CREATE TABLE table_14736 ("Unit" TEXT, "Reactor type" TEXT, "Net capacity" TEXT, "Gross capacity" TEXT, "Construction started" TEXT, "Electricity grid" TEXT, "Commercial operation" TEXT, "Shutdown" TEXT)

What reactor type that has a commercial operation of , and a tianwan-7 unit?
SELECT "Reactor type" FROM table_14736 WHERE "Commercial operation" = '—' AND "Unit" = 'tianwan-7'
SELECT "Reactor type" FROM "table_14736" WHERE "Commercial operation" = '—' AND "Unit" = 'tianwan-7'