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The study of radiation damage to the graphite moderator is largely dependent upon the availability of graphite samples from the moderator itself. Because of the varied temperature-flux history and complicated structure of the piles, it is impossible to study the problem from the laboratory standpoint alone. The samples of greatest interest are those taken from the sections of the moderator which have received the greatest damage. However, a comprehensive study requires samples from all sections of the graphite moderator. It is desirable that these samples be solid in order that physical and dimensional measurements of all types may be made. Solid samples enable thermal conductivity measurements and the gradients of damage across tube blocks to be measured. To provide such samples, it was necessary to design some device which would cut solid samples from any location in the pile through the process Channels. The graphite core borer was desigred specifically for this purpose. The objective of this Production Test was to test the operation of the core barer and evaluate the results of its performance.

The power output of the piles is being restricted primarily by three important limitations; those due to graphite temperatures, slug and tube corrosion and maximum power per tube or ``boiling disease.`` The purpose of this document is to present means for increasing very appreciably the ``boiling disease`` limits. In addition, means for alleviating the corrosion limitations will be discussed.