基于本质安全的反应堆设计路径----李宁

Report
基于本质安全的反应堆设
计路径
李宁
教授,院长
Oct. 2013
经盟国家事故死亡频率
Fatality Frequencies in OECD Countries
• 比较1969-2000间经合组织国家能源事故导致死亡发生频率和死亡率
的曲线。核电系统的结果是根据核电厂中系统专职概率安全评价体系
得到的,它反映的是潜在死亡率。
Comparison of OECD data. Nuclear curve is based on safety assessment.
LNG
Coal
Hydro
Gas
Oil
Nuclear
2
福岛事故突破了纵深防御
Fukushima Breached Defense-In-Depth
3
福岛事故是“黑天鹅”吗?
Is Fukushima Accident a “Black Swan”?
• “黑天鹅”是具备以下三种特征的极
低概率事件 A BLACK SWAN is a highly
improbable event with three principal
characteristics:
核电安全标准大幅提升
公众接受程度快速下降
– 不可预测 It is unpredictable;
– 后果严重广泛 it carries a massive impact;
– 事后人们会编出理由来解释,使之显得
不那么随机,更可预测 and, after the
fact, we concoct an explanation that
makes it appear less random, and more
predictable, than it was.
经盟国家事故死亡频率
Fatality Frequencies in OECD Countries
• 比较1969-2000间经合组织国家能源事故导致死亡发生频率和死亡率
的曲线。核电系统的结果是根据核电厂中系统专职概率安全评价体系
得到的,它反映的是潜在死亡率。
Comparison of OECD data. Nuclear curve is based on safety assessment.
LNG
Coal
Hydro
Nuclear
Gas
Fukushima?
Oil
5
非经盟国家事故死亡频率
Fatality Frequencies in non-OECD Countries
• 比较1969-2000间非经合组织国家能源事故发生导致死亡发生频率和
死亡率的曲线。
Comparison of non-OECD countries. Nuclear is based on Chernobyl data.
Coal
LNG
Hydro
Nuclear
(direct)
Gas
oil
Nuclear
(indirect)
6
核能发展面临的挑战
Challenges in Nuclear Energy Expansion
• 安全:轻水堆有潜在小概率严重事故可能性
Safety: Small but none-zero severe accident
probability
• 经济性:建造成本高、周期长、投资风险大
Economics: High capital costs, long construction time,
large investment risks
7
核能发展面临的挑战
Challenges in Nuclear Energy Expansion
• 可持续性:Sustainability:
– 有限探明廉价铀资源,极低利用率
Limited U resource, very low utilization
– 废物:长寿命放射性
Waste: Long-life radioactivity
• 核扩散:特殊核原料,同位素富集、核燃料再处
理中元素分离技术
Proliferation: Special nuclear materials, enrichment
and reprocessing technologies
8
费米为CP-1建立的多重安全保护
Fermi’s Multiple Safeguard for CP-1 in 1942
• 3套“控制棒” 3 sets of “control rods”
– Primary set for control of chain reaction
– 2nd automatic rod linked to high reading
– 3rd manual control rod heavily weighted,
tied by a rope to be cut by “Safety Control
Rod Axe Man” in emergency (SCRAM)
• “液体控制队” “Liquid-control squad”
– Pouring a Cadmium-salt solution
9
Rickover上将与核海军
Admiral Rickover and Nuclear Navy
• 实现将军的梦想需要高度重视安全
Rickover’s dream required a high regard
for safety
• 核海军的经验帮助打造了美国和世界
的核工业 Trained personnel relied on
experience gained from Nuclear Navy to
build the nuclear industry in the US and
overseas
• 西屋被引进建设 Westinghouse was
recruited
10
美国反应堆安全顾问委员会
Advisory Committee on Reactor Safeguards
• 美国原子能委员会与1948年成立了反应堆
安全防卫咨询委员会 ACRS was established
by AEC in 1948
– defined its purpose as an instrument toward
preventing any future loss of life in regular
industrial operations
– believed a single accident in industrial reactor
could wreck hopes for peaceful atom
– heeded lessons from Industrial Revolution that
the final guide toward safety had to be
experience in actual use
• 1949年美国反应堆试验基地建立 National
Reactor Testing Station was established in
Idaho in 1949
11
反应堆安全研究焦点领域
Focus of Reactor Safety Research
• 厂址 Plant Siting
• 反应堆物理 Reactor
Physics
• 堆芯设计 Core Design
– 燃料元件设计 Fuel
Element Design
– 机械与热工设计
Mechanical and Thermal
Design
– 沸腾传热 Boiling Heat
Transfer
– 热通道 Hot Channel
Considerations
• 反应堆控制 Reactor
Control
• 仪表 Instrumentation
• 水化学 Water Chemistry
• 屏蔽 Shielding
• 安全壳 Containment
• 事故缓解 Accident
Mitigation
12
轻水堆失冷事故的工程化安全防护
Engineered Safeguard for LWR LOCA
• 反应堆停堆保障关停链式核裂变 Reactor trip to provide
positive and continued shutdown of the nuclear chain
reaction
• 应急冷却堆芯防止燃料熔化 Emergency core cooling (ECC)
to prevent or limit fuel melting
• 事故后散热以避免安全壳内压力过高 Post-accident heat
removal (PAHR) to prevent containment over-pressurization
• 事故后减少反应性以降低可能泄漏的放射性材料 Postaccident radioactivity removal (PARR) to reduce the
radionuclide inventory available for release
• 保障安全壳完整性以限制放射性泄漏 Containment integrity
to limit radionuclide release
13
应急堆芯冷却系统(ECCS)
Emergency Core Cooling System (ECCS)
• 1960年代末前,原子能委员会认为安全壳是终极独立
防御线 Prior to end of 1960s, AEC viewed containment
as the final independent line of defense
• 1965-66年“中国症状”辩论聚集堆芯应急冷却系统
“China Syndrome” debates in 1965-66 brought ECCS into
focus
• 监管重心转向采用设计正确的ECCS运行来防止事故恶
化到威胁安全壳的程度 Regulatory focus shifted to a
properly designed and functioning ECCS to prevent
accidents severe enough to threaten containment
• 失冷事故和堆芯应急冷却系统成为轻水堆安全讨论中
的主要话题 LOCA and ECCS have been major topics of
public discussion of LWR safety
14
质疑ECCS完善性和AEC角色
ECCS Integrity and AEC Role Questioned
• 1971年初,在爱达荷测试设施早期设计的ECCS实验中发现失冷事故时
的高压蒸汽阻塞了来自ECCS的注水 Early 1971, tests of early ECCS design
in Semi-Scale Facility at Idaho showed that the high pressure steam in
LOCA blocked the flow of water from ECCS
• 原子能委员会处理ECCS问题并同时担任核能推动者和监管者的双重角
色受到批评 AEC’s handling of ECCS issues and role as both promoter and
regulator of nuclear were criticized
• AEC分成核监管委员会和联邦能源研究委员会(后成为能源部)AEC
was split into NRC and FERC (later to DOE)
• 原子能委员会的反应堆安全研究开发了概率风险评估方法 Probabilistic
Risk Assessment developed in AEC’s “Reactor Safety Study”
• 1979年3月28日,三里岛事故发生 March 28, 1979, TMI accident
occurred
15
三代加核电站设计目标
Generation III+ Plant Design Objectives
• 增加电站安全性 Increased Plant Safety
– 多冗余或非能动 Additional redundancy or passive features
– 减少操作员反应工作,更多时间 Reduced operator actions, more
time
– 降低堆芯损坏和大剂量泄漏风险 Reduced risk of core damage (CMF)
and large release (LRF)
– 堆芯熔化后保持包容系统完整 Severe accident features incorporated
• Maintain containment integrity after core melt
•
•
•
•
降低成本 Reduce Costs – Larger Plant Rating or Simplifications
延长设计寿命 Increased Plant Design Life – 60 years
缩短建造工期 Shorter Construction Schedules
数字化仪控和主控室 Digital I&C and Compact Main Control
Room
16
先进水堆的共同设计特征
Common Design Features in ALWR
• 60年设计寿命 60-year design life
• 4列安全系统 Four-train safety systems
• 高于90%运行因子 More than 90% availability
factors
• 抗击外部撞击 External impact protection
• 全数字化控制系统 Full digital control systems
• 堆芯保存和稳定系统 Core retention and
stabilization system
17
先进水堆技术
Advanced Water Cooled Reactor Technologies
• 全球 Global
–
–
–
–
–
–
–
–
–
–
AP-1000
EPR
WWER-1000/1200
APR-1400
APR-1000
APWR
ABWR
ESBWR
ACR-700/1000
ATMEA
• 中国 China
–
–
–
–
CAP-1400
CAP-1700
ACP1000*
ACPR1000*
18
先进水堆安全系统
ALWR Safety Systems
ALWR
ALWR
Developer
Main Safety Features
非能动安
全系统
Passive
Safety
System
AP-1000
CAP-1400
Westinghouse
SNPTC
All passive safety system: residual heat
removal, safety injection, containment
cooling
ESBWR
GE
Gravity-driven ECCS, passive containment
cooling system
能动安全
系统
Active
Safety
System
EPR
Areva
4x100% independent Safety train
APR-1400
KHNPC
Improved severe accident mitigation
system, reinforce seismic design basis
ATMEA
Areva
Incl. core catcher
ACR
AECL
APWR
Mitsubishi
Advanced accumulator (passive), refueling
water storage pit in CV
WWER1200
Rosatom
Combined active & passive systems
混合安全
系统
Combined
Safety
System
19
温伯格看反应堆安全
Weinberg on Reactor Safety
• "Atomic power can cure as well as kill. It can
fertilize and enrich a region as well as devastate
it. It can widen man's horizons as well as force
him back into the cave." – in a 1945 Senate
hearing
• “现在的反应堆…充斥着安全系统加
安全系统 – 安全与应急系统几乎主宰
了整个技术 “Reactors are now …
loaded down with safety system
added to safety system – the safety
and emergency systems almost
dominate the whole technology.” –
“Science and Trans-Science”
20
安全与应急系统几乎主宰了核电技术
Safety & Emergency Systems Dominate
• 1350MWe ABWR
21
解决方法
Solution Options
• 核电必须 Nuclear power needs to
– 和其它电力技术竞争 Be competitive with other power
technologies
– 满足苛刻的安全要求 Meet advanced safety requirements
• 用传统技术要同时解决以上问题会很困难
It is very difficult to simultaneously solve these two
problems with the traditional nuclear power
technologies
• 通常以紧凑设计为基础,增加安全系统
Traditionally, developers design reactors for compactness,
then add safety systems
22
从安全基础的角度
Fundamental Safety-based Perspectives
• 反应堆灾害由 Hazards of reactors determined by
– (F.1) 放射性:包含放射性总量 Radiation potential: total
radioactivity (radiotoxicity) stored
– (F.2) 放射性泄漏几率 Probability of radiotoxicity release
– 灾害 Hazards = F.1 x F.2
• 因素1由反应堆功率决定,几乎与堆型无关
F.1 does not depend much of reactor type, but is
determined by total energy output
• 因素2与堆型密切相关
F.2 strongly depends on reactor types
23
设计安全:可能路径
Safety Through Design: Possible Paths
• (P.1) 降低放射性 Reduce radiation potential (F.1)
– Smaller total power
• (P.2) 降低泄漏几率 Reduce probability of release (F.2)
– (P.2.1) Decreased reactivity under abnormal conditions, inherent
negative reactivity feedback
– (P.2.2) Simple and rugged design for key components and
systems
– (P.2.3) Diverse and redundant means for critical safety functions
– (P.2.4) Total stored potential energy
•
•
•
•
(E.1) Nuclear
(E.2) Thermal
(E.3) Chemical
(E.4) Coolant compression
24
安全性分类
Safety Types
• (P.2.1) 固有安全性 Inherent Safety
– 负反应性系数、多普勒效应、控制棒籍助重力落入堆芯等自
然科学法则的安全性,事故时能控制反应堆反应性或自动终
止裂变,确保堆芯不熔化。
Negative reactivity, Doppler effect, control rods drop
into
core under gravity etc, can control reactivity or stop chain
reactions in accidents, ensure no core
melt
• (P.2.2-3) 非能动安全性 Passive Safety
– 建立在惯性原理(如泵惰转)、重力法则(如位差)、热传
递法则等基础上的非能动设备(无源设备)的安全性,即安
全功能的实现毋需依赖外来的动力。
Based on inertia, gravity, heat conduction etc that use no
supplied external power
25
安全性分类
Safety Types
• (P.2.2-3) 能动安全性 Active Safety
– 必须依靠能动设备(有源设备),即需由外部条件加
以保证的安全性。
Rely on active powered equipment and external supplies
• (P.2.2-3) 后备安全性 Redundant Safety
– 指由冗余系统的可靠度或阻止放射性物质逸出的多重
屏障提供的安全性保证。
Based on reliability of redundant systems, or multiple
barriers to prevent release of radioactive materials
26
降低放射性(路径一)
Reducing Radiation Potential (P.1)
• 低功率小型反应堆
Smaller reactors with lower power ratings
• 世界范围有大量的小型堆开发项目
Many SMR (Small Modular Reactor, or Small and
Medium Reactor) development programs worldwide
27
改进燃料以降低事故后果
Improve Fuel to Reduce Consequences
冷却液: 额外储存能量
包壳:间隔燃料和冷却液
燃料:主要放射性和能量源
28
降低势能(路径二之一)
Reducing Potential Energy (P.2.4)
• 核能 Nuclear energy (E.1, see P.1)
• 非核能 Non-nuclear energy (E.2-4)
– 冷却剂固有性质 Inherent coolant property
– 无法工程化去除 Cannot be engineered away
29
冷却水的势能
Potential Energy in Water Coolant
• 热能 Thermal Energy (E.2)
– 通过蒸汽膨胀转化为动能:对设备和包容设施造成机械破坏
Turns into kinetic energy via steam expansion: mechanically
damage equipment & containment
– Evaporation: loss of core cooling
• 化学能 Chemical Energy (E.3)
– 在严重事故中,蒸汽与锆化学反应形成氢气并释放热量,可
能导致氢气爆炸
In severe accidents, steam chemically interacts with zirconium,
releasing more thermal energy and hydrogen, potentially
leading to hydrogen explosion
30
不同冷却剂的势能比较
Stored Potential Energy for Different Coolants
冷却液
Coolant
水
Water
钠
Sodium
铅、铅铋合金
Lead,
Lead-bismuth
Parameters
P = 16 MPa
Т = 300 ºС
Т = 500 ºС
Т = 500 ºС
~ 21,3
~ 10
~ 0,74
Maximal potential
energy, GJ/m3,
Including:
Thermal
energy
including
compression
potential
energy
Potential chemical
energy of interaction
Potential interaction
energy escape
hydrogen with air
~ 0,90
~ 0,15
With zirconium
~ 11,4
~ 9,6
~ 0,53
~ 0,74
None
None
With water 5,1
With air 9,3
None
~ 4,3
None
G. I. Toshinsky, INES-3 (2010)
31
以安全为中心的反应堆设计路线
核电站放
射性危害
决定反应堆与核电站安
全的因素
以安全为基础的反应堆
设计方案
F1: 放射性总量
P1: 降低反应堆功率
与反应堆型相关
的因素
中低功率小型堆
P2.1: 增加固有安全性
燃料/冷却剂
堆芯较易传出中子与热
P2.2: 采用简单可靠的
设计与部件
燃料/包壳/冷却
剂
坚固燃料和包壳
简单结实的小型堆
P2.3: 采用多元冗余的
安全系统
燃料/包壳/冷却
剂
非能动安全性
一体化小型堆
E1: 核能
中低功率小型堆
E2: 热能
惰性包壳和高导热燃料
E3: 化学能
水冷:高
钠冷:中
铅/铅铋/熔盐冷:低
E4: 压缩能
气态冷却剂:高
液态冷却剂:低
P2.4: 降低总储能
H=F1xF2
(S, Q, T,
R)
推论与观察
F2: 泄漏几率
HF: 人因工程
小型堆:简化系统,控
制点少
S: 正确选址
对厂址条件要求较低、
抗震性较高的小型堆
Q: 高质建设
工厂制造:更好的质量
控制和改进
T: 运行前全面检测
简单、易操作的小型堆
R: 独立完善监管
标准系列化产品:监管
一致性高
32
调整风险因子配置
Rebalance Risk Factors
• 反应堆灾害= 后果x频率=F.1 x F.2
• 现行设计理念:通过纵深防御和冗余安全与应急
系统降低频率F.2
• 为降低单位成本,加大反应堆功率和放射性F.1
• 核电最坏事故和后果(超设计基准事故)变得更
为严重极端,降低核电的认可度
• 改变设计理念:平衡风险因子 F.1 和F.2的分布!
33
公众和市场欢迎/可接受的核电
Nuclear Power Welcomed by Public & Market
• 系统安全性保持良好
• 最坏后果范围和持续时间大幅减小
LNG
Coal
Hydro
Gas
未来核
电事故? Nuclear
Oil
34

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