Advisory Committee on Reactor Safeguards
Full Committee
Davis-Besse Nuclear Power Station
Final & Supplemental Safety Evaluation Report
November 4, 2015
Rick Plasse, Project Manager
Office of Nuclear Reactor Regulation
Overview
• LRA Submitted by letter dated August 27,
2010
• Pressurized Water Reactor (PWR),
Babcock & Wilcox nuclear steam supply
system
• Operating license for NPF-3 expires April
22, 2017
• Located approximately 20 miles east of
Toledo, OH
2
Safety Review Results
• Safety Evaluation Report (SER) with Open
Items was issued July 2012
• ACRS License Renewal Subcommittee
Meeting held September 19, 2012
• Final SER was issued September 2013
• Supplement to SER was issued August
2015
• ACRS 2nd License Renewal Subcommittee
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Meeting held September 23, 2015
Open Item B.1.4-1:
Closed
OI B.1.4-1 Operating Experience
• Issue: During review, LR-ISG-2011-05, “Ongoing
Review of Operating Experience,” was issued
• Basis for closure: Applicant provided additional
information that addressed the guidance in
LR-ISG-2011-05
Applicant will enhance AMPs or develop new AMPs when
necessary to ensure effects of aging are adequately
managed
4
Open Item 4.2-1:
Closed
OI 4.2-1 Reactor Vessel Neutron Embrittlement
(SER Section 4.2.2):
• Issue: Reactor vessel welds with unknown initial upper
shelf energies (USE) require an equivalent margins
analysis (EMA), per §Part 50, App G, requirements
• Basis for closure: EMA submitted and approved to
demonstrate that the welds will have adequate margins
of safety on USE, as required by §Part 50, App. G
• EMA provides an acceptable basis to accept the USE
TLAA under §54.21(c)(1)(ii).
5
Open Item 4.2.4-1:
Closed
OI 4.2.4-1 Pressure-Temperature (P-T) Limits:
• Issue: Methodology (Report BAW-10046-A, Rev. 2)
invoked by Tech. Spec. 5.6.4 for calculating P-T limits
may not assess potentially limiting reactor vessel nonbeltline locations
• Basis for closure: Applicant demonstrated Report
BAW-10046, Rev. 2, appropriately accounts for
potentially limiting reactor vessel non-beltline locations
near geometric discontinuities.
• TS basis remains valid to accept under §54.21(c)(1)(iii).
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Safety Review
Results
• Final SER issued September 2013 (all
open items were closed): 44 AMPs total
Existing New
Staff Disposition of Program
AMPs AMPs
Consistent with the GALL Report
9
5
Consistent with enhancements
11
2
Consistent with exceptions
2
Consistent with both
5
enhancements and exceptions
Plant specific
4
6
Subtotals: 31
13
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SER Supplement 1
• Supplement 1 to SER issued August 10, 2015
– Reactor Vessel Internals Inspection Plan and
Program
– Annual Updates in 2013, 2014, and 2015
– Updated information and commitments in response to
recent industry operating experience
– New plant specific program Service Level III Coating
and Linings Monitoring Program
– Steam Generator Replacement (Spring 2014)
– Shield Building Laminar Cracking Propagation
• Conclusion is unchanged
• List of Commitments in Appendix A
– Several commitments completed and
reviewed
by
NRC
staff
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Shield Building Monitoring
Program (OI 3.0.3.2.15-1)
•
Shield Building Monitoring Program to manage aging effects on
laminar cracks; preventive protective coating applied. Plant-specific
prevention & condition monitoring AMP, supplements Structures
Monitoring Program
•
Scope includes SB Wall Concrete & Reinforcing Steel; SB exterior
concrete coatings
•
Periodic visual inspections of representative sample of core holes;
Visual inspections will be supplemented with NDE (i.e., Impulse
Response (IR) Mapping)
•
Opportunistic visual inspections of rebar near laminar cracking
•
Periodic visual inspections of exterior coating every 5 years &
coating reapplied every 15 years
•
Personnel qualifications per ACI Report 349.3R Ch. 7
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Shield Building Monitoring
Program (contd…)
Operating experience of crack propagation:
• AMP considers and incorporates future operating
experience, as necessary
• Accordingly, the applicant revised AMP to incorporate
plant-specific OpE of laminar crack propagation
discovered in 2013 & 2015, attributed to “ice-wedging”
phenomenon
• Revised AMP increased inspection sample size of core
holes, increased inspection frequency, and conducts IR
to confirm extent of crack propagation
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Shield Building Monitoring
Program (contd…)
Adequacy of sample size and distribution:
• Representative sample for inspection consists of a
minimum of 28 core hole locations, with provisions for
consideration of past evidence of propagation and
expanding inspection sample.
• 14 are cracked covering the spectrum of locations with
highest prevalence of cracking and a range of observed
crack widths; includes the 3 maximum observed crack
widths, to monitor crack width & planar limit of
propagation.
• 14 are uncracked but generally located near areas of
known cracking providing ability to monitor propagation
including 5 leading edge bores to monitor limits of
recent planar propagation.
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Shield Building Monitoring
Program (contd…)
Acceptance Criteria for Core Bore Inspection Findings:
• Need for corrective action evaluated in Corrective Action
Program using evaluation hierarchy in Figure 5.1 of ACI
349.3R, if any of below criteria not met.
Qualitative: Cracking remains passive
– No discernible change in existing cracks (width, planar size)
– No Indication of new cracking in bores or from IR mapping
Quantitative: Bounded by qualitative criteria; and bounded by SB
calculations-of-record
– Crack width does not exceed 0.013 inch (current observed
maximum width)
– Extent of circumferential planar crack limit does not exceed that
in SER Table 3.0.3.3.9-2.
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ACI 349.3R Evaluation
Heirarchy
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Shield Building Monitoring
Program – Conclusion
 In summary, the staff finds the SBMP AMP acceptable
because:
• Laminar cracks are inspected at a 1 year interval and this interval
will not be progressively incremented to 2/4 years unless cracks
become passive
• A representative sample of no less than 28 core bores will be
inspected at every inspection to effectively monitor crack width and
planar limit
• The use of visual inspections and Impulse response testing can
effectively detect changes in laminar cracking
• Inspection findings will be evaluated by qualified personnel using
the evaluation procedure in ACI Report 349.3R
• The acceptance criteria of crack being “not passive” would trigger
further evaluation under the corrective action program if inspection
findings indicate discernable change in the cracks
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Shield Building Monitoring
Program – Conclusion (contd..)
 Based on the AMP attributes discussed in the previous
slides, staff concludes that through implementation of the
AMP, the applicant will be able to adequately monitor the
cracks, perform structural evaluations, and take timely
corrective actions, if necessary, prior to loss of function
 Staff thus concludes that there is reasonable assurance that
aging effects on the shield building laminar cracking will be
adequately managed by the Shield Building Monitoring
Program, such that intended functions will be maintained
during the period of extended operation.
 OI 3.0.3.2.15-1 is closed and staff evaluation is documented
in SER/SSER Section 3.0.3.3.9.
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Conclusion
On the basis of its review, the staff
determines that the requirements of
10 CFR 54.29(a) have been met for the
license renewal of Davis-Besse Nuclear
Power Station
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