When did the Electricity Grid 28.12.1972 officially shutdown?
CREATE TABLE "reactor_data" (
  "unit" text,
  "reactortype" text,
  "net_capacity" text,
  "gross_capacity" text,
  "construction_started" text,
  "electricity_grid" text,
  "commercial_operation" text,
  "shutdown" text
);
SELECT "shutdown" FROM "reactor_data" WHERE "electricity_grid"='28.12.1972';