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Heavy Water Reactors
Published in Kenneth D. Kok, Nuclear Engineering Handbook, 2016
Alistair I. Miller, John Luxat, Edward G. Price, Paul J. Fehrenbach
4.2.1.3.7.1 Feedwater and Main Steam System Feedwater flows from the condenser via the regenerative feedwater heating system and is supplied separately to each steam generator. The feedwater is pumped into the steam generators by feedwater pumps with the flow rate to each steam generator regulated by feedwater control valves. A check valve in the feedwater line of each steam generator is provided to prevent backflow in the unlikely event of feedwater pipe failure. An auxiliary feedwater pump is provided to satisfy low-power feedwater requirements during shutdown conditions, or in the event that the main feedwater pumps become unavailable.
Reliability and Availability of Repairable Components and Systems
Published in Mohammad Modarres, Mark P. Kaminskiy, Vasiliy Krivtsov, Reliability Engineering and Risk Analysis, 2016
Mohammad Modarres, Mark P. Kaminskiy, Vasiliy Krivtsov
The auxiliary feedwater system in a pressurized water reactor (PWR) plant is used for emergency cooling of steam generators. The simplified piping and instrument diagram (P&ID) of a typical system like this is shown in Figure 5.34a.
Risk-Informed Safety Analysis for Accident Tolerant Fuels
Published in Nuclear Science and Engineering, 2020
Carlo Parisi, Zhegang Ma, Diego Mandelli, Nolan Anderson, Hongbin Zhang
The following events are described for each ET branch or SBO scenario of Table I: turbine-driven auxiliary feedwater (TDAFW) availability: yes or nopressurizer (PZR) pilot-operated relief valve (PORV): closed or stuck openrapid secondary-side depressurization (RSD): effectuated by the operator using the steam generator (SG) PORVs. The considered ratio of depressurization is ~55 K/h [100°F/h (Ref. 62)].reactor coolant pump (RCP) seal LOCA: a variable leakage rate [no leakage, 21, 76, 182, 300, and 480 gallons per minute (gpm)] from each of the RCP is assumed.alternating-current (AC) power recovery timeemergency recovery actions after success or failure of AC recovery and loss of direct-current (DC) power: manual control of the auxiliary feedwater (AFW-MAN), manual SG depressurization, late off-site power recovery (OPR), high-pressure injection (HPI), high-pressure injection - recirculation mode (HPR), low-pressure injection - recirculation mode (LPR).
Conceptual Design of an Accident Prevention System for Light Water Reactors Using Artificial Neural Network and High-Speed Simulator
Published in Nuclear Technology, 2020
In Fig. 3 simulation of the recovery incorporating the FLEX strategy for a PWR after SBO shutdown condition is presented. The recovery starts with the turbine-driven auxiliary feedwater pump drawing water from the condensate storage tank (CST). Steam is boiled off to the atmosphere. The tank could be refilled by a fire truck, and with this water supply the core decay heat could be removed in hot shutdown conditions indefinitely. Should this passive cooling be lost or cold shutdown be desired, forced depressurization of the primary can be initiated. This is achieved by opening the pressure relief valve and activating the alternate AC supply to power the HPI pumps. In this case the decay heat is removed from the core but the containment will be pressurized. As a result, the containment spray will be activated. All of the above actions rely upon the operators to implement the FLEX strategies using alternate power and water sources.
Potential Recovery Actions from a Severe Accident in a PWR: MELCOR Analysis of a Station Blackout Scenario
Published in Nuclear Technology, 2018
J. Wang, H. J. Jo, M. L. Corradini
In our previous work, we analyzed a station blackout (SBO) sequence for the Surry pressurized water reactor (PWR) and examined the effect of a loss of auxiliary feedwater (AFW) with the MELCOR systems analysis computer code.10 FeCrAl oxidation kinetic11,12 and some sensitivities were also done in separate work.12,13 In this work, we confirmed the general accident progression with prior studies14 and analyzed the effect of replacing Zircaloy cladding with a proposed FeCrAl alloy.10,15 During this simulation, cladding properties (enthalpy, heat capacity, thermal conductivity, density, melting temperature, latent heat of fusion, and metal-steam oxidation rate) for FeCrAl cladding were modified in MELCOR. When FeCrAl is substituted for Zircaloy to examine its performance, we confirmed that FeCrAl noticeably slows the accident progression (Fig. 1) and reduces the amount of hydrogen generated.5,6,16–18