Asse mine
6. Evaluation and documentation of the results.

Call for proposal

Data not available

Coordinator

Forschungszentrum Karlsruhe Technik und Umwelt GmbH
EU contribution
No data
Address
Weberstraße 5
76133 Karlsruhe
Germany

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Total cost
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Participants (2)