ASTM E910-07(2013)
(Test Method)Standard Test Method for Application and Analysis of Helium Accumulation Fluence Monitors for Reactor Vessel Surveillance, E706 (IIIC)
Standard Test Method for Application and Analysis of Helium Accumulation Fluence Monitors for Reactor Vessel Surveillance, E706 (IIIC)
SIGNIFICANCE AND USE
5.1 The HAFM test method is one of several available passive neutron dosimetry techniques (see, for example, Methods E854 and E1005). This test method can be used in combination with other dosimetry methods, or, if sufficient data are available from different HAFM sensor materials, as an alternative dosimetry test method. The HAFM method yields a direct measurement of total helium production in an irradiated sample. Absolute neutron fluence can then be inferred from this, assuming the appropriate spectrum integrated total helium production cross section. Alternatively, a calibration of the composite neutron detection efficiency for the HAFM method may be obtained by exposure in a benchmark neutron field where the fluence and spectrum averaged cross section are both known (see Matrix E706 IIE).
5.2 HAFMs have the advantage of producing an end product, helium, which is stable, making the HAFM method very attractive for both short-term and long-term fluence measurements without requiring time-dependent corrections for decay. HAFMs are therefore ideal passive, time-integrating fluence monitors. Additionally, the burnout of the daughter product, helium, is negligible.
5.2.1 Many of the HAFM materials can be irradiated in the form of unencapsulated wire segments (see 1.1.2). These segments can easily be fabricated by cutting from a standard inventoried material lot. The advantage is that encapsulation, with its associated costs, is not necessary. In several cases, unencapsulated wires such as Fe, Ni, Al/Co, and Cu, which are already included in the standard radiometric (RM) dosimetry sets (Table 1) can be used for both radiometric and helium accumulation dosimetry. After radiometric counting, the samples are later vaporized for helium measurement.TABLE 1 Neutron Characteristics of Candidate HAFM Materials for Reactor Vessel Surveillance
HAFM Sensor Material
Principal Helium Producing Reaction
Thermal Neutron Cross Section, (b)
Fission Neutron Spectrum...
SCOPE
1.1 This test method describes the concept and use of helium accumulation for neutron fluence dosimetry for reactor vessel surveillance. Although this test method is directed toward applications in vessel surveillance, the concepts and techniques are equally applicable to the general field of neutron dosimetry. The various applications of this test method for reactor vessel surveillance are as follows:
1.1.1 Helium accumulation fluence monitor (HAFM) capsules,
1.1.2 Unencapsulated, or cadmium or gadolinium covered, radiometric monitors (RM) and HAFM wires for helium analysis,
1.1.3 Charpy test block samples for helium accumulation, and
1.1.4 Reactor vessel (RV) wall samples for helium accumulation.
1.2 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 and health practices and determine the applicability of regulatory limitations prior to use.
General Information
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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: E910 − 07 (Reapproved 2013)
Standard Test Method for
Application and Analysis of Helium Accumulation Fluence
Monitors for Reactor Vessel Surveillance, E706 (IIIC)
This standard is issued under the fixed designation E910; 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 Plutonium Fuel (Mass Spectrometric Method) (With-
drawn 2001)
1.1 This test method describes the concept and use of
E261Practice for Determining Neutron Fluence, Fluence
helium accumulation for neutron fluence dosimetry for reactor
Rate, and Spectra by Radioactivation Techniques
vessel surveillance. Although this test method is directed
E482Guide for Application of Neutron Transport Methods
toward applications in vessel surveillance, the concepts and
for Reactor Vessel Surveillance, E706 (IID)
techniquesareequallyapplicabletothegeneralfieldofneutron
E706MasterMatrixforLight-WaterReactorPressureVessel
dosimetry. The various applications of this test method for
Surveillance Standards, E 706(0) (Withdrawn 2011)
reactor vessel surveillance are as follows:
E844Guide for Sensor Set Design and Irradiation for
1.1.1 Helium accumulation fluence monitor (HAFM)
Reactor Surveillance, E 706 (IIC)
capsules,
E853PracticeforAnalysisandInterpretationofLight-Water
1.1.2 Unencapsulated, or cadmium or gadolinium covered,
Reactor Surveillance Results
radiometric monitors (RM) and HAFM wires for helium
E854Test Method for Application and Analysis of Solid
analysis,
State Track Recorder (SSTR) Monitors for Reactor
1.1.3 Charpy test block samples for helium accumulation,
Surveillance, E706(IIIB)
and
E900Guide for Predicting Radiation-Induced Transition
1.1.4 Reactor vessel (RV) wall samples for helium accumu- Temperature Shift in ReactorVessel Materials, E706 (IIF)
lation. E944Guide for Application of Neutron Spectrum Adjust-
ment Methods in Reactor Surveillance, E 706 (IIA)
1.2 This standard does not purport to address all of the
E1005Test Method for Application and Analysis of Radio-
safety concerns, if any, associated with its use. It is the
metric Monitors for Reactor Vessel Surveillance, E 706
responsibility of the user of this standard to establish appro-
(IIIA)
priate safety and health practices and determine the applica-
E1018Guide for Application of ASTM Evaluated Cross
bility of regulatory limitations prior to use.
Section Data File, Matrix E706 (IIB)
2. Referenced Documents
3. Terminology
2.1 ASTM Standards:
3.1 Definitions—For definition of terms used in this test
C859Terminology Relating to Nuclear Materials
method, refer to Terminology C859 and E170. For terms not
E170Terminology Relating to Radiation Measurements and
defined therein, reference may be made to other published
Dosimetry
glossaries.
E244TestMethodforAtomPercentFissioninUraniumand
4. Summary of the HAFM Test Method
4.1 Helium accumulation fluence monitors (HAFMs) are
1 passive neutron dosimeters that have a measured reaction
ThistestmethodisunderthejurisdictionofASTMCommitteeE10onNuclear
Technology and Applicationsand is the direct responsibility of Subcommittee
product that is helium. The monitors are placed in the reactor
E10.05 on Nuclear Radiation Metrology.
locations of interest, and the helium generated through (n,α)
Current edition approved Jan. 1, 2013. Published January 2013. Originally
reactions accumulates and is retained in the HAFM (or HAFM
approved in 1982. Last previous edition approved in 2007 as E910–07. DOI:
capsule) until the time of removal, perhaps many years later.
10.1520/E0910-07R13.
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 last approved version of this historical standard is referenced on
theASTMwebsite.Theromannumeral-alphabeticaldesignationattheendofsome www.astm.org.
ofthetitlesindicatesthatabriefdescriptionofthisstandardmaybefoundinMatrix See Dictionary of Scientific Terms, 3rd Edition, Sybil P. Parker, Ed., McGraw
E706. Hill, Inc.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E910 − 07 (2013)
Theheliumisthenmeasuredverypreciselybyhigh-sensitivity cussed more fully in Section 13. Generally, they total less than
gas mass spectrometry (1, 2). The neutron fluence is then 5%ofthemeasuredheliumconcentration.Sincetheindividual
directly obtained by dividing the measured helium concentra- corrections are usually known to within 50%, the total error
tion by the spectrum-averaged cross section. Competing he- from these corrections amounts to ≤2%. Sources of uncer-
lium producing reactions, such as (γ,α) do not, except for tainty also lie in the HAFM material mass, isotopic
Be(γ,α), affect the HAFM results. The range of helium composition, and mass spectrometric helium analysis. As
concentrations that can be accurately measured in irradiated indicated in Section 13, however, these uncertainties generally
−14 −1
HAFMs extends from 10 to 10 atom fraction. This range contribute less than 1% of the total uncertainty for routine
permits the HAFMs to be tested in low fluence environments analyses.
yet to work equally well for high fluence situations.
4.5 Applying the above corrections to the measured HAFM
4.2 Typically, HAFMs are either individual small solid
helium concentration, the total incident neutron fluence (over
samples, such as wire segments (3) or miniature encapsulated
the energy range of sensitivity of the HAFM) can be obtained
samplesofsmallcrystalsofpowder (4),asshowninFig.1.As
directly from a knowledge of the spectrum-integrated total
with radiometric dosimetry, different materials are used to
helium production cross section for the particular irradiation
provide different energy sensitivity ranges. Encapsulation is
environment.Atthepresenttime,theuncertaintyinthederived
necessary for those HAFM materials and reactor environment
neutron fluence is mainly due to uncertainty in the spectrum-
combinations where sample melting, sample contamination, or
integrated cross section of the HAFM sensor material rather
loss of generated helium could possibly occur. Additionally,
than the combined uncertainties in the helium determination
encapsulation generally facilitates the handling and identifica-
process. This situation is expected to improve as the cross
tion of the HAFM both prior to and following irradiation. The
sections are more accurately measured, integrally tested in
contentsofHAFMcapsulestypicallyrangefrom0.1to10mg.
benchmark facilities (6), and reevaluated.
4.3 Followingirradiation,encapsulatedHAFMsarecleaned
5. Significance and Use
and identified in preparation for helium analysis. Helium
analysis is then accomplished by vaporizing both the capsule
5.1 The HAFM test method is one of several available
anditscontentsandanalyzingtheheliumintheresultinggases
passiveneutrondosimetrytechniques(see,forexample,Meth-
inahighsensitivitymassspectrometersystem (5).Theamount
ods E854 and E1005). This test method can be used in
4 4 3
of He is determined by measuring the He-to- He isotopic
combinationwithotherdosimetrymethods,or,ifsufficientdata
ratio in the sample gases subsequent to the addition of an
are available from different HAFM sensor materials, as an
accurately calibrated amount of He “spike.” Unencapsulated
alternativedosimetrytestmethod.TheHAFMmethodyieldsa
HAFMs,forexample,pureelementwires,areusuallyetchedto
direct measurement of total helium production in an irradiated
remove a predetermined layer of outer material before helium
sample. Absolute neutron fluence can then be inferred from
analysis (3). This eliminates corrections for both cross con-
this,assumingtheappropriatespectrumintegratedtotalhelium
tamination between samples and α-recoil into or out of the
production cross section. Alternatively, a calibration of the
sample during the irradiation.
composite neutron detection efficiency for the HAFM method
4.4 The He concentration in the HAFM, in general terms, may be obtained by exposure in a benchmark neutron field
wherethefluenceandspectrumaveragedcrosssectionareboth
is proportional to the incident neutron fluence. Consideration
must, however, be made for such factors as HAFM material known (see Matrix E706 IIE).
burnup, neutron self-shielding and flux depression, α-recoil,
5.2 HAFMs have the advantage of producing an end
and neutron gradients. Corrections for these effects are dis-
product, helium, which is stable, making the HAFM method
very attractive for both short-term and long-term fluence
measurements without requiring time-dependent corrections
The boldface numbers in parentheses refer to the list of references appended to
fordecay.HAFMsarethereforeidealpassive,time-integrating
this test method.
FIG. 1 Helium Accumulation Fluence Monitor Capsule
E910 − 07 (2013)
fluence monitors. Additionally, the burnout of the daughter nation of the boron content (7). Boron level down to less than
product, helium, is negligible. 1 wt. ppm can be obtained in this manner.
5.2.1 Many of the HAFM materials can be irradiated in the
5.5 By careful selection of the appropriate HAFM sensor
form of unencapsulated wire segments (see 1.1.2). These
material and its mass, helium concentrations ranging from
−14
segments can easily be fabricated by cutting from a standard
−1
;10 to10 atomfractioncanbegeneratedandmeasured.In
inventoried material lot. The advantage is that encapsulation, 12 27
termsoffluence,thisrepresentsarangeofroughly10 to10
with its associated costs, is not necessary. In several cases,
n/cm . Fluence (>1 MeV) values that may be encountered
unencapsulatedwiressuchasFe,Ni,Al/Co,andCu,whichare
during routine surveillance testing are expected to range from
already included in the standard radiometric (RM) dosimetry
14 20 2
;3×10 to2×10 n/cm , which is well within the range of
sets (Table 1) can be used for both radiometric and helium
the HAFM technique.
accumulation dosimetry. After radiometric counting, the
5.6 The analysis of HAFMs requires an absolute determi-
samples are later vaporized for helium measurement.
nation of the helium content. The analysis system specified in
5.3 The HAFM method is complementary to RM and solid
this test method incorporates a specialized mass spectrometer
state track recorder (SSTR) foils, and has been used as an
in conjunction with an accurately calibrated helium spiking
integral part of the multiple foil method. The HAFM method
system. Helium determination is by isotope dilution with
followsessentiallythesameprincipleastheRMfoiltechnique,
subsequentisotoperatiomeasurement.Thefactthatthehelium
which has been used successfully for accurate neutron dosim-
is stable makes the monitors permanent with the helium
etry for the past 20 to 25 years. Various HAFM sensor
analysis able to be conducted at a later time, often without the
materials exist which have significantly different neutron
inconvenience in handling caused by induced radioactivity.
energy sensitivities from each other. HAFMs containing B
Such systems for analysis exist, and additional analysis facili-
and Li have been used routinely in LMFBR applications in
ties could be reproduced, should that be required. In this
conjunction with RM foils. The resulting data are entirely
respect, therefore, the analytical requirements are similar to
compatible with existing adjustment methods for radiometric
other ASTM test methods (compare with Test Method E244).
foil neutron dosimetry (refer to Method E944).
5.4 An application for the HAFM method lies in the direct
6. Apparatus
analysis of pressure vessel wall scrapings or Charpy block
6.1 High-Sensitivity Gas Mass Spectrometer System, ca-
surveillance samples. Measurements of the helium production
pable of vaporizing both unencapsulated and encapsulated
in these materials can provide in situ integral information on
HAFM materials and analyzing the resulting total helium
the neutron fluence spectrum. This application can provide
content is required. A description of a suitable system is
dosimetry information at critical positions where conventional
contained in Ref (5).
dosimeter placement is difficult if not impossible. Analyses
must first be conducted to determine the boron, lithium, and 6.2 Analytical Microbalance for Accurate Weighing of
other component concentrations, and their homogeneities, so HAFM Samples, minimum specifications: 200-mg capacity
that their possible contributions to the total helium production with an absolute accuracy of 60.5 µg. Working standard
can be determined. Boron (and lithium) can be determined by
masses must be traceable to appropriate national or interna-
converting a fraction of the boron to helium with a known tional mass standards.Additionally, a general purpose balance
thermal neutron exposure. Measurements of the helium in the with a capacity of at least 200 g and an accuracy of 0.1 mg is
material before and after the exposure will enable a determi- required for weighing larger specimens.
TABLE 1 Neutron Characteristics of Candidate HAFM Materials for Reactor Vessel Surveillance
Fission Neutron Spectrum
Principal Helium Producing Thermal Neutron Cross
HAFM Sensor Material
90 % Response
A
Reaction Section, (b)
Cross Section, (mb)
A
Range, (MeV)
Li Li(n,α)T 942 457 0.167–5.66
9 6 6
Be Be(n,α) He ;ra Li . 284 2.5–7.3
10 7
B B(n,α) Li 3838 494 0.066–5.25
14 11
N N(n,α) B . 86.2 1.7–5.7
19 16
F F(n,α) N . 27.6 3.7–9.7
B 27 24
Al Al(n,α) Na . 0.903 6.47–11.9
32 29
S S(n,α) Si . . .
35 32
Cl Cl(n,α) P . ;13 (Cl) 2.6–8.3
B 47 44
Ti Ti(n,α) Ca . 0.634 (Ti) 6.5–12.8
B 56 53
Fe Fe(n,α) Cr . 0.395 (Fe) 5.2–11.9
B 58 55
Ni Ni(n,α) Fe . 5.58 (Ni) 3.9–10.1
B 63 60
Cu Cu(n,α) Co . 0.330 4.74–11.1
316-SS
Helium Production Largely
56 58
from Fe and Ni
PV Steel
J
Charpy Block
A 235
Evaluated U fission neutron spectrum averaged helium production cross section and energy range in which 90 % of the reactions occur. All values are obtained from
ENDF/B-V Gas Production Dosimetry File data. Bracketed terms indicate cross section is for naturally occurring element.
B
Often included in dosimetry sets as a radiometric monitor, either as a pure element foil or wire or, in the case of aluminum, as an allaying material for other elements.
E910 − 07 (2013)
6.3 Laminar flow (optional) clean benches, for use in the HAFMs or combination of HAFM
...
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