Preheat oven to 350 degrees. Grease a 9X5 inch loaf pan.
In a large bowl, whisk together the flour, sugar, baking powder, baking soda and salt. In a medium sized bowl, combine the orange juice, zest, buttermilk, egg and vegetable oil.
Add the wet ingredients to the dry ingredients and mix until combined. Stir in the cranberries and nuts, then pour batter into loaf pan. Bake for 55 to 65 minutes, or until tester inserted in the center of the loaf comes out clean and the bread starts to pull away from the edges of teh pan. Remove it from the oven and let cool for 15 minute, then turn it out of the pan to cool completely on a rack.
The loaf will slice better if wrapped when cooled and left to rest overnight before serving.