Brandon Sorbom, Zach Hartwig, D. Brunner, M. Greenwald, J. Irby, B. LaBombard, Y. Lin, E. Marmar,

R. Mumgaard, A. White, D. Whyte, S. Wukitch

Presented by Brandon Sorbom – Commonwealth Fusion Systems

APS-DPP Portland - November 6, 2018

Nuclear Implications of SPARC

1

SPARC V0 technical objectives:

• Burn D-T fuel

• Q > 2

• Pfusion > 50MW up to 100MW

• Pulsed with 10s flattop burn

(about 2x tCR)

• ~1,000 D-T pulses, >10,000 D-D full-power pulses

• ~1 hr D-T pulse repetition rate

• ~15 minutes between D-D shots

SPARC V0: Nominal Starting Point

Ro 1.65 m

a 0.5 m

e 0.33

k 1.8

B0 12 T

IP 7.5 MA

Bmax 20.9 T

Pfus 50-100 MW

Pext 30 MW

2

Guiding principles for mitigating the risk from SPARC’s Q>2 D-T nuclear mission

1) Recognize from the beginning that the nuclear component of SPARC’s mission touches almost all aspects of the project

2) Design SPARC to achieve its Q>2 demonstration mission while minimizing the nuclear impact as much as possible

3) Ensure that SPARC’s nuclear mission is within D-T tokamak precedence

4) Apply ITER lessons learned to SPARC device design and nuclear safety

5) Rely on gold standard, state-of-the-art computational tools; validate results against experiment whenever possible

3

TFTR [3](‘93-’97)

JET [3](‘91, ‘97)

SPARC(proposed)

T onsite limit [g] 5 90 ~10

T vessel limit [g] 2 20 ~5

T per pulse [g] < 0.05 < 0.25 < 0.1*

Burn length [s] ~3 ~5 10

Total DT pulses [#] ~750 ~135 500 – 3000

Fusion Power [MW] ~10.5 ~16 50 – 100

Neutron rate [n/s] 3.7e18 5.7e18 1.8-3.5e19

SPARC nuclear mission fits within the precedent of previous D-T tokamaks

SPARC’s high-field, compact design enables Q>2 mission and steady-state plasma physics in a ~10 second pulse due to small (~5 s) current relaxation time

As a compact, short pulse, D-T burning tokamak, SPARC fits almost perfectly within the nuclear experience of TFTR (USA) [1] and JET (UK) [2]

Tritium quantity, handling Prompt radiation issues (shielding, dosimetry) Material activation, handling Decommissioning Safety protocol

* Assumes 2% tritium burnup

[1] D.M. Meade, Fus. Eng. Des. 27 (1995) 17

[3] G. Federici and C.H. Skinner, Nuclear Fusion Research (Ch 13), Springer, 2005

[2] The JET team, Fus. Eng. Des. 22 (1993) 77

4

TFTR decommissioning (on time, on budget) provides essentially all the relevant protocols, technology, and experience for SPARC

Nuclear missions are similar enough that decommissioning and disposal (D&D) of TFTR is relevant and comprehensive for SPARC (which is only ~10% TFTR volume)

TFTR D&D is extremely well documented and available Timeline: Oct 1999 – Sept 2002 (finished on-time) Cost: $46M (finished on-budget) Achieved: D&D on 44,658 cubic-ft radwaste (~100 Ci

activation, ~8200 Ci tritium) Waste in shallow-earth burial @ Hanford WA as Class C

waste for $20 / cubic foot (same level as medical waste, accelerator waste, etc)

Containment diamond wire rope cutting technologydemonstrated safe vessel disassembly

Vessel filled with lightweight concrete tolock in radioactive contamination

5

Comparing test cell size and infrastructure with similar tokamaks sets range required for SPARC

Size 40m x 40m footprint 20m tall 20–100 ton crane capacity ~10m tall crane clearance Hot cell space Remote handling space Space for shielding igloo

Walls 1m – 2m thick High density concrete Underground if possible

Foundation Strong concrete foundation Heavy tonnage capable

6

SPARC siting basis can be drawn from TFTR experience and FIRE design; semi-equivalent nuclear missions

TFTR provides real-world demonstration of appropriate nuclear siting for SPARC

FIRE also provides a mature design forSPARC with a slightly more aggressivenuclear mission than TFTR

SPARC V0 TFTR FIRE

Q >2 0.3 10

Pfusion [MW] 50-100 50-100 100-200

Efusion [TJ] 0.5-1 TJ 5 TJ

On-site tritium [g] <20 5 <30

Pexternal [MW] 30 (ICRF) 40 (NBI) 30 (ICRF)

DT shots every [hr] 1-3 ~0.1 3 hrs

Flattop burn [s] 10s 3s 20s

FIRESPARCTFTR

7

SPARC siting basis can be drawn from TFTR experience and FIRE design; semi-equivalent nuclear missions

TFTR provides real-world demonstration of appropriate nuclear siting for SPARC

FIRE also provides a mature design forSPARC with a slightly more aggressivenuclear mission than TFTR

SPARC V0 TFTR FIRE

Q >2 0.3 10

Pfusion [MW] 50-100 50-100 100-200

Efusion [TJ] 0.5-1 TJ 5 TJ

On-site tritium [g] <20 5 <30

Pexternal [MW] 30 (ICRF) 40 (NBI) 30 (ICRF)

DT shots every [hr] 1-3 ~0.1 3 hrs

Flattop burn [s] 10s 3s 20s

FIRESPARCTFTR

Need to be deliberate about siting, but there are many locations which could work. Site

selection is underway.

8

Activation in SPARC is important to quantify and placein context with common scientific, industrial levels

Facilities have 4+ megacuries of cobalt-60 Targets exposed up to 10 megarem doses Cobalt-60 rods routinely exchanged, serviced

Gamma sterilization Particle Accelerators

High energy particle accelerators activate structural components (beamline, collimators, targets, etc)

Contact dose rates can easily exceed 1000’s rem/h for weeks to months after beam shutdown

Barbier’s “Danger Parameter” for protons [1]

9

Activation in SPARC is important to quantify and placein context with common scientific, industrial levels

Facilities have 4+ megacuries of cobalt-60 Targets exposed up to 10 megarem doses Cobalt-60 rods routinely exchanged, serviced

Gamma sterilization Particle Accelerators

High energy particle accelerators activate structural components (beamline, collimators, targets, etc)

Contact dose rates can easily exceed 1000’s rem/h for weeks to months after beam shutdown

Barbier’s “Danger Parameter” for protons [1]

Activation levels in SPARC will be well belowthese scientific and industrial facilities that

routinely and safely handle very active materials

10

Apply ITER lessons learned to SPARC diagnostics, device design and nuclear safety

ITER has developed high-fidelity computational tools that tightly couple nuclear analysis and device engineering – we should leverage this expertise!

ITER Example: Activation of cooling water in complex piping system, C-lite system model

Neutronics and engineering analysis should be tightly integrated from project start; once the design is mature it is often too late to remediate neutronics issues

ITER Example: Recent analysis has shown that TF heating has 50% chance of exceeding 14kW limit [1]

10

ITER C-lite neutronics model

[1] M. Sawan, “Assessment of Critical Neutronics Issue for ITER, USBPO Seminar, October 2015

ITER FW water cooling neutronics model

11

Apply ITER lessons learned to SPARC diagnostics, device design and nuclear safety

ITER has developed high-fidelity computational tools that tightly couple nuclear analysis and device engineering – we should leverage this expertise!

ITER Example: Activation of cooling water in complex piping system, C-lite system model

Neutronics and engineering analysis should be tightly integrated from project start; once the design is mature it is often too late to remediate neutronics issues

ITER Example: Recent analysis has shown that TF heating has 50% chance of exceeding 14kW limit [1]

11

ITER C-lite neutronics model

[1] M. Sawan, “Assessment of Critical Neutronics Issue for ITER, USBPO Seminar, October 2015

ITER FW water cooling neutronics model

We are already starting to think about diagnostic design in the SPARC nuclear

environment. For more details, visit Poster Session UP11 on Thursday

UP11.00070: Diagnostics for a SPARC-like, high-field, compact, net-energy tokamak

12

State-of-the-art neutronics is being developed for SPARC: high-confidence inputs for engineering, safety, licensing

1) DAGMC has been used to allow direct radiation transport on CAD models in MCNP, the industry “gold standard” neutronics modeling code

2) FISPACT-II (EU) and ALARA (US) have been interfaced with DAGMC for activation analysis

3) SPARC plasma profiles have been used to create a high-fidelity neutron source for MCNP models

4) Visualization of geometry and all neutronics results now migrated to Visit, the premiere tool for highperformance computing data used by LLNL

V0 geometry in DAGMC SPARC Neutron Source

TF heating visualization in VisIt

13

State-of-the-art neutronics is being developed for SPARC: high-confidence inputs for engineering, safety, licensing

1) DAGMC has been used to allow direct radiation transport on CAD models in MCNP, the industry “gold standard” neutronics modeling code

2) FISPACT-II (EU) and ALARA (US) have been interfaced with DAGMC for activation analysis

3) SPARC plasma profiles have been used to create a high-fidelity neutron source for MCNP models

4) Visualization of geometry and all neutronics results now migrated to Visit, the premiere tool for highperformance computing data used by LLNL

V0 geometry in DAGMC SPARC Neutron Source

TF heating visualization in VisIt

High-fidelity neutronics is being integrated into the SPARC design from the start.

14

Neutronics shows that the TF HTS magnet is strongly robust to radiation damage for SPARC lifetime

Conservative limits used to assess TF lifetimes:• Insulator (polyamide) limit: 100 MGy [1]• HTS limit: 3x1018 n/cm2 [2]

Location Insulator

@100 Mgy

HTS

@3x1018cm-2

Front ~13,500 ~2,800

Middle ~41,500 ~6,000

Back ~126,700 ~17,400

Number of 10s shots for R=165cm, shield=10cm, B=12T

[1] J.V. Minervini et al., MIT PSFC Report RR-11-10, 2011.

[2] R. Prokopec et al., Fus. Eng. Des. 85 (2010) 227–233

15

Neutronics shows that the TF HTS magnet is strongly robust to radiation damage for SPARC lifetime

Conservative limits used to assess TF lifetimes:• Insulator (polyamide) limit: 100 MGy [1]• HTS limit: 3x1018 n/cm2 [2]

Location Insulator

@100 Mgy

HTS

@3x1018cm-2

Front ~13,500 ~2,800

Middle ~41,500 ~6,000

Back ~126,700 ~17,400

Number of 10s shots for R=165cm, shield=10cm, B=12T

[1] J.V. Minervini et al., MIT PSFC Report RR-11-10, 2011.

[2] R. Prokopec et al., Fus. Eng. Des. 85 (2010) 227–233

SPARC would increase DT operational experience ~10x before burning out due to magnet irradiation

16

Want to help?

MeetingWhen: Today (11/6) at 5PM Where: Room C123, Oregon Convention Center

And/or ContactMartin Greenwald g@psfc.mit.eduBob Mumgaard bob@cfs.energy