Determination of the ²³⁴U isotope content in uranium-bearing materials using high-resolution gamma spectrometry
The paper presents an overview of the research into the available non-destructive methods of determining the ²³⁴U isotope content in uranium-bearing materials. An alternative approach to a problem of detector calibration by the characteristic “intrinsic” efficiency is proposed. Certified reference u...
Збережено в:
| Опубліковано в: : | Вопросы атомной науки и техники |
|---|---|
| Дата: | 2021 |
| Автори: | , , |
| Формат: | Стаття |
| Мова: | English |
| Опубліковано: |
Національний науковий центр «Харківський фізико-технічний інститут» НАН України
2021
|
| Теми: | |
| Онлайн доступ: | https://nasplib.isofts.kiev.ua/handle/123456789/195113 |
| Теги: |
Додати тег
Немає тегів, Будьте першим, хто поставить тег для цього запису!
|
| Назва журналу: | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| Цитувати: | Determination of the ²³⁴U isotope content in uranium-bearing materials using high-resolution gamma spectrometry / D.V. Kutniy, D.D. Burdeinyi, N.N. Savchenko // Problems of Atomic Science and Technology. — 2021. — № 3. — С. 81-85. — Бібліогр.: 16 назв. — англ. |
Репозитарії
Digital Library of Periodicals of National Academy of Sciences of Ukraine| id |
nasplib_isofts_kiev_ua-123456789-195113 |
|---|---|
| record_format |
dspace |
| spelling |
Kutniy, D.V. Burdeinyi, D.D. Savchenko, N.N. 2023-12-03T13:33:50Z 2023-12-03T13:33:50Z 2021 Determination of the ²³⁴U isotope content in uranium-bearing materials using high-resolution gamma spectrometry / D.V. Kutniy, D.D. Burdeinyi, N.N. Savchenko // Problems of Atomic Science and Technology. — 2021. — № 3. — С. 81-85. — Бібліогр.: 16 назв. — англ. 1562-6016 PACS: 29.30Kv DOI: https://doi.org/10.46813/2023-133-081 https://nasplib.isofts.kiev.ua/handle/123456789/195113 The paper presents an overview of the research into the available non-destructive methods of determining the ²³⁴U isotope content in uranium-bearing materials. An alternative approach to a problem of detector calibration by the characteristic “intrinsic” efficiency is proposed. Certified reference uranium-bearing materials CRM 969 and CRM 146 (a range of ²³⁵U enrichments studied was 0.3…93%) were used as test samples, measurements were carried out with a wide-range energy detector based on the high-purity BeGe 3830 germanium (Canberra, USA) with 38 cm2 area and 3 cm thickness. An approach used for the “intrinsic” efficiency calibration for the ²³⁴U analysis permits to decrease the measurement error to 7.5% in the whole range of ²³⁵U enrichment (from 0.3 to 93%) and ²³⁴U concentrations (20 to 9800 μg/g). The proposed method does not demand standard samples for equipment calibration and does not depend on the physical (chemical) form of the investigated material and measurement geometry. Проаналізовано існуючі методи неруйнівного визначення кількісного вмісту ізотопу ²³⁴U в уранвміщуючих матеріалах, а також запропоновано альтернативний метод, заснований на підході калібрування детектора за «характерною» ефективністю. В якості досліджуваних зразків використовували сертифіковані стандартні зразки уранвміщуючих матеріалів CRM 969 і CRM 146 (інтервал збагачень по ²³⁵U (0,3…93%), вимірювання проводили за допомогою широкодіапазонного детектора на основі германію високої чистоти типу BeGe 3830 (Canberra, США) площею 38 см2 і товщиною 3 см. Використання підходу калібрування детектора за «характерною» ефективністю для аналізу ²³⁴U призводить до зниження похибки вимірювань до 7,5% у всьому діапазоні збагачень по ²³⁵U (0,3…93%) і концентрацій ²³⁴U (20…9800 μг/г). Запропонований метод не вимагає наявності стандартних зразків для калібрування обладнання, не залежить від фізичної (хімічної) форми досліджуваних матеріалів і геометрії вимірювань. Проанализированы существующие методы неразрушающего определения количественного содержания изотопа ²³⁴U в урансодержащих материалах, а также предложен альтернативный метод, основанный на подходе калибровки детектора по «характерной» эффективности. В качестве исследуемых образцов использовали сертифицированные стандартные образцы урансодержащих материалов CRM 969 и CRM 146 (интервал исследуемых обогащений по ²³⁵U (0,3…93%), измерения проводили с помощью широкодиапазонного детектора на основе германия высокой чистоты типа BeGe 3830 (Canberra, США) площадью 38 см2 и толщиной 3 см. Использование подхода калибровки детектора по «характерной» эффективности для анализа ²³⁴U приводит к снижению погрешности измерений до 7,5% во всем диапазоне обогащений по ²³⁵U (0,3…93%) и исследуемых концентраций ²³⁴U (20…9800 μг/г). Предлагаемый метод не требует наличия стандартных образцов для калибровки оборудования, не зависит от физической (химической) формы исследуемых материалов и геометрии измерений. en Національний науковий центр «Харківський фізико-технічний інститут» НАН України Вопросы атомной науки и техники Experimental methods and processing of data Determination of the ²³⁴U isotope content in uranium-bearing materials using high-resolution gamma spectrometry Визначення вмісту ізотопу ²³⁴U в уранвміщуючих матеріалах методом гамма-спектрометрії високого розподілення Определение содержания изотопа ²³⁴U в урансодержащих материалах методом гамма-спектрометрии высокого разрешения Article published earlier |
| institution |
Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| collection |
DSpace DC |
| title |
Determination of the ²³⁴U isotope content in uranium-bearing materials using high-resolution gamma spectrometry |
| spellingShingle |
Determination of the ²³⁴U isotope content in uranium-bearing materials using high-resolution gamma spectrometry Kutniy, D.V. Burdeinyi, D.D. Savchenko, N.N. Experimental methods and processing of data |
| title_short |
Determination of the ²³⁴U isotope content in uranium-bearing materials using high-resolution gamma spectrometry |
| title_full |
Determination of the ²³⁴U isotope content in uranium-bearing materials using high-resolution gamma spectrometry |
| title_fullStr |
Determination of the ²³⁴U isotope content in uranium-bearing materials using high-resolution gamma spectrometry |
| title_full_unstemmed |
Determination of the ²³⁴U isotope content in uranium-bearing materials using high-resolution gamma spectrometry |
| title_sort |
determination of the ²³⁴u isotope content in uranium-bearing materials using high-resolution gamma spectrometry |
| author |
Kutniy, D.V. Burdeinyi, D.D. Savchenko, N.N. |
| author_facet |
Kutniy, D.V. Burdeinyi, D.D. Savchenko, N.N. |
| topic |
Experimental methods and processing of data |
| topic_facet |
Experimental methods and processing of data |
| publishDate |
2021 |
| language |
English |
| container_title |
Вопросы атомной науки и техники |
| publisher |
Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| format |
Article |
| title_alt |
Визначення вмісту ізотопу ²³⁴U в уранвміщуючих матеріалах методом гамма-спектрометрії високого розподілення Определение содержания изотопа ²³⁴U в урансодержащих материалах методом гамма-спектрометрии высокого разрешения |
| description |
The paper presents an overview of the research into the available non-destructive methods of determining the ²³⁴U isotope content in uranium-bearing materials. An alternative approach to a problem of detector calibration by the characteristic “intrinsic” efficiency is proposed. Certified reference uranium-bearing materials CRM 969 and CRM 146 (a range of ²³⁵U enrichments studied was 0.3…93%) were used as test samples, measurements were carried out with a wide-range energy detector based on the high-purity BeGe 3830 germanium (Canberra, USA) with 38 cm2 area and 3 cm thickness. An approach used for the “intrinsic” efficiency calibration for the ²³⁴U analysis permits to decrease the measurement error to 7.5% in the whole range of ²³⁵U enrichment (from 0.3 to 93%) and ²³⁴U concentrations (20 to 9800 μg/g). The proposed method does not demand standard samples for equipment calibration and does not depend on the physical (chemical) form of the investigated material and measurement geometry.
Проаналізовано існуючі методи неруйнівного визначення кількісного вмісту ізотопу ²³⁴U в уранвміщуючих матеріалах, а також запропоновано альтернативний метод, заснований на підході калібрування детектора за «характерною» ефективністю. В якості досліджуваних зразків використовували сертифіковані стандартні зразки уранвміщуючих матеріалів CRM 969 і CRM 146 (інтервал збагачень по ²³⁵U (0,3…93%), вимірювання проводили за допомогою широкодіапазонного детектора на основі германію високої чистоти типу BeGe 3830 (Canberra, США) площею 38 см2 і товщиною 3 см. Використання підходу калібрування детектора за «характерною» ефективністю для аналізу ²³⁴U призводить до зниження похибки вимірювань до 7,5% у всьому діапазоні збагачень по ²³⁵U (0,3…93%) і концентрацій ²³⁴U (20…9800 μг/г). Запропонований метод не вимагає наявності стандартних зразків для калібрування обладнання, не залежить від фізичної (хімічної) форми досліджуваних матеріалів і геометрії вимірювань.
Проанализированы существующие методы неразрушающего определения количественного содержания изотопа ²³⁴U в урансодержащих материалах, а также предложен альтернативный метод, основанный на подходе калибровки детектора по «характерной» эффективности. В качестве исследуемых образцов использовали сертифицированные стандартные образцы урансодержащих материалов CRM 969 и CRM 146 (интервал исследуемых обогащений по ²³⁵U (0,3…93%), измерения проводили с помощью широкодиапазонного детектора на основе германия высокой чистоты типа BeGe 3830 (Canberra, США) площадью 38 см2 и толщиной 3 см. Использование подхода калибровки детектора по «характерной» эффективности для анализа ²³⁴U приводит к снижению погрешности измерений до 7,5% во всем диапазоне обогащений по ²³⁵U (0,3…93%) и исследуемых концентраций ²³⁴U (20…9800 μг/г). Предлагаемый метод не требует наличия стандартных образцов для калибровки оборудования, не зависит от физической (химической) формы исследуемых материалов и геометрии измерений.
|
| issn |
1562-6016 |
| url |
https://nasplib.isofts.kiev.ua/handle/123456789/195113 |
| citation_txt |
Determination of the ²³⁴U isotope content in uranium-bearing materials using high-resolution gamma spectrometry / D.V. Kutniy, D.D. Burdeinyi, N.N. Savchenko // Problems of Atomic Science and Technology. — 2021. — № 3. — С. 81-85. — Бібліогр.: 16 назв. — англ. |
| work_keys_str_mv |
AT kutniydv determinationofthe234uisotopecontentinuraniumbearingmaterialsusinghighresolutiongammaspectrometry AT burdeinyidd determinationofthe234uisotopecontentinuraniumbearingmaterialsusinghighresolutiongammaspectrometry AT savchenkonn determinationofthe234uisotopecontentinuraniumbearingmaterialsusinghighresolutiongammaspectrometry AT kutniydv viznačennâvmístuízotopu234uvuranvmíŝuûčihmateríalahmetodomgammaspektrometríívisokogorozpodílennâ AT burdeinyidd viznačennâvmístuízotopu234uvuranvmíŝuûčihmateríalahmetodomgammaspektrometríívisokogorozpodílennâ AT savchenkonn viznačennâvmístuízotopu234uvuranvmíŝuûčihmateríalahmetodomgammaspektrometríívisokogorozpodílennâ AT kutniydv opredeleniesoderžaniâizotopa234uvuransoderžaŝihmaterialahmetodomgammaspektrometriivysokogorazrešeniâ AT burdeinyidd opredeleniesoderžaniâizotopa234uvuransoderžaŝihmaterialahmetodomgammaspektrometriivysokogorazrešeniâ AT savchenkonn opredeleniesoderžaniâizotopa234uvuransoderžaŝihmaterialahmetodomgammaspektrometriivysokogorazrešeniâ |
| first_indexed |
2025-11-25T13:26:51Z |
| last_indexed |
2025-11-25T13:26:51Z |
| _version_ |
1850515574580314112 |
| fulltext |
ISSN 1562-6016. ВАНТ. 2021. № 3(133) 81
https://doi.org/10.46813/2023-133-081
DETERMINATION OF THE 234U ISOTOPE CONTENT
IN URANIUM-BEARING MATERIALS USING HIGH-RESOLUTION
GAMMA SPECTROMETRY
D.V. Kutniy1, D.D. Burdeinyi1, N.N. Savchenko2
1National Science Center “Kharkov Institute of Physics and Technology”, Kharkiv, Ukraine;
2V.N. Karazin Kharkiv National University, Kharkiv, Ukraine
E-mail: d_kutniy@kipt.kharkov.ua
The paper presents an overview of the research into the available non-destructive methods of determining the
234U isotope content in uranium-bearing materials. An alternative approach to a problem of detector calibration by
the characteristic “intrinsic” efficiency is proposed. Certified reference uranium-bearing materials CRM 969 and
CRM 146 (a range of 235U enrichments studied was 0.3…93%) were used as test samples, measurements were car-
ried out with a wide-range energy detector based on the high-purity BeGe 3830 germanium (Canberra, USA) with
38 cm2 area and 3 cm thickness. An approach used for the “intrinsic” efficiency calibration for the 234U analysis
permits to decrease the measurement error to 7.5% in the whole range of 235U enrichment (from 0.3 to 93%) and
234U concentrations (20 to 9800 g/g). The proposed method does not demand standard samples for equipment cali-
bration and does not depend on the physical (chemical) form of the investigated material and measurement geometry.
PACS: 29.30Kv
INTRODUCTION
Natural uranium is a mixture of three isotopes: 238U
(the content in natural mixture 99.280 wt. %), 235U
(0.714 wt. %), and 234U (0.006 wt. %) [1]. A 234U iso-
tope is radiogenic, not a primary one, it is a part of the
radioactive series of 238U. Despite an utterly low content
of 234U, its activity in natural uranium is almost equal to
the 238U activity, as these isotopes are in balance. Thus,
234U and 238U contribute each more than 49% to the total
activity of natural uranium.
When making fuel for nuclear plants, natural ura-
nium is enriched in order to increase the 235U isotope
content. At the same time, the content of 234U isotope, as
even lighter, also increases. Although in the nuclear fuel
the content of 234U remains at the level of hundredths of
a percent its activity becomes predominant. That is why,
from a sanitary point of view, 234U carries the greatest
radiological hazard to the staff health that indicates an
urgency of determining even its small contents.
Furthermore, in conformity with the nuclear fuel cy-
cle (NFC) processes, the 234U content limit in the raw
material of natural and enriched uranium hexafluoride
(UF6) is regulated by ASTM C 787 and ASTM C 996
standards at 60 and 11 g/g of U, respectively. Conse-
quently, the quantitative identification of 234U is urgent
both for the radiation safety and for the implementation
of analytical quality control of NFC products.
Currently the destructive methods of analysis (in-
ductively coupled plasma mass spectrometry, alpha
spectrometry) of the isotopic composition of uranium-
bearing materials are well developed [2 - 5]. One of the
disadvantages of destructive methods is complex and
time-consuming sample preparation: for example, for
alpha spectrometry it is necessary to separate com-
pletely the analyte from the matrix and to transfer the
sample into the thin-disk mold using electrodeposition,
evaporation, co-precipitation [6]. Therefore, the non-
destructive methods with a simplified sample prepara-
tion are quickly developing. In addition, the use of such
methods decreases the time of direct contact with the
sample that is especially important when working with
radioactive materials and does not lead to the formation
of radioactive waste, which subsequently should be dis-
posed.
Gamma-ray spectrometry, as a non-destructive
method of analysis of the isotopic composition of ura-
nium-bearing materials, began to be used in the 1970s
[7, 8]. To date, available are the Canberra's commercial
software for uranium isotope analysis: MGAU (Multi-
Group Analysis for Uranium) and FRAM (Fixed-energy
Response-function Analysis with Multiple Efficiency)
developed in U.S. national laboratories (LLNL, LANL)
[9, 10].
As a result of processing the gamma spectrometric
data the software calculates the content of isotopes 238U,
235U, 234U (and in some cases 236U). As these software
codes were developed primarily to determine the en-
richment of uranium-bearing materials, the metrological
characteristics of 235U, 238U measurements were thor-
oughly investigated and determined [11 - 13], in con-
trast with the 234U isotope. The paper [14] shows that
the error of determining the 234U content using MGAU
code can range from 20 to 50%. So, the purpose of this
study was to analyze the available non-destructive
methods and to develop an alternative approach for de-
termining the isotope 234U content in uranium-bearing
materials as well as to substantiate the choice of the best
method for providing the radiation safety and analytical
quality control of NFC products.
EXPERIMENTAL TECHNIQUE
Investigations were carried out using certified refer-
ence uranium-bearing materials (CRM 969: level of
enrichment from 0.3 to 4 wt. % and CRM 146: level of
enrichment from 20 to 93 wt. %) manufactured by the
New Brunswick Laboratory of USA. The characteristics
of the samples are given in Table 1.
ISSN 1562-6016. ВАНТ. 2021. № 3(133) 82
Table 1
Interferences of the main analytic lines of K and L series
elements with uranium lines of L and M series
Sample ID 235U, wt.% 238U, wt.% 234U, wt.%
031 0.3166
±0.0002
99.6668
±0.0004
0.002
±0.0002
071 0.7119
±0.0005
99.2828
±0.0004
0.0052
±0.0002
194 1.9420
±0.0014
98.0404
±0.0018
0.0171
±0.0002
295 2.9492
±0.0021
97.0196
±0.0029
0.0279
±0.0004
446 4.4623
±0.0032
95.4950
±0.0032
0.0359
±0.0003
NBL0013 20.1070
±0.0200
79.5470
±0.0200
0.1486
±0.0004
NBL0014 52.4880
±0.0420
46.8760
±0.0430
0.3718
±0.0010
NBL0015 93.1703
±0.0052
5.5559
±0.0053
0.9800
±0.0029
The gamma-ray spectra of the samples investigated
were acquired using a broad-energy detector based on
the high-purity germanium of BeGe 3830 type (Can-
berra, USA) with a 38 cm2 area and 3 cm thickness hav-
ing the energy resolution of 0.468 at 5.9 keV; 0.572 at
122 keV, and 1.51 at 1.332 keV.
Experimental spectrometric data were processed us-
ing the commercial program packages MGAU and
FRAM. Besides, the 234U isotope content evaluation was
performed using an empirical equation from [15],
234 235 2 235( ) 0.0015 0.0058 ( ) 0.000054 ( )C U C U C U ,
where 234( )C U is the 234U content; 235( )C U is the 235U
content (enrichment).
An alternative approach for the 234U content deter-
mination was based on the approach of “intrinsic” effi-
ciency calibration proposed in the studies of the age-
dating of uranium-bearing materials [16]. The efficiency
calibration is “intrinsic” in the sense that it relates to a
specific gamma spectrum, i.e. for each sample under
study (a set of spectral data) it is necessary to perform
its own “intrinsic” calibration. A desired content can be
derived from the activity ratio of isotopes 234U and 235U.
The isotope activity in the sample is written as
absA P I , where P is the detector counting rate at
the selected peak of photoelectric absorption; abs is the
detector absolute efficiency and I is the emission inten-
sity of gamma-ray of a given energy. The main problem
in determining the absolute values of the isotope activity
is to find abs which depends on many factors (gamma-
ray energy, detector and sample characteristics, dis-
tance, absorbers, etc.). This problem can be avoided
with the use of isotope activity ratio. In the region of
gamma-ray energies from 120 to 210 keV (Fig. 1) there
are lines of 234U isotope (120.90 keV, I = 0.0342%) and
of 235U isotope (143.76 keV, I = 10.96%; 163.33 keV,
I = 5.08%; 185.72 keV, I = 57.20%, and 205.31 keV,
I = 5.01%). By rewriting the activity equation as
absA P I , plotting the ratio P I versus 235U
gamma-ray energy (E) and extrapolating the resulting
dependence by the linear or quadratic function into the
120 keV energy range, we obtain the value of
235 235
120.90 120.90
U UP I equal to the detection “intrinsic” effi-
ciency of the conventional 235U gamma-quanta with
120.90 keV energy at a fixed activity value
( 235 120.90U
absA ).
Fig. 1. Gamma-spectrum of the certified reference
uranium-bearing material ID No 194 in the energy
range from 120 to 210 keV
Then the activity ratio 234U/235U can be written as:
234 120.90 234 234
120.90 120.90
235 120.90 235 235
120.90 120.90
U U U
abs
U U U
abs
A P I
A P I
.
By canceling the values of absolute efficiency 120.90
abs
finally we get:
234 234234
120.90 120.90
235 235 235
120.90 120.90
U UU
U U U
P IA
A P I
.
Having the resulting ratio of the 234U and 235U iso-
tope activities and determining the content of 235U in the
sample by the software codes MGAU or FRAM, and
taking into account the values of their specific activities
2.30108 and 7.98104 Bk/g it is possible to calculate
the 234U isotope content. The proposed method elimi-
nates the need of standard samples for an equipment
calibration, does not depend on the physical (chemical)
form of materials under study and geometry of meas-
urements.
RESULTS AND DISCUSSION
Fig. 2 shows the uranium isotope activity contribu-
tions into the total activity of the certified reference
samples with various enrichments (uranium mass
~ 169 g in the samples CRM 969 and ~ 194 g in the
samples CRM 146). It is seen that, indeed, starting with
the contents of 235U more than 0.7 wt. %, the 234U iso-
tope activity becomes predominant and reaches ~ 90%
of the total activity for highly enriched uranium.
Table 2 gives the results of determining the 234U iso-
tope content using the software codes MGAU and
FRAM, as well as the empirical equation described
above.
In the Table, besides the 234U content values, the
standard deviations and relative measurement errors (
and ) are given. The research results show that the
ISSN 1562-6016. ВАНТ. 2021. № 3(133) 83
available methods of 234U analysis are, most likely
quantitative, especially for the samples with natural
(0.7 wt. %) and depleted (0.3 wt. %) 235U contents.
Fig. 2. Contribution of uranium isotope activities into
the total activity of uranium-bearing materials versus
their enrichment: 1 – activity of 235U;
2 – activity of 234U; 3 – activity of 238U
The results of the MGAU code application leads to
the underestimation of the 234U content in the entire
range of material enrichments, while the error by for-
mula [15] is of a diverse character. There is observed a
tendency to the measurement error decrease with en-
richment increasing, so the FRAM code application for
analysis of low-enriched samples allows determining
the 234U content with an error margin less than 10%.
Standard deviations () of measurement results, de-
pending mainly on the 120.90 keV line statistic and
spectral data processing algorithm, are maximum for ID
samples No 031 and No 071 (50 and 67% for MGAU
code and 64 and 26% for FRAM code), and they mono-
tonically decrease to 20 and 3%, respectively, with en-
richment increasing.
To develop an alternative method for determination
of the 234U content based on the “intrinsic” efficiency
calibration, the P/I ratios were plotted, as a function of
235U gamma-ray energy (143.76; 163.33; 185.72, and
205.31 keV), and then approximated by a quadratic or
linear function (Fig. 3). Thus, the coefficients A1, B1,
B2, the correlation coefficients R2 and the mean-square
deviation (standard uncertainty) were found. The selec-
tion of the approximation function was based on an
evaluation of the correlation coefficient and mean-
square deviation (MSD), the maximum value of the
latter did not exceed 0.9%.
Table 2
Results of determining the 234U isotope content using the software codes MGAU and FRAM,
as well as the empirical formula [15]
MGAU FRAM By equation [15] Sample ID
234( )C U ,
wt. %
, % 234( )C U ,
wt. %
, % 234( )C U ,
wt. %
, %
031 0.00400.0020 +100.00 0.00280.0018 +40.00 0.0033 +67.10
071 0.00300. 0020 -42.31 0.00700.0018 +34.62 0.0057 +8.77
194 0.01100.0030 -35.67 0.01690.0018 -1.17 0.0129 -24.17
295 0.02000.0040 -28.32 0.02540.0019 -8.96 0.0191 -31.63
446 0.02500.0050 -30.36 0,03770.0021 +5.01 0.0285 -20.73
NBL0013 0.11400.0230 -23,29 0.14740.0090 -0,81 0.1399 -5.83
NBL0014 0.27300.0550 -26.57 0.23660.0067 -36.36 0.4547 +22.30
NBL0015 0.72700.1460 -25.82 0.89300.0254 -8.88 1.0106 +3.13
a b
Fig. 3. Results of the approximation of the P/I ratio versus 235U gamma-ray energy and its extrapolation
into the 120 keV energy range: a – sample ID No 031; b – sample ID No NBL0015
The resulting functions were used to find the ratio
235 235
120.90 120.90
U UP I and further, determining 234 234
120.90 120.90
U UP I
by processing the 120.90 keV peak from the obtained
spectral data, the ratio of activities 234 235U UA A was
ISSN 1562-6016. ВАНТ. 2021. № 3(133) 84
calculated and, as a consequence, the 234U isotope con-
tent was determined. The calculation results are given in
Table 3.
The maximum standard deviation values () are 28
and 5% for depleted and natural uranium. This is ex-
plained by the low 234U peak statistic (120.90 keV) in
these samples (0.000136 and 0.0082 counts/s) and, as a
consequence, by a significant uncertainty in the analysis
of its area. For all other enriched samples, the standard
deviation value ranges from 1.0 to 2.5%. The measure-
ment error monotonically decreases with enrichment
increasing that is also explained by the increase of the
234U, 235U peak intensities and by the volume of their
statistics.
Table 3
Results of the 234U isotope content determination using
the method of “intrinsic” efficiency calibration
Sample ID Certified
234( )C U ,
wt. %
Measured
234( )C U ,
wt. %
, % , %
031 0.0020 0.001854
±0.000527
28.41 -7.30
071 0.0052 0.005574
±0.000280
5.02 +7.20
194 0.0171 0.018327
±0.000394
2.15 +7.18
295 0.0279 0.029392
±0.000355
1.21 +5.35
446 0.0359 0.037466
±0.000480
1.28 +4.36
NBL0013 0.1486 0.154782
±0.002870
1.85 +4.15
NBL0014 0.3718 0.382856
±0.009655
2.52 +2.97
NBL0015 0.9800 1.007102
±0.025198
2.50 +2.77
The relative measurement error () behaves simi-
larly to the standard deviation for the same reasons. An
insignificant systematic overestimation of the 234U con-
tent value is associated with the error of experimental
data approximation by a quadratic function, and proba-
bly this problem can be solved by selection of an alter-
native function.
To apply the “intrinsic” efficiency method for detec-
tor calibration, in order to determine the ratio of iso-
topes activities, the presence of their sufficiently intense
lines with close energies in the spectrum is required. For
234U and 235U isotopes this condition is optimally satis-
fied, mechanisms and effects of the interaction between
gamma-ray and materials of the sample, detector and
container are identical for the specified geometry of
measurements in a narrow range of energies. Conse-
quently, the isotope activity ratio under consideration
can be reliably derived by approximation of the normal-
ized counting rates in the photoelectric absorption peaks
of 235U followed by extrapolation of this dependence
into the energy range of 234U gamma-ray.
The lower detection limit of values 234( )C U
0.0020 wt. % (20 µg/g) is consistent, by the value order,
with the maximum allowable contents of 234U in the raw
material of natural and enriched UF6 that indicates the
possibility of applying the proposed method for the ana-
lytical quality control of NFC products. It should be
noted that the approaches described in this paper sug-
gest a uniform distribution of uranium isotopes in the
matrix and the absence of a significant gamma-ray ab-
sorption. For example, the characterization of radioac-
tive waste may require further research to set the sensi-
tivity limits of the proposed method.
CONCLUSIONS
The available methods of non-destructive determina-
tion of 234U isotope content in uranium-bearing materi-
als have been analyzed, and an alternative approach of
“intrinsic” efficiency calibration of the detector is pro-
posed.
It is shown that the use of up-to-day commercial
software products for isotopic uranium analysis does not
allow to reliably evaluate the content of 234U isotope in
depleted and natural samples due to a significant meas-
urement error (from 35 to 100%). In the case of en-
riched uranium analysis, the MGAU software code sys-
tematically underestimates the 234U content by
20…30%, and the FRAM code can be used in the range
of 235U enrichments from 2 to 20%.
Features of the interaction between the gamma-ray
and materials of the sample and detector in the energy
range of the most intense lines of 234U and 235U
(120…210 keV) provide an opportunity to implement
the approach of “intrinsic” efficiency calibration for
234U content analysis. As a result, the error of the 234U
content analysis did not exceed 7.5% in the entire range
of 235U (0.3…93%) enrichment and 234U concentrations
(20…9800 µg/g).
REFERENCES
1. A.A. Maslov, G.V. Kalyatskaya, G.N. Amelina,
A.Yu. Vodyakin, N.B. Yegorov. Technology of ura-
nium and plutonium: Textbook. Tomsk Polytechnic
University, Tomsk, 2007, 97 p.
2. I. Bowen, A. Walder, T. Hodgson, R. Parrish. High
precision and high accuracy isotopic measurement
of uranium using lead and thorium calibration solu-
tion by inductively coupled plasma – multiple col-
lector – mass spectrometry // Application of induc-
tively coupled plasma mass spectrometry to ra-
dionuclide determinations: Second Volume. 1998,
ASTM STP 1344, p. 22-31.
3. C 1477-00. Standard test method for isotopic abun-
dance analysis of uranium hexafluoride by multi-
collector inductively coupled plasma mass spec-
trometry // Annual book of ASTM standards. 2001,
v. 12.01, p. 1012-1017.
4. A.V. Saprygin, B.G. Dzhavaev, A.A. Makarov. The
analytical characteristics of ICP-MS-MC for deter-
mining the isotopic composition of uranium, ob-
tained using high-accuracy standard samples // Ana-
lytics and Control. 2003, № 1, p. 68-73.
5. A.A. Odintsov. Alpha-spectrometric determination
of uranium isotope composition in liquid radioactive
waste of the “Ukrytie” object // Problems of Safety
of Nuclear Power Plants and Chernobyl. 2008,
№ 10, p. 147-155.
ISSN 1562-6016. ВАНТ. 2021. № 3(133) 85
6. A.R. Gubal. Direct elemental and isotopic analysis
of solid-phase nonconducting materials using a
time-of-flight mass spectrometer with pulsed glow
discharge: Ph.D. thesis. 2015, St. Petersburg, 172 p.
7. T.D. Reilly, R.B. Walton, J.L. Parker. The enrich-
ment meter – a simple method for measuring iso-
topic enrichment: Report # LA-4605-MS, LANL,
Los Alamos, USA. 1970, 19 p.
8. R. Harry, J. Aaldijk, J. Braak. Gamma-spectroscopic
determination of isotopic composition without use of
standards // Proceedings of IAEA symposium on
Safeguarding Nuclear Materials, Vienna, Austria.
1975, p. 235.
9. R. Gunnik, W. Ruther, P. Miller, J. Goerten.
MGAU: A new analysis code for measuring U-235
enrichments in arbitrary samples: Preprint UCRL-
JC-114713, LLNL, Livermore, USA. 1994, p. 1-4.
10. D.T. Vo, Th.E. Sampson. Uranium isotopic analysis
with the FRAM isotopic analysis code: Report # LA-
13580, LANL, Los Alamos, USA. 1999, 24 p.
11. M. Koskelo, B. McGinnis, D. Vo, T. Wang,
P. Peerani, G. Renha, F. Cordeiro. Sustainability of
gamma-ray isotopic evaluation codes: Report # LA-
UR-10-03727, LANL, Los Alamos, USA. 2010, 15 p.
12. M. Koskelo, J. Chapman, J. Marsh, S. Stevens.
Comparison of the performance of different uranium
enrichment analysis codes using range of detector
types // Proceedings of the 7-th International Con-
ference on Facility Operations – Safeguard Inter-
face, Oak Ridge (USA). 2004, p. 1-9.
13. D. Vo, Th. Sampson. Uranium isotopic analysis with
the FRAM isotopic analysis code: Report # LA-
13580, LANL, Los Alamos, USA. 1999, 30 p.
14. A.N. Berlizov, V.V. Tryshyn. Study of the MGAU
applicability to accurate isotopic characterization of
uranium samples: Report # IAEA-SM-367/14/05/P,
IAEA, Vienna, Austria. 2001, 13 p.
15. T. Rucker, C. Johnson. Calculation of uranium iso-
topic activity composition based on data from vari-
ous assay methods [Electronic resource] / Bioassay
Analytical Environmental Radiochemistry. – Way to
access: http://www.lanl.gov/BAER-Conference
/BAERCon-43docs.html.
16. C. Nguyen, J. Zsigrai. Gamma-spectrometric ura-
nium age-dating using intrinsic efficiency calibration
// Nucl. Instr. Meth. 2006, v. B243, p. 187-192.
Article received 15.02.2021
ОПРЕДЕЛЕНИЕ СОДЕРЖАНИЯ ИЗОТОПА 234U В УРАНСОДЕРЖАЩИХ МАТЕРИАЛАХ
МЕТОДОМ ГАММА-СПЕКТРОМЕТРИИ ВЫСОКОГО РАЗРЕШЕНИЯ
Д.В. Кутний, Д.Д. Бурдейный, Н.Н. Савченко
Проанализированы существующие методы неразрушающего определения количественного содержания
изотопа 234U в урансодержащих материалах, а также предложен альтернативный метод, основанный на под-
ходе калибровки детектора по «характерной» эффективности. В качестве исследуемых образцов использо-
вали сертифицированные стандартные образцы урансодержащих материалов CRM 969 и CRM 146 (интер-
вал исследуемых обогащений по 235U (0,3…93%), измерения проводили с помощью широкодиапазонного
детектора на основе германия высокой чистоты типа BeGe 3830 (Canberra, США) площадью 38 см2 и тол-
щиной 3 см. Использование подхода калибровки детектора по «характерной» эффективности для анализа
234U приводит к снижению погрешности измерений до 7,5% во всем диапазоне обогащений по 235U
(0,3…93%) и исследуемых концентраций 234U (20…9800 г/г). Предлагаемый метод не требует наличия
стандартных образцов для калибровки оборудования, не зависит от физической (химической) формы иссле-
дуемых материалов и геометрии измерений.
ВИЗНАЧЕННЯ ВМІСТУ ІЗОТОПУ 234U В УРАНВМІЩУЮЧИХ МАТЕРІАЛАХ МЕТОДОМ
ГАММА-СПЕКТРОМЕТРІЇ ВИСОКОГО РОЗПОДІЛЕННЯ
Д.В. Кутній, Д.Д. Бурдейний, Н.М. Савченко
Проаналізовано існуючі методи неруйнівного визначення кількісного вмісту ізотопу 234U в уранвміщую-
чих матеріалах, а також запропоновано альтернативний метод, заснований на підході калібрування детекто-
ра за «характерною» ефективністю. В якості досліджуваних зразків використовували сертифіковані стандар-
тні зразки уранвміщуючих матеріалів CRM 969 і CRM 146 (інтервал збагачень по 235U (0,3...93%), вимірю-
вання проводили за допомогою широкодіапазонного детектора на основі германію високої чистоти типу
BeGe 3830 (Canberra, США) площею 38 см2 і товщиною 3 см. Використання підходу калібрування детектора
за «характерною» ефективністю для аналізу 234U призводить до зниження похибки вимірювань до 7,5% у
всьому діапазоні збагачень по 235U (0,3...93%) і концентрацій 234U (20...9800 г/г). Запропонований метод не
вимагає наявності стандартних зразків для калібрування обладнання, не залежить від фізичної (хімічної)
форми досліджуваних матеріалів і геометрії вимірювань.
|