ASTM D8091-21
(Guide)Standard Guide for Impregnation of Graphite with Molten Salt
Standard Guide for Impregnation of Graphite with Molten Salt
SIGNIFICANCE AND USE
5.1 The molten salt reactor is a nuclear reactor which uses graphite as reflector and structural material and fluoride molten salt as coolant. The graphite components will be submerged in the molten salt during the lifetime of the reactor. The porous structure of graphite may lead to molten salt permeation, which can affect the thermal and mechanical properties of graphite. Consequently, it is important to assess the effect of impregnation of molten salt on the properties of the as-manufactured graphite material.
5.2 The purpose of this guide is to report considerations that should be included in the preparation of graphite specimens representative of that after exposure to a molten salt environment. The degree to which the molten salt will infiltrate the graphite will depend upon a number of factors, including the type of graphite and the type and extent of porosity, the properties of the molten salt, the impregnation pressure and temperature, and the duration of the exposure of the graphite to the molten salt.
5.3 The user of this guide will need to select impregnation parameters sufficiently representative of those in a molten salt reactor based on parameters provided by the designer. Alternatively, the user may select a standard set of impregnation conditions to allow comparisons across a range of graphites.
5.4 This guide is not intended to be prescriptive. A typical apparatus and associated procedure are described. Some indication of the sensitivity of the procedure to graphite type and impregnation conditions is given in He, et al.5
5.5 There are four major practical issues that must be addressed during the impregnation process:
5.5.1 The density of molten salt is greater than that of graphite. A specially designed tool is required to submerge graphite samples in the molten salt during the impregnation process.
5.5.2 Some molten salts (for example, FLiBe) are poisonous and it is therefore necessary to provide containment by performing proced...
SCOPE
1.1 This guide covers procedures for the impregnation of graphite with molten salt under a consistent pressure and temperature. Such procedures are necessary if the user wishes to prepare graphite specimens for testing that represent material that has been exposed to a molten salt environment in a molten salt nuclear reactor. The user will need to ensure that impregnation temperature and pressure conditions reflect those pertaining to the molten salt environment, noting that the properties of the material will change once it becomes irradiated.
Note 1: The term impregnation is used throughout this guide as this is the correct term for the described process. Other terms such as infiltration and intrusion may be encountered by the user in other texts and the term intrusion is commonly used to describe penetration of open porosity in graphite in a molten salt reactor environment.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this guide.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
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This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D8091 − 21
Standard Guide for
1
Impregnation of Graphite with Molten Salt
This standard is issued under the fixed designation D8091; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope* B923 Test Method for Metal Powder Skeletal Density by
Helium or Nitrogen Pycnometry
1.1 This guide covers procedures for the impregnation of
C559 Test Method for Bulk Density by Physical Measure-
graphite with molten salt under a consistent pressure and
ments of Manufactured Carbon and Graphite Articles
temperature. Such procedures are necessary if the user wishes
D7775 Guide for Measurements on Small Graphite Speci-
to prepare graphite specimens for testing that represent mate-
mens
rial that has been exposed to a molten salt environment in a
molten salt nuclear reactor. The user will need to ensure that
3. Terminology
impregnation temperature and pressure conditions reflect those
3.1 Definitions:
pertaining to the molten salt environment, noting that the
3.1.1 impregnation pressure (P ), n—the differential pres-
properties of the material will change once it becomes irradi-
I
sure between the cover gas pressure and the pore pressure of
ated.
the graphite specimen.
NOTE 1—The term impregnation is used throughout this guide as this is
3.1.1.1 Discussion—If the impregnation starts at a pore
the correct term for the described process. Other terms such as infiltration
pressure of atmospheric pressure, the impregnation pressure is
and intrusion may be encountered by the user in other texts and the term
the gauge pressure of the cover gas; if the impregnation starts
intrusion is commonly used to describe penetration of open porosity in
graphite in a molten salt reactor environment.
at a pore pressure of “0” (vacuum), the impregnation pressure
is the gauge pressure plus atmospheric pressure. For a pore
1.2 The values stated in SI units are to be regarded as
pressurebetween0andatmosphericpressure,theimpregnation
standard. No other units of measurement are included in this
pressure is (gauge pressure + atmospheric pressure – pore
guide.
pressure).
1.3 This standard does not purport to address all of the
3.1.2 impregnation temperature (T ), n—the system tem-
safety concerns, if any, associated with its use. It is the I
perature before the graphite specimen has been immersed in
responsibility of the user of this standard to establish appro-
the molten salt.
priate safety, health, and environmental practices and deter-
mine the applicability of regulatory limitations prior to use.
3.2 Definitions of Terms Specific to This Standard:
1.4 This international standard was developed in accor-
3.2.1 Parameter D ,n—a measure of the extent of penetra-
o
dance with internationally recognized principles on standard-
tion of the graphite porosity by the molten salt expressed in
ization established in the Decision on Principles for the
terms of the open pore volume of the specimen.
Development of International Standards, Guides and Recom-
3.2.1.1 Discussion—If there was no damage to the micro-
mendations issued by the World Trade Organization Technical
structure of the graphite during impregnation, then parameter
Barriers to Trade (TBT) Committee.
D based upon open pore volume would be unity at saturation.
o
This parameter is applicable when damage to the graphite
2. Referenced Documents
microstructure during impregnation is absent or low. Mercury
2
2.1 ASTM Standards:
porosimetry studies indicate that the threshold pressure for
microstructural damage is 13.8 MPa to 20.0 MPa (2000 psi to
3,4
3000 psi). This threshold should be used as a guide by users
1
This guide is under the jurisdiction of ASTM Committee D02 on Petroleum
when evaluating D . At high impregnation pressures, closed
o
Products, Liquid Fuels, and Lubricants and is the direct responsibility of Subcom-
porosity may be broken into by the molten salt and parameter
mittee D02.F0 on Manufactured Carbon and Graphite Products.
Current edition approved July 1, 2021. Published July 2021. Originally approved
in 2016. Last previous edition approved in 2016 as D8091 – 16. DOI: 10.1520/
3
D8091-21. Dickinson, J. M., Shore, J. W., “Observations Concerning the Determination of
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or Porosities in Graphites,” Carbon, Vol 6, 1968, pp. 937–941.
4
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Baker, D. J., Morris, J. B., “Structural
...
This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D8091 − 16 D8091 − 21
Standard Guide for
1
Impregnation of Graphite with Molten Salt
This standard is issued under the fixed designation D8091; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope Scope*
1.1 This guide covers procedures for the impregnation of graphite with molten salt under a consistent pressure and temperature.
Such procedures are necessary if the user wishes to prepare graphite specimens for testing that have represent material that has
been exposed to a molten salt environment that may not necessarily represent material exposed to an operating reactor
environment.in a molten salt nuclear reactor. The user will need to ensure that impregnation temperature and pressure conditions
reflect those pertaining to the molten salt environment, noting that the properties of the material will change once it becomes
irradiated.
NOTE 1—The term impregnation is used throughout this guide as this is the correct term for the described process. Other terms such as infiltration and
intrusion may be encountered by the user in other texts and the term intrusion is commonly used to describe penetration of open porosity in graphite in
a molten salt reactor environment.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this guide.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
1.4 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2
2.1 ASTM Standards:
B923 Test Method for Metal Powder Skeletal Density by Helium or Nitrogen Pycnometry
C559 Test Method for Bulk Density by Physical Measurements of Manufactured Carbon and Graphite Articles
D7775 Guide for Measurements on Small Graphite Specimens
3. Terminology
3.1 Definitions:
3.1.1 impregnation pressure (P ), n—the differential pressure of between the cover gas used in the impregnation.pressure and the
I
pore pressure of the graphite specimen.
1
This guide is under the jurisdiction of ASTM Committee D02 on Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of Subcommittee
D02.F0 on Manufactured Carbon and Graphite Products.
Current edition approved Dec. 1, 2016July 1, 2021. Published January 2017July 2021. Originally approved in 2016. Last previous edition approved in 2016 as D8091 – 16.
DOI: 10.1520/D8091-16.10.1520/D8091-21.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1
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D8091 − 21
3.1.1.1 Discussion—
If the impregnation starts at a pore pressure of atmospheric pressure, the impregnation pressure is the gauge pressure of the cover
gas; if the impregnation starts at a pore pressure of “0” (vacuum), the impregnation pressure is the gauge pressure plus atmospheric
pressure. For a pore pressure between 0 and atmospheric pressure, the impregnation pressure is (gauge pressure + atmospheric
pressure – pore pressure).
3.1.2 impregnation temperature (T ), n—the system temperature before the graphite samplespecimen has been immersed in the
I
molten salt.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 Parameter D—D , n—provides a measure of the extent of penetration of the graphite porosity by the molten salt. If there
o
was no damage to the microstructure of the graphite during impregnation, then parameter D based upon open pore volume would
be unity at saturation. At high impregnation pressu
...
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