W. T. Shmayda, N. P. Redden, R. F. EarleyUniversity of RochesterLaboratory for Laser Energetics
Enhancing Gas Chromatography Performance
1
Tritium Focus Group-SandiaAlbuquerque, NM
22–25 October 2018
E28000
2
• Thermal conductivity and tritium monitor detector measurements are complementary and predict similar atom fractions in H/D/T mixtures within 1%
• Miniaturization of the pressure sensing detector and the effluent isolation valve will reduce DT injection quantities for assay by 60%
• LLE has analyzed two of the three inactive gas samples provided by Sandia National Laboratories as part of the round robin exercise to compare assay results across the complex
Outline/Summary
Filling cryogenic targets in the permeation cell is a multistep process
G6218r
5
DT High-Pressure System (DTHPS) Glovebox
Tertiary containment
Syringe pump
Cryostat
FTS Glovebox
To tritium removal system
TFS Glovebox
USB 2 Assay
USB 1
DTHPScondensation
tube
High-pressure
guage Permeation cell
Condensationtube
P/Ddiffuser
TFS: Tritium Fill StationUSB: uranium storage bedFTS: Fill/Transfer Station
The lighter isotopic species concentrate whilepressurizing the permeator in the Tritium Fill Station
E25066c
6
Medium-pressuresystem
High-pressuresystem
T/D = 1.62
T/D = 1.60T/D = 1.62
PermeatorDiaphragmcompressor
TFS
T/D = 2.33
Composition in %: H/D/T
Variation in T/D downstream of the TFS = 1.2%
Gas chromatography uses iron-doped alumina at 77 K to separate the hydrogen isotopologues
E26599b
3
Minimum aliquot size: 80 nLError:
– systematic 1.2% – relative (peak to peak) <0.5% – reproducibility <0.2%
Fe-dopedMS 5 ÅLN2
Helium
Helium
MS 5 Å80°C
NeonTCD
Sample
Vacuum
Neon
P
TM
TCD
MS: molecular sieve TM: tritium monitor TCD: thermal conductivity detector
The assaying process requires four steps; first step: evacuate the injection volume
E26599c
4
Fe-dopedMS 5 ÅLN2
Helium
Helium
MS 5 Å80°C
NeonTCD
SampleVacuum
Neon
P
TM
TCD
To effluent capture
To effluent capture
Pump
Fe-dopedMS 5 ÅLN2
Helium
Helium
MS 5 Å80°C
NeonTCD
SampleVacuum
Neon
P
TM
TCD
To effluent capture
To effluent capture
Pump
Second step: charge the loop with a predefined aliquot of gas
E26599d
5
Minimum aliquot size: 80 nL
VacuumTo effluent capture
Pump
Fe-dopedMS 5 ÅLN2
Helium
Helium
MS 5 Å80°C
NeonTCD
Sample
Neon
P
TM
TCD
To effluent capture
Third step: inject the aliquot into the separation column and detection circuit
E26599e
6
Fourth step: sample analysis
E28005
7
00.0
2.5
5.0
7.5
2 4Time (min)
O2 CH4
COSign
al (m
V)
6 8
Fe-dopedMS 5 ÅLN2
Helium
Helium
MS 5 Å80°C
NeonTCD
Sample
Vacuum
Neon
P
TM
TCD
To effluent capture
To effluent capture
0
3
6
9
Sig
nal
(V)
Time (min)0 20 40
50% T91% T
T2
HTDT
Time (min)0
0
1
2
20
H2T2
HT
HD
5.45% H60.62% D33.93% T
40
Det
ecto
r sig
nal (n
V)
60
D2 DT
The 4-cm3 tritium monitor and thermal conductivity agree within 1% over all T/D ratios
E28001
8
1.04
1.03
1.02
1.01
1.00
0.99
0.98
0.97
0.960 10 20 30 40 50 60 70 80 90 100Tritium fraction from thermal conductivity detector
TCD error: !1.5%
Triti
um m
onito
r/the
rmal
con
duct
ivity
The minimum aliquot required for analysis by the TM is 0.01 nL.The gas inventory of a typical target is ~20 nL!
Sample
Vacuum
Neon
PDiaphragm
MKSbaratrongauge
Hand weld Microweld
Microweld
0.125
Hand weld
SS-4-VCR-1
Hand weld
6LV-4-VCR-3S-4TB7
SS-4BK-TW-1Cwith Cu STEM
60% of the gas delivered to the gas chromatograph is not used for analysis
E28002
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Injection loop volume: 1.5 mLPressure transducer andisolation valve volume: ~2.24 mLVolume injected for assay: 3.74 mL (4.84 Ci)
Selector valvePressuretransducer
Backup 4B safetyisolation valve
0Pressure (Torr)
200 400 600 800 10000
20
40
60
80
Volta
ge (m
VDC)
Voltage (mVDC) = 0.0762 P(Torr) –2.369R2 = 0.9997
The volume of the pressure detector and isolation valve assembly has been miniaturized ~200 fold
E28003
10
Injection loop volume: 1.5 mLPressure transducer andisolation valve volume: <10 nLVolume injected for assay: ~1.5 mL (1.9 Ci)
Tritium interacts with stainless steel to generate CH4 and CO
E26600a
11
Impurity growth rateVessel ID CH4 CO677 21.2 14.3624 1.9 6.0
* Time after filling the sample vessel
00
30
60
90
120
150
2Time (min)
Sig
nal
(m
V/s
cc)
4
544 ppm 307 ppm265 ppm
60 ppmCO CO390 ppm
64 ppm169 ppm33 ppm
Vessel ID 677 Vessel ID 625
6 8 00
30
60
90
120
150
2Time (min)
4 6 8
51 h*601 h
66 h*602 h
CH4 CH4
0
2
1
3
Pro
tiu
m c
on
cen
trat
ion
in f
uel
(%)
0 600
Duration since purifying fuel (days)
1200
H2O
H2O
H2O
H2O
H2O
H2O
H2O
H2O
H2OHO
HO
Evacuated
Absorbedwater layer
Bulkmetal
Baked
Tritiumconditioned
HOH
M
M
M
M
M
HH
H
H
HO
HO
HO
HO
HO
HO
HO
H2O
H2O
HTOTO
HO
TO
TO
HOHTO
HM
M
M
M
M
HH
H
H
TM
M
M
M
M
HT
H
T
Assay vessel1.88 %/mo
Permeation cell
Contamination caused by
sample vessel
“D” and “T” exchange with adsorbed water layers on the inner surfaces of the sample vessel and the process loop
E26601b
12
• Direct measurement of the protium content in a gas contained in unconditioned vessels leads to 300% errors in the protium fraction
LLE is participating in the national lab round robin gas-analysis exercise
E28004
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SampleID Composition Nominal
mixture (%)Measured
valueRSD*(%)
1 H2 35 42.95 0.11HD – 3.01 0.80D2 65 54.04 0.05H/D 53.8 80.02 0.16
3 H2 20 30.02 0.02HD – 44.30 0.06D2 20 25.50 0.01H/D 1 1.10 0.06
* Relative standard deviation
The isotopologue ‘HD’ dominates the H2/D2 spectrum in the Mass Cal Gas sample
2525 202015 1510 105 5
300
150
10
5
Time (min)Time (min)
Sign
al (m
V) H2
H2
D2
D2
HD
HD
Sample #1 (H2/D2) Sample #3 (Mass Cal Gas)
Need to run a calibration gas to confirm the locations of the non-hydrogenic species
1
0.5
Sign
al (V)
642Time (min)
H2
N2
CH4COorAr
This column can not identify CO2
Composition of Mass Cal Gas• H2• D2• N2• Ar• CH4• CO2
E28000
14
Outline/Summary
• Thermal conductivity and tritium monitor detector measurements are complementary and predict similar atom fractions in H/D/T mixtures within 1%
• Miniaturization of the pressure sensing detector and the effluent isolation valve will reduce DT injection quantities for assay by 60%
• LLE has analyzed two of the three inactive gas samples provided by Sandia National Laboratories as part of the round robin exercise to compare assay results across the complex
