[singlepic id=436 w=120 h=80 float=right]Beryllium High Heat Flux Testing at PMTF
Because the high-pressure/high-temperature (HPHT) coolant loop at the PMTF can control inlet temperatures to the sample while maintaining high working pressures, it is an ideal choice for the fatigue testing of beryllium components. Inlet temperatures as high as 280 °C can easily be maintained. The entire PMTF is a Sandia/DOE environment, safety, and health (ES&H) approved beryllium handling facility. The building is equipped with special ventilation ducts and a HEPA filter system, which permit high-temperature water testing of beryllium-armored components in both the EB-60 and EB-1200.
Our beryllium campaigns are currently aimed at applications for fusion energy in which power densities of 0.5–2.0 MW/m2 over a 74 cm heated length, as are anticipated for ITER, can easily be applied for 102 cycles with 30-second durations. Using the HPHT loop, surface temperatures of beryllium between shots can be maintained above 150 °C, which is necessary to maintain beryllium above its ductile-to-brittle transition temperature.
The EB-1200 has been equipped with a portable negative pressure room at the door to the D-shaped vacuum chamber. This “gray” room is equipped with a HEPA filtration system and is maintained at a negative pressure anytime that beryllium is outside the vacuum chamber. The “gray” room prevents the potential spread of beryllium particulate into the EB-1200 high-bay and will be used as a staging area for all EB-1200 beryllium targets. All target instrumentation and coolant connections will be made in the room before installation into the EB-1200 vacuum chamber. The “gray” room is an ES&H requirement for safe beryllium handling during high-heat-flux testing of beryllium-armored mock-ups and beryllium-armored PFC prototypes.
A portable CO2 pellet blast cleaning system (consisting of a pellet hopper, pellet delivery system, controls, and blast gun) is now used for electron beam test system vacuum vessel beryllium decontamination and has shortened the beryllium clean-up procedure from three weeks to one. The CO2 cleaning system is supplied with compressed air at 150 psi and a dual-stage air dryer to remove moisture from the blast air. The chambers are maintained at a negative pressure during cleaning, and the CO2/debris exhaust passes through a beryllium-HEPA system. Glove-box fixtures and custom blast nozzles were fabricated for both the EB-60 and EB-1200. With the CO2 system, workers can perform efficient vacuum chamber decontamination while they remain outside the chambers and, thus, reduce their risk of exposure to beryllium particulate.