Emerson Sempell PSRV VS99, Руководство пользователя

Страница: 3 / 38

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).