cp-1-reactor (IMAGE) DOE/Argonne National Laboratory Caption Scientists built Chicago Pile 1, the world’s first nuclear reactor, layer by layer beneath the University of Chicago’s Stagg Field. In this photo, the layer shows graphite bricks with small holes for uranium or control rods used during the experiment. Credit (Image by Argonne National Laboratory.) Usage Restrictions Original content License Original content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.