Electrical - hdbk60040121

DOE-HDBK-6004-99

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

exposure. 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 anticipated hazards. The specific hazards to be addressed are relative to the

equipment's expected location within the fusion facility.

The contamination issue should be addressed by careful surface selection and preparation to prevent

the entrapment of radiological materials and facilitate the removal of material. Metal surface

characteristics should be smooth and free of paints or coatings, with the except 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.

Electrical

The remote systems should be designed to the equivalent of the National Fire Protection Association

Class 1, Division 1 requirements. It is assumed, but not required, that this would be met with the

pressurized, interlocked systems approach.

Wiring should be resistant to radiological damage. 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 type, 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.

The wiring count from remote equipment to personnel areas should be minimized. The failure

potential for remote handling equipment is directly related to the amount of vulnerable wiring, and

connectors required from the work area.

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