Canadian Consulting Engineer

TRIUMF Advanced Rare IsototopE Laboratory

December 1, 2014
By Mechanical engineer: Stantec

A recently completed building on the TRIUMF campus near Point Grey in Vancouver houses the Advanced Rare IsotopE Laboratory (ARIEL). TRIUMF is Canada’s national laboratory for particle and nuclear physics. It has over 350 scientists,...

A recently completed building on the TRIUMF campus near Point Grey in Vancouver houses the Advanced Rare IsotopE Laboratory (ARIEL). TRIUMF is Canada’s national laboratory for particle and nuclear physics. It has over 350 scientists, engineers and staff, besides 150 students, performing research on the campus.

The new ARIEL building, nestled between existing facilities, is completed, but the scientific equipment is still being assembled and won’t be fully operational until 2018. ARIEL will house a made-in-Canada, high-power superconducting electron accelerator that will produce exotic isotopes for science, medicine and business. The building is integrated with facilities at TRIUMF so that it can use a future proton beam from the existing cyclotron. By adding the lighter electron particle beam, the range of isotopes that can be produced at the site will be greatly expanded.

The unique facility will house and service the following major scientific installations:

• Electron linear accelerator

• Specialized proton beam line

• High-power target stations

• Front end and isotope separator

• Ancillary laboratories, assembly laboratories for target handling, decay storage, laser technology lab, etc.

The building has six levels, including two levels below ground, and a shared mechanical and electrical room at the upper level. It is a registered Class 2 Nuclear Facility, designed according to Canadian Nuclear Safety Commission guidelines and safety standards, as well as the NFPA 801 Standard for Fire Protection for Facilities Handling Radioactive Materials. It is also designed for LEED certification, which is an achievement given this is an energy-intensive building.

The design team collaborated extensively with the researchers and physicists who will use the facility. Prime consultant Chernoff Thompson Architects coordinated the three branches of engineering. Structural engineering was by Bush, Bohlman & Partners, electrical engineering was by AES, and mechanical engineering was by Stantec.

The depth of the construction adjacent to existing buildings, and the massive walls, which are a part of the radiation shielding strategy, created particular challenges. The ductwork, pipe and cable placement, for example, needed to be carefully worked into the design during the early stages. Three-dimensional models helped with this process. As well, the scientific equipment and services required precise construction with tight tolerances, and needed good coordination within the construction team.

Mechanical systems – controls and redundancies

All the building services have multiple functions. They have to serve the equipment and the process, but also to provide safety to the occupants and the public under different operating conditions: normal, high radioactivity, fire mode, etc.

The operating parameters of the systems are set to complement each other and are coordinated through two purposely-separated control systems. The primary control system looks after all safety and life safety aspects of the operation and is continuously monitored from an operations room. The secondary control system looks after comfort, temperature control and less critical aspects of operation.

 Incremental pressurization

Incremental pressurization is the backbone of safety in the facility.

The air exhaust system, classified as the “nuclear ventilation” system, operates continuously and serves all areas. It ensures incremental pressurization for areas with higher hazard and potential for contamination. The exhaust system provides HEPA and, where necessary, carbon filtration of the exhausted air. The air is discharged using high plume dilution fans. Safety features include continuous monitoring and a shutdown in an emergency when the exhaust would be stopped and the building would be evacuated and sealed for assessment.

The building’s supply air VAV system tracks the exhaust and complements the space pressurization strategies. The supply air-handling unit uses a dual air stream concept. Each stream includes a fan array (“fanwall” concept) and if one array is being maintained or repaired, the other can independently support the building operation. The two air streams work in parallel under normal conditions, reducing the total fan power consumption.

Cooling strategies

The electron beam is accelerated by a linear accelerator cooled to liquid helium temperatures (2K to 4K, or -271C to -269C). This specialized cooling is provided by a helium cooling loop, and helium system compressors located in an adjacent building. Portions of this stainless steel helium system piping were part of the ARIEL building design team’s project.

The mechanical cooling system uses water circulation loops which serve to cool the building, but also to cool the electrical equipment (“low active system”), and areas or equipment with radioactive activation potential (“high active system”). Both process cooling loops use highly aggressive de-ionized, low conductivity water, which requires stainless steel piping. The process will use close to 2 MW of power, which requires cooling.

The process cooling is connected to the TRIUMF site’s central cooling tower farm, using multistage pumps in ARIEL’s basement. This strategy allows all condenser water from the ARIEL building, as well as heat rejected in other components of the TRIUMF site, to be available at a single point. From here it could provide a proportion of heat to a UBC-wide district heating network. The heat recovery system and associated plant is currently under consideration by UBC plant operations.

Heating and cooling for the building are provided by heat recovery chillers in a heat pump configuration. They can recover heat within the HVAC system, and can also recover heat from the process cooling before the water is directed to the cooling towers. The chillers are of a modular concept, which enables a phased build-out, good control under partial load, and good redundancy characteristics. In the absence of the process load, the building heating is also supported by redundant condensing gas-fired boilers.

Varying demands for air
flow and temperature

The laboratories, which include radioactive (“hot”) and “cold” labs, have occupied and unoccupied set modes for air flow and room temperature. Some areas have very different minimum requirements under different modes of operation. In all cases, these modes are programmed for energy conservation. A good example is the target hall, which is a large volume area used to crane the spent radioactive targets into the hot cells for further handling, The hall has high air-flow requirements and higher pressurization requirements only during brief periods of the target transport. For the majority of the time more economical operating parameters satisfy the hall’s needs.

Drainage and fire protection

The drainage system in the building incorporates “active” sumps in the basement, which are emptied manually after the water is assessed safe for discharge. Holding tanks are designed to include water from accidental hazard levels in the process cooling systems, or to hold the discharge of sprinklers in a fire. In each case, the water is assessed and only discharged when confirmed safe. The fire protection system includes a pre-action system so staff can take action on a false alarm and minimize the potential for leaks or water damage.

The building, which was completed in July 2013 on time and on budget, won an award of merit in the 2014 ACEC-BC Awards for Engineering Excellence. cce


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