- 學位論文
TRITON/GenPMAXS/PARCS 計算序列應用於單純UOX與混合MOX燃料的簡易爐心模型
Neutronic Simulations for Simple Core Models using TRITON/GenPMAXS/PARCS Sequence
摘要
TRITON/GenPMAXS/PARCS(TGP)計算序列是個由上游晶格計算和下游爐心模擬組成的程式集，使用TRITON程式中的控制序列T-NEWT或T-DEPL進行晶格計算以獲取所需的截面資料，GenPMAXS程式則是個介面程式，將TRITON產生的截面資料轉檔成PARCS程式所能讀取的PMAXS檔案，而爐心模擬程式PARCS是三維多群節點爐心計算程式，可解決穩態、暫態、多群中子擴散以及 SP3遷移方程等問題。本研究利用這個計算序列去模擬一個簡易的壓水式爐心，該爐心會先以TRITON進行全爐心的遷移計算得到此問題的參考答案，並以此為基礎來與TGP計算序列之結果相比較，藉由這些測試來增加使用經驗和分析此計算序列的優缺點。 測試的結果顯示TGP序列用於單純UOX爐心的模擬，無論是keff、燃料組件功率分布和燃料棒功率分布都有著相當的準確度，其中keff誤差只有18 pcm。另外本研究也發現PMAXS檔在吸收和散射截面的部分有稍做處理，使其數值異於TRITON直接產生的截面數值，另外也了解到產生節點截面的TRITON模型，尤其是邊界條件之設置，對於模擬結果影響的重要性。 不過TGP序列對混合MOX爐心的模擬結果就不如前個案例，因此依據文獻的建議，當考慮周遭環境條件的超晶格TRITON模型產生截面資料，雖然能獲得結果的改善卻也造成功率形狀函數選擇上的兩難，因而轉求使用燃料棒尺度的多能群爐心模擬計算，期望能以此方法解決問題，卻因為一些運行錯誤的緣故，未能產出模擬結果，所以先測試燃料組件尺度的多能群計算，在無限大爐心下有著還不錯的結果，但對於單純UOX爐心之結果就不如預期，目前只知道部分誤差源自於未考量up-scattering截面，剩餘部分就有待發掘與探討。希望藉由本研究的成果與經驗能讓未來開發本土的爐心節點程式時，有著更堅實的基礎。
並列摘要
TRITON/GenPMAXS/PARCS sequence is a set of programs which is composed of lattice calculation code and core simulator. TRITON provides cross section datas by lattice calculations. GenPMAXS is an interface program between lattice physics codes and the core simulator. PARCS is a 3-D reactor core simulator which solves the steady-state, transient and multi-group neutron diffusion and SP3 transport equations. First, this TGP sequence simulates a simple PWR core and gets the results. The results will compare with the reference which is calculated by full-core transport calculation. This study aims to increase the use of experience and explore the advantages and limitations of this TGP sequence and provides the information of developing a local nodal core simulator. The results show that the keff, fuel assembly relative power and pin power distribution agree with the reference for the case of pure UOX core. The error of keff is about 18pcm. During the calculation, the study also discover that the values of absorption and scattering cross sections in PMAXS file are different from TRITON output and the results also show the importantance that the configurations of TRITON model and the setting of boundary conditions for generating cross section datas will have the huge impact on the results. However, the results for the case of mixed MOX core don’t present such well as the case of pure UOX core. Therefore, based on the paper review, this study introduces an supercell TRITON model to improve the cross section datas used in the core calculation. Although the results become better, there is a dilemma of the selection of power form functions. The study continues simulating this case with the multi-group, pin-wise calculation. Unfortunately, due to the runtime error, the results can not be produced. And the results of multi-group calculation test still have some problems so that further investigations are ongoing to clarify the cruxes of the problem.