0

Full Content is available to subscribers

Subscribe/Learn More  >

Safety and Licensing Aspects of Power Reactor Reactivity Coefficients

[+] Author Affiliations
Nik K. Popov, Victor G. Snell

McMaster University, Hamilton, ON, Canada

Paper No. ICONE20-POWER2012-55243, pp. 221-230; 10 pages
doi:10.1115/ICONE20-POWER2012-55243
From:
  • 2012 20th International Conference on Nuclear Engineering and the ASME 2012 Power Conference
  • Volume 4: Codes, Standards, Licensing, and Regulatory Issues; Fuel Cycle, Radioactive Waste Management and Decommissioning; Computational Fluid Dynamics (CFD) and Coupled Codes; Instrumentation and Controls; Fuels and Combustion, Materials Handling, Emissions; Advanced Energy Systems and Renewables (Wind, Solar, Geothermal); Performance Testing and Performance Test Codes
  • Anaheim, California, USA, July 30–August 3, 2012
  • Conference Sponsors: Nuclear Engineering Division, Power Division
  • ISBN: 978-0-7918-4498-4
  • Copyright © 2012 by ASME

abstract

All reactor designs take advantage of favourable inherent characteristics and compensate for unfavourable ones. Because of a very short reactor period for some postulated accidents, the Pressurized Water Reactor (PWR) design requires, and possesses, large negative values of fuel temperature and moderator temperature reactivity coefficients to ensure that rod ejection accidents can be compensated, and to stabilize reactivity transients from the operating state, which would otherwise be fairly rapid. In contrast, the CANDU design does not require strong negative feedback, given the small values of the reactivity coefficients around the operating point and the low reactivity worth of the control devices, both individually and collectively. Even for positive reactivity insertions near prompt critical, the rate of increase in reactor power in a CANDU reactor is inherently limited by its relatively long prompt neutron lifetime (about 40 times longer than that in a PWR), so that the reactor period is much longer and the rate of rise in power and enthalpy is much slower. Consequently, control and shutdown mechanisms are a practical and effective means for reducing total reactivity in the CANDU reactor.

Although there are many international initiatives to align nuclear regulations and hence eliminate nation-specific requirements, many are still design-specific. The regulators who deal primarily with Light Water Reactor (LWR) designs tend to embed the LWR requirement of negative reactor reactivity coefficients in their regulations, whereby the regulations become very design-specific. In contrast, regulators who deal with various reactor designs typically favour a more technology-neutral approach — as in International Atomic Energy Agency (IAEA) standards, stating the safety goals to be achieved rather than defining reactivity coefficients.

This paper presents a comparison of reactivity coefficients between typical modern LWRs and CANDUs. It discusses the relative importance of the reactivity coefficients in reactor safety, identifies major design differences and their influence on the type and value of the reactivity coefficients, and explains key features of the reactor operation and reactor behaviour in transients.

Copyright © 2012 by ASME
Topics: Safety , Licensing

Figures

Tables

Interactive Graphics

Video

Country-Specific Mortality and Growth Failure in Infancy and Yound Children and Association With Material Stature

Use interactive graphics and maps to view and sort country-specific infant and early dhildhood mortality and growth failure data and their association with maternal

NOTE:
Citing articles are presented as examples only. In non-demo SCM6 implementation, integration with CrossRef’s "Cited By" API will populate this tab (http://www.crossref.org/citedby.html).

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In