Emerson Sempell PSRV VS99 User manual

SEMPELL MODEL PSRV - PRESSURIZER SAFETY RELIEF VALVES
TYPE VS99 PILOT OPERATED
The design, construction and activation of the safety valves depends on the
design of the respective reactor and the corresponding specifications
FEATURES
• Extremely high sealing force, ensuring leak
tightness up to the set pressure.
• Very precise reproducibility of set pressure
and small operating pressure differences,
accuracy of pilot set pressure opening value
with repeats better 1%.
• All parts essential for function are kept at
operating temperature, thus no thermal shock.
• The disc piston is the only moving part in the
main valve, providing reduced maintenance.
• Low or high pressure in-situ test during
operation to preventive maintenance.
• Compact design from forged stainless steel.
• Redundancy of pilot valves and diversity of
function principle of pilot valves according to
specification.
• Suitable for all types of nuclear reactors.
TECHNICAL DATA
Size: Up to DN 200
Temperature: Up to 371°C
Pressure: Up to 200 bar
According to customer requirements and
specifications.
GENERAL APPLICATION
Pressurizer safety relief valves protect the
pressurizer from overpressure and must
ensure the following functions:
• Pressurizer relief for normal operating
transients
• Hot and cold overpressure protection on
liquid, steam, gas and steamwater-mixture
• Depressurization of reactor coolant system
following an accident
VCTDS-03163-EN 17/05
Emerson.com/FinalControl © 2017 Emerson. All rights reserved.

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SEMPELL MODEL PSRV - PRESSURIZER SAFETY RELIEF VALVES
TYPE VS99 PILOT OPERATED
Pressurizer safety relief valves
Containment building
Blowdown
tank
Pressurizer
Steam
generator
Turbine
Generator
Air and water vapor
Condenser
Water
Preheater
Emergency cooling system
Reactor
sump
Reactor pressure vessel
Cooling
tower

3
SEMPELL MODEL PSRV - PRESSURIZER SAFETY RELIEF VALVES
TYPE VS99 PILOT OPERATED
INTRODUCTION
Pilot operated safety relief valves are used to protect the pressurizer against overpressure. In
pressurized water reactors, the energy of the primary circuit is transferred to the secondary
steam system by the steam generators. The pressurizer compensates for any expansion in the
coolant volume occurring during operation and accidents. The design criterion for pressurizer
safety valves is not the reactor power but the maximum possible volume expansion of the coolant
in response to a temperature increase.
The valves' design takes into account the combination of failures which will produce the maximum
possible pressure and temperature rise, leading to the maximum blowoff rates required. The
VS99 is a pilot operated safety relief valve which operates to the relief principle. The operating
pressure is applied to the valve disc. When the pressure increases, the sealing force on the valve
seat rises.
HISTORY
1970 First delivery of pilot-operated safety
valves to NPP Stade in Germany
based on a conventional technology.
1980 Qualification under hot water
conditions.
1985 ATWS qualification.
1990 First supply of PDE valves with Sieka
actuator.
1992 First installation of degasification.
2003 ASME III qualification
2011 First delivery of pilot-operated safety
valves with ASME NV stamp.
The safety valve will follow the commands of the pilot valves: If the pilot valves open, the safety
valve opens; if the pilot valves close, the safety valve closes.
Several pilot valves are assigned to each safety valve. Each pilot valve has a pressure relief line
and a pilot line. Each pilot valve can be blocked for repair purposes. The corresponding stop
valves are locked by valve locking devices according to the regulations, in such a way that each of
the pressurizer safety relief valves is always kept ready for operation by at least one functioning
pilot valve.
For the entire control system, i.e. for the main valve with the associated pilot valves, an
earthquake-proof design with a compact arrangement is recommended. With such a design,
pipelines as pilot lines are completely eliminated. Thus pressure chambers to be relieved are as
small as possible. The dead times during discharge and loading are therefore small.
Sempell has a large installation base of pressurizer safety relief valves in all German
Siemens/KWU reactors and in most of the Russian PWR reactors type VVER, as well as the GEN III
reactors, such as the French EPR and the Korean APR1400.
Over the years, comprehensive qualification programs for the different reactor types have been
carried out. Sempell has the requisite quality assurance systems and is qualified in accordance
with KTA and ASME III.
Based on this experience and the technological development, Sempell offers special solutions
for the new GEN III reactors. The valves for the European EPR are delivered in accordance with
RCC-M, the valves for the Russian PWR (type VVER) in accordance with NP-068-05 and the valves
for the Korean APR1400 in accordance with ASME III (NV stamp).

4
SEMPELL MODEL PSRV - PRESSURIZER SAFETY RELIEF VALVES
TYPE VS99 PILOT OPERATED

5
VTS1
VS99
DN 250
VTS1
VS99
DN 200
ETS1
DN 25
DN 50
DN 80
VS66
DN 25
VCA
DN 15
VS99
DN 125
DN 250
DN 125
DN 125
DN 125
DN 25
DN 15
DN 25
DN 25
DN 50
DN 25
DN 25
ETS1
DN 25
DN 50
DN 80
DN 25
DN 50
DN 25 DN 25
DN 15
DN 25
VTS1
ESS1
SEMPELL MODEL PSRV - PRESSURIZER SAFETY RELIEF VALVES
TYPE VS99 PILOT OPERATED
THE GERMAN KWU-PWR SOLUTION
2 VS99 safety valve
2 x 4
VS66 self-acting spring-loaded pilot valve
with stop valve for thepilot line
2 x 2 ETS (doubled) stop valve
2 x 1 PDE (doubled) bleed and feed valve
2 x 1 VTS1 stop valve for pressure measurement
1 VS99 blowdown valve
1 x 1 VCA solenoid valve
1 x 1 PDE (single) bleed and feed valve
1 x 1 VTS1 stop valve for pressure measurement
VALVE ASSEMBLY
At German pressurized water systems of the KWU, three main valves type VS99 are installed in
the pressurizer system: two providing double redundancy plus one operational blow-down valve.
The VS99 safety valve
For optimized availability, four self-acting spring-loaded pilot valves type VS66 were mounted
redundantly to each main valve: two are in service, two rest in standby. These spring-loaded pilot
valves operate autonomously; no external energy is needed to open them. Each pilot valve, as
needed, can be blocked by a stop valve.
In the case of the emergency cooling, the system pressure must be reduced. Thisis accomplished
with a pressure relief valve type PDE, which is electrically actuated and therefore can also be
opened below the set pressure of the VS66. The process of the primary circuit pressure relief to
ensure the emergency cooling supply is referred to as the "bleed and feed" process.
Pilot operated
safety relief valve
Solenoid valve
Pilot operated
safety relief valve
PDE-valve PDE-valve
Blowdown valve
Stop valve
Pressurizer relief tank Pressurizer
PDE-
valve
Spring
loaded
pilot
valves
The VS99 blowdown valve
In addition to the pressurizer safety relief valves, a blowdown valve is arranged on the dome of
the relief tank and connected with the steam chamber of the pressurizer by a blowdown line.
A stop valve is installed upstream of the blowdown valve. The construction of the blowdown
valve corresponds to the construction of the pressurizer safety relief valve; nonetheless on the
pressurizer blowdown valve, a solenoid valve is installed as pilot valve. In normal operation, the
blowdown valve and the pilot valve are closed. When required, the pilot line is opened by the
solenoid valve and opens the blowdown valve. The blowdown valve can also be actuated by the
motor-driven bleed and feed valve.

6
SEMPELL MODEL PSRV - PRESSURIZER SAFETY RELIEF VALVES
TYPE VS99 PILOT OPERATED

7
DN 80
DN 80
DN 80
DN 80
DN 80
DN 80
DN 150
DN 150
DN 150
DN 150
DN 150
DN 150
DN 150
DN 150
VS99
VS99 VS99 VS99
VS66
VS66 VS66 VS66
PDE
PDEPDEPDE
SEMPELL MODEL PSRV - PRESSURIZER SAFETY RELIEF VALVES
TYPE VS99 PILOT OPERATED
VALVE ASSEMBLY
At the type APR 1400 reactors, four pressurizer safety relief valves type VS99 are mounted in a
horizontal position directly on the pressurizer, to ensure a compact arrangement and optimized
pipe conduction. Two proven self-acting spring-loaded pilot valves type VS66 per main valve
are used for redundancy, whereby the impulse and pilot lines can be isolated by integrated stop
valves.
The steam pilot valves are connected to system pressure by independent feeding lines within the
main valve inlet flange. No external lines are foreseen producing this compact design.
4 VS99 safety valve
4 x 2 VS66 self-acting spring-loaded pilot valve
with stop valve for the pilot line
4 x 1 PDE (doubled) bleed and feed valve
A double motor pilot valve type PDE serves as the so-called bleed and feed valve, to open the main
valve under the set pressure of the VS66 pilot valve.
Comprehensive tests and qualifications for the horizontal position of the main valve have been
successfully concluded. In December 2011, attended by the ANI (Authorized Nuclear Inspector),
the design was granted the NV stamp. The valve station is qualified for steam, two-phase flow
(water-steam) and supercooled water.
THE KOREAN APR1400 SOLUTION
Springloded
pilot valve
Pressurizer
Safety relief
valve
Pilot
valve
Pressurizer relief tank

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SEMPELL MODEL PSRV - PRESSURIZER SAFETY RELIEF VALVES
TYPE VS99 PILOT OPERATED

9
VS99
DN50
DN25
DN15
DN200
DN150
VS99VS99
DN400
DN200
DN200
DN150
DN150
DN150
DN25
DN 51
DN25
DN25
DN25
DN25
DN 51
DN25
DN150
DN25 DN25 DN25
DN15
DN15
DN15
DN15
DN15
DN25 DN25
DN25
DN25 DN25 DN25 DN25
DN25
DN25
DN50 DN50
DMSDMSDMS
DN 51
DN 51
DN 51
DN 51
SEMPELL MODEL PSRV - PRESSURIZER SAFETY RELIEF VALVES
TYPE VS99 PILOT OPERATED
VALVE ASSEMBLY
At the reactor type EPR, three pressurizer safety relief valves type VS99 are mounted directly to
the side of the pressurizer. The inlet is arranged at an angle of 45°. Therefore the valve is installed
in a vertical position. A permanent water loop fills the main and pilot valves, so during blow down
purely sub-cooled water will be relieved first.
Two newly developed type Sierion pilot valves are assigned to one pressurizer safety relief valve.
The Sierion is a non-floating pilot valve which functions well with a wide variety of media such as
steam, water, two-phase flows and supercooled water.
THE EUROPEAN EPR SOLUTION
3 VS99 safety valve
3 x 2 Sierion pilot valve with stop valves for
thepilot and control line
3 x 1 DMS (doubled) bleed and feed valve
Pressurizer
Sierion
Pressurizer relief tank
Sierion Sierion SierionSierion Sierion
Stop valves are attached between the main valve and the pilot valves for the impulse line and pilot
line. Only one pilot valves is active at a time, while the other is blocked by the stop valve.
The Sierion pilot valve is set to a defined set pressure. The response of the main valve under this
set pressure is ensured by activation through a double-solenoid valve type DMS. This is a further
variant of the so-called bleed and feed valve for pressure relief during emergency supply.

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SEMPELL MODEL PSRV - PRESSURIZER SAFETY RELIEF VALVES
TYPE VS99 PILOT OPERATED