Table 2-3. Dissociation pressure equation parameters for uranium hydride, deuteride, and tritide

DOE-HDBK-1129-99

He, N2, O2, or Ar, either remain in the overpressure gas in the bed or react with uranium to form

stable compounds. Inert gases, such as Ar, will remain in the overpressure gas, and can be

removed by pumping off with a vacuum pump after the pressure has stabilized; however, helium-3

cannot be pumped off without first heating the bed. N2 and O2 will react chemically with the

uranium to form stable uranium compounds in the bed, and, therefore, cannot be pumped off at all.

As the temperature of the bed is increased, the tritium partial pressure increases as a function of

temperature. Depending upon the U:T ratio, it can reach a pressure of around 500 pounds per

square inch absolute (psia) at 600oC. The tritium may be transferred into and out of manifolds,

containers, etc., by heating the bed and then cooling it to room temperature. The general form of

the equation for the dissociation pressure, P, in millimeters of mercury (mm) for uranium hydride,

deuteride, and tritide is:

log Pmm = - A/T + B

Pmm = 10 (A/T(K)) + B

where T = temperature (K)

The values for A and B for hydrogen, deuterium, and tritium, determined by several different

investigators, are listed in the following paragraphs, and the results are shown in Table 2-3 and

plotted in Figure 2-4. Figure 2-5 is a plot of the general characteristics of uranium hydride,

deuteride, and tritide.

TABLE 2-3. Dissociation pressure equation parameters for uranium hydride, deuteride, and tritide

Temperature

(C) required to

Temperature

generate a

Range (oC)

Metal

pressure of

Tritide

Reference

Investigated

(/Kelvin)

1 atmosphere

UH3

Spedding, et al.

260 to 430

4500

9.28

430

Destriau & Seriot

243 to 412

4255

9.08

415

Wicke & Otto

200 to 430

4450

9.20

434

Mogard & Cabane

500 to 650

4480

9.20

435

Libowitz & Gibb

450 to 650

4410

9.14

432

UD3

Spedding, et al.

unspecified

4500

9.43

414

Destriau & Seriot

unspecified

4401

9.01

445

Wicke & Otto

unspecified

4500

9.40

417

UT3

Flotow & Abraham

unspecified

4471

9.461

408

WSRC

unspecified

4038.2

6.074

unspecified