沸水式核反應器穩定性分析之LAPUR方法論發展與驗證

此一論文主要目的，在於以頻域程式—LAPUR為主體並結合相關程式，發展一套以此程式處理沸水式核反應器穩定性的控制機制、理論模式與分析方法。首先，本研究進行國內外文獻之蒐集，而後對現有的研究方法、法規與爐心裝填分析做歸納、探討與驗證，並參考國外對於異常事件的研究與討論，確立穩定性分析之特質。此外，透過對LAPUR模分析程式中，中子理論及熱流理論的瞭解，架構出頻域分析的基礎模式，並歸納建立LAPUR5.2程式之方法論。此一方法論之建立，乃是利用LAPUR5.2程式並結合其他相關程式的分析模式，經過核一廠、核二廠爐心核燃料重新裝填之平行驗證已確認其準確性。因而建立標準的分析工作流程，並確認此方法論的可行性，推廣至核四廠的爐心核燃料裝填分析。此外沸水式反應器需建立穩定運轉邊界，以避免不穩定事件發生﹔經由研究發現針對在穩定邊界上的功率/流量點所做的參數靈敏度分析，以熱流相關參數而言，壓力與流量在高功率/流量點會具有較大的變異性，而中子相關參數則是以密度反應度係數與遲延中子分數高功率/流量點會具有較大的變異性。此外這些重要參數，也會因軸向功率形狀與爐心功率震盪形式之不同而有截然不同的結果，這些分析經驗與心得可供核電廠之管制單位與相關研究機構參考。

關鍵字

沸水式反應器；穩定性分析；參數靈敏度分析；穩定邊界

並列摘要

The purpose of this research which uses a frequency domain code- LAPUR to investigate the controlling mechanisms is to develop analysis methodology for operational instabilities in nuclear boiling water reactor (BWR). This research initially collected the relevant literatures, and then summarized their approaches and regulations. By referring to the studies and discussions on abnormal events, the characteristics of stability analysis have been constructed. We have established LAPUR5.2 methodologies based on the frequency domain code LAPUR5.2 where coupling between neutronic and thermal-hydraulic behaviors are considered. Meanwhile, we have also completed the parallel verifications against vendor’s results for Chinshan (BWR4) and Kuosheng (BWR6) reload design and extended to check Lungmen (ABWR) load design. Sensitivity analyses on various important parameters have been conducted for comparisons. To quantify the effects of various conditions on the global mode and the regional mode, this study employs the reduced-order model and conducts a study of the fractional change in the decay ratio to evaluate the parametric effect of instability on the stability boundary. With respect to global and regional mode parametric sensitivity, density reactivity coefficient, system pressure, delayed-neutron fraction and total core flow and recirculation loop gain were associated with larger fractional changes of decay ratios at points of higher power/flow operation.

並列關鍵字

Boiliing Water Reactor ； Stability Analysis ； Parametric Sensitivity Analysis ； Stability Boundary

參考文獻

Out-Of-Phase Power Instabilities in Boiling Water Reactors,” Nuclear

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4. Park, G. C., Podowski, M. Z. Becker, M. and R. T. Lahey, Jr., 1986, The Development of a Closed-Form Analytical Model for the Stability Analysis of Nuclear-Coupled Density Wave Oscillations in BWR, Nucl. Eng. Des., Vol. 92, pp. 253-281.

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6. Van Der Hagen, T.H.J.J., D.D.B. Van Bragt, F.J. Van Der Kaa, 1997, Exploring the Dodewaard Type-I and Type-II Stability; From Start-Up to Shut-down, From Stable to Unstable, Ann. Nucl. Energy, Vol. 24 No. pp.659-669.

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沸水式核反應器穩定性分析之LAPUR方法論發展與驗證

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