ULNRC-05998, Response to Request for Additional Information License Amendment Request to Revise the Licensing Basis for Seismic Design as Described in the FSAR-SP Union Electric Company Callaway Plant, Unit 1
| ML13158A010 | |
| Person / Time | |
|---|---|
| Site: | Callaway  |
| Issue date: | 06/06/2013 |
| From: | Ameren Missouri, Union Electric Co |
| To: | Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML131580110 | List: |
| References | |
| ULNRC-05998 | |
| Download: ML13158A010 (13) | |
Text
ULNRC-05998 June 6, 2013 Page 1 of 13 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION LICENSE AMENDMENT REQUEST TO REVISE THE LICENSING BASIS FOR SEISMIC DESIGN AS DESCRIBED IN THE FSAR-SP UNION ELECTRIC COMPANY CALLAWAY PLANT, UNIT 1 DOCKET NO. 50-483
ULNRC-05998 June 6, 2013 Page 2 of 13 Mechanical and Civil Engineering Branch (EMCB)-Callaway-IHA-RAI-1 In section 2.2 (paragraph 2, page 4) of Reference 1, the licensee indicated that the weighted average damping value will be used in the analysis of loss-of-coolant accident (LOCA) loads in the Integrated Head Assembly (IHA) design basis. The licensee is requested to clarify whether the LOCA analysis performed for the IHA assembly (1) is a linear elastic analysis, (2) utilizes the response spectrum or time history method, and (3) if a response spectrum method was used, whether the type of spectra utilized is acceleration spectra or displacement spectra for the three orthogonal directions.
Callaway Response
- 1.
The LOCA analysis performed for the IHA is a linear elastic analysis.
- 2.
The LOCA analysis utilizes the response spectrum method.
- 3.
The three directional acceleration response spectra developed at the Replacement Reactor Vessel Closure Head (RRVCH) Center of Gravity (CG) by the Reactor Original Equipment Manufacturer (OEM) are used in the LOCA analysis of the IHA.
ULNRC-05998 June 6, 2013 Page 3 of 13 EMCB-Callaway-IHA-RAI-2 In section 3.1 (paragraph 2, page 6) of Reference 1, the licensee indicated that the ductwork part of the IHA structure is not composed of a traditional round or rectangular section. It is also not clear from Fig. 2 of the attachment 1 of Reference 1, what is the cross sectional shape of the Control Rod Drive Mechanism (CRDM) ductwork inside the IHA shroud. The licensee is requested to describe the cross sectional shape of the CRDM ductwork inside the IHA shroud.
Callaway Response The cross sectional shape of the CRDM ductwork is shown in the figure below which corresponds to Figure 2 of Attachment 1 of Reference 1. Please note the dimensions are in inches.
ULNRC-05998 June 6, 2013 Page 4 of 13 EMCB-Callaway-IHA-RAI-3 In section 3.1(paragraph 4, page 6) of Reference 1, the licensee indicated that there are gaps between the digital rod position indication (DPRI) plates, which transmit seismic loads from the Control Rod Drive Mechanism (CRDM) pressure housings to the seismic frame assembly. The licensee is requested to provide the following additional information: (1) How large are the gaps between the DPRI plates, (2) How are the non-linear effects of the gaps considered in the seismic analysis, (3) Is the seismic analysis of the IHA assembly a linear analysis, and (4) If it is a linear analysis, how are the impact effects accounted for during the seismic movements and closure of the gaps.
Callaway Response
- 1.
The original design of the CRDM seismic support by the Reactor OEM considered 0.07 gap (cold) between the DRPI plates. The same gap is maintained between the DRPI plates on the replacement CRDMs on the RRVCH.
- 2.
A time history analysis study of the RRVCH with the CRDMs for the Diablo Canyon Power Plant (Diablo Canyon RRVCH and the Callaway RRVCH are essentially the same size and the CRDMs are similar, all supplied by AREVA) indicated that there is a phase difference between the CRDM excitation and the IHA excitation and the maximum effect due to impact between the DRPI plates is limited to the DRPI plates only. In the linear analysis of the IHA, the DRPI plates as well as the interface between the DRPI plates and the bumper screws on the IHA seismic frame (seismic frame includes inner seismic ring beam, seismic bars, and outer seismic ring beam) are connected with linear springs and therefore, the loads on the DRPI plates and the IHA bumper disks and screws (including threaded connections) obtained from the IHA linear analysis are multiplied by a factor of 2.0 to account for the impact effect from small gaps provided between the DRPI plates. This impact between the perimeter DRPI plates and the seismic frame has only a local effect because the movement of the seismic frame is out-of-phase with the CRDMs and impact occurs when the seismic frame stresses are their lowest. When the CRDMs and IHA are in-phase, and the seismic frame stresses are their highest (which include the CRDM inertia loading) impact loading between the DRPI plates and seismic frame is insignificant.
- 3.
Yes. The seismic analysis of the IHA is a linear analysis using seismic acceleration response spectra in 3 orthogonal directions (East-West, North-South, and Vertical).
- 4.
Please see response no. 2 above.
ULNRC-05998 June 6, 2013 Page 5 of 13 EMCB-Callaway-IHA-RAI-4 In section 3.3 (paragraph 1, page 8) of Reference 1, the licensee indicated that there will be a net increase in the overall weight of the IHA assembly that is replacing the current lifting rig /
platform during the Callaway Replacement Reactor Vessel Closure Head (RRVCH) project.
The licensee is requested to provide the following: (1) the old and new overall weight of the IHA assembly, (2) clarify whether the loads due to additional mass of the IHA assembly are considered in the qualification of (i) the Reactor Vessel supports, (ii) local areas of the IHA assembly support connections with the RRVCH, and (iii) the tie rod connections to the reactor cavity wall, and (3) clarify whether the tie rods of the IHA assembly connected to the reactor cavity wall provide horizontal restraint only, or is there a vertical component.
Callaway Response
- 1.
Approximate weight of service structure supported by the original reactor vessel closure head (Operational, not including Refueling Configuration)
=
30,000 lbs.
Approximate Weight of the IHA
=
103,842 lbs.
- 2.
The loads from the IHA are considered in: (i) the R.V. Support qualification; (ii) the IHA interface locations with the RVCH (support and lift lugs); and (iii) the tie rod connections to the reactor cavity wall.
- 3.
The same concept as in the original design by the OEM is maintained in the IHA seismic tie rod design (tension only member) to transfer loads from the IHA to the cavity walls.
Tie rods are designed as tension only axial members to transfer horizontal seismic loads from the IHA to the cavity walls. However, due to slight inclined orientation of the tie rods due to two different elevations of the CRDM DRPI plates and the tie rod embedment on the cavity walls, a very small vertical load component exists at both ends of the tie rod attachments. These tie rod attachments are designed to take the vertical load components in addition to the horizontal components.
ULNRC-05998 June 6, 2013 Page 6 of 13 EMCB-Callaway-IHA-RAI-5 In section 3.3 (paragraph 2, page 8) of Reference 1, the licensee describes the finite element model and analysis of the IHA assembly based on shell and beam elements. The analysis considers the active tie rods. The licensee is requested to respond to the following questions:
(1) Was a mesh sensitivity study performed for convergence of the finite element analysis (FEA) results? (2) What structural analysis finite element program is utilized in the analysis of the IHA assembly, and was that FEA program previously qualified and listed in the Callaway FSAR and used for other components or structures at the Callaway plant, or it is an entirely new computer program? (3) What is the total number of tie rods, and how many of them are active tie rods?
(4) Are the number of active tie rods the same for the Operating Basis Earthquake (OBE) and the Safe Shutdown Earthquake (SSE) seismic analyses?
Callaway Response
- 1.
In excess of 50 iterations were performed to properly size the IHA members. All convergence issues were resolved prior to performing the final analysis. The verification of the FEA model for its accuracy was performed by reviewing the analysis results for known simple static loads (test runs) prior to performing complex analyses by experienced analysts. In addition, a third party independent review of the test runs was performed by qualified individual(s) to validate the accuracy of the FEA model.
- 2.
General purpose finite element program, ANSYS is used to perform the IHA structural analysis. The ANSYS program is qualified and listed in the Callaway FSAR and used for other components or structures at the Callaway plant. ANSYS is listed in Callaway FSAR Table 3.9(B)-1 as an acceptable computer program used at the Callaway Plant.
- 3.
For the IHA, there are total 4 seismic tie rods and all of them are active during plant operation.
- 4.
The number of active seismic tie rods is the same in both OBE and SSE analysis.
ULNRC-05998 June 6, 2013 Page 7 of 13 EMCB-Callaway-IHA-RAI-6 Section 3.3 (paragraph 3, page 8) of Reference 1 provides the OBE and SSE seismic analyses based on envelopes of the building spectra at elevation 2047-6 and the RRVCH spectra. The licensee is requested to provide (1) what the elevations are for the RRVCH spectra, and (2) whether the elevation 2047-6 corresponds to the reactor building floor spectra or the internal structure spectra.
Callaway Response
- 1.
RRVCH spectra for both OBE and SSE earthquakes are at the reactor vessel head CG location when the RRVCH is installed on the R.V. in the reactor cavity (RRVCH flange elevation = 2021-6; RRVCH CG elevation is 2025-3.6, 45.6 above the RRVCH mating surface)
- 2.
The spectra at elevation 2047-6 correspond to the reactor building internal structure.
Please note as described in the Callaway FSAR, the reactor building response spectra is the envelope response spectra for the SNUPPS* design, which included Callaway, Sterling, and Wolf Creek Plants at elevation 2047-6.
- SNUPPS - Standard Nuclear Unit Power Plant System
ULNRC-05998 June 6, 2013 Page 8 of 13 EMCB-Callaway-IHA-RAI-7 Section 3.3 (paragraph 2, page 10) of Reference 1 notes that seismic category I components of the IHA assembly were evaluated using acceptance criteria corresponding to the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel (B&PV) Code,Section III, Division I, Subsection, 2001 Edition through 2003 Addenda. Please provide clarifications to the following questions: (1) What is the design basis code for the Callaway Plant? (2) Was a code reconciliation performed for using the ASME B&PV Code,Section III for the IHA assembly versus the design basis code? (3) Was the same ASME Code edition used for the non-seismic category I components?
Callaway Response As stated in Reference 1, the Integrated Head Assembly (IHA) was designed as a replacement structure for the existing reactor vessel head service structure. The concept of integrating all the removable upper reactor vessel head components into one removable structure is the object of this design. However, functionality of each head component is maintained in the integrated head assembly. Unlike the IHA, which is attached to and supported by the replacement reactor vessel closure head, the existing reactor vessel head service structure (CRDM Ventilation and Missile Shield) is primarily supported by the refueling cavity walls and operating deck.
On the existing reactor vessel head service structure the CRDM Seismic Support consists of the Digital Rod Position Indicator (DRPI) top plates, the spacer plates, the seismic support platform, the tie rod assemblies and the lifting legs.
- 1.
For the Safety Related, Seismic Category I CRDM seismic support assembly portion of the IHA structure, the code of record for the existing equipment is the 1977 Edition with Addenda though Summer 1977 of ASME Section III, Subsection NF (Class 1). The remainder of the existing reactor vessel head service structure is not designed to the ASME B&PV Code, since it is not attached to the reactor vessel closure head nor does it perform a support function for any ASME B&PV Code components.
- 2.
The use of ASME Section III, Subsection NF, 2001 Edition with Addenda through 2003 is reconciled to the extent required by the 1998 Edition with Addenda through 2000 of ASME Section XI governing Callaways Repair / Replacement Program under which the CRDM pressure boundary seismic support assembly portion of the IHA is being replaced. In accordance with IWA-4226 of ASME Section XI, when a replacement item is designed to all requirements of a later edition/addenda of the construction code (or Section III when the Construction Code was not Section III), no reconciliation of code requirements beyond the design related issues in IWA-4224 for materials and IWA-4225 for fabrication is required. In accordance with IWA-4225, fabrication of an item to later edition/addenda of the Construction Code is acceptable provided materials are reconciled in accordance with IWA-4224 and any changes in weight, configuration,
ULNRC-05998 June 6, 2013 Page 9 of 13 pressure-temperature rating are evaluated in accordance with IWA-4311. The requirements of IWA-4311 are subsequently satisfied through the Design Report which also evaluates the actual replacement materials being used thereby satisfying IWA-4224 and therefore, all requirements of ASME Section XI with regard to use of a later code edition/addenda are considered to be met.
- 3.
Yes. For the IHA components the same ASME B&PV Code,Section III, Division I, Subsection NF, 2001 Edition through 2003 Addenda is used for both seismic and non-seismic category 1 components.
ULNRC-05998 June 6, 2013 Page 10 of 13 EMCB-Callaway-IHA-RAI-8 of Reference 1 (pages 2, 3, & 4):
The IHA assembly is a complex structure, as shown in Figures 1, 2, and 3 of Attachment 1. The licensee is requested to provide the major overall dimensions and label the major components in Figures 1, 2, and 3. Also, please provide the elevations for all of the major component locations.
Callaway Response Major overall dimensions and major component labeling are shown in the figures below, which correspond to Figures 1, 2 and 3 respectively, of Attachment 1 of Reference 1. Please note the dimensions are in inches.
ULNRC-05998 June 6, 2013 Page 11 of 13 Tripod Lift Eye Fan Cable Bridge CRDM Cooling Fans Air Plenum Top EL. 2056'-7.98" Seismic Emb PL.
NW Cable Bridge EL. 2046'-5" Seismic Seismic Support Tie Rod EL. 2047'-10.11" 42'-9.20" NW Cable Bridge IHA Upper NE Cable Bridge Shroud IHA Middle Shroud Air Inlet Air Inlet Base EL. 2034'-10.75" IHA Lower Shroud IHA Ring Beam EL. 2026'-1" Attachment to the RRVCH EL. 2021'-6" 23'-2"
ULNRC-05998 June 6, 2013 Page 12 of 13 (124.55" (typ))
124.2" 178.00" CRDM Air Duct CRDM Air Inlet CRDM Air Inlet U Bolts for Lift Rods IHA Support Columns
ULNRC-05998 June 6, 2013 Page 13 of 13 Seismic Ring Beam EL. 2047'-10.11" Seismic Emb. PL EL. 2046' - 5.00" Upper Shroud Assembly Seismic Tie Rods 23'-2" Plant North Containment Cavity 30'-1.15" CRDM Cooling NW Cable Bridge Fans Air Plenum NE Cable Bridge IHA Tripod Seismic Tie Rods Fan Cable Bridge IHA Walkway