Evaluation of nylon 6,6 in use in Fire Foe® fire suppression systems within plutonium gloveboxes

Gloveboxes, where special nuclear material is handled and such as those present at Los Alamos National Labs, LANL, provide an experimental area confined within a protective shell and with strict environmental controls. These gloveboxes allow workers to indirectly interact with hazardous material. Unfortunately, these gloveboxes are not fail proof and are subject to occasional accidental failures resulting in possible breaches of containment and release of nuclear material. In particular, fires within the gloveboxes are of major concern with regard to the potential for breaches and damage to not only the glovebox but also to surrounding areas as well. Another, potentially even catastrophic, result of glovebox fires is the potential for the spread of radioactive contamination. There is some historical precedent of contaminant release resulting from glovebox fires, such as those at the Rocky Flats Plant (Buffer, 2012).

Gloveboxes at LANL are currently equipped with manually activated fire suppression systems. In the event of an incident, a worker would hit a nearby emergency button and the system would be activated. However, this method relies on the worker to have the presence of mind in the face of danger to activate the system, and as such there is no true guarantee that the systems will be triggered. Since the level of consequence is dire, then the ideal situation requires that other fire suppression systems be present which do not rely on human interaction to function. The Fire Foe™ system has been chosen as a secondary failsafe measure in order to meet this need.

Analysis of how the casing of the Fire Foe™ system, composed of nylon 6,6 polymer, weathers under irradiation in gloveboxes is paramount in determining the effectiveness and potential lifetimes of the systems within the gloveboxes. Samples of nylon 6,6 were exposed to a 5 Ci PuBe neutron source located at the University of Texas as well as a high dose rate beam of 4.5 MeV alpha particles located at Los Alamos to determine the effect of neutron and alpha particle damage on the polymer material. Subsequent mechanical testing was conducted to determine alteration to the tensile properties of the nylon 6,6 material for both irradiated and non-irradiated samples.