ML110670526
| ML110670526 | |
| Person / Time | |
|---|---|
| Site: | Columbia  |
| Issue date: | 03/04/2011 |
| From: | Dan Doyle Division of License Renewal |
| To: | Mostala A Energy Northwest |
| References | |
| Download: ML110670526 (3) | |
Text
Doyle, Daniel From:
Doyle, Daniel Sent:
Friday, March 04, 2011 12:34 PM To:
'Mostala, Abbas A.'
Cc:
'Tansy II, James L.'; 'Williams, Lisa L.'
Subject:
RE: Proposed Response to Clarification Question 11-urgent action Categories:
- Abbas, The reviewers have looked over your proposal and they believe it will adequately address their concerns.
They are not asking for another call to discuss this.
Their only comment was to add "/CR" to NUREG-6850 as shown in red below:
Considerable discussion was held on whether the existing sensitivity cases provided in Table 2-2 were bounding. Although a difference of opinion existed, it was agreed that additional cases would be performed.
To add additional confidence that NEI 05-01 use of the 95th percentile uncertainty factor sufficiently bounds the parametric uncertainty associated with hot short probabilities, the above 14 cases will be added to Table 2-
- 2. The above 14 cases include FR-08, FR-11R, CC-24R, FW-05R and OT-09R which are cost beneficial in Table B-8. The Staff requested these also be included to see the degree of increase that might occur. The intent of the sensitivity will be to determine the Delta CDF Factor increase that occurs with an enhanced model that contains hot short probabilities consistent with NUREG/CR-6850 guidance or if the circuit has not been evaluated for control power transformers a probability of 0. 6 will be used for that circuit's hot short probability.
For these additional 14 sensitivity cases, the model will be enhanced as described in Section 2.2 of Attachment
- 3. If the delta CDF factor increase exceeds the 95th percentile uncertainty factor for a particular SAMA candidate, the candidate will be further evaluated to determine if the increase is sufficient to alter the conclusion of cost beneficial state as provided in Table B-8 of Attachment 3.
I believe we now have a path forward for resolution of all of the SAMA issues. Please send me your your notes from the 2/28 conference call for the call summary. Please indicate which, if any, you believe were resolved during the call. I will transmit the draft RAIs as official RAIs as soon as I clarify which comments were resolved during the call and which need to be issued as official RAIs. Can you provide an estimate for when you would be able to submit your responses?
Dan Doyle Project Manager Division of License Renewal U.S. Nuclear Regulatory Commission daniel.doyle@nrc.gov (301) 415-3748 From: Doyle, Daniel Sent: Wednesday, March 02, 2011 7:12 AM To: 'Mostala, Abbas A.'
Cc: Tansy II, James L.; Williams, Lisa L.
Subject:
RE: Proposed Response to Clarification Question 11-urgent action
- Abbas, Ok, thanks. I will forward this to the reviewers. I will let you know if they have any feedback or think we need another call to discuss this.
1
Dan Doyle Project Manager Division of License Renewal U.S. Nuclear Regulatory Commission daniel.doyle@nrc.gov (301) 415-3748 From: Mostala, Abbas A. [1]
Sent: Tuesday, March 01, 2011 11:50 PM To: Doyle, Daniel Cc: Tansy II, James L.; Williams, Lisa L.; Mostala, Abbas A.
Subject:
FW: Proposed Response to Clarification Question 11-urgent action Hello Dan, Please find below, Energy Northwest proposed response to NRC question number 11.
- Regards, Abbas NRC Clarification Question No. 11 asked the following:
Section 2.2 provides a sensitivity analysis of the assumed 0.3 hot short probability (if CPTs were known to be present for the circuits; otherwise, 0.6) for three selected SAMAs that address fire events. The basis for selecting the three SAMAs is the RRW significance of the hot shorts they address and that they address numerous important functions. Clarify Energy Northwest's basis for believing that the sensitivity analysis results for these three SAMAs bound the effect for other fire SAMAs. In the response, specifically address the potential for multiple hot shorts in series and whether the factor of 2 impact determined for SAMA FR-07b is bounding for the fire SAMAs.
Alternatively, specifically assess the impact of using a 0.6 hot short probability (or 0.3 if these circuits are known to be protected by CPTs) on the analysis results for fire-related SAMAs FR-08, FR-09R, FR-12R, and FR-11R.
Also, the hot short probability assumption could result in an underestimate of the estimated risk reduction for SAMAs identified principally to address internal events if the SAMA addresses cutsets that contain hot shorts. Assess the impact of using a 0.6 hot short probability (or 0.3 if these circuits are known to be protected by CPTs) on the analysis results for non-fire-related SAMAs AC/DC-1 5, AC/DC-23, AC/DC-27, CC-02, CP-01, CW-02, CW-07, CC-24R, FW-05R, and OT-09R, which have significant fire risk reduction contribution to the total estimated benefit.
Proposed Response to Clarification Question No. 11:
Considerable discussion was held on whether the existing sensitivity cases provided in Table 2-2 were bounding. Although a difference of opinion existed, it was agreed that additional cases would be performed. To add additional confidence that NEI 05-01 use of the 95th percentile uncertainty factor sufficiently bounds the parametric uncertainty associated with hot short probabilities, the above 14 cases will be added to Table 2-2. The above 14 cases include FR-08, FR-11R, CC-24R, FW-05R and OT-09R which are cost beneficial in Table B-8. The Staff requested these also be included to 2
see the degree of increase that might occur. The intent of the sensitivity will be to determine the Delta CDF Factor increase that occurs with an enhanced model that contains hot short probabilities consistent with later NUREG 6850 guidance or if the circuit has not been evaluated for control power transformers a probability of 0.6 will be used for that circuit's hot short probability. For these additional 14 sensitivity cases, the model will be enhanced as described in Section 2.2 of Attachment
- 3.
If the delta CDF factor increase exceeds the 95th percentile uncertainty factor for a particular SAMA candidate, the candidate will be further evaluated to determine if the increase is sufficient to alter the conclusion of cost beneficial state as provided in Table B-8 of Attachment 3.
///////////////////////////////////////////////////////////////////// The End 3