Evaluation of tritium transportation to the product hydrogen in the HTGR hydrogen production system

In a high temperature gas cooled reactor (HTGR) coupled with a hydrogen production system, tritium produced at the core contaminate the product hydrogen and the recycle feed water by permeating through the heat exchanger tubes. From the view point of a safety design, tritium concentration in the product hydrogen and the recycle feed water is required to be below as low as reasonably achievable. Reasonable countermeasure for reducing tritium concentration in the product hydrogen is proposed based on the calculation in an HTGR hydrogen production system by steam reforming of natural gas. The proposal is the combination of developed oxide scale and calorized coating on the surface of tubes. Concerning to the necessity of tritium trap system to reduce tritium concentration in the recycle feed water, the calculation results show that concentration level is below allowable limit in the law without tritium trap system Increment of radiation dose for the public is low enough when the product hydrogen is used as alternative energy to fossil fuels.