Design studies for high-level nuclear waste packages for salt repositories have identified low-carbon steel as a candidate material for containers. Among the requirements are strength, corrosion resistance, and fabricability. The studies of the corrosion resistance and structural stability of iron-base materials (particularly lowcarbon steel) are treated in this paper. The materials have been exposed in brines that are characteristic of the potential sites for salt repositories. The effects of temperature, radiation level, oxygen level and other parameters are under investigation. The initial development of corrosion models for these environments is presented with discussion of the key mechanisms under consideration.

An oil-free vacuum system capable of achieving vacuum levels of 10−6 Torr for in-pile experiments has been constructed at the pool-type Battelle Research Reactor (BRR). The pumping system which is mounted on a moveable bridge above the pool surface, consists of a 7500 liter/sec titanium sublimation pump and two 350-liter/sec triode-type ion pumps; system roughing is accomplished with a roots-type blower with a double-walled liquid nitrogen trap. Nine meters of 20.3-cm (8-in.) diam vacuum piping connect the pumping system to a test chamber at the core level. Test chamber geometry can be varied to fit either a 7.62×7.62-cm test cell or the core face. Neutron fluxes of 2×1013 neutron/cm2⋅sec (thermal) and 1×1013 neutron/cm2⋅sec (fast) are available and the maximum gamma rate is 108 R/h. Adjustments of desired gamma/neutron ratio are made by employing appropriate shielding at the core face. Irradiation effects on the performance of electro-mechanical components for space nuclear power systems have been studied at elevated temperatures (620–820 K) and a full-scale nuclear fueled thermionic diode is currently being prepared for irradiation in the system.

Proper planning for maintenance and inspection tends to increase the overall availability of nuclear power plants. High potential availability is the basic measure of a successful power plant since replacement power costs are high. The study reported here compared the maintenance and inspection requirements of generic pool and loop type LMFBRs to determine if there were significant differences in these two systems owing to their fundamental difference in design. The size, number and types of failed components affected downtime for maintenance but accessibility and arrangement of components also strongly influenced the downtime.

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