ASTM C1671-07

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Designation:C1671 −07
StandardPractice for
Qualification and Acceptance of Boron Based Metallic
Neutron Absorbers for Nuclear Criticality Control for Dry
Cask Storage Systems and Transportation Packaging
This standard is issued under the fixed designation C1671; 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 E1461 Test Method for Thermal Diffusivity by the Flash
Method
1.1 This practice provides procedures for qualification and
acceptance of neutron absorber materials used to provide
3. Terminology
criticality control by absorbing thermal neutrons in systems
designed for nuclear fuel storage, transportation, or both. 3.1 Definitions:
3.1.1 acceptance test, n—for a neutron absorber material,
1.2 This practice is limited to neutron absorber materials
quality control, tests, and inspections conducted to determine
consisting of metal alloys, metal matrix composites (MMCs),
whether a specific production lot meets selected specified
and cermets, clad or unclad, containing the neutron absorber
material properties, characteristics, or both, so that the lot can
boron-10 ( B).
be accepted.
1.3 This standard does not purport to address all of the
3.1.2 areal density, n—for neutron absorber materials with
safety concerns, if any, associated with its use. It is the
flat parallel surfaces, the density of the neutron absorber times
responsibility of the user of this standard to establish appro-
the thickness of the material (g/cm ).
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use.
3.1.3 durability, n—the ability of neutron absorber materials
to withstand service conditions without physical changes that
2. Referenced Documents
would render them unable to perform their design functions.
2.1 ASTM Standards:
3.1.4 lot, n—aquantityofaproductormaterialaccumulated
B557 Test Methods for Tension Testing Wrought and Cast
under conditions that are considered uniform for sampling
Aluminum- and Magnesium-Alloy Products
purposes. E456
B557M Test Methods for Tension Testing Wrought and Cast
3.1.5 moderator, n—a material used to reduce neutron
Aluminum- and Magnesium-Alloy Products (Metric)
energy by scattering without appreciable capture.
C791 Test Methods for Chemical, Mass Spectrometric, and
3.1.6 neutron absorber, n—anuclidethathasalargethermal
Spectrochemical Analysis of Nuclear-Grade Boron Car-
neutron absorption cross section (also known as a neutron
bide
poison).
E8 Test Methods for Tension Testing of Metallic Materials
E21 TestMethodsforElevatedTemperatureTensionTestsof
3.1.7 neutron-absorber material, n—a compound, alloy,
Metallic Materials
composite or other material that contains a neutron absorber.
E456 Terminology Relating to Quality and Statistics
3.1.8 neutron attenuation test, n—for neutron absorber
E1225 Test Method for Thermal Conductivity of Solids by
materials, a process in which a material is placed in a thermal
Means of the Guarded-Comparative-Longitudinal Heat
neutron beam, and the number of neutrons transmitted through
Flow Technique
the material in a specified period of time is counted. The
neutron count can be converted to areal density by performing
the same test on a series of appropriate calibration standards
This practice is under the jurisdiction of ASTM Committee C26 on Nuclear
and comparing the results.
Fuel Cycle and is the direct responsibility of Subcommittee C26.03 on Neutron
Absorber Materials Specifications.
3.1.9 neutron cross section, [barn], n—a measure of the
Current edition approved July 15, 2007. Published August 2007. DOI: 10.1520/
probability that a neutron will interact with a nucleus in the
C1671-07.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or absorbing medium and is a function of the neutron energy.
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
3.1.10 open porosity, n—the volume fraction of all pores,
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. voids, and channels within a solid mass that are interconnected
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C1671−07
with each other and communicate with the external surface, such as during loading of fuel under water, or water ingress
and thus are measurable by gas or liquid penetration. C242, resulting from hypothetical accident conditions.
C21
4.6 The expected users of this standard include designers,
3.1.11 packaging, n—in transport of radioactive material,
neutron absorber material suppliers and purchasers, govern-
the assembly of components necessary to enclose the radioac-
ment agencies, consultants and utility owners. Adherence to
tive contents completely.
this standard does not guarantee regulatory approval; a gov-
ernment regulatory authority may require different tests or
3.1.12 probability sampling, n—a sample selection proce-
additional tests, and may impose limits or restrictions on the
dure in which the sampling units are selected by a chance
use of a neutron absorber material.
process such that, at each step of the selection, a specified
probability of selection can be attached to each sampling unit
5. Procedure
available for selection. E456
3.1.13 qualification, n—for neutron absorber materials, the 5.1 Determination of Service Conditions and Design Re-
process of evaluating, testing, or both, a material produced by
quirements for the Neutron Absorber Material—The designer
a specific manufacturing process to demonstrate uniformity
shall specify the service conditions and design requirements,
and durability for a specific application.
including environmental conditions, mechanical properties and
areal density or equivalent measure of neutron absorber con-
3.1.14 systematic sampling, n—a sample selection proce-
tent. Selection of environmental and service conditions that are
dure in which every kth element is selected from the universe
important for neutron absorber material performance and
or population, for example, u, u + k, u+2k, u+3k, etc., where
qualification should take into consideration known failure
u is in the interval 1 to k. E456
modes and industry experience.
3.2 Definitions of Terms Specific to This Standard:
5.1.1 Environmentalconditionstobeconsideredincludebut
3.2.1 designer, n—the organization responsible for the de-
are not limited to water chemistry, water temperature, paired
sign or the license holder for the dry cask storage system or
dissimilar materials, hydrostatic pressure, duration of
transport packaging. The designer is usually the purchaser of
immersion, gamma and fast neutron flux, heat-up rate after
the neutron absorber material, either directly or indirectly
draining, and maximum temperature.
(through a fabrication subcontractor).
5.1.2 For structural applications, specify the mechanical
properties required by the structural analysis. For non-
4. Significance and Use
structural uses of the neutron absorber material, specify me-
4.1 For criticality control of nuclear fuel in dry storage and
chanical properties sufficient to assure material durability
transportation, the most commonly used neutron absorber
under the service conditions for which it is designed.
materials are borated stainless steel alloys, borated aluminum
5.1.3 Specify other design properties, for example, thermal
alloys, and boron carbide aluminum alloy composites. The
conductivity, surface finish, etc., as required for the applica-
boron used in these neutron absorber materials may be natural
tion.
or enriched in the nuclide B. The boron is usually incorpo-
5.1.4 Product or feed material chemistry shall be specified.
rated either as an intermetallic phase (for example,AlB ,TiB
2 2
5.2 NeutronAbsorberMaterialQualification—Qualification
, CrB , etc.) in an aluminum alloy or stainless steel, or as a
shall consist of three components: (1) verify durability for the
stable chemical compound particulate such as boron carbide
intended service as defined in 5.2.5, (2) verify that the physical
(B C), typically in an aluminum MMC or cermet.
characteristics of components meet their design requirements
4.2 While other neutron absorbers continue to be investi-
defined in 5.2.6, and (3) verify that the uniformity of the B
gated, Bhasbeenmostwidelyusedintheseapplications,and
distribution in the neutron absorber material is within accept-
it is the only thermal neutron absorber addressed in this
able bounds as specified by the designer as described in 5.2.6.
standard.
5.2.1 Qualification is needed:
4.3 In service, many neutron absorber materials are inac-
5.2.1.1 When the neutron absorber material has not been
cessible and not amenable to a surveillance program. These
previously qualified,
neutron absorber materials are often expected to perform over
5.2.1.2 When a new supplier is producing a qualified
an extended period.
neutron absorber material, or
4.4 Qualification and acceptance procedures demonstrate 5.2.1.3 When any key process or process control, as defined
that the neutron absorber material has the necessary character- in 5.2.7, is altered for production of a qualified neutron
istics to perform its design functions during the service absorber material.
lifetime.
5.2.2 The key processes and process controls for producing
neutron absorber material for qualification should be the same
4.5 The criticality control function of neutron absorber
as those to be used for commercial production. Differences
materials in dry cask storage systems and transportation
shall be justified per 5.2.7.
packagings is only significant in the presence of a moderator,
5.2.3 Re-qualification for a qualified neutron absorber ma-
terial produced by a new supplier may consist of review of key
processes and process controls to verify that they have been
“Regulations for the Safe Transport of Radioactive Material,” Safety Series
Standards No. TS-R-1, International Atomic Energy Agency, Vienna, Austria. adequately replicated by the new supplier.
C1671−07
5.2.4 If a neutron absorber material can not be qualified neutron streaming and self-shielding is insignificant. The
completely by reference to prior testing with similar neutron attenuationtestsonthecalibrationstandardsandontheproduct
absorber materials for similar design functions and service shall use the same test equipment and configuration.
conditions, complete the qualification by performing testing or (2) Neutron attenuation measurements shall be performed
portions thereof as described in 5.2.5 and 5.2.6. in accordance with written procedures that address, as a
minimum, the following:
5.2.5 Environmental Qualification Tests—For these tests,
verify by visual and dimensional inspection, mechanical (a) The calibration standards used and their validation,
(b) The frequency of calibration as required to account for
testing,neutronattenuationtesting,etc.,asappropriate,thatthe
neutron beam intensity variation, or source decay,
neutron absorber material does not undergo physical changes
(c) Neutron source and beam collimation, if any,
that would render it unable to perform its design functions. (d) Method of interpolation between calibration points, and
(e) Neutron detection instrumentation.
5.2.5.1 Forradiationandthermaltesting,exposetheneutron
(f) If the material used for calibration standards contains
absorber material to the service conditions or equivalent
neutron absorbing or scattering nuclides not present in the
neutron absorber material to be examined, the procedure
accelerated conditions.
shall address the effect of these nuclides on the accuracy
5.2.5.2 Corrosion testing shall consist of exposing test
of the measurements.
specimens of the neutron absorber material to simulate in-
(3) Using a goodness of fit test, determine if the set of
service immersion conditions.
measurement data is normally distributed. For a normal
5.2.5.3 If the neutron absorber material has open porosity,
distribution, calculate the lower tolerance limit, T, for the areal
test it under simulated loading and service conditions using
density or neutron absorber density for each lot, that is, a
bounding pressure, temperature, time, and vacuum.
number T such that at least a proportion, P, of the lot is greater
5.2.6 Mechanical, Absorber Uniformity, and Other Qualifi-
than T with confidence γ. Usually, P ≥ 95 % andγ≥ 95 %.
cation Testing:
Calculate T as follows:
5.2.6.1 Perform tensile tests according to Test Method
T 5 x bar 2 K*s (1)
~ !
B557, B557M, E8,or E21. Perform any other mechanical
where:
testing, for example, fracture toughness testing, bend testing,
etc., in accordance with the appropriate ASTM test method.
T = thelowertolerancelimit,g/cm forarealdensityor
For neutron absorber materials where standardized testing is
g/cm for neutron absorber density,
not appropriate, such as for laminates, develop the mechanical
K = the one-sided tolerance limit factor for a normal
5,
test appropriate for the materials. distribution with probability P and confidence γ,
dimensionless,
NOTE 1—Most neutron absorbers are non-structural and are held in 2 3
x(bar) = the sample average, g/cm or g/cm , and
place during service by structural components. If the absorber material is
2 3
s = the sample standard deviation, g/cm or g/cm .
intended as a structural member, other tests may be necessary to conform
NOTE 2—If the data set is not normally distributed, then a nonparamet-
to a structural code (for example, ASME Boiler and Pressure Vessel
ric lower tolerance limit may be used. In this case, the method must be
Codes). It may also be necessary to consider the long term service
documented.
temperature and the effect of aging on the tensile strength of aluminum
NOTE 3—The user is advised to consider the effect of the statistical
alloy-based absorber materials.
uncertainty in neutron counting, which may contribute to the standard
5.2.6.2 Assess the uniformity of the neutron absorber dis- deviation of the measurements and thus affect the lower tolerance limit. In
neutron attenuation testing, the fractional statistical uncertainty of count-
tribution in the neutron absorber material by measuring either:
3 ing is equal to the square root of the number of counts divided by the
(1) the neutron absorber density (g/cm ) and thickness, or (2)
number of counts.
the areal density (g/cm ) by either: (1) probability sampling or
5.2.6.3 Verify other properties as required by the design, for
(2) systematic samp
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