System Testing and Control - STD-1128-98master0330

DOE-STD-1128-98

Guide of Good Practices for Occupational Radiological Protection in Plutonium Facilities

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 accident conditions. These requirements should include

system and component design characteristics, such as the installation of standby

spare units, provision of emergency power for fans, installation of tornado

dampers, seismic qualification of filter units, and fail-safe valve positioners.

The ventilation system should be designed to operate effectively and to permit

servicing or filter replacement while operating. The system's effectiveness should

be assessable during operation by means of installed testing and measurement

devices.

Air-cleaning systems should be designed for the convenient, repetitive, and reliable

in-place testing of each stage of the system for which credit is taken in accordance

with ANSI/ASME N510-1989, Testing of Nuclear Air Cleaning Systems (ANSI,

1989d). Provisions for in-place testing should include aerosol injection ports,

sampling ports, and connecting and bypass ductwork. Each filter bank should be

tested upon installation, periodically thereafter, and anytime when conditions have

developed that may have damaged the filter, e.g., pressure drop, over-pressure,

water spray, etc. The filter or filter bank should be tested and demonstrate a

particle-removal efficiency as described in ANSI/ASME N510-1989, Testing of

Nuclear Air Treatment Systems (ANSI, 1989d), and ANSI/UL 586-1990, High-

Efficiency Particulate Air Filter Units (ANSI, 1990).

The portions of the ventilation system that are essential to preventing releases of

radioactive materials should continue to function (or automatically change to a

safe-failure mode) under abnormal or accident conditions. The ventilation system

fans should produce a maximum exhaust rate that is greater than the maximum

supply rate. Exhaust fans should be provided with emergency power in the event

of loss of normal electrical power supplies. Exhaust and supply fans should be

redundant. If the system fails, exhaust-control dampers should fail in the open

position and the supply-control dampers should fail in their preset closed position.

Supply fans should automatically cut off when the exhaust-fan capacity in service

is not sufficient to maintain the proper pressure differential. Alarms should be

provided to signal the loss of fan capacity or improper air balance. System

components or devices that must function under emergency conditions should be

able to be tested periodically, preferably without interruption of operations.

Appropriate surveillance instrumentation and manual system operation controls

should be provided at one common location. In addition, surveillance

instrumentation should be located in an external or protected area that would be

accessible during and after all types of postulated accidents.

C-24