Current State of «Shelter» Object
Oleksandr KLYUCHNYKOVThe Interdisciplinary Scientific & Technical Center “Shelter”
36-a, Kirova st., Chornobyl, Ukraine
INTRODUCTIONOn April 26, 1986, the biggest accident in power engineering history took place at the ChNPP Unit 4,
which resulted in total destruction of reactor core, damage of reactor department, deaerating stack, turbinehall (TH) and a range of other buildings. Barriers and safety systems, which were protecting theenvironment from radionuclides contained within the irradiated fuel, were destroyed, and the activity was
released from reactor. That release, being of some million curies per day, was occurring in the course of
10 days, from 26.04.86 to 06.05.86, thereafter it dropped at some thousand fold, and subsequently, wasgradually reducing (Fig. 1).
The main «Shelter»’s peculiarity is its remaining potential danger, much more greater, that is
accepted by the norms and rules existing for the objects, that contain nuclear hazardous fissile andradioactive materials.
As a whole, in the view of radiation safety, the «Shelter» object is an opened source of alpha-,beta-, gamma- and neutron radiation, which with its radiation characteristics has no analogues in worldpractices
Definition of «Shelter» object’s current status is described in the addendum to NRBU-97«Radiation protection from potential exposure sources» (NRBU-97/D-2000).

Release intensity
MCi/day

0.05-0.15 MCi/day

April

May

Figure 1 – Intensity of fission product release of reactor core (the first 10 days)- 20 -

It reads: «…»Shelter» object in its today conditions should be classified as «the place forsurface storage of unorganized RAW («temporary repository of unorganized RAW being in stage ofstabilization and reconstruction»).
1.

UNIT 4 DESTRUCTIONS AFTER ACCIDENT AND CREATION OF «SHELTER»OBJECT
After the explosion occurred in the 26.04.86 night at ChNPP Unit 4, a part of reactor unit
structures, deaerating stack, turbine hall and other buildings become ruined (Fig.2). The main damages ofbuildings, which it succeeded to detect during the external examination and when penetrating into
accessible (due to radiation level and destruction rate) premises, were as regards:
Reactor unit.
Active core is completely destroyed. Its fragments were thrown out by the explosion into building
breakdown, to the roofs of neighbouring buildings, ventilation pipe sites, scattered along adjoining
territory. It was cleared up later, that a part of nuclear fuel came to bottom marks of reactor department in
the shape of fuel lava.
Upper plate of biological shield (scheme «E») is torn off from its place and is standing inclined
across the reactor vault. Walls and ceilings of reactor Central Hall are destroyed. Ceilings are displaced
and walls of drum-separators’ premises are destroyed. Reloading machine was torn off and came down.
Premises of northern main circulating pumps (MCP) are completely destroyed, premises of southern MCP– are partially destroyed.
Deaerating stack.
Two upper floors are destroyed; framework columns are displaced to turbine hall side.
Turbine hall.
As a result of fire and debris collapse, roofing is destroyed in many places. Air-blast deformed
several building trusses, framework columns along axis A are displaced.

Figure 2 - Destroyed ChNPP Unit 4- 21 -

Unit of reactor department auxiliary systems.
It has several local destructions.
Reactor scram system.
Is completely destroyed and blocked with building structures.
Except the above main destructions, there were numerous destructions of individual structures andpremises, which did not exerted any great influence to general buildings' stability.
Territory.
After the explosion occurred, the territory adjoining directly to destroyed unit was contaminatedby the scattered fragments of active core: fuel rod debris, graphite stack parts, structure elements. Theycame to the roof and inside the turbine hall, deaerating stack, on Unit 3 roof, metallic supports ofventilation pipe, etc.
In the middle of 1986 May, the Government Commission took the decision on long-term
conservation of Unit 4 aimed at prevention of radionuclides release into the environment and reduction ofpenetrating radiation impact at the ChNPP site.
In keeping with the CC CPSU and USSR CM Decree No 634-188 of 29.05.86, the USSR Ministryof medium machine-building was vested with “the works for burial of ChNPP power Unit 4 and related toit buildings”. The facility was called as «the Shelter of ChNPP Unit 4».
1.1. «Shelter» object structure
The erection of «Shelter» was completed in 1986 November.
On November 30, 1986, the State Acceptance Inspection appointed by the USSR Council of
Ministers Decree of October 23, 86, No 2126рс, accepted to the maintenance the ChNPP conservatedpower Unit No 4 (Fig.3, 4).
In turbine hall between the power units, 2.3-m thick cast concrete wall was erected to mark +19,0,
and above – that of 1.4-m thick. In the deaerating stack, partition walls are made of 1-m thick castreinforced concrete along the row along the row Б between the axes 41-35, and along the axis 41 between
the rows Б-В.
In reactor unit, partition wall to mark +12,0 m between the rows Т-Л is made by the way of fillingwith concrete of transport corridor between the axes 41-42. In other places, existing walls and partitions

Figure 4 – A view of «Shelter» object

Figure 3 – Erection of «Shelter» object- 22 -

after appropriate filling up of apertures, openings, cracks, etc., were used.
Along the Unit 4 perimeter, at first «pioneer» protective ferroconcrete walls were made of height:- around 6 mfrom obstruction side (northern unit side);- around 8 mfrom southern and western side.
Northern cascade wall was made of concrete in the shape of around 12-m high projections.
Preserved western wall from the outside is closed with the wall having 50-m high buttresses.
To support the main B1/B2 beams installed along the П and Ж rows, around 0,9-m thick debris offerroconcrete wall at western part were used along axis 50, and ferroconcrete ventilation shafts near theaxes 43-44, which preserved after explosion.
Damaged wall site within the area of row Ж before the beams installation is reinforced by steel
stay with its subsequent concreting.
Over B1/B2 beams, 27 metallic tubes of 1220-m diameter and 34,5-m length are laid, and over the
tubes - the roofing is made of profiled deck – 6 spatial units.
As a support for steel boards in southern side, steel «Mammoth» beam serves, which is installed
along the row В, and which, in its turn, rests upon concrete bearers near the axes 41 and 51.
The bearers were made on an obstruction of destroyed ferroconcrete structures of ceilings of two
upper floors, equipment and pipeline debris.
For the ceiling of unit site between the axes 40-50 in rows Б-В along the row Б supporting on theanother ceiling that was obstructed by destroyed structures, chest beam was designed and manufactured(«Octopus»), which serves as a distributing structure.
Over the turbine hall (TH) in the axes 40-50 between the rows А-Б, a new roofing is designed tobe made of beam-trusses and steel boards resting, along the row A, upon newly installed spatial columns
and preserved cantilevers in columns along the row В. Between the axes 54-50 and 40-34, spatial steel
units on existing coating are laid.
2.
NUCLEARLY HAZARDOUS MATERIALS INSIDE THE «SHELTER» OBJECT(INTEGRAL ESTIMATES)
2.1
Nuclear fuel located inside Unit 4 before the accident
Before the accident, nuclear fuel was located in four places of Unit 4 reactor department:- in active core of RBMK-1000 nuclear reactor;- in pool for exposition of spent fuel cassettes;- at site for preparation of fuel cassettes in Central Hall;- in premises for preparation of fresh fuel.
Distribution of nuclear fuel before the accident is shown in the Table 1.
Table 1 - Location and amount of nuclear fuel in Unit 4 reactor department premises before accident
Premises
Technological assignment of premises
Nuclear fuel amount on uranium, t
504/2
Reactor vault*190.2505/3Southern cassette exposition pool**14.8914/2
Central hall
**5.5
503/2
Premises for fresh fuel preparation**. ***4.1
Total**214.6* - to accident moment, reactor active core contained 1659 fuel assemblies (FA), 1 additional absorber (AA)and one unloaded fuel channel. Major part of FA represented the cassettes of first loading with burnup being 11 15 MWt · day/kg (U). The core also contained some amount of fresh fuel. Uranium mass in each cassette madeup – 0,1147 t. Total mass of fuel loaded in active core, made 190,2 t.
** - data are taken from “Certificate of nuclear fuel amount at Chornobyl NPP Unit 4 at accident moment”,
confirmed by Chief Engineer of IA ChNPP on 30.01.96. Besides, the data on fuel amount in exposition pool aredelivered on the basis of log for registration of NSD and NM, and in Central Hall and premises 503/2 - on thebasis of «Certificate for write-off of fresh nuclear fuel from Unit 4 of 26.04.86».
*** - nuclear fuel from preparation premises (premises 503/2) was removed in 1986 (after accident) to
ChNPP fresh fuel storage.
- 23 -

2.2.
Fuel-containing materials that are currently located in «Shelter» object premises
Currently, inside the «Shelter» object, there are nuclear fuel modifications, which produced in thecourse of proceeding of accident active stage and during interaction of that fuel with structural materials,
dynamic and thermal impact of explosion, as well as during oxidation of uranium dioxide when contactingwith air oxygen before and after the reactor burning.
Such modifications include as follows:
2.2.1. Active core fragments
During the mitigation of accident
aftermath, a part of active core fragments (ACF)
representing fuel pellets, debris of fuel rods, fuelassemblies, graphite, located around the building,
was displaced to the breakdown and thereafter
buried in cascade wall, a part is collected incontainers with high-level waste, another part isburied under the layer of concrete and crushedstone strewn near the Unit. Destroyed fuel that was
released on buildings roofs and pipe sites, wasthrown down in reactor ruins (Fig.5).
Significant ACF amount must be locatedin the CH and premises 305/2.
2.2.2. Lava-like fuel-containing
materials (LFCM)
Lava-like materials containing nuclear fuelwere detected in many subreactor premises (Fig.67). They contained a significant part of uranium
located before the accident in active core, and aconsiderable part of radionuclides, which were
produced in reactor.
LFCM represents a heterogeneous solid
solution, whose «dissolvent» is vitreous silicate
matrix with great amount of diverse impurities,
among which uranium oxides, uranium-zirconiumoxygen phase (so called “chernobylite”), andmetallic globules are encountered.
Uranium percentage within the LFCM
fluctuates within the range from 5 to 10%.

Figure 5 – Premises 305/2. Southeast sector.
Active core fragments

Figure 6 – Lava in steam discharge valve of SDC

2.2.3.

Total amount of nuclear fuel in
different premises of «Shelter»objectIntegral estimate of current nuclear fuelamount in different premises of «Shelter» object
are shown in Table 2.
Figure 7 – Lava in PSP-1- 24 -

Table 2 – Fuel amount estimates in «Shelter» object premises
Name (numbers) ofpremises

FCM
modifications inpremises

Detected fuel,t (U)(estimates for year of 2004)

Central hall
(914/2)

active corefragments

more 21

Southern exposition pool(505/3)All upper premises,
including CH(mark +24.00 and above)
304/3

active corefragments
fuel dust

14.8

LFCM

∼5 on obstruction surface inCH,∼30 total
6±2

301/5+301/6+303/3
217/2

LFCM
LFCM

4.5 ± 2.5
0.4 ± 0.2

Subapparatus 305/2 and504/2 before mark 24m.

fragments of
AC, LFCM,
dust
LFCM
LFCM

85 ± 25

SDC (210/5+210/6+210/7)
PSP-2(012/14+012/15+012/16)
PSP-1(012/5+012/6+012/7)
Fuel under cascade wall
Water in all premises ofreactor department
Fuel at «Shelter» site

LFCM
fragments ofAC, dust
soluble uranium
salts, dredge.
Fragments
AC, dust

12 ± 6minimum - 3,
maximum - 14
1.9 (+1.0; -0.5)

Notes
Considering 48 assemblies withfresh fuel (5.5 t)
Is possible LFCM presence
129 spent fuel cassettes.
Is possible LFCM presence
Estimate 30 t includes surface
contamination inside obstruction
in CH and in all other premises«Horizontal lava flow». FCM are
included in breakdown between
prem.304/3 and 305/2.
«Horizontal lava flow»«Elephant foot», «stalactites».
LFCM came from «horizontal
flow».
Estimates were made for 6 FCM
clusters.
Origin of all LFCM flows.
«Big vertical flow» and «small
vertical flow»?
∼4 kg
0.75 ± 0.25

Specific activity of some emitters for base fuel content of power Unit 4 for 01.02.2005 is shown in
Table 3
Table 3 - Specific activity of some emitters for base content of power Unit 4 fuel at 01.02.2005, Bq/guranium
Alpha-emitters
Beta-emitters
Beta-gamma-emitters6
8
Pu-238 --- 6.7 · 10
Sr-90 --- 7.60 · 10
Rh-106 --- 1.29 · 104
68
Pu-239 --- 5.0 · 10
Y-90 --- 7.60 · 10
Sb-125 --- 7.12 · 105
Pu-240 --- 8.19 · 106
Ru-106 --- 1.29 · 104
Cs-134 --- 1.61 · 1063
7
Pu-241 --- 9.32 · 10
Pm-147 --- 2.65 · 10
Cs-137 --- 9.09 · 10848
Pu-242 --- 1.30 · 10
Pu-241 --- 3.89 · 10
Ce-144 --- 1.20 · 103
7
Am-241 --- 1.95 · 10
Eu-154 --- 1.64 · 107
3
Am-243 --- 8.73 · 10
Eu-155 --- 4.45 · 1066
Cm-244 --- 1,07 · 10
In sum ≈ 80 Ki/kg uraniumThus, total activity of fuel currently located in «Shelter» object makes around 14 MCi.

- 25 -

3. WATER LOCATED IN «SHELTER» OBJECT PREMISESOne of the main sources of radiation hazard in the object is the water. Water influences thenuclear safety conditions, thus leading to change of reproducing system «FCM+water». Water interactingwith the FCM dissolves and transports radionuclides, which, as a result, can come into the environment.
Water coming to the SO in the shape of atmospheric precipitation, condensate and dustsuppressing solutions, moving from upper marks to the premises at SO bottom marks, washes FCM
cluster and contaminated surfaces of structural materials. As a result of that processes, high-level alkalicarbonate solutions are produced, representing, practically, liquid radioactive waste. LRW leakings
produce permanent and temporary LRW clusters at Unit bottom marks. It is stated that between many
LRW clusters exist hydraulic connections.
Northern LRW flow
Northern LRW flow, whose consumption makes 700 – 800 m3/year, passes through the premises
001/3, where the biggest LRW cluster is localized (Fig.8, point 30). In that premises, numerous leakings
are collected from central and northern part of units «B» and RDAS, as well as from the cascade wall side.
Further, SO LRW flow percolates through partition wall into Unit 3 RDAS premises, and, finally, comesto premises 0005 sump (Fig.8, point 111). As soon as the sump is filled, LRW is pumped out in ChNPP
chemical shop for temporary storage and treatment. Practically, northern LRW flow represents naturally«averaged» leakings from central and northern part of Units «B» and RDAS.
Southern LRW flow
Southern LRW flow, whose consumption does not exceed 300 m3/year, passes through theLava-like FCM cluster

Assumed FCM cluster

Monitoring points

740 m3/y
620 m3/y

Low-level LRW flow

90 m3/yNon-leaked
cluster???? m3/y
MAMMOTH beam support

Figure 8 - SO LRW clusters and flows in pressure suppression pool (mark –0.650)
and RDAS unit premises (mark –2.600 and – +6.000)- 26 -

premises 017/2 and 061/2 and produces sufficiently large clusters in southern part of that premises (Fig.8,
point 18). Water level in this premises is permanent – under intensive inflow, water excess spills over thethreshold in premises 018/2, where special sewer system traps are located, or percolates in premises 025/2.
In premises 061/2, water level depends on the season – in condensation period, the level increases, in dry
period, as a result of evaporation, it reduces. Pathways of LRW leaking from that premises are not defined.
Radionuclide and chemical content of LRW
LRW radionuclide content at Unit bottom marks is formed as a result of interaction of
atmospheric precipitation, condensation moisture and technogenic solutions with the following nuclear
fuel modifications, which were produced during the accident:• «hot» particles of condensation type;• dispersed fuel in the shape of UO2 and U3O8;• lava-like fuel-containing materials.
Hot particles of aerosol-condensation type define at a significant rate the level of surface
contamination of internal premises of «Shelter» object, besides, currently, the biggest contribution into
activity is made by 137Cs and 125Sb isotopes. As a result of these particles dissolution, water contamination
occurs with caesium isotopes. The main source of «unit» water contamination with fissile elements and90
Sr are oxidated fuel particles (U3O8). Chemical stability of oxidated particles in relation to water is lower,
than that of initial fuel (UO2) and, moreover, of lava-like FCM.
Table 4 – Average concentrations of radionuclides and uranium in SO LRW main clusters
Point
numb.

Mark
m

Number ofpremises

Volumem3Component concentration, Bq/l

6

+ 2.20012/1660 m3

6.2*1079.9*106-+ 6.00

219/2

10 m3

4.0*106

17- 0.65

017/2

7 m3

18

- 0.65013/230- 2.60

31

137

90

241

Am

ΣU, mg/l

4000

1.7*10448

1.0*105--1.1

5.0*106

1.0*105

-

-

8.9

20 m3

4.0*106

0.8*105

-

-

1.1

001/3

270 m35.2*106

1.0*106360

4.0*103

3.6- 0.65

012/5

20 m3

6.1*107

8.9 *1063100

1.3*104

43

32- 0.65

012/7

10 m3

1.3*1082.2*1064200

2.8*104

110

111- 6.000005

5 m3

6.8*106

1.0*1061600

2.0*103

5.7

Cs

Sr

Σ Pu

Atmospheric precipitation, technogenic solutions and condensate during movement from uppermarks to bottom ones leach the most soluble concrete components – carbonates, bicarbonates, chlorides
and sulphates of alkaline metals. Heavy metals transfer to a solution due to metal structures corrosion. As
a result of these processes, formation itself of radionuclide, chemical and phase content of «unit» water
occurs. Averaged radionuclide content and activity of main water clusters and flows of «Shelter» object isshown in Table 4. A part of this activity is concentrated in silt sediments, and depending on dryout rate insummer-autumn period, poses a treat as aerosol source.
4. FUEL AT «SHELTER» OBJECT INDUSTRIAL SITE
During the accident and works for mitigation of its aftermath, ground layer produced at the sitearound ChNPP Unit 4, contaminated by released radioactivity. One could succeed to remove it only
partially, for site decontamination purposes the active ground was covered with clean materials. As a
- 27 -

result, an original «sandwich» produced, in which the materials were located in the following order (fromdepth - to surface):
initial ground (pre-accident) – active layer –coating materials.
It seems as important to study the active layer because of several reasons:- it may contain considerable fuel amount ;- displacement of active layer under the influence of natural factors can lead to ground waters
contamination;- conversion of «Shelter» into an ecologically safe system will demand performing works at the
Object industrial site, during which the active layer is to be touched upon, that is why one should havemaximally full information about it.
As analysis of new data shows, active layer thickness in local zone is predominantly laying within
the range of 10 – 30 cm. Total ground volume is estimated (according to value order) at 15000 m3.
Applying the research data and drilling the boreholes, it is offered to take as an expert estimate thefact that the fuel amount in local zone makes (0.75 ± 0.,25) t.
5. RADIOACTIVE AEROSOLS OF «SHELTER» OBJECT
Air migration of radionuclides from the «Shelter» object is one of the main sources ofenvironmental contamination under normal operation, and, especially, during the accidents.
Radioactive particles located in the «Shelter» object can be (very roughly) divided into two types– condensation and fuel ones.
The first particles type was produced as a result of condensation of radionuclides having
relatively low boiling temperature and coupled from the fuel during accident active stage on particles ofdust, soot, graphite, building structures, etc.
The second particles type – fuel particles produced during fuel dispersion and containing isotopesof plutonium, americium, and curium. They can be comfortably divided into two subtypes: «large» fuelparticles with size from dozen and hundred micron and «small» fuel particles with average median
diameter of 3-4 microns.
Most hazardous in terms of radiation safety are «small» fuel particles.
When performing the works in the «Shelter» object premises, concentration of alpha-active
aerosols can reach 104 admissible concentrations.
3Бк/м
1,00E-01
9,00E-02
8,00E-02
7,00E-02
6,00E-02
5,00E-02
4,00E-02
3,00E-02
2,00E-02
1,00E-02

0,00E+00
1992

1993

1994

1995

1996

1997

1998

1999

200

2001

2002

2003

Figure 9 - Estimates of annual volumetric summary alpha- beta-activity in near-surface air
aerosols of «Shelter» object local zone using aspiration facility data
- 28 -

Figure 10. Scheme of location of collectors and zones covering upgraded DSS.
In order to reduce aerosols concentrations in the «Shelter» object and their release into
atmosphere, stationary dust suppression system (DSS) was commissioned in 1989 end, which includes thesystem for preparation and supply of dust-suppressing compositions through 14 nozzles located over
«Breakdown» surface of central hall. Since December 1989 till now, more 1 000 tons of dust-suppressing
compositions were laid, that allowed significantly reducing and stabilizing the aerosols release from the«Shelter» object (Fig.9). To increase regular DSS efficiency, it was upgraded, which included assemblageof two additional collectors and 35 nozzles covering the perimeter of sub-roofing space and the space
between Unit 4 western wall and buttress wall (Fig.10).

6. SYSTEMS FOR NUCLEAR SAFETY MONITORING
Obtained recently experimental information on distribution, configuration and composition of
spent and fresh nuclear fuel for «Shelter» object individual premises does not possess the accuracy, which
would be sufficient for substantiated forecast of nuclear safety.
In existing conditions, in terms of nuclear safety provision, the «Shelter» object represents aspatially distributed uncontrollable cluster of nuclear hazardous fissionable materials without emergency
protection means.
In current real conditions, the FCM, when moderator is absent, are subcritical ones. However,generation of self-sustained fission chain reaction is not excluded when pouring with water the FCM withgreat enough fuel heterogeneity.
Currently, to monitor «Shelter» object nuclear safety, readouts of following systems are used:- 29 -

- information-measuring systems (IMS) «Finish-R», which monitors the FCM conditions (thermophysical and nuclear-physical parameters);- FCM monitoring systems (СК FCM) «Signal».Such a configuration was formed relatively notlong ago. Complex «Finish-R» is set up as an autonomous system after withdrawal in December 1998
from the structure of research system «Finish». Appropriate operation documentation was designed for it,
and metrological certification of measuring channels and hardware was made.
Since 1998, system “Signal” was accepted in pilot-industrial operation. According to its results,
the system was adopted as meeting technical documentation and transferred to normal operation mode(technical decision IA ChNPP of 26.03.2000).
7. RADIATION PARAMETERS OF «SHELTER» OBJECT
7.1 General characterization of radiation state of Object premises
Exposure dose rates (EDR) in internal premises and on «Shelter» roofing are within a very
extended range. Thus, a need appears in introducing special classification of industrial, administrative,
storage facilities and other premises and territories – to split them into zones due to radiation hazard rate.
Such a classification is realized in the document - “Provision of zoning “Shelter” object premises(2003 year).
In this document, the notion “subzone” is introduced and all the premises are split into threegroups, depending on EDR value in them:«1 subzone» — unattended premises; gamma radiation EDR > 3,3 mR/hour.
«2 subzone» — premises of periodical stay of personnel, gamma radiation EDR 3,3 - 1,6 mR/hour.
«3 subzone» — premises of permanent stay of personnel; gamma radiation EDR < 1,6 mR/hour.
Currently, distribution of «Shelter» premises due to EDR value looks like as follows (see Table 5,compiled on the basis of “Provision of zoning…»).
Table 5 - Distribution of investigated «Shelter» premises» on EDR level
Units

Radiation conditions,
R/hour

Unit «Б»

Unit «В»

Unit RDAS

to 0,50,5 – 1
1-5
5 - 10
10 – 50
50 – 100
100 – 500
> 500
Inaccessible premises

66
13
70
7
14
7
4
7
126

17

59

Unit «Г»
(А-Б)
59
6
1

4

28

Unit «Г»
(Б-Г)
140
1
1

7

The Table shows that in majority of accessible premises of reactor Unit «Б», the mean value ofgamma-radiation EDR does not exceed 1 R/hour. So, inside of more 60 of them, the EDR is lower 0,5
R/hour.
Those premises are excepted, in which fuel-containing materials have penetrated. That premises
are characterized by availability of heterogeneous, with high gradients, gamma-field EDR defined by
FCM spatial location in premises and by uranium content in FCM and its fission product. Thus, EDR- 30 -

values in premises 305/2 - 1800 R/h (mark +12.200, row И+1200, axis 46+2800) and 1 – 3 R/h (near apertureof northern sliding gate).
The premises З04/3 floor is completely filled with LFCM layer, EDR value in premises - 50 - 350 R/h.
EDR value on «heap» of 1-st floor of pressure suppression pool (prem. 012/7) makes around 400 R/h, 10
m northward – around 2 R/h. EDR over open laying LFCM of premises 210/6 SDC (И+1500, 47-400) – 300
R/h and 0,2 – 0,5 R/h over concrete surface in northern part of this premises. In central hall within the areaof scheme «E» at mark +39.000 the EDR value makes 280 R/h, at mark +49.000 – 30 R/h.
7.2 Radiation conditions on «Shelter» roofing
After explosions, roofing over CH, premises of southern and northern drum-separators, practicallyceased its existence. On neighboring roofing, numerous active core fragments were released –assembly
parts, graphite, metallic structures elements, etc. Later, during the active stage, considerable amount offuel dust dropped on them.
Immediately after «Shelter» erection, radiation conditions on its roofing was defined, mainly, by
gamma-radiation penetrating from internal premises and coming from neighboring structures. It is clear
seen considerable EDR reduction, which occurred as a result of natural decay of emitters and large
complex of decontamination works carried out on the roofing.

Figure 11 - Chart of EDR value on «Shelter» object roofing in the axes 35 – 54, rows Б – Ю- 31 -

Eventually, in «Shelter» roofing contamination, a great role began playing radioactive dust
released from the building through technological openings and coming from neighboring contaminatedroofing.
Results of radiation conditions measurement on the roofing, which were made in June 2000, theFig.11 illustrates.
7.3 Contamination rate of premises surfaces and territory
The idea of total contamination rate of surfaces in «Shelter» object premises, BK-3, RDAS, aswell as of roads and pavements at industrial site territory is shown in Table 6.

No

Table 6 - Contamination rate of premises and territory
Monitored object
β - contamination rate
α - contamination rateparticles(readout) cm ×min
Fact
RL
100
2÷3

0
0
0÷5
0÷1
0

0
0
10÷15010÷5020÷100

2

1
2
3
4
5
6

RDAS unit (premises of personnel permanentstay)
BQ-3 («clean»)
BQ-3 («dirty»)
premises of periodical personnel stay (4 unit)
premises of personnel permanent stay (4 unit)
territory (surfaces of roads and pavements insideindustrial site)

particles(readout) cm ×min
fact
RL
1
1
0
1
10
5
1

2

0
100
500
200
200

7.4 Radiation conditions at industrial site
EDR at territory close to the SO is defined by two factors: gamma-radiation of «Shelter» itself andemanation of radioactively contaminated grounds and objects located at SO industrial site.
The most contaminated is territory in close vicinity to ChNPP Unit 4, so called local zone of«Shelter» object. Distribution of exposure dose rate in local zone of SO industrial site is shown in Fig.12.
The chart of EDR distribution demonstrates that the contamination of territory has heterogeneous
character. Analysis of EDR chart gives a reason to assume the existence of notable contribution ofradiation from the SO side from the area of staircase-elevator unit. However, such evident influence iswell observed only in a place being close to the SO.
SO influence onto volumetric EDR distribution over industrial site is well illustrated in Fig.13.
Gamma-field intensity increases in eastern direction (when approaching to «Shelter» object) andgrows with more height.
Abrupt growth in direction to Unit is observed within the area of row А. One can assume that acause of above abnormality can be local intensive gamma-radiation sources located on the roof of turbinehall and deaerating stack.
8. Carried out and planned SO stabilization measures«Shelter» object is a unique spatial building, whose structural scheme represents a combination of
two constituents:• «old» structures of destroyed power Unit 4;• «new» structures erected in the year of 1986 during «Shelter» construction.
Post-accident conditions of power Unit 4 «old» structures are characterized by total or partial
destruction, large damages of remained intact elements and junctions, overloading of weight of structures
obstructions and equipment collapsed on them, as well as the materials, that were used during accident
mitigation period. Bared armature and metal structures are subject to corroding processes. Availability of- 32 -

Figure 12 – Chart of exposure dose rate distribution in local zone as of January 1, 2002.
such serious defects requires permanent survey over conditions of these structures and taking, in case ofneed, of stabilization measures.
The «new» structures that were erected after the accident (protective-partition walls and coating’s
metal structures) were designed in conformity with norms and rules of structural design valid in that time
period. However, for this group of structures also the problems exist of their reliability and longevity
provision that conditioned by following reasons:• technologies of remote assemblage and concreting in complicated radiation conditions that wereapplied, restricted possibility to control the quality of work production ;- 33 -EDR, mR/h
_ 60
_ 50
_ 40
_ 30
_ 20
_ 10

a

b

c
Figure 13 – Model of gamma-field in NSC erection zone (June 2004)a – cross-section along axis 54 + 120 m;
b – cross-section along axis 54 + 156 m;c – cross-section along axis 54 + 226 m• structural elements are fragmented – not connected one to another, rest freely upon bearing
structures without physical connection and are retained in designed position due to friction forces(i.e. welded-, bolt or other strengthenings of support parts are absent);• access is embarrassed to elements and metal structures joints for periodical survey and recovery ofanticorrodent coating.
The first document, in which a general estimate was given of «Shelter» building structures
conditions, was the «Conclusion on reliability and longevity of coating’s structures, as well as on radiation- 34 -

safety of reactor department of Chernobyl NPP Unit 4», set forth by Government Commission on October
11 1986 to special commission of USSR Gosstroy.
The «Conclusion …» included as regards:«Considering low corrosion velocity within the conditions of structures work, under performed
protective coatings, one can regard as provided their service life:- for pipes 30-40 years,- for beams 30 years».
Unfortunately, in later period these figures, as it were legalized not only for service life of newly
erected metal structures, but also for all «Shelter» object as a whole. Often the time of 30 years wasindicated in documents, as guaranteed time for safe conditions of «Shelter» object.
At the same time, the mentioned «Conclusion…» had as written:«In connection with the fact that the shelter of reactor department is being erected on destroyed
structures and within the conditions of high radiation levels, it does not seem as possible to obtain reliabledata on their bearing capacity, as well as, considering the complexity of structures installation and controlof their position..., that leads to essential reduction of bearing capacity of remotely assembled
structures...».
So, the main conclusion was that within the conditions, in which the Object was erected, it is
impossible to reliably assess its longevity.
That is why immediately after the construction was completed, the works started for research ofreliability and additional strengthening (stabilization) of «Shelter» basic bearing structures.
As a whole, three main stages of such works can be distinguished.
During the first stage (1987 – 1991), researches and certification of accessible premises wereconducted, and zones of emergency conditions of building structures, which influence the «Shelter»
general stability and integrity, were identified.
Three zones were identified that demand conduct of immediate anti-damage works: deaeratingstack (premises 635/3), premises for MCP motors (premises 402/3), premises for exhaust ventilation airducts (premises 805/3).
When surveying the upper tier of deaerating stack framework (rows Б-В axes 41-51) it was statedas regards: columns between the marks +24.27 and +38.60 inclined from vertical to turbine hall side atvalue 700 - 1100 mm. In places of column junction in mark level around +24.30, fractures produced witharound 150-mm wide crack opening, longitudinal effective reinforcement had broken, crack penetration
depth into column cross-section depth made 0,6 - 0,9 m. Rigid joint couplings of column and girder werealso destructed, that is confirmed by rupture of upper effective reinforcement rods of extended zone andgirder shift from supporting cantilevers into mark level +38.60 at 70 - 150 mm. Simultaneously, on theceiling (above mark +38.60), obstructions of building structures, equipment and materials produced,
which were used during the mitigation of accident aftermath, of height being 3...5 m.
Such conditions of upper tier framework structures of deaerating stack were classified as
emergency one. Seriousness of situation was conditioned by the fact that the damaged columns along therow Б were overloaded due to leaning against them coating’s structures over turbine hall. Destruction ofcolumns would provoke a collapse of this coating, as well as of other metal structures of «Shelter»
southern part («Octopus» beam, southern boards-“clubs”). Under a more unfavourable situation
development, collapse of «Mammoth» beam supports and a probability of subsequent collapse of metal
structures of central hall coating were not excluded.
Based on data collected on conditions of upper tier framework structures of deaerating stack,strengthening of upper zone of ferroconcrete columns of row Б was operatively realized by way of
installation of inclined tensions made of two channel bars No 16 welded to dearator tanks filled with the- 35 -

concrete. Simultaneously, knees made of two channel bars No 24 were installed to strengthen the center ofgirder span in mark level +38.60 (Fig.14).

Club cover boards
Octopus beam

Mammoth beam

Initial cover overT rbine HallClub cover boards
Octopus beam

Mammoth beam

New cover over Turbine Hall

Figure 14. Structures, whichstrengthen deaerating stack
framework:А - pre-strengthening conditions;Б – post-strengthening conditions.

Fer. Con.
wall

Besides, in 1988, trusses of turbine hall coating were dismantled, which were resting upon the
cantilevers of row Б columns (design decision of 1986), and instead of them the new coating wasassembled with resting upon steel-concrete walls, newly erected in turbine hall between the rows А-Бalong axes 41 and 49.
As a result of examination of MCP motors premises (premises 402/3) between the rows Г-Е axes
41-50, it was stated, that wall and columns along the row Г had inclined to row В side of deaerating stack.
In the level of supporting cantilevers (mark +30.30), the columns displaced to row В side at 400...600 mm.
In coupling joints of girders with the columns, ruptures of upper rods of girder armature and considerable
concrete breakoffs were observed.
Column framework and ceiling conditions (mark +31.50) over premises 402⁄3 of southern MCP
motors also was recognized as emergency ones.
The strengthening of indicated ceilings concluded in strengthening the supporting sites of girders
and was realized by means of installation of the supporting steel structures under girders within the area of
their resting upon the column cantilevers (Fig.15). The strengthening structures represented bearing steel
trusses, united in spatial units by system of horizontal and vertical connections, and thereafter wereremotely slided in designed position along existing crane railways of bridge crane using the winches.
As a result of examinations it was stated that the ceiling (mark +35.50) over premises of exhaust
ventilation air ducts (premises 805/3) between the axes 40-50, rows В-Е, is also in emergency condition- 36 -

Figure 15. Scheme of MCP premises
structures strengthening.
and requires the urgent strengthening. Couplings of ferroconcrete girders with the columns along the row
Г and ferroconcrete wall near row Е are partially destroyed, the girders are displaced from supporting
cantilevers.
The ceiling strengthening was performed by way of erection under the bottom girth offerroconcrete girders of cribworks made of antiseptized wooden half-sleepers (Fig.16).

Figure 16. Scheme ofstrengthening ofstructures ceilings overpremises 805/3.

After the earthquake within the ChNPP area on May 30 and 31, 1990, being of 3,5 - 4 number
intensity, the «Shelter» was investigated and “Certification of «Shelter» object conditions investigation”
written, which reads that no position changes and notable deterioration of main building structures
conditions were fixed.
Research peculiarities of the second stage (1992-1997) concluded as regards:• extension of research volumes (additionally, supporting structures conditions was assessed ofwestern fragment - ferroconcrete wall along the axis 50 with adjoining framework and walls
between the axes 49-51′, supporting joint units of Б1 beams and Б2 on the wall along axis 50,
protective-partition wall and coating’s metal structures, foundation grounds, adjacent structures ofunits В and RDAS);- 37 -

•

complex approach (combination of field investigations with probabilistic analysis andcomputational modeling, with creation of physical models).

Figure 17. Strengthening of Б1 beams
supporting parts and ferroconcrete wallalong axis 50 in place of resting upon itof Б1 beams unit (row Ж)Figure 18. Strengthening of Б2 beams
supporting parts and ferroconcrete wallalong axis 50 in place of resting upon itof Б2 beams unit (row Ж)

Field investigations have revealed a range of major defects of ferroconcrete wall along the axis 50,
which influence essentially not only on bearing capacity and stability of above wall, but also the westernfragment as a whole, as well as supporting joint units of Б1 beams and Б2 along the row Ж and П. Shift ofwall upper part within the area of abutting of Б1 and Б2 beams units (mark +58.50) in relation to wallbottom part (mark +12.50) makes 500-700 m near row П and around 1000 m near row Ж. Indicated- 38 -

position of bearing wall was considered in erecting the «Shelter», on the site of abutting Б1 and Б2 beams
unit along axis 50 row Ж, a need arose in installing a concrete support in non-removable bearing metallic
casing. Because of a range of reasons, design decisions for installation of such a support (andsimultaneous local wall strengthening) were not fully realized.
Using the results of field investigations, which were made in 1993, actual parameters of indicatedmetallic casing were defined, conditions of its resting upon structures obstructions and on the wall along
the axis 50, as well as the rate of its filling with concrete. The conditions of Б1 and Б2 beams supports unit
along the axis 50 row Ж were recognized as unsatisfactory.

Figure 19. Strengthening of Б1 beams
supporting parts and metallic support
under Б1 beams in place of Б1 beams
unit abutting on ferroconcrete wallalong axis 50 (row П)Figure 20. Strengthening of supportingparts Б2 beams and metallic supports
under Б2 beams in place of Б2 beams
unit abutting on ferroconcrete wallalong axis 50 (row П)

In 1994, strengthening of support by way of erection under bottom girths of Б1 and Б2 beams unitof metallic posts abutted on concrete surface inside the casing. However, metallic posts installed in 1994
in conformity with indicated design did not strengthen the support, and were seen as made for the safety,- 39 -

since were installed on concrete body, which together with metallic casing rests upon the preserved ceilingfragment at mark +49.95 through the obstruction of building structures.
At the next third stage (since 1998 till now), researches and works for strengthening «Shelter»
main bearing building structures acquired system and large-scale character, and they are performed within
the framework of international cooperation.
The works started from the strengthening of ventilation pipe (VP-2) structures. Organizations of
Ukraine, USA and Canada were involved in them. Strengthening started late in 1997 and was successfullycompleted in 1998 summer.
Further works for investigation and stabilization of «Shelter» object structures were continued inconformity with Shelter Implementation Plan (SIP) at the «Shelter» object with direct participation ofInternational Consortium ICC (MK) JV (MORRISON KNUDSEN (USA) – leader, BNFL (UK),
Ukrainian organizations NIISК, KIEP and ISTC «Shelter») – Package A tender “Civil engineering”
winners.
As an urgent measure of SO building structures stabilization, consortium ICC (MK) JV prepared
the draft design of strengthening Б1 and Б2 beams supporting joint units along axis 50, which foreseen thestrengthening of both supporting sites of metallic beams and of the sites of wall, on which they leanagainst (Fig.17-20). The project was realized by Ukrainian building organization «Ukrenergobud» in theyear of 1999.
According to results of additional field investigations and refined estimates, consortium ICC(MK) JV substantiated the list comprising 15 stabilization measures, whose realization allows providing
structures stability during the time exceeding 15 years, i.e., more, than it is needed for construction andcommission of new safe confinement (NSC).
Later this list was reduced to 8 stabilization measures, that is fixed in program decision P2«Decision for stabilization strategy of roofing, support and structures» of December 24, 2000. Thisdecision is based on changed design criteria in the part of changing designed tornado loading for extreme
wind loadings.
During 2002-2003, the consortium KSK comprising Ukrainian organizations KIEP, NIISK and
ISTC «Shelter» developed and accorded with regulatory bodies the draft design of stabilization measures.
Recently, the works started for its realization.
Developed measures were grouped for the following SO zones.
WESTERN ZONE
Stabilization of “Shelter” object western zone covers the strengthening of western fragment,
which includes:• western buttress wall;• framework and unit Б walls along the axis 50, 51′ between the rows Д – С;
• Б1, Б2 beams support units along axis 50 rows Ж and П;• coating between the buttress wall and the wall along axis 50 between the rows Д-С.
Strengthening idea covers the erection of two metallic spatial rod towers with plan sizes being
12×15 m, total height 48 m, with 23-m spatial cantilever span in east direction (Fig.21) to buttress wall
west. Indicated towers are installed at mark+14.00 between the rows Е-И and Н-Р in the axes 53-57 on
ferroconcrete foundations and connected one to another by spatial systems (trusses) in north- south
direction in two levels. The first level corresponds to marks from +26.00 to +32.00; second level – tomarks from +44.00 to +50.00. From the eastern side, to spatial truss of second level the brackets are
fastened with the step 6 meters that are located in vertical plane, on whose end an abutment of h-beamcross-section is envisaged, adjoining to framework and wall structures along axis 51′. Abutments andbrackets are destined for taking horizontal forces in «east-west» direction from the framework and wall
- 40 -

Figure 21. Stabilization measures 2 «Strengthening of western fragment». Scheme of strengthening’s
metal structures.
along the axis 51′ and therewith prevent the wall displacement in western direction. Towers cantilevers arelocated in Б1 and Б2 beams units range along the rows Ж and П. At the mark +60.00, on cantilevers ends
the welded beams are envisaged, on which by means of special joints at mark +60.55 reconstructed buttends of Б1, Б2 beams supporting parts units are abutted. At the mark +56.65, on cantilevers, abutments areenvisaged in the wall along the axis 50, which are destined for taking probable horizontal forces fromseismic impact in «east-west» direction, thus, strengthening the bearing ferroconcrete wall along the axis
50. Besides, on towers cantilevers the spatial truss is abutted of western fragment coating (spatial systemof 3-rd level), to which the upper ends of coating knees (mark +58.525) are fastened.
Ferroconcrete foundations under towers are performed in local zone to buttress wall west between
the axes 53-59 and rows Д-К и М-С. Concreting of foundations is tentatively assumed from the mark+0.20 to mark +14.00 – foundations top. Between the axes 54-56, foundations are abutted on foundation
plate and bearing unit of buttress wall.
Thus, the works for western fragment stabilization will be performed in local zone, in closed space,between the buttress wall and wall along axis 51′, in upper part of ferroconcrete wall along the axis 50 at
the levels from mark +56.40 to mark +58.50 along the row Ж, and at the levels from mark +57.40 to mark+58.50 along the row П, under «Shelter» object coating, as well as on western fragment coating.
SOUTHERN ZONE
Stabilization of deaerating stack framework must be realized by way of strengthening theframework structures of deaerating stack upper tier along the axes 42-50 and rows Б, В. The works will be
performed in non-developed premises Г635/3, whose floor level corresponds to mark +24.27.
Strengthening envisages the installation at mark +37.50 (under ceiling girder with mark +38.60)
additional horizontal struts fastened to internal blind walls along the rows Б and В and to upper support
unit, installed earlier under the girder, as well as the installation at marks +28.40 and +32.90 two more
struts (connecting elements), between the inclined knees of additional support.

- 41 -

Figure 22. Scheme of location of connection truss on «Shelter» object coating that unites southern«boards-clubs» and southern roofing boards in a rigid disk
Strengthening provides the taking of estimated seismic loadings in “north – south” direction.
Connection of «southern boards-clubs» with «southern boards».
Installation of connection elements between ‘southern boards – clubs” and “southern boards” ismade on outward surface coating, on its southern slope, at the site between the axes 41 and 50 along therow В, i.e. over the place of their resting upon the “Mammoth” beam (Fig.22).
Connection will provide withstanding the extreme wind and seismic loadings.
Stabilization of western support of “Mammoth” beam.
All braces of support’s vertical connections are strengthened by way of welding to each brace Lbeam of additional L-beam forming “small box” with the existing one.
The strengthening provides the taking of extreme, including seismic loading, in “east – west”
direction.
NORTHERN ZONE
Two measures are planned to simultaneously perform here:- strengthening of northern buttress walls along axis С and its coupling unit with northern clubs;- uniting of northern boards-clubs with northern buttress wall using anchor-clamps.
Unification of northern boards-clubs with northern buttress wall will be made by way of
installation and strengthening of anchors-clamps on supporting cross-arms of boards-clubs. Anchor parts
being sealed are placed in partially concreted wall space and made monolithic when filling with theconcrete the space of wall upper part, which was not fully concreted during the erection.
The concreting of upper part of northern buttress wall till designed mark provides its bearing
capacity.
Installation of anchors-clamps provides the bearing capacity of northern clubs for horizontal
loadings, including extreme ones.

- 42 -

EASTERN ZONE
Local stabilization of ventilation shaft walls, which support the Б1 beams.
Stabilization is reached by way welding from bottom part to Б1 beam support plate the two
abutments made of L-beams that closely adjoin from the both side to wall lateral surfaces, on which thebeam is leaned against. Strengthening provides the durability of Б1 beams abutting zone by way of
involvement in work for horizontal loadings of all ventilation vault wall thickness.
The strengthening of “Mammoth” beam eastern support, under which the cavities existing infoundation support from northern and eastern side, must be filled with the concrete. Concreting is assumed
to perform in a fixed metallic casing-iron-ring.
The fulfillment of planned scope of building and assembly work (BAW) for building structures
stabilization within «Shelter» object conditions is a sufficiently complicated engineering task. First of all,it is related to the problem of safety provision for personnel involved in these works, and maintenance ofappropriate and sufficient level of radiation and ecological safety of the Object. To decide that tasks
within the framework of stabilization project, a range of documents was developed that substantiate thesafety during realization of stabilization measures. The main documents include as regards:• Report on radiation safety;• Report on environmental impact assessment;• RAW management program.
Radiation safety
Development of design decisions and measures providing radiation protection within the “Shelter”
object conditions started from analyzing radiation conditions in assumed workplaces and ways of
personnel movement.
After completion of conceptual developments for stabilization, complex pre-project researches
were conducted. They also included investigation of radiation conditions.
When developing structural and technological decisions, traditional methods and technologies
were applied, which are realized in organizing radiation protection at the «Shelter» object. First of all, they
include as follows: protection with time and distance, shielding, use of remote technologies, etc. Taken
decisions allowed performing the main assembly works using remotely controlled load-lifting crane, andthe sites for acceptance of articles and metal structures, prefabricated assembly were removed at
maximally possible distance from the «Shelter» object. Besides, the sites will be shielded from the SO by
a protective wall, which will provide the personnel protection during assembly works. An important stage
for reducing collective effective dose was the choice of optimal access ways for personnel and loaddelivery. This circumstance has especially essential character during the work in zones with enhanced
EDR values, when changeability of a group or brigade in a shift is made several times.
All complex of measures for provision of personnel radiation protection, during SO stabilization
work, is divided into following measures groups:• organizing;• radiation-hygienic;• technical.
Within the “Shelter” object conditions, the measures of first two groups are compulsory.
Their application is regulated by “Shelter” object documentation, and their realization provides theobservance of non-exceeding principle.
The organizing measures include:• contractor’s personnel training;• organization of work production;• control and supervision.

- 43 -

Special contractor’s personnel training is realized in personnel training centre (PTC) in the townof Slavutich (theoretical training) and at the SO industrial site (practical training). To upgrade thepersonnel skills for individual technological operations, training ground is created with mock-ups of future
workplaces.
Choice of breadboarding units and conditions defining the need in preliminary trainings was madeaccording to the following main indices:• constrained conditions в planned places for work conduct;• considerable EDR value at workplace;• complexity of constructive decision realization;• opportunity to apply known experience.
When the personnel is trained at mock-ups, the following items are perfected:• estimate of acceptability of adopted equipment application;• skills during fulfillment of operations;• technological process of assembly of strengthening’s metal structures;• time-keeping of all operations;• recommendations to reduce dose expenses.
To improve the work conduct safety, as well as to check the observance by contractor for
erection of design decisions, including the measures for radiation protection, permanent supervision
will be provided over the fulfillment of building and assembly works. Especially, one should monitor
the accumulation of collective effective dose (CED) during work production. The above will allow
comparing the real collective dose to designed values, and, in case of need, to make in proper time
the corrective actions.
Radiation-hygienic measures include as follows:• sanitary-hygienic zoning of work conduct place and sanitary-hygienic classification of works;• provision of personnel with main and additional individual protection gears (IPG), as well as
check of their correct application;• provision of personnel with appropriate equipment and means of personal and collective hygiene;• medical services and rehabilitation;• organization of dosimetric control.
To minimize the prevention radioactive substances transport beyond WPZ boundary, except
general requirements to zoning, additional zoning of workplace is envisaged, that is concluded as regards:
within the limits of a subzone the sites are defined with different essentially differing levels of radioactive
contamination. At the boundary of these sites, transport sanitary locks are located, which provide minimal
spread of radioactive substances along «Shelter» object territory. Organization of permanent radiation
control in these places was defined in conformity with the ALARA principle.
Choice of individual protection gears (IPG) is made in conformity with requirements of regulatory
and operation documentation. Volume and nomenclature of additional IPG application was defined in
dependence of activity type:The factors defining the choice of IPGRO types, include:• character and quantitative content of radioactive and other harmful substances in air (aerosols
disperse content and toxicity, availability of steam phase, harmful substance concentration);• microclimatic conditions at workplace (temperature, relative air humidity, thermal radiation);• in-air oxygen content at work conduct site;• heaviness of work being performed;• protective and operation properties of individual IPGRO samples.
Additional factors, defining the choice of IPGRO types in specific work conditions for structures
stabilization, are as regards:- 44 -

••••

work conduct time;density of surface contamination with radionuclides;
EDR value;
work conduct conditions (works in closed space, constrained conditions).
For substantiated choice of IPGRO types, measurement of labour conditions indices is needed,which includes the both radiation condition indices, and microclimate indices in the WPZ. Special
attention will be drawn to measurement of radioactive substance concentrations directly in the breathingzone of workers, since when performing some technological operations that concentrations can, dozens,hundred and, even, thousand fold, exceed their average-shift or average-day values defined withapplication of stationary samplers.
To protect the personnel from beta-radiation, use of protective eyeglasses, shields and dashboards
is planned.
For personnel entry to contamination control area (CCA), sanitary checkpoint for 1430 persons
will be used. Personnel passage directly to work performance zones will be made through the stationary
sanitary locks in deaerating stack. During work production time, additional temporary sanitary locks are
assumed to install in the local zone.
Dosimetric control is an integral part of all radiation safety system during realization ofstabilization work. As far as the monitoring of external exposure is concerned, the means existing at«Shelter» object are sufficient and adequate to requirements during realization of stabilization measures.
Commission of state-of-the-art system of individual dosimetric control (IDC) will improve the situation,
since it also meets the requirements for monitoring of external beta-exposure and neutron (emergency)
exposure. The operative control of internal exposure can be improved with installation high-sensitive SHE,
which will be placed in premises of new sanitary check point, and daily double (before and after shift)monitoring of personnel exposure, which works in the most contaminated work zones, as well as
biophysical personnel monitoring.
Shielding is the most effective method of protection of personnel staying in work production
zones. Shielding of work production zones and access ways to them will be set up as permanent or
temporary.
Permanent shielding represents the boards-shields manufactured of protective materials andplaced in special metallic framework. The boards can be installed on existing structures or on new metal
strengthening structures (MSS). They are installed during the preparative work and, without absolute need,
are not subject to subsequent dismantling.
Under temporary shielding, specially created sliding protective buildings of box type (PB),
shielded attached and sliding sites, is implied. Their manufacture is assumed to make at a plant locatedoutside the exclusion zone. Depending on box location places, they are destined for personnel stay duringforced technological breakdowns, control and survey over work process, putting on and off additional IPG,
etc.
Except temporary and permanent shielding of work production zone, local shielding of radiation
sources can be used – first of all, radwaste clusters close to workplaces. This shielding method can beapplied in case of detection (e.g., during obstructions clearing) of intensive radiation sources, and theirremoval from work zones is embarrassed by different circumstances (e.g., source is located under aconcrete layer).
In conformity with ALARA principle, the decisions being developed for shielding were optimized.
That process included the reduction of collective effective dose (CED) for personnel, as well as
optimization of shielding facility installation thickness and choice of their installation place.
Most important factor for shielding optimization is the data on gamma-radiation angular
distributions at workplaces. Optimization was made in the following sequence:- 45 -

•

analysis of results of angular distributions measurements of gamma - radiation intensiveness close
to workplace;• definition of direction to main sources forming EDR in measurement places;• gamma-radiation sources are identified for measurement places;• forecast of probable location of sources defining EDR at workplace with considering the distanceto sources, possibility to shield workplace from the source by «Shelter» object structures;• estimate of relative contribution into EDR from identified sources;• estimate of contribution into EDR of radiation from six main directions, which can be shielded.
When shielding the access ways, as the main parameter defining expediency of shielding,intensity factor of using defined route sites is accepted. Considering large labor expenses for displacement
and installation of shields, in the routes inside the «Shelter» object, where is impossible to hoist the shields
with load-lifting mechanisms, a conclusion was made on inexpediency of manual shielding of access ways.
When choosing a material for shielding, analysis was made of main characteristics of different
materials applicable for gamma – radiation attenuation: lead, steel, concrete, tungsten and depleted
uranium.
The analysis has shown, that for work inside the «Shelter» object, the lead is the most preferable
material. Use of expensive materials with big atomic number gives no principal advantages, but only
increases the design costs.
A quantitative characteristic of efficiency of shielding measures application is preventable CED.
According to estimate data, the preventable collective dose of personnel, due to shielding, made more 35
Sv.
During stabilization works, a need will arise of involvement of large amount of people (to 150
men per a shift) and machinery. On top of that, simultaneously will be performed large scopes of work in
different places, both inside the object, and on industrial site territory. Such a work organization requires
an effective management of personnel and of industrial processes. The use of video survey will allow
reducing the exposure dose for «Shelter» object personnel and for contractor organizations due to controlof observance of installed routes, allowed work time, as well as preliminary familiarization of contractor
personnel with the place and character of work conduct. Using video survey system, permanent presenceof work leader in place of their conduct is not required in conditions of unfavorable radiation situation.
Estimate of expediency of dust suppression works was based on comparative analysis of positive
and negative factors of measure realization.
As positive factors, the following items are considered:• prevention of dust production during the works and movement of personnel, reduction ofprobability of additional internal exposure;• exclusion of probability to transport the dust arisen during personnel movement behind theboundaries of working site and its precipitation on the personnel, which is not linked with theconduct of stabilization measures;• minimization of environmental influence.
To negative factors additional material expenses, labor- and dose expenses for dust suppression
realization can be referred.
When arranging the WPZ and access ways, decontamination is inexpedient, if it will provide
reduction of external exposure dose. For instance, the removal of detected sources of intensive gammaradiation can essentially improve the work production conditions. Such sources can be detected whenclearing the WPZ territory, removal of concrete inflows, etc. In considering the expediency of
decontamination of WPZ surfaces, e.g. cutting-off of apertures along buttress wall height,
decontamination is recognized as inexpedient one. Exclusion makes the decontamination of internal andexternal surfaces of protecting boxes.
- 46 -

Welding and fire works during realization of stabilization measures are performed outside thestructures fencing «Shelter» object or in premises having considerable sizes (e.g., breakdowns of premises
2001/4, 2007/3 et al.). Radioactive aerosols being produced are to be removed. That is why an actual
becomes organization of safe removal of discharged air, since this flow can lead to radioactive aerosols
resuspension, which will entail considerable increase of radioactive substance concentrations not only in
the WPZ, but also in adjoining premises and territory. The above, first of all, is related to the works ininternal premises, where the place of probable air release can be distant from WPZ more than at 50 m.
Use of local fan is taken as inexpedient only in individual places.
Assessment of environmental impact
The “Shelter” object being an ecologically hazardous facility represents an enhanced treat
associated, in first turn, with the penetration of radioactive substance into environment. Despite the factthat currently the radioactive releases from the SO are lower than established reference levels, hazard
exists of their considerable intensification as a result of realization of measures for SO structures
stabilization. When drafting the project, impacts were assessed to aerial, water mediums, as well as on
topsoil, social and technogenic media.
Based on building decisions, release values were estimated in conducting different stabilization
works. Results of estimates of radioactive substance releases for each measurement are shown in Fig. 23.
Impacts onto aerial environment.
Because of the fact that radioactive release sources are located at different height over earth level,that essentially influences the spread and transport of radioactive substances in aerial environment, releasesources grouping was made on this attribute and summary release was calculated. It allowed obtaining
maximally probable volumetric contamination at any distance from the SO.
Thus, release sources from earth level are forming a release being of 8,12·106 Bq, from sources
located at SO roofing level, the release will make around 1,88·109 Bq, and release from ventilation pipe
(VP-2) will make around 3,2·108 Bq.
In Table 7, maximally probable volumetric air contaminations at 10-km and 30-km distance areshown, ДКА and ДКв, as well as comparisons of concentrations with admissible.

Fig. 23. Releases during realization of different measures- 47 -

Table 7
Admissible
concentrations,
Bq/m3
ДКа
ДКв
60
0.8
10
0.2

Concentrations under normal
operation,
Bq/m3
10 km
30 km
0.009
0.003
0.008
0.002

Relation to
ДКа
10 km
0.00020.0008Relation to ДКв
30 km
0.004
0.01

Nuclides
137
Cs
90
Sr
Alpha-emitting
transuranic
0.03
0.00040.00055
0.000160.018
0.40
isotopes
As Table 7 demonstrates, in normal conditions of work realization, impacts to aerial environment
will be considerably less than admissible levels.

Impact to soil.
The main way of radioactive substance coming onto topsoil is natural precipitation on soil surfaceof radionuclides from radioactive release in the air, which are produced during the SO stabilization.
Estimates have shown, that the operation, which exerts the most impact to soil medium at small
distances from the SO - territory planning in local zone, and at a more distance from the SO - averagerelease during realization of all stabilization measures.
Table 8 shows maximally probable surface contaminations at 10-km distance, as well as theircomparison with the RL.
Table 8
Surface contaminations under
Relation toReference
Nuclidesnormal conditions at distance 102RLlevels, Bq/m
km, Bq/m2
137
3.1
Cs
90
2.8
Sr
Beta sum33300
6.0
0.0002Alpha-emitting transuranic333
0.2
0.0006elements
The data demonstrated in Table 8 give the reason to conclude that under normal conditions ofwork conduct for stabilization, the impacts to soil will not exceed the RL.
Impact to water medium.
Due to small values of radioactive releases to air under normal conditions of work conduct, eventotal penetration of this activity into water medium will not notably reflect at value of its contamination(activity release from exclusion zone by river Prypyat makes around 5⋅1012 Bq/year).
Impact ways to water medium under an accident - radionuclides precipitation from air release, as
well as, washout from soil surface.
A conclusion is made, that under normal conditions of work conduct, and under an accident, no
supernormative impact to water medium will occur.
Effective dose.
Under normal conditions of work conduct, the dose obtained in the maximum of near-surface
concentration, makes around 4 mkSv.
In case of an accident with maximal aftermath, effective dose at 10-km distance will make around
4 mSv, and under a condition, that a man will stay during the accident from lee side from the SO and will
- 48 -

not use any IPG. At 30-km distance (at the boundary of exclusion zone), effective dose will make around
1 mSv.
Impact to plant and animal world, reserved objects.
As a result of stabilization activities, the most probable impact to plant and animal world will beradionuclides penetration into adjoining ecosystems of neighbouring territories in aerosols composition.
On top of that, summary average daily activity amount under a release, which is produced by SO
stabilization measures, is essentially less of reference average daily levels of radionuclides releases
through VP-2. Based on above, a conclusion is made, that radiation constituent will no exert any influence
to natural topsoil of adjoining territories and faunal complexes.
Impacts to social environment.
A large scope of works, which is planned to realize during SO structures stabilization, stipulates
the involvement of considerable amount of additional personnel, that can exert indirect positive impact toconditions of social environment of the town of Slavutich – satellite town of ChNPP.
Closure of hail growth enterprise, which for Slavutich is ChNPP, increased essentially theprobability of deterioration of social status of majority of town inhabitants. Emotional stress provoked by
the above exerts a negative impact to psychological condition of public that produces general deteriorationof vital activity conditions. Origination of new opportunities for job placement, due to planned SO works
will serve to strengthening of confidence in the future and will enhance public well-being.
Guaranteed provision of employment for a part of public when performing the work at the SO,
will serve as a factor, contributing to improvement of social environment conditions of Slavutich and for apart of public of other Ukraine’s regions.
Analysis of probable impacts to exclusion zone personnel and public, which dwells behind its
limits has shown, that a solely probable impact type is radiation factor. Estimates of additional dose
loading to personnel and public are conditioned by trouble-free work conduct for SO stabilization, testify anegligibly small size of impacts.
Impact to technogenic medium.
At the territory adjoining to SO, acting facilities of housing and communal services and sociocultural assignment are absent, as well as monuments of architecture, history and culture guarded by theState. In zones of probable impacts, recreational zones and cultivated landscapes are absent.
Stabilization activity does not assume any change of existing conditions of operation ofenterprises located (or planned) at ChNPP industrial site and behind its limits (SNFR-2, ПКО SRW et al.).
That is why, a solely factor of impacts is the increase of dose loading to personnel of these enterprises.
Carried out analysis has shown, that dose loading increase under normal work conduct (maximally 0,0042
mSv) will be negligible.
Performed assessment of environmental impact allowed developing adequate protective measures.
The main measures include as regards:• survey over radionuclides penetration into environment during the work conduct for SO
stabilization (radiation monitoring);• radioecological monitoring of personnel working in ChNPP close and far zones.
Radiation monitoring of natural media, during conduct of SO stabilization measures, must provide
obtaining of reliable data on current radiation conditions of components of medium undergoing theimpacts. Currently, existing routing monitoring net covering the major part of exclusion zone territory
satisfactorily provides representative radioecological monitoring of current conditions of environmental- 49 -

components. It is a sufficient one and there is no need in its expansion and inserting of additional items
into existing regulation.
Thus, realization of stabilization measures will increase «Shelter» object radiation safety, andduring the conduct of building and assembly works, human and environmental radiation protection will be
provided.
9. NSC conceptual design
Creation of New safe confinement (NSC), as a part of activity for «Shelter» object (SO) conversion
into an ecologically safe system is regulated by ratified by Ukraine of international laws [1-5], laws of
Ukraine [6-13], regulatory-legislative acts [14-21] and other documents.
The funds for design are granted by European Bank for Reconstruction and Development (EBRD)
on behalf of donor countries.
Conceptual design (Feasibility report) of New safe confinement (CD (NSC FR) was developed byorder of State Specialized Enterprise Chernobyl Nuclear Power Plant (SSE ChNPP, town of Chornobyl)
by Consortium (comprising: Bechtel International Systems (USA); Electricite’ de France (France); andBattelle Memorial Institute (USA)), which performed the works with participation of Ukrainian
consortium KSK (comprising: Research and Development Institute for building structures (NIISK, cityof Kyiv); Kyiv Research and Development and design-constructor Institute «Energoproekt» (KIEP, cityof Kyiv); Interdisciplinary Scientific-Technical Centre «Shelter» (ISTC «Shelter», town of Chornobyl)).
Creation NSC is one of the main stages of conversion of «Shelter» object, representing a treat forenvironment, into an ecologically safe system.
In conformity with Provisions of Law of Ukraine «Of general fundamentals of further operationand decommission of Chernobyl NPP and conversion of destroyed power Unit 4 of this NPP into an
ecologically safe system», NSC creation must provide the achievement of the following goals:• provision of protection of personnel, public and environment from influence of
nuclear and radiation hazard sources associated with the SO existence;• provision of conditions for realization of activity aimed at SO conversion into an ecologically safe
system, including for dismantle/strengthening of unstable SO structures, FCM removal and RAW

Figure 24. General view of NSC- 50 -

management.
Based on above goals of NSC creation, its functions are defined as follows:• Restriction of radiation influence to public, personnel and environment by established limits
under NSC normal operation, violation of normal operation, emergency situations and accidents,
including the accidents during the dismantle of unstable structures, and future handling of FCM andRAW;• Restriction of spread of ionizing radiation and radioactive substances located in the SO undernormal operation, violations of normal operation, emergency situations and accidents. The conduct of
this function is provided by:- integrity of NSC fencing structures during a long-term operation period;- prevention of SO unstable structures collapse, by means of their dismantle or strengthening fora period defined by conditions of NSC safe operation;- restriction of penetration of rain (storm) and from melted snow water;- protection of groundwater from contamination with radioactive substances, located in SC.
A general view of NSC is shown in Figure 24. In architectural design, the NSC will present acomplex of buildings, which comprise:• new fencing structural casing;• internal premises for placement of NSC system equipment, control boards, doghouses and sites
for primary treatment of dismantled radioactively contaminated elements;• auxiliary buildings (sewer-pumping station, building of fire-extinguishing facility, et al.).
Conceptual design envisages the creation, within the framework of NSC design, of thefollowing elements:• Load-lifting mechanisms to provide the works for NSC operation and SO conversion into an
ecologically safe system;• Systems providing the NSC operation.
New fencing structural casing will represent a metallic structure of arched type with gables.
Arched structure will cover the «Shelter» object, a part of Unit В, southern and western pioneer walls, aswell as a part of currently existing SO local zone. Eastern gable will abut to existing structures of Plant,

Figure 25. General view of bearing structures of NSC casing.
- 51 -

western one will lean upon own foundation. Turbine hall will partially come forward through western wall.
General view of bearing structures of NSC casing is shown in Fig.25. Geometrical sizes of casing
make: span - 257,44 m, width - 150 m, height - 108,39 m, thickness -12 m.
In conformity with selected decisions, arched structure consists of bearing and fencing elements:• Main bearing elements are circular contour arches comprising a range of internal andexternal arches connected one to another by truss lattice (arched type trusses);• Fencing structures consist of two decks - outward deck (roofing) and internal (ceiling) deck,
which are attached to horizontal purlins fastened to arched truss girths.
Arched structure consists of 13 flat arches. Span between the flat arches makes 12,5 m.
NSC envisages the following systems providing NSC operation:• Dust suppression system;• NSC fire systems;• Ventilation systems;• Water supply systems;• Sewer systems;• Heat supply and conditioning systems;• Decontaminating solution supply system;• Compressed air supply system;• Power supply and electrical safety system;• Integrated NSC management system;• Communication and industrial television system;• Physical protection system;• Liquid and solid RAW management system.
Main parameters influencing the period of NSC building structures operation are as regards:• Radiation factors impact;• Corrosion factors impact.
In conformity with CD (FR) NSC, designed NSC operation term makes 100 years. Indicatedterm is reached due to:• consideration during design of extreme loadings and impacts in conformity with acting
regulatory documents;• application of materials with enhanced corroding resistance;• choice of optimal operation mode;• structural decisions providing maintainability.
NSC structure envisages a probability of subsequent change of roofing and wall panelsin operation period, which does not demand NSC partial opening. Change of panels will bemade using shielded platforms of technical maintenance hanged on rails inside and outside of NSC archmain elements.
Within the framework of CD (FR) NSC, strength estimates were made of NSC fencing structural
casing and foundations with considering the following external impacts associated with natural
phenomenon: seismic impacts; wind loadings; snow loadings; tornado loadings; air temperature changes;
lightning impact; precipitations.
In estimating, for seismic impacts the following values were taken:• Designed earthquake (one time per 100 years)- 5 numbers according to MSK-64 scale• Maximal estimated earthquake (one time per 10 000 years) - 6 numbers according to MSK64 scale.
- 52 -

For wind loading, the following values were used (in accord with SNiP 2.01.07-85 and PiNAE5.6):• Normative value of wind pressure - 0,3 kPa (30 kgc/m2);• Estimated loading - 0,42 kPa (42 kgc/m2),• Extreme loading -0,75 kPa (75 kgc/m2);• Reliability coefficient for loading-1,4 and 2,5 correspondingly for estimated andextreme loading.
For snow loadings, the following values were used (according to SNiP 2.01.07-85 and PiN
AE-5.6, as well as with considering historical climatological data based on repetition rate, one timeper 10 000 years):•
Normative value of snow cover weight - 0,7 kPa (70 kgc/m2);•
Estimated loading -1,0 kPa (100 kgc/m2);• Extreme loading - 2,1 kPa (210 kgc/m2);• Reliability coefficients for loading - 1,4 and 2,0 correspondingly for estimated andextreme loading.
For tornado loadings, estimate is made in conformity with «Main regulatory requirements
and estimated characteristics of tornadoes for Chernobyl NPP site», introduced by Order No 64 of
Ukraine’s Derzhbud of 21.10.2002.
In conformity with NP 306.1.02/1.034-2000, probability of realization of initial event, bringing toa need of public resettlement in case of exceeding estimated tornado class for newly designed objects ofnuclear power engineering should be established equal to Р=1·10-6 1/year, and for facilities underconstruction, operation and reconstruction - Р=1·10-5 – 1/year. Estimated characteristics of tornado withindicated probability for ChNPP site are shown in Table 9:
Table 9For tornado with
For tornado with
Estimated tornado characteristics
probability 1·10-5
probability 1·10-6
Estimated class of probable tornado
1.5
3.0
Exceeding probability, (event/year)
1·10-5
1·10-6
Maximal velocity of funnel rotation, (m/s)
5081
Velocity of tornado forward movement, (m/s)
12.6
20.3
Pressure difference between funnel centre and31.0
81
periphery, (gPa)
Length of tornado propagation path, (km)5.0
28.6
Width of tornado propagation path, (km)
0.05
0.29
For air temperature characteristics, the following values were used (according to SNiP 2.01.07-85):•

Normative temperature value:•

Estimated temperature value:••

Reliability coefficient for loading
Extreme temperature values (one time per 10 000 years) Minimum
Maximum

Minimum
Maximum
Minimum
Maximum-20°С;+26°С;-22°С;+29°С;
1,1;-43°С;+45°С.

Lightning impacts are expected at the level, under which is enough to have lightningprotection system meeting the requirements of PUE and «Instruction for arrangement of lightningprotection for buildings and structures (RD 34-21-122-87).

- 53 -

For maximal precipitation amount, the following values were used:• On average over 20-minute period - 31 mm;• Extremely over 20-minute period (one time per 10 000 years) - 72 mm;• Extremely during a day (one time per 10 000 years) -190 mm.
Strength estimates confirmed that realization of proposed constructive decisions would
provide the NSC stability under all considered external impacts associated with natural phenomena.
Particularly, stability of NSC main supporting structures and foundations under a class 3.0 tornado isconfirmed, and absence of a need, under such initial event, of public evacuation in conformity with
criteria of NRBU-97, NRBU-97/D-2000 and NP 306.1.02/1.034-2000.
When developing CD (FR) NSC, the following external technogenic impacts were considered:• explosion;• aircraft collapse;• fire;• initial events associated with existing ChNPP facilities.
Analysis of impact to NSC structures from explosion sources at the ChNPP site and behind its
limits has shown that under such initial events the loadings will be less of expectable by a tornado.
Aircraft collapse was excluded from consideration as a designed base due to following reasons:• In conformity with the national requirements of acting in Ukraine regulatory-legislative
documents, such initial event is not seen for the facilities for RAW and FCM management, towhich the SO is referred, and, correspondingly, the NSC;
• В ChNPP zone, organizing-technical measures accorded with appropriate bodies are envisaged,
which prevent aircraft flights;• Based on estimates performed in designing other ChNPP objects, probability of such initial
event evaluated at the level of 1·10-6/year. Existing estimates of probability of aircraft collapse
on a specified object for western-European countries, where aerial traffic is more intensive, thanin Ukraine, makes <10-7/year. In conformity with criteria, established in NRBU-97, such a rare
initiating event can be not considered.
• Use of this event as a design basis would lead to considerable unjustified increase in cost andmaking more complicated the NSC structures.
In CD (FR) NSC, aircraft collapse is seen as “out-of-design” event.
Analysis performed at pre-project development stage has shown, that additional impacts
influencing NSC design decisions are absent under external fires.
Analysis of initial events associated with existing ChNPP objects has shown, that ventilation
pipe VP-2 collapse on the NSC would lead to destruction of bearing structures of casement, and aprobability of such event is above, than it is admitted by acting regulations. In this connection, in CD (FR)NSC a conclusion is made on a need to dismantle ventilation pipe before the start of NSC pushing into
designed position.
Emergency situations at other ChNPP objects (LRTP, ПКОSRW, SNFR-1, SNFR-2) will not
provoke any additional loading on the NSC.
Main decisions for NSC erection technologies
Within the framework of CD (FR) NSC, main decisions were developed for such aspects oferection organization as regards: preparation of building territory, infrastructure for provision of
construction, possible erection technology is drafted.
- 54 -

Territory preparation works include clearing of building site, works for arrangement ofengineering mains at building site, works for planning territory at building site, organization of auxiliary
objects for construction.
Proposed in CD (FR) NSC infrastructure for provision of NSC construction must enable
delivery of tube and ferroconcrete structures, as well as of building materials, such as concrete, sand,fixturing, armature, etc. Besides, infrastructure must provide power supply, water supply, heat supply,
sewer (storm and household), and removal of producible RAW and construction waste.
In CD (FR) NSC, comparative analysis of construction technologies options is made. As aresult it was stated, that most preferable option is manufacture of section elements of arched structures at
Ukraine’s plants, their assembly beyond the site limits with subsequent delivery to assembly site.
Manufacture behind the site limits has a whole range of advantages, since plant-manufactures
are equipped with all appropriate infrastructures and possess opportunities to provide required quality
control, and considerable part of works will be performed beyond the limits of zone with high radiation
fields. On top of that, the amount of equipment, workforce and scope of work, performed at building site,
will be minimized.
Assembly of arched structure starts after installation of pushing ways, assembly site andinstallation of supporting units and bearing beds under the first supportable section. Structure will beassembled of individual 12.5-m wide sections. On top of that, two methods of arched structure assembly
are seen.
The first method includes the assembly of arched structure sections using crane with loadlifting capacity 1600 t and two cranes of less load-lifting capacity.
The second method is based on the point that assembly of arched structure sections is madewith using winch-hoisters. The both methods are real and technically realized, on top of that, the second
one permitting to perform more quantity of assembly works on earth level, that increases their safety andproductivity, is considered in CD (FR) NSC as a more preferable.
Pushing of arched structure (Fig.26) is made after installation of pushing ways, foundations
under arched structure, foundations of eastern and western gables, as well as completion of assembly ofpushing equipment and ventilation pipe dismantle. Most preferable pushing method and, according to CD(FR) NSC estimate results, is the pushing with applying tractive effort. This pushing method provides therequired friction coefficient and is more floppy due to possibility to change the amount of ropes andtowing jacks at each stage of arched structure pushing.

Figure 26. Modeling of arched structure’s pushing process to «Shelter» object.
- 55 -

After the arch is pushed in design position, completion of gables arrangement is made andsealing of arched structure. Connection of engineering mains and arched structure equipment can bestarted after pushing completion and assembly of equipment inside the NSC.
Management of RAW producible during NSC erection
Proposed in CD (FR) NSC decisions for RAW management under NSC construction are based on
the following positions:• For management of RAW producible during construction – existing at ChNPP RAW management
scheme will be maximally used;• In defining the decisions for management of RAW producible during construction - main
decisions и planned measures, developed within the framework of integrated program of ChNPP
RAW management are considered;• In defining the decisions for control and inventory of nuclear materials and RAW during
construction – it is adopted that this activity will be realized within the framework of system
existing at the SO;• Under NSC construction, only the RAW are subject to removal, which are located in building
work zones, for the rest RAW located in technogenic layer of local zone and SO industrial sitemust be provided possibility of their delayed removal during operation or dismantle of NSC.
During the NSC erection, the main RAW volumes will be produced by:• removal/displacement of on-land objects covered by construction zone (building structures and theirfragments, mains, construction waste, etc.) and cleaning of areas from shrubs etc.;• earthwork (crushed stone, ground, sand, concrete fragments, etc.);• drilling works (cores containing the above fractions).
SRW, producible under the NSC construction, according to contamination type will bepresented as both surface contaminated materials (large-sized fragments structures and buildings being
dismantled), and volumetrically contaminated (small-sized fragments and loose waste). Main
contamination of indicated materials is expected by radionuclides of 137Cs, 90Sr, 239+240Pu, and 238Pu, 241Am,
which will determine gamma-radiation EDR, surface and volumetric contamination rate.
As volumetrically contaminated SRW the high-level waste (HLW) are expected, which
can be presented as fragments of negligible sizes (active core fragments and strongly contaminatedconcrete fragments). The rest SRW will be referred to low- and intermediate-level waste (LIL SRW), ofpredominantly 1 category low-level waste).
During works for removal/displacement of existing mains, removal around 1300 m3 of groundis expected, which received radioactive contamination as a result of 1986 year accident, in which can
include the impurities that due to contamination level are referred to SRW 3 category. Performed in CD(FR) NSC estimate of volumes of technogenic layer demanding removal have demonstrated that during
creation of NSC foundations, up to 82500 m3 ground can be excavated. It is assumed that the volumeof SRW 3 category (HLW) during earthwork would make around 120 m3.
When preparing internal sites under arched structure, additional ground can be excavated involumes of 24170 m3 (for the most, with contamination at background level values).
General scheme of radioactively contaminated ground management includes two level of theirsorting:• primary sorting according to ground removal place with the purpose:- primary identification and HLW segregation using the criterion «EDR of extractableground»;- dividing the rest waste into small-sized and large-sized;- 56 -

• detailed ground sorting at a specially arranged site with the purpose to divide into the waste subject
to burial and, the waste that can be used for backfilling during erection of foundations.
The grounds having high contamination level will be forwarded to interim monitoring point forcertification, and from that place they will be transferred for long-term storage/burial:• to PLRW «Buryakivka»,• to industrial complex for handling solid radioactive waste (ICSRW) - after its commission.
Large-sized LIL SRW meeting the burial acceptance criteria, after surfaces dust strengthening canbe transported directly to PLRW « Buryakivka » or to ICSRW.
To provide the fulfillment of above works, the sites for waste removal and management
envisage the following equipment and facilities:• specially equipped machinery with attached equipment for handling radioactively contaminatedmaterials;• specially equipped site for ground segregation into categories;• check points with dosimetric control;• stations for decontamination of RAW management machinery and equipment.
In order to reduce radioactive substance concentrations in the atmosphere in work production places,
use of dust suppression is envisaged.
Nuclear safety provision
Under normal conditions of NSC construction, to provide nuclear safety of CD (FR) NSC isenvisaged:• not to worsen the conditions of atmospheric precipitation discharge from existing SO roofing;• not to create additional apertures in SO roofing, as well as other ways for incoming atmosphericprecipitation in premises, where nuclear hazardous FCM clusters are localized;• not to worsen conditions in part of condensation moisture production as compared to existing
conditions;• not to realize technical decisions, which could change existing water flows system inside the SO
and contribute to moisture accumulating in nuclear hazardous zones;• not to worsen the conditions for functioning of current system for collection and removal of SO
radioactively contaminated water;• exclude the use of technological waters when performing work at the sites adjoining to SO nuclear
hazardous zones ;• exclude conditions violating efficiency of existing system for nuclear safety monitoring:- information-measuring system (IMS) «Finish-Р»;- FCM monitoring systems (MS FCM) «Signal»;• to go on maintaining FCM in subcritical condition in volume established by acting SO
technological regulation, using the existing systems:- system for supply of nitric gadolinium solution;- facility for operative insertion of neutron-absorbing solution;- dust suppression systems (in mode of neutron-absorbing solution supply).
• to realize organizing measures for nuclear safety provision in conformity with acting SO
technological regulation.
During NSC construction, to reduce SCR generation risk in emergency situations occurred as aresult of SO building structures collapse, CD (FR) NSC envisages as follows:• Measures for stabilization of SO building structures will be performed before NSC- 57 -

construction start, that will result in reducing collapse risks to acceptable level;• NSC structures will be designed in conformity with criteria и requirements of nuclear and radiation
safety;• Considerable part of building and assembly works will be performed at safe distance from the SO,
which excludes direct mechanical impact to it;• Building and assembly works in close vicinity from the SO, including NSC pushing, will be
realized with applying technologies and technical means с high reliability indices;• For fire extinguishing in nuclear hazardous zones is assumed using of water-free compositions
and/or aqueous compositions with neutron-absorbing additives;
As a whole, during NSC construction (in normal conditions and in emergency situations)with considering envisaged measures, nuclear safety will be provided at the level existing for operated
SO. When the NSC will be commissioned, SO nuclear safety level will be essentially improved.
Radiation safety provision
Availability of radioactive materials in the SO defines potential radiation hazard of all activity
for SO conversion into an ecologically safe system, including activity in NSC design scope. In CD(FR) NSC, measures for provision of radiation safety were prepared with considering the fact that
NSC construction and operation will be realized as activity with open ionizing radiation sources.
During NSC design realization, radiation conditions will be defined by:• availability of radioactive substance in work production zones;• radiation background created by SO;• radioactive aerosols release from SO;• direct activity (dust rise, RAW management, including FCM).
To provide radiation safety, CD (FR) NSC envisages at all stages of NSC design realization:• organizing measures;• technical measures;• sanitary-hygienic measures.
Organizing measures, which are common for all stages of NSC design realization, include:• personnel training;• planning of work; organization of safe work production;• control and supervision.
As designed reference levels of individual exposure of personnel and radiation conditions for all
the stages NSC design realization, CD (FR) NSC takes the values established currently at the SO.
During NSC construction, the main technical measures providing radiation safety will include as
regards:• protection with distance;• shielding;• dust suppression.
Protection with distance implies minimization of works being performed close to SO, especiallyon high marks, for the above the CD (FR) NSC envisages the following decisions:• Part of labor-intensive work will be carried out beyond exclusion zone limits;• Assemblage of NSC building structures and a range of its technological system will be
realized at a far distance from SO (150 m);• Structures assembly procedure envisages their assemblage on earth level.
Shielding of work production zones will be provided by application of:• protective boxes;• relocatable shields;- 58 -

• shielded attached or traveling platforms;• shielding of operator cabins for technical means.
Measures for short-term dust suppression (damping with water) will be carried out underprobable increase of dust rise in work zone during work production, or personnel movement. Longterm dust suppression (laying of localizing compositions) will be carried out in case of need to
localize radioactive contamination (dust-strengthening) on surfaces of transportable large-sized
structures and other elements without containerization.
Dosimetric control during construction includes as regards:• monitoring of radiation conditions, which provides:- EDR monitoring;- monitoring of contamination levels by radioactive substances of work surfaces of premises,
equipment and vehicles;- monitoring of volumetric activity of radioactive substance in work zone air;- radiation control at all RAW management stages;• individual dosimetric control (IDC) of personnel including:- IDC of external exposure due to beta- and gamma-radiation with application of individual
dosimeters;- IDC of internal exposure, which is made on the basis of data of direct and indirect
biophysical measurements;• system of operative and long-term planning, inventory and storage of data on individual
personnel exposure doses.
Collective effective dose of personnel during NSC construction, preliminary evaluated in CD(FR) NSC with considering realization of indicated measures, made - 450 men-Sievert. It is assumed
that realization of organizing and technical measures according to ALARA principle can reduce thisvalue to -250 men -Sievert. The above estimate is subject to more precise definition at the stage ofdetailed design during preparation of Work Production Project (WPP).
Assessment of impacts to components surrounding natural environment
During the works over CD NSC design, estimates of impacts of activity under design tosurrounding natural environment were made.
Impacts to aerial medium
As a result of performed estimates, for emergency situation scenarios under consideration thefollowing impact levels were established:• value of radioactive releases penetrating into atmosphere, under condition of SO collapse without
NSC, makes around 1,59·1013 Bq;• value of radioactive substance releases, under condition of SO collapse inside NSC, will makefrom 8,49·1010 to 8,08·1011 Bq depending on SC ventilation conditions (from 0,1 to 1 SC volume
a day).
Impacts to soils
Under normal conditions of NSC design realization, impact to soils from SO aerosol releases
precipitation till construction completion will be preserved at existing level, negligible as compared toradioactive contamination occurred in the first months after 1986 year accident.
After NSC commission, release amount will reduce.
Under emergency situations, the most soil contamination is predicted in case of base option (SO collapse
without NSC) and first option (SO collapse during NSC pushing), under extraordinary meteorologicalcondition (atmosphere stability category on Pasquill F, wind velocity - 1 m/s). On top of that, maximal(along plume central axis), surface contamination values at 10-km distance (additionally to existing- 59 -

contamination) will make from 5% to 60% of existing contamination of ChNPP exclusion zone
soils at given distance.
At the boundary of ChNPP exclusion zone, maximal (along plume central axis), additional surface
contamination will make from 30% to 100% of existing contamination of soils at the boundary of ChNPP
exclusion zone.
Beyond ChNPP EZ limits, at 50-km distance, maximal (along plume central axis)
additional surface contamination will make:• with radionuclide 137Cs - 3,2 104Bq/m2;• with radionuclide 90Sr- 2,8 104Bq/m2;• with radionuclides 238+239/40Pu - 6,5 102Bq/m2,
that will exceed existing levels in several times.
For SO collapse inside NSC option, maximal soil contamination under analogous
meteorological conditions is forecast in dozen-hundred times less (depending on NSC ventilation mode) as
compared to contaminations under SO collapse without NSC.
Maximal summary (for all radionuclides) additional surface contamination at 10-km distance isforecast at level of 1,7 104 Bq/m2 that makes not more 2% of existing contamination of ChNPP EZ soils
at given distance.
At the exclusion zone boundary, maximal summary surface contamination is forecast at level3
3,3·10 Bq/m2 that makes not more 10% of existing contamination.
Impacts to water medium
Under normal conditions of NSC design realization, impact to surface water from SO aerosol
releases precipitation before the completion of construction will be preserved at existing negligible level.
After NSC commission, SO releases amount will reduce.
Under emergency situations, impact to surface water will be defined by direct atmosphericprecipitation on water surface of river Prypyat, as well as precipitation on its flood plain close to
NSC with subsequent radionuclides outflow from drainage areas. Forecast of emergency
contaminations of surface waters performed in the EIAR covers Kyiv, Kaniv, Kremenchuh and Kakhovka
reservoirs. The largest aftermath are forecast in SO without NSC collapse and SO collapse during NSC
pushing.
The biggest peak of 90Sr concentrations in water is forecast for 41 day after the accident, and forboth options of emergency situation will make:• for Kyiv reservoir (Kyiv SPP) - 684 Bq/m3;• for Kaniv reservoir - 389 Bq/m3;• for Kremenchuh reservoir - 225 Bq/m3;• for Kakhovka reservoir - 178 Bq/m3.
The maximal value of presented above (for Kyiv reservoir) makes 34% of admissible 90Sr
concentrations in drinking water.
The maximal 137Cs concentration under basic and first options in Kyiv reservoir makes 455 Bq/m3, in
Kaniv reservoir - 137 Bq/m3 (correspondingly 32% and 11% of admissible 137 Cs concentration in
drinking water). Maximal concentration of Pu, 23 Pu and 41 Аt forecast for Kyiv reservoir, does notexceed 1 Bq/m3 for each radionuclide.
For SO collapse under NSC option, level of radionuclides income depends on NSC ventilation
conditions. Under ventilation equal to 1 NSC volume a day, maximal increase of 90Sr and 137Csconcentrations as compared to background level makes 25% and 91% correspondingly (11% and 2% ofadmissible concentrations for drinking water). Under ventilation equal to 0,1 SC volume a day, 90Sr andCs concentrations will be an order less, and annual concentrations will be only at 0,3% exceed thebackground values of indicated radionuclides content in Kyiv reservoir water.
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Simulation of impacts to underground water is made in the EIAR with considering the fact that themain contamination source is water infiltration from SO premises 001/3. On top of that, radionuclides
transporting by underground waters was considered independently of current contamination ofunderground waters conditioned by other sources (surface contamination, burial sites near the SO,etc.).
For 90 Sr possessing the biggest migration capacity, the following results were obtained:• Under scenario of SO collapse without NSC, concentration in underground waters, exceeding 4109 Bq/m3, will be observed at less 100-meters distance, 1·102 Bq/m3 level will be provided yet at
600-m distance from the SO. Contamination field will reach river Prypyat after 800 years, on topof that, 90Sr concentration, because of radioactive decay, will drop at 5,7·10-9 fold of initial values.
• by SO collapse under NSC, 90 Sr concentration in underground waters will be reduced,
practically, to zero.
Assessments of impacts to geological medium and climate, which were described in the EIAR atconceptual level, has shown the absence of some significant impacts to these medium components.
In connection with existing high contamination level of ChNPP EZ territory, a conclusion ismade in EIAR on the fact that impact to flora, fauna and reserved objects within the limits of thisterritory will be weakly distinguished even under base option of emergency situation (SO collapse
without NSC). On top of that, extremely restricted atmospheric transport and availability of backgroundcontamination of flora and fauna makes negligible emergency impacts behind the ChNPP EZ limits.
Estimate of mutual impacts of NSC and objects of surrounding technogenic medium
As a result of performed impacts analysis, it was defined as regards:• impacts of emergency situations at LRTP, ICSRW, SNFR-1, SNFR-2 will not entail any additionalloading to the NSC;
• unfavourable impact of collapse of existing ventilation pipe of power Unit 4 is ruled out, since it(pipe) is being dismantled. Newly erected pipe will be designed for extreme impacts. On top of
that, in conformity with NSC construction schedule, existing ventilation pipe must be dismantled
before starting NSC pushing works.
Under normal conditions of NSC design realization, its impact to surrounding technogenic
medium will be expressed in displacement of existing life support systems of the SO and ChNPP
Unit 3 (electricity supply networks, systems of water supply and household sludge sewer, etc.) located at
NSC construction site.
Assessment of impacts to social environment
Realization of NSC design will positively impact to social environment in several fields:• it will essentially reduce the risks of public exposure under emergency situations at the SO;• it will reduce psychological tension in society associated with SO collapse treat;• it will provide employment for part able-bodied public of towns of Slavutich, Chernihiv and othersettlements;• it will provide loading of Ukraine’s industrial enterprises during manufacture of NSC structures andcomponents.
Measures for minimization of environmental impacts
NSC creation, in itself, is a measure aimed at minimization of SO environmental impacts, since
NSC availability will allow:• isolate RAW located in SO;• reduce probability of nuclear incidents due to exclusion of atmospheric moisture penetration on FCM
clusters inside SO;• perform works for handling FCM and RAW under protective casing.

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Minimization of negative environmental impacts during NSC construction will be achieved bymeans of realization of following technical and organizing measures:• dust suppression in earthwork production places;• dust strengthening;• decontamination of applicable mechanisms and vehicles;• application of technologies with minimal dust rise;• organization and control over RAW transporting and management.
Minimization of negative environmental impacts during NSC operation in the course of
dismantling unstable SO structures will be reached by means of realization of the following technicaland organizing measures:• Arrangement of ventilation system, with using aerosol filters for exhaust air cleaning;• Zoning of NSC territory and premises;• Dust suppression in work production places;• Organization of radiation control system;• Decontamination of vehicles leaving the NSC limits;• Use of revetment of premises, where radioactive substance release into premises is possible;• Organization of building structures control system;• Restriction and control of NSC discharges and releases.
Estimate of potential exposure
In CD (FR) NSC, analysis was made of potential exposure of personnel and public as a resultof realization of activity associated with NSC construction and operation, and substantiation of nonexceeding of exposure risk criteria defined in NRBU-97/D-2000 was made.
Estimate of potential exposure during NSC construction
In CD (FR) NSC, the following emergency situations during NSC construction are seen, which
can lead to potential exposure of public and personnel:• SO fire due to error of personnel/failure of equipment during NSC construction before pushing
NSC arch;• SO collapse due to error personnel/failure of equipment during NSC construction before pushing
NSC arch;• SO collapse due to extreme wind during NSC construction before pushing NSC arch.
Fire at the SO due to error of personnel/failure of equipment during NSC construction before
pushing NSC arch can occur as a result of the following initial events:• ignition of materials during the welding;• ignition of electrical equipment;• vehicle accident in local zone.
When assessing potential exposure under a fire at the SO, the following assumption and initial
data were applied:• It is assumed that as a result of fire no SO collapse occurs;• Total release during origination of fire at the SO makes 4,8·1010Bq;• Fire duration makes 4 hours;
As a result of estimates it was stated that individual effective dose under a fire for nonprotected personnel close to SO makes around 12,6 mSv.
At a distance from SO under given initial event, maximal individual dose is formed at around
10-km distance and makes - 7·10-3 mSv. Thus, release influence under a SO fire to personnel locatedat far distance from the SO, will be negligible.
Dose of public at the ChNPP EZ boundary makes 4-10-3 mSv.

- 62 -Collapse of SO building structures, due to error of personnel/failure of equipment during
NSC construction before pushing NSC arch, can occur because of collapse of assembly crane or loadon the SO.
In conformity with existing models, volume of SO aerodynamic shadow was estimated around 106 m3. Thus, conservatively assuming that all activity precipitates in aerodynamic shadow
zone, radioactive substances concentration in air makes around 7,79·106 Bq/m3. Cloud existence time
is taken as equal to time, during which the wind will pass distance equal to aerodynamic shadow
length. Under wind velocity of 3.3 m/s, this time is equal to 45 s. Over this time, individual effective
dose for non-protected personnel, close to the SO, makes -58 mSv.
At a more far distance from the SO, maximal individual dose is formed at 1-km distance andmakes around 4 mSv. Thus, inhalation dose for personnel located at a bigger distance from the SO
will be significantly less, than the above dose close to the SO. Dose for public at the ChNPP EZ
boundary makes 0,1 mSv.
Estimates of potential exposure during NSC operation
To estimate potential exposure during NSC operation, the following emergency situations under
NSC operation are seen, which can lead to potential exposure of public and personnel:• SO fire under essential reduction of fire protection due to personnel error under NSC operation;• SO collapse due to earthquake with loss of power supply during SO structures dismantle and
NSC operation;• impossibility to close NSC transport gate due to error of personnel/failure of equipment during SO
collapse.
Potential exposure in case of realization of indicated emergency situations is associated withinhalation intake of radioactive aerosols into organism. The source of aerosols origination is a fire or
SO collapse. Since these critical events occur after NSC arch is pushed on its place, therefore, producible
aerosols are scattered inside the NSC. Eventually, a part of aerosol materials comes into environment, theremained materials precipitate inside the NSC. Reduction of radioactive substance release is provided
due to shut off of arched space ventilation. It is evident, that maximal individual dose of potential
exposure for personnel staying inside the NSC is essentially higher, than for the personnel being outside
the NSC.
Fire at SO under and essential reduction of fire protection due to personnel error during NSC
operation can occur as a result of the following initial events:• ignition of materials in the course of welding;• ignition of electrical equipment;• vehicle accident inside the NSC.
In estimating potential exposure by an SO fire, the following assumption and initial data are used:• It is assumed that as a result of fire, no break of NSC structures integrity will occur;• Total release during SO fire origination inside the NSC makes 4.8·1010 Bq [2].
• Fire duration makes 4 hours;
Maximal individual dose of potential exposure will be received by personnel located inside the
NSC due to radioactive aerosols inhalation, on top of that, inhalation time makes 1 hour (it is assumed
that the fire was detected and the personnel was evacuated through 1 hour after origination of strong fire,that is a sufficiently conservative assumption).
Results of estimate have shown that over the time needed for evacuation, maximal
individual dose of potential exposure for non-protected personnel inside the NSC makes around 11,3
mSv. Considering the fact that the personnel in NSC will work in IPGRO, or in isolated premises, real
dose is forecast at least at order less – 1,1 mSv.
Release from the NSC will make 2·108 Bq.
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Maximal individual dose outside the NSC makes around 4·10-4mSv. Evidently, that inhalationdose of potential exposure of personnel inside the NSC is essentially less of dose inside the NSC.
Dose of public at the boundary of ChNPP EZ makes 3·10-8 mSv.
Under SO collapse due to earthquake with loss of power supply during SO structures dismantle
and NSC operation, the estimates made have shown as regards. During loss of power supply, failureof NSC control systems can occur, which will entail the event when ventilation system shutters canremain in open position. The above brings to increase of air exchange with surrounding environment to200% NSC volume per a day and relevant accelerated drop of radioactive aerosols concentrations inside
the NSC.
When estimating potential exposure dose, the following assumptions and initial data are used:• Under earthquake, no NSC structures destruction will occur;• Total release under collapse of SO structures building inside the NSC makes 7.79-1012 Bq:
Maximal individual dose of potential exposure will be received by the personnel located inside
the NSC due to radioactive aerosols inhalation; on top of that, inhalation time makes 20 min (maximal
time needed for emergency evacuation of worker);
Over the time needed for evacuation, maximal individual dose of potential exposure of
personnel inside the NSC makes 44 mSv. Under an essentially more probable particular collapse, the dose
makes around 15 mSv.
Release beyond the NSC limits will make 8,4·109 Bq. Maximal individual dose of personnel
outside the NSC will make around 3 mSv (under partial collapse - around 1 mSv). Evidently, that
inhalation dose of potential exposure outside the NSC is much more less than the dose inside NSC.
Dose for public at the ChNPP EZ boundary makes around 10 mSv.
Conclusion
Choice of all principle technical decisions for NSC is confirmed by estimated substantiations
performed within the framework of CD (FR) NSC. Particularly, estimated substantiation are made fordifferent options:• mode of NSC thermal isolation and ventilation;• arched structure configuration;• structural decisions on foundations, et al.
For NSC structure being proposed in CD (FR) NSC, strength estimated substantiations arecarried out, which confirm NSC stability under extreme values of different loadings and their
combinations. Particularly, stability of supporting structures and NSC foundations is confirmed under aclass 3.0 tornado.
In CD (FR) NSC, assessment of environmental impacts during NSC design realization ismade. It is shown that under normal realization of design and in emergency situations, “Shelter” object’s
environmental impacts have essentially smaller aftermath, if the NSC is available, as compared toabsence of fencing casing.
In CD (FR) NSC, potential exposure of personnel and public as a result of realization of activity
associated with NSC erection and operation is evaluated, and non-exceeding of exposure risk criteria issubstantiated, which is defined in NRBU-97/D-2000.
As a whole, in CD (FR) NSC at conceptual level, probability of achievement of set objectives in
NSC creation is demonstrated, which are as follows:• providing protection of personnel, public and environment from the influence of sources ofnuclear and radiation hazard associated with the SO existence;- 64 -

• providing conditions for realization of activity aimed at SO conversion into an ecologically safe
system, including that for dismantling/strengthening unstable SO structures, FCM extraction and RAW
management.
List of references
1. Law of Ukraine «Of ratification of United convention of safety under spent fuel management and ofsafety under radioactive waste management «, No1688-111 of 20.04.2000.
2. Law of Ukraine «Of ratification of Convention of nuclear safety», No 736/97-ВР of 17.12.1997.
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countries and Commission of European Commonwealth in relation to Chernobyl NPP decommissionof 20.12.1995.
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11.12.1998.
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system» No 1561 of 28.12.1996.
15. Decree of Ukrainian CM «Of approval of Shelter Implementation Plan» No 421 of 31.03.2003.
16. Strategy of «Shelter» object conversion approved by decision of Government Commission for issuesof complex solution of Chernobyl NPP problems. No 2 of 12.03.2001.
17. NRBU-97. Norms of radiation safety of Ukraine. State hygienic regulations. Ukraine's HM (1997).
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and requirements in relation to application order (NRBU/ОСПУ). State sanitary rules. Ukraine's HM(2002).
19. NRBU-97/D-2000 Norms of radiation safety of Ukraine. Supplement: Radiation protection frompotential exposure sources. Ukraine’s HM (2000).
20. DBNA.2.2-3-97. Content, order of development, agreement and approval of design documentation for
construction, (1997).
21. DBN А.2.2-1-95. Composition and content of materials for environmental impacts assessment (EIAR)
under design and construction of enterprises, buildings and structures. Main designing principles,(1995).

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