Sensible, Timely Relief for America's Nuclear Districts' Economic Development Act of 2021 or the STRANDED Act of 2021 This bill provides resources to communities affected by stranded nuclear waste. The bill defines stranded nuclear waste as nuclear waste or spent nuclear fuel stored in dry casks or spent fuel pools at the site of an eligible civilian nuclear power plant. Specifically, the bill provides a first-time homebuyer tax credit for homeownership in nuclear affected communities. In addition, the bill directs the Economic Development Administration to establish a competitive prize competition to award prizes to affected communities for proposals to carry out alternatives to nuclear facilities, generating sites, and waste sites. The bill also provides grants to nuclear-affected communities to (1) offset the economic and social impacts of stranded nuclear waste on such communities, and (2) support such communities that are facing decreased tax revenues or assessed valuation as a result of decommissioning a civilian nuclear power plant.