System Testing and Control cont'd - doe-std-1128-98

DOE-STD-1128-98

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.

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