MONITORING OF RADON ²
² ²Rn AS AN INDICATOR OF POSSIBLE TECTONIC EVENTS AT NPP
Ulyanov V.Y ., Haidabas I.M.,
"Pridneprovsky Research and Educational
Institute of Innovative Technology in Construction"
article shows the organization and monitoring of radon areas of energy
radon, radon monitoring, radon station seismic tectonics.
anomalies as potential indicators of strength of the lithosphere.
Our planet as a dynamic structure
in the case of unloading has the stress-deformation state at numerical points.
One of its characteristics in the seismically active regions of the Earth is
demission abnormally high concentrations of deep gas into the atmosphere. In non-seismic
areas we also notice stress-deformation state of the Earth which is expressed
in periodic variations in the intensity of free gases' flow into the atmosphere.
At the same time regardless of the intensity of gases' flow the centers of
their unloading space remain unbiased. Along with composition of methane,
hydrogen and helium, gas stream which is freely discharged into the atmosphere,
commonly establishes the presence of an inert gas - radon (² ² ²
Rn). Its physical and radiometric properties: inertia, short half-life (3.82
days), presence of decay products ( metal isotopes) serve as the basis for its
study and use as an indicator for establishment of the deconsolidation of the
Ruptures in the crust are one
of the main sources of environment imbalance. Thus, ruptures are characterized
by a long history of development with numerous, up to date, activation stages.
These ruptures have influence on the formation of the surface relief. Zones of
ruptures are characterized by an increased fracture, disintegration and water
Along them actively developed
karst observed intense mounted hydraulic between surface water and groundwater.
Karst is actively developing along them, while there are intensive water flows,
and hydraulic exchange between surface water and groundwater is set. As a
result of all these phenomena we observe decompression and bearing soil
subsidence in the areas of dynamic influence of ruptures, as well as
infiltration of surface contaminants in aquifers and drinking purposes. In addition
we notice formation of landscape anomalies with high concentrations of chemical
elements and substances of different hazard classes on geochemical barriers.
Also deformation of the earth surface in the zones of influence of faults is
often met and that leads to violations of the integrity of the buildings,
roads, pipelines, including structures and critical facilities (NPP, power
Formation of radioactive radon
gas anomalies in the overburden above the ruptures served as the theoretical
basis for the application of emanation (radon) survey to map rupture
dislocations in closed areas. In the 70s of the last century it has been found a
new phenomenon: a direct relationship between the intensity of radon anomalies
with geodynamic processes in the Earth's crust and in rupture zones. This
phenomenon was the basis of a new direction of research in geology - structural-geodynamic
Based on the above, the
behavior of ² ² ²Rn in geological space creates conditions for
its continuous monitoring as an indicator of the stress state of the
lithosphere. This is confirmed by abnormally high concentrations of ²
² ²Rn in the periods prior to the earthquake, as well as unintended
emission of gases in coal mines, the change in intensity of the atmospheric
electric field and geological array before landslide processes and many other.
Last time, radon as an
indicator of tectonic events is in the focus, particularly in the framework
created around the plants in Russia, Ukraine and other countries of the
so-called geodynamic polygons where initiated and actively carried out
high-precision geodetic and seismological studies are carried out. They include
complex specialized radio hydro geochemical studies that meet the requirements
of normative documents .The works in this direction have received additional
impetus after the events at the Japanese nuclear power plant
2. Radon ² ² ²Rn
Monitoring as a factor of safety of nuclear power plants.
In order to avoid the effects
of seismic events which took place in the Japanese nuclear power plant
"Fukushima-Daiichi" existing at NPP systems need to expand and
complement the new system - monitoring of radon ² ² ²Rn, which
actually have to be re-created. The results of these studies show that in high
seismicity areas, the system may well be successfully implemented.
The main difference between the
data from the monitoring radon monitors of another data type, which records
numerical value (e.g., electrical resistivity, seismic activity, etc.) is not
registered only as a radon activity concentration value (SAR) at the given
point in a given time but its change in time. In this case, you can judge the
change in the stress-strain state (compression or tension). Observed time of
earthquake preparation is sufficient to determine the behavior of the SAR and,
accordingly, the nature of the lithosphere deformation unit (tension or
compression). Thus, there is continuous monitoring of the change of the
stress-strain state in the preparation of a tectonic earthquake. These changes
were clearly shown on the curves of SAR derived from monitoring data.
Advantages of radon monitoring
over conventional seismic monitoring is as follows:
a) radon monitor is placed directly in the test
block of rock, which significantly improves the signal to noise ratio when
b) monitoring of radon signal gives the dynamic indication
of the stress-strain state of rock unit (compression-tension);
c) the rate of dynamical processes during
earthquake preparation is relatively small, that allows to handle the
monitoring data in real time.
This system is an absolutely
essential, given the ever-increasing impact of even small seismic events in the
state of NPP constructions, especially erected in the 70 - years of the last
century. It should be noted that the proposed system is intended for use by the
plant operation. Operation of the system components at first is assumed in a
partially continuous mode, and in the future it will be proposed for a fully
automatic one. The method of operation of the proposed system is quite simple
in execution. Measurements are reduced to the simultaneous continuous automatic
recording of SAR in the soil air at specially selected NPP sites using
so-called automatic radon stations. The same applies to the SAR groundwater
samples, including pumped regime selected wells. It also may be applied to
drainage wells (assuming plant operation in continuous dewatering). The
presence of other elements or chemically active media does not interfere. To
register radon is used at first serial instrumentation. Radiation safety in
normal conditions is achieved by using relatively low concentrations of tracer.
This process does not require special security measures, as well as
3. Machinery and equipment.
In the early stages of
monitoring determination of radon in water samples is expected to produce in
the laboratory directly to the site of the existing of NPP in the chemical
laboratory staff. Samples are collected manually from the output lines and
drainage wells in the trunks of selected monitoring wells. This is a difference
from the definitions of radon in soil air determined automatically called radon
stations. This is due to the fact of the absence of domestic equipment for
continuous registration of radon in groundwater (wells), as well as equipment
for the continuous registration of radon flow (waste waters) at NPP. The reason
is that the direct continuous automated measurement of radon in flowing waters
is a rather complicated technical problem related to the singularities of the
radioactive gas, its inertness and low half-life.
In the initial stages of radon
monitoring at the NPP site is proposed to use a batch laboratory equipment
produced in Russia, for example, such as:
- measurement system for monitoring of radon,
thoron and their daughter products “Alpharad plus”;
- gamma beta and alpha spectrometer
- radiometer MKGB-01 RADEK;
- seismic station radon CDS-05 of domestic or
foreign counterparts . In the long term it will be necessary to equip the
selected water by automated systems with continuous measure of radon content in
flow (waste) water if necessary.
1. The main purpose of the
proposed system of research is to identify and study the possible relationship
between the degree of enrichment of groundwater radon depending on openness of
geologic structures, groundwater circulation conditions and hydrodynamic zoning
and general seism tectonic conditions at the site location of the NPP.
2. Application radon metric
down hole in conjunction with geophysical methods is useful when studying
complex fault-block tectonics of the crystalline basement rocks for the
possibility to activate it. These studies, in accordance with regulatory
requirements, should be part of the so-called hydro geodesic formational monitoring
together with high-precision geodetic observations and borehole seismometer.
3. Qualitative methodology
consists in conducting a thorough and comprehensive analysis of the results
produced by parallel measurements of permanent SAR in the soil air using an
automatic radon station type CDC-05 as well as permanent SAR measurements in
water samples, preferably from permanent drainage wells and deep regime wells.
4. At the initial stages of
radon monitoring treatment of water samples from wells regime and drainage
wells can be produced in the laboratory directly to the NPP sites. Subsequently
it will be possible to install automated systems for the continuous
determination of radon in water (drainage wells and wells continuous) in the
case of their design and creation.
5. However, the widespread
introduction of borehole radon metrics and radon as an indicator of tectonic
activity is for sometime hampered by lack of commercially manufactured portable
field borehole instrumental systems for continuous automated determination of
radon ² ² ² Rn in water wells, including self-emission and
drainage. Currently manufactured equipment for determining radon in water is
only a laboratory one, and for this reason it is difficult to use it for
monitoring purposes. It cannot be considered acceptable, especially given the
availability of the widest range of standard equipment for the determination of
radon in the soil air.
6. Another limiting factor is
that the procedure for determining of radon sample until now is not clearly
defined, and the system of normative references ignores the specificity of the
aggregate radon state. Thus it is difficult to provide water quality sample
points for different purposes (in the first place at drainage flowing wells)
for radon, especially in complex geological and hydro geological conditions.
7. However, even though the
temporary availability of certain difficulties listed above, radon monitoring
system, if implemented, could significantly contribute to safe operation of
nuclear power plants, especially in complex seismic tectonic conditions.
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