ML14353A425
| ML14353A425 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 12/30/2014 |
| From: | Sayoc E License Renewal Projects Branch 1 |
| To: | Lieb R FirstEnergy Nuclear Operating Co |
| Sayoc E, NRR/DLR/RPB1, 301-415-4084 | |
| References | |
| TAC ME4640 | |
| Download: ML14353A425 (8) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 December 30, 2014 Mr. Raymond A. Lieb Vice President Davis-Besse Nuclear Power Station FirstEnergy Nuclear Operating Company 5501 North State Route 2 Oak Harbor, OH 43449
SUBJECT:
REQUEST FOR ADDITIONAL INFORMATION FOR THE REVIEW OF THE DAVIS-BESSE NUCLEAR POWER STATION LICENSE RENEWAL APPLICATION (TAC NO. ME4640)
Dear Mr. Lieb:
By letter dated August 27, 2010, FirstEnergy Nuclear Operating Company submitted an application pursuant to Title 10 of the Code of Federal Regulations Part 54 for renewal of operating license NPF-3 for the Davis-Besse Nuclear Power Station. The staff of the U.S. Nuclear Regulatory Commission (NRC or the staff) is reviewing this application in accordance with the guidance in NUREG-1800, Standard Review Plan for Review of License Renewal Applications for Nuclear Power Plants. During its review, the staff has identified areas where additional information is needed to complete the review. The staffs request for additional information is included in the enclosure. Further requests for additional information may be issued in the future.
Items in the enclosure were discussed with Cliff Custer, of your staff, and a mutually agreeable date for the response is 30 days from the date of this letter. If you have any questions, please contact me by telephone at 301-415-4084 or by e-mail at Emmanuel.Sayoc@nrc.gov.
Sincerely,
/RA/
Emmanuel Sayoc, Project Manager Projects Branch 1 Division of License Renewal Office of Nuclear Reactor Regulation Docket No. 50-346
Enclosure:
As stated cc w/encl: Listserv
- Concurred via e-mail OFFICE LA:DLR:RPB2*
PM:DLR:RPB1 BC:DLR:RPB1 PM:DLR:RPB1 NAME IBetts ESayoc YDiaz-Sanabria ESayoc DATE 12/23/14 12/30/14 12/30/14 12/30/14
SUBJECT:
REQUEST FOR ADDITIONAL INFORMATION FOR THE REVIEW OF THE DAVIS-BESSE NUCLEAR POWER STATION LICENSE RENEWAL APPLICATION (TAC NO. ME4640)
DISTRIBUTION:
HARD COPY:
DLR R/F E-MAIL:
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ENCLOSURE DAVIS-BESSE NUCLEAR POWER STATION LICENSE RENEWAL APPLICATION SUPPLEMENTAL REQUESTS FOR ADDITIONAL INFORMATION SHIELD BUILDING MONITORING PROGRAM RAI FOLLOW-UP RELATED TO 2013 PLANT-SPECIFIC OPERATING EXPERIENCE RAI B.2.43-7
Background:
License Renewal Application (LRA) Amendment No. 51 submitted by letter dated July 3, 2014, updated the plant-specific Shield Building Monitoring Program (SBMP) in LRA Section B.2.43 to incorporate the 2013 operating experience of propagation of laminar cracking in the Davis-Besse Nuclear Power Station, Unit 1 (Davis-Besse) shield building. The operating experience program element of the updated SBMP described conditions involving propagation of the shield building laminar cracks by ice-wedging identified during a 2013 base line inspection, and states in part:
[] The condition was not passive; however, it was bounded by design basis documentation. The Shield Building Monitoring Program was changed to ensure conformance with the design requirements and to maintain the [updated safety analysis report (USAR)] functions.
The Shield Building laminar cracking condition has been evaluated with respect to the design basis functions of the Shield Building. The condition is documented in [First Energy Nuclear Operating Company (FENOC)]
Calculation C-CSS-099.20-063, as supported by Bechtel Report, Effect of Laminar Cracks on Splice Capacity of No. 11 Bars based on Testing Conducted at Purdue University and University of Kansas for Davis-Besse Shield Building, that the Shield Building,... meets all design requirements specified in USAR and will perform its USAR described design functions. This analysis bounds the identified changes in the laminar cracking condition from the conditions identified in 2011.
Referencing the Evaluation criteria hierarchy of [American Concrete Institute (ACI)] 349.3R, Figure 5.1, the 2013 condition was determined to be acceptable through evaluation. The condition was not passive; however, it was bounded by design basis documentation. The condition will therefore be subjected to increased monitoring to ensure conformance with the design requirements and USAR functions.
The acceptance criteria program element of the updated SBMP, states in part:
Indications of relevant conditions of degradation detected during the inspections will be evaluated and compared to pre-determined acceptance criteria. The acceptance criteria will be defined to ensure that the need for corrective actions is identified before loss of structure or component intended functions. If the acceptance criteria are not met, then the indications or conditions will be evaluated under the FENOC Corrective Action Program.
Engineering evaluation by qualified personnel will be used for disposition of inspection findings that do not meet the acceptance criteria.
For core bore inspections, unacceptable inspection findings will include any indication of new cracking or a discernable change in previously identified cracks. Any indication of new cracking is defined as a visual inspection finding that visible cracks have developed in core bores that previously had no visible cracks. A discernable change in a previously identified crack is defined as a visual inspection finding that there has been a discernable change in general appearance or in crack width as identified by crack comparator measurement.
Conditions to be evaluated following each inspection cycle for determination of acceptable results include conformance with the plant design and licensing basis as well as with previously determined crack propagation rates.
Comparison with previously determined propagation rates will be to identify any potential changes in the driving force of the condition.
The acceptance criteria for any identified loss of material or change of material properties will be as described in Chapter 5 of ACI Report 349.3R.
The acceptance criteria element for plant-specific aging management programs (AMPs) described in NUREG-1800, Revision 2, Standard Review Plan for Review of License Renewal Applications for Nuclear Power Plants (SRP-LR), Appendix A.1, Aging Management Review -
Generic (Branch Technical Position RLSB-1) states, in part:
- 1. The quantitative or qualitative acceptance criteria of the program and its basis should be described. The acceptance criteria, against which the need for corrective actions are evaluated, should ensure that the structure-and component-intended function(s) are maintained consistent with all current licensing basis (CLB) design conditions during the period of extended operation. The program should include a methodology for analyzing the results against applicable acceptance criteria.
For example, carbon steel pipe wall thinning may occur under certain conditions due to [flow accelerated corrosion (FAC)]. An AMP for FAC may consist of periodically measuring the pipe wall thickness and comparing that to a specific minimum wall acceptance criterion. Corrective action is taken, such as piping replacement, before deadweight, seismic, and other loads, and this acceptance criterion must be appropriate to ensure that the thinned piping would be able to carry these CLB design loads. This acceptance criterion should provide for timely corrective action before loss of intended function under these CLB design loads.
- 2. Acceptance criteria could be specific numerical values, or could consist of a discussion of the process for calculating specific numerical values of conditional acceptance criteria to ensure that the structure-and component-intended function(s) will be maintained under all CLB design conditions.
Information from available references may be cited.
Issue:
The staff identified the following concerns:
The primary structural concern of the laminar cracking and its propagation with regard to the capability of the shield building to perform its intended functions is the potential loss of bond between the concrete and the rebar at the location of the laminar cracks and the ability for stress transfer to take place between the concrete and the rebar. This would be a function of the laminar crack width and length (or planar limit) along the rebar or rebar lap-splice. In this regard, it is not clear to the staff what quantitative (numerical) limits of laminar cracking characteristics [i.e., crack width, crack length (or planar limit),
number of locations, and distribution, etc.] is bounded by the design basis documentation referenced in the SBMP to determine the need for corrective actions (e.g., re-evaluation of design basis documentation, repair, etc.).
The acceptance criteria program element of the SBMP specifies that the core bore inspection findings on the concrete laminar cracking be compared and evaluated against two sets of pre-determined criteria to identify the need for corrective actions prior to loss of structure or component intended functions. These criteria include: (1) whether the laminar cracking is not passive (i.e., indications of new cracking, discernible change in previously identified cracks, or changes in previously determined crack propagation rates), and (2) whether the overall observed conditions are bounded by evaluations in the plant design and licensing basis documentation. With regard to the second case, the program does not appear to provide pre-determined quantitative acceptance criteria against which quantitative inspection findings can be compared and evaluated to determine the need for corrective actions (e.g., re-evaluation of design basis documentation, repair, etc.).
Chapter 5 of ACI 349.3R does not provide quantitative acceptance criteria applicable to concrete laminar cracking. It is not clear to the staff how the evaluation criteria hierarchy in Figure 5.1 of ACI 349.3R will be applied to the core hole inspection findings of concrete laminar cracking from the SBMP considering that only qualitative criteria related to whether laminar cracks are active or passive is available from Chapter 5 ACI 349.3R that would apply to laminar cracking.
Request:
- 1) Considering the discussion in the Issue section related to implementation of the acceptance criteria program element of the SBMP, provide additional information as below.
a) Provide information of quantitative (numerical) acceptance criteria for the shield building laminar cracking defined by bounding limits of laminar cracking characterized in terms of crack width, crack length (or planar limit), distribution, and/or any other appropriate parameters. This information may cite applicable references and should include the quantitative criteria against which the core hole inspection findings are compared and evaluated to determine (i) if the condition is bounded by and conforms to the design basis documentation referenced in the AMP (e.g., FENOC calculation C-CSS-099.20-063), and (ii) if corrective actions (e.g., re-evaluation of design basis documentation, repair, etc.) are needed to ensure that the structure and component intended functions are maintained consistent with all CLB design conditions during the period of extended operation. Update the SBMP accordingly.
Or, b) Alternatively, if the quantitative acceptance criteria for laminar cracking requested in Request (a) above is conditional, provide a sufficient discussion and basis of the process(es) for developing specific numerical values of the acceptance criteria against which the core hole inspection findings are compared and evaluated to determine (i) if the condition is bounded by and conforms to the design basis documentation referenced in the AMP (e.g., FENOC calculation C-CSS-099.20-063), and (ii) if corrective actions (e.g., re-evaluation of design basis documentation, repair, etc.) are needed to ensure that the structure and component intended functions are maintained consistent with all CLB design conditions during the period of extended operation. Update the SBMP accordingly.
- 2) Explain how the evaluation criteria hierarchy in Figure 5.1 of ACI 349.3R will be applied to the core hole inspection findings of laminar cracking from the SBMP to determine whether or not the condition is acceptable after evaluation.
RAI B.2.43-8
Background:
The applicants response to RAI B.2.43-5 (followup) by letter dated October 28, 2014 states, in part: FENOC is monitoring the crack size, shape and progression by use of 23 strategically-selected core bores, 3 of which were chosen to monitor the leading edge of crack propagation; these 23 bores is representative of the remaining cracked areas. The applicants response also includes discussion that the bore holes are examined for changes in crack width and any previously identified changes to the width will have been entered into the Corrective Action Program.
Issue:
It is not clear to the staff if the representative sample of 23 core bore holes to be inspected during the period of extended operation includes and tracks core bore holes with worst-case observed crack widths.
Request:
Clarify if core bore holes with worst-case observed laminar crack widths to-date are also included in the representative sample of 23 core bore holes that will be monitored during the period of extended operation to determine if the condition is bounded by the design basis documentation referenced in the AMP. If so, provide the number of such core holes included in the sample and the basis for this number/sample size. If not, provide a basis for their exclusion.