Shieldseal® 663 is the latest elastomer developed by James Walker for long-term applications in ionising radiation, as experienced in nuclear power plants, and nuclear waste transportation and storage facilities.
Based on an ethylene-propylene terpolymer (EPDM), Shieldseal 663 is a specially formulated material of 80 IRHD that can offer a service life of 40+ years in ionising radiation as a fluid seal or elastomeric component. In a power plant it will work efficiently in contact with air, water, or steam at up to 150°C constant.
It is also recommended for long-term contact with a variety of media associated with nuclear waste, such as dilute acids and alkalis, ketones, lower alcohols and silicone oils and greases.
One of its main benefits is it contains very low levels of the sulphate and chloride ions that can contribute to corrosion in metalwork. The levels are less than 3ppm, the exact figure being below the measuring capability of the laboratory equipment used.
Shieldseal 663 has been subjected to rigorous environmental qualification (EQ), at AMEC’s Cobalt-60 facility, to demonstrate that it can function efficiently as a fluid sealing material throughout the 40-year working life of a nuclear plant.
International standards IEEE 383 and IEC 60780, and the French standard RCC-E, were used as bench marks for the thermal and radiation ageing investigations.
Radiation dosages up to 1000kGy were applied to the material at 23°C and 70°C to simulate normal long-term usage in a nuclear plant. A further 600kGy was applied to simulate additional radiation that could result from a loss of coolant accident at a plant.
The results show that the material’s end-of-life conditions, for both elongation at break and compression set, were both reached at 1600kGy. Thermal pre-ageing of the samples did not significantly alter the end-of-life ageing characteristics.
The Institut Laue ,Langevin international research centre (pictured) which operates at the leading edge of neutron science and technology is one of the first sites to use components manufactured in the new James Walker Shieldseal 663 material.