ML092090773
| ML092090773 | |
| Person / Time | |
|---|---|
| Site: | River Bend  |
| Issue date: | 07/28/2009 |
| From: | Entergy Operations |
| To: | Plant Licensing Branch IV |
| References | |
| TAC ME1507, TAC ME1508 | |
| Download: ML092090773 (27) | |
Text
Cf)~
Z 0::
(l)
" ~ en Cf)~
-c (l)
(l)-c E 0
,--0 S
c c
0
.:::t::.-C en (l) en 0:: co CO
RI lSI
Background
- RBS Submittal dated June 16, 2009
- Requested approval date - December 2010
- RF-16 begins early 2011
- RI lSI Relief Requests based upon Code Case N-716 have a common template
- Submittal template based upon Grand Gulf pilot submittal dated September 22, 2006
RI lSI
Background
- Used prior submittals as guidance in development of RBS submittal
- Followed Regulatory Guide 1.200 Revision 1 guidance
- GAPs identified
- Applicable GAPs addressed
RI lSI
Background
- Submittal consists of the following sections
- Risk Methodology based on Code Case N 716
- Risk information included
- PRA Model Capability addressed
- Performed Internal Flooding Analysis in support of submittal
RI lSI
Background
- Reviewed Risk Model for this use in accordance with current guidance
- Determined Risk Model acceptable for use in RI lSI Applications
- Assisted by industry-recognized subject matter experts
- experience with many RI lSI submittals
- Implemented latest industry guidance
- Compared with other RI lSI submittals
- Incorporated lessons learned from RAls
River Bend Station PRA
Background
- IPE approved via Oct. '97 NRC Staff Evaluation
- Used in support of various risk-informed License Amendment Requests
River Bend Station PRA
Background
- Revision 5 update: Scheduled completion
- Dec. 2010
PRA Self-Assessment Gap Analysis
- Performed Self-Assessment cons*istent with RG 1.200 R.1 Section 4.1 in late 2008
PRA Self-Assessment Gap Analysis
- Used industry expertise in Gap analysis
- Entergy lead for Internal Flooding and Maintenance/Update elements
- Internal Flooding PRA performed to meet ASME Cat. II
PRA Self-Assessment Gap Analysis
- Gap: All items where any work required to meet RG 1.200 characterized as "gaps"
- Self-assessment grading consistent with RG 1.200 Section 2.1 expectations
PRA Self-Assessment Gap Analysis
- Gaps to RG 1.200 identified in submittal
- Consistent with RG 1.174
- Consistent with Vogtle
PRA Quality Per RG 1.174 section 2.2.6:
"There are, however, some applications that, because of the nature of the proposed change, have a limited impact on risk, and this is reflected in the impact on the elements of the risk model.
An example is risk-informed in-service inspection (RI-ISI). In this application, risk significance was used as one criterion for selecting pipe segments to be periodically examined for cracking. During the staff review it became clear that a high level of emphasis on PRA technical acceptability was not necessary.
Therefore, the staff review ofplant-specific RI-ISI typically will include only a limited scope review of PRA technical acceptability. "
PRA Quality
- N-716 RI lSI less reliant on PRA than other RI lSI approaches
- Binning before selection
- PRA one of 5 elements
- Absolute risk ranking
- N-716 criteria
- Degradation Mechanisms
PRA Self-Assessment
- Self-Assessment performed to identify all work to meet RG 1.200, including Cat. II, for other future risk-informed applications
Of the 72 Supporting Requirements (SR) with identified gaps, 7 SR's have different requirements for Cat. I vs. Cat. II.
PRA Gap Analysis
- Breakdown of gaps:
- 40 gaps: Documentation Issues
- 13 gaps: Need not be met (per EPRI) mostly uncertainty issues, would not Impact RI lSI.
- 10 gaps: Model refinements potentially needed but not significant for RI lSI
- 6 gaps (9 items): Model refinements or sensitivity studies. Addressed in Table 2 of submittal.
PRA Inputs
- Internal Flooding PRA completed June 2009
--meets Cat. II requirements
- Two cases quantified:
- Base: EPRI pipe break frequencies
- Sensitivity (Conservative, used for N-716 screening)
PRA Inputs
- Used IFPRA to assess CDF (~1 E-06) and LERF (~1 E-07) for segments considered conservative due to assumptions &
conservative simplifications due to scope
- Used PRA to confirm and provide upper limit CCDP/CLERP values in N-716 risk impact assessment
- Compared risk impact results to guidance of RG1.174
PRA Inputs
- Addressed potentially applicable gaps in Table 2 of June 16 submittal
--includes sensitivity studies
- Controlled procedurally by common Entergy process
PRA Conclusion
- Followed established process
-Cat. II Internal Flooding PRA
- Gaps to ASME Std. addressed, do not impact use for RI lSI
Q)
()
c co
+-'
c..
Q)
()
()
() co co s....
0::
Q)
-c Z
+-'
c s....
Q) 0 ()
c.
+-'
c..
c 0
en
~ -
s....
Q) co 0:::
c..
0)
E C)
~
0 I
()
()
--I
I Q) co C
I.
Q)
+-'
l.
0 I
+-'
en Q)
- J 0
Q) 0:::
- co L.
(])
+-' -
C Cf)-
"'0 c
N
\\t-O C
0 CJ) c
(])
+-'
w
lSI Interval Extension
Background
- Previously extended lSI Interval to RF-15 for examination of 123 welds.
- Projected exposure for these examinations
- 17.83 Rem
- RBS proposed to perform 73 examinations by startup from RF-15
- Requested extension of lSI interval from RF-15 until RF-16 for remaining 50 examinations
lSI Interval Extension Exposure Projections
- Include weld prep time, RP, scaffolding, insulation support and NDE
- Based upon current plant conditions, and crediting previous chemical cleaning, use of shielding and system flushing
- Validated during RWP challenge process for RF-15
lSI Interval Extension Result of Approval
- Extension results in ~90%
completion of subject Examination Categories for Second lSI Interval by end of RF-15
- NOTE: Subject examinations greatly reduced under RI lSI requirements
- 123 examinations under conventional lSI program
- 14 examinations under RI lSI program
lSI Interval Extension Examinations Result
- 43 examinations deferred to RF-16 pending RI lSI approval (not required under RI lSI)
- 80 examinations performed during RF-15
- No additional actions required when RI lSI submittal approved
lSI Interval Extension Conclusions
- Low significance for extension based on:
acceptable previous examination history
- industry experience for failure probabilities
- proposed RI lSI program indicates 43 welds would not require future examination
- Excessive radiation exposure without a compensating increase in quality or safety
- 0) u c
co
+-J 0
- 0)
U U <<
o.~
0::
Ci3 z~
s....
.so c o CJ) s....
CO 0
E o o co
\\J C
Q) 0..
0..
I 0')
o
~
()-
I
--J