Recommendations for Improvements for Product Containers

DOE-HDBK-1129-99

end of the port tube inside the vessel. The purpose of the filters is to confine the uranium powder.

One filter is positioned in the volume above the uranium and is connected through a valve to the

female port with a Cajon SS-4-VCR-1 female nut. The second filter, connected through the valve

to the male port, is positioned below the level of the uranium powder in the bottom of the vessel

and is connected through the valve to the male port with a Cajon SS-4-VCR-4 male nut. Both

ports are used when the bed is used in a flow-through mode of operation.

The maximum normal unloading temperature is 450oC, and the maximum unloading pressure at

temperature is 2.9 psia. Exceeding the 2.9 psia pressure at temperature will impact the vessel

service life.

When uranium is loaded to full stoichiometry with tritium to form UT3, it retains the decay helium in

the solid for about 300 days until the concentration of helium reaches approximately 0.134 He/U,

after which, some of the helium will be released from the solid. The helium release rate increases

over a period of about 600 days, until it equalizes with the helium generation rate.

The HTV Dissociation Pressure [33], P is

log Patm = -(4038.2/T) + 6.074

where T = temperature (K)

which implies

Patm = 10 -(4038.2/T) + 6.074

The second equation for the HTV Dissociation Pressure is

log P psia = -(4038.2/T) + 7.2413

which implies

Ppsia = 10 -(4038.2/T) + 7.2413

WSRC conducted several tests on the HTV to determine the impact of an air ingress incident. The

results indicate that in the dehydride state, the uranium reacted with both oxygen and nitrogen in

the air. The reaction stopped when the accumulation of argon and moisture in the vessel reached

atmospheric pressure and prevented additional air from entering the vessel. The maximum

temperature was approximately 200oC. If air is drawn through the uranium continuously, a

temperature higher than 1,000oC can be reached, and damage to the vessel may occur. There are

some current issues associated with HTV qualification and use that are being addressed at SRS,

the results of which will be included in the next revision to this document.

6.2.3 Recommendations for Improvements for Product Containers

Both the PV and HTV containers are single-valve designs (although the HTV actually has two

valves; one for filling and one for evacuating), employing an SS-4HS-TW valve. Selection of this

valve was based in part on the favorable rating it received against valves of similar size. It is rated

at 315C and 1000 psig. Additionally, the valve stem tip is StelliteTM spherical design, a desirable

tip configuration. Although the leak rate is verified annually at SRS, the employment of a single H-

type valve close to the heat zone is not an optimal design, as described in EH Technical Notice 94-