COMBINE BROTH, WATER, CARROTS, CELERY, CHICKEN AND RICE (ALONG WITH SEASONING PACKET) IN A LARGE SLOW COOKER. COOK ON LOW FOR 6 HOURS OR ON HIGH FOR 4 HOURS. TAKE OUT CHICKEN AND SHRED WITH TWO FORKS AND THEN ADD BACK INTO SLOW COOKER. IN A SMALL BOWL COMBINE SALT, PEPPER, AND FLOUR. IN MEDIUM SAUCEPAN OVER MEDIUM HEAT, MELT BUTTER. STIR IN FLOUR MIXTURE BY TABLESPOON TO FORM A ROUX. WHISK IN CREAM, A LITTLE AT A TIME, UNTIL FULLY INCORPORATED AND SMOOTH. STIR CREAM MIXTURE INTO SLOW COOKER AND THEN LET COOK ON LOW FOR 15 MORE MINUTES.