Fig. 1. Radial layout of UPR-s (color online)
Fig. 2. Layout of the UUV system and pressure tank (color online)
Fig. 3. Diagram of shielding region of the UUV
Fig. 4. Neutron energy spectrum of UPR-s under full-power operating conditions
Fig. 5. Calculation results of source intensity after shutdown (a) Neutron source intensity versus time, (b) Photon source intensity versus time
Fig. 6. The spectrum of UPR-s after shutdown (a) Neutron spectrum, (b) Photon spectrum
Fig. 7. Diagram of initial shielding model (color online)
Fig. 8. Two composite shielding models (a) Poly-LiH-W layout scheme, (b) LiH-Poly-W layout scheme
Fig. 9. Calculation results for Poly-LiH-W shielding models (a) Neutron fluence in the safety plane, (b) Photon dose in the safety plane
Fig. 10. Shadow shielding model (color online)
Fig. 11. Calculation results for the shadow shielding model (a) Neutron fluence in the safety plane, (b) Photon dose in the safety plane, (c) Neutron fluence changes with axial coordinates, (d) Photon dose changes with axial coordinates
Fig. 12. Structure of optimized shielding design
Fig. 13. Calculation results for the shielding model under full-power operating conditions (a) Neutron fluence in the safety plane, (b) Photon dose in the safety plane, (c) Neutron fluence changes with axial coordinates, (d) Photon dose changes with axial coordinates
Fig. 14. Calculation results for the shielding model after shutdown (a) Change in maximum dose rate in the safety plane with time, (b) Dose rate in the safety plane after 15 d of shutdown, (c) Dose rate in the safety plane after 15 d of shutdown, (d) Change in dose rate with axial coordinates after 15 d of shutdown
| 参数Parameter | 数值Value |
|---|
| 热功率Thermal Power / MWth | 1 | | 寿期Life / a | 5 | | 热管数目Number of heat pipe | 109 | | 燃料棒数目Number of fuel rod | 480 | | 富集度Enrichment / % | 73/55/19.75 | | 三种UO2燃料棒数目Number of three UO2 fuel rod | 332/108/40 | | 活性区基体材料Active zone matrix material | Mo-0.59W-0.31Ti-0.11Zr-0.01C | | 上下反射层材料Upper and bottom reflector material | BeO | | 保温层厚度Thickness of insulation layer / mm | 3.3 | | 滑动反射层/控制棒数目Number of sliding reflector/ Control rod | 4/4 | | 滑动反射层反射体（跟随体）材料Sliding reflector (follower) material | BeO (Stainless steel) | | 安全棒反射体（跟随体）材料Safety rod reflector (follower) material | BeO (B4C) | | 燃料区外围区域反射层材料Fuel region reflector material | Be | | 反射层外部材料Material outside reflector | B4C | | 活性区体积Volume of active region / L | 93.61 | | 活性区高度Height of active region / mm | 450 | | 反应堆高度Height of reactor / mm | 900 | | 反射层外径Outer radius of reflector / mm | 960 | | 反应堆外径Outer radius of reactor / mm | 1 000 |
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Table 1. Overall design parameters of UPR-s
区域 Regions | 尺寸 Sizes / cm | 材料 Materials | 体积占比 Volume ratio / % |
|---|
活性区（含热管） Active zone (including heat pipe) | Φ25.73×H45 | 73 wt% UO2 | 17.45 | | 55 wt% UO2 | 5.68 | | 19.75 wt% UO2 | 2.10 | | 氦气Helium | 0.86 | | 钼合金Molybdenum alloy | 36.87 | | Na | 10.36 | | Haynes233 | 13.34 | | 真空Vacuum | 13.33 | 上（下）轴向反射层 Upper (lower) axial reflector | Φ25.73×H22.5 -热管Heat pipe | BeO | 92.80 | | 钼合金Molybdenum alloy | 7.20 | 径向反射层 Radial reflector | Φ48×H90 -Φ25.73×H90 | 钼合金Molybdenum alloy | 0.11 | | BeO | 23.06 | | 不锈钢Stainless steel | 2.02 | | Be | 68.75 | | 真空Vacuum | 6.06 | 径向屏蔽层 Radial shielding | Φ50×H90 -Φ48×H90 | B4C | 100.00 | 热管（从活性区外部伸出建模） Heat pipes (outside the active zone) | Φ1.5×H151.5 | Na | 27.98 | | Haynes233 | 36.02 | | 真空Vacuum | 36.00 | 温差发电（区域中心与活性区中心距离为139.5 cm） Thermoelectric power generation (the distance between the center of the area and the center of the active zone is 139.5 cm) | X45×Y49.5×Z114 -热管Heat pipe | Al | 74.16 | | H2O | 6.02 | | 真空Vacuum | 19.82 | 仪器打混 Instrument mix | — | 不锈钢Stainless steel | 10.00 | | 真空Vacuum | 90.00 |
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Table 2. Sizes and materials of different regions
| 材料Material | 作用Function | 密度Density / g·cm-3 |
|---|
| 碳化硼B4C | 中子屏蔽Neutron shielding | 2.22 | | 水Water | 中子屏蔽Neutron shielding | 1.00 | | 铍Be | 中子屏蔽Neutron shielding | 1.85 | | 聚乙烯Polyethylene | 中子屏蔽Neutron shielding | 0.96 | | 氢化锂LiH | 中子屏蔽Neutron shielding | 0.82 | | 钨Wolfram | 光子屏蔽Photon shielding | 19.35 | | 铅Lead | 光子屏蔽Photon shielding | 11.34 | | 不锈钢Stainless steel | 光子屏蔽Photon shielding | 7.80 |
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Table 3. Candidate shielding materials
材料 Material | 安全平面的累积 快中子注量最大值 Maximum cumulative fast neutron fluence in the safety plane / n·cm-2 | 安全平面的累积 光子剂量最大值 Maximum cumulative photon dose at the safety plane / rad | 屏蔽总重量 （加后端聚乙烯） Total weight of shielding plus rear end polyethylene / kg | 堆芯加屏蔽重量 Core and shielding weight / kg |
|---|
| 无（真空）None (vacuum) | 8.31×1013 | 7.42×106 | 755.55 | 2 603.80 | | 碳化硼B4C | 3.27×1011 | 5.18×105 | 1 998.51 | 3 846.76 | | 水Water | 4.78×1011 | 1.49×106 | 1 315.44 | 3 163.70 | | 铍Be | 4.57×1011 | 1.39×106 | 1 791.35 | 3 639.60 | | 聚乙烯Polyethylene | 2.22×1011 | 1.53×106 | 1 294.17 | 3 142.42 | | 氢化锂LiH | 1.93×1011 | 1.57×106 | 1 214.66 | 3 062.91 | | 钨Wolfram | 3.56×1011 | 4.78×104 | 11 589.44 | 13 437.69 | | 铅Lead | 1.18×1013 | 1.49×106 | 7 106.79 | 8 955.04 | | 不锈钢Stainless steel | 6.78×1012 | 7.36×105 | 5 124.49 | 6 972.74 |
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Table 4. Calculation results for the candidate materials
| 材料Material | 安全平面的累积快 中子注量最大值 Maximum cumulative fast neutron fluence in the safety plane / n·cm-2 | 安全平面的累积 光子剂量最大值 Maximum cumulative photon dose at the safety plane / rad | 屏蔽总重量 （加后端聚乙烯） Total weight of shielding plus rear end polyethylene / kg | 堆芯加屏蔽重量 Core and shielding weight / kg |
|---|
| Poly-LiH-W | 1.80×1011 | 9.47×104 | 2 561.76 | 4 410.02 | | LiH-Poly-W | 1.86×1011 | 8.34×104 | 2 608.61 | 4 456.86 |
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Table 5. Calculation results for the two composite shielding models
区域 Area | 几何尺寸 Geometric size / cm | 密度 Density / g·cm-3 | 体积 Volume / cm3 | 数目 Number | 重量 Weight / kg |
|---|
活性区（含热管） Active zone (including heat pipe) | Φ25.73×H45 | — | — | — | 堆芯重量1 848.25 Weight of the core | 上（下）轴向反射层 Upper (lower) axial reflector | Φ25.73×H22.5 -热管Heat pipe | — | — | — | 径向反射层 Radial reflector | Φ48×H90 -Φ25.73×H90 | — | — | — | 径向屏蔽层 Radial shielding | Φ50×H90 -Φ48×H90 | — | — | — | 热管（从活性区外部伸出建模） Heat pipes (outside the active zone) | Φ1.5×H151.5 | — | — | 109 | 不计热管重量 Not count the weight of heat pipes | 前端钨 Front wolfram | Φ50×H0.7 -Φ25.73×H0.7 | 19.35 | 4 041.90 | 2 | 156.42 | 前端聚乙烯 Front Polyethylene | Φ25.73×H0.7 -热管Heat pipe | 0.962 | 1 183.75 | 2 | 2.28 | 聚乙烯① Polyethylene① | R1 25.73×R2 50×H13.6 -热管Heat pipe | 0.962 | 58 068.20 | 2 | 111.72 | 水① Water① | Φ50×H3.6 -热管Heat pipe | 1 | 26 874.75 | 2 | 53.75 | 不锈钢套管① Stainless steel sleeve① | Φ50×H4.2 -Φ50×H3.6 -热管Heat pipe | 7.80 | 4 479.13 | 2 | 69.90 | 聚乙烯② Polyethylene② | R1 50×R2 25.73×H14.3 -热管Heat pipe | 0.962 | 61 057.01 | 2 | 117.47 | 水② Water② | Φ50×H3.6 -热管Heat pipe | 1 | 26 874.75 | 2 | 53.75 | 不锈钢套管② Stainless Steel Sleeve② | Φ50×H4.2 -Φ50×H3.6 -热管Heat pipe | 7.80 | 4 479.13 | 2 | 69.90 | 后端钨 Back end wolfram | Φ50×H0.5 -热管Heat pipe | 19.35 | 3 732.60 | 2 | 144.45 | 温差发电（区域中心与活性区 中心距离为139.5 cm） Thermoelectric power generation (the distance between the center of the area and the center of the active zone is 139.5 cm) | X45×Y49.5×Z114 -热管Heat pipe | — | — | — | 不计 Not count | 后端聚乙烯（壳体内） Back end polyethylene (inside the shell) | Φ50×H15 | 0.962 | 117 809.72 | 2 | 226.67 | 后端聚乙烯（壳体外） Back end polyethylene (outside the shell) | Φ100×H4 -Φ75×H4 | 0.962 | 54 977.87 | 2 | 105.78 | 内壳体 Inner shell | Φ110×H550 -Φ100×H540 | — | — | — | 不计 Not count | 外壳体 Outer shell | Φ150×H550 -Φ140×H550 | — | — | — | 不计 Not count | 海水（双壳体内） Sea water (in double shell) | Φ140×H550 -Φ110×H550 | — | — | — | 不计 Not count | 海水（舱室外） Sea water (outside the cabin) | X240×Y240×Z640 -Φ200×H640 | — | — | — | 不计 Not count | 仪器打混 Instrument mix | 其他区域 Other areas | — | — | — | 不计 Not count | | 总和Sum | X240×Y240×Z640 | — | — | — | 2 960.35 |
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Table 6. Parameters of the optimized shielding design
| 满功率运行时安全平面 的累积快中子注量 Cumulative fast neutron fluence in the safety plane under full-power operation / n·cm-2 | 满功率运行时安全 平面的累积光子剂量 Cumulative photon dose in the safety plane under full-power operation / rad | 停堆条件下，阴影区 总剂量率 Total dose rate in the shaded area under shutdown conditions / mSv·h-1 | 堆芯加屏蔽重量 Core and shielding weight / kg |
|---|
设计要求 Design requirements | ≤ 1012 | ≤ 106 | ≤ 0.007 50 | ≤ 3 000.00 | 最终方案 Final scheme | 9.48×1011 (maximum) | 7.29×105 (maximum) | 0.004 49 (maximum) | 2 960.35 |
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Table 7. Shielding performance of the heat pipe nuclear reactor
