IEA Tritium and Safety Issues in LL Breeders, 11-12 June 2007, Idaho FallsO. GASTALDI
Associationwith Euratom
IEA Implementing Agreement on Nuclear Technology for Fusion ReactorsLiquid Breeder Blankets Subtask
Coordinating Meeting on R&D for Tritium and Safety Issues in Lead-Lithium Breeders 11-12 June 2007, Idaho Falls, ID, USA
LiPb specifications and the chemistry control
O. Gastaldi 1, L. Sedano2,
(1 CEA, 2 CIEMAT)
IEA Tritium and Safety Issues in LL Breeders, 11-12 June 2007, Idaho FallsO. GASTALDI
Associationwith Euratom
What are the main issues ?
Two kinds of problem must be solved in the field of LLE chemistry control:
– All teams involved in LLB studies must work with the same PbLi eutectic
specifications of the common eutectic %Li specifications of maximum impurities content
– During operation of TBM, the chemistry must be controlled
IEA Tritium and Safety Issues in LL Breeders, 11-12 June 2007, Idaho FallsO. GASTALDI
Associationwith Euratom
Summary Li-Pb eutectic (LLE) characteristics should be established according
to nuclear material QA requirements (ISO3131/- 1, /-5, Light Metals and light alloying metal: methods for processing and treatment) … as it will be demanded for the tons of TBM needs in ITER
QA demands to (LLE) refer to Constitutive and to Compositional characteristics
QA constitutive specifications apply for accurate Li title and control of Li structural micro-aggregation
Compositional specifications apply for impurity levels
Some key materials Fusion Technology properties can largely change through deviations (ex.: Li aggregation or Li in excess in an supposed eutectic can have a large effect on tritium solubility)
Production and material testing routes should be fixed according to QA standards
Lead-Lithium Eutectic QA as Nuclear Material
IEA Tritium and Safety Issues in LL Breeders, 11-12 June 2007, Idaho FallsO. GASTALDI
Associationwith Euratom
ElementContent (ppm)
Ag <1
Al 1
As 40
Au <1
Cr <3
Cu <1
Cd <1
Fe 13
Ga <1
Hg <1
In <1
Li 0.68%
Ni 7
P <10
Pb Balance
Sb <10
Su <5
Ti <10
Bi 0.02%
Some impurities typically linked to Lithium (1 ppm Al) might be used for a fast homogeneity test
Major interest is of course to minimize Bi content (below tenths ppb).
Compositional specifications apply for impurity levels
IEA Tritium and Safety Issues in LL Breeders, 11-12 June 2007, Idaho FallsO. GASTALDI
Associationwith Euratom
Figure 1: Phase diagram of Pb-Li system [Tegze and Hafner, 1989]
Y Ref. at.% Li Alloy origin T-control Analysis Uncertainties
88 [5] 16.98 CEA, Li(99.5) and Pb(99.994)
-- -- --
91 [6] 16.55 Alloyed at home Poor detail N.S.
91 [3] 16.98 laboratory, Li(99.4) from Metallgesellschaft with 0.5 Na, 0.01 K, 0.03 Ca,
<0.01 Al, <0.03 Si and Pb(99.99) from Ventron
Thermal analysis (Ni-
CrNi-thermocouples
) and thermal differential
analysis with a Netzsch DTA
AAS 0.01 wt.%, oxygen
impurities were below
the hot extraction
method (0.01%)
92 [7] 15.7 laboratory, use of an electromagnetic pump to ensure the homogeneity
measurement of electrical
resistance as a function of T
--
05 [10] 15.8 laboratory, use of a three-phase MHD stirrer. Comparison with a
sample from METEAUX-SPECIAUX (1993) and
another from Jost-Hinrich Stachov Metallhandel
(2003)
X-ray phase study,
AAS
1.3 at.%
06 [11] 16.97 laboratory, Li(99.8) and Pb(99.99)
-- 0.20 wt.%
LEAD-LITHIUM EUTECTIC TITTLE
Li chemical activity determine LLE activity: title has large impact on NFT.
Tritium solubility in LLE would largely depends on Li-disproportioning by bad mixing or local aggregation. Other properties less modified
2at% Li deviations are unacceptable from QA of LLE as Nuclear Material
IEA Tritium and Safety Issues in LL Breeders, 11-12 June 2007, Idaho FallsO. GASTALDI
Associationwith Euratom
- Errors in estimation depend on the experimental protocol for production and for its determination
-T data for a total of 52 points {0 < xLi (at%) <22.2}, show to decrease smoothly from the melting point of pure Pb to the eutectic point (15.7(2) at% Li, 235(1)°C, [P. Hubberstey et al, JNM (1992)],
- a single liquid phase maintained over the composition range from 13.7 to 18.0 at% Li, (33) eutectic d) eutectic disproportioningisproportioning
(())
Deviation from theoretical eutectic composition [15.7(2)at%Li] at liquid phase and solubility
impact with Li aggregation.- not systematically checked & driving potentially to incorrect overestimated solubility (in connection with Li-aggregation by clustering)
- Mixing light Li with heavy Pb and large homogeneity is not an easy technical mater
eut
LieutLiPbs Ks
KsLiatLiatLnK
)()).(..(1)( 17
LEAD-LITHIUM EUTECTIC TITTLE
Uncertainty in the eutectic eutectic composition (composition ( T-soly) T-soly)
Disproportioning by badDisproportioning by bad mixing (mixing ( T-soly) T-soly)
Disproportioning effects can be like this
IEA Tritium and Safety Issues in LL Breeders, 11-12 June 2007, Idaho FallsO. GASTALDI
Associationwith Euratom
It is the J-H Stachow GmB commercial alloy. Test performed by Freibergs (UPUL, Latvia) 2005 This eutectic has been used for solubility determinations (!!!!)
The practical situation when homogenity is checked !!!:
This eutectic is used in present irradiations LIBRETTO -4 (!!!!)
IEA Tritium and Safety Issues in LL Breeders, 11-12 June 2007, Idaho FallsO. GASTALDI
Associationwith Euratom
Li dosage control and MHD stirring technology seems needed for mixing
Feasibility at semi- industrial scale ?
Mixing drawbacks:
fast alloying rates and very difficult local temperature control
possibility of formation of hard melting Li5Pb2, LiPb, Li3Pb ( Higher Li activity so Tritium solubility higher than in the eutectic !!!! )
Different commercial production
IEA Tritium and Safety Issues in LL Breeders, 11-12 June 2007, Idaho FallsO. GASTALDI
Associationwith Euratom
Roadmap for Pb-Li eutectic QA guarantees
Revision of set of ISO norms (ISO3131/- 1, /-5, Light Metals and light alloying metal: methods for processing and treatment) in force for Nuclear Materials and IAEA Regulations.
Fixing Material specification in terms of: (1) maximum allowable impurity contents, (2) Li contents global deviations (ex. < ± 0.2 Li at%) and (3) homogeneity criteria (ex. maximum size and distribution of Li and other Li-Pb phases aggregates),
Establishment of a production route (with specification of endorsing ISOs) according to previous material QA criteria.
Establishment of set of certification tests for Material QA (fine calorimetry at eutectic, x-ray phase study, Atomic Absorptions Technique, …)
Lack of database reproducibility for key FT properties can not even more potentially be justified in terms of material uncertainties
IEA Tritium and Safety Issues in LL Breeders, 11-12 June 2007, Idaho FallsO. GASTALDI
Associationwith Euratom
During operations
What has to be controlled in LLE? – Control of impurities must be insured:
• In order to guarantee tritium inventory
• In order to allow a good analysis of experimental tests
• In order to avoid precipitations
– Dynamic control of Li content
– Follow-up of tritium concentration
IEA Tritium and Safety Issues in LL Breeders, 11-12 June 2007, Idaho FallsO. GASTALDI
Associationwith Euratom
During operations
What is needed in term of measurement tools:– For oxygen: Technology is known (electrochemical
probes): validation in real conditions (flow rate mainly, magnetic field,…) must be checked
– For tritium:• Specific constraints:
– Small variation of tritium in LiPb at each pass in the TBM
– Short duration of pulses• Then dynamic measurement is needed (with good time
response)
IEA Tritium and Safety Issues in LL Breeders, 11-12 June 2007, Idaho FallsO. GASTALDI
Associationwith Euratom
During operations
Measurement tools:– For tritium:
• Existing tools:
– Use of permeator sensors
– Time response is too slow to insure dynamic follow-up of tritium content in TBM (need to
reach equilibrium)• What are the alternative solutions?
IEA Tritium and Safety Issues in LL Breeders, 11-12 June 2007, Idaho FallsO. GASTALDI
Associationwith Euratom
During operations
For impurities control what are the main issues:
– Li title adjustement (mainly for DEMO application) - Without doing agregates in order to guarantee homogeneous mixture
– Cold trap optimisation (mainly for DEMO application)
IEA Tritium and Safety Issues in LL Breeders, 11-12 June 2007, Idaho FallsO. GASTALDI
Associationwith Euratom
Main points to treat
Define a reference specifications for LLE composition (EU can propose it)
Define a production route with associated QA
Define develop and test tritium measurement tools (with short time response) efficient in realistic conditions (dynamic loop)
IEA Tritium and Safety Issues in LL Breeders, 11-12 June 2007, Idaho FallsO. GASTALDI
Associationwith Euratom
IEA Tritium and Safety Issues in LL Breeders, 11-12 June 2007, Idaho FallsO. GASTALDI
Associationwith Euratom
References
[33, Schulz,1986]
[55, Fauvet st Sannier, 1988]
[66, Reiter, 1991]
[77, Hubberstey, 1992]
[1010, Freibergs, 2005]
[1111, Stankus 2006]