Analysis of Boron Dilution Transients in PWRs.

Diamond, D. J. ; Bromley, B. P. ; Aronson, A. L.

Technical Information Center Oak Ridge Tennessee

关键词: Boron;    Transients;    Thermal analysis;    Reactor safety;    Probability;   

RP-ID  :  DE200415006979

学科分类：工程和技术（综合）

美国|英语

来源: National Technical Reports Library

【 摘 要 】

A study has been carried out with PARCS/RELAP5 to understand the consequences of hypothetical boron dilution events in pressurized water reactors. The scenarios of concern start with a small-break loss-of-coolant accident. If the event leads to boiling in the core and then the loss of natural circulation, a boron-free condensate can accumulate in the cold leg. The dilution event happens when natural circulation is re-established or a reactor coolant pump (RCP) is restarted in violation of operating procedures. This event is of particular concern in B&W reactors with a lowered-loop design and is a Generic Safety Issue for the U.S. Nuclear Regulatory Commission. The results of calculations with the reestablishment of natural circulation show that there is no unacceptable fuel damage. This is determined by calculating the maximum fuel pellet enthalpy, based on the three-dimensional model, and comparing it with the criterion for damage. The calculation is based on a model of a B&W reactor at beginning of the fuel cycle. If an RCP is restarted, unacceptable fuel damage may be possible in plants with sufficiently large volumes of boron-free condensate in the cold leg.