ML22081A057

Developing a Regulatory Framework for Commercial Fusion Energy Systems - NRC Public Meeting March 23, 2022

ML22081A057
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Issue date:	03/23/2022
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Developing a Regulatory Framework for Commercial Fusion Energy Systems NRC Public Meeting March 23, 2022

Time Topic Speaker 1:00 pm Introductions NRC 1:15 pm Identification and Characterization of Dr. Patrick White Fusion Hazards 2:15 pm Overview of Fusion Industry Association Andrew Holland, Fusion Member Company Commercial Device Industry Association &

Agenda Operational & Off-Normal Safety Case Derek Sutherland, CT Fusion 3:30 pm Break 3:40 pm Overview of Tritium Handling Systems Tyler Ellis, Commonwealth Fusion Systems 4:25 pm Supplemental Discussion of the Helion David Kirtley, Helion Device Safety Case Energy 4:55 pm Question and Answer Period 5:30 pm Adjourn 2

Identification and Characterization of Hazards for the Regulation of Commercial Fusion Reactors Patrick White (r.patrick.white@gmail.com)

Nuclear Regulatory Commission Public Meeting - March 23, 2022 Meeting Topic: Developing Options for a Regulatory Framework for Commercial Fusion Energy Systems 3

Development of regulation for fusion is challenging due to technology diversity and early stage of design Confinement Methods Fusion Reactions Fusion Fuel Cycles Power Conversion Cycle Facility Size 4

First-principles approach to regulation development can minimize or clarify a priori assumptions for novel activities Does an activity need to be regulated?

First-principles based licensing facilitates:

How is successful regulation defined?

• Sound basis for regulatory regimes

• More consistent regulatory oversight How do we evaluate

• Appropriate regulatory requirements regulatory compliance?

What framework is used to ensure compliance?

5

Commercial fusion regulation can be examined using a first principles paradigm to evaluate different regulatory options Does an activity need What are the hazards of to be regulated? commercial fusion?

How is successful regulation How do we define acceptable defined? hazard limits for fusion?

How do we evaluate How do we evaluate fusion regulatory compliance? facilities for licensing?

What framework is used to What regulatory frameworks are ensure compliance? appropriate for fusion?

6

Commercial fusion regulation can be examined using a first principles paradigm to evaluate different regulatory options Does an activity need What are the hazards of to be regulated? commercial fusion?

How is successful regulation How do we define acceptable defined? hazard limits for fusion?

How do we evaluate How do we evaluate fusion regulatory compliance? facilities for licensing?

What framework is used to What regulatory frameworks are ensure compliance? appropriate for fusion?

7

A generalized mental model for hazards and consequences facilitates qualitative understanding of hazardous activities

• Hazard: How much hazardous material is released/what is the hazard?

• Exposure: How much hazardous material/hazard affects people/property?

• Impact: What is the correlation of the exposure to consequences?

8

Detailed expansion of a generalized hazards and consequence model enables quantitative assessment Factors Example Factors Example Factors Example Total material or Meteorological, Correlations Exposure-Hazard inventory material vulnerable geographic, location between exposure Dispersion conditions consequence to release factors that control and exposure relationships dispersion consequences Hazard inventory Fraction of material released released Duration of exposure, Population Exposure-dose physiological factors Exposed population distribution and Hazard inventory Time, location, form conditions that affect total characteristics characteristics that release conditions of the release exposure affect consequences 9

Identification and general characterization of hazards is fundamental to a first-principles approach to regulation Factors Example Factors Example Factors Example Total material or Meteorological, Correlations Exposure-Hazard inventory material vulnerable geographic, location between exposure Dispersion conditions consequence to release factors that control and exposure relationships dispersion consequences Hazard inventory Fraction of material released released Duration of exposure, Population Exposure-dose physiological factors Exposed population distribution and Hazard inventory Time, location, form conditions that affect total characteristics characteristics that release conditions of the release exposure affect consequences 10

Structured method for assessing fusion hazards enables comparison of diverse technologies at different design stages Characterization Assessment of Identification of Definition of of Hazards and Regulatory Licensing Hazards the Activity Consequences Significance for Fusion 11

Variety of fusion technologies and limited design details makes general definition of fusion hazards challenging Characterization Assessment of Identification of Definition of of Hazards and Regulatory Licensing Hazards the Activity Consequences Significance for Fusion Confinement Fusion Facility Size Methods Fuel Cycles Fusion Power Reactions Conversion Cycle 12

Systems engineering focus enables technology-Definition of the Activity independent characterization of fusion energy Function Block Function Commercial Produce net Fusion Power electricity Plant from fusion energy Level 0 System Engineering Model:

Generalized Facility Concept Inputs and Outputs 13

First decomposition of functions characterizes Definition of the Activity general facility operations for a fusion facility Produce heat from Fusion Power fusion reactions System Commercial Produce net Convert heat into Balance of Plant Fusion Power electricity from fusion energy electricity System Plant Level 0 System Engineering Model Support facility Auxiliary operations Support System Level 1 System Engineering Model 14

Definition of the Activity Fundamental relationships between function blocks and external inputs emerge Level 1 System Engineering Model:

Generalized Plant Functions and Interfaces 15

Second decomposition of functions provides a Definition of the Activity simple conceptual model for a fusion facility Control, contain, and Fusion Reactor sustain fusion reactions System Provide fuel for Fusion Reactor fusion reactions Fueling System Fusion Power Produce heat from System fusion reactions Convert fusion reaction Fusion Energy byproducts into heat Extraction System Level 1 System Engineering Model Process/recycle Fusion Exhaust exhaust/byproducts Processing System from fusion reactions Level 2 System Engineering Model 16

Definition of the Activity Model structure illustrates interactions of fusion systems and balance of plant systems Level 2 System Engineering Model:

High Level System Functions and Interfaces 15

Third decomposition of functions approaches limit Definition of the Activity of form-independent characterization of fusion Control fusion reactions Plasma Control System in the plasma Actively confine fusion Plasma Confinement reactions and plasma System Control, contain, and Fusion Reactor sustain fusion System reactions Passively contain fusion Fusion Reactor Vessel reactions, plasma, and System byproducts Level 2 System Engineering Model Maintain fusion reactor Fusion Reactor Vessel internal conditions Environmental System Level 3 System Engineering Model 18

Definition of the Activity Level 3 System Engineering Model provides detail functional diagram for commercial fusion facility Level 3 System Engineering Model:

Plant System or Component Functions and Interfaces 19

Definition of the Activity Portion of system engineering model shows emergent detail and interactions within commercial fusion facilities Portion of Level 3 System Engineering Model 20

Development of technology-specific models enables Definition of the Activity better characterization of fusion facility hazards Control fusion reactions Control fusion reactions Plasma Control System Plasma Control System in the plasma in the plasma Plasma Confinement Actively confine fusion Actively confine plasma Magnetic Confinement System reactions and plasma using magnetic fields System Passively contain fusion Passively contain fusion Fusion Reactor Vessel reactions, plasma, and reactions, plasma, and Torus / Vacuum Vessel System byproducts byproducts at pressure Maintain torus and Fusion Reactor Vessel Maintain fusion reactor Torus Environmental vessel operating Environmental System internal conditions Control System conditions D-T Tokamak Technology Specific Level 3 Level 3 System Engineering Model System Engineering Model 21

Definition of the Activity Technology-specific model enables characterization of specific functional systems in fusion facility Portion of D-T Tokamak Level 3 System Engineering Model 22

System engineering, functional decomposition reveal Definition of the Activity relationships and characterization for fusion facility Example: Function Block Function Passively contain fusion reactions, Torus / Vacuum Vessel plasma, and byproducts at pressure Function Block Description

• Physical system that contains includes the torus and vacuum vessel that passively contain the plasma during operation

• Critical system interface between fusion fuel and plasma control related function blocks (inputs), and reactor exhaust and fusion energy capture related function blocks (outputs) 23

System engineering and functional decomposition Definition of the Activity facilitates design-independent facility characterization Important Limitations System Engineering Model Levels

• Assumptions on

• Level 0 - Generalized Facility C oncept Inputs and O utputs electricity production

• Level 1 - Generalized Plant Functions and Interfaces

• Level 2 - Hig h -Level System Functions and Interfaces

• Assumptions on

• Level 3 - Plant System or C omponent Functions and Interfaces thermodynamic cycle

• Level 3 - Technology-Specific Plant System or C omponents

• General example for technology-specific design 24

Broad hazard description facilitates robust Characterization of Hazards characterization of possible fusion hazards Hazard Identification Categories

• Electrical

• Explosive Material

• Direct Radiation Exposures

• Thermal

• Kinetic (Linear and Rotational)

• Non-ionizing Radiation

• Pyrophoric Material

• Potential (Pressure)

• Natural Phenomena

• Spontaneous Combustion

• Potential (Height/Mass)

• Superconducting Magnets

• O p e n Flame

• Internal Flooding Sources

• Criticality

• Flammables

• Physical

• External Man-made Events

• Combustibles

• Radioactive Material

• Vehicles in Motion

• Chemical Reactions

• Other Hazardous Material Source: Adapted from Department of Energy (DOE) Hazard and Accident Analysis Handbook 25

Characterization of adverse consequence Characterization of Hazards importance focuses evaluation on significant hazards Adverse consequences Human impacts Environmental impacts Economic impacts On-site personnel injuries On-site contamination Production outage

• Air Poor capacity factor On-site loss of employment

• Water Loss of economic viability Off-site community injuries

• Soil Negative image Off-site evacuations Off-site contamination Legal liability Off-site loss of employment

• Air On-site facility damage Psychological effects

• Water Off-site property damage

• Soil Off-site property value loss Source: Adapted from Department of Energy (DOE) Guidelines for Hazard Evaluation Procedures 26

Hazard Consequence Index (HCI) provides a clear ranking system for hazard assessment of a novel system Regulatory Significance Consequence Severity (FCS) x Regulatory Importance (FRI) = Hazard Consequence Index (HCI)

Examp le - Hazard C onsequence Pairs FCS Factor Criteria FRI Factor Criteria Direct Radiation Exposure (Hazard) and High regulatory importance Off-site Evacuations (Consequence):

3 High severity potential 3 (Off-site adverse consequences) F RI = 3 (High regulatory importance)

Medium regulatory importance F C S = 1 (Low severity potential) 2 Moderate severity potential 2 HCI = 3 (On-site adverse consequences)

Low regulatory importance Direct Radiation Exposure (Hazard) and 1 Low severity potential 1 or economic importance Psychological effects (Consequence):

No regulatory or F RI = 3 (High regulatory importance) 0 No potential for consequence 0 economic importance F C S = 3 (High severity potential )

HCI = 9 27

HCI evaluation reveals 4 hazards with high Regulatory Significance severity potential and regulatory importance Top significant regulatory hazards

• Radioactive Material

• Other Hazardous Material

• Explosive Material

• Direct Radiation Exposures 28

Example: Level 3 D-T Tokamak model highlights Regulatory Significant Hazards systems with regulatory significant hazards Top significant regulatory hazards Systems with 4 Hazards

• Radioactive Material Systems with 3 Hazards

• Other Hazardous Material Systems with 2 Hazards

• Explosive Material

• Direct Radiation Exposures Systems with 1 Hazards Systems with 0 Hazards 29

Example: Level 3 D-T Tokamak systems with four Regulatory Significant Hazards regulatory significant hazards are wide ranging Fusion Power Systems Auxiliary Support Systems Torus / Vacuum Vessel Fusion Fuel Preparation System Plasma Fueling System D-T Processing System Plasma Heating System Top significant regulatory hazards D-T Storage System

• Radioactive Material

• Other Hazardous Material Fusion Exhaust Processing System Plant Radiological Maintenance

• Explosive Material Hydrogen Isotope Separation System Radiological Waste Handling System

• Direct Radiation Exposures Torus Cooling, Fusion Breeding Blanket Plant Emission Control Systems Blanket Processing System Effluent Release System Waste Disposal System Torus Vacuum Pumping System Process Fluid Handling System 30

Example: Radiological hazards can be broadly Regulatory Significant Hazards defined the D-T Tokamak Level 3 Model Gases Liquids Solids

• Activated air and

• Liquid activation

• Mobile solid activated materials process gases product (e.g., Be-10) (e.g., erosion/corrosion products)

• Activated plasma

• Liquid aqueous

• Mobile contaminated (including T) materials control gases radioactive products (e.g., erosion/corrosion products)

• Gaseous blanket/ (H 2 O with dissolved

• Fixed solid activated materials structural activation radioisotopes, HTO) (e.g., structural materials) products

• Fixed solid contaminated (including T) materials (e.g., C-14) Plasmas (e.g., structural materials)

• Gaseous tritium

• Plasma radioactive

• Solid tritium metallic compounds and tritiated products (activated (e.g., uranium titride, titanium titride) compounds control gasses)

• Solid frozen tritium compounds (e.g., T 2 )

• Plasma tritium 31

Example: Radiological hazards can be specified Regulatory Significant Hazards and defined for D-T Tokamak Level 3 Model block Radioactive Material Hazards Function Block Function

• Activated plasma control gases

• Gaseous tritium and tritiated compounds Separate unused fusion Fusion Exhaust

• Mobile solid activated materials fuel from other fusion Processing System reactor waste streams (e.g., erosion/corrosion products)

• Mobile contaminated (including T) materials (e.g., erosion/corrosion products) 32

Completion of all steps for specific technology provides insights on potential hazards for commercial fusion Characterization Assessment of Identification of Definition of of Hazards and Regulatory Licensing Hazards the Activity Consequences Significance for Fusion System Model Level Level 3 Increased Level 2 engineering model complexity Level 1

(# Systems)

Level 0 0 20 40 60 33

Next step in regulation development is qualitative binning or technology-specific quantification of specific regulatory hazards Factors Example Factors Example Factors Example Total material or Meteorological, Correlations Exposure-Hazard inventory material vulnerable geographic, location between exposure Dispersion conditions consequence to release factors that control and exposure relationships dispersion consequences Hazard inventory Fraction of material released released Duration of exposure, Population Exposure-dose physiological factors Exposed population distribution and Hazard inventory Time, location, form conditions that affect total characteristics characteristics that release conditions of the release exposure affect consequences 34

Applicant and regulator evaluation of hazards can result in a variety of insights but processes should be efficient and effective Not applicable to technology or design Applicable, quantified, and is not significant for safety or licensing evaluations Applicable, qualitatively assessed and bounded, and is not significant for licensing evaluations Factors Example Applicable, quantified, and is significant for safety or licensing evaluations Total material or Hazard inventory material vulnerable to release Applicable, qualitatively assessed but not bounded, and is significant for safety or licensing evaluations Hazard inventory Fraction of material released released Applicability has not been determined or hazard has Hazard inventory Time, location, form release conditions of the release not been assessed - more information is needed.

35

First-principles approach provides regulators and public repeatable and transparent framework for assessing fusion Does an activity need What are the hazards of to be regulated? commercial fusion?

How is successful regulation How do we define acceptable defined? hazard limits for fusion?

How do we evaluate How do we evaluate fusion regulatory compliance? facilities for licensing?

What framework is used to What regulatory frameworks are ensure compliance? appropriate for fusion?

36

Future discussions can provide additional strategies and insights on first-principles approach to fusion regulation development Does an activity need What are the hazards of to be regulated? commercial fusion?

How is successful regulation How do we define acceptable defined? hazard limits for fusion?

How do we evaluate How do we evaluate fusion regulatory compliance? facilities for licensing?

What framework is used to What regulatory frameworks are ensure compliance? appropriate for fusion?

37

Process for identification of fusion hazards provides basis for regulatory discussions and reviews of commercial fusion facilities Characterization Assessment of Identification of Definition of of Hazards and Regulatory Licensing Hazards the Activity Consequences Significance for Fusion System Engineering Models Not applicable to technology or design

• Technology-independent way to characterize fusion facilities Applicable, quantified, and is not significant for safety or

• Transparent and traceable licensing evaluations process for regulators Applicable, qualitatively assessed and bounded, and is not significant for licensing evaluations Top significant regulatory hazards Applicable, quantified, and is significant for safety or

• Radioactive Material licensing evaluations

• Other Hazardous Material Applicable, qualitatively assessed but not bounded, and is

• Explosive Material significant for safety or licensing evaluations

• Direct Radiation Exposures Applicability has not been determined or hazard has not been assessed - more information is needed. 38

Time Topic Speaker 1:00 pm Introductions NRC 1:15 pm Identification and Characterization of Dr. Patrick White Fusion Hazards 2:15 pm Overview of Fusion Industry Association Andrew Holland, Fusion Member Company Commercial Device Industry Association &

Agenda Operational & Off-Normal Safety Case Derek Sutherland, CT Fusion 3:30 pm Break 3:40 pm Overview of Tritium Handling Systems Tyler Ellis, Commonwealth Fusion Systems 4:25 pm Supplemental Discussion of the Helion David Kirtley, Helion Device Safety Case Energy 4:55 pm Question and Answer Period 5:30 pm Adjourn 39

40 Offsite Impacts of Fusion Normal Operation / Off-Normal Shutoff NRC Public Meeting March 23, 2022 41

FIA Membership 42

Outline Andrew Holland, CEO, Fusion Industry Association

• FIA Survey Overview Derek Sutherland, CEO, CTFusion

• Normal Operation of Fusion Energy Systems

• Off-Normal Shutoff of Fusion Energy Systems

• Summary, Questions 43

FIA Survey Overview 44

FIA Survey Overview Survey questions focused on three primary areas:

• Fusion neutron shielding, and site boundaries

• What level and type of shielding will be used?

• What is the current anticipated distance to site boundary for a planned commercial facility?

• Tritium usage (if any)

• How much tritium is in the device at any one time?

• How much tritium is in the vacuum chamber at any time?

• Dust generation

• What activated dust may accrue in vacuum?

• How much will be removed during regular cleanout?

45

FIA Survey Overview

• Data collected from members during January 2022

• All U.S. FIA members with well-developed technological designs provided responses

• These numbers were compiled and used to calculate the offsite impacts of commercial fusion technology

• Calculations and scenarios focused on highest potential impact

• Only considered safety systems which are universal to all commercial fusion developers 46

FIA Survey Overview -

General Impressions There is no generic fusion power plant, but some common features

• FIA members vary greatly in anticipated size, ranging from small devices aiming for 1 kWe power production up to 350 MWe.

• FIA members also vary in fusion technology approach (magnetic, inertial, magneto-inertial) and fuel type (D-T, D-D, D-3He, p-11B)

• HOWEVER, there are no plans in the FIA for anything in the GWe sizes being predicted by international DEMO designs.

• None will require active cooling after shutdown

• The designs, fuel sources, first walls materials, and shielding anticipated in fusion power plants varies as well, but commercial fusion facilities share some common features.

• From a risk-informed perspective, all of the conceived fusion reaction types or fuel choices present risks that can be appropriately regulated under Part 30 regulations 47

Moving on an Accelerated Timeline There is a common development timeline FIA Members are moving into fusion pilot plants by the late 2020s

• FIA members are moving at an accelerated rate, relevant to the White Houses Bold Decadal Vision to Accelerate Fusion Energy announced at a summit on March 17.

• FIA members anticipate applying for a commercial operation license as early as 2026, with more coming 2027-2030 48

FIA Survey Results Fusion neutron shielding, and site boundaries For most fusion power plants, the neutrons are the energy output, so capturing these neutrons are an economic imperative. For those not captured, shielding will protect workers and the general public Q: What shielding will be used to minimize offsite exposure and worker dose?

The need for shielding depends on several factors beyond just neutron flux, especially the design of the blanket.

A: Liquid metal or molten salt blanket, concrete shield, boron carbide, polyethylene, water, graphite, metal hydrides, tungsten Q: What is the anticipated site boundary distance?

A: Site boundaries have generally not been determined, and will depend on the shielding implemented. It is possible that site boundaries would be determined by standard industrial offsets like those at similarly-sized gas turbine generators.

Q: What is the anticipated fenceline dose?

A: All are targeting a fenceline dose of very close to zero, well below the 10 CFR Part 20 limits.

49

FIA Survey Results Tritium usage Q: How much tritium is in the commercial fusion power plant at any one time?

A: 0 - 90 g Q: How much tritium is in the fusion vacuum chamber at any time?

A: 0 - 0.1 g

• Note that this does not account for the amount of tritium that may be stored on site, but in a facility separate from the power plant. These facilities would already be regulated under existing 10 CFR Part 30 or relevant agreement state materials regulations.

50

FIA Survey Results Dust generation Q: What are the isotopes of activated dust that may accrue in the vacuum?

Dust is relevant to fusion power plants that have solid walls, and the types of dust that may accumulate are dependent on the material choice for the walls. Since new first wall-materials will likely be developed for use in commercial fusion systems, these calculations will change as new alloys are developed.

A: Isotopes vary design-by-design and are driven by materials choices. Representative isotopes in fusion power plants include: O, Si, Hf-178m, Ta-179, Ta-182, W-181, W-183, W-185, W-187, Re-186, Re-187, Re-188 Other aneutronic fuels will have different portfolio of activated materials in trace amounts.

Q: What is the maximum amount of dust that can accumulate prior to a scheduled outage for cleanout?

This question is dependent upon reactor size, operation, materials, scenarios, and many other variables and is difficult to normalize.

A: Most companies have not yet done the calculations, and the answer will be determined by operational needs, but estimates are well below 100g.

51

Normal Operation of Fusion Energy Systems 52

All fusion systems consume light elements and produce slightly heavier ones, releasing usable energy in the process 2H + 3H 4He (3.5 MeV) + 1 n (14.1 MeV)

D-T 2H + 2H 3H (1.01 MeV) + 1 p (3.02 MeV)

D-D 3He (0.82 MeV) + 1 n (2.45 MeV)

D-3He 2H + 3He 4He (3.67 MeV) + 1 p (14.68 MeV) 1p + 11B 3 4He (8.7 MeV) p-11B Zero usage of special nuclear materials (i.e. uranium, plutonium) in fusion energy systems and requires high temperatures for relevant reaction rates 53

Energy accounting defines requirements for net-gain operation, burning and ignited fusion plasmas Conservation of Energy: Energy cannot be created or destroyed, so sources of energy must equal losses of energy from a system for the energy content to stay the same.

Sources of Energy = Losses of Energy Pfusion + Pinput = Plight + Pcond.

Sources of energy Pfusion is the fusion power density in the fusing plasma Pinput is the external heating power supplied to the plasma Losses of energy Plight is the loss of energy from the plasma as light (i.e. Bremsstrahlung light)

Pcond is the loss of energy from the plasma as heat (i.e. thermal conduction 3nT/E) 54

Net-gain operation is required for all commercial fusion energy systems, burning plasmas are plasmas with self-heating at least equal to input power Self-Heating Pself Note: This is the self-heating power Fusion Power for charged fusion products redepositing their energy into the Pfusion n2 <v> Erec V plasma after being created by fusion n is plasma density, <v> is fusion reaction rate, (i.e. alpha particles for DT fusion) Erec is the fusion energy released per reaction, and V is the fusing plasma volume Sub-ignited, Net-gain Operation Fusion Power Output > Q > 1, Pinput > 0 Power Input Pinput Fusion Plasma Pfusion= QPinput Burning DT Plasma Operation Fusion Fuel Fusion Product Input Exhaust

> Q > (5Pself /Pinput) > 5 Vacuum Vessel (VV) Pself / Pinput > 1 Net-Gain: making more fusion power/energy (Pfusion) than the input power/energy (Pinput) required to make it happen - Q = Pfusion/Pinput > 1 New fusion fuel must be added and fusion products removed to maintain Pfusion > 0, otherwise fusion power shuts off All fusion approaches can only fuse a small amount of fusion fuel in the plasma at any time, otherwise fusion power shuts off 55

Ignited fusion plasmas are the special case when enough self-heating power Pself is made to balance losses, but does not change fusion physics safety Ignited Operation: Q = Pfusion/Pinput = because Pinput = 0 (not Pfusion = )

Q=

Self-Heating Pself Self-heating is Q=1 Peak nTE [keV-s/m3]

enough Fusion Power Output Power Input Pinput Fusion Plasma Pfusion Graphic: S.E.

Wurzel and S.C.

Hsu, Fusion Fuel Fusion Product https://arxiv.org/

Input Exhaust pdf/2105.10954.p df Vacuum Vessel (VV)

No external input power is required to keep the system running in ignition, but fuel input, exhaust, and fusion physics is the same as sub-ignited operation and does not enable a nuclear chain reaction Most fusion concepts plan for sub-ignited, net-gain > Q > 1 commercial fusion systems 56

Fusion fuel inventory in all fusion systems at any time is very small, and cannot be arbitrarily increased without system shutting off Fusion Systems Fission Systems (Requires high plasma temperatures) (Can run at room temperature)

Fission fuel inventory Fission product inventory Pfusion Months of Fusion fuel input Fusion exhaust operation Converts fuel to exhaust Fusion systems have small fuel inventories, and high Fission systems have high fuel inventories and are low throughput demanding constant fuel input and exhaust for throughput. All fuel needed for total energy release for months of system to not shut off. operation is present at start.

Suddenly introduction too much fusion fuel causes the system Slow release of fission energy over time is required for safe to shut off because of rapid plasma cooling operation.

Fusion fuel is converted into exhaust (i.e. helium) and is not a Fission fuel is converted into fission products by a nuclear chain nuclear chain reaction (the concept of criticality does not reaction (the concept of criticality does apply).

apply). 57

Blankets and Shielding Mitigates Offsite Radiation From Fusion Energy Production Filtration/Detritiation Building Walls

• Key contributor to potential offsite impact is radiation leaving the device: neutrons and gamma Shielding rays Blanket* Vacuum Vessel (VV)

• Neutron and gamma ray doses are well mitigated by both blanket and shielding

• Multiple levels of shielding would be used: Fusion Plasma

• Self-shielding: The fusion device itself and ancillary 3H gas, 3H systems, such as the blanket, would absorb most deposited on neutrons VV, activated

• Additional shielding: Remaining neutrons and dust gammas would be shielded using other common materials (e.g., metal hydrides, concrete, etc.)

Neutrons

• Required shielding design and levels is determined Blanket Vessel (BV) Gammas in a similar manner to other technologies licensed under a materials-framework (e.g., accelerators)

• Note: Blankets are used to slow down DT neutrons to make heat and contain lithium to make tritium for fuel on-site. Systems that Description. Dose due to fusion neutrons and gammas, which are use other fusion fuel cycles (D-3He and p-11B) will have different mitigated by the use of blankets and/or shielding design requirements.

Offsite Impact. << 10 mrem/year during normal operations 58

Metal hydrides are exceptional fast neutron and gamma shields A combination of high-Z (for gamma) and low-Z (for neutron) shielding is most efficient Water (H2O) is also very good for neutron shielding because it is composed of light elements (low-Z)

Concrete also is very effective at shielding both neutron and gamma emissions Effective and already in-use shielding solutions are available to mitigate impacts of neutron and gamma Graphic: T. Hayashi, Joul. Nucl. Mat. 386-388 (2009), 119-121, https://doi.org/10.1016/j.jnucmat.2008.12.073 emissions from fusion systems 59

Concrete is another example of highly effective neutron and gamma shielding Calculation using MCNP6.2

- Isotropic neutrons in a 1-cm spherical source

- Neutrons are 14.1 MeV (from DT fusion) at 1018 neutron/sec

• Calculation to right uses an

- 5-m-radius sphere of concrete as an example anticipated neutron production rate - Existing accelerator and medical systems use 2-5 m concrete shielding from a commercial fusion device - Calculation of both neutron and gamma (secondary) dose Dose

• As shown, simple concrete shielding [rem/hr]

can reduce the dose to well-below regulatory limits

• This calculation does not consider any self-shielding, such as from a blanket system that will capture the majority of neutrons.

neutron photon 60

Activated dust generation from fusion operations Neutron activation of solid VV materials and plasma/fusion product interactions with the solid VV during normal operations can generate dust Dust is routinely removed during maintenance cycles, but can be released from VV during particular off-normal shutdown events to be considered in this presentation Activated dust quantities and composition are largely driven by material choices and fusion system specifics Normal Operations Vacuum chamber is routinely cleaned; activated dust is removed Fusion plasma/neutron Fusion neutrons activate reactions loosen wall wall materials materials, creating dust Off-Normal Shutoff Activated dust could be released from VV during off-normal shutoffs 61

Off-Normal Shutoff analysis to follow will focus on tritium usage and activated dust within the vacuum vessel Filtration/Detritiation

• Tritium can be present in the plasma Building Walls dependent on the fusion fuel cycle of choice Puncture in VV

• Tritium can be deposited on the wall, which is typically the majority of the tritium within 3H gas, 3H the vacuum vessel deposited on VV, activated dust

• All off-normal events considered assume a full puncture of the vacuum vessel such that it is open to air within the building Vacuum Vessel (VV)

• A puncture of a vacuum vessel immediately halts all fusion reactions and corresponding neutron production for all fusion approaches Description. Dose due to fusion neutrons and gammas, which are mitigated using blankets and/or shielding Offsite Impact. << 10 mrem/year during normal operations 62

Off-Normal Shutoff of Fusion Energy Systems 63

Key Concepts for Off-Normal Shutoff Scenarios

• Fusion can be stopped at any time and is not a nuclear chain reaction (no risk of supercriticality)

• Off-normal conditions generally stop fusion, which stops neutron generation

• Any remaining emissions are gamma from activated materials at a much lower level than normal operations

• No risk of runaway chain reactions like in fission reactors, with small amount of fuel able to be fused at any time

• No need for active cooling systems in order to cool down components when fusion is stopped like in fission systems

• Accident scenarios are bounded by the releasable inventory of radionuclides at shutdown

• Similar system to other materials facilities like accelerators .

• Managing a fixed inventory of radionuclides is simpler than fission systems

• The fusion device itself is not the hazard during an accident scenario

• Analysis in this presentation focuses on releasable material within the vacuum vessel, not independent tritium management systems

• Important to consider independent tritium management systems in future facility licensing, but already addressed within a Part 30 construct 64

Radionuclide Release Consideration for Off-Normal Shutoff Scenarios

• Tritium Release

• Scenarios focus on the release of tritium oxide in the form of tritiated water (HTO)

• Tritium oxides are of greater importance for calculating doses than elemental tritium (HT),

and correspondingly HTO is the focus of this analysis

• A conservative assumption of 10% conversion of released tritium to tritium oxides is used, consistent with previous analyses by Los Alamos National Laboratory (LANL)* and used by the UKAEA for JET licensing**

• Activated Dust Release

• Dust from plasma-facing components that have activated and eroded

• Equivalent to small amounts of low-level radioactive waste

• Material choices for plasma-facing components significantly impact quantity of dust generation and radionuclide composition

• P.S. Ebey, CONVERSION OF TRITIUM GAS INTO TRITIATED WATER (HTO): A REVIEW WITH RECOMMENDATIONS FOR USE IN THE WETF SAR, LA-UR-01-1825, Los Alamos National Laboratory (2001).

• • A. Bell, "The Safety Case for JET D-T Operation," JET-P, (1999).

65

Off-Normal Shutoff - Safety Systems Considered

• Only systems that will be universal among FIA members were considered to ensure a conservative analysis that is widely applicable to FIA members

• Additional safety systems and features unique to each fusion system design must be considered to more accurately reflect inventory release during off-normal operation Universal systems considered in analysis Building Walls Containing Fusion Device The outer walls of the building confine tritium to exit through designated subsystems The assumed building wall height is 10 m Filtration and Detritiation Systems and Potential Use of Stacks Building exhaust is passed through filters and/or detritiation subsystems The use of a stack to increase release height of radionuclides (all scenarios in this presentation considered use 10 m release height, but taller stacks could be used) 66

Off-Normal Shutoff & Tritium: History

• NRC has previously evaluated historical accidental releases of tritium from Part 30/40/70 licensees

• Previous accidents include:

• 50 g tritium release through a stack at Savannah River Laboratory (1974)

• 30 g tritium release at American Atomics Corp (1978)

• NRC found no evidence that any accident caused an effective dose equivalent to any offsite person more than 10 mrem (well below the public dose limit 100 mrem/yr)

• Provides real-world context for scenarios considered for this presentation 67

HotSpot Code from LLNL to Calculate Release Effects of Interest

• HotSpot provides a set of software tools for evaluating the impact of incidents involving airborne radionuclides

• Models for near-surface releases, short-range (< 10 km), and short-term release durations (< 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />) with a variety of atmospheric conditions

• Provides a conservative estimate of radiation effects

• Quantity of interest: total effective dose equivalent (TEDE), the sum of:

• External dose in the first four days (DDE)

• Internal dose over 50 years (CEDE)

• Tritium Release (HTO) dispersion model is used

• The HotSpot default receptor height, breathing rates, quality factors, and deposition velocities are used o S.G. Homann, F. Aluzzi, HotSpot Health Physics Code Version 3.0 Users Guide, National Atmospheric Release Advisory Center, Lawrence Livermore National Laboratory, LLNL-SM-636474, (2014).

o US DOE, Software Evaluation of HotSpot and DOE Safety Software Toolbox Recommendation, Office of Health, Safety and Security, US Department of Energy, DOE/HS-0003, (2007).

68

Total Effective Dose Equivalent (TEDE) varies with released HTO quantity, height, and atmospheric conditions TEDE v. HTO Released TEDE v. Release Height Release of tritiated water (HTO) is directly proportional to the TEDE Increasing release height using stacks can significantly reduce TEDE TEDE 1 km downwind versus quantity of HTO released. Assumes 1 m/s wind speed, F-grade stability, and 10-m release height.

TEDE 1 km downwind versus release height. Assumes 1 m/s wind speed, F-grade stability, and 0.15 g of HTO released.

TEDE v. Wind Speed and Atm. Stability Higher wind speeds and lower atmospheric stability (A F) tends to decrease TEDE For a given set atmospheric conditions, minimize the quantity of HTO released and increase release height to reduce the TEDE TEDE 1 km downwind as a function of windspeed for atmospheric stabilities A-F. Assumes 10-m release height and 0.15 g HTO released.

(I). Conservative windspeed to use in accident analysis according to NUREG-1140.

(II). Conservative windspeed to use in chemical accident analysis according to EPA (40 CFR 68.22(b)).

(III). Average windspeed in Phoenix, AZ.

(IV). Average windspeed in Boston, MA. 69

Assumptions for Off-Normal/Accident Scenarios Device contains 100 mg of tritium gas within the VV and Filtration/Detritiation 50 g of tritium deposited on VV wall at shut off Building Walls 3H gas and 30% of A puncture in the VV results in air rushing into chamber Puncture 3H from walls (unlike a pressurized system), and only a portion of the in VV tritium leaves the chamber (70% remains embedded in the 10% conversion of VV walls) 3H gas, 3H 3H to HTO deposited on Of the tritium leaving the VV, the conservative assumption VV, activated is a 10% conversion to HTO dust Blanket, shielding, and additional structural components and subsystems not considered in this conservative analysis Vacuum Vessel (VV) o Dept. for Business, Energy & Industrial Strategy, Towards Fusion Energy: The UK Governments proposals for a regulatory framework for fusion energy, Presented to Parliament by Sec. of State for Bus., Energy, and Industrial Strategy by Command of Her Majesty, (2021).

o Fusion Safety Authority, Technology Report - Safety and Waste Aspects for Fusion Power Plants, UKAEA, UKAEA-RE(21)01, Issue 1, (2021).

o Radiation (Emergency Preparedness and Public Information) Regulations (REPPIR), (2019).

o P. Ebey, "Conversion of Tritium Gas into Tritiated Water (HTO): A Review with Recommendations for use in the WETF SAR" LA-UR-01-1825.

o A. Bell, "The Safety Case for JET D-T Operation," JET-P, (1999). 70

Analysis Results for Accident Scenario 1 Filtration/Detritiation

Description:

VV is punctured, but building walls Building Walls and filtration and/or detritiation systems remain intact Puncture 3H gas and 30% of 3H from walls

• All tritium gas and 30% of tritium on wall leaves the VV in VV

• Of the tritium leaving VV, 10% is converted to HTO 10% conversion of 3H 3H to HTO gas, 3H

• All released HTO exits through filtration/detritiation system deposited on and stack VV, activated dust Offsite Impact : < 0.1 mrem The United Kingdom Atomic Energy Authority calculated a 0.01% - 0.001%

probability of this level of accident occurring in one year, using the REPPIR 2019 approved code of practice. Vacuum Vessel (VV) o Dept. for Business, Energy & Industrial Strategy, Towards Fusion Energy: The UK Governments proposals for a regulatory framework for fusion energy, Presented to Parliament by Sec. of State for Bus., Energy, and Industrial Strategy by Command of Her Majesty, (2021).

o Fusion Safety Authority, Technology Report - Safety and Waste Aspects for Fusion Power Plants, UKAEA, UKAEA-RE(21)01, Issue 1, (2021).

o Radiation (Emergency Preparedness and Public Information) Regulations (REPPIR), (2019).

o P. Ebey, "Conversion of Tritium Gas into Tritiated Water (HTO): A Review with Recommendations for use in the WETF SAR" LA-UR-01-1825.

o A. Bell, "The Safety Case for JET D-T Operation," JET-P, (1999). 71

Analysis Results for Accident Scenario 2 10% HTO leakage

Description:

VV is punctured, building walls and to environment filtration and/or detritiation are damaged such that Filtration/Detritiation there is 10% leakage of HTO Building Walls

• All tritium gas and 30% of tritium on wall leaves the VV 3H gas and 30% of Puncture 3H from walls

• Of the tritium leaving VV, 10% is converted to HTO in VV

• 10% of HTO is released into the environment at a release 10% conversion of height of 10 m (height of building) 3H 3H to HTO gas, 3H deposited on HTO Emitted = 0.15g VV, activated

• (0.1 g + (.3)(50 g))(.1)(.1) = 0.15 g dust

• (3H Gas + (% off wall)(3H on wall))(% to HTO)(% leak) = HTO emitted Offsite Impact: < 40 mrem Less than the 100 mrem annual public dose limit to the public Vacuum Vessel (VV)

The United Kingdom Atomic Energy Authority calculated a one in a million in one year probability of this level of accident occurring in one year, using the REPPIR 2019 approved code of practice o Dept. for Business, Energy & Industrial Strategy, Towards Fusion Energy: The UK Governments proposals for a regulatory framework for fusion energy, Presented to Parliament by Sec. of State for Bus., Energy, and Industrial Strategy by Command of Her Majesty, (2021).

o Fusion Safety Authority, Technology Report - Safety and Waste Aspects for Fusion Power Plants, UKAEA, UKAEA-RE(21)01, Issue 1, (2021).

o Radiation (Emergency Preparedness and Public Information) Regulations (REPPIR), (2019).

o P. Ebey, "Conversion of Tritium Gas into Tritiated Water (HTO): A Review with Recommendations for use in the WETF SAR" LA-UR-01-1825.

o A. Bell, "The Safety Case for JET D-T Operation," JET-P, (1999). 72

Analysis Results for Accident Scenario 3

Description:

VV is punctured, building walls and 100% HTO leakage filtration and/or detritiation are damaged such that to environment there is 100% leakage of HTO Filtration/Detritiation Building Walls

• All tritium gas and 30% of tritium on wall leaves the VV

• Of the tritium leaving VV, 10% is converted to HTO 3H gas and 30% of Puncture 3H from walls

• 100% of HTO is released into the environment at a release in VV height of 10 m (height of building) 10% conversion of 3H 3H to HTO gas, 3H HTO Emitted = 1.5g

• (0.1 g + (.3)(50 g))(.1)(1) = 1.5 g deposited on

• (3H Gas + (% off wall)(3H on wall))(% to HTO)(% leak) = HTO emitted VV, activated dust Offsite Impact < 401 mrem

• Maximum dose occurs at 0.47 km Less than the 1000 mrem emergency

• Dose at 1.00 km = 230 mrem planning threshold Vacuum Vessel (VV)

The United Kingdom Atomic Energy Authority calculated a one in ten million in one year probability of this level of accident occurring in one year, using the REPPIR 2019 approved code of practice o Dept. for Business, Energy & Industrial Strategy, Towards Fusion Energy: The UK Governments proposals for a regulatory framework for fusion energy, Presented to Parliament by Sec. of State for Bus., Energy, and Industrial Strategy by Command of Her Majesty, (2021).

o Fusion Safety Authority, Technology Report - Safety and Waste Aspects for Fusion Power Plants, UKAEA, UKAEA-RE(21)01, Issue 1, (2021).

o Radiation (Emergency Preparedness and Public Information) Regulations (REPPIR), (2019).

o P. Ebey, "Conversion of Tritium Gas into Tritiated Water (HTO): A Review with Recommendations for use in the WETF SAR" LA-UR-01-1825.

o A. Bell, "The Safety Case for JET D-T Operation," JET-P, (1999). 73

Use of stacks is a common approach to further reduce offsite impacts from radionuclide releases TEDE v. Release Height The accident scenarios considered in this presentation all used a release height of 10 m (release through the top of the building containing the fusion device)

The use of stacks to increase release height can reduce offsite total effective dose equivalent (TEDE) considerably Increasing stack height from 10 m to 30 m can TEDE 1 km downwind versus release height. Assumes reduce TEDE by more than a factor of 10 conservative 1 m/s wind speed, F-grade stability, and 0.15 g of HTO released.

74

Tritium release accident scenario conclusions

• When VV is punctured, fusion reactions immediately stop in all cases

• Machine is not the hazard

• Neutron production stops

• The tritium inventory is fixed

• Variety of commonly used safety systems ameliorates accident risks to the public health and safety

• Analysis is conservative and < 0.1 mrem < 40 mrem 100 mrem < 401 mrem 610 mrem 1000 mrem demonstrates that FIA members are below the emergency (evacuation) 310 mrem planning threshold of 1000 mrem 75

Calculations of the contribution from dust to offsite impacts is underway by FIA members

• First wall material choices and system specifics will affect the quantities of dust generation and composition of activated dust in fusion systems

• Additional contributions to potential offsite impacts are expected to be low compared to tritium releases considered in the scenarios in this presentation

• Additional information will be provided by FIA members on the contributions of activated dust once analyses are completed

• Use bounding case of JET and ITER using a tungsten wall to estimate activated dust accumulation contributions to radionuclide inventory of the system 76

Bounding case for dust generation using JET data and ITER analyses scaled to high-end of FIA survey range Use data from JET and for an ITER-like wall as bounding case for dust generation Amount of dust on wall obtained from JET experimental analysis

• 1.4 g per 19.1 hours1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> of plasma operation - 1.8 g of dust per day of plasma operation Use amount of activation per gram of dust from ITER study (not all dust is activated) and scale down to high-end of FIA scale Perform analysis at distance where dose is maximized, consistent with the other conservative analyses in this presentation Assuming a quarterly cleanout of dust, providing a maximum of ~156 g of dust in the vacuum vessel at any time 77

With a maximum inventory of 156 g of dust at any time, additional contribution to offsite impact is small (< 10%)

Accident Scenario Previous Offsite Additional Maximum Offsite Maximum Maximum TEDE Contribution to TEDE TEDE w/ Dust

1. 1 < 0.1 mrem < 0.1 mrem < 0.1 mrem

1. 2 < 40 mrem < 3.8 mrem < 43.8 mrem

1. 3 < 401 mrem < 38 mrem < 439 mrem Note: analysis conservatively assumes all dust leaves vacuum vessel, unlike the 30% release used for tritium.

Contribution to offsite TEDE with the inclusion of released activated dust is small (< 10%) and does not change the outcome of considered scenarios with respect to annual public dose (100 mrem) and emergency planning (1000 mrem) thresholds 78

Summary

• Fusion systems have zero usage of special nuclear materials, and fusion is not a nuclear chain reaction

• Normal fusion operations can produce neutrons and gamma rays, which can be effectively shielded using currently in-use materials

• Off-normal events result in automatic shutdown of fusion reactions, and cannot lead to a meltdown

• Tritium releases in credible accidents are below the annual dose limit to the public of 100 mrem, and in all scenarios are below emergency planning threshold of 1000 mrem

• Refined dust analyses are underway by FIA members, but contribution to offsite impact is expected to be low compared to tritium

• The offsite impacts are akin to those of byproduct materials licensees, not of fission reactors that use special nuclear materials and are based on nuclear chain reactions

• Offsite impact risk for fusion is low relative to utilization facilities and do not support a design basis/beyond design basis construction 79

Time Topic Speaker 1:00 pm Introductions NRC 1:15 pm Identification and Characterization of Dr. Patrick White Fusion Hazards 2:15 pm Overview of Fusion Industry Association Andrew Holland, Fusion Member Company Commercial Device Industry Association &

Agenda Operational & Off-Normal Safety Case Derek Sutherland, CT Fusion 3:30 pm Break 3:40 pm Overview of Tritium Handling Systems Tyler Ellis, Commonwealth Fusion Systems 4:25 pm Supplemental Discussion of the Helion David Kirtley, Helion Device Safety Case Energy 4:55 pm Question and Answer Period 5:30 pm Adjourn 80

CFS Technology Overview Tyler Ellis, Ph.D.

81 3/21/2022 Copyright Commonwealth Fusion Systems 8

Fusion energy is sustained by self-heating and recycled neutrons Energy Before (MeV) Energy After (MeV)

~ 0.01 14.1

~0.01 3.5 Fuel in plasma state: T=10 keV ~ 100 million C 3/22/2022 Copyright Commonwealth Fusion Systems Credit: Prof. Dennis Whyte, MIT 82

Fusion energy is sustained by self-heating and recycled neutrons Energy Before (MeV) Energy After (MeV)

~ 0.01 14.1

~0.01 3.5 He charged product heats the D-T through plasma collisions He is highly stable, cannot undergo further reactions 3/22/2022 Copyright Commonwealth Fusion Systems Credit: Prof. Dennis Whyte, MIT 83

Fusion energy is sustained by self-heating and recycled neutrons Neutron lacks charge and Energy Before (MeV) escapes plasma with 80% of the fusion energy

~ 0.01 14.1

~0.01 3.5 3/22/2022 Copyright Commonwealth Fusion Systems Credit: Prof. Dennis Whyte, MIT 84

Fusion energy is sustained by self-heating and recycled neutrons Energy Before (MeV)

~ 0.01 14.1 0.03x10-6 MeV Heat

~0.01 Neutron undergoes collisions with nuclei in Electricity surrounding blanket material like lithium 3/22/2022 Copyright Commonwealth Fusion Systems Credit: Prof. Dennis Whyte, MIT 85

Fusion energy is sustained by self-heating and recycled neutrons Energy Before (MeV) 6-Li + n He + T + 4.8 MeV

~ 0.01

• Thermal neutron interacts

~0.01 with lithium in blanket, creating Tritium and He

• Tritium then fused in plasma

• If Tritium / neutron >1, then fusion only needs deuterium and lithium as fuel inputs 3/22/2022 Copyright Commonwealth Fusion Systems Credit: Prof. Dennis Whyte, MIT 86

Fusion power balance controlled by three parameters:

density of fuel, confinement time and fuel temperature

• Energy confinement time is defined as the ratio of plasma thermal energy density (W) to power density lost by plasma E =

l

• Plasma stored energy set by plasma density (n) and temperature (T)

= 3

• Fusion volumetric reaction rate is dependent on the plasma density and the Q>1 fusion reaction rate R which depends on T 1

= 2()

4

• The power lost by the plasma must be balanced by the fusion power generated in the charged particles to sustain the temperature charge loss

• Combining the above, creates the Lawson Criteria: a minimum of the product of energy confinement time and the plasma density as a function of temperature which for D-T fusion 12 E

charge()

• Sometimes multiplied with temperature to form the triple product 3/22/2022 Copyright Commonwealth Fusion Systems Credit: Prof. Dennis Whyte, MIT 87

Fusion power balance controlled by three parameters:

density of fuel, confinement time and fuel temperature

• Energy confinement time is defined as the ratio of plasma thermal energy density (W) to power density lost by plasma T is very high but n very low E =

l (1/100,000 of air)

• Plasma stored energy set by plasma density (n) an d This energy density temperature (T) is less

= 3 than boiling water

• Fusion volumetric reaction rate is dependent on the plasma density and the Q>1 fusion reaction rate R which depends on T 1 Fusion power controlled by plasma

= () density, which is controlled by puffing gas 2 D-T fusion is easiest 4 fuel to achieve

• The power lost by the plasma must be balanced by the fusion power generated sustainment >x10 in the charged particles to sustain the temperature charge loss Fusion reactions sustained

• Combining the above, creates the Lawson Criteria: by a minimum heating, NOT of the product a chain of reaction energy confinement time and the plasma density a s a function of temperature which for D-T fusion Want to operate near T optimization 12 E Runaway process is physically impossible charge()

• Sometimes multiplied with temperature to form the triple product 3/22/2022 Copyright Commonwealth Fusion Systems Credit: Prof. Dennis Whyte, MIT 88

What is a burning plasma?

• Recall 1/5th of fusion power heats plasma, so Q>5 plasma is dominantly heated by its own product (He ions), this is a burning plasma

• Practical energy systems need Q>10 due to energy conversion efficiencies

• SPARC will be a U.S.-based Q~10 experiment and will be regulated under 10 CFR 30, at least 10 years ahead of ITER

• A burning plasma is not the same thing as critical mass in fission

• All the same safety attributes of fusion (e.g.

defaulting to off in case of loss of power or air leakage in) still apply to burning plasma facilities and higher Q facilities 3/21/2022 Copyright Commonwealth Fusion Systems 89

CFS path to commercial fusion energy COMPLETED COMPLETED COMPLETED CONSTRUCTION Early 2030s Proven science October 2020 September 2021 UNDERWAY Fusion power on the Alcator C-Mod Published peer- Demonstrate Operation in 2025 grid Pelectric~200MW reviewed SPARC groundbreaking Achieve net energy from physics basis in magnets fusion Journal of Plasma Physics HTS Magnets SPARC ARC 3/21/2022 Copyright Commonwealth Fusion Systems 90

Construction progress as of March 2022 3/21/2022 Copyright Commonwealth Fusion Systems 91

Construction progress as of March 2022 3/21/2022 Copyright Commonwealth Fusion Systems 92

Tritium will be delivered and stored in metal beds Certified Type B(U) shipping package, 10 g tritium capacity:

• UK Competent Authority: GB/360D/B(U) DU Storage Bed 3 g T2 capacity (nominal)

• Canadian Nuclear Safety Commission: CDN/E204/-96 (rev 7)

• U.S. Department of Transportation: USA/0596/B(U)-96 rev 6 To Fuel Delivery TM Assay Tank P 4 P TM Spare D2 T2 USB USB USB spare Circulating from Isotope pump Separation Vacuum spare Tritium Storage and Delivery System functions:

• Remove helium-3

• Assay tritium inventory

• Provide safe storage medium Legend:

• Deliver gas to Torus - TM: Tritium Monitor

• Accept gas from isotope separator - USB: (Depleted) Uranium Storage Bed

- P: Pressure Transducer 3/21/2022 Copyright Commonwealth Fusion Systems 93

Tritium gas release can be recovered as elemental gas using an inert atmosphere glovebox Net release to the stack from 1 Ci input:

0.00008 Ci or 80 Ci Photo Credit: University of Rochester - LLE 3/21/2022 Copyright Commonwealth Fusion Systems 94

ARC tritium handling system builds on SPARC Tritium Storage1

• ARCs tritium Fuel Injection Tritium Delivery To stack handling system builds on what is used for SPARC Blanket Tritium Recovery Storage bed2 and is different Torus System from the cryogenic HTO/HT Convertor distillation system that ITER Divertor uses pumps

• Tritium burnup:

80.6 g/day Vacuum Pumps Torus Exhaust Purification Water Treatment3 Isotope Separation1

• Tritium decay:

0.03 g/day SPARC Tritium

• Tritium Handling Systems generation: Added ARC Tritium 88.7 g/day Photo credits:

Handling Systems 1 - University of Rochester - LLE 2 - Torion Plasma Inc Trace Tritium Recovery1 3/21/2022 3 - Nuclear Sources and Services Inc Copyright Commonwealth Fusion Systems 95

SPARC tritium handling systems have significant operational experience Subsystem TRL Operation Experience Experience (years)

Water Treatment System 9 Nuclear Services and Sources, Inc., AECL, KIT, 60 SCK-CEN Isotope Separation 9 Lab for Laser Energetics (LLE), Univ of 7 Rochester, SHINE Medical Inc. (under construction)

Torus Exhaust Purification 6-7 KIT operational experience, Critical component 14 validation at LLE Trace Tritium Recovery 8 LLE (half scale) 18 Tritium Storage and 9 LLE, Ontario Hydro Research Lab, SHINE 50 Delivery Glovebox Cleanup System 9 LLE, Ontario Hydro Research Lab, SHINE 50 Blanket 3 CFS/MIT research and development underway 0 Tritium Recovery System 3 CFS/MIT research and development underway 0 HTO/HT Convertor 4 CFS/MIT research and development underway 0 3/21/2022 Copyright Commonwealth Fusion Systems 96

Fusion can be effectively shielded using existing solutions

• Neutron and prompt gamma shielding with concrete and borated polyethylene

• Activation of components

• Requires gamma shielding

• Not a concern during pulses

• Designs will accommodate for when shielding blocks need to be moved during maintenance 30% borated

• Dose map modeling to ensure sufficient polyethylene shield over time as activation products build-up

• Shielding model for SPARC shows that the Fusion neutron energy dose at the site boundary is below regulatory public dose limits 3/21/2022 Copyright Commonwealth Fusion Systems 97

Fusion waste disposal works with existing regulations

• Four existing low level waste disposal facilities in the US provide sufficient solutions

• Low level radioactive waste disposed of in accordance with existing NRC requirements

• Decay in Storage when applicable can be done (NUREG-1556, Vol. 21, Appendix M)

• Interim storage facilities and equipment for both low-level dry active waste products as well as higher activity tokamak components

• Means to handle components in storage, allow for decay prior to reuse/repair or packaging and disposal, and allow for periodic inspection and detritiation

• Process controls to ensure that the final waste product meets the acceptance criteria of its intended long-term disposal site 3/21/2022 Copyright Commonwealth Fusion Systems 98

Tungsten vacuum vessel wall produces 100x less dust and retains 100x less tritium than a carbon wall

• Source term is dominated by tritium adsorbed on the torus walls with smaller contributions from in-vessel tritium during a pulse and tritium adsorbed on dust particles

• Tungsten wall provides ~100x less dust than carbon wall systems (which most of the published literature is based on), JET produced ~1-2 g from an entire operational campaign with new ITER type wall

• Source: M. Rubel, et al., Dust generation in tokamaks: Overview of beryllium and tungsten dust characterization in JET with the ITER-like wall, Fusion Engineering and Design 136 (2018) 579-586.

• Tungsten dust also retains ~100x less tritium than carbon dust

• Source: T. Otsuka, et al., Tritium retention characteristics in dust particles in JET with ITER-like wall, Nuclear Materials and Energy, 17 (2018) 279-283 3/21/2022 Copyright Commonwealth Fusion Systems 99

Loss of vacuum is the licensing basis event for tokamaks

• Loss of vacuum is likely to be the licensing basis event for a tokamak

• The vacuum vessel is under a vacuum, a hole initiates the event, air rushes in, not out

• This is the opposite of fission systems which contain radionuclides under pressure and are forced out in case of a rupture

• After the torus air balances with the torus hall air, tritium may slowly diffuse out over time, providing ample time to take corrective action

• If the trace tritium recovery system is operational, all released tritium will be collected resulting in negligible emissions to the environment Photo Credit: University of Rochester - LLE 3/21/2022 Copyright Commonwealth Fusion Systems 100

Low off-site doses from a licensing basis event suggests ARC is unlikely to need any active safety grade systems

• For this unreviewed estimation, assume a loss of vacuum event and do not take credit for the trace tritium recovery system

• ARC total inventory at any one time 900,000 Ci (90 grams)

• Assume half of the total tritium inventory (45 grams) is adsorbed in the torus wall

• This amount of tritium on the walls is dictated by operational control and is much more than what would be allowed by internal administrative procedures

• Conservative torus wall release fraction of 30% (13.5 grams)

• Based on the best release fraction JET achieved under optimal venting conditions. Source: P. Andrew, et al., Tritium retention and clean-up in JET, Fusion Engineering and Design, Vol 47, p. 233-245, 1999.

• JET was licensed assuming a 10% release fraction in their design basis. Source: A. Bell, "The Safety Case for JET -T Operation," JET-P, p. P(99)07, 1999.

• Tritium is released in the form of HT, not HTO, and 10% of HT converts to HTO (1.35 grams)

• Source: P. Ebey, Conversion of tritium gas into tritiated water (HTO), LA-UR-01-1825, LANL

• Essentially no radiological significance for HT form of tritium (1/20,000 of HTO dose)

• HOTSPOT assumptions per NUREG-1140: no credit for any active mitigation, building release at 10 meters elevation of building roof, stability class F, wind speed of 1 meter per second

• HOTSPOT results: maximum dose of 370 mrem at 500 meters (location of the maximum dose not necessarily the site boundary) 3/21/2022 Copyright Commonwealth Fusion Systems 101

Summary

• CFSs tritium handling system design is based on decades of successful operating history

• Fusion facilities can be effectively shielded using existing solutions

• LLW disposal can be accomplished with existing NRC regulations

• A very conservative loss of vacuum event for ARC results in doses below the 1000 mrem limit at the site boundary which means:

• No need for any active safety grade systems and

• No need for off-site emergency evacuation response

• CFS believes the current byproduct material regulatory model (10 CFR 30) is sufficient to ensure a safe and cost-effective fusion energy industry 3/21/2022 Copyright Commonwealth Fusion Systems 102

The fastest path to limitless, clean energy 3/21/2022 Copyright Commonwealth Fusion Systems 103 10

Time Topic Speaker 1:00 pm Introductions NRC 1:15 pm Identification and Characterization of Dr. Patrick White Fusion Hazards 2:15 pm Overview of Fusion Industry Association Andrew Holland, Fusion Member Company Commercial Device Industry Association &

Agenda Operational & Off-Normal Safety Case Derek Sutherland, CT Fusion 3:30 pm Break 3:40 pm Overview of Tritium Handling Systems Tyler Ellis, Commonwealth Fusion Systems 4:25 pm Supplemental Discussion of the Helion David Kirtley, Helion Device Safety Case Energy 4:55 pm Question and Answer Period 5:30 pm Adjourn 104

Helion Energy:

Supplemental Safety Case Analysis March 23, 2022 105

Outline

• Device Overview

• Operational Safety

• Accident Analysis 106

Device Overview 107

How Helion Works Magneto-Inertial Fusion

• Two toroidal plasmas (FRCs) are accelerated from opposite ends of the accelerator.

• They collide supersonically and are adiabatically compressed by a magnetic field to fusion conditions.

• Process is 100 microseconds, enables 1-10 Hz pulses.

2 3 Non-Ignition Fusion 1D + 2He 42He + 11H + 18.3 MeV

• Uses D-3He fuel (~95% fusion energy released as 2 1D 4

charged particles, only ~5% in neutrons). 2He

• Energy is recaptured through magnetic fields and 3 2He 1 recycled in capacitor bankenabling deployment at Q<2. 1H 108

Scale & Manufacturability 50 MWe Device - Fusion Vessel

• Device composed entirely of manufactured components

~3 meters

• Shielding also can be constructed diameter separately and shipped to site

• No moving parts except valves

~20 meters long (smaller than 18-wheeler) 109

Characteristics of Helions 50 MW Generator Expected specifications:

Power capacity: 50 MW Capacity Factor: 85%

Tritium in Device: 0.015 mg Neutron Output: 1018 n/s Neutron Energies: 2.45 MeV separate from device 110

Antares Building Everett, WA New headquarters Component fabrication and testing Polaris

• Helion's 7th generation facility Polaris

• Groundbreaking: July 2021 Polaris Accelerator

• Net Electricity Demonstration: 2024 111

Operational Safety 112

Fusion During Operation Fusion Device Accelerator (inc. Cyclotron)

• Neutron and photon radiation

• Neutron and photon radiation

• In-process fuel/accelerated particles and exhaust

• In-process fuel/accelerated particles and exhaust

• Activated shielding

• Activated shielding Key Concept: Fusions operational impacts are fundamentally similar to that of a particle accelerator.

113

Particle Accelerators are Common IAEA Website: https://nucleus.iaea.org/sites/accelerators/Pages/default.aspx Broad federal & state experience regulating such devices 114

Helion Commercial Neutron Shielding Hydrogenous shielding

• Neutron dose attenuated by a passive shielding vault. Borated concrete Roof:

• Only ~5% D-3He fusion output in neutrons (2.45 MeV)

• Hydrogenous shielding

• Lead

• Steel structure

• Shielding similar in size to commercial accelerators (external)

• Regulatory Precedent: Part 36 // §36.25 Shielding (e.g., 2 mrem/hr dose limit following shielding)

Cable feedthroughs:

• Filled with cable, or Shielding thickness anticipated to

• Plugged with hydrogenous be less than two meters. shielding 115

No Post-Shutdown Cooling Required 50 MW Device Metric 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> 1 day 1 week 1 year Driving Device Inventory* 44 kCi/m3 8 kCi/m3 275 Ci/m3 < 1 Ci/m3 Device Latent Heat 40 W/m3 6.5 W/m3 << 1 W/m3 << 1 W/m3 Cumulative Temp. Increase** 7C 18 C 6C 0 C Dose at Machine Surface 4 rem/hr 0.2 rem/hr 4 mrem/hr 0.004 rem/hr

• Driver: activated aluminum (Al-28, 2.3-minute half life)

• • Assume 5 W/m2 convective cooling 1.0E+05 20 18 16 Temperature Increase (C) 1.0E+04 Latent Heating (W/m3) 14 Latent Heating 12 1.0E+03 10 8

6 1.0E+02 4

2 1.0E+01 0 1.E+00 1.E+02 1.E+04 1.E+06 1.E+08 1.E+10 Time (s)

Key Concept:

• Enables a shutdown scenario similar to industrial facilities and particle accelerators.

• Activation products cool rapidly, in comparison to spent nuclear fission fuel. 116

Accident Analysis 117

Subject of Analysis Helion 50MW Facility - Basic Layout Exhaust Piping Fusion device (isolation valves)

(0.015 mg tritium pulse exhaust) (trace levels of tritium) Tritium Storage (separate room/bldg.)

(getterbeds)

Key Concepts:

• Tritium can be separated from the Helion device and addressed as separate materials handling issue.

• Enables analysis to focus on the (fixed & limited) inventory within the fusion device.

118

Simplified Device Release Analysis Analytical Tools

• Simplified Analysis (extreme hypothetical):

o All tritium gas released and converted to HTO (~ 0.015 mg)

• Release Mapping - HotSpot v.3.1.2 o Entire vacuum vessel wall turned to dust

• Dust Activation Rate Analysis - MCNP6.2

• Tritium Release Evaluation:

Silica Dust Profile o 0.015 mg 4.0 rem (max value at 470m)

• Dust Release Evaluation:

o Primary dust concern: 31Si created w/ 2.45 MeV neutrons o Dust equilibrium: 190 Ci in hours (2.6 hr. half life, 1.27 MeV ) ~8 o Vacuum chamber wall 11.3 mrem (max value at 460m) H. Sorek, H.C. Griffin, Fast Neutron Activation Analysis of Silicon in Aluminum Alloys, Journal of Rad. Chemistry, 79, 1, 1983.

• Physically realistic impacts would be much less.

Key Takeaway: Device impacts are fundamentally limited compared to fission systems, and akin to industrial facilities. 119

Fusion Tritium Cycle for Alternative Fuels He-3 fuel recycled

• Tritium is a byproduct, not a fuel

• Tritium gas is not vented 120

Summary From a technical perspective, fusion device impacts are far more akin to a particle accelerator or industrial facility than a fission reactor.

• Impacts profile identical to particle accelerator.

Operational

• Addressed through common shielding practices.

Impacts

• No need for active cooling on shutdown.

• The device is the unique consideration; stored tritium Accident is a standard radioactive materials management issue.

Impacts

• Tritium & dust release concerns are consistent with industrial facilities.

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Questions & Next Steps

• How can we best assist the NRC?

• What additional information would help?

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Limitless clean energy, powered by fusion.

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Time Topic Speaker 1:00 pm Introductions NRC 1:15 pm Identification and Characterization of Dr. Patrick White Fusion Hazards 2:15 pm Overview of Fusion Industry Association Andrew Holland, Fusion Member Company Commercial Device Industry Association &

Agenda Operational & Off-Normal Safety Case Derek Sutherland, CT Fusion 3:30 pm Break 3:40 pm Overview of Tritium Handling Systems Tyler Ellis, Commonwealth Fusion Systems 4:25 pm Supplemental Discussion of the Helion David Kirtley, Helion Device Safety Case Energy 4:55 pm Question and Answer Period 5:30 pm Adjourn 124

Questions and Wrap-up 125

Thank You!

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