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Tracer Gas Testing...

Increased regulatory skepticism concerning the adequacy of control room habitability analyses has prompted many nuclear utilities to reexamine in detail the assumptions underlying their analyses. The amount of unfiltered air entering the control room envelope is one of the critical assumed quantities. Until recently nuclear utilities could only rely on a variety of engineering models in order to arrive at a value for unfiltered air inleakage. These engineering models were based on crude and often incomplete assumptions about the nature of air flow through indoor spaces.

Research and development activities undertaken over the last twenty years for energy conservation studies and military defense evaluations have produced a technology that uses tracer gas measurements to study the detailed performance of critical ventilation systems. Using this technology it is possible to quantify unfiltered air inleakage into an operating nuclear power plant control room. Recent testing at a number of plants under actual operating conditions using this technology has shown that the engineering models are inaccurate. The magnitude of error based on modeling alone has been shown to be significant.

In order to improve existing habitability analyses, proactive utilities have engaged NCS/LAT to test their control room envelopes for unfiltered air inleakage using tracer gas technology.

Based on the magnitude of the inleakage measured during initial testing, NCS/LAT provides engineering guidance and technical recommendations. Guidance includes the training of repair personnel on retrofit measures and sealing techniques to significantly reduce control room envelope inleakage rates.

Field application of the tracer gas technique in the nuclear power plant environment has demonstrated that unfiltered air inleakage can be both quantified and reduced.

Using a unique tracer gas approach, the complex nuclear airflow and ventilation questions that arise in any control room inleakage assessment can be addressed more quickly, accurately, and economically than by conventional techniques. In most instances a tracer gas technique is the only method that can provide actual operating performance information.

NCS Corporation

NCS Corporation has led the industry since 1968 in the testing and servicing of safety-related HVAC systems. NCS maintains an audited 10CFR Appendix B quality assurance program with test personnel qualified to ANSI N45.2.6, assuring the attention to detail, procedural integrity, and technical excellence demanded by the nuclear power industry.

NCS measurement services include laboratory testing of activated carbon in accordance with ASTM Standard D3803 and leak testing of nuclear air treatment systems in accordance with ANSI/ASME Standard N510.

As a result of a fifteen year association between NCS and LAT, NCS is able to include control room habitability studies and duct leakage measurement to the list of services provided to the nuclear power industry.

NCS also supplies nuclear grade activated carbon and filter testing equipment as well as offering carbon adsorber refilling services.

Lagus Applied Technology

Lagus Applied Technology, Inc. (LAT) provides specialized equipment and measurement consulting services for the assessment of general and industrial ventilation system performance and indoor air quality.

Since its inception LAT, in partnership with NCS, has provided tracer gas testing services to assess the habitability and safety of power plant control rooms for numerous utilities within the nuclear power industry.

LAT has performed tracer gas measurement services for companies within the semiconductor industry to investigate ventilation performance and contaminant migration patterns in existing chip fabrication facilities

LAT routinely performs exhaust reentrainment studies using tracer gas techniques for companies within the chemical and pharmaceutical industries to evaluate the safety of existing and planned exhaust systems.

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