Instrumentation and Controls

DOE-HDBK-6004-99

embrittlement of the vacuum vessel in the hydrogen environment should be determined by placing

coupons in the vessel to be periodically removed and inspected for embrittlement. An inspection

schedule should be developed and implemented.

Instrumentation and Controls

Instrumentation and controls, where appropriate, should be provided to monitor system parameters

important to the safety function of the vacuum vessel over their anticipated ranges for normal

operation and design basis accidents to ensure continuity of the required safety function. The design

should incorporate sufficient instrument independence, redundancy and/or diversity to ensure that a

single failure will not result in a loss of monitoring capability for safety-class systems. The different

designs and operating characteristics of fusion facilities limit the amount of specific guidance that can

be provided. However, helpful general guidance for implementing this criteria at a particular fusion

facility may be obtained by reviewing the existing DOE and NRC design requirements and guidance

documents (IEEE 603, DOE 6430.1A (a), NUREG-0800, 10CFR50(A), RG 1.47). The power to

operate safety-class instrumentation should meet the requirements of Class 1E Electric Power

Systems (IEEE 308).

Vacuum Vessel Penetrations

For vacuum vessel containment penetrations, each line that is part of the vacuum vessel pressure

boundary and that penetrates the vacuum vessel should be provided with isolation valves, unless it

can be demonstrated that the containment isolation provisions for a specific class of lines, such as

instrument lines, are acceptable on some other defined basis. A simple check valve should not be

used as the automatic isolation valve outside containment. Isolation valves outside containment

should be located as close to containment as practical and upon loss of actuating power, automatic

isolation valves should be designed to take the position that provides greater safety. The power to

operate isolation valves should meet the requirements of Class 1E Electric Power Systems (IEEE

308).

Ventilation and Exhaust System Criteria

Confinement Systems

The design of a vacuum vessel confinement ventilation system should ensure the ability to maintain

desired airflow characteristics when personnel access ports or hatches are open. When necessary,

air locks or enclosed vestibules should be used to minimize the impact of this air flow on the

ventilation system and to prevent the spread of airborne contamination within the facility. The

ventilation system design should provide the required confinement capability under all normal

operations and design basis accidents with the assumption of a single failure in the system. If the

maintenance of a controlled continuous confinement airflow is required, electrical equipment and

components required to provide this airflow should be supplied with safety-class electrical power and

provided with a backup power source. Air cleanup systems should be provided in confinement

ventilation exhaust systems to limit the release of radioactive or other hazardous material to the

environment and to minimize the spread of contamination within the facility as determined by the

safety analysis. Guidance for confinement systems is included in DOE 6430.1A (b).