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Effective void fraction for a BWR assembly with boiling in the bypass region

Technical Report:

Abstract

Average BWR assembly cross-sections for nominal conditions, namely for zero bypass void, can be utilised in the analysis of transient conditions with boiling in the bypass. A model is developed to yield an effective channel void for such conditions. The use of this void in conjunction with the `nominal conditions` cross section library approximately preserves the assembly K-infinity corresponding to the true channel and bypass voids. The effective void is an augmentation of the actual channel void. The augment is proportional to the bypass-to-channel volume ratio, to the bypass void, and to a weight W which is introduced to quantify the fact that a water molecule in the bypass has a different assembly criticality worth than one in the channel. The formula developed is superior to the practice of choosing W=1, namely a simple, non-weighted, transfer of water from channel to bypass. The use of this approximate effective channel void reproduces actual K-infinity values of assemblies to better than 5 mk, whereas the use of a simple model sometimes misspredicts the assembly K-infinity by 40 mK. The effective void model cannot handle cases in which both channel and bypass void value are high, simply because then the effective void {alpha}{sub  More>>
Authors:
Galperin, A; Segev, M; [1]  Knoglinger, E [2] 
  1. Ben-Gurion Univ. of the Negev, Beersheba (Israel)
  2. Paul Scherrer Inst. (PSI), Villigen (Switzerland)
Publication Date:
Sep 01, 1991
Product Type:
Technical Report
Report Number:
PSI-108; STARS-5.
Reference Number:
SCA: 210100; PA: AIX-23:011953; SN: 92000638077
Resource Relation:
Other Information: PBD: Sep 1991
Subject:
21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS; BWR TYPE REACTORS; VOID FRACTION; BYPASSES; BOILING; EIGENVALUES; PRESERVATION; CROSS SECTIONS; DANCOFF CORRECTION; FUEL ASSEMBLIES; MATHEMATICAL MODELS; THEORETICAL DATA; TRANSIENTS; 210100; POWER REACTORS, NONBREEDING, LIGHT-WATER MODERATED, BOILING WATER COOLED
OSTI ID:
10111431
Research Organizations:
Paul Scherrer Inst. (PSI), Villigen (Switzerland)
Country of Origin:
Switzerland
Language:
English
Other Identifying Numbers:
Other: ON: DE92613804; TRN: CH9100672011953
Availability:
OSTI; NTIS (US Sales Only); INIS
Submitting Site:
CHN
Size:
90 p.
Announcement Date:
Jun 30, 2005

Technical Report:

Citation Formats

Galperin, A, Segev, M, and Knoglinger, E. Effective void fraction for a BWR assembly with boiling in the bypass region. Switzerland: N. p., 1991. Web.
Galperin, A, Segev, M, & Knoglinger, E. Effective void fraction for a BWR assembly with boiling in the bypass region. Switzerland.
Galperin, A, Segev, M, and Knoglinger, E. 1991. "Effective void fraction for a BWR assembly with boiling in the bypass region." Switzerland.
@misc{etde_10111431,
title = {Effective void fraction for a BWR assembly with boiling in the bypass region}
author = {Galperin, A, Segev, M, and Knoglinger, E}
abstractNote = {Average BWR assembly cross-sections for nominal conditions, namely for zero bypass void, can be utilised in the analysis of transient conditions with boiling in the bypass. A model is developed to yield an effective channel void for such conditions. The use of this void in conjunction with the `nominal conditions` cross section library approximately preserves the assembly K-infinity corresponding to the true channel and bypass voids. The effective void is an augmentation of the actual channel void. The augment is proportional to the bypass-to-channel volume ratio, to the bypass void, and to a weight W which is introduced to quantify the fact that a water molecule in the bypass has a different assembly criticality worth than one in the channel. The formula developed is superior to the practice of choosing W=1, namely a simple, non-weighted, transfer of water from channel to bypass. The use of this approximate effective channel void reproduces actual K-infinity values of assemblies to better than 5 mk, whereas the use of a simple model sometimes misspredicts the assembly K-infinity by 40 mK. The effective void model cannot handle cases in which both channel and bypass void value are high, simply because then the effective void {alpha}{sub ch}{sup eff} becomes meaningless. A method to treat the {alpha}{sup eff}>1 domain is developed by which corrections to cross sections are provided. Such corrections are synthesised as functions of the assembly parameters. (author) figs., tabs., refs.}
place = {Switzerland}
year = {1991}
month = {Sep}
}