Valentin Mitin, Yurij Semchenkov, Andrey Kalinushkin

International Nuclear ForumVARNA 2008

AbstractAbstract

The present report covers object, conception, The present report covers object, conception, engineering solution of construction of modern engineering solution of construction of modern system of high-powered reactor in-core control, system of high-powered reactor in-core control, including VVER-1000 (V-320) reactors.including VVER-1000 (V-320) reactors.It is known that ICMS main task is on-line It is known that ICMS main task is on-line monitoring distribution of power release field and monitoring distribution of power release field and its functioning independently of design programs its functioning independently of design programs to avoid common reason error.to avoid common reason error.It is shown in what way field of power release It is shown in what way field of power release recovery has been carrying on; rest on the recovery has been carrying on; rest on the signals of in-core neutron and temperature signals of in-core neutron and temperature sensors.sensors.

On the base of the obtained and refined information On the base of the obtained and refined information there have being automatically generated signals of there have being automatically generated signals of preventive and emergency protection on local preventive and emergency protection on local parameters (linear power to the maximum intensive fuel parameters (linear power to the maximum intensive fuel elements, reserve to heat exchange crisis, «picking elements, reserve to heat exchange crisis, «picking factor»).factor»).There have represented technology on sensors and There have represented technology on sensors and processing methods of SPND and TC signals, ICIS processing methods of SPND and TC signals, ICIS composition and structure, program hard ware, system composition and structure, program hard ware, system and applied software. Structure, composition and the and applied software. Structure, composition and the taken decisions allow combining class 1E and class B taken decisions allow combining class 1E and class B and C tasks in accordance with international norms of and C tasks in accordance with international norms of separation and safety classes’ realization.separation and safety classes’ realization.At present ICIS-M is a system, providing implementation At present ICIS-M is a system, providing implementation of control, safety, information and diagnostic functions, of control, safety, information and diagnostic functions, which allow securing actual increase of quality, reliability which allow securing actual increase of quality, reliability and safety in operation of nuclear fuel and NPP units. and safety in operation of nuclear fuel and NPP units. And at the same time it reduces human factor negative And at the same time it reduces human factor negative influence to core work thermo technical reliability in the influence to core work thermo technical reliability in the operational process.operational process.

GoalsGoals

The goal of creation of In-core Instrumentation system The goal of creation of In-core Instrumentation system (ICIS) for high-powered reactors, including VVER-1000 (ICIS) for high-powered reactors, including VVER-1000

reactors, is increasing of NPP operation safety and reactors, is increasing of NPP operation safety and efficiency, due to:efficiency, due to:

Increasing of response speed, precision, reliability of Increasing of response speed, precision, reliability of operational monitoring of neutron-physical and thermal operational monitoring of neutron-physical and thermal hydraulic parameters of the reactor core and primary circuit in hydraulic parameters of the reactor core and primary circuit in stationary and transitional regimes including situation when fuel stationary and transitional regimes including situation when fuel assemblies with individual characteristics are used;assemblies with individual characteristics are used;Reduction of human factor negative influence to core work Reduction of human factor negative influence to core work thermo technical reliability in the operational process;thermo technical reliability in the operational process;Information support provision during transient monitoring Information support provision during transient monitoring modes;modes;Detection of anomaly in-core function at the first stages of their Detection of anomaly in-core function at the first stages of their occurrence with the purpose of exclusion of undesirable power occurrence with the purpose of exclusion of undesirable power liberation surges, including provision of “mild” condition of liberation surges, including provision of “mild” condition of nuclear fuel operation.nuclear fuel operation.

Widely developed self-diagnostic function, Widely developed self-diagnostic function, providing monitoring and timely indication providing monitoring and timely indication during malfunction of some equipment during malfunction of some equipment elements (units), and elements (units), and Software elements, producing difficulties Software elements, producing difficulties and reduction of number of system and reduction of number of system functions, and functions, and Signalization of unauthorized access to Signalization of unauthorized access to the system.the system.

The system should possesThe system should posses

ConceptionConception

The logic of function and correspondingly, The logic of function and correspondingly, conception of modern ICIS structure and conception of modern ICIS structure and architecture construction cause two-level architecture construction cause two-level ICIS structure, every level of which is ICIS structure, every level of which is realized in the form of dubbed Soft and realized in the form of dubbed Soft and Hardware Complex of Lower Level (SHW-Hardware Complex of Lower Level (SHW-LL) and Upper Level (SHW-UL). LL) and Upper Level (SHW-UL).

On the low level (SHW-LL)On the low level (SHW-LL)On-the-fly (not more than 0.5 sec. delay) in On-the-fly (not more than 0.5 sec. delay) in seven layers on core height, using particular seven layers on core height, using particular calibration coefficients, it is determined maximal calibration coefficients, it is determined maximal linear power of fuel elements of every 163 fuel linear power of fuel elements of every 163 fuel assemblies. assemblies. This allows detecting in time exceeding of local This allows detecting in time exceeding of local parameters permissible limits in case of Control parameters permissible limits in case of Control Rods uncontrolled motion, or in case of Rods uncontrolled motion, or in case of operator’s error. Then it is made comparison operator’s error. Then it is made comparison with the set-points and it is given an automatic with the set-points and it is given an automatic protection signal in case if local parameters protection signal in case if local parameters (Fuel element linear power or DNBR) exceed (Fuel element linear power or DNBR) exceed permissible limits.permissible limits.

Following calculations are made on the upper Following calculations are made on the upper level with inaccuracy not more than level with inaccuracy not more than (2 (2 2.5 2.5

%):%):

The current distribution of power release The current distribution of power release volume field and its functionals in space volume field and its functionals in space 16316316;16;The calibration coefficients for lower level, The calibration coefficients for lower level, forecasting calculations of core dynamic forecasting calculations of core dynamic behavior for transient modes behavior for transient modes management.management.

Technical decisionsTechnical decisions

Fig. 1. General structural diagram

In the steady-state basic operation mode of a nuclear In the steady-state basic operation mode of a nuclear power plant with the VVER-1000 reactors, the total power plant with the VVER-1000 reactors, the total

thermal power thermal power NNААKZKZ released in the reactor was released in the reactor was determined by five independent methodsdetermined by five independent methods

according to the readings of ionization chamber sensors according to the readings of ionization chamber sensors being a part of the neutron flux monitoring equipment being a part of the neutron flux monitoring equipment (NFME), (NFME), NNАКАКNPNP,,according to the readings of self-powered neutron according to the readings of self-powered neutron detectors (SPND), detectors (SPND), NNSPNDSPND,,according to the readings of the sensors monitoring the according to the readings of the sensors monitoring the thermal parameters of circuit I, thermal parameters of circuit I, NNIIкк,,according to the readings of the sensors monitoring the according to the readings of the sensors monitoring the thermal parameters of circuit II, thermal parameters of circuit II, NNIIIIкк,,by the flow rate of feeding water in the circuit, by the flow rate of feeding water in the circuit, NNPVDPVD. .

SensorsSensors

To monitor core distribution of To monitor core distribution of volume field of power release, volume field of power release,

signals are usedsignals are used

448 (7448 (764) rhodium Self-Power Neutron 64) rhodium Self-Power Neutron Detector (SPND);Detector (SPND);95 thermocouples (TC) ChrAl;95 thermocouples (TC) ChrAl;16 TC (ChrAl) and 8 thermo resistors (TR) 16 TC (ChrAl) and 8 thermo resistors (TR) at primary circuit hot and cold legs at primary circuit hot and cold legs

Soft and Hardware Complex of Soft and Hardware Complex of Lower Level Lower Level

Built on the base of the equipment, meeting RF modern Built on the base of the equipment, meeting RF modern standard requirements, IEC and IAEA norms and requirements standard requirements, IEC and IAEA norms and requirements which cover safety important systems, and acquire improved which cover safety important systems, and acquire improved metrological, reliable and time characteristics. metrological, reliable and time characteristics. Seismic stable. High requirements to internal impact protection Seismic stable. High requirements to internal impact protection (disturbance proof, seismic stability, climatic influence stability) (disturbance proof, seismic stability, climatic influence stability) allow using the equipment in hard industrial conditions in allow using the equipment in hard industrial conditions in various climatic zones.various climatic zones.With doubling of data links and power supply in equipment and With doubling of data links and power supply in equipment and also connection channels.also connection channels.Meets 1E safety class requirements. Meets 1E safety class requirements. Measuring, processing and information transfer cycle into Measuring, processing and information transfer cycle into SHW-UL is 1 sec. SHW-UL is 1 sec.

16 18 20 22 24 26 28 30 32 34 36 38 40 42

01

02

0304

05

06

07

08

0910

11

121314

15

41393735333129272523211917

1 4 1

1

1

1

1

1

1

11

1

22

2

22

2

2

2

2

2 2

4

4

4

44

4 4

4

4 3

3

3

3 3

3

3

3

3

66

6 6 6

66

6

6

5 5

5

5

5

5

5

5

5

5

6

6

3 5

B

A A

B

HPA with VIK

HPA with thermal couple

Cartogram of location КNI with SPND, TC, and Control Rods

The section of the center of active zone

The section of the second row

Soft and Hardware Complex Soft and Hardware Complex of Upper Level (SHW-UL)of Upper Level (SHW-UL)

Key features of SHW-ULKey features of SHW-UL technical platform go as followstechnical platform go as follows

Software and Hardware work in operational environment “Unix” Software and Hardware work in operational environment “Unix” (SUN “Solaris”, “Linux” etc.);(SUN “Solaris”, “Linux” etc.);sample architecture of open systems, which enables creation of sample architecture of open systems, which enables creation of modern and prospective decisions on the base of widely used modern and prospective decisions on the base of widely used standards (standards – POSIX 1, 1.b, 1.c and others);standards (standards – POSIX 1, 1.b, 1.c and others);the most technological industrial constructive (reliability, repair the most technological industrial constructive (reliability, repair ability, assembling decision spectrum) – Compact PCI;ability, assembling decision spectrum) – Compact PCI;high productivity – processor modules with operating speed, high productivity – processor modules with operating speed, enough for analysis of the reactor unit state, including modeling enough for analysis of the reactor unit state, including modeling of core neutron-physical and thermo hydraulic processes in real of core neutron-physical and thermo hydraulic processes in real time;time;system reliability with application of new structural decisions, system reliability with application of new structural decisions, including some components control and monitoring, and also including some components control and monitoring, and also support of cluster technologies for full use of computing support of cluster technologies for full use of computing resources together with automatic resources reconfiguration in resources together with automatic resources reconfiguration in case of components or modules failure.case of components or modules failure.

Flux Distribution of fuel elements. The section through Flux Distribution of fuel elements. The section through the center of the core A–A. The Upper level.the center of the core A–A. The Upper level.

Flux Distribution of fuel elements. The section through Flux Distribution of fuel elements. The section through the center of the core A–A. The Middle level.the center of the core A–A. The Middle level.

Flux Distribution of fuel elements. The section through Flux Distribution of fuel elements. The section through the center of the core B–B. The Upper level.the center of the core B–B. The Upper level.

Flux Distribution of fuel elements. The section through Flux Distribution of fuel elements. The section through the center of the core B–B. The Middle level.the center of the core B–B. The Middle level.

ResultsResults

the 5th and 6th blocks at the Kozloduy the 5th and 6th blocks at the Kozloduy nuclear power plant and nuclear power plant and the newly built 3rd block of the Kalinin the newly built 3rd block of the Kalinin nuclear power plant and nuclear power plant and the 1st and 2nd blocks of the nuclear the 1st and 2nd blocks of the nuclear power plant in Chinapower plant in China

Khortitsa-M” application software package in Khortitsa-M” application software package in combination with SHW-UL were tested and combination with SHW-UL were tested and

put into operationput into operation

Determination of the Determination of the measurement errors for the total measurement errors for the total

thermal powerthermal power

The measurement error for The measurement error for the total thermal power at the total thermal power at

transient regimestransient regimes

Fig. 7. Reactor unloading, MCP disconnecting, changes in the departure from Fig. 7. Reactor unloading, MCP disconnecting, changes in the departure from nucleate boiling rationucleate boiling ratio

Fig. 8. Time delay in controlling the core heat power using dc SPND Fig. 8. Time delay in controlling the core heat power using dc SPND

The monitoring error at the The monitoring error at the steady-state basic regimesteady-state basic regime

Results of measurements and statistical weights for calculating power Results of measurements and statistical weights for calculating power NNAKZAKZ ((The 3rdThe 3rd block block ««KalininskayaKalininskaya»)»)

 Measuring values Ni

Calculated weights wi

Results on 5 measurementsNAKNP 2905,8 0,2383NDPZ 2871,3 0,2434N1K 2894,5 0,2428N2K 2870,8 0,2432NPVD 2667,9 0,0323

Results on 3 measurementsNDPZ 2871,3 0,4157N1K 2894,5 0,1728N2K 2870,8 0,4115

Results on 2 measurementsNDPZ 2871,3 0,5000N2K 2870,8 0,5000

Results of calculating powerResults of calculating power NNAKZAKZ and indices of error and indices of error of measuring of measuring ((The 3rdThe 3rd block block ««KalininskayaKalininskaya»)»)

Relative variance

Relative error of measuring with level of confidence

NAKZ σ 95% 99% 99,9%5 measurements 2877,84 106,33 3,69% 3,24% 4,26% 5,44%

3 measurements 2875,08 14,31 0,50% 0,56% 0,74% 0,95%

2 measurements 2871,05 0,35 0,01% 0,02% 0,02% 0,03%

Fig. 9. Operation model of Rhodium detector equipped Fig. 9. Operation model of Rhodium detector equipped with corrective filter and Kalman filterwith corrective filter and Kalman filter

Fig. 10. Outcomes of processing SPND currents using Kalman filter with various assigned response rates, and corrective filter with assigned

scanning rate

Fig. 11. Arrangement of ICIS detectors at Kozloduy NPP, Unit 5

KNI

Monitoring KNI

The cell with fallen cluster

Fig. 12. Position of CR 11-26 during the falling and withdrawalFig. 12. Position of CR 11-26 during the falling and withdrawal

Fig. 13. Position of CR 11-26 during the falling in the first 11 secondsFig. 13. Position of CR 11-26 during the falling in the first 11 seconds

Fig. 14. Position of CR 05-26 and other control rods of bank 10 with CR falling in channel 11-26 during 10 min

Fig. 15. SPND currents in NFMC 12-25 without elimination of delay period at the moment of CR falling in channel 11-26 (10 seconds)

Fig. 16. SPND dc in NFMC 12-25 with eliminated delay period at the moment of CR falling in channel 11-26 (with Kalman filter) (10 seconds)

16.11.2005 КНИ 12-25 Без фильтра Калмана

0.65

0.7

0.75

0.8

0.85

0.9

0.95

1

1.05

1.1

19:

34:0

1

19:

34:5

9

19:

35:5

7

19:

36:5

5

19:

37:5

3

19:

38:5

1

19:

39:4

9

19:

40:4

7

19:

41:4

5

19:

42:4

3

19:

43:4

1

19:

44:3

9

19:

45:3

7

19:

46:3

5

19:

47:3

3

19:

48:3

1

19:

49:2

9

19:

50:2

7

19:

51:2

5

19:

52:2

3

19:

53:2

1

19:

54:1

9

19:

55:1

7

19:

56:1

5

19:

57:1

3

19:

58:1

1

19:

59:0

9

20:

00:0

7

20:

01:0

5

20:

02:0

3

20:

03:0

1

20:

03:5

9

20:

04:5

7

Время, сек

Ток,

мкА КНИ 12-25-1 (мкА)

КНИ 12-25-4 (мкА)КНИ 12-25-7 (мкА)

Fig. 17. SPND currents without elimination of delay period at the moment of CR falling in channel 11-26 depicted within expanded time interval

(10 minutes)

16.11.2005 КНИ 12-25 Фильтр Калмана

0.65

0.7

0.75

0.8

0.85

0.9

0.95

1

1.05

1.1

19:

34:0

1

19:

34:5

2

19:

35:4

3

19:

36:3

4

19:

37:2

5

19:

38:1

6

19:

39:0

7

19:

39:5

8

19:

40:4

9

19:

41:4

0

19:

42:3

1

19:

43:2

2

19:

44:1

3

19:

45:0

4

19:

45:5

5

19:

46:4

6

19:

47:3

7

19:

48:2

8

19:

49:1

9

19:

50:1

0

19:

51:0

1

19:

51:5

2

19:

52:4

3

19:

53:3

4

19:

54:2

5

19:

55:1

6

19:

56:0

7

19:

56:5

8

19:

57:4

9

19:

58:4

0

19:

59:3

1

20:

00:2

2

20:

01:1

3

20:

02:0

4

20:

02:5

5

20:

03:4

6

20:

04:3

7

Время, сек

Ток,

мкА

КНИ 12-25-1 (мкА)КНИ 12-25-4 (мкА)КНИ 12-25-7 (мкА)

Fig. 18. SPND currents with eliminated delay period at the moment of CR falling in channel 11-26 depicted within expanded time interval

(10 minutes)

Calculation of errors for the Kalinin nuclear Calculation of errors for the Kalinin nuclear power plant at different values of power plant at different values of ТТeffeff

BLOCK Teff

Which cells are included in calculation

All

With Kq >1

Kq >1.2

Q <90

Kq>1 and

Q<90

Kq>1.2 and

Q<90

No detect

ors

Detectors only

1 8 5.37 4.39 3.99 5.47 4.48 4.18 5.81 5.06

20 3.88 3.32 3.10 3.94 3.36 3.17 4.51 3.41

40 3.62 3.03 3.10 3.65 3.03 3.18 4.32 3.09

3 2 2.31 2.30 2.23 2.31 2.31 2.23 2.58 2.11

10 2.29 2.28 2.26 2.29 2.29 2.26 2.46 2.17

20 2.32 2.27 2.19 2.33 2.28 2.19 2.45 2.24

The errors in the determination The errors in the determination of the linear power release in of the linear power release in

the SPND locations at the the SPND locations at the steady-state basic regimesteady-state basic regime

Problems:Problems:

the changes in the dimensions of the the changes in the dimensions of the emitter in all SPNDs;emitter in all SPNDs;the displacements of SPNDs from the the displacements of SPNDs from the expected design position;expected design position;the errors in determining the sensitivity the errors in determining the sensitivity coefficients;coefficients;the correctness in the elimination of delay the correctness in the elimination of delay in the flexible manner etc.in the flexible manner etc.

the total thermal power released in the core the total thermal power released in the core determined based on the recovered field and determined based on the recovered field and the total thermal power calculated based on the the total thermal power calculated based on the thermal and hydraulic parameters of the first and thermal and hydraulic parameters of the first and second circuits. second circuits.

The uncompensated systematical errors, The uncompensated systematical errors, which are not revealed by the statistical which are not revealed by the statistical

analysis, should manifest themselves via the analysis, should manifest themselves via the discrepancy between:discrepancy between:

All systematic and random deviations, which All systematic and random deviations, which were not eliminated, contribute to the were not eliminated, contribute to the resulting value of the statistically estimated resulting value of the statistically estimated error of the recovered power release field. error of the recovered power release field. The statistical estimate of the error is defined The statistical estimate of the error is defined in terms of the root-mean-square deviation of in terms of the root-mean-square deviation of the volumetric factor characterizing the the volumetric factor characterizing the inhomogeneity of the power release field from inhomogeneity of the power release field from its the most reliable value with respect to the its the most reliable value with respect to the nominal fuel and SPND parameters.nominal fuel and SPND parameters.

The errors in the determination The errors in the determination of volumetric factor of volumetric factor

characterizing the heterogeneity characterizing the heterogeneity of power release in the SPND-of power release in the SPND-

free prismsfree prisms

Dependencies upon time of rhodium SPND indications Dependencies upon time of rhodium SPND indications

Without delay

With delay

About conception of man-About conception of man-machine interfacemachine interface

Minimization of human factor unfavorable consequences Minimization of human factor unfavorable consequences is solved the most efficiently by reliable automatization is solved the most efficiently by reliable automatization of routine control actions to regulation controls of routine control actions to regulation controls Human factor favorable influence gain is the most Human factor favorable influence gain is the most effectively solved by provision of continuous monitor effectively solved by provision of continuous monitor screen view of the current information about core main screen view of the current information about core main processes, which are the most advisable for operations processes, which are the most advisable for operations staff attention, and giving a chance to influence the staff attention, and giving a chance to influence the above mentioned processes. Such information, above mentioned processes. Such information, presented in friendly, ergonomically self-possessed presented in friendly, ergonomically self-possessed form, attracts operations staff attention to the reactor form, attracts operations staff attention to the reactor processes and induces to be always ready to make an processes and induces to be always ready to make an optimal decision.optimal decision.Efficiently and properly presented information about the Efficiently and properly presented information about the results of previous impacts and core current status has a results of previous impacts and core current status has a mobilized effect on operations staffmobilized effect on operations staff

The graph SPND signals offsets

The graph of calculated offsets

Position of working group

Conclusions

Modern ICIS system for VVER-1000, Modern ICIS system for VVER-1000, including a number of sensors, cable runs, including a number of sensors, cable runs, corresponding measuring equipment and corresponding measuring equipment and computer engineering, software, computer engineering, software, accumulated 30 year experience of accumulated 30 year experience of intrareactor researches on VVER reactors intrareactor researches on VVER reactors and is capable to ensure carrying out of and is capable to ensure carrying out of control, protection, informational, diagnostic control, protection, informational, diagnostic functions and thus to promote real increase functions and thus to promote real increase of quality, reliability and safety in nuclear fuel of quality, reliability and safety in nuclear fuel and NPP power units operationand NPP power units operation ..