Substitution of the soluble boron reactivity control system of a pressurized water reactor by gadolinium burnable poisons

Journal Article · Sat Nov 01 04:00:00 EST 1986 · Nucl. Technol.; (United States)

OSTI ID:5112082

Galperin, A; Segev, M; Radkowsky, A

The results are presented of a research project that is aimed at designing a gadolinium burnable poison (BP) system for complete reactivity control of a pressurized water reactor (PWR) core during the ''equilibrium'' cycle, resulting in the elimination of the soluble boron system, which represents a considerable saving in both capital and operating costs. A flat and strong negative moderator temperature coefficient is assured for a poison-free moderator. The design analysis of a core, heavily loaded with gadolinium BP rods, was based on a BGUCORE neutronic package and cluster model of a fuel assembly. The project objective was achieved by a novel lumped BP rod, designed as an annulus of gadolinium, clad by zirconium, and inserted into vacant guide thimbles of fresh-fuel assemblies. Specific combinations were found for the inner/outer radii of the poison ring, gadolinium densities, and number of rods per assembly, resulting in an almost flat criticality curve during the cycle. A reactivity swing of approx. =1% ..delta..K can be easily controlled by an existing system of control rods. Comparison of the fuel cycle length of a gadolinium-controlled core with that of the reference, soluble, boron-controlled core indicated that there is no penalty due to residual poison at end of life. Unique guidelines for the fuel loading strategy were applied to find a practical fuel-shuffling scheme by which the design and operational constraints of a typical PWR core of current design were satisfied. Several problems should be solved for a practical implementation of the presented design relative to operational and safety requirements of the existing control rod system. Adequate movement of the regulating rods should be determined and shutdown margins of the safety rods should be ascertained. Final judgment of the feasibility of the concept may be made following the solution of these and other regulatory-related issues.

• Research Organization: Ben-Gurion Univ. of the Negev, Nuclear Engineering Dept., Beer-Sheva
• OSTI ID: 5112082
• Journal Information: Nucl. Technol.; (United States), Journal Name: Nucl. Technol.; (United States) Vol. 75:2; ISSN NUTYB
• Country of Publication: United States
• Language: English

Related Subjects

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS
210200* -- Power Reactors
Nonbreeding
Light-Water Moderated
Nonboiling Water Cooled
B CODES
BORON
BURNABLE POISONS
CAPITALIZED COST
CLADDING
COMPUTER CODES
COMPUTER-AIDED DESIGN
CONTROL ELEMENTS
COST
CRITICALITY
DENSITY
DEPOSITION
ELEMENTS
EQUILIBRIUM
FUEL ASSEMBLIES
FUEL CYCLE
GADOLINIUM
MATERIALS
METALS
MODERATORS
NEUTRON ABSORBERS
NUCLEAR POISONS
OPERATING COST
PHYSICAL PROPERTIES
PWR TYPE REACTORS
RARE EARTHS
REACTIVITY
REACTOR COMPONENTS
REACTOR CORES
REACTOR FUELING
REACTOR MATERIALS
REACTOR SAFETY
REACTOR SHUTDOWN
REACTORS
RECOMMENDATIONS
RESEARCH PROGRAMS
SAFETY
SEMIMETALS
SHUTDOWNS
SOLUBILITY
SURFACE COATING
TRANSITION ELEMENTS
WATER COOLED REACTORS
WATER MODERATED REACTORS
ZIRCONIUM