Rigorous Evaluation of Biological Dose for Fusion Systems and Comparison with Approximate Contact Dose Approach

Every few years, maintenance will be required to replace the plasma facing components of any fusion power plant. To come up with a realistic maintenance scheme, an accurate method of evaluating the biological dose rate is needed. In some studies, the simple and quick approach of the contact dose rate for a specific component was used to estimate the biological dose rate. This method doesn't take radiation from nearby components into account and the accuracy of its methodology is questionable. The more accurate multi-step method, which involves transporting the delayed gammas from induced activation in the forward or adjoint mode, is able to take radiation from all surrounding components into account. In this report, the biological dose rate was evaluated with the adjoint method at selected radial locations of ARIES-CS, and then compared to the contact dose rate of the nearest component to determine the accuracy of the contact dose method. Our results indicate that the approximate contact dose rate could be off by an order of magnitude.