Its hard but not impossible to pass. Were you at a DOE site? Its a little different material than the CORE exam (more geared to commercial) but I wouldn't say any harder than the Core. Many sites would like you to have passed it prior to showing up or at least be ready to pass it the day you show up. Your contract company should send you study material. There are forums with NEU questions to help quiz you. Just know detector theory, algebra, basic radiation physics and good radiological safety practices and you should be okay.