ML15070A563
| ML15070A563 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 03/18/2015 |
| From: | James Shea Tennessee Valley Authority |
| To: | Farideh Saba Plant Licensing Branch II |
| Saba F DORL/LPL2-2 301-415-1447 | |
| References | |
| Download: ML15070A563 (12) | |
Text
Discussion of RAI5-1 Doug Pollock Program Manager Nuclear Safety Analysis March 18, 2015
Introduction Doug Pollock - TVA Nuclear Safety Analysis Gerry Doyle - BFN EPU Director Dan Green - BFN EPU Licensing Manager Pete Donahue - BFN EPU Engineering Manager Gordon Williams - TVA Corporate Licensing PLACE THE TITLE OF THE PRESENTATION HERE l 2 TVA Participants
Timeline Discussion of RAI 5-1 l 3 Proposed Tech Spec Change to Revise the Leakage Rate through the MSIVs Timeline NRC issued Notice of Violation EA-11-252 on January 23, 2012 TVA responded to NOV EA-11-252 by letters dated February 22, 2012, September 28, 2012, March 1, 2013, and August 30, 2013.
TVA letter dated August 30, 2013 Documented that the extent of condition review identified a non-conforming / degraded condition with respect to the Alternate Leakage Treatment (ALT) pathway Committed to submitting a License Amendment Request (LAR) to resolve the non-conforming / degraded condition BFN LAR TS-485 was submitted on November 22, 2013 BFN LAR TS-485, Browns Ferry Nuclear Plant Units 1, 2, and 3 - Proposed Technical Specification Change to Revise the Leakage Rate through the MSIVs TVA submitted the Tech Spec change to TS 3.6.1.3, Primary Containment Isolation Valves, to resolve the non-conforming / degraded condition The LAR is a non-voluntary license amendment request required to correct a non-conforming/degraded condition
RIS 2006-04 Discussion of RAI 5-1 l 4
- Any licensee who uses the AEB 98-03 assumptions should provide a justification that the assumptions are applicable to their particular design
- Answered this in RAI 5.d in the original AST submittal (TS-405, ML023450147)
- Used BFN specific inputs
- The choice of an effective settling velocity in any volume should account for the distribution of particle sizes in that volume
- Discussed in RAI 5.e in original AST submittal (TS-405, ML023450147)
- NDQ099920010019 takes this into account (proprietary information)
Concerns with the Sandia Report Discussion of RAI 5-1 l 5 Calculated deposition for Volumes 2 and 3 took into account deposition occurring in Volume 1 None of the analyzed configurations assumed a failure of one of the MSIVs Doesnt account for flow split between turbine and condenser
MSL Diagram Discussion of RAI 5-1 l 6
Deposition in Volumes 2 and 3
- Report says that no credit should be taken for any deposition in Volume 1
- This is consistent with approval of AEB methodology
- Results for Volumes 2 and 3 reflect deposition in Volume 1
- This is inconsistent with currently approved application of AEB 98-03 methodology
- No deposition in Volume 1 will yield higher removal coefficients in Volumes 2 and 3.
- Therefore removal coefficients appear to be overly conservative and would be higher than given in the report.
Discussion of RAI 5-1 l 7
Failure of an MSIV
- Creates one loop with only 1 MSL volume
- Downstream of outboard MSIV
- Volumes 1 and 2 would be in direct communication with the steam dome and wouldnt be credited
- This would result in a larger removal coefficient in Volume 3
- Direct use of Sandia report results would be overly conservative
- Also results in a larger removal coefficient in Condenser Discussion of RAI 5-1 l 8
Flow Split to Condenser or Turbine
- Most other plants will have the majority of the flow to either the condenser or the turbine
- Sandia report reflects this configuration
- Due to identified issues, BFN is proposing nearly a 50/50 split of the flow
- Sandia report does not address this configuration
- Lower flow will result in more deposition Discussion of RAI 5-1 l 9
Comparison of Values
- Proposed flow rates are lower than range in report
- BFN would be more representative of the 95% values
- These values arent as time dependent
- The in between MSIV length is close to the nominal length
- 50% results
- Somewhat time dependent
- Outboard volume is between min and nominal
- Somewhere between 5% and 50% values
- Condenser deposition area is a little less than double of what was assumed in report (418 m2 vs 252 m2)
Other Considerations
- If deposition in Volume 1 was totally ignored, the resulting coefficients are expected to be closer to those obtained using AEB 98-03, except for the > 12 hr time period
- Proposed BFN analysis showed that 92.5% of dose from this release pathway was received by the control room staff before 12 hrs (most limiting criteria)
- 87% of offsite dose (LPZ)
- Current analysis with majority of MSIV leakage to condenser shows the majority of the dose is received after 12 hrs.
Discussion of RAI 5-1 l 11
Summary
- Sandia methodology doesnt adequately represent the configuration of the BFN proposal
- Adjusted removal coefficients for the first 12 hrs based on the Sandia report are expected to be similar to what AEB 98-03 determines
- Majority of dose received for BFN is within first 12 hrs