B787 First Officer reported the right landing gear brake had seized during taxi; resulting in abnormally high brake temperatures. Flight crew stopped taxi and aircraft was towed back to the gate.

Narrative

Aircraft was dispatched with a single brake antiskid MEL on the right gear. Appropriate penalties were applied; and MEL procedures briefed. On taxi out; after about 3/4 of a mile or so; the brake temp EICAS displayed. As monitoring pilot; I opened up the system page and checklist after the Captain stopped the airplane on Taxiway 1 short of 2. We immediately noticed the brake temp rising rapidly towards the highest observed temp of 8.3. Upon stopping; the temps dropped fairly quickly. We ran the checklist and then contacted Maintenance Control and Operations. It was clear to us that further taxi under power was possibly dangerous; so we coordinated with Operations for a tow and gate. The fire truck also came out and verified the brake was cooling; and Maintenance inspected the brake so we could be towed. On tow back we observed the same brake increase in temp again; so we communicated this and slowed the taxi. Temps stabilized at 4.3 to the gate. We additionally noted air pressure increases on the corresponding tire to upwards of 271. All of this was communicated with Maintenance. Upon further inspection at the gate; it was determined the brake had seized.