Stabilize any other potential gas-producing constituents

DOE-STD-3013-2004

by calcination at 950C [Waterbury et al. 1961]. All other nitrates and carbonates

are expected to be decomposed by this procedure. Sulfate is known to be

incorporated into plutonium oxide prepared by peroxide precipitation from

sulfuric acid solutions [Leary et al. 1957]. The report of Moseley and Wing

[Moseley/Wing 1965] shows that 950C calcination is sufficient to destroy this

sulfate constituent. Literature searches indicate that deleterious amounts of

radiolytic gases from residual sulfate and chloride contaminants are unlikely in

the long-term storage conditions anticipated for stabilized materials [Tandon et

al. 1999a, Tandon et al. 1999b and references therein].

The preceding discussion addresses stabilization issues for plutonium oxide materials

that are rooted in safety concerns. An additional issue for these materials, which is

based more in operational than safety concerns, is the behavior of salt impurities in

plutonium oxides that have resulted from pyrochemical operations. The common

impurities NaCl and KCl, which can achieve levels of tens of percent in unstabilized

impure oxides being addressed by this Standard, have moderate volatilities above

800C. The practical impact of moderate volatilities is that materials with these

characteristics have difficulty meeting the 0.5 wt% LOI criterion with reasonable

calcination times. (Corrosion implications of chlorides during storage are addressed

in Section A.6.3 of this Appendix.) A second concern is the maintenance impact of

volatilized salts on furnace and off-gas systems. Salt volatilization is much more

problematic at 950C than at 800C because the vapor pressures of NaCl and KCl are

roughly an order of magnitude greater at the higher temperature. This Standard

retains the 950C calcination criterion of Standard 3013-99 but recommends that

operational complications regarding salt evolution be carefully monitored. Section 5

of the Forward, third bullet states that "Determination that a proposed alternative

criterion or alternative approach to satisfying one or more criteria is technically

equivalent, in terms of safety, to the Standard Criteria" may be submitted, technically

justified, and approved by the DOE. The DOE has approved two submittals as

technically equivalent in the past two years (re Boak et. al. (a and b)). This process

has proved efficient, cost effective, and timely for both Rocky Flats and Richland.

The technical equivalency evaluations were based on well-characterized material,

with no impurities that could cause pressurization, and subsequently stabilized

materials were tested to the same requirements (loss on ignition, etc.) previously