Filter Plenum Construction

DOE-STD-1066-99

14.1.2 Although the guidelines in this section are specifically applicable when only high

efficiency particulate air (HEPA) type filters serve as the final means of effluent

cleaning in a nuclear air cleaning ventilation system, the guidelines can be applied

with engineering discretion to other types of filtration and cleaning systems and their

configurations.

14.1.3 This section does not include specific definitive fire protection design requirements

for High Efficiency Metal Fiber filter systems, Radioiodine Adsorber air cleaning

systems, Deep Bed Fiberglass filter systems, or Deep Bed Sand Filter systems (See

ASME AG-1-1994, "Code on Nuclear Air and Gas Treatment" for definitions. Refer

also to Appendix A). This section does not include the protection of HEPA type filters

utilized in a clean room application. (Refer to NFPA 318.)

14.2 Filter Plenum Construction

14.2.1 HEPA Filters

All HEPA filters used in nuclear ventilation exhaust systems should meet the requirements for

HEPA filters in ASME AG-1, Section FC, and be listed as a High Efficiency Particulate Air

Filter Unit as tested in accordance with UL 586. (Note: For operating temperatures of HEPA

filters, see Appendix B).

14.2.2 Duct Entrance and Prefilters

All nuclear duct entrance filters and prefilters located upstream or made part of final HEPA

filter exhaust plenums should be listed as Class 1 Air Filters unit as tested in accordance with

UL 900.

14.2.3 Filter Framing

Filter framing systems may be constructed of combustible material provided that the material

has a flame spread rating of 25 or less and smoke developed rating of 50 or less.

14.2.4 Number of Final HEPA Filters

When nuclear HEPA filters serve as the final means of effluent cleaning, a minimum of two

stages of HEPA filters should be arranged in series in the final filter plenum. In existing HEPA

installations, one of the two stages of final HEPA filters may be located upstream from the

final filter plenum.

14.3 Location of Final Filter Plenum Ventilation System Equipment

14.3.1 Final Filter Plenums Located Inside Process Buildings

Filter plenums located inside process buildings and other buildings should be separated from

all parts of the building and be enclosed by 2-hour fire-rated construction. Buildings should

be provided with fire protection (i.e., smoke detector, sprinkler systems) for the appropriate

particular hazards within the building.