Maintenance - hdbk60040051

DOE-HDBK-6004-99

2. Provide for monitors and signals or alarms dictating a need to isolate or otherwise control a

tritium system to prevent monitored system variables exceeding a safety limit. The safety analysis

should identify the system variables requiring monitoring, which will normally include system

pressure, oxygen inleakage and tritium out leakage from a confinement barrier.

3. Provide for recovery from anticipated off-normal events by providing systems that remove tritium

from secondary and greater confinements and from any air stream exhausting a confinement to

the environment.

Maintenance:

1. Provide for primary confinement of tritium during maintenance within secondary, tertiary or any

greater levels of confinement barriers.

2. Provide for tritium removal, evacuation and cleansing of primary confinement systems prior to

breaking the primary confinement barrier for maintenance. This preparation for maintenance will

minimize the resultant tritium losses.

Design Basis Accidents:

The safety analysis should specify design basis accidents. Tritium systems design should implement

requirements and provide for corresponding safety functions to make the accident consequences

acceptable.

A typical frequency for design basis accidents is P>10-6/year. The safety analysis will specify the

actual frequency. The quantity and form of tritium released during a design basis accident will

determine the consequences of the accident. Probability and consequence are the parameters

determining risk. The following are potential design basis accidents for tritium systems:

Internal Initiators

1. Tritium fire or detonation

2. Missile or pipe whip resulting from sudden failure of high energy system. This accident has

potential for causing a release of tritium and simultaneously disrupting multiple confinement

barriers.

3. Human errors

External Initiators

1. Natural phenomena, including earthquakes, hurricanes, tornadoes, floods, tsunami, etc.

2. Aircraft and other missile impact (excluding sabotage).

Beyond Design Basis Accidents:

There are no system safety functions required for beyond design basis accidents.