Designation: E 2023 – 99

Standard Practice for

Fabrication of Neutron Radiographic Sensitivity Indicators1
This standard is issued under the fixed designation E 2023; 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 (e) indicates an editorial change since the last revision or reapproval.

1. Scope 4.2 Neutron radiography practices are discussed in Practices

1.1 This practice covers the fabrication of Sensitivity Indi- E 748. The neutron radiograph used to determine image quality
cators (SI), which can be used to determine the relative quality using the SI shall meet the requirements of Method E 545.
of radiographic images produced by direct, thermal neutron 5. Significance and Use
radiographic examination.
1.2 The values stated in inch-pound units are regarded to be 5.1 The only truly valid image quality indicator is a material
standard. The SI equivalents given in parentheses in the text are or component, equivalent to the part being neutron radio-
for information only. graphed, with a known standard discontinuity, inclusion, omis-
1.3 This standard does not purport to address all of the sion or flaw (reference standard comparison part). The SI is
safety concerns, if any, associated with its use. It is the designed to substitute for the reference standard, providing
responsibility of the user of this standard to establish appro- qualitative information on hole and gap sensitivity in a single
priate safety and health practices and determine the applica- unit. Fabrication in accordance with this practice is vital for
bility of regulatory limitations prior to use. accurate and consistent measurements.
5.2 This practice shall be followed for the fabrication of all
2. Referenced Documents SIs to be used with Method E 545 to determine image quality
2.1 ASTM Standards: in direct thermal neutron radiography.
E 543 Practice for Evaluating Agencies Performing Nonde- 6. Basis of Application
structive Testing2
E 545 Method for Determining Image Quality in Direct 6.1 Qualification of Nondestructive Agencies—If specified
Thermal Neutron Radiographic Examination2 in the contractual agreement, NDT agencies shall be qualified
E 748 Practices for Thermal Neutron Radiography of Ma- and evaluated as described in Practice E 543. The applicable
terials2 edition of Practice E 543 shall be specified in the contractual
E 1316 Terminology for Nondestructive Examinations2 agreement.
6.2 Procedures and Techniques—The procedures and tech-
3. Terminology niques to be utilized shall be as described in this practice unless
3.1 Definitions—For definitions of terms used in this prac- otherwise specified. Specific techniques may be specified in the
tice, see Terminology E 1316, Section H. contractual agreement.
6.3 Reporting Criteria/Acceptance Criteria—Reporting cri-
4. Summary of Practice teria for the examination results shall be in accordance with
4.1 The Sensitivity Indicator (SI) is used for qualitative Sections 9 and 10 unless otherwise specified. Acceptance
determination of the sensitivity of detail visible on the neutron criteria, for example, reference radiographs, shall be specified
radiograph. It consists of a step wedge containing gaps and in the contractual agreement.
holes of known dimensions. Visual inspection of the image of 6.4 Reexamination of repaired/reworked items is not ad-
this device provides subjective information regarding total dressed in this practice and, if required, shall be specified in the
radiographic sensitivity with respect to the step-block material, contractual document.
as well as optional subjective data, regarding detrimental levels
7. Sensitivity Indicator (SI)
of gamma exposure.
7.1 The Sensitivity Indicator (SI) shall be constructed of
cast acrylic resin, lead (optional), and aluminum. The construc-
tion and dimensions are shown in Fig. 1.
1
This practice is under the jurisdiction of ASTM Committee E-7 on Nonde- 7.2 The optional lead step in the SI may be replaced with a
structive Testing and is the direct responsibility of Subcommittee E07.05 on
Radiology (Neutron) Method.
blank, cast acrylic resin step. The lead provides a visual
Current edition approved June 10, 1999. Published August 1999. indication of beam gamma content; however, the lead image is
2
Annual Book of ASTM Standards, Vol 03.03. not used for any of the SI calculations of Method E 545.

Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.

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 E 2023 – 99

Material — Methylmethacrylate
Shim Thickness Hole Diameter
A 0.005 0.005
B 0.010 0.010
C 0.020 0.020
D 0.010 0.010

NOTE 1—All dimensions are in inches.

NOTE 2—The lead step may be replaced with a methylmethacrylate strip with the D shim eliminated.
FIG. 1 Sensitivity Indicator

7.3 The acrylic resin shall be methylmethacrylate. 6.5-in. (165-mm) long. The near edge of channel A should be
7.4 All dimensional tolerances are as noted on the figures. 0.450-in. (11.4-mm) from edge A (see Fig. 3).
7.5 Aluminum shims and strips shall be 99.9 % pure el- 8.1.3 Mill the B Channel, adjacent to the A channel,
emental material. 0.125-in. (3.18-mm) wide 3 0.010-in. (0.254-mm) deep 3
7.6 The SI may be encased in a 6061 aluminum dust cover, 6.5-in. (165-mm) long. The near edge of channel B should be
0.012-in. (0.305-mm) thick. 0.325-in. (8.26-mm) from edge A (see Fig. 3).
7.7 When used, the optional lead shim shall be at least 8.1.4 Mill the C Channel, adjacent to the B channel,
99.9 % pure elemental material. 0.125-in. (3.18-mm) wide 3 0.020-in. (0.508-mm) deep 3
6.5-in. (165-mm) long. The near edge of channel C should be
8. Fabrication3 0.200 in. (5.08 mm) from edge A (see Fig. 3).
8.1 Components: 8.1.5 Optional—Mill the D channel adjacent to the C
8.1.1 Mill a Channel, 0.850-in. (21.6-mm) wide 3 6.5-in. channel, 0.125-in. (3.18-mm) wide 3 0.010-in. (0.254-mm)
(165-mm) long from an aluminum block, 1-in. (25.4-mm) wide deep 3 6.5-in. (165-mm) long. The near edge of channel D
3 at least 0.303-in. (7.70-mm) high 3 6.5-in. (165-mm) long. should be 0.075-in. (1.90-mm) from edge A.
The channel should begin 0.075-in. (1.90-mm) from edge A NOTE 1—The D channel is not required and shall not be milled if the
and leave 0.103-in. (2.62-cm) aluminum in the bottom of the lead shim is not to be used.
channel (see Fig. 2).
8.1.2 Mill the A Channel (see Fig. 1), within this channel, 8.1.6 Prepare five methylmethacrylate strips, 0.060-in.
0.125-in. (3.18-mm) wide3 0.005-in. (0.127-mm) deep 3 (1.52-mm) thick 3 at least 0.200-in. (5.08-mm) wide 3 6.5-in.
(165-mm) long. These strips will be used in 8.2.11.
8.1.7 Prepare four methylmethacrylate strips, 0.125-in.
3
The instructions in Section 8 assume the simultaneous fabrication of five units (3.18-mm) thick 3 at least 0.200-in. (5.08-mm) wide 3 6.5-in.
for practical reasons. Units may be fabricated singly, if desired. (165-mm) long. One of the methylmethacrylate strips may be

2
 E 2023 – 99

NOTE 1—Unless otherwise specified, use the following:

Dimensions are in inches.
Tolerances on machined dimensions: .XX = 6 .01 .XXX = 6 .002.
FIG. 2 Main Channel in Aluminum Block

replaced with an optional lead strip of the same dimensions. To verify that the various shims have the proper holes drilled
These strips will be used in 8.2.5. into them, a certified hole measurement report is required.
8.1.8 Prepare one each strip from aluminum shim stock, at 8.1.11 To keep the SI intact during use, it is highly recom-
least 0.200-in. (5.08-mm) wide 3 6.5-in. (165-mm) long, with mended that a dust cover be kept on the unit. One dust cover
the following thickness: for each SI may be prepared from aluminum shim stock,
0.0005 in. (0.0127 mm) 0.012-in. (0.305-mm) thick 3 1.50-in.2 (38.1-mm2) by cutting
0.0010 in. (0.0254 mm) out a 0.250-in.2 (6.35-mm2) from each corner and folding the
0.0020 in. (0.0508 mm)
0.0030 in. (0.0762 mm) aluminum to form a cover, 1-in.2 (25.4-mm2) 3 0.250-in.
0.0040 in. (0.102 mm) (6.35-mm) high (see Fig. 1).
0.0050 in. (0.127 mm)
0.0100 in. (0.254 mm)
8.2 Assembly:
8.2.1 Insert Shim C into the C channel milled in 8.1.4 (see
8.1.9 Prepare one each methylmethacrylate strip to fit Fig. 5).
snugly in the 0.125-in. (3.18-mm) wide 3 6.5-in. (165-mm) 8.2.2 Insert Shim B into the adjacent B channel milled in
long with the following thickness: 8.1.3 (see Fig. 5).
0.0050 in. (0.127 mm) (Shim A)
0.0100 in. (0.254 mm) (Shim B)
8.2.3 Insert Shim A into the adjacent A channel milled in
0.0200 in. (0.508 mm) (Shim C) 8.1.2 (see Fig. 5).
0.0100 in. (0.254 mm) (Shim D) (If used, this strip is to be fab- 8.2.4 If the D channel was milled in 8.1.5, insert the lead
ricated from lead stock (see Fig. 4). These strips will become
Shim A through Shim D in 8.1.10.) shim (see Fig. 5).
8.2.5 Insert a 0.125-in. (3.18-mm) methylmethacrylate strip
8.1.10 Drill four holes in the shims from 8.1.9, starting (previously prepared in 8.1.7) into the channel so that the
0.218 in. (5.54 mm) from one end and centering the other three second strip is positioned over Shim C. Over Channel D, insert
holes 0.215 in. (5.46 mm) from the first hole. Repeat the either the optional lead strip or a 0.125-in. (3.18-mm) methyl-
process along the rest of the 6.5-in. (165-mm) length (see Fig. methacrylate strip (see Fig. 6).
4). The diameter of the holes are as follows: 8.2.6 Insert the 0.010-in. (0.254-mm) thick aluminum strip
Shim A 0.005-in. (0.127-mm) diameter next to the methylmethacrylate strip between the B and C
Shim B 0.010-in. (0.254-mm) diameter
Shim C 0.020-in. (0.508-mm) diameter
channels (see Fig. 6).
Shim D 0.010-in. (0.254-mm) diameter, if optional Shim D is to 8.2.7 Insert another 0.125-in. (3.18-mm) methylmethacry-
be used. late strip next to the aluminum strip (see Fig. 6).

3
 E 2023 – 99

NOTE 1—Unless otherwise specified, use the following:

Dimensions are in inches.
Tolerances on machined dimensions: .XX = 6 .01 .XXX = 6 .002.
FIG. 3 Channels A Through D in Main Channel

Shim Thickness Hole Diameter

A 0.0050 0.0050
B 0.0100 0.0100
C 0.0200 0.0200
D 0.0100 0.0100
FIG. 4 Shims

8.2.8 Insert the 0.005-in. (0.127-mm) thick aluminum strip 8.2.11 Insert a 0.060-in. (1.52-mm) thick methylmethacry-
(see Fig. 6). late strip next to the previously inserted aluminum strip (see
8.2.9 Insert the last 0.125-in. (3.18-mm) methylmethacry- Fig. 6).
late strip next to the previously inserted aluminum strip (see 8.2.12 Repeat the steps described in 8.2.10 and 8.2.11,
Fig. 6). alternating increasing aluminum strip thickness with 0.060-in.
8.2.10 Insert the 0.0005-in. (0.0127-mm) thick aluminum (1.52-mm) thick methylmethacrylate strips (see Fig. 6), that is:
strip next to the previously inserted methylmethacrylate strip
(see Fig. 6).

4
 E 2023 – 99

NOTE 1—See Fig. 4.

FIG. 5 Shims in Channels

Unless otherwise specified, use the following:

Dimensions are in inches.
Tolerances on machined dimensions: .XX = 6 .01 .XXX = 6 .002.
FIG. 6 Strips in Main Channel

0.001-in. (0.0254-mm) thick aluminum strip 8.3 Fabrication:

0.060-in. (1.52-mm) thick methylmethacrylate strip
0.002-in. (0.0508-mm) thick aluminum strip
8.3.1 Mill off a 1.0-in. (25.4-mm) long section of the
0.060-in. (1.52-mm) thick methylmethacrylate strip stacked channel from the 6.5-in. (165-mm) length.
0.003-in. (0.0762-mm) thick aluminum strip
0.060-in. (1.52-mm) thick methylmethacrylate strip
8.3.2 Mill the top surface of the sectioned unit to a height of
0.004-in. (0.102-mm) thick aluminum strip 0.303 in. (7.70 mm). This height is equivalent to the first step
0.060-in. (1.52-mm) thick methylmethacrylate strip of 0.200 in. (5.08 mm) of methylmethacrylate (see Fig. 7).
8.2.13 Cut and insert aluminum shims sized as required for 8.3.3 Mill a 0.215-in. (5.46-mm) wide channel, 0.230-in.
a tight fit between the last 0.060-in. (1.52-mm) methyl- (5.84-mm) from Edge B (as shown in Fig. 7) across the full
methacrylate strip and the wall of the channel to wedge all the width of the stacked assembly, including the aluminum walls.
strips in place (this step is important for later machining of the The bottom of the channel should be 0.203 in. (5.16 mm) from
unit) (see Fig. 6). the bottom of the block.

5
 E 2023 – 99

Unless otherwise specified, use the following:

Dimensions are in in.
Tolerances on machined dimensions: .XX = 6 .01 .XXX = 6 .002.
FIG. 7 First Milled Step

8.3.4 Mill another 0.215-in. (5.46-mm) wide channel, 8.3.6 Mill the final 0.215-in. (5.46-mm) wide channel,
0.445-in. (11.30-mm) from Edge B (as shown in Fig. 8) across 0.660-in. (16.76-mm) from Edge B, including the aluminum
the full width of the stacked assembly, including the aluminum walls. The bottom of the channel should be 0.128 in. (3.25 mm)
walls. The bottom of the channel should be 0.153 in. (3.89 mm) from the bottom of the block (see Fig. 9).
from the bottom of the block. 8.3.7 Machine a base in the completed unit by cutting 0.015
8.3.5 Finish milling all stock between the aluminum walls in. (0.381 mm) from all four sides. The machining should leave
from the last channel to Surface C to a height of 0.153 in. (3.89 a 0.080-in. (2.03-mm) thick base (see Fig. 9).
mm) from the bottom of the block, as shown in Fig. 7. Do not 8.3.8 The SI is complete and should look identical to the SI
remove material from the aluminum walls. After completion, shown in Fig. 1.
the block should look as shown in Fig. 8. 8.3.9 Slip-fit the dust cover from 8.1.11. Do not use glue.

Unless otherwise specified, use the following:

Dimensions are in inches.
Tolerances on machined dimensions: .XX = 6 .01 .XXX = 6 .002.
FIG. 8 Second Milled Step

6
 E 2023 – 99

Unless otherwise specified, use the following:

Dimensions are in inches.
Tolerances on machined dimensions: .XX = 6 .01 .XXX = 6 .002.
FIG. 9 Finished Block

9. Certification match those in the reference standard SI’s image, the unit(s)
9.1 Upon request of the purchaser by contract or purchase are acceptable and can be certified.
order, any fabricator of the SI described in this practice shall 9.4 The comparison thermal neutron radiograph of the
provide materials certification. To verify the details of con- assembled SI with the reference standard SI shall meet quality
struction, a measurement certification of individual compo- level Category I, specified in the latest edition of Method
nents and assembly to verify correct location and sizes and a E 545.
comparison thermal neutron radiograph of the assembled SI 9.5 Any SI certified under Method E 545–81, –86, or –91 is
with that of a reference standard SI (preferably on a single assumed to be a reference SI, unless there is known to be a
neutron radiograph) shall be provided. disqualifying deficiency.
9.2 All dimensions should be measured with a micrometer
or an optical comparator to determine the SI dimensions.
10. Records
9.3 The comparison thermal neutron radiograph of the
assembled SI, along with a reference standard SI, shall show 10.1 Complete records of the fabrication details shall be
the following: maintained by the manufacturing facility for three years or as
9.3.1 All shims and strips are in place and aluminum strips specified in the basis of purchase.
are vertical (no blurred edges).
9.3.2 A minimum of six or seven holes should be visible, 11. Keywords
identical to those in the reference SI.
9.3.3 Using a magnifier with a calibrated scale, measure the 11.1 direct method; image quality indicator; neutron radi-
size of the gaps and visible holes. If the measured dimensions ography; sensitivity indicator (SI)

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