The sealing performance requirements of tungsten alloy shielding containers constitutes the core capability for achieving physical containment of radioactive material and zero aerosol release, directly affecting operator dose, environmental contamination risk, and regulatory compliance. Sealing must remain reliable under static, dynamic, and accident conditions, encompassing molecular-level barrier function and long-term aging stability.
Static sealing demands that the container maintain very low leakage rates across normal to maximum service temperature, cumulative irradiation, and minor internal pressure variation, typically achieved through multi-step hard-metal labyrinth combined with elastic sealing rings. The labyrinth steps provide geometric blocking and multiple redirection paths, while elastic rings compensate for minor deformation and thermal expansion/contraction, ensuring no detectable leakage during prolonged stationary storage. Dynamic sealing addresses frequent opening/closing scenarios, requiring sealing surfaces to retain initial fit precision and elastic recovery after tens of thousands of manipulator or manual operations, with surfaces possessing sufficient hardness and low friction to resist wear.
Accident-condition sealing requires maintenance of basic containment following drop, fire-induced high temperature, or external impact, with the metal labyrinth serving as the final defense line when elastic rings fail. Sealing material selection must balance irradiation resistance, high-temperature tolerance, strong oxidizing decontaminant resistance, and low outgassing characteristics, commonly employing fluororubber, metal C-rings, or bellows structures.
Sealing performance is verified through vacuum leak testing, pressure decay methods, and helium mass spectrometry at progressive stages, undergoing accelerated aging and post-irradiation re-testing in type approval. Qualified sealing design enables tungsten alloy shielding containers to achieve reliable radioactive material containment in nuclear medicine hot cells, isotope production, and waste storage applications.
