ASME N509:2002 pdf download

ASME N509:2002 pdf download.NUCLEAR POWER PLANT 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 ACME AG-1, Section TA (the pri- mary reference was to ACME 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, maintain- ability, and testability of systems necessary for the main- tenance of system reliability for the design conditions. Qualification and acceptance testing provisions 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.
4 FUNCTIONAL DESIGN
4.1 General Depending on the function of the system and the conditions under which it will operate, air-cleaning units include some or all of the following internal components. (u) Prefilters are required in air-cleaning units when design inlet particulate concentrations and particle size are such that the 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. (b) HEPA filters are required in all air-cleaning units when filtration of inlet particulate matter requires a min- imum efficiency of 99.97% for particles equal to 0.3 micrometer in size. (c) Adsorbers are required when air-cleaning units are designed for removal of adsorbable compounds. (d) Moisture separators (demisters) are required when entrained water droplet concentration may be greater than 1 lb (0.45 kg) of water per 1,000 c h (1,700 m3/hr) of airflow. (e) Heaters should be utilized for air-cleaning units with adsorbers when the relative humidity of air to the adsorber exceeds 70% based upon the 1% percentile meteorological conditions (where applicable). For nuclear air-treatment systems which are unaffected by outside air meteorological conditions, heaters should be utilized when an accident would result in an airstream exceeding 70% relative humidity for more than 1 hr. Cf, Postfilters. When adsorbers are used in ESF air- cleaning units, provision shall be made for a postfilter to retain carbon fines. Postfilters should also be consid- ered in non-ESF air-cleaning units discharging into occu- pied spaces where carbon fine carryover is not acceptable.4.4 Environmental Design Condition All parts and components of the air-cleaning unit shall be selected or designed to operate under the environ- mental conditions (temperature, relative humidity, pres- sure, radiation, etc.) specified in para. 4.2. Materials of construction and components shall be selected or treated to limit generation of combustibles and contaminants and to resist corrosion and degradation that would result in loss of function when exposed to the specified envi- ronmental conditions for the design life of the com- ponent. Environmental qualification requirements are con- tained in 10 CFR 50.49, IEEE 323 and ASME AG1, Sec- tion AA and various specific ASME AG-1 Code sections.