In a small bowl combine well the apricots, the walnuts, the brown sugar, and the butter. Core the apples, making each opening large enough to hold half the apricot mixture, peel the top third of each apple, and fill the cavities with the apricot mixture. Arrange the apples in a deep 2 1/2-quart microwave-safe baking dish so that they do not touch one another or the sides of the dish, pour the orange juice around them, and microwave the apples on high power (lOO%), covered with micro wave-safe plastic wrap, for 7 minutes. Pierce the plastic wrap with the tip of a sharp knife and let the apples stand covered, for 5 minutes, or until they are tender.