VGB POWERTECH 7 (2021) - International Journal for Generation and Storage of Electricity and Heat

Verification of SPACE code based on an MSGTR experiment at the ATLAS-PAFS facility VGB PowerTech 7 l 2021
Tab. 2. Sequence of transient analysis result.
Event Experiment (t = t*) SPACE code (t = t*) Remarks
MSGTR initiation 0.0000 0.0000
of the primary system was reduced by the
break, the pressure of the PZR was predicted
to be lower than the experiment results
(t* < 0.2 in F i g u r e 7 ). The pressure of
the primary system was relatively lower
than that obtained in the experiment results,
thus indicating a lower break flow
rate. Due to the lower break flow rate, the
pressure of PZR was maintained somewhat
higher than the experiment result, which
PZR heater off at same time as experiment
scenario
HSGL signal 0.0011 0.0024 SG collapsed water level > set-point
Reactor trip 0.0011 0.0024
MSIV close 0.0015 0.0028
MFIV close 0.0018 0.0031
Coincident with HSGL
Decay power start 0.0023 0.0036 Delay times after reactor trip
MSSV first opening 0.0026 0.0033 SG pressure > set-point
LPP signal 0.0248 0.0232 PZR pressure < set-point
SIP injection start 0.0276 0.0260 Delay times after LPP signal
PAFS operation start 0.7204 0.7173 SG collapsed water level < set-point
resulted in the break flow rate being maintained
(t* > 0.2 in F i g u r e 7 ). At the moment
the break occurred, the pressure in
the pressurizer began to decrease rapidly
due to the loss of coolant through the break
point. The depressurization rates of the
pressurizer obtained from the experiment
and the calculation results were almost the
same, as shown in F i g u r e 7. The pressure
in the pressurizer continually decreased
and reached the set point of the LPP signal.
As the LPP signal was generated, the SIP
injection was initiated, as shown in F i g -
u r e 8 . During the beginning phase of SIP
injection, the calculation result of the SIP
flow rate was slightly higher than the experimental
result. This was attributed to
that fact that the PZR pressure according to
the calculation result remained lower than
that obtained in the experiment result. As
the accident progressed, the SIP injection
rate obtained in the calculation result was
consistent with the experiment result.
When the RCS pressure reached the saturation
pressure due to the decay power, plateau
pressure was observed. In addition,
the water injected by the SIP contributed to
the primary system pressure. Thus, as
shown in F i g u r e 7, the primary system
pressure was maintained.
3.2.3 Secondary system behaviors
After the MSIVs were closed by the HSGL
signal, the pressure in the steam generator
was maintained within the range of the
opening and closing set points of the MSS-
Vs. The transient behavior of pressure in
the steam generator shows that the calcu-
1.2
0.40
Non-dimensional Core power (-)
1.0
0.8
0.6
0.4
0.2
Core power
Exp.
SPACE code
Non-dimensional Mass flow rate (-)
0.35
0.30
0.25
0.20
0.15
0.10
0.05
Break flow rate
Exp.
SPACE code
0.0
0.0 0.2 0.4 0.6 0.8 1.0
Non-dimensional Time (-)
Fig. 5. Comparison result of core power.
0.00
0.0 0.2 0.4 0.6 0.8 1.0
Non-dimensional Time (-)
Fig. 6. Comparison result of MSGTR break flow rate.
Non-dimensional Pressure (-)
1.2
1.0
0.8
0.6
0.4
0.2
System pressure
Exp. (PZR)
Exp. (SG-1)
Exp. (SG-2)
SPACE code (PZR)
SPACE code (SG-1)
SPACE code (SG-2)
Non-dimensional Mass flow rate (-)
0.10
0.08
0.06
0.04
0.02
SIP injection rate
Exp. (SI P-1)
Exp. (SIP-3)
SPACE code (SIP-1)
SPACE code (SIP-3)
0.0
0.0 0.2 0.4 0.6 0.8 1.0
Non-dimensional Time (-)
Fig. 7. Comparison result of system pressure.
0.00
0.0 0.2 0.4 0.6 0.8 1.0
Non-dimensional Time (-)
Fig. 8. Comparison result of SIP injection rate.
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