AES Section Meeting Reports

Pacific Northwest - August 20, 2011

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The PNW Section joined with a reinvigorated Acoustical Society of America (ASA) NW Chapter for a summer field trip to see the acoustical testing facility of NWAA Labs near Satsop, WA. NWAA Labs has some of the largest facilities in the world for testing acoustical materials for such characteristics as sound transmission loss, scattering and diffusion, and devices such as speakers. Interestingly enough, the facility is housed in a never-finished nuclear reactor building, utilizing its huge spaces and stable environment. The site also provides a fascinating side tour of the nuclear plant. The lab is about 100 miles southwest of Seattle, and attendees were given the option of driving themselves, or paying $25 for a passenger van ride, subsidized by ASA funding. Six AES members were accompanied by about 17 ASA affiliates or guests for this all-day event, held Saturday, August 20, 2011.

Ron Sauro is the owner/chief scientist for NWAA Labs, a noted EASE acoustical modeling software expert, and former NASA scientist. He figured the massive buildings would make an excellent acoustic test lab. The nuclear power plant was mothballed in the 1980s (3 weeks before the fuel was to be installed) due to financial problems, bad power demand forecasts, and public disenchantment. By the 1990s, it was declared a failure, the public bonds were defaulted on, and the property was returned to the community. A few industrial tenants rent space in what is now the Satsop Development Park.

With Ron's wife Bonnie, our group started right off by inspecting the nearly complete nuclear reactor vessel and containment building, since you have to go by it to get to the lab. The group viewed reactor support structures, such as the emergency water cooling tanks and spent fuel processing pools (all empty). Ron envisions turning some of the spaces into such uses as a huge anechoic chamber, or a pool for testing submarine ROVs. The acoustical lab has been retrofitted inside the more normal, but still massive, control and support rooms for the reactor. The elevator was out of service this day, so a lot of walking and stairs through the huge plant was the order of the day.

The main acoustic test rooms are large adjacent reverberant rooms, with a 10.5 by 12.5 foot cutout between them used to test transmission loss of products. One room is stimulated with noise, the other room holds the measurement microphones. Transmission loss thru the barrier requires extreme levels in the source room in order that the levels measured in the receive room are sufficiently above the noise floor of the measuring microphones. Since the concrete interior walls are between 3-5 feet thick, leakage through the wall structure is not an issue. Scattering, diffusion and absorption of materials is also tested here, aided by a large turntable. The massive structure and stable environment allow accurate testing to very low frequencies, while conforming to test standards.

The group took a lunch break by driving to the nearby town of Elma, although attendees were free to have their own picnic at the reactor. After returning, the tour continued in the labs, where Ron showed the turntable mechanics in the space beneath the test room, and demonstrated some high level noise in the sending room, and how it is analyzed in the receiving room.

The tour next went to the speaker testing area, which is housed is what was to have been the steam turbine electric generator room. The lab only uses a small area of the 600 foot long building, where it uses a computerized test rig, a circular arc truss with measurement mics, and a turntable. During the day, a manufacturer of industrial storage tanks uses the space, taking advantage of the 250 ton cranes.

For an acoustic dessert, we were taken to one of the two water cooling towers to sample the interior sound effects. Pipes in the towers would normally spray hot water up into the tower, where natural air convection currents would cool the water as it falls to the pool at the bottom. Ron is proposing that the large pipe meant for water flow can be used for a large acoustic impedance tube. The tower we visited was not finished with the water plumbing and had fill dirt at the bottom. At 600 feet high with an open top and curved sides, the natural acoustics inside are very unusual and a great source of amusement, as well as being strangely beautiful in the natural light.

To view more photos of this reactor, go to:

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