TJNAF seeks engineering services to validate the Neutron Source (SNS) Sub-atmospheric Cold Box vacuum vessel design against the specifications provided in the RFP package. Offerors must submit a proposal demonstrating capability and understanding of TJNAF’s requirements. The selection process will be full and open competition using a Best Value/Trade-Off approach. Award is intended no later than 30 September 2026. The resulting subcontract will be firm fixed price.