Material Requirements

DOE-HDBK-6004-99

The activation and degradation issues should be addressed by the careful choice of materials, to

minimize these effects. The contamination issue should be addressed by careful surface preparation

to both prevent the entrapment of radiological materials and facilitate the removal of material.

Replaceable materials should be radiation tolerant to 1 x 109 rads of cumulative dosage. Materials

that are inaccessible or otherwise difficult to replace should be radiation tolerant to 1 x 109 rads

cumulative exposure.

Material Requirements

All structural materials used should be chosen for their non oxidizing surface characteristics and

resistance to neutron activation, to the extent possible. Stainless steels should be used unless other

materials are agreed upon.

Non metallic materials should be chosen for their resistance to neutron activation and to radiological

degradation. The failure mode of the materials should not directly cause failures of other systems

(e.g. elastomers that become liquids upon radiological exposure). Non metallic materials should not

be used that cause degradation of adjoining metallic materials, such as materials that release chlorine.

All metallic and non metallic materials used should be resistant to the chemical, high temperature, low

temperature, and other hazards unique to fusion facilities. The specific hazards to be addressed are

relative to the equipment's expected location within the fusion facility.

Metal surface characteristics should be smooth and free of paints or coatings, with the exception of

strippable coatings used for decontamination. High polish or electropolished surfaces are preferred,

due to their ease of decontamination.

All metallic and non metallic materials should be resistant to decontamination processes to be used

prior to maintenance. These methods include cleaning with high pressure water, cryogenic materials,

and mild acids. Special care must be used to prevent gaps and crevices from entrapping and retaining

radiological materials.

Wiring Requirements

Wiring should be resistant to radiological damage to the levels stated in this report. All cabling

should be protected from physical hazards expected within the very large fusion facility.

Cabling should be adequately shielded from the high magnetic and radio frequency fields it is expected

to encounter. The shielding should be such that the equipment serviced by that cabling is adequately

protected from cabling induced interference.

Electrical connectors and wiring methods (per National Electrical Code definitions, or equivalent)

should be used to minimize repair or replacement time. Sealed, quick-disconnect connectors should

be used wherever possible and all individual wiring methods (e.g. terminal strips) should be avoided.

These requirements are intended to minimize the exposure of personnel related to maintenance.