来自 昏昏睡睡HSE · From Drowsy HSE CSP DAILY LEARNING · DAY 177

FTA 与事件树 · 概念解析 | Fault Tree & Event Tree · Core Concepts

第 35 块 · Domain 3 · 风险管理 · 15%Block 35 · Domain 3 · Risk Management · 15%第 1 / 5 课 · 概念解析Lesson 1 of 5 · Core Concepts

本课只做一件事：搞清「FTA 与事件树」到底是什么、为什么考试要先过这一关、它管到哪里为止。

Get clear on what Fault Tree & Event Tree really is, why it comes first, and where it stops.

本课不涉及：不展开细节与题目——那是第 2–5 课的事。
Not covered here: No detail, no questions — those are lessons 2 to 5.

本课目标 | Learning objectives

  1. 能用一句话说清「FTA 与事件树」解决的是什么问题
  2. 能举出一个「不懂它就一定做错」的例子
  3. 知道本课的边界，不把后续课的内容提前混进来

  • State in one sentence the problem Fault Tree & Event Tree solves
  • Give one example where missing it guarantees a wrong answer
  • Know this lesson's boundary and keep later lessons out

    • 图片预览 / Photo preview

    图片经过压缩后保存在当前浏览器。导出失败时，可在下方预览图片上长按保存。/ The photo is compressed and stored in this browser. If download fails, long-press the preview below to save it.

    它是什么 | What it is

    故障树（FTA）自顶向下：从一个不希望的顶事件出发，用 AND 门与 OR 门往下拆到基本事件。AND 门（与门）＝所有输入同时发生才输出，概率近似相乘（更难发生）；OR 门（或门）＝任一输入发生即输出，概率近似相加（注意共因重叠会低估）。最小割集＝导致顶事件的最少基本事件组合。事件树（ETA）自左向右：从初始事件出发，逐道屏障按成功/失败分支，展开成从「安全」到「最坏可信」的结果谱。两者互补：FTA 找组合致因，ETA 评屏障有效性。

    Fault tree analysis works top-down: from an unwanted top event through AND and OR gates to basic events. An AND gate fires only when all inputs occur, so probabilities multiply (rarer); an OR gate fires on any input, so probabilities roughly add — beware common-cause overlap. A minimal cut set is the smallest combination of basic events that produces the top event. Event tree analysis runs left to right: from an initiating event through each barrier's success or failure into an outcome spectrum from safe to worst credible. They complement: FTA finds combined causes, ETA tests barriers.

    为什么先学它 / Why first
    两个坑：①门用反——把「泵失效或阀失效都导致泄漏」画成 AND 门（结果是概率被乘小了 100 倍）；②OR 门支路共因（同一电源、同一程序版本）时按独立相加会低估顶事件概率。
    Two traps: reversing gates — 'pump or valve failure causes the leak' drawn as an AND gate shrinks the probability a hundredfold; and common-cause OR branches sharing a power supply or a code version, where adding as if independent undercounts the top event.
    它管到哪里为止 / Where it stops
    本块不含精确概率计算（互斥/不独立事件的修正公式），只讲近似方法与定性结构。
    Exact probability formulas for mutually exclusive or dependent events are out of scope; approximation and structure only.

    先认个脸 | Terms you will meet

    1. Top Event — 顶事件
    2. AND Gate — 与门
    3. OR Gate — 或门
    4. Event Tree — 事件树
    5. Minimal Cut Set — 最小割集
    6. Barrier — 屏障

    这里只要求认得；定义、易混与例句在本块第 3 课「术语精讲」。/ Recognition only — definitions come in the glossary lesson of this block.

    情景自测 | Scenario check

    本课理解Lesson comprehension

    这道题考什么：考两棵树的分工。
    Tests the division of labour.

    想知道「联锁失效后，围堰与喷淋还能不能兜住泄漏」，该用？

    To learn whether a bund and spray can still hold a leak after an interlock fails, use?

    自编练习题，不是 BCSP 官方真题，也不能用来预测分数。 / Original practice item, not an official BCSP exam question.

    动手练 | Practice

    1. 画一棵三层故障树（顶事件+门+基本事件）。
    Draw a three-level fault tree.

    学习打卡与笔记 | Progress & notes

    已完成 0/4 项 / 0/4 tasks complete

    连续学习 / Learning streak: 0 天 / 0 days

    进度保存在当前浏览器，不会自动跨设备同步。/ Progress is stored in this browser only.

    PNG 学习记录预览；可长按图片保存 / PNG card preview; long-press to save

    可靠来源 | Official references

    BCSP — CSP Examination Blueprint (CSP11)

    BCSP — Official Self-Assessments

    BCSP — Certified Safety Professional (CSP)

    Pearson VUE — CSP 考试预约 / Scheduling

    本课为一般性学习资料，不替代现场专业评估、法规要求或组织程序。/ Educational content only.

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