Design of megawatt power level heat pipe reactors

TLDR: In this article, the authors developed a scalable conceptual design for a compact fast-spectrum nuclear reactor and identified scaling issues for compact heat pipe cooled reactors in general, and developed two detailed concepts, the first concept with more conventional materials and a power of about 2 MWe and a the second concept with less conventional materials with a power level of about 5 MWe.

Abstract: An important niche for nuclear energy is the need for power at remote locations removed from a reliable electrical grid. Nuclear energy has potential applications at strategic defense locations, theaters of battle, remote communities, and emergency locations. With proper safeguards, a 1 to 10-MWe (megawatt electric) mobile reactor system could provide robust, self-contained, and long-term power in any environment. Heat pipe-cooled fast-spectrum nuclear reactors have been identified as a candidate for these applications. Heat pipe reactors, using alkali metal heat pipes, are perfectly suited for mobile applications because their nature is inherently simpler, smaller, and more reliable than “traditional” reactors. The goal of this project was to develop a scalable conceptual design for a compact reactor and to identify scaling issues for compact heat pipe cooled reactors in general. Toward this goal two detailed concepts were developed, the first concept with more conventional materials and a power of about 2 MWe and a the second concept with less conventional materials and a power level of about 5 MWe. A series of more qualitative advanced designs were developed (with less detail) that show power levels can be pushed to approximately 30 MWe.

Figures

Figure 16. Time and core average axial power distribution.

Figure 17 Peak power pin location temperatures.

Figure 1 Sizes Range of Reactor Applications

Table 1 SS_UO2 and Moly_UN Concept Performance

Figure 23 Mobile heat pipe reactor in shipping cask

Figure 13 Core radiation transport schematic, Core (blue), reflector (orange), green is core block, blue is fuel, white circles are heat pipes, orange is alumina, yellow is boron carbide.

Full text

LA-UR-15-28840
Approved for public release; distribution is unlimited.
Title: DESIGN OF MEGAWATT POWER LEVEL HEAT PIPE REACTORS
Author(s): Mcclure, Patrick Ray
Poston, David Irvin
Dasari, Venkateswara Rao
Reid, Robert Stowers
Intended for: Report
Issued: 2015-11-12

Disclaimer:
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viewpoint of a publication or guarantee its technical correctness.

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DESIGN OF MEGAWATT POWER LEVEL HEAT PIPE REACTORS
Patrick McClure, David Poston, D.V. Rao and Robert Reid
Los Alamos National Laboratory
November 2015

ABSTRACT'................................................................................................................................................'3!
INTRO D U C TIO N '......................................................................................................................................'3!
POTENTIAL'ADVANTAGES'..................................................................................................................'7!
SIZE!..............................................................................................................................................................................!8!
ORIENTATION!............................................................................................................................................................!9!
SAFETY!........................................................................................................................................................................!9!
SELF!REGULATION!(LOAD!FOLLOWING)!...........................................................................................................!10!
SOLID!STATE!............................................................................................................................................................!10!
HEAT!TRANSFER!SURFACE!AREA!MOVED!OUTSIDE!CORE!.............................................................................!10!
MORE!CHOICE!OF!FLUIDS!AND!CONFIGURATIONS!...........................................................................................!11!
HIGH!TEMPERATURES!...........................................................................................................................................!11!
SUMMARY!OF!ADVANTAGES!................................................................................................................................. !11!
ISSUES'O N 'SC A L IN G'............................................................................................................................'12!
LIMITAT ION S !ON!SCALING!....................................................................................................................................!12!
LIMITS!ON !NUMBER!OF!HEAT!PIPES!..................................................................................................................!12!
LIMITS!BASED!ON!ACCIDENT!CONDITIONS!.......................................................................................................!12!
LIMITS!ON !HEAT-PIPE !PERFORMANCE!..............................................................................................................!13!
LIMITS!ON !THERMAL!AND!MECHANICAL!PERFORMANCE!..............................................................................!14!
OTHER!MATERIAL!LIMITATIONS!.........................................................................................................................!15!
OVERCOMING'LIMITS'ON'SCALING'...............................................................................................'16!
CORE!SEGMENTATION!...........................................................................................................................................!16!
HEAT!PIPE !PERFORMANCE!–!THE!USE!OF!A!DOUBLE-ENDED!HEAT!PIPE!.................................................!17!
OVERCOMING!THERMAL/MECHANICAL/NEUTRONIC!ISSUES!FOR!NORMAL!AND!ACCIDENT!CONDITIONS
!...................................................................................................................................................................................!18!
DETAILED'ANALYSIS'OF'BLOCK'DESIGNS'(SS_UO2'AND'MOLY_UN)'..................................'19!
QUALITATIVE'TRADE'OFFS'OF'ALTERNATIVE'DESIGNS'.......................................................'28!
RESULTS!OF!ALTERNATIVES!STUDY!...................................................................................................................!35!
FUEL!MATERIAL!.....................................................................................................................................................!35!
BLOCK!MATERIAL!..................................................................................................................................................!35!
RANKING!OF!ALTERNATIVES!................................................................................................................................!36!
OVERALL'LESSONS'LEARNED'AND'RECOMMENDATION'GOING'FORWARD'...................'36!
POSSIBLE!REACTOR!CONCEPT!FOR!REMOTE!LOCATIONS!...............................................................................!36!
APPENDIX'A'..........................................................................................................................................'39!
METHODOLOGY!FOR!ANALYSIS!............................................................................................................................!39!
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DESIGN OF MEGAWATT POWER LEVEL HEAT PIPE REACTORS
Patrick McClure, David Poston, D.V. Rao and Robert Reid
Los Alamos National Laboratory
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Abstract(
An#important#niche#for#nuclear#energy#is#the#need#for#power#at#remote#locations#
removed#from#a#reliable#electrical#grid.##Nuclear#energy#has#potential#applications#at#
strategic#defense#locations,#theaters#of#battle,#remote#communities,#and#emergency#
locations.##With#proper#safeguards,#a#1#to#10-MWe#(megawatt#electric)#mobile#reactor#
system#could#provide#robust,#self-contained,#and#long-term#power#in#any#environment.##
Heat#pipe-cooled#fast-spectrum#nuclear#reactors#have#been#identified#as#a#candidate#
for#these#applications.#Heat#pipe#reactors,#using#alkali#metal#heat#pipes,#are#perfectly#
suited#for#mobile#applications#because#their#nature#is#inherently#simpler,#smaller,#and#
more#reliable#than#“traditional”#reactors.##
The#goal#of#this#project#was#to#develop#a#scalable#conceptual#design#for#a#compact#
reactor#and#to#identify#scaling#issues#for#compact#heat#pipe#cooled#reactors#in#general.####
Toward#this#goal#two#detailed#concepts#were#developed,#the#first#concept#with#more#
conventional#materials#and#a#power#of#about#2#MWe#and#a#the#second#concept#with#
less#conventional#materials#and#a#power#level#of#about#5#MWe.##A#series#of#more#
qualitative#advanced#designs#were#developed#(with#less#detail)#that#show#power#levels#
can#be#pushed#to#approximately#30#MWe.#
Introduc tio n(
Reactors!come!in!a!range!of!sizes.!!The!size!fits!a!variety!of!applications!as!shown!in!
Figure!1.!!Los!Alamos!National!Laboratory!(LANL)!has!traditionally!designed!
reactors!for!applications!in!the!1!to!200!kilowatt!electric!(kWe)!range!as!shown!in!
first!two!columns!in!Figure!1.!!Most!of!LANL’s!designs!have!been!for!space!
applications!for!the!National!Aeronautics!and!Space!Administration!(NASA.)!!Almost!
all!of!these!reactor!designs!are!based!on!a!small!highly!reflected!fast!reactor!concept!
that!use!heat!pipes!as!the!means!of!heat!removal!from!the!reactor!core.!!This!is!an!
ideal!technology!for!space!where!reliability!and!simplicity!are!key!requirements.!!!
LANL!performed!a!study!to!examine!the!issues!of!scaling!heat!pipe!reactor!
technology!to!the!low!megawatt!electric!(MWe)!range!(shown!in!third!column!of!
Figure!1.)!!The!low!MWe!range!is!an!area!that!was!examined!in!the!1950s!through!
1970s!by!the!U.S.!Army!for!power!at!remote!locations!such!as!the!Arctic,!Antarctica!
and!the!Panama!Canal.!!Power!at!remote!locations!removed!from!a!reliable!electrical!
grid!is!a!potential!future!niche!for!nuclear!energy.!!!Remote!locations!include!
strategic!defense!locations!(such!pacific!island!bases),!theaters!of!battle,!remote!

Frequently asked questions

Q1. What contributions have the authors mentioned in the paper "Design of megawatt power level heat pipe reactors" ?

McClure et al. this paper presented a study to examine the issues of scaling heat pipe reactor technology to the low megawatt electric ( MWe ) range ( shown in third column of Figure 1 ).