phase make it probable that a new test protocol will be needed to address the unique characteristics of these metal matrices and the effects of these properties on the long-term acceptability of the waste form. As with zeolite waste forms, the acceptability of the metal waste form should depend on the performance of an integrated system of isolation barriers that includes the waste form as the initial location and source of radionuclides.

In the area of radioelement loading of zeolite columns, particular emphasis should be given to

• establishing the range of parameters, with respect to zeolite type, configuration, and operating conditions, that give satisfactory column performance, and

• determining the thermal, chemical, mechanical, and radiological stability of zeolite under expected column loading conditions.

For testing and evaluation of waste forms, the committee recommends the following:

• A schedule should be developed and implemented for demonstrating waste form performance over a time period commensurate with DOE' s plans for treatment of spent nuclear fuel and conversion of WPu to a form suitable for ultimate disposal. Evaluation of waste form performance is of equal concern for application of the electrometallurgical technique to treatment of DOE SNF, although the latter application is governed by a different schedule.

• Waste-form testing should be conducted on the “as-produced” zeolite host phase for radionuclides, as well as on the GBZ waste form.