AnsaldoEnergia

Divisione Nucleare
Progetto
Project
PDS-XADS
AnsaldoEnergia
Identificativo
Document no.
XADS 20 TRIX 009
Rev.
Rev.
1
Cl. ris.
class
Pagina
Page
47
Event [2.2] refers to anomalies in the Target Unit Coolant System pressure and temperature
variation originate from malfunctions or failures of systems and components normally
devoted to (directly or indirectly) control the TUCS pressure or temperature.
3.5.1 Reactor Coolant System Challenges
The phenomenologies that could result in the occurrence of event [2.1] (see Fig 3.3-1) are
listed in the level 3 MLD of the Fig. 3.5.1-1.
In the following subsections 3.5.1.1 through 3.5.1.6 a MLD will be developed for each of the
level 3 phenomenologies identified in Figure 3.5.1-1.
Figure 3.5.1-1
MLD development starting from
" RCS PRESSURE and TEMPERATURE VARIATION "
[2.1]
RCS PRESSURE or
TEMPERATURE
VARIATION
level 2
[2.1.1]
INCREASE in
HEAT
REMOVAL
from RCS
[2.1.2]
DECREASE in
HEAT
REMOVAL
from RCS
[2.1.3]
DECREASE in
PRIMARY
COOLANT
FLOWRATE
[2.1.4]
INCREASE in
PRIMARY
COOLANT
FLOWRATE
[2.1.5]
DECREASE of
PRIMARY
Pb-Bi
INVENTORY
[2.1.6]
INCREASE of
RCS
PRESSURE
level 3
3.5.1.1 Increase in Heat Removal from Reactor Coolant System
There are a number of events that could result in an increase of heat removal from the
reactor coolant system (condition 2.1.1 of Figure 3.5.1-1). They are identified through the
master logic diagram (MLD) developed for this condition, which is reported in the following
Fig. 3.5.1-2.
DNU 020/1