ANSI ANS 19.11-2017 pdf free download – Calculation and Measurement of the Moderator Temperature Coefficient of Reactivity for Pressurized Water Reactors.
This standard provides guidance and specifies criteria for determining the MTC in water moderated power reactors. Measurement of the isothermal temperature coefficient of reactivity (ITC) at hot zero power (HZP) conditions is covered in American National Standard Reload Startup Physics Tests for Pressurized Water Re- actors, ANSIIANS-19.6.1-1997 [1].1 This stand- ard therefore addresses the calculation of the ITC at HZP and the calculation and measurement of the MTC at power. At present, this standard addresses the calculation and measurement of the MTC only in PWRs, because that is the only type of power reactor currently sited in the United States for which measurement of the MTe is required.
3. Definitions
3.1 Limitations.
The following definitions are of a restricted nature for the purpose of this standard. Other specialized terms are defined in the Glossary of Terms in Nuclear Science and Technology [2].
3.2 Glossary
3.2.1 Definition of Terms at power. A reactor operating state where the core is critical and is producing measurable heat from nuclear fission. axial flux difference (AFD). The power in the top half of the core minus the power in the bottom half, divided by the full power:
The AFD sometimes is referred to as power im- balance. control rod (rod). One or more control mem- bers mechanically attached to a single fixture; for the purposes of this standard, the length of the neutron absorber material in the control member is nearly equal to the length of the fuel in the core; i.e., “full length.” This definition excludes “partial length” control rods. control rod group (bank).
One or more control rods that are inserted or withdrawn simultane- ously during normal operation. differential boron worth (DBW). The change in reactivity per unit change in soluble boron concentration.
Doppler temperature coefficient of reac- tivity (DTC). The change in reactivity per unit change in the fuel temperature. fuel assembly. A grouping of fuel rods or pins which are mechanically or metallurgically joined together in a fixed geometrical arrangement.
fll power.The licensed core thermal powerlevel.
hot zero power (HP).reactor operatingstate where the core is not producing measurableheat from nuclearfission and the primarv coolantsvstem is at the no-load desion temperature andpressure.
isothermal temperature coefficient of reac-tivity (TC).The change in reactivity per unitchange in the fuel and moderator temperaturewhen the fuel and moderator are at the sametemperature.
moderator temperature coefficient of reac-tivity (MTC). The change in reactivity per unitchange in the average moderator temperature.For the purposes of this standard, the MTcincludes all reactivity effects associated with achange in the average moderator temperature,whether direct or indirect. (An alternative defi-nition used in portions of the commercial nuclearindustry limits the reactivity effects to thoseresulting directly from the change inthe aver-age moderator temperature and the associatedchange in the moderator density.)
Npower. Core power, as indicated by exeorenuclear instrumentation (NI).
partial length control rod.One or more con-trol members mechanically attached to a singlefitare- for the DurDoses of this standard theleoth of the neutron absorber material in thecontrol member is a fraction of the length of thefuel in the core: i.e”Dartial lenot”
power coefficient (PC). The change inreactiv-ity per unit change in reactor power, with a con-stant average moderator temperature.
power Doppler coefficient (PDC). Thechange in reactivity per unit change in reactorpower,with a constant moderator temperaturedistribution.ANSI ANS 19.11 pdf download.