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Advanced Radiation Shielding

Description:

OUSD (R&E) MODERNIZATION PRIORITY: Directed Energy, Nuclear, Space TECHNOLOGY AREA(S): Materials/Processes, Nuclear Technology, Space Platform OBJECTIVE: Develop a new material system capable of more effective high energy gamma-ray shielding than traditional materials such a lead and concrete at comparable cost. DESCRIPTION: There are various operational environments where shielding is required to protect people and sensitive electronics from ionizing radiation. These include space environments, areas with highly radioactive materials or areas near intense nuclear reactions, such as fission and fusion sources. Although traditional radiation shielding materials have largely been suitable, developing a new material system that provides 10x more effective shielding compared to traditional materials, or that were 10x lighter or more compact than traditional materials while providing equivalent shielding would enable a range of missions where traditional shielding is inadequate. This topic seeks innovation in novel materials for shielding gamma ray radiation at MeV to GeV energies, capable of withstanding high fluences, that can be produced inexpensively and in large quantities, and ideally with flexible form factors. Specifically, at 1 MeV to 100 MeV energy levels, a material that provides twice or greater the linear attenuation coefficient at comparable density to existing shielding materials is being sought. The table below summarizes the mass and linear attenuation coefficients of three common shielding materials, concrete, iron, and lead, and the goal for two-times (or greater) linear attenuation coefficients at these energies: Density (g/cm3) mu/rho (cm2/g) mu/rho (cm2/g) mu (cm-1) mu (cm-1) 1 MeV 100 MeV 1 MeV 100 MeV Pb 11.35 0.0710 0.0931 0.806 1.057 Fe 7.87 0.0600 0.0433 0.472 0.341 Concrete 2.3 0.0650 0.0221 0.149 0.051 Pb Goals >x2: 1.612 2.113 Fe 0.944 0.682 Concrete 0.299 0.102 PHASE I: Phase I is a feasibility study that would demonstrate the scientific, technical, and commercial merit and feasibility of the concept resulting in a basic material system and credible material production flow. Activities could include material modeling, basic material synthesis, fabrication experiments, and material system characterization. Key materials characteristics and interfaces should be identified and quantified showing how attenuation goals could be achieved in terms of necessary shielding and high-volume production cost. Challenges and risks in perfecting shielding characteristics, and scaling the shielding material to required volumes for practical applications must be identified and proposed mitigation strategies presented. Schedule/Milestones/Deliverables. Phase I fixed payable milestones for this program should include: • Month 1: Initial report on proposed material system, with modeling and empirical data and discussion of Phase 1 goals. • Month 3: Report on modifying and scaling of proposed material system and required adjustments to achieve program goals supported by experimental, simulated or modeled data • Month 5: Interim report describing performance and cost of proposed material system • Month 7: Update to interim report. Given this report needs to support the Phase 2 proposal, it should provide compelling evidence the material system and its synthesis/fabrication can achieve overall program goals. • Month 8: Final Phase I report summarizing technical approach and status in achieving Phase I goals, and plans to achieve program goals by the end of Ph 2. This should be a culmination of the Phase 1 effort, demonstrating a viable technical path supported by empirical and modeling data to achieving overall program goals, with risks and mitigation strategies fully detailed. Monthly written technical progress reports (see template under SBIR/STTR BAA DOCUMENTS at https://www.darpa.mil/work-with-us/for-small-businesses/participate-sbir-sttr-program). All proposals must include the following meetings in the proposed schedule and costs: • Virtual kickoff for Phase 1; and • Regular monthly teleconference meetings with the Government team for progress reporting as well as problem identification and mitigation. Proposers typically prepare a slide deck to aid in the discussion. PHASE II: Phase II builds upon feasibility established in Phase I and ultimately produces and demonstrates a TRL 5 prototype material meeting Section II b goals. The Phase II base period (year 1) will focus on overall material system development and characterization and scalable process development. The Phase II increment period (year 2) will refine material production processes, refine shielding performance and conduct initial practical demonstrations. The Phase II option period (year 3) will produce usable quantities of the optimized material system with demonstrated low-cost techniques, and support demonstrations meeting program goals. Schedule/Milestones/Deliverables. Phase II fixed payable milestones for this program should include: • Month 1: Phase 2 Kickoff. Slide deck summarizing technical approach to meet overall goals, risks and risk mitigations, and quantified milestone schedule • Month 9: Preliminary Design Review. Report capturing the refinement of the material system to achieve performance and cost goals • Month 12: Interim material characterization: Report characterizing the performance of the photon absorbing material produced from a scalable process. • Month 15: Critical Design Review. Report capturing the final material system design that when realized credibly achieves the overall performance and suitability goals. • Month 18: Interim Integration Report: Report describing results to date in integrating the absorbing/attenuating material with demonstrations of interest. • Month 24: Final Report: End of base period report that summarizes >10x attenuation performance and results of initial practical demonstrations. • Option Schedule/Milestones/Deliverables • Month 30: Interim Option Period Performance Report. • Month 36: Final Phase II Report. Summary of material system performance, testing, production at low cost, and demonstrations meeting program goals. Delivery of the prototype material system to the Government or its designee. Monthly written technical progress reports (see template under SBIR/STTR BAA DOCUMENTS at https://www.darpa.mil/work-with-us/for-small-businesses/participate-sbir-sttr-program). All proposals must include the following meetings in the proposed schedule and costs: • Virtual kickoff for Phase II; • Regular monthly teleconference meetings with the Government team for progress reporting as well as problem identification and mitigation. Proposers typically prepare a slide deck to aid in the discussion; and • Depending on travel conditions, proposers should anticipate at least one site visit during Phase 2 by the DARPA Program Manager during which they will have the opportunity to demonstrate progress towards agreed-upon milestones. PHASE III DUAL USE APPLICATIONS: Successful development of the subject material system will be applied in demonstration of relevant DoD and commercial applications, with commercialization strategies developed for each. Military electronics in space environments would be one such example. For commercial applications, targeting applications where traditional shielding poses challenges to effective implementation will be targeted. These may include irradiation facilities, reactor applications, and high energy physics applications. REFERENCES: 1. NIST X-Ray Mass Attenuation Coefficients: https://physics.nist.gov/PhysRefData/Xcom/html/xcom1.html; https://physics.nist.gov/PhysRefData/XrayMassCoef/tab2.html KEYWORDS: Radiation, Shielding, Gamma-rays, X-rays, Nanomaterials, Quantum dots, High Z materials
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