HVAC System - h3010v20153

DOE-HDBK-3010-94

Appendix B; Plutonium Recovery Facility

2.1.3.4 H V A C S ystem

The ventilation system, which is depicted in Figure B.4, consists of two independent once-

through airflow systems, a recirculating nitrogen system for the metal reducing line, and a

vessel vent system that ties back into the main building exhaust. All exhaust goes through

High Efficiency Air Particulate (HEPA) filters before entering an underground tunnel where

it is joined by exhaust from other nearby facilities and exits from the H Plant stack.

There are six ventilation supply fans for the building. These centrifugal fans operate in sets

of two, with one always serving as an automatic start standby fan in the event of failure of

the running fan. Two of the fans serve the "clean" areas (System A) (i.e., general access)

and four of the fans serve the production areas (Systems B and C). The "clean" areas are

designed to have 8 air changes per hour, while the production areas are designed to have 14

air changes per hour. The system is designed to keep the temperature at 75 F and 50%

humidity in the summer, 70 F in the winter, and to keep all glovebox temperatures below a

maximum of 100 F.

All supply air is prefiltered, filtered, and heated or cooled as appropriate before entry into

the building environment. Fail-shut, tornado-proof supply air dampers are provided at each

inlet as well. All glovebox ductwork in the building is constructed of galvanized steel

piping.

System A sends all of its exhaust through plenum A, which has two HEPA filter banks in

series. It is basically a straight through system. System B has three main branches. The

first consists of supplied air serving corridors and various areas that are not expected to be

routinely contaminated. This branch, like System A, moves straight through the building to

Plenum B where there are four HEPA filter banks in series. The second branch is glovebox

airflow for the feed preparation glovebox, the dissolving line, the sample glovebox, and the

wet processing line. Air entering the associated maintenance rooms is admitted into these

gloveboxes through glovebox-mounted HEPA filters. It exhausts through glovebox mounted

HEPA filter units as well, and joins up with exhaust air from the third branch discussed

below before entering Plenum C.

An additional set of supply fans divert a portion of this airflow through an air dryer to the

calcination and hydrofluorination lines, which are considered System C. The air drying

system includes a multi-stage dehumidifier to produce 68 F air with a dewpoint of -40 F.

This low moisture content is necessary to produce an acceptable product. These calcination

and hydrofluorination gloveboxes have piped-in supply air headers, but inlet air still passes

through a glovebox-mounted HEPA filter. This air is exhausted through glovebox mounted

HEPA filters and progresses to Filter Plenum C.

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