Parametric Study of Control Rod Exposure for PWR Burnup Credit Criticality Safety Analyses
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
The Interim Staff Guidance on burnup credit (ISG-8) for pressurized water reactor (PWR) spent nuclear fuel (SNF), issued by the Nuclear Regulatory Commission's (NRC) Spent Fuel Project Office, recommends the use of analyses that provide an ''adequate representation of the physics'' and notes particular concern with the ''need to consider the more reactive actinide compositions of fuels burned with fixed absorbers or with control rods fully or partly inserted.'' In the absence of readily available information on the extent of control rod (CR) usage in U.S. PWRs and the subsequent reactivity effect of CR exposure on discharged SNF, NRC staff have indicated a need for greater understanding in these areas. In response, this paper presents results of a parametric study of the effect of CR exposure on the reactivity of discharged SNF for various CR designs (including Axial Power Shaping Rods), fuel enrichments, and exposure conditions (i.e., burnup and axial insertion). The study is performed in two parts. In the first part, two-dimensional calculations are performed, effectively assuming full axial CR insertion. These calculations are intended to bound the effect of CR exposure and facilitate comparisons of the various CR designs. In the second part, three-dimensional calculations are performed to determine the effect of various axial insertion conditions and gain a better understanding of reality. The results from the study demonstrate that the reactivity effect increases with increasing CR exposure (e.g., burnup) and decreasing initial fuel enrichment (for a fixed burnup). Additionally, the results show that even for significant burnup exposures, minor axial CR insertions (e.g., <20 cm) result in an insignificant effect on the keff of a spent fuel cask.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Sponsoring Organization:
- USDOE National Nuclear Security Administration (NNSA), Nuclear Criticality Safety Program (NCSP)
- DOE Contract Number:
- AC05-00OR22725
- OSTI ID:
- 788632
- Report Number(s):
- P01-111328; TRN: US0200534
- Resource Relation:
- Conference: 2001 ANS Embedded Topical Meeting on Practical Implementation of Nuclear Criticality Safety, Reno, NV (United States), 11-15 Nov 2001; Other Information: PBD: 20 Jul 2001
- Country of Publication:
- United States
- Language:
- English
Similar Records
Investigation of the Effect of Fixed Absorbers on the Reactivity of PWR Spent Nuclear Fuel for Burnup Credit
Impact of Integral Burnable Absorbers on PWR Burnup Credit Criticality Safety Analyses
Related Subjects
BURNUP
CONTROL ELEMENTS
CRITICALITY
PWR TYPE REACTORS
SAFETY ANALYSIS
SPENT FUEL CASKS
SPENT FUELS
THREE-DIMENSIONAL CALCULATIONS
TWO-DIMENSIONAL CALCULATIONS
PARAMETRIC ANALYSIS
REACTIVITY
Nuclear Criticality Safety Program (NCSP)
U.S. Nuclear Regulatory Commission (NRC)
Pressurized Water Reactor (PWR)
Spent Nuclear Fuel (SNF)
Control Rod (CR)
Interim Staff Guidance on Burnup Credit (ISG-8)
Axial Power Shaping Rods (APSRs)