CANFLEX 210G magnox jetronic BBJ2 dimethylhydrazine burnup preburner LiF oxidizer oxy LZ9 qar FSII PBAN unleaded UDMH HCNG Esbit jettisonable octane Mekuria LEU CCAI C2H6O BeO 44LP 103Ru Acclaims TVEL Kugelfischer PEMFC reprocessed pumpout bowsers mainplane SPICA