CREATE TABLE table_19257 ("AGR Power Station" TEXT, "Net MWe" FLOAT, "Construction started" FLOAT, "Connected to grid" FLOAT, "Commercial operation" FLOAT, "Accounting closure date" FLOAT)

What is the Closure date of Hunterston B
SELECT MIN("Accounting closure date") FROM table_19257 WHERE "AGR Power Station" = 'Hunterston B'
SELECT MIN("Accounting closure date") FROM "table_19257" WHERE "AGR Power Station" = 'Hunterston B'