METHODS OF CALCULATION FOR THE TREATMENT OF SHIELD HETEROGENEITIES IN THE PROTOTYPE FAST REACTOR.

Technical Report · Fri Oct 31 00:00:00 EST 1969

OSTI ID:4831636

Broughton, J; Butler, J; Brimstone, M; Miller, P C; Packwood, A

The radial shield of the sodium-cooled Prototype Fast Reactor is composed of graphite rods enclosed in steel tubes which are arranged in a lattice of seven rows round the periphery of the breeder. The outside diameter of these rods increases by about a factor of 2 between the inner temperature of about 600 deg C. The dimensions of the steel, graphite and sodium regions are large compared with the mean free paths of the predomination neutrons at intermediate energies; and homogenisation of the shield seriously underestimates the penetration, which is also enhanced by the presence of numerous irregularities associated with nucleonic instrument thimbels, refuelling mechanisms and the primary coolant circuit. Methods of calculation have been developed for the solution of these problems, using both diffusion-theory and Monte Carlo techniques. The diffusion calculations have been accomplished with the COMPRASH and ATTOW codes; and a prototype Monet Carlo code named MOB has been developed, which takes a proper account of the radial shield geometry. The theoretical predictions are compared with measurements made in typical shield arrays on LIDO at Harwell and on the zero-energy fast reactor, ZEBRA, at Winfrith. The diffusion-theory and Monte Carlo approaches are also assessed as design tools taking into consideration accuracy, data preparation and computing time requirements. (auth)

• Research Organization: Nuclear Power Group, Knutsford (England); Atomic Energy Establishment, Winfrith (England)
• NSA Number: NSA-23-013469
• OSTI ID: 4831636
• Report Number(s): AERE-R-5773(Vol.3)
• Resource Relation: Conference: The physics problems of reactor shielding, Harwell (UK), Sep 1967
• Country of Publication: United Kingdom
• Language: English

Related Subjects

N38130* -Power Reactor Development-Shielding
COMPUTERS
CONFIGURATION
DIFFUSION
DIGITAL SYSTEMS
DISTRIBUTION
ERRORS
MONTE CARLO METHOD
NEUTRON FLUX
NEUTRONS
PFR
PROGRAMMING
REACTORS
SHIELDING
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PROTOTYPE FAST REACTOR/shielding for
COMPRASH and ATTOW diffusion programs and MOB Monte Carlo program for neutron distribution in