ML16098A164

Fpra Dependency Analysis

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:

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

- 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

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:

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

- Total value is 0.0084+0.0036+0.0056+0.0024 = 0.02 March 30, 2016 51

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:

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

- 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

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:

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

- Total value is 0.0084+0.0036+0.0056+0.0024 = 0.02 March 30, 2016 51