Influence of molten salt composition on the fluorination of UF4

Article abstract of DOI:10.1016/j.jfluchem.2018.11.015

The fluorination of UF₄ by F₂ in LiF-NaF-KF(46.5-11.5-42 mol%, FLiNaK), FLiNaK-ThF₄(88.0–12.0 mol.%) and KF-ZrF₄(58–42 mol%, FKZr) at 550 °C was investigated, and the results indicated the conversion rate of UF₄ to UF₆ was different in FLiNaK with the other two molten salts. Raman spectroscopy and X-ray diffraction (XRD) were used to study the influence of the fluoroacidity on the coordination structure of Zr (IV) and U(IV) in FLiNaK with various contents of ZrF₄. The results indicated that the concentration of free F^? decreased and the molten salt became more acidic with the increase of ZrF₄ content. The main Zr(IV) complex present changed from ZrF₇^3?, ZrF₆^2? to ZrF₅^? as the U(IV) complex changed from UF₈^4? or UF₇^3? to UF₆^2?. The fluorination of UF₄ in FLiNaK with various fluoroacidity suggested that a higher fluoroacidity of molten salts resulted in relatively low coordination numbers of Zr-F and U-F, a higher conversion rate and average reaction rate of UF₄ to UF₆, and less corrosive of the structural material.

Full text of DOI:10.1016/j.jfluchem.2018.11.015

JournalofFluorineChemistry218(2019)99–104
Contents lists available at ScienceDirect
Journal of Fluorine Chemistry
journal homepage: www.elsevier.com/locate/fluor
Influence of molten salt composition on the fluorination of UF4
⁎
Lixin Suna,b,1, Yongsheng Niua,b,1, Congwei Hua,b, Chenyang Wanga,b, Qiang Doua,b,
,
⁎
Qingnuan Lia,b,
a Shanghai Institute of Applied Physics, Chinese Academy of Science, Shanghai 201800, China
b Center of Excellence TMSR Energy System, Chinese Academy of Sciences, Shanghai 201800, China
A R T I C L E I N F O
A B S T R A C T
Keywords:
The fluorination of UF4 by F2 in LiF-NaF-KF(46.5-11.5-42 mol%, FLiNaK), FLiNaK-ThF4(88.0–12.0 mol.%) and
KF-ZrF4(58–42 mol%, FKZr) at 550 °C was investigated, and the results indicated the conversion rate of UF4 to
UF6 was different in FLiNaK with the other two molten salts. Raman spectroscopy and X-ray diffraction (XRD)
were used to study the influence of the fluoroacidity on the coordination structure of Zr (IV) and U(IV) in FLiNaK
with various contents of ZrF4. The results indicated that the concentration of free F− decreased and the molten
salt became more acidic with the increase of ZrF4 content. The main Zr(IV) complex present changed from
ZrF73−, ZrF62− to ZrF5− as the U(IV) complex changed from UF84− or UF73− to UF62−. The fluorination of UF4
in FLiNaK with various fluoroacidity suggested that a higher fluoroacidity of molten salts resulted in relatively
low coordination numbers of Zr-F and U-F, a higher conversion rate and average reaction rate of UF4 to UF6, and
less corrosive of the structural material.
Molten salt
Fluorination
Fluoroacidity
Coordination structure
FLiNaK
UF4
1. Introduction
and the fluoride volatility method (FVM) has been proposed [6–9]. The
FVM can separate UF4 in molten salt by transforming it into volatile
The molten salt reactor (MSR) is one of the most promising
Generation IV Nuclear Energy Systems because of its unique fuel cycle
capabilities and safety characteristics [1], and it is also recognized as an
ideal reactor to implement the thorium-uranium fuel cycle [2]. The fuel
salt selected for MSR should meet requirements such as specific neu-
tronic, thermal, transport and chemical properties and low fuel and
processing costs [1], and fluoride salts are the main choice due to their
favorable properties. For example, the Aircraft Reactor Experiment
(ARE) developed at Oak Ridge National Laboratory (ORNL) used NaF-
ZrF4-UF4 (53-41-6 mol.%) as fuel. The fuel for the Molten Salt Reactor
Experiment (MSRE) was LiF-BeF2-ZrF4-UF4 (65-29-5-1 mol.%). In the
design of Molten Salt Breeder Reactor (MSBR), LiF-BeF2-ThF4-UF4 (72-
16-12-0.4 mol.%) was proposed [3]. Molten Salt Fast Reactor (MSFR)
was supposed to be fueled with LiF–ThF4–UF4 (77.5-20-2.5 mol.%) [4].
The selection of fuel carrier in the design of MOlten Salt Actinide Re-
cycler and Transmuter (MOSART) included LiF-BeF2 (73-27 mol.%),
LiF-NaF-BeF2 (15-58-27 mol.%) and LiF-NaF-KF (38-9-46 mol.%) [5].
Due to the characteristics of the thorium–uranium fuel cycle, on-line
or off-line fuel reprocessing should be employed to realize effective
utilization of thorium in MSR. In the reprocessing flowsheets designed
for the thorium-based MSR (TMSR), uranium separation is the first step,
UF6, and most of the other non-volatile fission products remain in the
molten salt. The advantages of FVM include the small volume of fission
product waste, convenient form of the UF6 product, virtual elimination
of processing criticality hazards and high decontamination factors of
the UF6 product [10]. During the 1950s and 1960s, ORNL adopted FVM
to treat ARE fuel (NaF-ZrF4-UF4, 53-41-6 mol.%) and zirconium-ur-
anium alloy fuel in NaF-LiF-ZrF4 (34-26-40 mol.%), and found the
conversion of UF4 to UF6 in both treatments reached up to 99.9% with a
fluorine utilization of 25% and 5.7%, respectively [11–13]. ORNL re-
searchers attributed the difference in the fluorine utilization to the
geometry of the fluorinator; however, the difference in the molten salt
components might also have an influence on fluorination. Un-
fortunately, until now, there have not been reported on how the com-
position of the fuel salt affects the fluorination process of UF4 in a
molten salt.
Many studies have indicated that the fluoroacidity will affect or
change the physico-chemical properties of fluoride salts, such as the
viscosity, solubility, volatility, chemical reactivity and electrochemical
properties [14,15]. Grande et al. [16] studied ZrF4-BaF2 and de-
termined that the viscosity and density of the molten salt increased with
the increase of BaF2 content, which was attributed to the formation of
⁎ Corresponding authors at: Shanghai Institute of Applied Physics, Chinese Academy of Science, Shanghai 201800, China.
E-mail addresses: douqiang@sinap.ac.cn (Q. Dou), liqingnuan@sinap.ac.cn (Q. Li).
1 Lixin Sun and Yongsheng Niu have contributed equally on this work.
https://doi.org/10.1016/j.jfluchem.2018.11.015
Received 11 June 2018; Received in revised form 30 September 2018; Accepted 26 November 2018
Availableonline11December2018
0022-1139/©2018ElsevierB.V.Allrightsreserved.

L. Sun et al.
JournalofFluorineChemistry218(2019)99–104
4−m
ZrF m
in the presence of free fluorine anions. In LiF-BeF2, the ba-
sicity increased with an increase in the LiF content, while the viscosity
decreased [17]. Bieber et al. [14] studied the stability of dissolved Si
(IV) ions in several alkaline fluoride molten salts and found that the
equilibrium between Si(IV) ions and SiF4(g) was highly influenced by
the relative fluoroacidity of the molten salt; i.e, the more free F- present
in a molten salt, the more stable the Si(IV) ions were and the less SiF4
was released. Conocar et al. [18,19] reported that the salt composition
and fluorobasicity would affect the activity coefficients and distribution
coefficients of actinides and lanthanides during a pyrochemical re-
ductive extraction process. Williams [17] pointed out that the corrosion
of Inconel was much more severe in FLiNaK than in NaF-ZrF4 due to the
increase in the stability of the corrosion product due to complexation
with the fluoride ions in FLiNaK. Williams et al. [20] also compared the
behavior of GaCl3 in both prototypical Lewis acid and Lewis base salts
and determined that the volatility of GaCl3 was suppressed in basic
molten salts while promoted in acidic molten salts. It is unclear that
whether the fluoroacidity of molten salts influences the fluorination
process of UF4.
Fig. 1. Schematic diagram of the device for fluorination of UF4.
for in situ monitoring of the fluorination process. The gas flow rate was
controlled and measured with thermal mass flowmeters (5850E, Ar,
range: 0.1–5SLM, uncertainty: 1% full scale; 5850 EM, F2/Ar range:
0.05–1SLM, uncertainty: 1% full scale Brooks, USA).
In this work, the fluorination of UF4 in different molten salts, in-
cluding LiF-NaF-KF(46.5–11.5–42 mol.%, FLiNaK), KF-ZrF4 (58-42 mol.
%, FKZr), FLiNaK-ThF4(88.0-12.0 mol.%) was carried out, and the re-
sults were compared. Furthermore, in order to study the effect of the
fluoroacidity on the fluorination of UF4, various amounts of ZrF4 were
added to change the fluoroacidity of FLiNaK. To illuminate the influ-
ence mechanisms of fluoroacidity on the fluorination of UF4, the co-
ordination structure of U(Ⅳ) in FLiNaK with various ZrF4 contents was
studied using Raman spectroscopy and X-ray diffraction (XRD).
The general experimental procedure for the fluorination was as
follows: approximately 30 g of FliNaK-UF4, FLiNaK-UF4-ThF4, FKZr-
UF4, or FLiNaK-ZrF4-UF4 powder was placed in a nickel crucible, which
was subsequently loaded into the fluorinator. After the fluorinator was
sealed, it was heated to 550 °C and kept at that temperature for 2 h. All
the gas pipelines and valves were heated and maintained at 80–100 °C
to avoid the deposition of UF6. Then, F2/Ar gas was introduced into the
molten salt at a flow rate of 0.1 L/min. The gas leaving the fluorinator
passed through the NaF absorbers at 100 °C, at where the UF6 was
absorbed, and then flowed through an activated alumina absorber and
aqueous KOH-KI scrubber to absorb any residual UF6 and neutralize
excess fluorine, respectively. FTIR was used to detect the gas out of the
fluorinator, and the reaction was stopped when the UF6 concentration
was below the detection limit of the FTIR.
2. Experimental
2.1. Reagents and materials
FLiNaK (LiF-NaF-KF:46.5-11.5-42 mol.%) and FKZr (KF-ZrF4:58-
42 mol.%) molten salts were supplied by Shanghai Institute of Organic
Chemistry, Chinese Academy of Science (CAS) [21]. UF4 (99.9%, de-
pleted uranium, the abundance of 235U is less than 0.3%) was supplied
by China National Nuclear Corporation and used without further pur-
ification. ThF4 (99.99%) was prepared by Changchun Institute of Ap-
plied Chemistry, CAS and used without further purification. ZrF4
(99.9%) was purchased from Sigma-Aldrich Co., Ltd. And was dehy-
drated for 20 h at 200 °C before use. F2-Ar mixed gas (20–80 vol.%,
written as F2/Ar) was purchased from Tianjin Changlu Huaxin Che-
mical Co., Ltd. and contained impurities of air < 0.05 vol.%,
CF4 < 0.01 vol.% and HF < 0.37 vol.%.
2.4. Analysis instrument and method
The uranium and nickel contents in the salt samples before and after
fluorination were analyzed by inductively coupled plasma mass spec-
trometry (ICP-MS, NexION 300D, PerkinElmer). The salt was sampled
in liquid state and ground after solidification in an argon covered glove-
box. Then certain amount of salt samples was dissolved in about 5 ml
HNO3(4 M) solution at 150 ℃, and contents of U、Ni and other ele-
ments were analyzed by ICP-MS.
XRD (X' Pert Pro MPD, PANalytical) equipped with Cu (40 kV,
30 mA) source was employed to characterize the species of Zr(Ⅳ) and U
(Ⅳ) in salts. The salt was also sampled in liquid state and ground after
solidification in an argon covered glove-box. The X'Pert HighScore
database and software were used for pattern-matching.
2.2. Molten salt preparation
The molten salt preparation was carried out in a homemade elec-
trical furnace (maximum temperature: 1000 °C connected to an argon-
covered glovebox. Details of this equipment have been reported pre-
viously [22]. Certain amounts of fluorides (UF4, ThF4 and ZrF4) were
mixed with the FLiNaK or FKZr eutectic in a nickel crucible (Ni purity＞
99.96%, Sinopharm Chemical Reagent Co., Ltd.), which was placed
inside the furnace vessel. After the vessel was sealed by covering the lid
and screwing tight, it was first heated to 250 °C and maintained for 2 h
to remove trace moisture. Then, the furnace was heated up to 750 °C
and kept at that temperature for 15 h. The prepared molten salt was
naturally cooled.
Raman spectroscopy (LabRAM HR, HORIBA Jobin Yvon) was also
performed to identify the species of salt. The 532 nm line of an argon
ion laser with 100 mW average power was used for exciting the sample.
The solid salt sample was put in a ceramic furnace and the laser was
focused on the sample through a water-cooled silica window. The in-
tegral time is 20 s, the integral number is 50 times.
3. Results and discussion
2.3. Fluorination of UF4 in different molten salts
3.1. The fluorination of UF4 in different molten salts
The experiments were conducted in the device illustrated in Fig. 1.
The fluorination system consisted of a fluorinator, NaF absorbers, off-
gas treatment apparatus, gas pipelines and valves. Fourier transform
infrared spectroscopy (FTIR, Spectrum Two™, Perkin, USA) was used
The fluorination of UF4 in different molten salts, including FLiNaK
(LiF-NaF-KF-UF4: 46.4-11.5-41.9-0.24 mol.%), FKZr (KF-ZrF4-UF4:
57.6-41.7-0.64 mol.%), FLiNaK-ThF4 (LiF-NaF-KF-ThF4-UF4: 40.7-10.1-
36.8-12.0-0.43 mol.%) was carried out under the same conditions, and
100

L. Sun et al.
JournalofFluorineChemistry218(2019)99–104
Table 1
The results of fluorination in different molten salts.
The molten salts
U (wt%)
Fluorination time (min)
Conversion rate of UF4 (%)
Average rate of fluorination (gUF4/h)
Before
After
FLiNaK
1.37
1.87
1.46
0.07
0.13
0.12
1.35
1.70
42
0.10
0.07
120
80
/
/
FLiNaK-ThF4
FKZr
9.1
99.7
0.05
0.69
9 ppm
50
Fig. 2. FTIR results for fluorination in FLiNaK at specific time in 120 min. (a) and the relative concentration of UF6 in the gas from the fluorinator at various
fluorination times FLiNaK-ThF4 (b) and FKZr (c).
the results of the fluorination are listed in Table 1. For the FLiNaK
molten salt, almost no UF6 was detected during the whole reaction
period. Fig. 2a shows the FTIR spectrum of the gas leaving the fluor-
inator in 120 min, and the ICP-MS analysis also indicated that the
concentration of uranium in the salt did not changed after the reaction.
In the case of FLiNaK-ThF4, UF6 was detected by FTIR at 25 min (as
shown in Fig. 2b), but the fluorination rate was very slow during the 80-
min’s fluorination process. The conversion rate and average reaction
rate of UF4 were only approximately 9.1% and 0.05 g UF4/h, respec-
tively. The fluorination of UF4 in FKZr was also carried out under the
same reaction conditions, as shown in Fig. 2c. UF6 was detected at
10 min, and the UF6 concentration in the gas increased gradually and
reached a maximum value at approximately 27 min. The concentration
of uranium in the molten salt was reduced from 1.46 wt.% to 42 ppm
after 50 min of fluorination. The conversion rate of UF4 was greater
than 99.7% and the average reaction rate was approximately 0.69
gUF4/h.
(Ⅳ) with F− in FLiNaK-ThF4 reduced the concentration of “free”
fluoride ions. In FKZr, almost all the fluoride ions are coordinated with
Zr(Ⅳ) ions, and no “free” fluoride ions exist in the salt. According to the
definition of fluoroacidity, the lower the “free” F− concentration is, the
less basic the molten salt is. We speculated that the difference in
fluoroacidity was the major factor causing the difference of UF4 fluor-
ination behavior in the three molten salts.
3.2. The effect of fluoroacidity on the coordination structure of U(IV) in
FLiNaK with various contents of ZrF4
To confirm the above speculation and reveal the influence me-
chanism of the fluoroacidity on the fluorination of UF4, various
amounts of ZrF4 were added to FLiNaK to obtain the molten salts with
different fluroacidities.
XRD analysis of FLiNaK with contents of ZrF4 ranging from 5.8 to
27 mol.% was performed to determine the coordination form of Zr-F
and “relative” fluoroacidity of the molten salts, and the results are
shown in Fig. 3 and Table 2. With the addition of ZrF4, K3ZrF7 appeared
Among the three molten salts studied, FLiNaK is a typical basic salt
solution, and all fluoride ions are “free”. The strong interaction of Th
101

L. Sun et al.
JournalofFluorineChemistry218(2019)99–104
3−
the main Zr(IV) complex present changed from ZrF7 to ZrF5−. With
the addition of UF4, the formation of U-F coordination complexes either
reduced the concentration of relatively “free” fluoride ions or competed
with the coordination of Zr-F, which reduced the coordination number
−
2−
of Zr-F. Thus ZrF5 became the main species instead of ZrF6
in
FLiNaK-ZrF4. The results from the XRD analysis of FLiNaK-ZrF4 with or
without UF4 indicated the coordination distribution of Zr(IV) will
change with the change in the fluoroacidity, and a higher fluoroacidity
results in a relatively lower coordination number. We believe that the
coordination number of U(IV) should also be lower in the higher
fluoroacidity. Toth et al. [24] also reported that the coordination
number of U(IV) varied with the change in the F- concentration, as
shown in Eq. (1). Unfortunately, no other information on U(IV) except
2−
UF6
was found in the XRD results of our experiments.
3
4
UF 2 + F
UF7 + F
UF8
(1)
6
The Raman spectra of FLiNaK with various contents of ZrF4 and a
fixed content of UF4 were also measured at room temperature to obtain
more information about the coordination structures of Zr(Ⅳ) and U(Ⅳ),
and the results are shown in Fig. 5. With the content of ZrF4 below
9.6 mol.%, two bands were observed at 509 cm−1 and 545 cm−1. The
band at 545 cm−1 was assigned to the mode of the ZrF73- complex [25],
Fig. 3. XRD spectra of FLiNaK with various contents of ZrF4.
while the band at 509 cm−1 can be attributed to a UFx4-x complex, such
Table 2
3−
as UF7
or UF84−. With the increase in the ZrF4 content, the band
The identified species in FLiNaK with various contents of ZrF4.
shifted from 545 cm−1 to 587 cm−1 first, and then further shifted from
587 cm−1 to 595 cm−1. The band at 587 cm−1 was assigned to the
mode of the ZrF62− complex [25,26], and the band at 595 cm−1 can be
attributed to ZrF5− according to the XRD results. In addition, when the
No. The concentration of ZrF4
Species
(mol.%)
LiF
NaF KF
K3ZrF7 Li3ZrF7 LiKZrF6
ZrF4 content was above 13.5 mol.%, the band at 509 cm−1 shifted to
0#
0
++ ++ ++
N
N
N
2# 5.8
3# 9.6
4# 13.5
5# 19.8
6# 27.0
++ ++ ++ ++
++ ++ ++ ++
N
N
487 cm−1, which might be due to the mode of the UF6
complex ac-
2−
N
N
cording to XRD results.
+
+
+
+
N
+
N
++
+
N
N
+
++
+
++
N
N
+
3.3. The effect of fluoroacidity on the fluorination of UF4 in FLiNaK with
various contents of ZrF4
Note: ++- obvious; +-weak; N-not found.
The fluorination experiments were carried out in FLiNaK with var-
ious content of ZrF4 and approximately 0.2 mol.% of UF4. The results
are listed in Table 4. The concentration of UF6 in the gas flow from the
fluorinator at various times were detected by FTIR.
with the originally added species (KF, LiF and NaF), and when the
concentration of ZrF4 was above 19.8 mol.%, two new species, K3ZrF7
and LiKZrF6, appeared. Meanwhile, the peak intensity of the originally
added species decreased with the addition of ZrF4, and no peaks of KF
and NaF could be found when the concentration of ZrF4 was more than
In FLiNaK with content of ZrF4 from 2.7 to 13.5 mol.%, no UF6 was
detected by FTIR during the whole fluorination process. The ICP-MS
analysis also indicated the concentrations of uranium in the molten
salts did not change before and after the 50-min’s fluorination process.
In FLiNaK with content of ZrF4 above 19.8 mol.%, UF6 was detected at
approximately 10–20 min. The concentrations of uranium in the molten
salt were reduced from 1.41 wt.% to 0.85 wt% and from 1.37 wt.% to
5.6 ppm for the molten salts with content of ZrF4 of 19.8 mol.% and
27 mol.%, respectively. Fig. 6 shows that the relative concentration of
UF6 in the gas from the fluorinator was maintained at a low level during
the fluorination process and increased with the increase of content of
ZrF4. Table 4 lists the conversion rates and average reaction rates of UF4
and shows that the rates increased with the increase in the ZrF4 content,
and both were low when the content of ZrF4 was less than 19.8 mol.%.
When the ZrF4 concentration was 27.0 mol.%, the conversion rate of
UF4 was greater than 99.9% and the average reaction rate was ap-
proximately 0.65 g UF4/h, which was similar to that of the reaction in
FKZr. Combined with the XRD and Raman results, these results illus-
trate that the fluoroacidity of the molten salt does influence the fluor-
ination behavior of UF4 by influencing the coordination distribution of
19.8 mol.%, which meant the fluoroacidity increased. As the ZrF4 mole
2−
fraction increased up to 27 mol.%, the intensity of ZrF6
became
stronger. Phifer et al. [23] also found the coordination number of Zr(IV)
decreased with an increase in the ZrF4 mole fraction in LiF-NaF.
To study the influence of the fluoroacidity of the molten salt on the
coordination structure of U(IV), 6.0 mol.% UF4 was added to FLiNaK
with different contents of ZrF4, from 5.8 to 27 mol.%. An XRD analysis
of the molten salt was performed, and the results are shown in Table 3
and Fig. 4
As shown in Fig. 4, for FLiNaK with 5.8 mol.% ZrF4, the species were
KF, LiF, NaF and K3ZrF7. The peaks for K2UF6 appeared and their in-
tensity increased when the content of ZrF4 was above 19.8 mol.%, while
Table 3
The identified species in FLiNaK with various contents of ZrF4 and a fixed
content of UF4.
No. Concentration of ZrF4
Species
(mol.%)
U(IV).
A higher fluoroaicity results in a higher conversion rate
LiF NaF KF K3ZrF7 KZrF5 K2UF6 LiKZrF6
(Table 5).
2# 5.8
√
√
√
√
√
√
N
N
√
√
√
N
√
√
√
N
√
√
√
Corrosion of the structural material of the fluorinator is one of the
main problems in the practical application of FVM. In this study, to
compare the effect of the molten salt components on the corrosion of
the fluorinator, the concentrations of the corrosion product, i.e., Ni, in
the different molten salts after fluorination were also analyzed by ICP-
4# 13.5
5# 19.8
6# 27.0
√
N
N
N
√
N
N
N
N
Note: N-not found.
102

L. Sun et al.
JournalofFluorineChemistry218(2019)99–104
Fig. 4. XRD spectra of FLiNaK with various contents of ZrF4 and a fixed content of UF4.
Fig. 5. Raman spectra of FLiNaK with various contents of ZrF4 and a fixed
content of UF4 at room temperature.
Fig. 6. The relative concentration of UF6 in the gas from the fluorinator at
various times.
MS, and the results are shown in Table 5. As shown in Table 5, the Ni
concentration in the molten salt decreased with the increase in the ZrF4
content, which indicated a higher fluoroacidity results in a less corro-
sive molten salt. Williams et al. [17] also found less severe corrosion in
a basic molten salt, and they explained that the stability of the corrosion
product was increased by complexation with active fluoride ions in the
basic molten salt. Based on the above findings, we conclude that the
fluoroacidity or composition of a molten salt influences the reactions of
UF4 and F2 and the corrosion degree of the structural material.
4. Conclusions
Fluorination experiments of UF4 in different molten salts, including
FLiNaK, FKZr and FLiNaK-ThF4, were performed at 550 °C, and the
results indicated that the composition of the molten salts affected the
fluorination process, i.e., the conversion rate and average reaction rate
of UF4 to UF6 was in the following order: FLiNaK < FLiNaK-
ThF4 < FKZr. The study of the effect of the fluoroacidity on the co-
ordination structure of Zr(IV) and U(IV) in FLiNaK with various
Table 4
The results for 50-min’s fluorination process in different molten salts.
No.
Concentration of ZrF4 (mol.%)
U (wt%)
Conversion rate of UF4 (%)
Average rate of fluorination (g UF4/h)
Before
After
1#
2#
3#
4#
5#
6#
7#
2.7
1.28
0.99
0.79
1.30
1.41
1.37
1.46
0.15
0.08
0.11
0.08
0.06
0.07
0.12
1.26
1.08
0.77
1.24
0.85
5.6
0.15
0.17
1.50
/
0.01
/
5.8
9.6
0.13
2.50
4.60
39.72
99.95
99.71
0.01
0.06
0.27
0.65
0.69
13.5
19.8
27.0
FKZr
0.04
0.1
1.4 ppm
9 ppm
42
103

L. Sun et al.
JournalofFluorineChemistry218(2019)99–104
Table 5
(2014) 421–429.
[5] V. Ignatiev, O. Feynberg, W. Maschek, Advanced Reactor Technology Options for
Utilization and Transmutation of Actinides in Spent Nuclear Fuel, IAEA, Vienna,
Austria, 2009.
The Ni concentration before and after fluorination in different molten salts.
No.
Concentration of ZrF4 (mol.%)
Ni (wt%)
[6] M. Rosenthal, The Development Status of Molten-Salt Breeder Reactors, ORNL-
4812, (1972).
Before
After
[7] L. Mathieu, D. Heuer, R. Brissot, C. Garzenne, C. Le Brun, D. Lecarpentier,
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2#
3#
5#
6#
7#
5.8
0.26
0.17
0.03
0.03
0.007
0.03
0.53
0.31
0.20
0.09
0.07
0.04
0.03
0.06
0.01
0.01
9.6
0.05
0.01
0.01
19.8
27
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FKZr
0.003
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Acknowledgments
This work was financially supported by the Strategic Priority
Research Program of the Chinese Academy of Sciences (Grant No.
XDA02030300), the Young Scientists Fund of the National Natural
Science Foundation of China (Grant No. 21501190), National Natural
Science Foundation of China (Grant No. 21601201), Youth Innovation
Promotion Association of the Chinese Academy of Sciences (Grant No.
2016241).
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