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SG-100/R2/Appendix H/09-30-05

APPENDIX H

Determination of ASME BPVC Material Properties and Allowables

The materials selected for the fabrication of a packaging designed to transport nuclear

materials are often chosen for their ability to shield and contain the radioactive contents.However, if fissile material is being transported, the materials of construction can also

be used to maintain the spatial distribution and subcriticality within the package. The

materials of construction for the packaging containment system should ensure structural

containment of the hazardous material. These materials of construction, supported by

the material certifications and structural analysis, must be shown by design and testing

to adequately contain the radioactive material.

10 CFR 71.33(a)(5) requires applications to include a description of the proposed

package in sufficient detail to identify the package accurately and provide a sufficient

basis for evaluation of the package. The description must include specific information

regarding the materials of construction, weights, dimensions and fabrication methods.

10 CFR 71.31(c) requires the applicant to include the identification of any established

codes and standards proposed for use in the package design, fabrication, assembly,

testing, maintenance, and use. And in the absence of any codes and standards

requires the applicant to describe and justify the basis and rationale used to formulate

the packages quality assurance program. Although materials of construction are not

specifically mentioned, their selection is an integral part of the design process.

Therefore, the codes and standards that are used to determine the properties for the

materials of construction need to be identified.

As stated above, 10 CFR 71.31(c) provides the applicant the option of describing and

justifying the basis and rationale used to formulate the packages quality assurance

program in the absence of any material codes or standards. However, the current

regulatory practice has been to limit the choice of materials for vital package safety

components to those which have existing codes and/or standards that have been

established by nationally recognized organizations (i.e. ASME and ASTM) or long

standing commercial manufacturers of products (i.e. Parker Seals) used in similar

applications.

The regulatory requirement in combination with the regulatory practice compel the

applicant to use materials whose characteristics and properties are well known and

documented by testing, and verified by operational experience in similar applications.

This ensures that the materials selected have material properties, which serve as a

basis for the various safety analyses that have been extensively tested and proven.

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Any materials proposed for vital package safety components whose material properties

are not described by such codes or standards must be adequately characterized and

well documented. The application should include a characterization of the materials

with respect to the values of their mechanical, thermal and physical properties; the

means by which the quality of the materials is ensured; and any effects that the

fabrication processes may have on the materials.

The material properties are external measures of how the materials behave in the

presence of applied loads and environmental conditions such as internal or external

pressure, dynamic and vibration loads, interactions with fluids, hot and cold

temperatures, and so on. The objective is to use these properties to fully describe how

the packaging materials will react to any combination of the applied loads and

environmental conditions.

ASME BPVC

The ASME BPVC is an internationally recognized pressure vessel code that establishes

requirements for design, material selection, fabrication, examination, and testing of

nuclear and non-nuclear pressure vessels. Consequently, for metal components the

ASME BPVC metallic material requirements have been adopted as the standard for

selection and use of metallic materials for the fabrication of vital packaging safety

components.

Selection of appropriate metallic materials for package design with associated

fabrication and acceptance guidelines is based the applicable ASME BPVC sections.

The materials information is located in Section II[H-2] of the ASME BPVC. The following

is a list of the parts that make up Section II:

Part A, Ferrous Material Specification

Part B, Non-Ferrous Material Specification

Part C, Specifications for Welding, Rods, Electrodes, and Filler Metals

Part D, Properties

Section II, Part D is also divided into Subparts, followed by Appendices. These

Subparts are:

Subpart 1 - Stress Tables

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Subpart 2 - Physical Properties Tables

Subpart 3 - Charts and Tables for Determining Shell Thickness of Components

Under External Pressure

The tables from Section II, Part D, Subpart 1 listed below are used most often whendetermining material properties for NNSA packaging materials:

Tables 1A and 1B cover Sections I and III (Class 2 and 3 material), and Section

VIII, Division 1. These tables contain the maximum allowable stress values (S)

for ferrous (1A) and nonferrous (1B) materials.

Tables 2A and 2B cover Section III, Class 1 material and Section VIII, Division 2.

These tables contain the design stress intensity values (Sm) for ferrous (2A) and

nonferrous material (2B).

Table 3 covers Section III (Class 2 and 3 material) and Section VIII, Divisions 1

and 2. This table contains the maximum allowable stress values (S) for bolting

materials.

Table 4 covers Section III (Class 1 material) and Section VIII, Division 2. This

table contains the design stress intensity values (Sm) for bolting materials.

Table U contains tensile strength values (Su) for ferrous and nonferrous

materials.

Table Y-1 contains yield strength values (Sy) for ferrous and nonferrous

materials.

The tables from Section II, Part D, Subpart 2 listed below are used most often when

determining material properties for NNSA packaging materials:

Table TE-1 for the thermal expansion of ferrous materials.

Table TM-1 for the modulus of elasticity for ferrous materials.

However, it should be noted that Subpart 2 contains thermal expansion and modulus of

elasticity tables for more materials than what is listed in this appendix (e.g., aluminum

alloys, nickel alloys, etc.). Tables TE-1 and TM-1, listed above, are those most often

used when determining material properties for materials used in NNSA packagings.

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Paragraph C.1 of RG 7.6[H-3] specifies that values for material properties, design stress

intensity (stress allowable), and design fatigue curves for Class 1 components should

be in accordance with ASME BPVC rules and specifications. Specifications for the

materials are contained in Parts A and B and the design stress intensities for these

materials are located in Part D. Section II, Part D contains tables of tensile strength,

yield strength, thermal expansion, thermal conductivity, thermal diffusivity, and modulus

of elasticity. However, none of these are specific to any particular ASME BPVC section,

with the exception of Tables U-2 and Y-3, which are specific to Section VIII, Division 3.

Section II is an integral part of the ASME BPVC, as it interacts with all sections of the

Code. Section II, Part D is the focal point for allowable stresses and properties for

those materials permitted in Sections I, III, and VIII (Divisions 1 and 2) construction.

In the event that a material selected is not covered by an ASME specification, the NRC

allows stress intensity limits to be defined in accordance with Article III-2000 of the

ASME BPVC, Section III, Division 1, Appendices.[H-4] These procedures for Class 1components mandate the safety margins that are to be applied to either the yield or the

tensile strength minimum specified in an authoritative material specification. The code

of choice, if the material is not listed in the ASME BPVC, is the collection of

specifications published by the ASTM. The specifications for materials given in Section

II are identical or similar to those of the Specifications published by the ASTM, AWS, or

other recognized national or international organizations.

Material Table Example

There are a few details that must be known before material properties can be found in

Part D. First, the containment boundary materials must be identified. This includes

identifying such information as whether it is ASME or ASTM material, the type or grade,

the product form, and the nominal composition of the material. Next, the operating

temperature and the range of the temperatures over which the material is to be used

must be determined. Also, in order to use the correct table in Part D, Subpart 1, the

section of the Code that is being used must be known so that the component class

(Class 1, 2, or 3) can be determined.

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Component/Material/UNS Number.

The assigned nominal composition for a given type of material must be known

(particularly for ferrous materials) since this determines its location in the various tables

in the Code. The nominal composition only contains the major alloying elements, not

every element present in the material. For example, SA-240, Type 304L is a stainless

steel composed primarily of chromium and nickel. Therefore, its nominal composition is

18Cr-8Ni. Next, the material type or grade should be given (i.e., Type 304, Type 304L,

etc.) and its product form (e.g., plate, forging, welded pipe, seamless pipe, etc.). The

UNS number should also be identified. The alloys used in the ASME BPVC are divided

into 10 groupings of UNS numbers as follows:

AXXXXX Aluminum-base alloys

CXXXXX Copper-base alloys

FXXXXX Cast iron alloys

GXXXXX AISI and SAE carbon and alloy steels

HXXXXX AISI and SAE H-steels

JXXXXX Cast steels

KXXXXX Miscellaneous steel and ferrous alloys

NXXXXX Nickel-base alloys

RXXXXX Special metals and alloys

SXXXXX Heat and corrosion resistant steels

Table H-1 provides an example of the ASME material properties for the materials used

in components of a typical NNSA package containment boundary. Note that all the

materials are heat and corrosion resistant steels (SXXXXX), which is common for NNSA

packages.

Materials other than ASME materials may be identified for package construction. For

example, in Table H-1, the containment boundary pipe is constructed of ASTM material

(A-312). When this is the case, the ASTM specification should be compared with the

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ASME specification located in Part A. If the material is not identical, any exceptions are

listed at the beginning of the ASME specification and should be noted as shown in

Table H-1 (note a). It is also good practice to state the part of the containment

boundary where the material is used.

Temperature

In Table H-1, the normal operating temperature is assumed to be 200 F. The normal

operating temperature is the temperature used in the SARP to bound the normal

conditions. Note this is not the same as the design temperature, which is chosen by the

designer of the package and usually higher than or equal to the normal operating

temperature. The range of temperatures that the components are subjected to in Table

H-1 is conservatively assumed to be 100 F to 600 F. It is important to see how the

various material properties react over a range of temperatures, especially if a chosen

material is not commonly used in transportation packages.

Mechanical Properties

The tables in ASME BPVC Section II, Part D, Subpart 1 are provided to assist the users

determine the materials yield strength, ultimate strength, membrane allowable, elastic

modulus, and coefficient of thermal expansion. There are a few items that should be

noted:

The allowable stress is based on the minimum specified properties at room

temperature and trend curves are based on ASME testing, not actual properties.

When determining the maximum allowable stress values (S) or design stressintensity (Sm), there are times when the same material composition and

specification are listed more than once. When this is the case, look at the

product form (for example, one line number may be for seamless pipe while the

other is for welded pipe), and also look at the size/thickness column. If neither of

these columns narrow the choice to the appropriate line number, then look at the

Applicability and Maximum Temperature Limits column. This column states

whether the material is permitted or not permitted (NP) by ASME BPVC section.

If it is permitted, it gives the maximum temperature of the material per that ASME

BPVC section.

When determining the coefficient of thermal expansion, three coefficients are

given: A, B, and C. Coefficient A is the instantaneous coefficient of thermal

expansion 10-6, Coefficient B is the mean coefficient of thermal expansion 10-6

in going from 70 F to the indicated temperature, and Coefficient C is the linear

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thermal expansion 10-6 in going from 70 F to the indicated temperature. In

most cases, Coefficient B is used in the materials table, as is shown in the

example table (H-1).

Elongation values for ASME materials are located in Part A of ASME BPVC,

Section II -- not Part D.

Table H-1. Example ASME Material Properties for Materials Used in a

NNSA Package Containment Boundary

Material/UNS number/component

Temp.(F)

YieldstrengthSy (ksi)

b

UltimatestrengthSu (ksi)

c

MembraneallowableSm (ksi)

d

Elasticmodulus(10

6psi)

e

Coefficient ofexpansion

(10-6

in/in-F)f

Elongationg

100 25.0 70.0 16.7 28.0 8.6

200 21.4 66.1 16.7 27.6 8.9300 19.2 61.2 16.7 27.0 9.2

400 17.5 58.7 15.8 26.5 9.5

500 16.4 57.5 14.7 25.8 9.7

ASTM A-312,

Type TP304L,18Cr-8Ni, wldpipe, S30403(pipe)

a

600 15.5 56.9 14.0 25.3 9.8

35% (long.)

100 25.0 70.0 16.7 28.0 8.6

200 21.4 66.1 16.7 27.6 8.9

300 19.2 61.2 16.7 27.0 9.2

400 17.5 58.7 15.8 26.5 9.5

500 16.4 57.5 14.7 25.8 9.7

ASME SA-182,Type F304L,18Cr-8Ni,forging, S30403(lid, top flange,bottom) 600 15.5 56.9 14.0 25.3 9.8

30%

100 85.0 130.0 28.3 29.0 8.2

200 83.3 130.0 27.8 28.5 8.5300 82.0 130.0 27.3 27.9 8.8

400 80.8 129.7 26.9 27.3 8.9

500 79.3 127.1 26.4 26.7 9.1

ASME SA-453,Grade 660,Class A or B,25/26Ni-15Cr-2Ti, S66286(screws) 600 77.9 124.8 26.0 26.1 9.2

15%

Notes:

Class 1 materials are usedfor the containment boundary.

a ASME SA-312 is identical with ASTM specification A 312/A 312M-00b, except for H Grade heat treatment in 6.2(Part A).

b ASME BPVC, Section II, Part D, Table 2A (ASME 2001).c ASME BPVC, Section II, Part D, Table U (ASME 2001).

d ASME BPVC, Section II, Part D, Table Y-1 (ASME 2001).e ASME BPVC, Section II, Part D, Table TM-1 (ASME 2001).f ASME BPVC, Section II, Part D, Table TE-1 (group 3, coefficient B for A-312 and SA-182, and group 4, coefficient

B for SA-453) (ASME 2001).g ASME BPVC, Section II, Part A (ASME 2001).

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References

H-1 NRC, Code of Federal Regulations, Title 10, Energy, Part 71, Packaging and

Transportation of Radioactive Material, October 1, 2004.

H-2 ASME, Boiler and Pressure Vessel Code, Section II, New York, New York,2001.

H-3 NRC, Design Criteria for the Structural Analysis of Shipping Cask

Containment Vessels, Regulatory Guide 7.6, Rev. 1, Washington, D.C., 1978.

H-4 ASME, Boiler and Pressure Vessel Code, Section III, Division 1, Appendices,

New York, New York, 2001.

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