ML16098A164
| ML16098A164 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley |
| Issue date: | 03/30/2016 |
| From: | FirstEnergy Nuclear Operating Co |
| To: | Plant Licensing Branch 1 |
| Lamb T, NRR/DORL/LPLI-2 | |
| References | |
| Download: ML16098A164 (4) | |
Text
Beaver Valley FPRA Dependency Analysis Sequences compared to minimal cutsets - example
- Consider a non-minimal joint HEP of A-B-C-D
- A-B is the minimal cutset
- C and D are non-consequential - their success or failure does not affect change whether the sequence goes to core damage
- Assume the individual HEP values are
- A = 0.1
- B = 0.2
- C = 0.3
- D = 0.4
- The minimal cutset A-B = 0.02 March 30, 2016 48
Beaver Valley FPRA Dependency Analysis Sequences compared to minimal cutsets - example
- Now consider the sequence results containing this joint HEP
- All possible sequences containing the minimal cutset A-B will be produced, including all combinations of success and failure of the non-minimal HEPs C and D
- RISKMAN will produce the following sequences:
- A=F, B=F, C=F, D=F
- A=F, B=F, C=F, D=S
- A=F, B=F, C=S, D=F
- A=F, B=F, C=S, D=S March 30, 2016 49
Beaver Valley FPRA Dependency Analysis Sequences compared to minimal cutsets - example
- Recalling the way sequences are quantified:
- Summing the sequences, 0.0024+0.0036+0.0056+0.0084=0.02
- This is the same value as the minimal cutset result March 30, 2016 50 ABCD 0.1*0.2*0.3*0.4 0.0024 ABC(1D) 0.1*0.2*0.3*(10.4) 0.0036 AB(1C)D 0.1*0.2*(10.3)*0.4 0.0056 AB(1C)(1D) 0.1*0.2*(10.3)*(10.4) 0.0084
Beaver Valley FPRA Dependency Analysis Dependency analysis - impact of non-consequential HFEs
- If we increase the value of the non-consequential HFEs (C and D) to mimic dependence factor increases, the total value does not change
- Assume new values are C=0.6, D=0.7 (no change to minimal cutset A-B)
- New sequences are:
- Total value is 0.0084+0.0036+0.0056+0.0024 = 0.02 March 30, 2016 51 ABCD 0.1*0.2*0.6*0.7 0.0084 ABC(1D) 0.1*0.2*0.6*(10.7) 0.0036 AB(1C)D 0.1*0.2*(10.6)*0.7 0.0056 AB(1C)(1D) 0.1*0.2*(10.6)*(10.7) 0.0024
Beaver Valley FPRA Dependency Analysis Sequences compared to minimal cutsets - example
- Consider a non-minimal joint HEP of A-B-C-D
- A-B is the minimal cutset
- C and D are non-consequential - their success or failure does not affect change whether the sequence goes to core damage
- Assume the individual HEP values are
- A = 0.1
- B = 0.2
- C = 0.3
- D = 0.4
- The minimal cutset A-B = 0.02 March 30, 2016 48
Beaver Valley FPRA Dependency Analysis Sequences compared to minimal cutsets - example
- Now consider the sequence results containing this joint HEP
- All possible sequences containing the minimal cutset A-B will be produced, including all combinations of success and failure of the non-minimal HEPs C and D
- RISKMAN will produce the following sequences:
- A=F, B=F, C=F, D=F
- A=F, B=F, C=F, D=S
- A=F, B=F, C=S, D=F
- A=F, B=F, C=S, D=S March 30, 2016 49
Beaver Valley FPRA Dependency Analysis Sequences compared to minimal cutsets - example
- Recalling the way sequences are quantified:
- Summing the sequences, 0.0024+0.0036+0.0056+0.0084=0.02
- This is the same value as the minimal cutset result March 30, 2016 50 ABCD 0.1*0.2*0.3*0.4 0.0024 ABC(1D) 0.1*0.2*0.3*(10.4) 0.0036 AB(1C)D 0.1*0.2*(10.3)*0.4 0.0056 AB(1C)(1D) 0.1*0.2*(10.3)*(10.4) 0.0084
Beaver Valley FPRA Dependency Analysis Dependency analysis - impact of non-consequential HFEs
- If we increase the value of the non-consequential HFEs (C and D) to mimic dependence factor increases, the total value does not change
- Assume new values are C=0.6, D=0.7 (no change to minimal cutset A-B)
- New sequences are:
- Total value is 0.0084+0.0036+0.0056+0.0024 = 0.02 March 30, 2016 51 ABCD 0.1*0.2*0.6*0.7 0.0084 ABC(1D) 0.1*0.2*0.6*(10.7) 0.0036 AB(1C)D 0.1*0.2*(10.6)*0.7 0.0056 AB(1C)(1D) 0.1*0.2*(10.6)*(10.7) 0.0024