Analysis of Main Steam Line Break for a Pressurized Water Reactor

The thermal hydraulics (T-H) code, GINKGO, has been developed by China Nuclear Power Technology Research Institute (CNPTRI) for the transient analyses of pressurized water reactors. GINKGO is designed to simulate the non-loss-of-coolant-accidents (non-LOCAs), and the transients caused by the breaks in secondary side. This paper presents the GINKGO models as well as the analysis of double-ended MSLB that identifies the reactor core characteristics under reactivity feedback. The analysis results show that the variations of reactivity and nuclear power are governed by the competition between positive moderator feedback and negative reactivity insertion by borated water. Finally, the boron concentration is high enough to suppress the nuclear power to a lower power level of ~5%, terminating this reactivity insertion accident (RIA).

Boric Acid Corrosion in the Primary System of PWRs

Borated water leakage could lead to boric acid corrosion of nuclear equipment, and it’s a danger to the pressurized water reactor nuclear power plants (PWRs). In this study, the principle of boric acid corrosion was studied first. Through the experiences of borated water leakages and boric acid corrosion at home and abroad, the main leakage sources in PWRs were summarized. Combining the technique features of visual inspection, the detecting principles were proposed. In the end, a protection strategy of boric acid corrosion was established including the control of borated water leakage, the detection of equipment, the treatment of leakages and the improvement of the equipment material.

Pool Boiling Heat Transfer of Borated (H3BO3) Water on a Nanoporous Surface

With regard to potential application in pressurized water reactors (PWRs), a nanoporous heated surface was tested in pool boiling of an aqueous solution of boric acid (H3BO3), or borated water (1% volume concentration). The effect of system pressure and surface orientation on pool boiling heat transfer (BHT) was studied. The nanoporous surface consisted of a coating of alumina nanoparticles applied on a 1 cm2 flat copper surface through nanofluid boiling. An uncoated surface in borated water was similarly tested, and due to boric acid deposition, the BHT degraded and the critical heat flux (CHF) enhanced relative to pure water. Also, the possibility of transient pool boiling behavior of borated water was investigated but none was detected. With pressure and orientation variation, the nanoporous surface imposed on borated water showed a trend of further CHF enhancement to the CHF limit produced by the nanoporous surface in pure water. Over the nanoporous surface, the CHF of borated water was increasingly better with decreasing pressure, than that over the plain surface. However, BHT degraded slightly further. Boric acid deposition over the nanoporous surface was believed to be the source of this BHT degradation, but played no apparent role in the further CHF enhancement.

Pool Boiling Heat Transfer of Borated (H3BO3) Water on a Nanoporous Surface

With regard to potential application in pressurized water reactors (PWRs), a nanoporous heated surface was tested in pool boiling of an aqueous solution of boric acid (H3BO3), or borated water (1% volume concentration). The effect of different system pressures and different surface orientations on pool boiling heat transfer was studied. The nanoporous surface consisted of a coating of alumina nanoparticles applied on a 1 cm2 flat copper surface through nanofluid boiling. An uncoated surface in borated water was similarly tested, and due to boric acid deposition, the boiling heat transfer (BHT) degraded and the critical heat flux (CHF) enhanced relative to pure water. Also, the possibility of transient pool boiling behavior of borated water was investigated but none was detected. For all pressures and orientations, the nanoporous surface further enhanced the CHF of borated water to the CHF produced by the nanoporous surface in pure water. Over the nanoporous surface, the CHF of borated water was increasingly better with decreasing pressure, than that over the plain surface. However, BHT degraded slightly further. Boric acid deposition over the nanoporous surface was believed to be the source of this BHT degradation, but played no apparent role in the further CHF enhancement.