Properties update: lbh15 linking

[fpepe-polito]

Up to now, coolant properties are computed and updated by means of linear
interpolation of tabulated values (ex. file lead.csv in the data folder)
or defined by the user in the input file.
All the tables in the data folder are obtained by means of correlations
[1], and properties are calculated at a few specific temperatures. The
following concerns have been identified:

• Since the temperature difference between successive values in tables is
  large (50 K), linear interpolation (as the one performed in the code) is
  less accurate.
• Some of the properties are given at temperatures outside of the validity
  range suggested for that specific correlation in [1]. In Tables 1-3,
  DASSH properties' range is compared to the validity range provided
  by the [2] for each correlation. Please, consider that information
  provided by the SCK reference coincides with those provided by the
  OECD/NEA Handbook [2].
• In Figure 1c, DASSH viscosity shows a discontinuous behavior, due to the
  approximation to 1e-3. Approximation in the tabulated values of viscosity
  leads to large relative errors when compared to the value given by the
  SCK correlation, as plotted in Figure 2.
• The values for the conductivity of LBE are not in accordance with the
  correlation in the reference, as shown in Figure 1d and Figure 3.

Given the issues presented above, linking DASSH to the properties' library
lbh15 [3] can be performed for lead, bismuth and LBE, in order to obtain more
accurate values for properties, to correct uncertain values (conductivity for
LBE) and to adhere to the correct validity ranges by providing a warning
each time the evaluation of the properties is required outside them.

LEAD	DASSH range [K]	Correlation NEA	Validity range [K]
Density	600 - 2000	Sobolev 2008a	600.60 - 2021
Specific heat	600 - 2000	gurvich1991	600.60 - 2000
Viscosity	600 - 2000	Sobolev 2007b	600.60 - 1473
Conductivity	600 - 2000	Sobolev 2007b	600.60 - 1300

Table 1: DASSH range of temperatures vs SCK vality range for lead properties.

LBE	DASSH range [K]	Correlation NEA	Validity range [K]
Density	400 - 1800	OECD/NEA Handbook	398 - 1927
Specific heat	400 - 1800	Sobolev 2011	400 - 1927
Viscosity	400 - 1800	Sobolev 2007b	398 - 1300
Conductivity	400 - 1800	Sobolev 2011	398 - 1200

Table 2: DASSH range of temperatures vs actual vality range for LBE properties.

BISMUTH	DASSH range [K]	Correlation NEA	Validity range [K]
Density	500 - 1800	Imbeni 1998a	544.60 - 1831
Specific heat	500 - 1800	Imbeni 1998a	544.60 - 1831
Viscosity	500 - 1800	Lucas 1984b	544.60 - 1300
Conductivity	500 - 1800	Touloukian 1970b	544.60 - 1000

Table 3: DASSH range of temperatures vs actual vality range for bismuth properties.

Figure 1: properties: DASSH vs lbh15.

Figure 2: viscosity relative error: DASSH vs lbh15.

Figure 3: thermal conductivity for LBE relative error: DASSH vs lbh15.

[1] https://inis.iaea.org/collection/NCLCollectionStore/_Public/43/095/43095088.pdf
[2] C. Fazio et Al. Handbook on Lead-bismuth Eutectic Alloy and Lead Properties,
Materials Compatibility, Thermal-hydraulics and Technologies. Technical Report No. 7268,
OECD/Nuclear Energy Agency (NEA), Paris, France, 2015. doi:10.1787/42dcd531-en.
[3] https://newcleo-dev-team.github.io/lbh15/