In large microwavable bowl, mix cereal and walnuts; set aside.
In 2-cup microwavable measuring cup, microwave brown sugar, orange juice concentrate and oil on High 1 minute; stir. Microwave about 1 minute longer, stirring after 30 seconds, until mixture is hot. Pour over cereal mixture, stirring until evenly coated.
Microwave uncovered on High 5 minutes, stirring every 2 minutes. Stir in cranberries. Spread on waxed paper or foil to cool. Store in tightly covered container.