Chemical Hazards

DOE-STD-6003-96

related to the structural material. The use of low activation materials for fusion structural compo-

nents can influence the potential hazard. The majority of these activation products (~98 to 99%)

will be bound in solid metal structures such as the first wall, blanket, and divertor and would only

be mobilized during off-normal conditions. Mechanisms for mobilization include partial vaporiza-

tion during a plasma disruption, oxidation-driven volatilization due to chemical reactions of the

structure with air and/or steam, and magnet coil electrical arcing.

Smaller inventories of activation products include the following:

a. corrosion products that will be circulating in coolant streams from actively cooled

structures like the blanket and divertor,

b. "tokamak dust" produced by erosion of material from the surfaces facing the plasma

due to interaction with high-energy neutrals and ions from the plasma, and

c. activated air inside the building as a result of neutron leakage and streaming.

These activation product inventories are operational, maintenance, and accident

concerns.

The hazard associated with activation products is a function of the structural, PFC, and

coolant materials that are used in the design, the power level of the machine, and the expected

neutron fluence.

B.2.2 Chemical Hazards

Many fusion devices may use materials that are chemical hazards. For example, beryl-

lium is the current plasma facing material of choice for ITER. It is toxic, and special precautions

need to be taken to work with it, as demonstrated at the Joint European Torus (JET), a large

tokamak in the United Kingdom. Vanadium, a potential low-activation structural material, is

chemically hazardous when in the oxide form. Because of the production of metallic dust in the

tokamak, the hazard of PFC materials that are not normally considered toxic in solid form needs

to be examined.

B.2.3 Industrial Hazards

Industrial hazards associated with fusion include asphyxiant gases, radio frequency (RF)

fields, high voltage, magnetic fields, and heavy lifts. Many of the fusion machines will use super-

conducting magnets and/or cryopumps that are cooled with liquid nitrogen and helium. Acci-

dental release of these gases would displace oxygen and could be an occupational hazard (e.g.,

suffocation). Some fusion machines will use RF heating as a means to supply power to the

plasma to obtain ignition. Some may use neutral beam injectors. Both have high-voltage

hazards. The magnets used to confine the plasma can cause high external magnetic fields. The

RF fields and magnetic fields are hazards that needs to be managed at the facility during opera-

tion. None of these hazards are unique to fusion per se but are included for completeness.

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