Launch and Reentry of Space Nuclear Systems AC 450.45-1 Candidate SNS Device and Safety Analysis Results Nuclear Fission System or Has Potential for \ Yes Criticality Using Other Than LEU Fuel ·No Tier III PER ≥ 1x10-° of > 25 Yes rem TED · No Nuclear Fission System or Potential for Has Yes Criticality Using LEU Fuel · No PER ≥ 1x10- of Yes Tier Il 5 to 25 rem TED ·No Total Legend Activity Applicant Produced Product >100,000 Yes Data Driven Conclusion A2 Tier 1 ·No Tier II Tier III Tier I Figure 1- NSPM-20 Tier Level Determination Aid 25
Launch and Reentry of Space Nuclear Systems AC 450.45-1 26
7.2 SNS Safety Guidelines.
7.2.1 As noted earlier, in accordance with § 450.45(e)(6), the FAA will evaluate the launch or reentry of any SNS on a case-by-case basis and issue an approval if the FAA finds that the launch or reentry is consistent with public health and safety, safety of property, and national security and foreign policy interests of the United States. Use of the following criteria (in terms of Probability of Exposure to Radiation (PER)), in conjunction with the analyses set forth in paragraph 8.3 and Appendix A of this AC, is one way to demonstrate that the launch or reentry of the SNS is consistent with public health and safety:5
a. An accident resulting in exposure in excess of 25 millirem but less than 5 rem Total Effective Dose (TED), as defined in 10 CFR § 835.2, to any member of the public is unlikely, such that the probability of such an event does not exceed 1 in 100;
b. An accident resulting in exposure in the range of 5 rem to 25 rem TED to any member of the public is extremely unlikely, such that the probability of such an event does not exceed 1 in 10,000; and
c. The probability of an accident resulting in exposure in excess of 25 rem TED to any member of the public does not exceed 1 in 100,000.
7.2.2 Figure 2 of this AC was created to help applicants visualize potential PERs, the NSPM-20 Tier level based on PER, and the Safety Guidelines, and to identify any unique considerations based on the PER. Because Figure 2 of this AC considers only the PER, it does not capture the full scope of the Tier levels specified above, which can also be impacted by the quantity or type of nuclear material. The Tier levels are the grey, yellow, and gold boxes, while the black line capping the Tier boxes illustrates the SNS Safety Guidelines.
5 These safety guidelines are stated in terms of probability of occurrence for a member of the public receiving ionizing radiation exposure—specifically, the probability of occurrence of a Total Effective Dose of threshold magnitudes. Radiation exposure within these criteria is not expected to cause death or serious injury. However, consistent with the linear no-threshold model of radiation exposure, any amount of radiation is assumed to increase the risk of stochastic radiation effects (e.g. cancer in the exposed individual). To distinguish that SNS radiation exposure is not normally expected to cause casualties, the FAA uses the term Probability of Exposure to Radiation, PER, to describe the probabilistic risks to the public associated with an SNS. The PER is a two-part term, specifying both the probability and magnitude of the dose to the most exposed member of the public.
Launch and Reentry of Space Nuclear Systems AC 450.45-1 PER'S of Note
1.00E+00
1.00E-01 Guidelines of NSPM-20 Exceeds the Safety Exceeds the Probability
1.00E-02 of Casualty to an Tier I Below Lowest Individual (Logsa 1.00E-03 NSPM-20 Specified Dose Member of the Public Threshold Tier I by PER in Title 14 CFR Part
1.00E-05 Tier Il by 450.101 PER Tier I|l by PER
1.00E-06 Contributes to Maximum Probable Loss Determination
1.00E-07
0.001 0.01 Total Effective Dose in Rem (Log Scale) Figure 2 - Considerations Given to Various PER'S
7.2.3 To ensure the individual risk requirements of 14 CFR § 450.101(a)(2) are met, the applicant should select and justify to the FAA a TED value above which a casualty from their operation may occur. In situations where the PER exceeds 1x10-° of a dose greater than this specified TED value, the FAA considers that the Pc exceeds the individual risk limit of § 450.101(a)(2). Figure 2 symbolizes this by the light blue box.
The FAA considers exposure above that TED level a casualty for the purposes of evaluating the risk limit in § 450.101(a)(2). Therefore, such an exposure would violate the regulatory safety criteria defined in § 450.101(a)(2).
7.3 Notes on the Tier Level Definitions.
7.3.1 Subsequent Operation. Embedded in the definition for the various Tier levels is an important detail: the Tier level for an SNS is defined not only by the risk to the public during launch and reentry, but also by the risk to the public during subsequent operation, such as uncontrolled reentry.° Uncontrolled reentry can be initiated in a variety of ways, including malfunction, collision, hacking, deliberate signal " Note that NSPM-20 uses the term "reentry" in a generic sense and is not limited to the reentry of a reentry vehicle as defined in 14 CFR § 401.7.
Launch and Reentry of Space Nuclear Systems AC 450.45-1 28 interference, operator error, etc. Applicants are encouraged to be mindful of how these initiation scenarios might result in inadvertent reentry, and the changes they might have on the SNS prior to, during, or after the uncontrolled reentry to create a robust assessment of potential consequences to a maximally exposed individual member of the public in accident scenarios.
7.3.2 C riticality . Criticality related to an SNS refers to an achievable state of sustained nuclear fission chain reactions (Paxton 1989). Radiological activity is greatly increased for radioactive materials during and after critical or supercritical chain reactions (American Nuclear Society 2018). Criticality depends upon several isotopic and physical or geometrical considerations related to neutron production, moderation, reflection, capture, and leakage. These factors can be changed by changing environmental conditions outside the SNS (Knief 2013). An applicant should consider the specifics of its SNS and all environments their SNS may encounter during normal and abnormal operating conditions to determine if the device is capable of criticality or unintended criticality. This is addressed further in Appendix A of this AC.
7.3.3 Quantities of Radioactive Material.
7.3.3.1 The amount of radioactive material is referenced to the A2 activity level, a level of activity for a specific radionuclide in SI units of TBq, listed in Table 2 of the IAEA SSR-6. This comparison is analogous to the mission multiple (MM), which was used in historical government launches.
Applicants choosing to use MM to describe the activity of their SNS should use the standard definition as shown in the following equation:
𝑴𝑴𝑴𝑴 = � ( 𝑺𝑺𝑺𝑺𝑺𝑺𝑺𝑺𝑺𝑺𝑺𝑺 𝑨𝑨𝑺𝑺𝑨𝑨𝑨𝑨𝑨𝑨 𝑨𝑨𝑨𝑨𝑨𝑨 𝒑𝒑𝑺𝑺 𝑺𝑺 𝑰𝑰 𝑰𝑰𝑺𝑺𝑨𝑨 𝑺𝑺𝒑𝒑𝑺𝑺)𝒏𝒏 (𝑺𝑺𝑺𝑺𝑺𝑺𝑺𝑺𝑺𝑺𝑺𝑺 𝑰𝑰𝑰𝑰𝑺𝑺𝑨𝑨 𝑺𝑺𝒑𝒑𝑨𝑨𝑺𝑺 𝑨𝑨𝑨𝑨 𝑽𝑽𝑽𝑽𝑽𝑽𝑺𝑺 𝑺𝑺)𝒏𝒏𝒏𝒏
Mission Multiple Equation (NASA 2022)
Launch and Reentry of Space Nuclear Systems AC 450.45-1 29
7.3.3.2 MM is a dimensionless integer coefficient that scales a value of the activity level A2. For example, if total activity equals 100,000 × A2, MM equals 100,000. Additional information on specific A2 values, their combination and derivation can be found in:
• IAEA Advisory Material for the IAEA Regulations for the Safe Transport of Radioactive Material, IAEA Safety Standards Series No.
SSG-26, Rev 1, (2018 Edition).
• IAEA, Regulations for the Safe transport of Radioactive Material, IAEA Safety Standards Series No. SSR-6 (Rev.1), 2018.
Launch and Reentry of Space Nuclear Systems AC 450.45-1 8 SPACE NUCLEAR SYSTEM LICENSING PROCESS.
8.1 Overview of Licensing Process
8.1.1 The launch and reentry license process is illustrated in Figure 3 of this AC. Any launch or reentry with an SNS will follow this process. As noted earlier, the FAA will address the unique safety aspects of SNS on a case-by-case basis during the licensing process.
8.1.2 Because of the unique public safety issues raised by use of SNS in commercial launch or reentry activity, the FAA encourages applicants to begin pre-application consultation for launches or reentries involving SNS as early as possible. The pre-application engagement with the FAA provides guidance for the applicant on developing an acceptable application, the roadmap to engaging with other government agencies, and the administrative and technical requirements for the application. This enables a timely and effective licensing evaluation and determination when the application package is complete enough for review.
Pre-Application Consultation* *Pre-Application for New License or Compliance Lifecycle Management of Existing License Planning Templates and Guidance:
**License and Applicant May Request: • Application Letter License Orders Lifecycle • Unique Means or Compliance (MOC) Template Will Reference • even Loved of stay • Application Compliance the Compliance Management Checklist Document Set: • Sample Compliance Document List Compliance document set includes the application data Modify License Issue License or Acceptance for New or Modified License Application • Pre-Application • Means of Compliance Consultation Checklist submittals below: Table
• Crosswalk Mapping to
• Application Letter Legacy Regulations
• Application with FAA Evaluates • Advisory Circulars
• Application Compliance Compliance Documents Determination and Compiles • License & License Orders FAA Makes License • Environmental Review • Policy Review • Safety Review Checklist • Compliance Document Set** • Financial Responsibility • Payload Review
- Any Waivers & ELOS Figure 3 - License Evaluation Process
Launch and Reentry of Space Nuclear Systems AC 450.45-1 31
8.2 Licensing Process for the Launch or Reentry of an SNS.
8.2.1 The FAA issues a vehicle operator license if it determines that the launch or reentry operator can launch or reenter without jeopardizing public health and safety, the safety of property, or the national security or foreign policy interests of the United States. All the data requirements and licensing stages for a conventional launch or reentry, as described in 14 CFR part 450, apply for the launch or reentry of an SNS.
8.2.2 To show compliance with § 450.45(e)(6) specifically, an applicant can provide the information and conduct the analyses described in paragraph 8.3 below and Appendix A of this AC.
8.3 Nuclear Safety Analyses to Demonstrate Acceptable Public Health and Safety.
8.3.1 The scope and content of the nuclear safety analyses demonstrating compliance with the public health and safety criteria should be commensurate with the level of mission radiological risk incurred. Figure 4 provides applicants a way to determine which nuclear safety analyses could be used to demonstrate acceptable level of public health and safety for various SNS, and Appendix A provides details on the scope and intent of the various analyses.
Launch and Reentry of Space Nuclear Systems AC 450.45-1 SNS Device and Mission Description Prepared Radioactive Materials Onboard Report (RMR) Prepared Legend Applicant Produced Product The sum of Data Driven Conclusion the ratios of 10 CFR 30.72 NSPM-20 Tier I Schedule C ves → Radiological Emergency NSPM-20 Tier I| Quantities × Response Plan Prepared Release NSPM-20 Tier III Factors Applicant Determination exceeds 1 Subject to FAA Concurrence Optional Paths for Applicants → No Fissile, Criticality Hazard Analysis Yes Fertile or Fissionable Prepared Isotopes Present _ NO OPTIONAL:
Device has Comparison made to existing No analyses and quantity limits to potential for determine the maximum potential exposure based on criticality.
RMR information.
Optional Comparison Process LEU Optional Comparison Omitted Fuel Maximum Total exposure Activity shows ≤ 5 potential yes ≤ 100,000 Onboard rem TED to a A2; or, Tier Il or III, Tier III, member of MM ≤ Additional Additional the public. 100,000 Analysis Analysis Needed Needed → No No Tier I, No Analysis Maximum Needed Criticality Safety exposure Analysis Prepared potential Yes Tier II, No Further shows ≤ 25 Analysis rem TED to a Needed member of the public.
NO Radiological Hazard Analysis Prepared High Fidelity Radiological Safety Analysis Prepared Tier Level Determined If Not Already Known Safety Analysis Report Prepared Figure 4 - Nuclear Safety Analysis Flow Chart 32
Launch and Reentry of Space Nuclear Systems AC 450.45-1 33
8.3.2 All applicant-developed nuclear safety analyses for payloads should consider the entire mission lifetime. Depending on mission specifics, the mission lifetime may include:
• Pre-Launch;
• Launch;
• Ascent, Early and Late;
• Suborbital, including staging;
• Orbital, including temporary on-orbit operations;
• Earth escape;
• Earth return, including flyby;
• Reentry; and
• End of Mission (EOM), including disposal.
8.3.3 The mission phases for nuclear space launch should cover all launch vehicle or payload potential for any planned or accidental Earth reentry of nuclear material. For example, Earth return scenarios would include considerations for nuclear material launched to:
• Other planetary bodies capable of a free return trajectory to Earth;
• Earth gravity assist fly-by trajectory; or
• Earth orbit intersecting trajectories where planned or accidental Earth reentry of nuclear material is possible.
8.3.4 If reasonably foreseeable scenarios exist that would pose a safety hazard to the public and environment, the nuclear safety analyses performed for licensing should quantify the radiological risk to the public from that scenario and include it in determining the overall mission risk.
8.3.5 The EOM should include safe disposal of the radionuclide. The long-term storage of spent nuclear fuel on Earth has been a problem since the advent of the nuclear industry (GAO 2021). SNS have disposal options at EOM not available to terrestrial nuclear devices, as summarized in Table 4 of this AC, with varying levels of government review required.7 For example, a disposal option for an on-orbit nuclear reactor that has reached criticality might be to boost it into a high disposal orbit to allow sufficient time for radioactive decay of fission products, which could take hundreds or thousands of years (SPD-6 2020). Failure of the vehicle to boost itself or to eject the hot core into a safe disposal orbit could result in an inadvertent public safety reentry hazard (Gummer, et al. 1980). Alternately, if the core were boosted to escape velocity for disposal, it
7 Because spent nuclear fuel is a significant hazard, the disposal plan is evaluated before licensing the launch of the system, even though the ultimate disposal may be years out. Terrestrial disposal will be high risk for systems that have operated critically.
Launch and Reentry of Space Nuclear Systems AC 450.45-1 34 might pose a reentry risk to future public generations should third-body orbital forces cause an eventual inadvertent return. Nuclear safety analyses take into consideration all of these potential scenarios and calculate the PER for each.
Table 4 – Nuclear Material Disposal Options Disposal Location Possibility of Return to Earth Interplanetary Space, No Free- Return Trajectory to Earth None or Extremely Low Lagrange Point L1, L2 and L3 Extremely Low; L4 and L5 None A Sufficiently High Altitude in Earth Orbit Low within the period of concern for radiation exposure to the public On Earth Will happen
8.4 Space Nuclear System Design.
Whether or not an applicant uses the means of compliance outlined in paragraph 8.3 and Appendix A of this AC, the design and any safety analyses conducted by an applicant will be evaluated by the FAA during the license evaluation process to assess public health and safety. SNS designs satisfy a variety of unique, competing design constraints. The performance guidelines in Appendix B give guidance on space specific performance characteristics the FAA has identified to reduce the baseline risk of the SNS.
8.5 Interagency Nuclear Safety Review Board.
8.5.1 When an applicant prepares a SAR, as detailed in Appendix A of this AC, to show compliance with § 450.45(e)(6), applicants should be aware that SARs prepared for commercial launches are distinctly different than those prepared for government launches in that SARs for a Tier II or Tier III government launch must go through an Interagency Nuclear Safety Review Board (INSRB) evaluation, while a SAR for a commercial launch of any Tier may, at the Secretary of Transportation’s discretion, be evaluated by the INSRB. This distinction is important and streamlines the FAA’s ability to license commercial SNS launch and reentry.
8.5.2 Under NSPM-20, the Secretary of Transportation can request no review, a partial review, or a full INSRB evaluation of the SAR. In these cases, the role of the INSRB will be to review the SAR and supporting nuclear safety analyses, to evaluate the quality of the analyses, and to identify specific gaps. This evaluation is then documented in a safety evaluation report, which may include recommendations for how to improve the analyses. The INSRB recommends approvals, and the FAA issues approvals.
Launch and Reentry of Space Nuclear Systems AC 450.45-1 35
8.5.3 The INSRB information is available at https://sma.nasa.gov/sma-disciplines/nuclearflight-safety. Applicants may consider reviewing the INSRB guidance provided to government agencies seeking to launch SNS and other reports related to nuclear technology and safety.
8.6 A pplication Determination .
8.6.1 If applying for a license, after accepting the application and performing the policy review, safety review, payload review, environmental review, and financial responsibility determination, the FAA makes a licensing determination on the SNS on a case-by-case basis, per §450.45(e)(6). If applying for a payload determination, the FAA issues a favorable payload determination if the applicant has obtained all required licenses, authorizations, and permits and its launch or reentry would not jeopardize public health and safety, safety of property, U.S. national security or foreign policy interests, or international obligations of the United States.
Launch and Reentry of Space Nuclear Systems AC 450.45-1 36 Appendix A. Nuclear Safety Information and Analyses A.1 SCOPE.
An applicant using this AC as a means of compliance to § 450.45(e)(6) or § 450.43(a)(2) should provide to the FAA the information and conduct the analyses in this appendix.
A.2 SNS DEVICE AND MISSION DESCRIPTION.
A.2.1 The following information is foundational to the nuclear safety analyses and ultimately the public safety risks of the SNS mission. The applicant should provide the following information to the FAA such as:
• SNS owner and operator;
• SNS type;
• SNS purpose;
• SNS physical dimensions and weight;
• Structural design of SNS components;
• SNS physical barriers to radioactive release;
• SNS instrumentation, monitoring, and control system characteristics;
• SNS fuel design;
• SNS orbital parameters for parking, transfer, and final orbits;
• Hazardous material quantities, including the radioactive material via the RMR;
• Mission stages for the SNS;
• Intended SNS operations during the entire mission;
• Delivery point in flight at which the SNS will no longer be under the launch licensee’s control;
• Methods to prevent and terminate criticality during launch and reentry, as applicable;
• Shielding design and materials used;
• Decay heat generation rates expected during launch or reentry, as applicable;
• Decay heat removal methods, as applicable;
• Decay heat removal capability, as applicable;
• Signal paths from SNS to the operator;
• SNS control system design and operational parameters; and
• SNS and host spacecraft software design, configuration control, and performance.