System Testing and Control - doe-std-1128-98

DOE-STD-1128-98

The filtration system should be designed to allow for reliable in-place

testing of the HEPA filters and ease of filter replacement to the extent

practicable.

The exhaust system for a glove box or hood should be separate from the

exhaust system for room air. The hood exhaust system need not be

separate from room exhaust ventilation if ventilation is once-through.

Exhaust air should be drawn through a HEPA filter at the glove-box or

hood-exhaust point to maintain primary control at that point and

minimize contamination of ductwork. This filter should not be counted

as a confinement barrier unless it is testable in place. Additional HEPA

filters in series should be separated at a sufficient distance to permit in-

place testing of each stage of the filters.

Dampers should be installed in the glove-box, hood, and room-exhaust

ducts so that required air-pressure differentials can be maintained.

Automatic backflow dampers should be installed in series with the

exhaust dampers. Manual controls, or automatic controls with manual

override, should be provided as needed for ventilation systems or their

components for flexibility of operation.

Integral fire-suppression equipment should be provided as needed within

each ventilation system to ensure that a safety-basis fire could not

degrade the integrity of the high-efficiency air cleaning system. Where

appropriate, a cool-down chamber with water sprinklers, a pre-filter

demister, and a spark arrestor screen should precede the first stage of the

final HEPA filtration system. The water spray from a cool-down

chamber should be automatically actuated by appropriate temperature-

and smoke-sensing devices as determined by the accident analysis.

All potentially contaminated air should be exhausted through a common

stack. Continuous monitoring and a representative, redundant sampling

capability should be provided on exhaust stacks that may contain

radioactive or toxic materials. The ventilation exhaust stack should be

located as far away from any air intake as is reasonably possible. Design

criteria for effluent monitoring and sampling and elements for

consideration in effluent radioactivity measurement are described in

DOE/EH-0173T, Environmental Regulatory Guide for Radiological

Effluent Monitoring and Environmental Surveillance (DOE, 1983).

ANSI N42.18 provides specifications and performance of onsite

instrumentation for continuously monitoring radioactivity in effluent

(ANSI, 1974a).

C.5.1.5

System Testing and Control

The ventilation system is considered an essential safety and control

system and should be designed in accordance with ANSI/ASME N509-

1989, Nuclear Power Plant Air Cleaning Units and Components (ANSI,

1989b). The minimum acceptable response requirements for the

ventilation system, its components, instruments, and controls, should be

established based on results of safety analyses for normal, abnormal, and

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