ASME N509 pdf download NUCLEAR POWERPLANT AIR-CLEANING UNITS AND COMPONENTS
1 SCOPE This Standard covers requirements for the design, construction, and qualification and acceptance testing of the air-cleaning units and components which make up Engineered Safety Feature (ESF) and other high effi- ciency air and gas treatment systems used in nuclear power plants.
1.1 Limitations The Standard does not cover sizing of a complete nuclear air treatment system, redundancy, or single-fail- ure requirements. It applies only to systems which employ particulate filtration, ambient-temperature adsorption, or both, as the principal functional mecha- nism. It does not apply to condenser off-gas systems. Also, it does not apply to other applications that employ primarily gas storage or holdup, cryogenic adsorption or fractionation, or solvent absorption as the principal method of gas treatment. Nor does the Standard cover requirements for containment isolation valves, recom- biners, comfort heating, air-conditioning, or ventilation to achieve ordinary cooling or industrial hygiene objec- tives. Field acceptance testing of nuclear air-treatment systems is covered in ASME AG-1, Section TA (the pri- mary reference was to ASME N510-1989).
1.2 Purpose The Standard identifies and establishes requirements for filters, adsorbers, moisture separators, air heaters, filter housings, dampers, valves, fans, ducts, and other components of nuclear air-treatment systems for a spe- cific application in a nuclear power plant. The Standard also establishes requirements for operability, maintainability, and testability ofsystems necessary for the main- tenance of system reliability for the design conditions. Qualificationand acceptancetestingprovisions are spec- ified to verify the adequacy of the air-cleaning unit and component design, to verify that components have been properly fabricated and installed, and that the system will perform in accordance with specification require- ments.
2 APPLICABLE DOCUMENTS The following documents supplement this Standard and are a part of it to the extent indicated in the text. The issue of the referenced document noted below shall be in effect. If no date is listed, then the issue of the referenced document in effect at the time ofthe Purchase Order shall apply.
3 TERMS AND DEFINITIONS Terms and Definitions are located in ASME AG-1, Article AA-1000 and various specific ASME AG-1 Code sections.
4 FUNCTIONAL DESIGN
4.1 General Depending on the function of the system and the conditions under whichitwilloperate, air-cleaningunits include some orallofthe followinginternalcomponents. (a) Prefilters are required in air-cleaning units when design inlet particulate concentrations and particle size are suchthatthe HEPA filter may be rendered ineffective prematurely. On other air-cleaning units prefilters are recommended only when it is desired to increase HEPA filter life.