German technology company SCHOTT announced it has received official permission from the Chinese government to supply glass-to-metal sealed electrical penetration assemblies (EPA) to the country’s civil nuclear facilities.
China’s National Nuclear Safety Administration has awarded the HAF 604 certification for SCHOTT’s EPAs, qualifying the company to supply these to China’s nuclear industry. Nuclear reactors are housed in a completely sealed-off containment structure. However, electrical and instrumentation cables are needed to pass through this structure to provide power, control signals and monitoring for the reactor. EPAs provide the pass-through for such cables while maintaining the pressure boundary integrity of the containment structure. SCHOTT uses glass-to-metal sealing (GTMS) technology in its EPAs. Glass-to-metal seals are extremely durable and highly resistant to deterioration. Conventional epoxy sealing on the other hand, being organic, could degenerate over time and weaken with continuous radiation and thermal shock. GTMS technology uses the principle of compressive sealing, hence, SCHOTT’s EPAs are resistant to extreme shock and could maintain hermeticity, even during loss-of-coolant accidents (LOCA).
SCHOTT’s GTMS products are rigorously tested to withstand high current, voltage, pressure and corrosion. Flame test results also show that the hermetic seals can withstand high temperature loads and are non-combustible even at 750ºC for 4 hours. The EPAs are manufactured according to ASME NQA-1 and are compliant with IEEE317.
As EPAs provide the sealed conduit through the containment wall, the reliability of this product has a direct impact on the safety level of the nuclear power plant.
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