Surely the 787 engineers and their bosses in Chicago realize that all eight Special Conditions for the use of Lithium Ion batteries (posted at #111) are US Federal Law. It is not a legal option to just contain any battery fire, Boeing must also prove:
(1) Safe cell temperatures and pressures must be maintained during any foreseeable …. condition ….
(2) Design of the lithium ion batteries must preclude the occurrence of self-sustaining, uncontrolled increases in temperature or pressure.
Nor would containment alone be publicly acceptable. Boeing had best follow Airbus and revert to NiCads.
FWIW my views with historic context are published at:
Dreamliner's assault and battery on Boeing's name