ASTM E2059-06(2010)

Standard Practice for Application and Analysis of Nuclear Research Emulsions for Fast Neutron Dosimetry

SIGNIFICANCE AND USE
Integral Mode Dosimetry—As shown in 3.2, two different integral relationships can be established using proton-recoil emulsion data. These two integral reactions can be obtained with roughly an order of magnitude reduction in scanning effort. Consequently this integral mode is an important complementary alternative to the customary differential mode of NRE spectrometry. The integral mode can be applied over extended spatial regions, for example, perhaps up to as many as ten in-situ locations can be covered for the same scanning effort that is expended for a single differential measurement. Hence the integral mode is especially advantageous for dosimetry applications which require extensive spatial mapping, such as exist in Light Water Reactor-Pressure Vessel (LWR-PV) benchmark fields (see Test Method E1005). In low power benchmark fields, NRE can be used as integral dosimeters in a manner similar to RM, solid state track recorders (SSTR) and helium accumulation monitors (HAFM) neutron dosimeters (see Test Methods E854 and E910). In addition to spatial mapping advantages of these other dosimetry methods, NRE offer fine spatial resolution and can therefore be used in-situ for fine structure measurements. In integral mode scanning, both absolute reaction rates, that is I(ET) and J(Emin), are determined simultaneously. Separate software codes need to be used to permit operation of a computer based interactive system in the integral mode (see Section 9). It should be noted that the integrals I(ET) and J(Emin) possess different units, namely proton-recoil tracks/MeV per hydrogen atom and proton-recoil tracks per hydrogen atom, respectively.
SCOPE
1.1 Nuclear Research Emulsions (NRE) have a long and illustrious history of applications in the physical sciences, earth sciences and biological sciences (1,2) . In the physical sciences, NRE experiments have led to many fundamental discoveries in such diverse disciplines as nuclear physics, cosmic ray physics and high energy physics. In the applied physical sciences, NRE have been used in neutron physics experiments in both fission and fusion reactor environments (3-6). Numerous NRE neutron experiments can be found in other applied disciplines, such as nuclear engineering, environmental monitoring and health physics. Given the breadth of NRE applications, there exist many textbooks and handbooks that provide considerable detail on the techniques used in the NRE method. As a consequence, this practice will be restricted to the application of the NRE method for neutron measurements in reactor physics and nuclear engineering with particular emphasis on neutron dosimetry in benchmark fields (see Matrix E706).
1.2 NRE are passive detectors and provide time integrated reaction rates. As a consequence, NRE provide fluence measurements without the need for time-dependent corrections, such as arise with radiometric (RM) dosimeters (see Test Method E1005). NRE provide permanent records, so that optical microscopy observations can be carried out anytime after exposure. If necessary, NRE measurements can be repeated at any time to examine questionable data or to obtain refined results.
1.3 Since NRE measurements are conducted with optical microscopes, high spatial resolution is afforded for fine structure experiments. The attribute of high spatial resolution can also be used to determine information on the angular anisotropy of the in-situ neutron field (4,5,7). It is not possible for active detectors to provide such data because of in-situ perturbations and finite-size effects (see Section 11).
1.4 The existence of hydrogen as a major constituent of NRE affords neutron detection through neutron scattering on hydrogen, that is, the well known (n,p) reaction. NRE measurements in low power reactor environments have been predominantly based on this (n,p) reaction. NRE have also been used to measure the  6Li (n,t)  4He and the  10B (n,α)  7Li reactions by including...

General Information

• Status: Historical
• Publication Date: 30-Sep-2010
• ICS: 17.240 - Radiation measurements
• Technical Committee: E10 - Nuclear Technology and Applications
• Drafting Committee: E10.05 - Nuclear Radiation Metrology

Relations

• Replaces: ASTM E2059-06 - Standard Practice for Application and Analysis of Nuclear Research Emulsions for Fast Neutron Dosimetry
• Effective Date: 01-Oct-2010
• Replaced By: ASTM E2059-15 - Standard Practice for Application and Analysis of Nuclear Research Emulsions for Fast Neutron Dosimetry
• Effective Date: 01-Oct-2015

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: E2059 − 06(Reapproved 2010)
Standard Practice for
Application and Analysis of Nuclear Research Emulsions for
Fast Neutron Dosimetry
This standard is issued under the fixed designation E2059; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope ropy of the in-situ neutron field (4,5,7). It is not possible for
active detectors to provide such data because of in-situ
1.1 Nuclear Research Emulsions (NRE) have a long and
perturbations and finite-size effects (see Section 11).
illustrioushistoryofapplicationsinthephysicalsciences,earth
sciences and biological sciences (1,2) . In the physical
1.4 The existence of hydrogen as a major constituent of
sciences, NRE experiments have led to many fundamental NRE affords neutron detection through neutron scattering on
discoveries in such diverse disciplines as nuclear physics,
hydrogen, that is, the well known (n,p) reaction. NRE mea-
cosmic ray physics and high energy physics. In the applied surements in low power reactor environments have been
physical sciences, NRE have been used in neutron physics
predominantly based on this (n,p) reaction. NRE have also
6 4 10 7
experiments in both fission and fusion reactor environments been used to measure the Li (n,t) He and the B(n,α) Li
6 10
(3-6). Numerous NRE neutron experiments can be found in
reactions by including Li and B in glass specks near the
otherapplieddisciplines,suchasnuclearengineering,environ- mid-plane of the NRE (8,9). Use of these two reactions does
mental monitoring and health physics. Given the breadth of
not provide the general advantages of the (n,p) reaction for
NRE applications, there exist many textbooks and handbooks neutron dosimetry in low power reactor environments (see
that provide considerable detail on the techniques used in the
Section4).Asaconsequence,thisstandardwillberestrictedto
NREmethod.Asaconsequence,thispracticewillberestricted theuseofthe(n,p)reactionforneutrondosimetryinlowpower
to the application of the NRE method for neutron measure-
reactor environments.
ments in reactor physics and nuclear engineering with particu-
1.5 Limitations—The NRE method possesses three major
lar emphasis on neutron dosimetry in benchmark fields (see
limitations for applicability in low power reactor environ-
Matrix E706).
ments.
1.2 NRE are passive detectors and provide time integrated
1.5.1 Gamma-Ray Sensitivity—Gamma-rays create a sig-
reaction rates. As a consequence, NRE provide fluence mea-
nificantlimitationforNREmeasurements.Aboveagamma-ray
surements without the need for time-dependent corrections,
exposure of approximately 3R, NRE can become fogged by
such as arise with radiometric (RM) dosimeters (see Test
gamma-ray induced electron events. At this level of gamma-
Method E1005). NRE provide permanent records, so that
ray exposure, neutron induced proton-recoil tracks can no
optical microscopy observations can be carried out anytime
longer be accurately measured. As a consequence, NRE
after exposure. If necessary, NRE measurements can be re-
experiments are limited to low power environments such as
peated at any time to examine questionable data or to obtain
found in critical assemblies and benchmark fields. Moreover,
refined results.
applications are only possible in environments where the
buildup of radioactivity, for example, fission products, is
1.3 Since NRE measurements are conducted with optical
limited.
microscopes, high spatial resolution is afforded for fine struc-
1.5.2 Low Energy Limit—In the measurement of track
ture experiments. The attribute of high spatial resolution can
length for proton recoil events, track length decreases as
also be used to determine information on the angular anisot-
proton-recoil energy decreases. Proton-recoil track length be-
low approximately 3µ in NRE can not be adequately measured
This practice is under the jurisdiction of ASTM Committee E10 on Nuclear
with optical microscopy techniques. As proton-recoil track
Technology and Applications, and is the direct responsibility of Subcommittee
length decreases below approximately 3µ, it becomes very
E10.05 on Nuclear Radiation Metrology.
Current edition approved Oct. 1, 2010. Published November 2010. Originally
difficult to measure track length accurately. This 3µ track
approved in 2000. Last previous edition approved in 2006 as E2059-06. DOI:
length limit corresponds to a low energy limit of applicability
10.1520/E2059-10.
2 in the range of approximately 0.3 to 0.4 MeV for neutron
The boldface numbers in parentheses refer to the list of references at the end of
induced proton-recoil measurements in NRE.
the text.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E2059 − 06 (2010)
1.5.3 High-Energy Limits—As a consequence of finite-size ment Methods in Reactor Surveillance, E 706 (IIA)
limitations, fast-neutron spectrometry measurements are lim- E1005Test Method for Application and Analysis of Radio-
ited to ≤15 MeV. The limit for in-situ spectrometry in reactor metric Monitors for Reactor Vessel Surveillance, E 706
environments is ≤8MeV. (IIIA)
1.5.4 Track Density Limit—The ability to measure proton
recoiltracklengthwithopticalmicroscopytechniquesdepends 3. Alternate Modes of NRE Neutron Measurements
on track density. Above a certain track density, a maze or
3.1 Neutron Spectrum Measurements—The neutron energy
labyrinth of tracks is created, which precludes the use of
range of interest in reactors environments covers approxi-
optical microscopy techniques. For manual scanning, this
4 2 mately nine orders of magnitude, extending from thermal
limitation arises above approximately 10 tracks/cm , whereas
energies up to approximately 20 MeV. No single high-
interactive computer based scanning systems can extend this
5 2 resolution method of neutron spectrometry exists that can
limit up to approximately 10 tracks/cm . These limits corre-
completely cover this energy range of interest (12). Work with
6 7 −2
spond to neutron fluences of 10 −10 cm , respectively.
proton-recoil proportional counters has not been extended
1.6 Neutron Spectrometry (Differential Measurements)—For
beyondafewMeV,duetotheescapeofmoreenergeticprotons
differential neutron spectrometry measurements in low power
from the finite sensitive volume of the counter. In fact,
reactor environments, NRE experiments can be conducted in
correction of in-situ proportional counters for such finite-size
two different modes. In the more general mode, NRE are
effects can be non-negligible above 0.5 MeV (13). Finite-size
irradiated in-situ in the low power reactor environment. This
effects are much more manageable in NRE because of the
mode of NRE experiments is called the 4π mode, since the
reduced range of recoil protons. As a consequence, NRE fast
in-situ irradiation creates tracks in all directions (see 3.1.1). In
neutron spectrometry has been applied at energies up to 15
special circumstances, where the direction of the neutron flux
MeV (3). For in-situ spectrometry in reactor environments,
is known, NRE are oriented parallel to the direction of the
NREmeasurementsupto8.0MeVarepossiblewithverysmall
neutron flux. In this orientation, one edge of the NRE faces the
finite-size corrections (14-16).
incident neutron flux, so that this measurement mode is called
3.1.1 4π Mode—It has been shown (3-6) that a neutron
the end-on mode. Scanning of proton-recoil tracks is different
fluence-spectrumcanbededucedfromtheintegralrelationship
for these two different modes. Subsequent data analysis is also
` σ E Φ E
~ ! ~ !
np
different for these two modes (see 3.1.1 and 3.1.2).
M E 5 n V dE (1)
~ ! *
p
E
E
1.7 Neutron Dosimetry (Integral Measurements)—NREalso
where:
afford integral neutron dosimetry through use of the (n,p)
Φ(E) = neutron fluence in n/(cm –MeV),
reaction in low power reactor environments. Two different
σ (E) = neutron-proton scattering cross section (cm)at
np
types of (n,p) integral mode dosimetry reactions are possible,
neutron energy, E,
namely the I-integral and the J-integral (10,11). Proton-recoil
E = neutron or proton energy (MeV),
track scanning for these integral reactions is conducted in a
n = atomic hydrogen density in the NRE (atoms/cm ),
p
differentmodethanscanningfordifferentialneutronspectrom-
V = volume of NRE scanned (cm ), and
etry (see 3.2). Integral mode data analysis is also different than
M (E) = proton spectrum (protons/MeV) observed in the
the analysis required for differential neutron spectrometry (see
NRE volume V at energy E.
3.2). This practice will emphasize NRE (n,p) integral neutron
dosimetry, because of the utility and advantages of integral The neutron fluence can be derived from Eq 1 and takes the
mode measurements in low power benchmark fields. form:
2E dM
2. Referenced Documents Φ E 5 (2)
~ !
σ E n V dE
~ !
np p
2.1 ASTM Standards:
Eq 2 reveals that the neutron fluence spectrum at energy E
E706MasterMatrixforLight-WaterReactorPressureVessel
depends upon the slope of the proton spectrum at energy E.As
Surveillance Standards, E 706(0) (Withdrawn 2011)
a consequence, approximately 10 tracks must be measured to
E854Test Method for Application and Analysis of Solid
give statistical accuracies of the order of 10% in the neutron
State Track Recorder (SSTR) Monitors for Reactor
fluence spectrum (with a corresponding energy resolution of
Surveillance, E706(IIIB)
the order of 10%). It must be emphasized that spectral
E910Test Method for Application and Analysis of Helium
measurements determined with NRE in the 4π mode are
Accumulation Fluence Monitors for Reactor Vessel
absolute.
Surveillance, E706 (IIIC)
3.1.2 End-On Mode—Differential neutron spectrometry
E944Guide for Application of Neutron Spectrum Adjust-
with NRE is considerably simplified when the direction of
neutron incidence is known, such as for irradiations in colli-
mated or unidirectional neutron beams. In such exposures, the
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
kinematicsof(n,p)scatteringcanbeusedtodetermineneutron
Standards volume information, refer to the standard’s Document Summary page on
energy. Observation of proton-recoil direction and proton-
the ASTM website.
recoil track length provide the angle of proton scattering
The last approved version of this historical standard is referenced on
www.astm.org. relative to the incident neutron direction, θ, and the proton
E2059 − 06 (2010)
energy, E , respectively. In terms of these observations, the Here I(E ) possesses units of proton-recoil tracks/MeV per
p T
neutron energy, E , is simply: hydrogen atom. Clearly I(E ) is a function of the lower proton
n T
energy cut-off used for analyzing the emulsion data. Using Eq
E
p
E 5 (3)
4 in Eq 1, one finds the integral relation:
n 2
cos θ
M E
~ !
T
In collimated or unidirectional neutron irradiations, the
I~E ! 5 (5)
T
n V
p
emulsion is exposed end-on as depicted in Fig. 1. The end-on
mode can be used to advantage in media where neutron
I(E ) is evaluated by using a least squares fit of the scanning
T
scattering is negligible for two types of benchmark field
data in the neighborhood of E=E . Alternatively, since:
T
experiments, namely:
dR~E!
3.1.2.1 Benchmark field validation of the NRE method or M E 5 M R (6)
~ ! ~ !
T T
dE
characterization of point neutron sources, for example, the
standard Cf neutron field at the National Institute of Stan-
where: R(E) is the proton-recoil range at energy E in the
dards and Technology (NIST) (17).
NRE and dR/dE is known from the proton range-energy
3.1.2.2 Measurement of leakage neutron spectra at suffi-
relation for the NRE. One need only determine M(R)inthe
ciently large distances from the neutron source, for example,
neighborhood ofR=R . Here M(R) is the number of
T
neutron spectrum measurements at the Little Boy Replica
proton-recoil tracks/micron observed in the NRE.
(LBR) benchmark field (18).
Consequently, scanning efforts can be concentrated in the
neighborhood of R=R in order to determine I(E ). In this
T T
3.2 Integral Mode—It is possible to use emulsion data to
manner, the accuracy attained in I(E ) is comparable to the
T
obtain both differential and integral spectral information.
accuracy of the differential determination ofΦ(E), as based on
Emulsion work is customarily carried out in the differential
Eq 2, but with a significantly reduced scanning effort.
mode (3-6). In contrast, NRE work in the integral mode is a
3.2.2 The J Integral Relation—The second integral relation
more recent concept and, therefore, a fuller explanation of this
canbeobtainedbyintegrationoftheobservedprotonspectrum
approach is included below. In this integral mode, NRE
M(E ). From Eq 1:
provide absolute integral reaction rates, which can be used in T
spectral adjustment codes. Before these recent efforts, such
` ` ` σ E
~ !
M E dE 5 n V dE Φ E dE (7)
* ~ ! * * ~ !
T T p T
codes have not utilized integral reaction rates based on NRE.
E E E
E
min min T
The significance of NRE integral reaction rates stems from the
where: E is the lower proton energy cut-off used in
underlying response, which is based on the elastic scattering min
analyzing the NRE data. Introducing into Eq 7 the definitions:
cross section of hydrogen. This σ (E) cross section is
np
`
universally accepted as a standard cross section and is known
µ~E ! 5 M~E !dE (8)
*
min T T
E
to an accuracy of approximately 1%. min
3.2.1 The I Integral Relation—The first integral relationship
and:
follows directly from Eq 1.The integral in Eq 1 can be defined
` ` σ E
~ !
as:
J~E ! 5 * dE * Φ~E! (9)
min T
E E
E
min T
` σ ~E!
I E 5 Φ E dE (4)
~ ! * ~ !
T
E E has:
T
FIG. 1 Geometrical Configuration for End-On Irradiation of NRE
E2059 − 06 (2010)
µ E non-existence of NRE data. NRE integral reaction rates pro-
~ !
min
J~E ! 5 (10)
min
n V vide unique benchmark data for use in least squares spectral
p
adjustment codes. The unique significance of NRE integral
Hence, the second integral relation, namely Eq 10, can be
data arises from a number of attributes, which are described
expressed in a form analogous to the first integral relation,
separatelybelow.Thus,inclusionofNREintegralreactionrate
namely Eq 5. Here µ(E ) is the integral number of proton-
min
data in the spectral adjustment calculations can result in a
recoiltracksperhydrogenatomobservedaboveanener
...