Contents
Strategy
1. Objectives of the MTR Project
2. Project Programme Phases
3. Graphite Properties and Testing
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1. Objectives of the MTR Project
This business objectives for the MTR project are that the experiment must:
extend the graphite material property database into the region for future AGR operations
improve the understanding of graphite behaviour with combined oxidisation and irradiation, and potential moderating factors, e.g. creep
produce results that are translatable to the AGR operational environment
overlap with existing data to provide a cross-check and experiment validation
2. Project Programme Phases
The MTR project provides graphite material property data on samples subjected to a range of and combination conditions (irradiation, oxidation, and stress loading).
The programme is split into four key phases:
Experience from recent BNG Magnox MTR suggests that existing measuring techniques may fail at elevated weight loss. It is imperative that measuring techniques are validated prior to commencement of irradiation to gain confidence that meaningful measurements can be taken during the post irradiation examination. This element of work will explore the limits of existing techniques and sample geometry, and develop new techniques where necessary for the overall MTR programme.
This experiment is required to extend the current material property database to bound future AGR operations with elevated weight loss. This is the simplest experiment and is a continuation of previous work.
To improve predication of future graphite degradation it is necessary to determine creep behaviour for graphite subject to both irradiation and oxidation. A compressive creep experiment is the optimum method to accumulate a data set to describe a creep behaviour trend. This experiment is relatively more complex than the unstressed experiment and design of the loading mechanism is critical to ensure loading control during the experiment. Nevertheless, the compressive creep experiment is a development of previous programmes
Tensile creep experiments are significantly more complex for the control of thermal hydraulics, and are very expensive in terms of cost per sample irradiated. However, it may be necessary to complete a small tensile creep experiment to fully underwrite a creep model.
3. Graphite Properties and Testing
Trepanned graphite samples are artificially aged within the high flux reactor and then undergo experimentation. Subsets of data from the MTR experiments have been fitted to give a series of graphite property models.
The property measurements undertaken on the trepanned samples may include:
