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4.1. LIGHT-WATER REACTORS
J. C. Cleveland
Oak Ridge National Laboratory
If an alternate cycle such as the denatured cycle is to have a significant early impact,
it must be implemented in LGIRs already operating in the United States or soon to be operating.
The current national LWR capacity is about 48 GWe and LWRs that will provide a total capacity
of 150 to 200 GWe by 1990 are either under construction or on order. Much of the initial
analyses of the denatured 233U fuel cycle has therefore been performed for current LWR core
and fuel assembly designs under the assumption that subsequent to the required fuels development
and demonstration phase for thoria fuels these fuels could be used as reload fuels for operating
LWRs. It should be noted, however, that these current LWR designs were optimized to minimize
power costs with LEU fuels and plutonium recycle, and therefore they do not represent optimum
designs for the denatured cycle. Also excluded from this study are any improvements in reac-
tor design and operating strategies that would improve in-situ utilization of bred fuel and
reduce the nonproductive loss of neutrons in LWRs operating on the once-through cycle. Studies
to consider such improvements have recently been undertaken as part of NASAP (Nonproliferation
A1 ternative Systems Assessment Program).
4.1.1. Pressurized Water Reactors
Mass flow calculations for PWRs presented in this chapter were performed primarily
by Combustion Engineering, with some additional results presented from ORNL calculations.
The Combu'stion Engineering System 80TM (PWR) design was used in all of these analyses. A
description of the core and fuel assembly design is presented in the Combustion Engineering
Standard Safety Analysis Report (CESSAR) . The following cases have been
Dispersible Resource-Based Fuels
A.
B.
LEU (i.e., low enriched uranium, -3% 235U in 238U), no recycle.
MEU/Th (i.e., medium-enriched uranium, 20% 235U in 238U, mixed with 232Th),
no recycle.
C. LEU, recycle of uranium only, 235U makeup.
D. MEU/Th, recycle of uranium (235U + 233U), 20% 235U makeup.*
Dispersible Denatured Fuel
E. Denatured 233U (i,e., -12% 233U in 238U, mixed with 232Th), recycle of uranium,
233U makeup.
*An alternate case utilizing 93% 235U as a fissile topping for recovered recycle uranium and
utilizing 20% 235U as fresh makeup is also discussed by Combustion Engineering.
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