Instrumentation and Control Systems

DOE-HDBK-6004-99

information including variability using response spectra or time history. For large embedded

structures, soil structure analysis may be considered.

Capacity calculations, DOE 1994a, depend primarily on the national consensus code, UBC 94. For

reinforced concrete structures DOE 1984 and ACI 318 provide the criteria for safety-class and other

building structures, respectively. For steel structures AISC Codes, ANSI 84 and AISC 86a provide

the criteria for safety-class and other building structures. AISC 86b is an alternate for AISC 86a if

load and resistance factor design procedure is used. ASME Code (ASME 93a) should be used for

equipment and components, and ASME Code (ASME 93b) for piping.

Deformation may be allowed and inelastic energy absorption credited for ductile structural materials,

especially for lower performance categories. Inelastic absorption capacity should not be credited if

concrete is used as a pressure boundary.

For lower performance categories, and for normal operations, damage may be permitted but should

be limited so that hazardous materials can be controlled and confined, occupants are protected, and

safety functions are maintained.

For the higher performance categories, and for unlikely events, structures should be permitted to

undergo limited inelastic deformations. Energy absorption factors may be used to achieve appropriate

conservatism in the design or evaluation process. Stability and other post yield behavior criteria

should be met.

For extremely unlikely events risk analysis should be performed to determine the extent of permissible

damage.

INSTRUMENTATION AND CONTROL SYSTEMS

Instrumentation and Control (I&C) systems include equipment and components that monitor and

display facility parameters, indicate parameter value changes, actuate equipment to maintain the

parameters within specified limits, return the facility to operation within these limits, and mitigate

conditions resulting from operation outside limits. Specific equipment includes sensors, signal

transfer media, signal processors, control circuits and actuation devices.

General Safety Design Guidance

The purpose of this section is to present the principal design criteria for the Instrumentation and

Control (I&C)Instrumentation and Control systems and components. The I&C system design should

be separated into the basic control system and the safety system. The separation of these I&C system

functions is necessary to ensure that once a safety system is called upon the control function will not

stop or impede the proper safety system function execution. Conversely, the safety system must not

interfere with the operation of the control function, when the facility or system is operating within

the normal design envelope. The basic control and the safety systems analysis and design should

ensure independence of system functions and displays with sufficient analytical margin, physical

separation, and electrical isolation to enable each system to support the others function without

interference under failure, accident, or normal operating conditions. To ensure that these basic

principles are properly addressed, the I&C analysis and design efforts must be properly integrated

between control and safety system design and with the design and analysis of the facility systems (FS)

they are intended to service.