4. Graphite and C/C waste management

Graphite waste management has been the subject of study for many years. Given the large quantities of graphite involved (on the order of 700 tonnes at startup of a prismatic block HTR reactor, or a cumulative total of around 6,000 tonnes of graphite at the end of the reactor's life, including replaced elements), it is important to minimize as far as possible the content of impurities in graphite that can activate under neutron flux. This limits the graphite's radiological inventory and makes it easier to manage the reactor dismantling and waste storage phases.

The main radionuclides identified in irradiated graphite are ⁶⁰ Co, ¹⁴ C, ³ H, ⁶³ Ni, and ^36...