ML20135H308
| ML20135H308 | |
| Person / Time | |
|---|---|
| Site: | Pilgrim |
| Issue date: | 05/14/2020 |
| From: | Christopher Hunter NRC/RES/DRA/PRB |
| To: | |
| Littlejohn J (301) 415-0428 | |
| References | |
| LER 1993-004-00 | |
| Download: ML20135H308 (9) | |
Text
A.4-5 Sequence p(sequence from p(ADS) p(vent) p(sequence) calculation sheets) 40 4.8 X 10-6
- 1.0 0.01 4.8 X 10-S 48 1.9 X 10-1 1.0 1.0 1.9 X 10-1 55 3.0 X 10-6 0.0 1.0 0
67 9.2 X 10-1 1.0 1.0 9.2 X 10-1 69 2.9 X 10-1 1.0 1.0 2.9 X 10-1 83 3.2 X 10-6 1.0 1.0 3.2 X 10-6 Total 4.6 X 10-6 No analytical evaluation was made of potential consequences of the RV repressurization that occurred during this event.
A. 4. 5 Analysis Results The conditional core damage probability estimated for this event is 4.6 x 10-6. The dominant core damage sequence is highlighted on the event tree in Fig. A.4.3. Sequence 83 involves a failure to recover power from the EDGs or 23-kV line following the LOOP, and failure to recover offsite power before battery depletion.
Inclusion of the BODG and the 23-kV lines in the model reduces the conditional core damage probability for the event. Inclusion of only the BODG results in a reduction of the conditional core damage probability by a factor of7.5. Inclusion of only the 23-kV line results in a reduction of the conditional core damage_
probability by a factor of 2. 2.
Incorporation of suppression pool venting reduces the conditional core damage probability by a factor of 1.2. It only impacts sequence 40.
LER No. 293/93-004
Fig. A.4.2 Simplified diagram of the Pilgrim electrical distribution system LER No. 293/93-004 A.4-6 Figure removed during SUNSI review.