Testing Cell for Gamma Irradiation Tests

Gamma irradiation causes radiolysis in the nuclear power plant core. Although the radical lifetime can be short, they can affect the environment redox potential considerably and consequently modify the oxide films and act as an additional driving force for the construction material cracking phenomena.

Cormet has designed and built two HT HP testing cells to be used under gamma irradiation exposure for the University of Manchester Dalton Cumbria Facility (DCF). An external recirculation loop feeds 350°C temperature and 200 bar pressure water in the heated testing cell located in a lead-walled chamber with a Co-60 gamma source. Water reacts with the specimen and returns to the recirculation loop, where the gaseous radiolysis products are separated from the water flow and led to a mass spectrometer for analysis.

The small testing cell has only an electrically isolated specimen exposed to the HT HP water flow and gamma irradiation in the testing cell. The large testing cell has a working electrode and a counter electrode. The Ag/AgCl reference electrode has been located in the testing cell water inlet line just outside of the gamma chamber. This is not an optimal place for the testing cell but the reference electrode could not be located in the chamber due to the Teflon parts that degrade when exposed to gamma irradiation.

These autoclaves produce valuable information of the material radiolysis in the presence of the gamma irradiated. The installation of the autoclaves and their connection to the recirculation loop required some planning but now the installation can be done in about half day. Unfortunately, the testing cells can be operated with relatively low temperatures because the testing cell isolation material creeps easily.