A system for sorting radioactive waste of the Chernobyl exclusion zone
This work is extending the research started in 1998, which are directed on development of a Chernobyl origin radioactive waste sorting system. In this paper the principal scheme and possible engineering solutions of the system for sorting the waste placed in temporary localization dumps of the Chern...
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| Цитувати: | A system for sorting radioactive waste of the Chernobyl exclusion zone / R.P. Slabospitzkij, V.B. Ganenko, V.T. Bukov, O.G. Savchuk, V.V. Selukova, V.G. Batij, V.O. Kouzmenko, V.I. Stoyanov // Вопросы атомной науки и техники. — 2001. — № 1. — С. 73-80. — Бібліогр.: 15 назв. — англ. |
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Slabospitzkij, R.P. Ganenko, V.B. Bukov, V.T. Savchuk, O.G. Selukova, V.V. Batij, V.G. Kouzmenko, V.O. Stoyanov, V.I. 2015-03-18T17:19:36Z 2015-03-18T17:19:36Z 2001 A system for sorting radioactive waste of the Chernobyl exclusion zone / R.P. Slabospitzkij, V.B. Ganenko, V.T. Bukov, O.G. Savchuk, V.V. Selukova, V.G. Batij, V.O. Kouzmenko, V.I. Stoyanov // Вопросы атомной науки и техники. — 2001. — № 1. — С. 73-80. — Бібліогр.: 15 назв. — англ. 1562-6016 PACS:28.41.Kw. https://nasplib.isofts.kiev.ua/handle/123456789/78515 This work is extending the research started in 1998, which are directed on development of a Chernobyl origin radioactive waste sorting system. In this paper the principal scheme and possible engineering solutions of the system for sorting the waste placed in temporary localization dumps of the Chernobyl Exclusion Zone are described. en Національний науковий центр «Харківський фізико-технічний інститут» НАН України Вопросы атомной науки и техники Application of the nuclear methods A system for sorting radioactive waste of the Chernobyl exclusion zone Система сортировки радиоактивных отходов чернобыльской зоны отчуждения Article published earlier |
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Digital Library of Periodicals of National Academy of Sciences of Ukraine |
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| title |
A system for sorting radioactive waste of the Chernobyl exclusion zone |
| spellingShingle |
A system for sorting radioactive waste of the Chernobyl exclusion zone Slabospitzkij, R.P. Ganenko, V.B. Bukov, V.T. Savchuk, O.G. Selukova, V.V. Batij, V.G. Kouzmenko, V.O. Stoyanov, V.I. Application of the nuclear methods |
| title_short |
A system for sorting radioactive waste of the Chernobyl exclusion zone |
| title_full |
A system for sorting radioactive waste of the Chernobyl exclusion zone |
| title_fullStr |
A system for sorting radioactive waste of the Chernobyl exclusion zone |
| title_full_unstemmed |
A system for sorting radioactive waste of the Chernobyl exclusion zone |
| title_sort |
system for sorting radioactive waste of the chernobyl exclusion zone |
| author |
Slabospitzkij, R.P. Ganenko, V.B. Bukov, V.T. Savchuk, O.G. Selukova, V.V. Batij, V.G. Kouzmenko, V.O. Stoyanov, V.I. |
| author_facet |
Slabospitzkij, R.P. Ganenko, V.B. Bukov, V.T. Savchuk, O.G. Selukova, V.V. Batij, V.G. Kouzmenko, V.O. Stoyanov, V.I. |
| topic |
Application of the nuclear methods |
| topic_facet |
Application of the nuclear methods |
| publishDate |
2001 |
| language |
English |
| container_title |
Вопросы атомной науки и техники |
| publisher |
Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| format |
Article |
| title_alt |
Система сортировки радиоактивных отходов чернобыльской зоны отчуждения |
| description |
This work is extending the research started in 1998, which are directed on development of a Chernobyl origin radioactive waste sorting system. In this paper the principal scheme and possible engineering solutions of the system for sorting the waste placed in temporary localization dumps of the Chernobyl Exclusion Zone are described.
|
| issn |
1562-6016 |
| url |
https://nasplib.isofts.kiev.ua/handle/123456789/78515 |
| citation_txt |
A system for sorting radioactive waste of the Chernobyl exclusion zone / R.P. Slabospitzkij, V.B. Ganenko, V.T. Bukov, O.G. Savchuk, V.V. Selukova, V.G. Batij, V.O. Kouzmenko, V.I. Stoyanov // Вопросы атомной науки и техники. — 2001. — № 1. — С. 73-80. — Бібліогр.: 15 назв. — англ. |
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A P P L I C A T I O N O F T H E N U C L E A R M E T H O D S
A SYSTEM FOR SORTING RADIOACTIVE WASTE
OF THE CHERNOBYL EXCLUSION ZONE
R.P. Slabospitzkij, V.B. Ganenko, V.T. Bukov, O.G. Savchuk, V.V. Selyukova
NSC KIPT, Kharkov
V.G. Batij, V.O. Kouzmenko, V.I. Stoyanov
ISTC “Shelter”, Chernobyl
This work is extending the research started in 1998, which are directed on development of a Chernobyl origin
radioactive waste sorting system. In this paper the principal scheme and possible engineering solutions of the system
for sorting the waste placed in temporary localization dumps of the Chernobyl Exclusion Zone are described.
PACS:28.41.Kw.
1. INTRODUCTION
In works [1,2] the problems of sorting the solid
radioactive waste (RW) were considered and the
scheme of sorting the Chernobyl origin RW by physical
features, activities and lifetime was proposed. Urgency
of these researches are caused by the fact that now in
Ukraine so large amount of the RW are accumulated
that the necessity of its centralized collection and
disposal has come to a head. It is concerned both to the
RW that have aroused owing to the accident at the
Chernobyl Nuclear Power Plant (ChNPP) and to those
that are constantly produced as a result of activity of
atomic power stations and other objects of nuclear
industry, scientific and medical establishments. The
structure and amount of the solid RW of Ukraine are
presented in Table 1 [3].
At the present time the particular attention is focused
on the RW, which are located in the Chernobyl
Exclusion Zone (ChEZ). There in the object "Shelter",
ChNPP industrial site, stations of temporary localization
of RW (STLRW) and stations of RW storage (SSRW)
(objects of the state plant ”Complex”) accumulated are
∼2.4x106 m3 of radioactive materials [3] of different
activity groups and of a very broad nomenclature. These
RW, consisting 98.6% of solid RW of Ukraine, in many
cases are placed under conditions not adapted for long-
term storage. Inspections of some STLRW have shown
[4], that their design and RW storage conditions do not
satisfy the requirements of the normative documents
regulating RW management in Ukraine. The RW are
placed in STLRW without screening from atmospheric
precipitation and ground waters. Some of them (e.g.
"Neftebaza") are flooded by ground waters so they are
uncontrollable radionuclide suppliers to environment.
Such huge badly controlled amounts of RW produce
potential danger and require a urgent way for
transformation them into a reliably controlled safety
state. The ways of solution this problem are designed in
the Complex Program of RW Management [5].
According to the Complex Program it is planned to
realize the technical design and construction of a RW
treatment and disposal center (TDC), with storehouses
of low and intermediate activity waste [6]. Also, it is
planned to perform a gradual dismantling of STLRW,
extraction and moving of waste concentrated in them
into TDC storehouses. Therewith, according to the
developed scheme of management with RW at TDC [6],
RW will be taken for storage in a selected state. The
sorting must be done by physical features (pressed,
burned, metal, waste non-requiring treatment), activity
groups (high (HLW), intermediate (ILW) and low
(LLW) active waste) and by their lifetime (long lived
(LL) and short lived (SL) radioactive waste). The
process of sorting is strongly complicated owing to a
broad and non-standard nomenclature of the RW, which
are in ChEZ. The developed detailed strategy of
management with such RW is not produced yet. In this
paper one of the possible variants for solving a part of
this large problem is considered.
2. CHARACTERIZATION OF THE RW OF
THE CHERNOBYL EXCLUSION ZONE
RW of ChEZ have arisen due to the accident at
ChNPP-4 Unit and so by their characteristics (relative
nuclide mixture and nomenclature) they are waste of
nuclear power. Therefore management with such RW
Table 1. Solid RW of Ukraine (m3) [3].
Supplier of RW
Waste groups
1
(LLW)
2
(ILW)
Including
Burn Pressed Non treat Metal
Total Fractio
n (%)
NPP of Ukraine 26856 1497 4021 7369 10287 5179 28353 1.2
UkrSP “Radon” 4731 - - - - 4731 0.2
ChEZ:
SP “Complex”
Object “Shelter”
2384000 - - - - 2384000 98.6
1980000 400000 30000 1550000 - 1980000 81.9
345700 58300 160 4840 340700 - 404000 16.7
Total 404181 42209 1900987 5179 2417084
should be regulated by the normative documents
adopted in this branch one of which is a document [7].
Pursuant to this one, firstly, solid waste are active if
they satisfy one of the criteria listed in Table 2,
PROBLEMS OF ATOMIC SCIENCE AND TECHNOLOGY. 2001, № 1.
Series: Nuclear Physics Investigations (37), p. 73-80.
73
secondly, by activity RW are divided on three groups:
HLW, ILW, LLW.
At present, the main sites of RW accumulation in
ChEZ are: object "Shelter", ChNPP industrial site, nine
STLRW, three SSRW and some sites, which are not
registered as temporary or constant dumps. The study of
some of ChEZ RW dumps was undertaken within the
framework of some Ukraine and international projects
(see [8] and refs.).
Analysis results of the research performed before
1998 are submitted in the final report on inventory RW
of ChEZ [9] where data about the volume, weight and
activity of main accumulations of RW in ChEZ are
presented. Accordingly to [9], RW in STLRW are
placed in trenches (≥498) and mounds (≥15). The total
area of STLRW is of about 7.97 km2. The size of
explored trenches widely varying: length from 7 to
315 m, width from 5 to 75 m and depth from 0.5 to
3.7 m. Thus, the RW volume in trenches can change
from tens to tens of thousands of cubic meters. RW
accumulated in STLRW differ by the structure very
much. They include trees, metal, metal designs, stones,
concrete, ground, sand, petroleum, building scraps,
machines. Also, there is a probability of existing small
amounts of special fissile materials (SFM). In some
STLRW predominating is one kind of RW. So, in the
STLRW “Sand Plateau” sand and ground, in the "Red
Forest" trees, bushes, ground, in the "Strojbaza"
concrete, steel designs predominate.
According to estimation [9] the total waste volume
in STLRW is of about 4.69x106 m3 (~2.8x106 tons),
their total activity ~1.9x1015 Bq, average specific
activity ~500 Bq/cm3 (~700 Bq/g). Thus, RW
accumulated in STLRW are the RW of the 1-st and 2-
nd groups. The RW volume in SSRW ("Podlesny",
"Kompleksny", "Buryakovka") is ~5.7x105 m3
(~3.7x105 tons) with a total activity of ~5.5x1015 Bq
[9]. Their average specific activity is ~15000 Bq/g,
thus the waste, disposed at these sites are the RW of
the 1-st, 2-nd and 3-rd groups.
As follows from report [9] ~90% of RW are in
STLRW that agrees with the data of Table 1 (~82%).
They produce ~25% of all ChEZ RW activity (except
RW of the object "Shelter"). But estimations of the total
RW volume in ChEZ given in [9] are nearly as twice
more than in [3]. This difference may be due to the
difference in methods of RW estimation on the one
hand, and reflects a lack of knowledge that compels to
resort to different and rough extrapolations, on the other
hand. Therefore the results of [9] can be considered as
an upper limit of RW amount and can be used for policy
making of RW management. Some results of the
analysis from [9] are shown in Table 3.
This is a special question about possible absence of
HLW in STLRW. Such conclusion (and also
evaluations of volume, structure, specific activity of
RW, which were widely used in [9]) was made on the
base of data obtained during investigations of some
STLRW by the method of γ-probing [10]. According to
this method, downhole measurements of the exposure
dose rate (EDR) in volume of a trench containing RW
using a special probe have been carried out. The
sounding was performed on the grid (5х5, 2х2 or
2х1 m) in depth up to 3 m. In each point EDR was
measured by steps of 0.2 m from the surface and up to
the bottom.
To evaluate the reliability of this method for
revealing small active fragments (some cm), which can
accidentally fall into the RW and lie down separately,
the mathematical simulation was carried out [8] in
geometry of γ sounding used in [10]. The simulation
was executed with the help of the program complex
CYCLONE [1] based on using the Monte-Carlo
method. The spectra of γ-rays in places of the detector
position for fragment of activity 0.001 mSv/h,
0.3 mSv/h, 10 mSv/h (lower limit of LLW, ILW, HLW,
respectively) were calculated. It was supposed that the
fragment is in ground (sand) on different distances from
the point of detecting.
The calculation has shown that the method of γ-
sounding practically can not warrant HLW revealing in
trenches with RW even if the grid step is 1 m due to the
background from surrounding LLW and ILW and also
because of errors of measuring instruments (∼20%).
Thus it is impossible to be sure, that during extraction of
RW from trenches (for which the method of γ- sounding
has shown the absence of highly active fragments) only
LLW, ILW and the waste, which are exempted of
control, will arrive for sorting [8]. Such chance should
be taken into account when designing the sorting
system.
Table 2. Classification of solid RW by the group activity [7]. EDR is the exposure dose rate
№ Dimensions Type of
activity
Waste groups
Exempt of
control 1 group (LLW) 2 group (ILW) 3 group (HLW)
1 EDR, mSv/h. γ <1⋅10-3 1⋅10-3−0,3 0.3–10 >10
2 Volume activity, Bq/kg
β <7.4⋅104 7.4⋅104−3,7⋅106 3.7⋅106−3,7⋅109 >3.7⋅109
α <7.4⋅103 7.4⋅103−3,7⋅105 3,7⋅105−3,7⋅108 >3.7⋅108
3 Surface contamination
activity, particle/(cm2⋅min.)
β <500 500–1⋅104 1⋅104–1⋅107 >1⋅107
α <5 5–1⋅103 1⋅103–1⋅106 >1⋅106
Some conclusions following from the above should
be kept in mind on elaborating the scheme of sorting the
RW, which will be extracted from STLRW.
1) The large volumes of RW and distribution of
dumps on the vast space require that the sorting system
was highly producing and mobile. The probable
availability of a suitable amount of the RW, which are
removed from the control, causes utility to place the
sorting system near the places of RW extraction for
decreasing the cost of their transportation.
74
2) At present only a part of dumps in ChEZ are
investigated in details. In the majority of works the data
about the waste physical characteristics are submitted
very commonly, a significant part of the information is
based on approximated and estimated data and does not
reflect the actual situation and has numerous errors.
Such a situation requires an additional research to
specify the dumps, determine the RW physical structure
and select the most effective sorting methods providing
necessary treatment and management of RW.
3) Information about the waste α activity in many
cases is not submitted. However, for many dumps (if
not for all) it is necessary to take into consideration a
probable availability of a significant amount of
transuranium radionuclides or high active fragments.
Uncertainty of RW nuclide composition causes
necessity of additional control, necessity to have a more
broad set of sorting schemes, that complicates and rise
the price of a system.
4) Very large oscillations of the RW activity from
HLW which are exempted of control, wide scattering by
physical features, forms, sizes, humidity complicate the
selection of the most effective and economic methods of
sorting which besides would allow to automate the
process. These circumstances do economically
unprofitable creation of a universal system, which
would be applied for all possible conditions.
3. SPECIALITIES OF THE RW ChEZ
SORTING BY ACTIVITY AND LIFETIME
Existing national and international classifications
and technology of management with RW allow one to
classify ChEZ RW depending on:
- level of activity and degree of contamination by
groups LLW, ILW and HLW;
- time of exemption of control- by SL and LL waste;
- contents of SFM;
- physical features- by liquid and solid;
- physical-chemical characteristics.
The sorting system must segregate RW according to
the adopted classification. As was mentioned above the
RW of ChEZ under their characteristics are waste of
nuclear power, therefore their segregation by activity
groups (LLW, ILW, HLW) should be regulated
accordingly to criteria listed in Table 2. Their
classification by lifetime is regulated by the law- "The
management with radioactive waste". In accordance
with this law the long -lived waste (LL) belong to the
RW exemption of control which is achieved in three
hundreds or more years. This waste must be disposed in
stable geological formations.
A direct determination of the nuclear composition of
RW and the partial activity of nuclides, especially, α
active ones, with the purpose of determining their
lifetime is a very difficult task. However, Chernobyl
origin of RW allows to essentially simplify the process
of RW sorting by lifetime. As is well known, the RW of
ChEZ arose owing to expansion of radionuclides, which
were accumulated in the nuclear fuel of the working
reactor into the environment as a result of the accident.
The average fuel radionuclide composition in 2000 year,
which is determined by conditions of the reactor work,
is listed in Table 4 [11], where the expected activity (A)
of these radionuclides calculated for 2300 year is also
listed. One can see that at present more then 90% of the
Chernobyl origin RW activity is caused by the 137Cs but
after 300 years the activity of these RW will be
determined by the α-activity of transuranic
radioisotopes. The criteria of RW decontrol are the
values of activity listed in Table 2. For α-active
radionuclides this criterion is equal to 7.4 Bq/g of the
specific activity. After 300 years the α activity of the
waste will decrease approximately on 8%. Therefore to
decontrol the Chernobyl origin RW in 2300, it is
necessary that in 2000 year the specific α activity of this
waste would be of about 8 Bq/g. Waste with α activity
exceeding this value must be referred to the LL
category.
In 2000 year the value of 137Cs specific activity,
corresponding to the criterion determined by the
Ukraine law for the lower limit of volumetric α- activity
of LLW is ∼220 Bq/g for ChEZ RW with the average
fuel concentration. Then by measuring the specific
activity of 137Cs in 2000 it is possible to make
evaluations of RW nuclide composition, if the relative
contents of radionuclides (correlation relations) and the
concentration of fuel in waste are known. Accuracy of
these evaluations depends on errors with which the
correlation relations of a given accumulation are
determined. It should be noted that in accordance with
the IAEA recommendations, [12], for definition of the
level of LL waste one uses
Table 3. Volume, mass, activity of RW from the
Chernobyl Exclusive Zone located in stations of
temporary RW localization (STLRW) and stations of
RW storage (SSRW) [9]
STLRW and
SSRW
Vol.
(m3)
Mass
(ton)
Activity
(Ci)
Strojbaza 398000 539000 35583
Red Forest 250000 400000 8400
Yanov Station 18686 29897 78
Neftebaza 122118 192705 1494
Sand Plateau 100000 180000 5000
Purifying build. 200 200 1
Pripyat 16000 11000 700
Chistogalovka 160000 150000 100
Kopachi 110000 390000 900
Living house 2900000 880000 200
Podlesny 11000 22000 70000
Kompleksny 26196 41914 12727
Buryakovka 533574 825560 65596
criterion of the waste specific α-ctivity in 400 Bq/g for
one package. This results in that the level of a specific
137Cs activity for the lower limit of LL waste equals to
1.1x104 Bq/g in 2000 year for the average fuel
composition of ChEZ RW.
There is a very large volume of RW in the ChEZ
therefore it is necessary to construct a productive sorting
system for RW processing. A key problem for solving
this problem is the choice of a method, which allows
obtaining a high sorting output. As follows from the
above there is a relation between the activity of the
Chernobyl origin RW, which is caused mainly by 137Cs
and the classification of these RW by lifetime, which is
determined by α-active radionuclides. (The same
relation is also between EDR, which is created by RW
75
loaded in the container fixed by the form and volume
and RW lifetime). This relation can be used for sorting
and then the 1-st criterion of Table 2 must be used. To
apply this, the EDR at the distance 0.1 m from the
surface of the package with RW must be measured. In
the present time 137Cs is the most promising
radionuclide for practical determination of the RW
category, because it has the characteristics convenient
for EDR measurements, and produces 90% of RW
activity.
We performed calculations of EDR created by
containers of various volumes with RW having the
specific activity of 137Cs 1000 Bq/g at a distance of
0.1 m from their surface, Fig. 1. The calculations were
made by the Monte Carlo method with using the
program complex CYCLONE [1]. The EDR value is
equal to 9.6×10-2 mSv/h for 200 l packages (which are
widely used in the world practice, especially for LL and
HLW) and for the given specific activity. If one uses the
calculated value of specific 137Cs activity corresponding
to the LL waste criterion under the Ukraine laws
(220 Bq/g) it is possible to evaluate EDR from such a
package when LL is placed in it. For 2000 year this
limit EDR value equals 2.1×10-2 mSv/h. Using the same
approach for the criterion recommended by IAEA (1.1×
104 Bq/g) we shall get a value of ~1.1 mSv/h.
Analyzing the results obtained and comparing them
to criteria listed in Table 2, one can to conclusion that,
according the Ukrainian laws being in force now (under
condition of loading in 200 l packages) the most part of
Table 4
Isotope Type of
radiation Т1/2, years А, MBq/g UO2,
Years − − 2000 2300
90Sr β 28.6 850 0,6
106Ru β, γ 1.057 0.46 -
134Cs β, γ 2.06 8.0 -
137Cs β, γ 30.17 1015 1,0
144Ce β, γ 0.779 0.08 -
154Eu β, γ 8.8 24 -
238Pu α 86.4 6.1 0,5
239Pu α 24110 5.0 5,0
240Pu α 6553 8.2 7,9
241Pu β 14.4 490 2,6⋅10-4
241Am α, γ 432.5 16.4 20,5
244Cm α 18.11 1.3 -
LLW, and of all ILW and HLW should be referred to
LL. Fig. 2 shows the correlation between the RW
classification by activity (and lifetime) and the fuel
concentration, which unambiguously determines the
level of Chernobyl origin waste activity. In the case of
transition to the specifications recommended by IAEA
only a part of ILW and all HLW should be referred to
LL waste that is in 10-100 times less.
As follows from the above due to the relation
between the activity and lifetime the most promising
method for RW sorting is the method of passive gamma
analysis based on EDR measurement of waste γ-
radiation and the using of the correlation relations
between isotopes which are in RW ChEZ. This method
is cheap and rather fast, because the waste activity
group and the lifetime are determined simultaneously in
one measurement and the intensity of the RW γ
radiation is rather high. It does not require large and
expensive arrangement. The accuracy of the method
depends on the accuracy of EDR measurement and
errors with which the correlation relations are known for
the RW accumulation.
It should be noted that cesium has a high mobility,
which depends on temperature conditions. So, those
materials, which in the greater degree undergone to the
temperature influence, have lower cesium content while
the samples taken further of the accident place contain a
higher quantity of cesium, than it would be possible to
expect. Therefore divergence in the relative activity of
nuclides (correlation relations) for different tests of the
RW is observed. However, one can use the average
values of correlation relations, which in accordance with
data of [13] within a factor of 2, coincide with real ones
independently from the place of RW location. This
conclusion is confirmed by results of the research at the
industrial site of the object "Shelter" [14] and in ChEZ
[10]. The average values of correlation relations
obtained by different organizations are rather close [11]
that justify a possibility of using such data with an error
of 30-40%.
Proceeding from the results of EDR measurement
performed at a distance of 0.1 m from the surface of a
200 l package with RW, the values of correlation
relations of which corresponds to the average fuel
composition, one can determine the radionuclide
activities in these wastes.
10 100 1000
0,04
0,06
0,08
0,10
0,12
D
R
, m
S
v/
h
V, m3
Fig. 1. The EDR at 0.1 m distance from the surface
of package with RW having specific activity 137Cs
1000 Bq/g as a function of package volume
1E-9 1E-8 1E-7 1E-6 1E-5 1E-4 1E-3 0,01 0,1 1 10 100
1E-9 1E-8 1E-7 1E-6 1E-5 1E-4 1E-3 0,01 0,1 1 10 100
C,%
LLW ILW HLW
SL CL LL
Fig. 2. Connection RW classifications and
concentration of fuel in waste
4. SCHEME OF SORTING ChEZ RW
76
Results of the analysis of dumped RW displacement
waste nomenclature and expected activity, results of the
simulation of sorting ways and techniques are used as a
basis for elaboration of the principal scheme of sorting
RW located in STLRW. As follows from the above, the
system assumes the sorting of RW extracted from
STLRW in two stages.
1. The main sorting of RW is made near STLRW.
2. The additional sorting is made in TDC after RW
processing and, in the case of necessity to sort LL
waste, it is done with the use of active neutron analysis.
The advantage of RW sorting near STLRW is
caused by such reasons:
- RW should come to TDC in a sorted kind;
- sorting near the place of extraction reduces the
amount of RW which goes to TDC, because at once one
separates and direct into the dump the waste which are
exempted of the control;
- mixing of HLW and LL with the waste of other
activity groups is not admitted, due to their separation at
stage 1 of sorting.
In Fig. 3 the block scheme of the system for sorting
RW (by physical features and activity), which are
located in STLRW, is shown (dark color marks
technological operations which do not concern to the
system).
At the first stage the RW are sorted by:
a) activity groups and time of decontrol- into LLW,
ILW, SL waste, waste which are exempted of control,
HLW and LL waste;
b) physical features- into RW in the bulk-form
(ground, sand, road metal, small pieces of metal, tree
etc.) and RW in the object form (metal designs,
machines and gears, bulky concrete units, trees, etc.).
Partially, the sorting can be produced already during
RW extraction from STLRW, and this should be
provided when designing the RW extraction system.
Though a noticeable amount of HLW in STLRW is not
expected, however it is necessary already at preliminary
sorting to carry out the control for probable appearance
of HLW in the radioactive waste and their separation.
As was shown in [8], it is impossible to find active
fragments in trench with RW, and unambiguous
identifying HLW in the dredge ladle during their
extraction also is not always possible. Thus under the
data of a mathematical simulation the scheme of the
management with RW, which are extracted from
STLRW, should take into account possible appearance
of high active fragments and the sorting should be made
using techniques allowing to reveal and to sort out
HLW. The further operations with HLW are conducted
in accordance to the plan of management with waste of
this group, (see, e.g. [1,2]) and here are not considered
in details. However, since their amount in STLRW is
expected to be small, their processing and detailed
sorting should not be performed near the place of
extraction, but at the special place and with special
equipment in TDC.
Other RW are divided into the waste in the object
form and in the bulk-form. RW in the bulk-form, if
necessary, are processed to required size (some cm) and
are sorted by features of required processing. Necessity
of processing RW in the bulk-form can arise when on
sorting waste of mainly one type (metal or those, which
are burned) is arrived. These RW are loaded in 200 l
packages and transported in TDC.
The RW in the bulk-form which do not require the
processing, go onto the conveyor for sorting by activity,
where their separation into groups and categories of
activity, time of exemption of control is performed with
the use of the passive gamma-method and correlation
relations. Simultaneously the total weight of RW after
conveyor sorting is determined. Proceeding from the
volumes of RW to be sorted, the efficiency of the
conveyor system should be no less than 4 m3/h. After
sorting, RW exempted of control are directed in dumps,
and SL and LLW are loaded in suitable containers and
are transported to TDC. The LL waste is loaded in 200 l
packages accordingly with the scheme of management
with RW.
RW in the object form are, as a rule, surface-
contaminated constructions or gears. After
determination of level of their contamination the
materials exempted from the control are directed in
dumps, and others are divided in those, which require or
do not require processing, and then are transported in
TDC.
The processes of containerization and transporting
do not concern to the system of sorting and are not
considered in details.
At the second stage of sorting after RW arriving into
TDC, the kind of processing is determined for those
one, which require treatment. The treatment (burning,
pressing etc.) decreases the RW volume. Before
treatment RW, which are in the bulk-form are certified
with the purpose of determining their element
composition and activity. After treatment RW will be
undergo to the additional control because in the result of
processing and compacting the transition of these RW in
other group (HLW or LL) is possible. The sorting
system must separate such waste by activity into groups
LLW, ILW, HLW and by lifetime into conditionally LL
(CLL) and purely LL waste with the purpose of separate
storage of CLL (CLL are waste, which
77
Fig. 3. Structure of the sorting scheme RW of Chernobyl Exclusive Zone on physics features and activity
RW STLRW RW accumulations that
do not requre obligatory
extractionRW accumulations that are
extracted
RW in bulk-form Large-size RW (in obgective form)
RW treatment
Sorting on activity
Dumps Storage for SL waste Storage for conditionally LL waste Storage for LL waste
Transport to TDC
Determination of level surface contamination and local
dissemination of activity
Sorting by activity in 200 l packages
SL waste in large-size
conteiners
LL waste in 200 l
packages
RW that are exempted of
control
RW that requre
treatment (wood, metal) RW that do not
processing
Sorting LL waste by active neutron
method
TDC
Transport to TDC
RW that do not requre
treatment
RW that are processed in
200 l packages
Transport to TDC Transport to TDC Transport to TDC
Certification
RW that are exempted of
control
Transport to dumps
Transport to dumps
HLW
Stage II
Stage I
belong to LL grope only according to the Ukrainian low
and are not LL according to norms recommended by
IAEA). Such approach, in view of the expected
transition of the Ukraine legislation to the international
standards, enables one to transfer storehouses of CLL
into subsurface disposals without repeated sorting and
large economic expenses. The RW sorting in TDC is
supposed to be carried out in standard 200 l packages,
with using, if necessary, the active neutron method for
determination of SFM availability. RW in the object
form and the containers with RW, which do not require
treatment, as well as the containers with the processed
RW are transported to the storehouses specified for
definite groups and categories of waste.
5. ENGINEERING SOLUTIONS OF MAIN
UNITS OF SORTING SYSTEM
In accordance to the submitted block scheme two
basic systems are engaged for sorting: the system of
conveyor sorting of RW in the bulk-form and the
system of sorting the waste in 200 l packages.
Conveyor sorting RW in the bulk-form. The system
of conveyor sorting RW in the bulk-form by activity is
placed near the site of RW extraction from STLRW and
is aimed on express waste sorting into groups LLW,
ILW, waste exempted of the control, and category SL
and LL waste. Also, the separation of HLW will be
produced if they fall into the RW that are extracted.
Simultaneously with the determination of groups and
categories of activity the system determines the total
weight of the RW, which have passed conveyor sorting.
RW sorting is based on the method of passive gamma
analysis considered above.
The sorting system includes a subsystem for forming
portions of RW for analysis, conveyor line, measuring
facility and sorting arrangement. If necessary the
radioactive waste before sorting are treated to obtain a
required size of pieces (no more than 5 cm). The
volume of the RW portion entering for passive γ
analysis is of about 0.04 m3 (10x50x80 cm3). The
distance between RW portions on the conveyer is of
about 50 cm. It is chosen of necessity for the system
productivity and task of decreasing the measurement
error.
A measurement facility is destined for EDR
measurements of RW portions. As detectors for this
facility one can use detectors on the base of NaJ or CsJ
crystals. To estimate time required for measurements
with this arrangement we have carried out the
simulation of this process with the NaJ detector
(4x4 cm) placed at a distance 10 cm from the surface of
RW. It has been found that the minimal time required
for getting necessary number of counts (no less than
100) for RW belonging to HLW, ILW, LLW groups is
5х10-7, 5х10-4, 2,5х10-2 s, respectively. For detector with
the crystal sizes of 1,13х1 cm these times are 10-5, 10-2,
5х10-1 s. From results obtained it follows that the sorting
productivity will depend, first of all, on the speed of
conveyor movement but not on the time of measurement
of RW portion activity. If productivity of the conveyer
is planned to be not less than 4 m3/h it means that the
conveyer must pass up to 100 portions with RW per
hour. If the distance between them is 50 cm, one portion
will be under processing during ~18 s. To obtain such a
high productivity of the conveyor its construction
should be designed with high technical requirements
and conditions.
The calculations, which have been made for
detectors (with NaJ crystals volume of 1 cm3), placed at
the distance of 1 m from RW surface, have shown that
the statistical errors of EDR measurements during
processing time is no more than 7% for measurements
at the lower limit of LLW. The calculations show also
that the detection device will work with a great loading.
To decrease the load the detectors should be shifted at a
distance providing necessary loading. Besides, one
should use fast electronics.
After sorting RW by activity they are delivered to
suitable transport channels with subsequent loading into
transport containers of a suitable type.
The system of RW sorting by activity in 200 l
packages. The system of RW sorting by activity in 200 l
packages is placed in a technological building of TDC
where separation of RW into groups HLW, ILW, LLW
and categories SL, LL and CLL is executed. It is
planned to use this system in such cases:
-more precise determination, if necessary, of LL
activity waste in the bulk-form, which do not require
processing and arrived to TDC in 200 l packages after
preliminary conveyor sorting on place of extraction,
with the purpose of separating them into CLL and LL.
These RW are arrived on the control in a fragmented
form and are sorted by physical properties;
-sorting RW by activity and lifetime after treatment
in TDC and, consequently, possible transition them into
others groups (HLW or LL waste). In this case it is
supposed to carry out the control of SDM presence in
such RW with using active neutron analysis.
The system operates with standard 200 l containers
KSTA-02 developed by STC CMRW [15]. It includes a
transport subsystem (conveyer line) and a measuring
subsystem. The conveyer line is made on the base of a
roller conveyer and is used for transport of packages
with RW up to 400 kg weight into a measurement
facility. After measuring the weight and activity of RW
they are transported to other sites. Containers have
marks necessary for automatic information processing
and tracking.
The RW enters onto the control in 200 l containers
in the fragmented form and sorted by physical
properties and with a known weight. As it has been
shown by simulation, to inspect the most part of
container volume with using the passive γ-method it is
necessary to scan the container. A maximum rotation
rate of the container at scanning is of about 1 turnover
in minute.
The EDR measurements are made in the range of
activity from 0.1 mkSv/h to 1 Sv/h for RW with a
maximal specific activity of ∼100 MBq/g. The
preliminary calculations show, that the necessary
number of detectors is of about 5. They may be
produced on the base of NaJ, CsJ or BGO crystals. The
detectors are placed into the lead shield and equipped
with collimators. They have such sizes that the
container KSTA-02 can be scanned during one rotation
that essentially accelerates the measuring.
The expected values of detector counting rates were
got by simulation of the γ radiation spectrum, which is
radiated from the given container with RW of definite
groups and which is produced by 137Cs. It is supposed
that 137Cs are uniformly distributed in the container
volume in a substance with an average density of
2 g/cm3 and average atomic number Z=14 (sand).
Results of the counting rate calculations for one of
the possible variants of the measuring system placement
are shown in Table 5. In this variant the detectors are
placed behind the 30 cm long collimators, the front edge
of which is at a distance of 10 cm from the container
surface. The dimensions of the collimator hole are
10x1 cm. The detector registration efficiency is
supposed to be 100%. The calculations have shown that
the scattered γ quanta increase the loading of detectors
in 3 times. The counting rate may control by changing
the distance between the detectors and container or
collimator hole. The time required for obtaining the
minimal necessary statistics (∼100 counts) is no more
than 10 s.
0 2 4 6 8 10 12 14 16 18
0,20
0,25
0,30
0,35
0,40
0,45
0,50
S
fp
/S
co
m
p
Distance from surface, cm
Fig. 4. Ratio of the fotopeak and the total γ spectrum
areas as a function of depth of active fragment
localization from side face of cylindrical container
Table 5. Flux of γ-quanta from the 200 l cylindrical
container with RW at a distance of 10 cm from the side face
C-ng rate, s−1 RW groups
LLW ILW HLW
Photopeak 11-1100 1100-
38000 ≥3.8×104
Total 33-3300 3300-
110000 ≥1.1×105
A photopeak proportion in the total counting rate
output decreases with the depth position of the active
layer, Fig. 4. So, the control of high-activity small
fragments, which can exist in the package, by the
passive γ- method will be effective up to depth of ∼
15 cm from the package surface. In the case of the
container KSTA-02 it consists ∼85% of the volume. For
uniform distribution of RW in the container and their
density ≤2 g/cm3, a possible error of evaluation by the
total 137CsЈ activity is expected no more than 20%.
This system operates in the automatic mode. The
maximum output is up to 10 containers in hour (2 m3).
More detail engineering solutions concerning these
systems are considered in [8].
REFERENCES
1. V.G. Batij, V.P. Bozhko, V.B. Ganenko et al.
System of waste sorting by physical features and
activities. Preprint NNC KFTI 2000-1, Kharkov,
2000.
2. V.G. Batij, V.P. Bozhko, V.B. Ganenko et al.
Design of the system for RW sorting by physical
features and activities. Final report SDR NSC KIPT,
№ 0198U007630, 1998.
3. S.G. Pechurin, A.D. Novikov, S.G. Tanskii. Some
thoughts about ways of realization of Complex
program management with radioactive waste in
Ukraine // Atom. Energ. ta prom. Ukraine. 1999, №2,
p. 14.
4. A.I. Ledenev, P.A. Ovcharov, I.B. Mishunina,
V.M. Antropov. Results of the complex radiation
state investigations of the station of temporary
radioactive waste localization in Exclusion Zone of
ChNPP. Problems of Chernobyl Exclusion Zone.
1995, v. 2, p. 46.
5. Complex program of radioactive waste
management. Decision CMU, № 542, 1999.
6. Design of the first line of the plants for radioactive
waste deactivation, transport, processing and
disposal from territory contaminated in result of the
accident on Chernobyl AES. Etap 1. Radioactive
waste disposal. Start complex. NTC CMRW. Yellow
Water. 1998.
7. Sanitary rules of design and operation at the atomic
station. SRAS-88. PNAE. 1988.
8. V.G. Batij, V.P. Bukov, V.B. Ganenko et al. Design
of RW sorting system and design of technical
solution of subsystems for sorting RW by physical
features and activities. Report SDR NNC KFTI,
№ 01990002588, 1999.
9. Final report on the inventory RW of Chernobyl Exclusion
Zone. Report OSAT/RPT/OS/00031. Brussel, 1999.
10.Radiation investigation of STLRW “Sand Plateau”
and analysis of the dumps influence on environment.
Report on 5-th stage of the work № 13/111 Н-98.
State Registration № 01984003952. NTC CMRW,
Yellow Water, 1998.
11.Analysis of the current safety of the object
“Shelter” and prognosis estimation of situation
evolution. PO “Chernobyl AES”. 1996, 188 p.,
Chernobyl.
12. Classification of Radioactive Waste. A Safety
Guide. Safety series № 111-G-1.1. IAEA. Vienna, 1994.
13.Obtaining experimental data for determining the
present-day status of dust contamination and
carrying out quantitative estimations consequences
of radiation accident on the object “Shelter”. Report
MNTC by 1-st stage work 78/96. Chernobyl, 1997.
14.Characterization of radioactive waste located at the
"Shelter" industrial site. Project B7-
5200/97/000077/MAR/C3. The report: Task 1.
Inventory, generalization and analysis of data about
kinds and volumes of radioactive materials,
concentrated at the "Shelter" industrial site.
Chernobyl. 1988.
15.O.M. Bogachev, G.A. Ermolin. On classification of
radioactive waste. Problems of Chernobyl Exclusion
Zone. 1995, v. 2, p. 10.
1. INTRODUCTION
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