Elastomer Technology

Shieldseal 663 - Radiation grade

A specially developed peroxide cured ethylene-propylene terpolymer for the manufacture of moulded components, such as O-rings, that will be subjected to ionising radiation.

This PMUC approved material has been subjected to extensive gamma radiation/thermal ageing testing to replicate a 40-year lifespan in active areas of a nuclear power plant.

Typical applications
Moulded seals and other components, where a long service life is needed for duties where ionising radiation is present.

It is particularly suited to applications involving air, hot water and steam. This, together with its suitability for contact with a wide range of media including dilute acids and alkalis, ketones, lower alcohols, and silicone oils and greases, makes it suitable for use in processes associated with nuclear waste.

Standards and approvals
Shieldseal 663 is PMUC approved (certificate 17-0383) for use in French nuclear plant. 

Specification testing
Evaluated for resistance to ionising radiation by monitoring changes in important physical properties over time while irradiated with gamma radiation.

The results of radiation/thermal testing, carried out in accordance with international standards, show that Shieldseal® 663 has excellent long-term radiation resistance up to a dose of 1600kGray in radiation conditions that include elevated temperatures up to 70°C. Thermal pre-ageing of the samples did not significantly alter the end-of-life ageing characteristics.

Further information on these tests as carried out by an independent test house and James Walker Technology Centre can be supplied upon request.

Special features

  • Excellent long-term resistance to ionising radiation
  • Strong resistance to short-term high pressure and temperature spikes encountered in accidental conditions in nuclear power plants
  • Very low levels of ions such as Cl- and SO42- that can leach from materials to promote metalwork corrosion within a nuclear reactor

Operational properties of Shieldseal 663
Temperature capability: -47°C (at atmospheric pressure) to +125°C constant, or +150°C intermittent
Hardness (nominal): 80 IRHD
Tensile strength: 18MPa
Modulus at 50% elongation: 3.4MPa
Modulus at 100% elongation: 7.9MPa
Elongation at break: 198%

Compression set: 70 hours at 125°C: 10.5%
Compression set: 70 hours at 200°C: 31.8%
Compression set: 24 hours at 300°C: 63.4%
Compression set: 70 hours at 300°C: 89.0%

Air ageing, 70 hours at 125°C
Change in hardness: +1 IRHD
Change in tensile strength: -11%
Change in elongation at break: -22%

Fluid immersion testing, deionised water, 70 hours at 180°C
Change in hardness: -6 IRHD
Change in tensile strength: -7%
Change in elongation at break: +6%
Change in volume: +1.8%

Water soluble sulphate content: <3ppm (result below 3ppm limit of quantitation)
Water soluble chloride content: <3ppm (result below 3ppm limit of quantitation)

(Typical values quoted: Please consult James Walker before using for specification purposes)

How supplied
Shieldseal 663 is available as precision moulded components. We are also willing to partner with equipment manufacturers and end-users to develop, prototype and evaluate materials or specific components for custom applications.

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