Reference Power System Options for the Nuclear...

Reference Power System Options for the Nuclear Power Assessment Study Lee S. Mason NASA Glenn (Presenter) Jeffrey G. Schreiber, Paul C. Schmitz NASA Glenn Jean-Pierre Fleurial, David F. Woerner NASA JPL Dirk Cairns-Gallimore, Anthony Belvin Department of Energy Patrick R. McClure, David I. Poston Los Alamos National Lab Stephen G. Johnson, J. Stephen Herring Idaho National Lab Christopher R. Robinson, John T. Creasy Y12 National Security Complex Martin E. Fraeman Johns Hopkins APL

NETS 2015, Albuquerque NM February 23-27, 2015

Radioisotope Power Systems Program

System Study Team Methodology • Assemble expert team from GRC, JPL, APL, DOE, LANL, INL,

ORNL, and Y12

• Develop new power system options for Planetary Science that could be extensible to HEOMD

– Consider 20-year time horizon, 2016-2036 – Build on MMRTG and ASRG developments – Infuse new technology that improves performance, mass, cost,

robustness, and mission applicability – Identify systems that share common components and technologies

• Develop system concepts that respond to TSSM and UOP

reference missions – Provide systems that deliver higher power for expanded spacecraft

capabilities and mission benefits – Identify RPS that are extensible to Discovery/New Frontier mission

classes – Identify FPS that could be extensible to HEOMD Mars Surface missions

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System Study Team Products • Focus on three technology options

– Advanced Radioisotope Thermoelectric Generator (ARTG) with General Purpose Heat Source (GPHS) Modules

– Stirling Radioisotope Generator (SRG) with GPHS Modules – Kilowatt-class Fission Power System (FPS) assuming Heat Pipe-Cooled, Cast

UMo Core with Highly Enriched Uranium (HEU) • Provide parameterized system performance projections to Mission

Study Team – 8, 12, 16, 18 GPHS ARTG – 2, 4, 6, 8 GPHS SRG – 0.5, 1, 1.5, 3 kWe TE FPS – 1, 3, 5, 10 kWe Stirling FPS – Emphasis on EOM performance (i.e. 3 yr storage + 14 yr mission)

• Supported Mission Study design sessions – Titan Saturn System Mission (TSSM) RPS: 16 GPHS ARTG (3X), 6 GPHS

SRG (3X+1) – TSSM FPS: 1 kWe Stirling, 1 kWe TE – Uranus Orbiter Probe (UOP) RPS: 9 GPHS ARTG (2X), 4 GPHS SRG (2X) – UOP FPS: ~10 kWe Stirling

• Generate system cost estimates for 5 systems: – 16 GPHS ARTG, 6 GPHS SRG, 1 kWe Stirling FPS, 1 kWe TE FPS, 10 kWe

Stirling FPS

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Modular ARTG Concept • Two GPHS Step 2 modules can be stacked up to 16 GPHS modules total

– Mid-span support needed for 12-GPHS and 16-GPHS versions • Enables more flexibility for missions to “right size” their power system (and

minimize costs) • Modular system configuration requires use of TE module assemblies to

achieve 32.6V per 2-GPHS section while maintaining good mechanical robustness

Cantilevered Segmented Module for Modular ARTG

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Common TE Building Block for RPS and FPS

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• Common building block is multi-couple segmented TE module

– Uses ATEC Segmented Couple technology that has demonstrated 15% efficiency

– Basic module “skeleton structure” can be integrated into cantilevered and spring-loaded module configurations

ATEC Segmented Couple

Cantilevered Segmented Module for Modular ARTG

Spring-Loaded Segmented Module for HT-MMRTG and Small FPS

Heat Collector

Radiator Attachment

“Module Bar” with Spring-loaded pistons

“Bare Hot Shoe”

Aerogel filling

Aerogel filling

• Segmented TE Module could be used for both RPS and FPS - 8 couples per module - Cantilevered 8-couple module for use

in Modular and single point design ARTGs - Spring-loaded 8-couple module for use in High

Temperature MMRTG and small FPS For both distributed and compact Small FPS converter

architectures

Basic Building Block:

ATEC Segmented “Skeleton Structure”

“Skeleton structure” includes: • Common “hot shoe” with

compliant metal/ceramic header • Array of segmented TE couples

connected in series/parallel • Cold side interconnects

ARTG

FPS


Common Converter SRG Concept • Address SMD (and possibly HEOMD) mission

needs – Discovery class ~200 We – New Frontiers class ~400 We – Flagship class ~500 to 1000 We

• Minimize Pu238 usage • Apply ASRG lessons learned • Maintain technology heritage with ASC • Emphasize robustness over performance • Incorporate features that extend mission use and

improve fault tolerance (e.g. balancers, spare converters)

• Identify common Stirling converter unit that extends over RPS and fission power ranges

• Identify common design elements that can be shared among RPS and fission systems (e.g. high temperature alternator, modular controller, cold-end heat pipes)

80W ASC 200W ASC-H

SRG-200 (3 GPHS)

SRG-500 (8 GPHS)

SRG-400 (6 GPHS)

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Stirling Generator Concepts ASRG SRG-200 SRG-400 SRG-500 KP-1

BOM Power

140 We 193 We 370 We 495 We 1097 We

No. GPHS 2 3 6 8 Fission

Ht Source Config.

Dist. & dedicated

Centralized & shared using heat pipes

Dist. & dedicated

Distributed & shared using heat pipes

Stirling Config.

2X 80W ASC

2X 200W ASC-H 4X 200W ASC-H 8X 200W ASC-H


Common Tech with

RPS!

NPAS FPS Approach • FPS concept derived from 2010 NASA/DOE Small Fission

Feasibility Study performed for NRC Planetary Science Decadal Survey*

– Requirements included 1 kWe, 15 year full power design life, 28 Vdc bus, 10 year flight system development, scalability from 1 to 10 kWe

– Design approach included cast UMo reactor core, Na heat pipes, BeO reflector, single B4C startup rod, and either:

» Distributed SKD/LaTe/Zintl TE Modules, or » Eight ASRG-derived Stirling Converters

• Additional refinements based on “KiloPower” FPS concept developed for STMD Nuclear Systems Project

– Serves as reference design for technology project that includes nuclear-heated reactor concept demonstration test at at the Device Assembly Facility (DAF) in 2017

– Low development cost for 1 kWe-class system projected based on use of Y12 producible UMo fuel, RPS Stirling technology, and available experimental facilities at DAF and the Nevada National Security Site

* See References: http://sites.nationalacademies.org/SSB/SSB_059331, NASA/TM-2011-217099, NASA/TM-2011-217204

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Reactor Core Options from LANL kpwr1a: 4.3 kWt 28.4 kg U235 0.09% Burnup 8X 3/8” HPs

kpwr1c: 21.7 kWt 37.9 kg U235 0.32% Burnup 18X 0.525” HPs

Cores are configured so that failed HP peak fuel temp is similar to 4.3 kWt core Nominal fuel temps are actually much lower in the higher power cores

kpwr1b: 13 kWt 32.9 kg U235 0.22% Burnup 12X 1/2” HPs

kpwr1d: 43.3 kWt 43.7 kg U235 0.56% Burnup 24X 5/8” HPs

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STMD KiloPower Technology Demo

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Kilowatt Reactor Using Stirling Technology (KRUSTy)

Notional FPS

Concept

Thermal-Vac System Test with depleted uranium (DU) core

(Year 2)

HEU Reactor Critical Experiment at DAF

(Year 3)

Thermal Prototype & Materials Testing

(Year 1)


Generator Fueling Constraints Pu-238 Oxide

1.5 kg/yr (9 Fuel Clads/yr)

FY 2024

FY 2025

FY 2026

FY 2027

FY 2028

FY 2029

FY 2030

FY 2031

FY 2032

ARTG 16 GPHS (64 FC)

9 FC 2 Mod + 1 FC

10 FC = 2 Mod + 2 FC

11 FC = 2 Mod + 3 FC

12 FC = 3 Mod

9 FC 2 Mod + 1 FC

10 FC = 2 Mod + 2 FC

11 FC = 2 Mod + 3 FC

12 FC = 1 Mod

+ 2 Mod

1 ARTG

#1

9 FC 2 Mod + 1 FC

SRG 6 GPHS (24 FC)

9 FC 2 Mod + 1 FC

10 FC = 2 Mod + 2 FC

11 FC = 2 Mod + 3 FC

1 HPSRG

#1

12 FC = 3 Mod

9 FC = 2 Mod + 1 FC

10FC = 1 Mod

+ 1 Mod + 2 FC

1

HPSRG #2

11 FC = 2 Mod + 3 FC

12 FC = 3 Mod

1 HPSRG

#3

9 FC = 2 Mod + 1 FC

Expansion beyond 2 kg/yr is likely to require equipment investment and additional staff

Modifications to target design have been identified that can increase production Expansion to 3-4 kg/yr and beyond would require use of 7930-REDC hot cell Each change has ramifications including: 1) additional tests, 2) cost and schedule

impacts, 3) TRL’s and risks are not uniform between the various ideas proposed

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Impact of Pu238 Production on Mission Power

• What is the EOM DC power output that could be produced from the 1.5 kg/yr PuO2 supply? - Consider four different RPS technology options: MMRTG, eMMRTG, ARTG,

and SRG - Assume NPAS values for conversion efficiency, system degradation rates, and

isotope fuel decay

• After 25 years of new Pu-238 production… - MMRTG technology would yield

300 We total EOM power output - eMMRTG technology would

double the power output to about 600 We

- ARTG technology provides a 4 fold improvement over MMRTG, providing nearly 1200We

- SRG offers the greatest return, with a total EOM power output of ~3000 We

- By the year 2050, NASA could deploy about three 16-GPHS ARTGs or ten 6-GPHS SRGs

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System Cost Elements by Phase System Technology Engineering Flight

16 GPHS ARTG (350W EOM)

• SKD/LaTe/Zintl Tech Devt • Couple Tech Mat • TE Module Dev • System Engr

• Qual Unit • Mgmt & Integ

• Flight Unit • Mgmt & Integ

6 GPHS SRG (300W EOM)

• ASRG Fleet Testing • Conv, Cntl, System Tech Mat

• Engr Model & Qual Units • Mgmt & Integ

• Flight Unit • Mgmt & Integ

1 kWe Stirling FPS

• STMD Kilopower • Conv, Cntl Devt and System

Integ. (leverages SRG) • Phenomenology Identification

and Ranking Table • UMo Fuel PIE • NASA Pre-Phase A Study

• Reactor EM & Qual Units • Balance of Plant EM & Qual

(GRC est.) • Nuclear Safety Testing • EM Non-nuclear System Test

(with DU core) • EM Nuclear System Test (2nd

HW set with HEU core) • EM Reactor Core PIE • Mgmt & Integ

• Flight Reactor • Flight BOP • Rx & BOP Integ. • Reactor Accept. Test • Reactor Shipping • Mgmt & Integ

1 kWe TE FPS • TE Module Devt (leverages ARTG)

• In-core Heat Pipe Integration

• 1.2X Reactor & System Qual Costs

• 1.2X Reactor & System Accept. Costs

10 kWe Stirling FPS

• Conv, Cntl Devt and System Integ. (leverages P2A)

• In-core Heat Pipe Integration

• 1.5X Reactor & System Qual Costs

• 1.5X Reactor & System Accept. Costs

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ROM System Costs by Phase

$223M $239M $425M $456M $712M

Assumes use of converters already developed as part of

the ARTG (TE) and SRG (Stirling) efforts

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Summary • Current MMRTGs and planned Pu-238 production levels

fulfill a subset of SMD mission needs, but with little margin – Pu-238 is a precious resource and needs efficient utilization and preservation

• Additional programmatic flexibility achieved through maturation of high efficiency advanced TE and Stirling conversion technologies

– ARTG approach offers modular block for systems from 40 We (2 GPHS) to 450 We (18 GPHS)

– SRG approach offers common convertor option for systems from 200 We (3 GPHS) to 500 We (8 GPHS)

– Key is to develop robust technologies with high efficiency and low degradation to achieve high EOM power output

• SMD has no current requirements for a mission power system at the 1 kWe level or higher, and so no current requirement for an FPS exists

– FPS are likely to be needed for human mission to Mars – STMD Kilopower project intends to demonstrate technology feasibility for

kilowatt-class FPS – Use of RPS conversion technologies provides promising path for future flight

implementation

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