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Development Status of the Fission Surface Power Technology Demonstration Unit

Maxwell Briggs, Marc Gibson, and Steven Geng NASA Glenn Research Center

National Aeronautics and Space Administration

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Presentation Outline

• Fission Power Systems • The Fission Surface Power Technology

Demonstration Unit – Overview – Component Development

• Reactor Simulator • Annular Linear Induction Pump • Stirling Engine • Heat Rejection

– Sub-System Testing • Heat Rejection System • RXSim Sub-system

– System Level Test Status

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Fission Power Systems (FPS) Fission Surface Power (FSP) (10 – 100 kW)

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Small Reactor (Kilopower) (1 – 10 kW) Nuclear Propulsion (100 kW - ~1MW)

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FSP Technology Demonstration Unit

• Non-nuclear demonstration of a Fission Surface Power System • Full-scale FSP components • Thermal vacuum environment • Heat provided by a reactor simulator • Originally designed to achieve TRL 6

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Technology Demonstration Unit (TDU)

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∆P +28 kPaat 1.75 kg/s

(0.5-2.5 kg/s)

NaK850 K

∆P +190 kPaat 0.375 kg/s(0.2-0.6 kg/s)

440 kPa160 kPa

H2O~375 K

(925 K and275 kPa max)

(450 K and690 kPa max)

Core Sim48 kWe nom

(90 kWe max)

Waste Heat Exchanger

Pwr Conv12 kWe nom

(14.4 kWe max)

PVA RVA

PP RP

∆P

≤14

kPa

∆P

≤7 k

Pa

∆P

≤15

kPa

Vacuum≤1x10-5 torr

PCU Cntl12 kWe nom

6-13.2 kWe reg.

ELS≥10 kWe

400 Vac

η ≥25%η ≥10%

η ≥90%

120+/-6 Vdc

Waste heat rejected to ambient air

Original Design

Reduced budget design

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Core Simulator

• Core Simulator – Thermally and hydraulically similar to

FSP core – Tested with TDU ALIP at MSFC June

2012 – Delivered to GRC January 2013 – Can be operated in constant power,

constant temperature, or reactivity feedback modes.

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Core simulator

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ALIP

• Annular Linear Induction Pump (ALIP) – Electromagnetic pump / No moving parts – Two Pumps manufactured – Both were tested in the ALIP Test Circuit at MSFC

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ALIP installed at MSFC

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Sub-System Testing at MSFC

• Core simulator demonstrated to 50 kWt

• FSP and TDU ALIP pump curves have been generated • Flow resistance curves have been generated

– Showed that larger of the two ALIPs must be used during TDU testing

• All components tested at nominal and maximum temperatures

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Stirling Power Conversion Units • Two 6 kW Stirling convertors have been fabricated and tested by Sunpower

– Convertor 1 was fabricated in Fall of 2011 – Convertor 2 was fabricated in Spring of 2012

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• Tested as individual convertors - Convertor 1 reached full power in Dec 2011 - Convertor 2 reached full power in July 2012

• Combined into a 12 kW PCU April 2013 • Electrically heated test finished in Late 2014. • NaK heat exchanger fabrication delayed

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Radiator Testing

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Material Innovation 2nd Gen RDU (2009)

GRC Affordable Radiator (2013-2014)

Advanced Cooling Technologies Composite Radiator (2011)

Phase II SBIR with ACT to deliver 6 radiator panels using affordable design approach

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Heat Rejection Sub-System Testing

• Completed in January 2013 – Demonstrated water pump

compatibility in thermal vacuum – Verified start-up, shutdown, and

emergency drain procedures – Pump performance data has

been incorporated into TDU system models

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RxSim Subsystem Test Hot NaK Preparation / Preliminary Work

• NaK Storage • Fill/Drain • Steam Cleaning • NaK and Caustic Disposal • Safety Permit • Operating Procedures

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RxSim Subsystem Test NaK Testing

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• Operated through full operating range • Verified component performance • Validated subsystem models

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TDU System Model Validation

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300

400

500

600

700

800

900

0 1000 2000 3000 4000 5000 6000 7000 8000 9000

Tem

pera

ture

(K)

Time (s)

Model Core NaK Temp

Model ALIP NaK Temp

ALIP NaK Temperature

Core NaK Temperature

0

500

1000

1500

2000

2500

0

500

1000

1500

2000

2500

3000

3500

0 1000 2000 3000 4000 5000 6000 7000 8000 9000

Mas

s flo

w (g

/s)

Pow

er (W

)

Time (s)

ALIP-POW (W)

Model ALIP Power

EM Flow

Model Mass Flow

650670690710730750770790810830

0 1000 2000 3000 4000 5000

Tem

pera

ture

(K)

Time (s)

Cool Down

ALIP Inlet

ALIP OUTLET

ALIP OUTLET

ALIP Inlet

Core Outlet

Core Inlet

Core NaK Temp

Model ALIP NaK Temp

Model Core NaK Temp

• Verify internal Core Sim Temps • Verify Flow and Pump Power • Verify Thermal Losses • Verify Steady-State Operating

Conditions and Transient Response.

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System Level TDU Test Status Fabrication/Assembly Delay

• Complicated braze geometry was difficult to fabricate • New NaK Heater Head Design Being Fabricated

– Material changes eliminated difficult brazes – Final engine assembly scheduled for May 2015

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Conclusion

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Component Testing Complete

Sub-System Testing Complete

TDU Testing scheduled for June 2015