Deterministic Analysis of Natural Circulation Events at the Ignalina NPP

Table 1

Parameters which may impact the uncertainty of calculation results in case of all MCPs trip.

No.

Parameter

Value of the

Explanation

Width of parameter distribution

parameter in

Mean deviation

Probability

Min.

Max.

the basic case

and error[%]

distribution

calculation

Initial conditions

Par. 1

Pressure in

6.35⋅10^6

7.035·10^6

6.70·10^6

1.675·10^5[5%]

Normal

Measurement

DS, Pa

error

Par. 2

Coolant flow rate

7938

8262

8100

81 [2%]

Normal

through single

Measurement

MCP, m^3/h

error

Par. 3

Feed water

458.52

467.78

463.15

2.32 [1%]

Normal

Measurement

temperature, 𝐾

error

Par. 4

Coefficients

0.98

1.02

1.0

0.01 [2%]

Normal

which define

Measurement

steam flow rate to

error

the in-house

needs header

Par. 5

Reactor thermal

4.510·10^9

4.790·10^9

4.650·10^9

7.0·10^7[3%]

Normal

Measurement

power, W

error

Modelling parameters in the core

Par. 6

Water packing

0 (on)

1 (off)

1 (off)

—

Nonparametric

Model

assumption

Par. 7

Stratification

0 (on)

1 (off)

0 (on)

—

Nonparametric

Model

assumption

Par. 8

PV term

0 (off)

1

0 (off)

—

Nonparametric

Model

assumption

Par. 9

CCFL

0 (off)

1 (on)

0 (off)

—

Nonparametric

Model

assumption

Par. 10

Thermal front

0 (off)

1 (on)

0 (off)

—

Nonparametric

Model

tracking

assumption

Par. 11

Mixture level

0 (off)

1 (on)

1 (on)

—

Nonparametric

Model

tracking

assumption

Par. 12

Nonhomogeneous

0 (nonhomogeneous

1 (homogeneous

0 (nonhomogeneous

—

Nonparametric

Model

model)

model)

model)

assumption

Flow energy loss

Par. 13

Coefficients

0.9

1.1

1.0

0.05 [10%]

Normal

Model

which define ICV

position

assumption