Thermal-Hydraulic System Codes in Nulcear Reactor Safety and Qualification Procedures
Table 1
Parameters and acceptable errors for the nodalization qualification at “steady-state” level.
Quantity
Acceptable error ()
1
Primary circuit volume
1%
2
Secondary circuit volume
2%
3
Nonactive structure heat transfer area (overall)
10%
4
Active structure heat transfer area (overall)
0.1%
5
Non-active structure heat transfer volume (overall)
14%
6
Active structure heat transfer volume (overall)
0.2%
7
Volume versus height curve (i.e., “local” primary and secondary circuit volume)
10%
8
Component relative elevation
0.01 m
9
Axial and radial power distribution ()
1%
10
Flow area of components like valves, pumps orifices
1%
11
Generic flow area
10%
(*)
12
Primary circuit power balance
2%
13
Secondary circuit power balance
2%
14
Absolute pressure (PRZ, SG, ACC)
0.1%
15
Fluid temperature
0.5% (**)
16
Rod surface temperature
10 K
17
Pump velocity
1%
18
Heat losses
10%
19
Local pressure drops
10% ()
20
Mass inventory in primary circuit
2% ()
21
Mass inventory in secondary circuit
5% ()
22
Flow rates (primary and secondary circuit)
2%
23
Bypass mass flow rates
10%
24
Pressurizer level (collapsed)
0.05 m
25
Secondary side or downcomer level
0.1 m ()
°The % error is defined as the ratio (reference or measured value—calculated value). The “dimensional error” is the numerator of the above expression. *With reference to each of the quantities below, following a one-hundred-second “null-transient” calculation, the solution must be stable with an inherent drift <1%/100 second. **And consistent with power error.
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Of the difference between the maximum and minimum pressure in the loop.
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And consistent with other errors.
