Nuclear-energy officials arrived in Brussels this week amid a growing wave of public support for atomic power. They left humbled by the tepid reaction of bankers assessing the price tag of their ambitions.The International Atomic Energy Agency convened a summit to build momentum for a low-emissions technology that many expect will be critical for hitting climate targets. A group of mostly Western countries pledged to triple nuclear generation by 2050. But lenders balked at the eyewatering cost o...