Empirical analysis of Chernobyl nuclear reactor core for 5 seconds before the explosion
This study uses the methodology of empirical analysis for analyzing the transient mode of the nuclear reactor core, a few second before the explosion at the time of the Chernobyl accident. The parameters were selected from the published articles [1]. A scenario was assumed for this analysis, such as...
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Навчально-науковий комплекс "Інститут прикладного системного аналізу" НТУУ "КПІ" МОН та НАН України
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| Цитувати: | Empirical analysis of Chernobyl nuclear reactor core for 5 seconds before the explosion / Y. Matsuki, P.I. Bidyuk // Системні дослідження та інформаційні технології. — 2016. — № 3. — С. 33-41. — Бібліогр.: 2 назв. — англ. |
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Digital Library of Periodicals of National Academy of Sciences of Ukraine| _version_ | 1860222704734437376 |
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| author | Matsuki, Y. Bidyuk, P.I. |
| author_facet | Matsuki, Y. Bidyuk, P.I. |
| citation_txt | Empirical analysis of Chernobyl nuclear reactor core for 5 seconds before the explosion / Y. Matsuki, P.I. Bidyuk // Системні дослідження та інформаційні технології. — 2016. — № 3. — С. 33-41. — Бібліогр.: 2 назв. — англ. |
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| container_title | Системні дослідження та інформаційні технології |
| description | This study uses the methodology of empirical analysis for analyzing the transient mode of the nuclear reactor core, a few second before the explosion at the time of the Chernobyl accident. The parameters were selected from the published articles [1]. A scenario was assumed for this analysis, such as the reduction of the flow rate of the Main Circulation Pump, and regression models were constructed to examine this scenario. The results of the models application were examined, and conclusions were made regarding the reduction of the flow rate of the Main Circulation Pump and the reactivity during the last few seconds to the explosion.
У дослідженні використоно методологію емпіричного аналізу для вивчення перехідних процесів активної зони ядерного реактора за кілька секунд до вибуху під час аварії на Чорнобильській АЕС. Параметри вибрано з опублікованих робіт [1]. Сценарієм цього аналізу передбачено зниження швидкості потоку основного циркуляційного насоса та побудовано регресивні моделі для вивчення цього сценарію. Розглянуто результати застосованої моделі і зроблено висновки про зменшення витрат головного циркуляційного насоса та реактивності протягом останніх кількох секунд до вибуху.
В исследовании использована методология эмпирического анализа для изучения переходных процессов активной зоны ядерного реактора за несколько секунд до взрыва во время аварии на Чернобыльской АЭС. Параметры выбраны из опубликованных работ [1]. Сценарием этого анализа предположено снижение скорости потока основного циркуляционного насоса и построены регрессионные модели для изучения этого сценария. Рассмотрены результаты примененной модели и сделаны выводы об уменьшении расходов главного циркуляционного насоса и реактивности в течение последних нескольких секунд до взрыва.
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| first_indexed | 2025-12-07T18:18:31Z |
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Yoshio Matsuki, Petro I. Bidyuk, 2016
Системні дослідження та інформаційні технології, 2016, № 3 33
TIДC
ПРОБЛЕМИ ПРИЙНЯТТЯ РІШЕНЬ
І УПРАВЛІННЯ В ЕКОНОМІЧНИХ, ТЕХНІЧНИХ,
ЕКОЛОГІЧНИХ ТА СОЦІАЛЬНИХ СИСТЕМАХ
UDC 519.004.942
DOI: 10.20535/SRIT.2308-8893.2016.3.03
EMPIRICAL ANALYSIS OF CHERNOBYL NUCLEAR REACTOR
CORE FOR 5 SECONDS BEFORE THE EXPLOSION
YOSHIO MATSUKI, PETRO I. BIDYUK
Abstract. This study uses the methodology of empirical analysis for analyzing the
transient mode of the nuclear reactor core, a few second before the explosion at the
time of the Chernobyl accident. The parameters were selected from the published ar-
ticles [1]. A scenario was assumed for this analysis, such as the reduction of the flow
rate of the Main Circulation Pump, and regression models were constructed to ex-
amine this scenario. The results of the models application were examined, and con-
clusions were made regarding the reduction of the flow rate of the Main Circulation
Pump and the reactivity during the last few seconds to the explosion.
Keywords: Chornobyl disaster, critical operation mode, regression analysis, void
and water environment
SCOPE OF ANALYSIS
On 26 April 1986, an explosion occurred in the nuclear reactor core of Chernobyl
Power Station, Unit No.4. It is known that the specific design of the reactor core
was one of the main causes of the accident. This research analyzed the relations
between the sudden reactor power increase and water flow in the rector core, with
a methodology of empirical analysis. The result is compared with the nuclear re-
actor theory.
T a b l e 1 . Descriptive Statistics of Parameters (taken from Fig. 3 of [1])
Parameters Fuel
temperature, K
MCP flow
rate, m3/sec
Power (%
nominal power)
Reactivity,
%
Void,
%
Mean 210,421 9,653 67442,4 0,533 31,819
Median 131,396 9,575 13220 0,554 34,500
Maximum 570,633 10,200 227186,7 1,000 40,050
Minimum 90,100 9,3 0 0,214 12,000
Std. Dev. 147,216 0,269 90122,460 0,250 9,202
Skewness 1,371 0,713 0,872 0,228 –0,947
Kurtosis 3,722 2,396 2,039 1,972 2,837
Observations 16 16 16 16 16
Note: Max.: maximum value. Min.: minimum value. Std. Dev.: standard deviation. Skew-
ness: the measure of the probability distribution leaning to one side of the mean. Kurtosis:
“peakedness” of probability distributions. Observation: number of observations.
Yoshio Matsuki, Petro I. Bidyuk
ISSN 1681–6048 System Research & Information Technologies, 2016, № 3 34
This research focuses on the time period of 5 seconds before the explosion
(between 01h 23 min 38 sec and 01 h 23 min 42,71 sec on 25 April 1986) with the
parameters (the data) of power, MCP flow rate1, void, reactivity and fuel tempera-
ture, which are taken from Martines, et.al 1989 [1]. Table 1–2 shows the descrip-
tive statistics of the selected variables for this research.
T a b l e 2 . Descriptive Statistics of Parameters (taken from Table ii of [1])
Parameters Fuel tem-
perature, K
Fuel
energy, %
Total
energy, MJ
Total
power,MW
Water
energy, %
Water
power, %
Mean 822,0312 60,0725 24623,62 89767,5 40,075 29,51
Median 604,95 69,55 5495 9600 30,73 14,08
Maximum 1524,9 94 89200 306000 100 100
Minimum 537,9 0 0 200 8,4 5,71
Std. Dev. 359,784 33,499 32259,010 120344,200 33,389 31,315
Skewness 0,960 –0,624 0,993 0,877 0,606 1,257
Kurtosis 2,268 1,924 2,353 2,040 1,899 3,182
Obs. 16 16 16 16 16 16
Note: Max.: maximum value. Min.: minimum value. Std. Dev.: standard deviation. Skew-
ness: the measure of the probability distribution leaning to one side of the mean. Kurtosis:
«peakedness» of probability distributions. Obs.: number of observations.
METHODOLOGY
For the analysis, at first, the correlations are calculated; and coefficients of linear
models are calculated for the investigation of the strength of the relations between
the selected variables.
Estimating the coefficients of a linear model
At first, the average value )(xE of each independent variable x is calculated:
n
i
ixnxE
1
/1)( ,
where ni ,...,2,1 ; where n is the total number of the sample of the variable ix .
Then, the variance )(xV and covariance ),( yxC of the variables x and
y are calculated:
222 )()()( xxExExV , xyyxEyxC )(),( ** ,
where )(* xExx , )(* yEyy ; where y is also an independent variable.
Then, a linear regression model is constructed as follows.
Case of 1 independent variable
In case of 1 independent variable, the regression model is written as fol-
lows:
221 XccY , (1)
1 MCP flow rate: the flow rate of the Main Circulation Pump
Empirical Analysis of Chernobyl Nuclear Reactor Core for 5 Seconds before the Explosion
Системні дослідження та інформаційні технології, 2016, № 3 35
where Y is a dependent variable; 2X is an independent variable; 1c and 2c are
constant values.
The values of those coefficients are obtained by the following equations,
which are obtained by an optimization of )( 221 XccYU :
)()( 221 XEcYEc , (2)
22
2
2
X
YXc
. (3)
Case of 2 independent variables
In case of 2 independent variables, the regression model is written as fol-
lows:
33221 XcXccY , (4)
where Y is a dependent variable; jX are independent variables; 1c and jc are
constant values; where, .3,2j
The values of those coefficients are obtained by the following equations,
which are obtained by an optimization of )( 33221 XcXccYU :
)()()( 33221 XEcXEcYEc , (5)
))()1(1(
32232223232
2
2 XXYXXXXYXXXXXc , (6)
))()1(1(
32232333232
2
3 XXYXXXXYXXXXXc . (7)
Correlation coefficients
For the regression model, the independent variables iX are independent from each
other. Therefore, before formulating the model equation (1) and/or (4), the corre-
lation )( between each pair of the variables need to be investigated by the fol-
lowing equation:
ji
ji
XX
XX
ji
ji
XVXV
XXC
)()(
)(
, (8)
where ji .
Fitting (predictability) of the linear model in the data
After obtaining the correlations and the coefficients, 2c and 3c , the fitting of
the model equation (1) and/or (4) on the given data of ix and Y needs to be in-
vestigated by the following procedure:
1. Calculate the predicted value of Y (i.e., Ŷ ) with the following equation:
j
k
j
ji xccY
2
1
ˆ , (9)
where kj ....,3,2 ; i corresponds to i -th observation of the variable jx ( 2k
in equation (4); 3k in equation (4)).
Yoshio Matsuki, Petro I. Bidyuk
ISSN 1681–6048 System Research & Information Technologies, 2016, № 3 36
2. Calculate the value of R2 by the following equation:
n
i
i
i
n
i
YY
YY
R
1
2
2
12
)(
)ˆ(
, (10)
where
n
i
ixnY
1
/1 ; where ni ,...,2,1 ; n is the number of the samples of the
variable, ix .
The value of 2R represents the fitting and predictability of the given linear
model upon the given data, and when ,0,12 R it is the perfect match, while the
level of the matching is lower when the value of 2R is lower. In practice, if
6,0~8,02 R , the fitting of the model in the data is significant. However, the
threshold value depends on the topic and the data of the concerned research question,
therefore the values of 2R need to be considered on the comparative manner.
It is noted that the coefficients of the linear model ( ic , where 3,2i ), 2R
of each linear model, and the correlation )( of each pair of the variables are all
different, as each of them is calculated by different equation from each other as
shown above.
RESULTS
Formation of the linear models after calculating the correlations of the
variables
Tables 3, 4 show the correlations between each pair of the variables, which are
calculated by the equation (8).
T a b l e 3 . Correlation matrix 1
Variable FUEL
ENERGY*
FUEL
TEMPERATURE*
FUEL
TEMP2
MCP FLOW
RATE
POWER REACTIVITY
FUEL ENERGY* 1
FUEL
TEMPERATURE* 0,7202 1
FUEL TEMP2 0,6981 0,9607 1
MCP FLOW RATE –0,9861 –0,7417 –0,7310 1
POWER 0,7178 0,9883 0,9354 –0,7383 1
REACTIVITY 0,8661 0,4322 0,3850 –0,7859 0,4300 1
TOTALENERGY* 0,7182 0,9997 0,9643 –0,7428 0,9874 0,4230
TOTALPOWER* 0,7233 0,9976 0,9450 –0,7392 0,9883 0,4523
VOID 0,9736 0,6810 0,6640 –0,9729 0,6810 0,8330
WATERENERGY* –0,9996 –0,7201 –0,6937 0,9834 –0,7187 –0,8716
WATERPOWER* –0,9570 –0,5393 –0,5342 0,9589 –0,5419 –0,8245
Empirical Analysis of Chernobyl Nuclear Reactor Core for 5 Seconds before the Explosion
Системні дослідження та інформаційні технології, 2016, № 3 37
T a b l e 4 . Correlation matrix 1
Variable TOTAL
ENERGY*
TOTAL POWER* VOID
WATER
ENERGY*
WATER-
POWER*
TOTALENERGY* 1
TOTALPOWER* 0,9962 1
VOID 0,6801 0,6859 1
WATERENERGY* –0,7176 –0,7244 –0,9757 1
WATERPOWER* –0,5396 –0,5412 –0,9647 0,9556 1
Note: Number of observations is 16 as shown in Table 1 and Table 2.
FUEL ENERGY*: Fuel energy (%) in Table 2. FUEL TEMPERATURE*: Fuel tempera-
ture (K) in Table 2. FUEL TEMP2: Fuel temperature (K) in Table 1. MCP FLOW RATE:
MPC flow rate (m3/sec) in Table 1.
POWER: Power (% nominal power) in Table 1. REACTIVITY: Reactivity (%) in Table
1. TOTAL ENERGY*: Total energy (MJ) in Table 2. TOTAL POWER*: Total power
(MW) in Table 2. VOID: Void (%) in Table 1.WATER ENERGY*: Water energy (%) in
Table 2. WATER POWER*: Water power (%) in Table 2.
For the formulation of the linear model as shown in equations (1) and (4),
the dependent variable, Y, needs to be defined. In this analysis, it is assumed that
the reactor’s power indicates the transient process, inside of the nuclear reactor.
Therefore, one of the following three variables: the Power (% nominal power) in
Table 1, the Total energy (MJ) in Table 2, and the Total power (MW) in Table 2,
should be selected as the dependent variable, Y. For this selection, the correlation
between each pair of these 3 variables was examined, and the result is shown in
Table 5. As the result, it was found that each pair of these 3 variables has large
correlations, which are between 0,98 and 1,00. Upon this observation, it is con-
cluded that these 3 variables are considered to be the same indicator of the reactor
power. Therefore, it was assumed that any of these 3 variables could represent the
reactor’s power. For this research paper, the Power (% nominal power) in Table 1
is used as the dependent variable, because this value is taken from the same graph
in [1] with values of the void and reactivity, which are related to the reactor tran-
sient process of Chernobyl accident2.
T a b l e 5 . Correlations between the pairs of the candidates for dependent
variables
Case Selected pair of variables Value of
correlation
1
Power (% nominal power)
in Table 1–1
Total energy (MJ)
in Table 1–2
0,9874
2
Power (% nominal power)
in Table 1–1
Total power (MW)
in Table 1–2
0,9883
3
Total energy (MJ)
in Table 1–2
Total power (MW)
in Table 1–2
0,9962
And then, the independent variables ( iX , where 3,2i ) in the equations (1)
and (4) also need to be defined. For this purpose, it is necessary to examine the
2 The theory of the rector transient will be explained in latter part of this paper, in the sec-
tion 3.3.
Yoshio Matsuki, Petro I. Bidyuk
ISSN 1681–6048 System Research & Information Technologies, 2016, № 3 38
correlations between each pair of those variables. And, then, the variables, which
are less correlated, should be selected as independent variables. As the result, the
pairs of the variables with greater correlations are shown in Table 6; and, the pairs
with less correlations are shown in Table 7. Those 7 pairs of the variables shown
in Table 6 are not considered to be independent, therefore any of those 7 pairs
cannot be put together in the same linear model for the equation (1) and (4). On
the other hand, each of those 14 pairs of the variables shown in Table 7 can be
regarded as independent variables.
Table 6. Correlations between pairs of variables, which hold stronger correla-
tions ( 70,0 )
Case Selected pair of variables
Value of
correlation
1 Fuel temperature (K) in Table 2 Fuel temperature (K) in Table 1–1 0.9607
2 MCP flow rate (m3/sec) in Table 1 Water energy (%) in Table 1–2 0,9834
3 MCP flow rate (m3/sec) in Table 1 Water power (%) in Table 1–2 0,9589
4 Reactivity (%) in Table 1 Void (%) in Table 1–1 0,8330
5 Water energy (%) in Table 2 Water power (%) in Table 1–2 0,9556
6 Fuel energy (%) in Table 2 Fuel temperature (K) in Table 1–2 0,7202
7 Fuel energy (%) in Table 2 Fuel temperature (K) in Table 1–1 0,6981
Table 7. Correlations between pairs of variables, which hold weaker correlations
(0,70)3
Case Selected pair of variables
Value of
correlation
1 Fuel temperature (K) in Table 2 MCP flow rate (m3/sec) in Table 1 –0,7417
2 Fuel temperature (K) in Table 2 Reactivity (%) in Table 1 0,4322
3 Fuel temperature (K) in Table 2 Void (%) in Table 1 0,6810
4 Fuel temperature (K) in Table 2 Water energy (%) in Table 2 –0,7201
5 Fuel temperature (K) in Table 2 Water power (%) in Table 2 –0,5393
6 Fuel temperature (K) in Table 1 MCP flow rate (m3/sec) in Table 1 –0,7310
7 Fuel temperature (K) in Table 1 Reactivity (%) in Table 1 0,3850
8 Fuel temperature (K) in Table 1 Void (%) in Table 1 0,6640
9 Fuel temperature (K) in Table 1 Water energy (%) in Table 2 –0,6937
10 Fuel temperature (K) in Table 1 Water power (%) in Table 2 –0,5342
11 MCP flow rate (m3/sec) in Table 1 Reactivity (%) in Table 1 –0,7859
12 MCP flow rate (m3/sec) in Table 1 Void (%) in Table 1 –0,9729
13 Void (%) in Table 1 Water energy (%) in Table 2 –0,9757
14 Void (%) in Table 1 Water power (%) in Table 2 –0,9647
Analysis of the reactor’s transient by the linear model
Before the formulation of the linear model, the following scenario was assumed to
describe the process of the reactor’s transient for 5 seconds before the explosion:
1. The flow rate of the Main Circulation Pump (MCP flow rate) was re-
duced4.
3 In this process of the selection, the negative correlations (with the sign of minus) were
accounted as the less correlated.
Empirical Analysis of Chernobyl Nuclear Reactor Core for 5 Seconds before the Explosion
Системні дослідження та інформаційні технології, 2016, № 3 39
2. The voids were produced in the water inside of the reactor.
3. The increased void led to the increase of the neutron flux.
4. The power increased, leading to the explosion.
And, then, the following models were formulated, which should examine the
relations between the related variables:
,REACTIVITYeMCPFlowRatPOWER 321 ccc (11)
VOIDeMCPFlowRatPOWER 321 ccc , (12)
VOIDREACTIVITY 21 cc . (13)
At first, the influence of 2 variables (MCP Flow Rate, and REACTIVITY) to
POWER was examined by the equation (11); and, the influence of MCP Flow
Rate and REACTIVITY to POWER was examined by the equation (12).
REACTIVYT and VOID are strongly correlated (the correlation value is 0,8330
as shown in Table 6), therefore these two variables could not be put in the same
linear model. Then, the equations (11) and (12) were formulated as separate equa-
tions. In addition, the relation between VOID and REACTIVITY was examined
by the linear model, equation (13).
The other independent variables (FUEL TEMPERATURE, FUEL TEMP2)
are strongly correlated with POWER (the correlations are: 0,9883 by
FEULTEMPERATURE, and 0,9354 by FUELTEMP2 as shown in Table 3);
therefore, it was assumed these two variables were surrogate of the POWER, not
the independent variables. On the other hand, WATER ENRGY and WATER
POWER are strongly correlated with MCP Flow Rate (the correlations are:
0,9834 by WATER ENERGY, and 0,9589 by WATER POWER as shown in
Table 6); therefore, it was assumed these two variables were surrogates for MCP
Flow Rate, and not independent variables. Also, FUEL ENERGY was omitted
from this analysis, because Table 6 suggests that it has correlations with FUEL
TEMPERATURE, FUEL TEMP2, and POWER, although the values of the corre-
lations are about 0,705.
And, then the coefficients ( ic , where 3,2,1i ) of each linear model shown
in the equations (11), (12) and (13) were calculated, with the equations (2) and (3)
for the cases of 1 independent variable, and the equations (5), (6) and (7) for 2
independent variables. The calculated results are shown in Table 8, together with
calculated values of 2R .
T a b l e 8 . Calculated Linear Models
Model
Equation
Linear models and calculated coefficients 2R
14
eMCPFlowRat351394.8-3535019POWER
REACTIVITY141558,0 0,6042
15
eMCPFlowRat475560,64875626POWER
VOID6836,794 0,5712
16 VOID02266,01876,0REACTIVITY 0,6938
4 This action was taken for testing the plant’s ability of recovering the loss of external
electricity supply for the Main Circulation Pump.
5 In practice, the value of 0,70 is considered as sufficiently a high correlation.
Yoshio Matsuki, Petro I. Bidyuk
ISSN 1681–6048 System Research & Information Technologies, 2016, № 3 40
The 2R of the model equation (11) is 0,6042, while its value of the equation
(12) is 0,5712. The value of 2R shows how the predicted values by the model
equation fit in the sampled data. These calculated two values show that the pre-
dictability of the models is satisfactory by both models6; in other words, the mod-
els sufficiently fit in the data.
In both two models, the coefficients of MCP Flow Rate show similar values
in their order of magnitude. But the sign of the coefficients are both negative.
This sign is consistent with the scenario that led to the increase of the reactor
power.
On the other hand, signs of the coefficients of REACTIIVTY and VOID are
also both negative; but, the values of the coefficients are smaller than the value of
the coefficient of MCP Flow Rate. This observation suggests that the increase of
power was dominated by the reduction of the MCP Flow Rate, while
REACTIVITY and VOID were no longer influential to the increase of the reactor
power in this period of 5 seconds before the explosion.
Reactor theory
It is known that the positive void coefficient was one of the causes of the sudden
increase of the reactor power, in case of the explosion of Chernobyl reactor.
However, in the above observation during the period of a few seconds before the
explosion, the void coefficient didn’t act as the dominant factor, although the re-
activity should have increased the neutron flux on theory. Therefore, in this ob-
servation, the reactivity and/or void coefficient needs to be considered as pre-
dominant factor, of which influence was not observed dynamically during the
period of these 5 seconds. Therefore, here it is necessary to discuss this problem
with the reactor theory.
SUMMARY, CONCLUSION AND RECOOMENDATION
Empirical method was used for analyzing the transient of the nuclear reactor core,
a few second before the explosion at the time of the Chernobyl accident (between
01h 23min 38sec and 01h 23min 42,71sec). 11 parameters were taken from the
literature [1] and correlations of each pair of those variables were calculated. And,
then, 4 parameters were selected for further analyzing the process of transient be-
fore the explosion. A scenario was assumed for this analysis, such as the reduc-
tion of the flow rate of the Main Circulation Pump and the insertion of the void
caused the increase of the power for the explosion. 2 separate linear models were
made to examine this scenario. The result indicated that the reduction of the flow
rate of the Main Circulation Pump was dominant over the void and the reactivity
during the last few seconds to the explosion. And, then, the relation between the
void and the reactivity was investigated also with this methodology, and the result
was compared with the nuclear reactor theory shown in the literature [2]. The re-
sult of this comparison suggested that the value of the void coefficient was 30
pcm/%. In the literature [1], the inserted void was about 50 % before this final
moment. Therefore, the reactivity was calculated as 0,015 in the literature [2],
while the empirical analysis indicated its value as 0,023.
6 2R is about 0.60. It means that more then half of the actual data are predicted by the model.
Empirical Analysis of Chernobyl Nuclear Reactor Core for 5 Seconds before the Explosion
Системні дослідження та інформаційні технології, 2016, № 3 41
The empirical method calculates the degree of changes within each valuable,
not the absolute value such as average; and then, this methodology further calcu-
lates and determines the relation with other variable(s). Focus is made on the
changes (distribution) of the variables. In other words, empirical method empha-
sizes relations between the relative changes in the variables, while statistics exam-
ines the appropriateness of the estimated absolute values.
The result of the empirical analysis in this study shows a brief outlook of the
process of the reactor explosion of Chernobyl. The calculated reactivity by the
empirical method is not exactly as same as the value calculated by the reactor
theory, but in the same order of magnitude. Rather, the empirical method calcu-
lates the strength of the relations between different types of the variables. In this
study, one linear model was constructed to examine the influence to the sudden
power increase by the water flow in the reactor core and by the reactivity. And,
the calculated coefficients of the linear model show a significant influence of the
reduction of the circulation of reactor coolant.
The predominance of reactor design, such as indicated by the void coeffi-
cient, is well known for explaining the accident of Chernobyl: although, it is not
the aim of this paper to introduce a large number of published literatures about the
reactor design. On the other hand, the empirical analysis in this study shows how
the insertion of void and the reduction of water flow were related to the power
increase.
The literature [2] calculated the value of reactivity
eff
eff
K
K
at the time of
the reactor transient of the Chernobyl accident, as 0,015, by the following equa-
tion, given 30 pcm/% of the void coefficient and 50 % void insertion by Xenon
poisoning:
eff
eff
K
K
=Void Coefficient (pcm/%) Void Insertion (%).
On the other hand, Table 6 shows the relation between REACTIVITY and
VOID in the model (13), and the coefficient of VOID for REACTIVITY is 0,023.
This value is roughly on the same order of magnitude as the theory [2] indicates
as 0,015. Therefore, this observation shown in Table 6 also suggests that the void
coefficient is about 30 pcm/%, which was as discussed by [2].
The result of this study shows possibility of using empirical method for
analysis of physical phenomena, specifically the process of transient in the nu-
clear reactor core.
REFERENCES
1. Martinez J. M. An Analysis of the Physical Causes of the Chernobyl Accident /Jose
M. Aragonez, Emilio Mingues, Jose M. Peri, Guillermo Velarde // Nuclear Tech-
nology. — 1990. — Vol. 90. — P. 371–399.
2. Reich F. Neutron Kinetics of the Chernobyl Accident / F. Reich // ENS News. —
2005. — Issue 13.
Received 04.02.2016
From the Editorial Board: the article corresponds completely to submitted manuscript.
|
| id | nasplib_isofts_kiev_ua-123456789-140241 |
| institution | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| issn | 1681–6048 |
| language | English |
| last_indexed | 2025-12-07T18:18:31Z |
| publishDate | 2016 |
| publisher | Навчально-науковий комплекс "Інститут прикладного системного аналізу" НТУУ "КПІ" МОН та НАН України |
| record_format | dspace |
| spelling | Matsuki, Y. Bidyuk, P.I. 2018-06-26T13:29:55Z 2018-06-26T13:29:55Z 2016 Empirical analysis of Chernobyl nuclear reactor core for 5 seconds before the explosion / Y. Matsuki, P.I. Bidyuk // Системні дослідження та інформаційні технології. — 2016. — № 3. — С. 33-41. — Бібліогр.: 2 назв. — англ. 1681–6048 DOI: 10.20535/SRIT.2308-8893.2016.3.03 https://nasplib.isofts.kiev.ua/handle/123456789/140241 519.004.942 This study uses the methodology of empirical analysis for analyzing the transient mode of the nuclear reactor core, a few second before the explosion at the time of the Chernobyl accident. The parameters were selected from the published articles [1]. A scenario was assumed for this analysis, such as the reduction of the flow rate of the Main Circulation Pump, and regression models were constructed to examine this scenario. The results of the models application were examined, and conclusions were made regarding the reduction of the flow rate of the Main Circulation Pump and the reactivity during the last few seconds to the explosion. У дослідженні використоно методологію емпіричного аналізу для вивчення перехідних процесів активної зони ядерного реактора за кілька секунд до вибуху під час аварії на Чорнобильській АЕС. Параметри вибрано з опублікованих робіт [1]. Сценарієм цього аналізу передбачено зниження швидкості потоку основного циркуляційного насоса та побудовано регресивні моделі для вивчення цього сценарію. Розглянуто результати застосованої моделі і зроблено висновки про зменшення витрат головного циркуляційного насоса та реактивності протягом останніх кількох секунд до вибуху. В исследовании использована методология эмпирического анализа для изучения переходных процессов активной зоны ядерного реактора за несколько секунд до взрыва во время аварии на Чернобыльской АЭС. Параметры выбраны из опубликованных работ [1]. Сценарием этого анализа предположено снижение скорости потока основного циркуляционного насоса и построены регрессионные модели для изучения этого сценария. Рассмотрены результаты примененной модели и сделаны выводы об уменьшении расходов главного циркуляционного насоса и реактивности в течение последних нескольких секунд до взрыва. en Навчально-науковий комплекс "Інститут прикладного системного аналізу" НТУУ "КПІ" МОН та НАН України Системні дослідження та інформаційні технології Проблеми прийняття рішень і управління в економічних, технічних, екологічних і соціальних системах Empirical analysis of Chernobyl nuclear reactor core for 5 seconds before the explosion Емпіричний аналіз активної зони ядерного реактора ЧАЕС за 5 секунд до вибуху Эмпирический анализ активной зоны ядерного реактора ЧАЕС за 5 секунд до взрыва Article published earlier |
| spellingShingle | Empirical analysis of Chernobyl nuclear reactor core for 5 seconds before the explosion Matsuki, Y. Bidyuk, P.I. Проблеми прийняття рішень і управління в економічних, технічних, екологічних і соціальних системах |
| title | Empirical analysis of Chernobyl nuclear reactor core for 5 seconds before the explosion |
| title_alt | Емпіричний аналіз активної зони ядерного реактора ЧАЕС за 5 секунд до вибуху Эмпирический анализ активной зоны ядерного реактора ЧАЕС за 5 секунд до взрыва |
| title_full | Empirical analysis of Chernobyl nuclear reactor core for 5 seconds before the explosion |
| title_fullStr | Empirical analysis of Chernobyl nuclear reactor core for 5 seconds before the explosion |
| title_full_unstemmed | Empirical analysis of Chernobyl nuclear reactor core for 5 seconds before the explosion |
| title_short | Empirical analysis of Chernobyl nuclear reactor core for 5 seconds before the explosion |
| title_sort | empirical analysis of chernobyl nuclear reactor core for 5 seconds before the explosion |
| topic | Проблеми прийняття рішень і управління в економічних, технічних, екологічних і соціальних системах |
| topic_facet | Проблеми прийняття рішень і управління в економічних, технічних, екологічних і соціальних системах |
| url | https://nasplib.isofts.kiev.ua/handle/123456789/140241 |
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