This viewgraph presentation reviews the development of a simulator for non-nuclear tests for the development of a space nuclear power system. The development of the Instrumented Thermal Simulator is to assist in developing an understanding of individual components and integrated  system operation without the cost, time, safety concerns associated  with nuclear testing.  The presentation shows the design, the electrical integration, the hardware, and the assembly of the simulators.  There are slides that show the test plan, the analysis, and the initial results

Bragg-Sitton, Shannon

Dickens, Ricky

Dixon, David

NASA Technical Reports Server

Natlonal AeronautIcS and
Space Adfl"irvstration George C. Marshall Space Fight Center
Development of High Fidelity,
Fuel-Like Thermal Simulators for
Non-Nuclear Testing
Shannon Bragg-Sitton, Ricky Dickens
NASA/MarshaJI Space Flight Center
Nuclear Systems Branch, ER24
Early Flight Fission - Test Facility (EFF-TF)
David Dixon
North Carolina State University
Shannon.M.Bragg-Sitton@nasa.gov
SNC 2007, June 24-28, 2006
https://ntrs.nasa.gov/search.jsp?R=20070032726 2019-08-30T01:42:38+00:00Z
National Aeronautics and
Space Adrrinistralion
Presentation Summary
George C. Marshall Space Fight Center
• Instrumented Thermal Simulator Development
- Design Basis
- Assembly
- Test Configurations
• Results
- Thermal Analysis
- Experimental Results
• Conclusions
• Future Directions
SNC 2007, June 24-28, 2006
National Aeronautics and
Space Administration
Testing Strategy
George C. Marshall Space Fight Center
• Non-nuclear tests can enable the development of a
space nuclear power system ~
Develop an understanding of individual components and
integrated system operation without the cost, time, safety
concerns associated with nuclear testing
• Accomplish through use of specialized electric
heaters to simulate heat from nuclear fuel
- Attempt to match overall fuel properties
- Operation in extreme environments (e.g. vacuum)
SNC 2007, June 24-28,2006
Nattonal Aercnautics and
Space Admnistratlon
Basic Graphite Heater Element Design
George C. Marshall Space Fight Center
Alumina Insulator Rlngsx3
(Cemented to Graphite)
Molybdenum Power Leads
(Cemented Into Graphite)
Graphite Heater Element (Split Rod) Alumina Insulator Shims xl(cemented to Graphite)
0.375" on x 21.6"
• Low cost ("'$200/element)
• Robust "workhorse" heater element
- Withstand instantaneous power changes
- Have been operated for 1OOOs of hours and 100s of thermal cycles
• Can be shaped to provide a prescribed axial power profile
S C 2007, June 24-28, 2006
National Aeronautics and
Space AdrrinlslratJon
Electrical Integration
George C. Marshall Space Fight Center
• Must take into account the total number of heater elements in
small footprint
-7 Complexity significantly increases as the pin size is
reduced and the total number ofpins increases
• Depends on reactor type and operating environment
- Presence of a pressure vessel
- Simulator impact on coolant flow plenum
- Presence of an electrically conductive media in flow plenum
- Requirement of gas inside simulator assembly for improved thermal
coupling
SNC 2007, June 24-28, 2006
57 Simulators,
SAFE 100a
(- 7" by 6.5")
37 Simulators,
Direct Drive Gas
(- 6.25" by 7.1 ")
183 Simulators,
SAFE 100
(-10.4" by 11.5"
48 Simulators,
SAFE 30
(- 9" by 8")
Electrical Integration - Core Face Seal
George C. Marshall Space Fight Center
• Prevents contact with conductive media in liquid metal system
• Allows for operation with high purity gas on ID of simulator
sheath
• Prevents material incompatibility issues
LMCore
Power
Feedthroughs
SNC 2007, June 24-28, 2006
National Aeronautics and
Space Administration
High Fidelity Simulator Design Strategy
George C. Marshall Space Fight Center
• Receive nuclear fuel pin performance characteristics from
reactor designers (steady state and dynamic)
• Develop conceptual design to match pin performance under
nominal steady state operation and during transient maneuvers
• Develop simulator engineering design
• Develop calorimeter test article design (for test w/active heat
removal)
• Build, test, validate - testing ofbare element and with active
heat removal in a relevant environment
• Iterate design to improve performance; demonstrate
repeatability
S C 2007, June 24-28, 2006
Current Simulator Design Objectives
George C. Marshall Space Fight Center
: ------------------- J (J--------------------------------:, [, '~G>,;::;:1;;:;;!.2rbe4:m~~~
2.36em .1+!-------~( ;i - :_~~~~~::~~ Jl.73em
---------- -~. \------ ------ ---- !t.,o' I I I
45.30 em 280 em 207 em
t--- 2.08 cm--I
• Fully instrumented sheath, ill/OD
(TCs, with option for fiber optics
onID)
• Ability to swap out heater element
to test variable axial power profiles
• Minimum impact on flow plenum
(CFD analysis pending)
• Match fuel pin thermal inertia and
clad surface temperature during
steady state and transient operation
• Current simulator corresponds to a
NaK cooled reactor core design
Solid Insulator
Opening for
Heater Element/
Groove for
TC Placement
0.899cm
,+<:::..----j'->. --Jl
SNC 2007, June 24-28, 2006
National Aeronautics and
Space Adrrinlstration
Transient Thermal Analysis: Shutdown
George C. Marshall Space Fight Center
powder
or slurry
AJ,O,
Fuel Element
'0
".
"Solid" Simulator
• • •
.. OJ
.~
He
55316
sheath
7060
--Solid. Qc
-Solid
-Fuel Clad
-Powder
....... Powder, Qc
5030 40
Time (5)
Comparison is made at the axial
midpoint during a shutdown transient.
modeling the simulator with both
constant Qc and a shaped Q. as
derived from the fuel pin analysis.
2010
Shutdown from: 98 kWt, 0.86 kW/pin (nominal)
850
875
870
880 I-------~=:;::;;::_:;_::::;;::;_:;=::::;::__;;_;::;::;::____;:::========:;lSimulator 1: solid + powder AI203
Simulator 2: solid Ab03
- 865e
~
~ 860
.,
Q.
~ 855I-
SNC 2007, June 24-28, 2006 "Powder" Simulator
National Aeronautics and
Space Admnistrabon
Instrunaented Sinaulator: lIardvvare
George C. Marshall Space Fight Center
S C 2007, June 24-28, 2006
National Aeronautics and
Space AdtTinislration
Instrunnented Sinnulator: lIardvvare
George C. Marshall Space Fight Center
SNC 2007, June 24-28, 2006
National Aeronautics and
Space AdrrinlstraUon
Instrunaented Sinaulator: IIardvvare
George C. Marshall Space Fight Center
SNC 2007, June 24-28,2006
Instrumented Simulator: Assembly
George C. Marshall Space Fight Center
SNC 2007, June 24-28, 2006
TCs running along
sheath 10 with bottle
shaped insulator installed
(flashlight used to
illuminate assembly)
TCs installed on bottle
shaped insulator
Te installation on
bottle shaped insulator
Insertion of insulator
into sheath assembly
NalJOnal Aeronautics and
Space Adninistralion
SNC 2007, June 24-28, 2006
National Aeronautics and
Space Adrrinistration
Instrumented Simulator: Test Plan
George C. Marshall Space Fight Center
• Bare Element Checkout Testing
- Verification of basic operation in simplified configuration without added variables
- Vacuum and inert environment (He or Ar)
• Calorimeter Testing
- Active heat removal via water cooled "calorimeter" jacket
- Provides enhanced, tailored, and measured heat extraction at realistic simulator
sheath design temperatures
- Allows measurement of simulator temperature profile and thermal response via TCs
and optical techniques without liquid metal concerns
• Single Flow Cell- NaK Heat Removal
- Representative flow cell from full reactor design
- Characterization of performance in intended operational environment prior to full
core build and test
- Benchmarking of thermal models used for high fidelity (performance matching)
simulator design
SNC 2007, June 24-28,2006
National Aeronautics and
Space AdlJlnlstratiOo
Simulator Instrumentation
George C. Marshall Space Fight Center
SNC 2007, June 24-28, 2006
:e Fight Center
w of assembled simulator
o installation of endplugNational Aen:inautics and
Space AdtJinistratlon
SNC 2007, June 24-28, 2006
National Aeronautics and
Space Adrrinlstration
Thermal Analysis
George C. Marshall Space Fight Center
• Model: Thermal Desktop
• Analysis: Sinda / Fluint
• Models conduction, radiation and natural convection
• Incorporates end effects including:
- Bottle shaped sheath
- Power leads
- End cap
- Axial variation in sheath emissivity
SNC 2007, June 24-28,2006
George C. Marshall Space Fight Center
Test and Analysis Results, Bare Element
National Aeronautics and
Space Adml"llstratiOn
700 ,----- ----""'S-""te""'a......d'-'-"~~
600
500
-o
-e 400
::;,
~
41
~ 300
41
...
200
100
! ++++++++!++++++++++++++~++++++++ !+++ ++++++++ ! +++v":.;--------------! ---------------------------- _1- -~25W
6/- ~
f xxxxxxxxxxxxxxxxxxx~xxxxxxxxxx - 500 W
- XXXXXX ~ ~ xXx><.>c
xxx ~x~xI
~ 250W
"Curves represent model predictions at sheath 00;
data points w/error bars correspond to measured data"-
Emissivity:
SS sheath. center section (assume linear wltemperature):
T =0 K. 0.183
T =1000 K, 0.551
SS sheath, ends (oxidized): 0.85
O+---.----,-----.------.-------.-----.-----.----,-----,------i
o 0.05 0.1 0.15 0.2 0.25 0.3
Axial Position (m)
SNC 2007, June 24-28, 2006
0.35 0.4 0.45 0.5
National AeIonaullcs and
Space Adrrinlstratlon
Transient Results, Bare Element
George C. Marshall Space Fight Center
+25% Power Transient
Data __
-
.J!11""'. S/F, mid-sheath~
~ Data
-V Data S/F, non-power endS/F, bottle neck end
_V
--------- TC 9 (16.5em)
---.. -- TC 10 (26.7em)
--SindalFluint (16.gem)
- - SindalFluint (27.gem)
---.--- TC 7 (1.9 em)
- --<>.- TC 12 (41.1 em)
-- SindalFluint (1.9 em)
--Sinda/Fluint (41.1 em)
, , , ,300
0:00:00 0:07:12 0:14:24 0:21 :36 0:28:48 0:36:00 0:43:12 0:50:24 0:57:36
Time Into Transient
SNC 2007, June 24-28, 2006
400
350
650
600
550
-o
-- 500~
=~
Q>
c. 450E
~
National Aeronautics and
Space Adrnnisltatlon
Transient Results, Bare Element
George C. Marshall Space Fight Center
650 -20% Power Transient
S/F, non-power end
0:43:12 0:50:24 0:57:360:36:00
Data
0:21 :36 0:28:48
Data
S/F, mid-sheath
Data
S/F, bottle neck end
550
350
------ TC 9 (16.5em)
....... TC 10 (26.7em)
-- Sinda/Fluint (16.6em)
- - Sinda/Fluint (26.gem)
--·8--· TC 7 (1.9 em)
---<r- TC 12 (41.1 em)
- Sinda/Fluint (1.9 em)
--Sinda/Fluint (41.1 em)300 +-__----,-__-----,,---__--.--__-----. ,---_...L----.--__----.-_-'-----_,----'--"
0:00:00 0:07:12 0:14:24
600
400
--U
-41 500
...
:::l
E
41
Co 450E
41
I-
Time Into Transient
SNC 2007, June 24-28, 2006
National Aeronautics and
Space AdrrinlsltaUon
Calorimeter Testing
George C. Marshall Space Fight Center
\
I~.",...~\ \
I I
I~....;:;.r\ I
I \I 1\
\ \ \ \I \ \ \-----:;;r- RETURN LINES
I
,
,
\\\, ,
\\
\, II,I I
SK08112006-\ - SPACER
TYP 3 PLACES
I ,
" " " "
'\ '\ '~ I
\ , ,
\
, ,
\ \\ ,\\\ \\\ , ,\ \\ \\ \'\\ ,\\ ,
---- ---
- -
--
-' ---
I ,
II
ALIeN AND LOCATE ALL THREE
VIEWING PORTS ALONG CENTER
SK08102006-1 - CALORIHETER
SK10052006-1 - SUPPORT {ISOLATOR
SOURCE LINES TO BE PROVIDED BY CUSTOMER
SK03012006-1 - BOTTLE SHAPE SHEATH ASSY
SNC 2007, June 24-28, 2006
National Aeronautics and
Space Administration
Installed Calorimeter Hardware
George C. Marshall Space Fight Center
SNC 2007, June 24-28, 2006
Nabonal Aeronautics and
Space Admnistratlon
Initial Calorimeter Results
George C. Marshall Space Fight Center
: ~
• ~.
• .----..
50
o
o
•
5
•
10 15
•
20 25
•
30 35
•
40
•
45 50
Axial Position (em)
SNC 2007, June 24-28,2006
NaK Flow Cell
,83. 4
'71.6
SNC 2007, J
Preliminary flow
cell design
and analysis results.
National Aeronautics and
Space Adrrinisttalion
Thermal Coupling Material Testing
George C. Marshall Space Fight Center
~Solid
-Powder
875
• Materials tested to eliminate second gas gap in simulator design
• Analysis shows that proposed design improves transient performance of
simulator
• Properties ofpowder and slurry materials highly dependent on
composition, packing fraction
• Use in simulator design and fabrication requires repeatability of fill
technique 880 r-------~:;:;::-;-:-::::;;:;-:::-:::::::;::_;::;~____;:::===::::;l
Simulator 1: solid + powder AJ,03
Simulator 2: solid AbO,
55316
sheat~
powder
or slurry
870
- 865~
~
~ 860
..
Co
t 855to-
850
845
Comparison is made at the axial
midpoint during a shutdown transient
modeling the simulator with both
constant Qc and a shaped Q. as
derived from the fuel pin analysis.
-Fuel Clad
...... Powder. Qc
--Solid, Qc
70605030 40
Time (s)
2010
840 l--.-------r------.---~~~---J
o
National Aeronautics alld
Space Administration
Thermal Coupling Material Testing
George C. Marshall Space Fight Center
•
•
•
Ga,ke
Fill gap sized to correspond to simulator design
TCs installed in grooves on vessel ID and OD
Use of a short, high resistance heater to indirectly heat the fill material
Cap
Container for
Thermal Coupling
Material
SNC 2007, June 24-28, 2006
National AerMautic:s and
Space Adrnnistration
Initial Results - Vacuum Testing
George C Marshall Space Fight Center
Average Gap Packing Calculated Fraction ofMaterial Temperature Conductivity Solid (theor.)Fraction(K) (vacuum) Conductivity
Empty Vessel 670K
N/A
0.355 + 0.029 N/A
795K 0.347 + 0.023
Alumina, 4N,
684K 0.28 0.177 + 0.011 0.025
-325 Mesh
Aluminum Nitride, 663 K 0.41 0.640 + 0.071 0.0132N, -325 Mesh
Aluminum Nitride, 671 K 0.209 + 0.014 0.004
3N5, -200 Mesh 730K 0.33 0.271 + 0.017 0.006
Natural Diamond 610K 0.53 0.211 + 0.014 lE-04722K 0.233 + 0.015 lE-04
Carbonaceous 666K 0.906 + 0.131 0.20
Cement, C-34 798K 0.94 0.770 + 0.074 0.18
870K 0.798 + 0.067 0.19
National AeronautICS and
Space Adrnnlstration
Initial Results - Helium Testing
George C Marshall Space Fight Center
Average Gap Packing Calculated Fraction ofMaterial Temperature Conductivity TheoreticalFraction(K) (600 torr He) Conductivity
Empty Vessel 435 K
N/A
0.601 + 0.050 N/A
538 K 0.696 + 0.048
Alumina, 4N, 437K 0.28 1.091 + 0.110 0.156
-325 Mesh
Aluminum Nitride, 432K 0.41 1.138 + 0.140 0.0242N, -325 Mesh 537K 1.213 + 0.208 0.025
Aluminum Nitride, 426K 0.779 + 0.074 0.016
3N5, -200 Mesh 528 K 0.33 0.792 + 0.056 0.017
Natural Diamond 427K 0.53 1.166 + 0.163 5.8E-03530K 1.144 + 0.099 5.7E-03
Carbonaceous 433 K 1.543 + 0.242 0.32
Cement, C-34 535 K 0.94 1.661 + 0.164 0.36
605K 1.852 + 0.165 0.41
Potential Heat Paths
National Aeronautics and
Space AdmnJstraUon George C. Marshall Space Fight Center
• Conductivity results affected by
additional heat transfer along walls and
through ends of test vessel
• Potential Solutions:
Isolate halves of test vessel with non-
conductive end caps
Lengthen test vessel such that minimum
resistance path is across fill gap
Cap
TC Location
Test Vessel
SNC 2007, June 24-28, 2006
Possible Heat Paths
from Heater Element,
as identified by red arrows
CT Analysis: C-34
George C. Marshall Space Fight Center
• Non-destructive analysis to assess fill
density
• High resolution images: 0.1092 mm pixel
SIze
• Results indicate non-uniform C-34 density,
possibly resulting from:
- Heterogeneous composition
- Air bubbles entrained during mixing process
• Achieved 94% theoretical density-
suggests a slurry material provides more
reliable fill than powder fill materials
, • ~1IlIl''' - • ..-. r- -. -= -,.~~-,._ -:--=-~
. .~ ,
" ....
~
- --' -~ ~-- - ~.._~~-~~ --
SNC 2007, June 24-28, 2006
National Aeronautics and
Space AdlTinlstration
Conclusions / Future Work
George C. Marshall Space Fight Center
• Thermal simulator development is a "work in
progress" that is constantly being improved
• Work to-date has provided a database of options
(fabricability and performance) that can be called on
when a reactor design is finalized
• Current testing is being used to benchmark thermal
models
• Final simulator design will be specific to a given
reactor core design
SNC 2007, June 24-28, 2006
Acknowledgements
George C. Marshall Space Fight Center
• The work described within this report was supported by
NASA, in whole or part, as part of the program's technology
development and evaluation activities. Any opinions expressed
are those of the authors and do not necessarily reflect the
views of NASA.
SNC 2007, June 24-28, 2006
National AeronauUcs and
Space Adrrinlslration
Static Pin Performance Matching
George C. Marshall Space Fight Center
1.4
0.2
_;(------:10 __
'-:";'-;r--_
,Y(,"
,
_C1adOD
- -:I! - Normalized
Power
- +- .Coolant
930 "-~~=-=Fu-e""l--.----------------------T 1.6
Cente~ine
__FueIOD
~CladlD
920
910
840
860
900
850
g 890
~
~ 880
41
Q,
E 870
41
I-
830 -t----r---,-------,----.---,------r--.-----r---,----+ 0.0
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
Distance Along Fueled Section (normalized)
198 kWt, 0.86 kW/pin (nominal) I
SNC 2007, June 24-28, 2006
National Aeronautics and
Space Adrrinlstratlon
Axial Temperature Distribution
George C. Marshall Space Fight Center
...
GI
1.5 ~
o
D.
c:
.2
III
.!!!
IL
(ij
E
GI
fE
'tl
GI
.!::!(ij
E
o
z
1.0
0.5
•
'')(., ,
~--
_---;(•• __ ._.- •••)K••••••••
---
_.-
.-
840
880
890
850
900 -.-----------.,,--------------------, 2.0
--- Time 0, Shaped 0 (Fuel)
-- 1 min, Fuel
-..- 1 min, Solid Sim (0 fuel)
__ 1 min, Powder Sim (Q fuel)
-+- Time 0, Constant 0 (Sim)
-- 1 min, Solid Sim (Qe)
-- 1 min, Powder Sim (Qe)
···lIf·· Power at Time °2"
-~ 870
~
GI
~ 860
830 -j-------,--------,--------r--------,-------+ 0,0
o 0.2 0.4 0.6 0.8 1
Distance Along Fueled Section (normalized)
SNC 2007, June 24-28,2006


Development of High Fidelity, Fuel-Like Thermal Simulators for Non-Nuclear Testing

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server