explosion in a glove box

This event occurred at a laboratory researching storage of hydrogen in complex hydrides. Sodium aluminium hydride (also called sodium alanate, NaAlH4) powder mixed with hexane (C6H14) was placed in two metal trays and dried by placement in a glove box antechamber under vacuum.
After several days, the trays were moved into the glove box main chamber. The sodium alanate powder had to be transferred into another container. This operation (not further detailed by the report) implied the use of a spatula to scrap the powder from metallic surface. This operation created the condition for the explosive reaction of a portion of the powder in the tray. The pressure pulse cracked the window at the back of the glove box.

No injuries occurred, and the glove box window was resealed using tape within one to two minutes.

The INITATING CAUSE was very probably the reaction of the sodium alanate powder with moisture accidentally entered the glove box.
It was not possible to obtain direct evidence of the substances causing the reaction, but it is known that sodium alanate is highly reactive to water or water vapour. A possible explanation of the presence of moisture in the glove box, is a small leak in the antechamber seals. Another is the back diffusion from the vacuum pump.
In absence of details related to the safety management of the glove box, the ROOT CAUSE remains unknown.

sodium alanate,
complex metal hydride,
glove box

DESCRIPTION OF THE SUBSTANCES INVOLVED
Sodium aluminium hydride is an inorganic compound with the chemical formula NaAlH4.
Its importance in this context derives from its potential as storage of hydrogen, with the
Reactions, catalysed by a titanium (compound):
3 NaAlH4 → Na3AlH6+ 2 Al + 3 H2
Na3AlH6 → 3 NaH + Al + 3/2 H2

The reaction with water:
4 H2O + NaAlH4 → "NaAl(OH)4" + 4 H2
[from Wikipedia: https://en.wikipedia.org/wiki/Sodium_aluminium_hydride ]

Hexane is an organic compound used, among other application, as non-polar solvent. In this laboratory, it was probably used as safe storage and particle dispersing agent along the production and handling route of the NaAlH4. Its melting point is around −95°C and its boiling point around 69 °C, and it is easily evaporated.
[from Wikipedia: https://en.wikipedia.org/wiki/Hexane ]

property damage were liitd to the glass of the glove box.

In addition to resealing the glove box window, a positive pressure of argon gas was maintained inside the glove box until repair. The glove box was then cleaned up by specialised personnel using natural bristle brushes and plastic utensils.

In general, the pre-chamber of a glovebox is not designed for materials treatment as the one executed in this event. If unavoidable, the vacuum-pressurisation cycles necessary before moving he materials into the main chamber should be repeated more often than prescribed by the manufacturer guidelines. Moreover, NaAlH4 or other reactive hydrogen storage materials requires extra precautions with regards to sealing and vacuum pump performance, especially when holding these materials under vacuum for extended periods of time.

The H2TOOLS report does not mention the safety features available in the affected glovebox. Moisture level inside glove boxed when moisture-sensitive materials are handled there, presence of moisture should monitor, and possible controlled.

To handle the sodium alanate powder inside the glove box, the metallic tools were replaced by Teflon-coated magnetic stirring bars.