ML20217G605
| ML20217G605 | |
| Person / Time | |
|---|---|
| Site: | Brunswick  |
| Issue date: | 10/07/1997 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML20217G603 | List: |
| References | |
| NUDOCS 9710140057 | |
| Download: ML20217G605 (16) | |
Text
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UNITED STATES g
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NUCLEAR REGULATORY COMMISSION j'
WASHINGTON, D.C. 30HHe01 o
4*...*e SAFETYEVALUATIONBYTHEOFFICEOFNUCLEARREACTORREGULATibN RELATED TO AMENDMENT NO.189 TO FACIllTY OPERATING LICENSE NO. OPR 71 AND AMENDMENT NO.220 TO FACILITY OPERATING LICENSE NO. DPR 62 CAROLINA POWER & LIGHT COM_P. E BRUNSWICK STEAM ELECTRIC PLANT. UNITS 1 AND 2 DOCKET NOS. 50-3_25_ AND 50 324
1.0 INTRODUCTION
By "BSEP-96-0344, Application for Amends to Licenses DPR-62 & DPR-71,revising P-T Limits Curves Currently Located in Units 1 & 2 TSs & Deleting Current 8,10 & 12 Effective Full Power Yr [[Topic" contains a listed "[" character as part of the property label and has therefore been classified as invalid. Test pressure-temp Limit Curves to Add New Ones|letter dated January 7, 1997]] (Ref. 1), the Carolina Power and Light Company (CP&L or the licensee) submitted a request to amend the Technical Specifications (TS) for the Brunswick Steani Electric Plant, Unit 1 (BSEP1) and Unit 2 (BSEP2).
In the license amendment request, CP&L proposed to update the reactor pressure vessel (RPV) hydrostatic pressure test pressure temperature (P T) limit curves for the units to 14 and 16 effective full power years (EFPY).
CP&L additionally proposed exchanging two heatup/cooldown P-T curves.
TS Figures 3.4.6.1 1 (Normal Operation Core Not Critical) and 3.4.6.1-2 (Normal 0)eration Core Critical), which had been inadvertently transposed between tie BSEP1 and BSEP2 TS.
A supporting calculation Calculation Packcge CPL-420 302 (Ref. 2), performed by Structural Integrity Associates. Inc. on behalf of the licensee, was included in the amendment request.
The January 7,1997, submittal used the American Society of Mechanical Engineers Boiler and Pressure Vessel Code.
Section XI,1992 Edition, non mandatory Appendix A (ASME Auendix A)(Ref. 3) to establish the P T Limit Curves for the BSEP1 and BSEP2 PVs under hydrostatic pressure test conditions.
By letter dated June 20, 1997 (Ref. 4),
the NRC staff provided CP&L with a Request for Additional Information (RAI).
In this letter, the staff requested that CP&L provide additional infonnation to clarify the content of Ref erence 1.
The RAI informed CP&L that, pursuant to the requirements of 10 CFR 50.60, the staff could not process the license amendment request without submittal of an exemption request for a) proval to-use the methodology of ASME Appendix A as an alternative to the NRC-approved methodology found i AppendixG)(Ref.5)pAppendixGtothe1989EditionoftheASMECode(ASMECP&L p on July 25, 1997 (Ref. 6), and formally submitted the exemption request on 1
Henceforth, Appendix G to the 1989 Edition of Section XI of the ASME Code will be referred to as ASME A To avoid confusion, Appendix G to Part 50 of Title 10.ppendix G.U.S. Code of federal Regulation-be referred to as 10 CFR Part 50, A)pendix G.
Henceforth, Appendix A to the 1992 Editior, of Section XI of tie ASME Code will be referred to as ASME Appendix A.
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August 15,1997 (Ref. 7). CP&L supplemented this information with an additional administrative change to the P-T limit curve figures in its submittal to the staff dated August 27.1997 (Ref. 8). At the staff"s i
request, on September 15. 1997. CP&L provided its evaluation of a January 17.
~1992, cooldown event that occurred on BSEP1 during which P T limits were exceeded (Ref. 9),
b Further NRC staff review of Reference 7 and Appendix G to 10 CFR Part 50 L
determined that issuance of the exemption proposed by the licensee is not necessary.
I The information 15,1997.provided in CP&L's letters of June 20. 1997, July 25, 1997, q
i August August 27, 1997, and September 15,1997, does not affect the F
conclusions stated in the notice of
- Proposed No Significant Hazards 1
Consideration-Determination" published in the Federal Reaister on March 12.
1997 (62 FR 14485).
1 TS 3/4.4.6 for BSEP1 and BSEP2 provides the limiting conditions for operation 1
-(LCO) and surveillance requirements (SR) for the RPVs.
TS LC0 3.4.6.1 l
requires that the reactor coolant system (RCS) temperature and pressure be-i limited to the following conditions:
i (a)
As shown in TS Figure 3.4.6.1 1 during heat up by non nuclear means, cooldown following a nuclear shutdown, or low power physics testing; i
(b)
As shown in TS Figure 3.4.6.1 2 for operations with a critical core 1
other than low power physics tests or when the reactor vessel is j
vented:-and L
(c)
As shown in TS Figure 3.4.6.1 3a. 3.4.6.1-3b. or 3.4.6.1 3c, as j
app'licable, for inservice hydrostatic or leak rate testing:
In Reference 1. CP&L pro)osed that the folle changes be approved to TS i
3/4.4.6 for BSEP1 and BSEP2:
-(a)
Exchange TS Figures 3.4.6.1-1 and 3.4.6.1-2 between the BSEP1 and i
.BSEP2 TS:
L i-(b)
Delete the current Figures (Figures 3.4.6.1-3a. 3.4.6.1 3b and 3,4.6.1-3c) for the 8. 10, and 12 EFPY hydrostatic test P T limit curves and incorporate new 14 and 16 EFPY hydrostatic test P-T limit curves--for the BSEP1 and BSEP2 (proposed' Figures 3.4.6.13a and 3.4.6.1 3b, respectively): and
- (c)
Reformat the TS Figures 3.4.6.1-1, 3.4.6.1 2, 3.4.6.1 3a, and j-3.4.6.1-3b with administrative changes, t
p These changes include appropriate changes to TS LC0 3.4.6.1, SR 4.4.6.1.3, and.
to the TS Bases.
The staff has completed its evaluation of CP&L's submittals.
4
- The staff's evaluation is provided in Section 2.0 to this Safety Evaluation (SE).
.- ~
l 3
2.0 OfSCUSSION AND FVAl0ATION 2.1 Exchange of Figure 3.4.6.11 of the BSEP1 TS with Figure 3.4.6.11 of j
I the BSEP2 TS/Exchan e of Figure 3.4.6.12 of the BSEP1 TS with Figure 3.4.6.12 of the BS P2 TS in Licensee Event Report (LER) 1 94 05 (Ref. 10) CP&L reported the discovery of an inadvertent transposition of the heatup cooldown P T limit curves for the BSEP1 RPV (Figures 3.4.6.1 1 and Figures 3.4.6.1 2) with the corresponding figures for the BSEP2 RPV.
In-this LER, CP&L reported that this condition had resulted in the )otential use of 16ss conservative P-T limit curves for BSEP1 during previous'leatup and cooldown evolutions.
Supplemental submittals-to LER 1-94 05. which were submitted to NRC on April 29, 1994 (Ref. 11), and on
'i September 15,1994 (Ref.12), confirmed that the P-T limit curves were transposed and provided detailed information regarding the circumstances which led to the error 4 Details of the circumstances leading to the transposition i
of the P T limit curves are also summarized in Reference 1.
The staff reviewed and compared BSEP1 TS Figure 3.4.6.1 1 to BSEP2 TS Figure 3.4.6.1-1, and BSEP1 TS Figure 3.4.6.1-2 to BSEP2 TS Figure 3.4.6.1 2. The BSEP1andBSEP2heatub/cooldowncurvesvarybyasmuchas20*Fforanygiven l:
reactor pressure or I 0 psig for an
-limits in the current curves for BSfPhiven reactor temperature, with the P T being more conservative relative to the l
curves for BSEPl.
10 CFR~Part 50. Appendix G. requires that the P-T limits for operating nuclear plants be at least as conservative as those that would be obtained by ap)1ying
~
the methods of ASME Appendix G.
In this case, the transposition of the )-T limit curves results in the 30tential for heatups cooldowns. or hydrostatic or leak rate tests of the BSEP1 reactor to be non conservative with respect to what-the actual P-T limits are for the unit.
The proposed TS change will correct the non conformance with respect to the P T limit curves, and is therefore acceptable to the staff.
It should be noted that in Reference 11 l
CP&L stated that a final safety evaluation would be performed to assess the safety significance of transposing the P T limit curves after a review of all
. relevant plant operating data was completed.
I 2.2 New P T Limit Curves Operating During Hydrostatic Testing Conditions 2.2.1 Methodologies Used for Generating the P-T Limit Data and Curves for the Beltline Materials Bottom Vessel Head, and No. N16 A/B Instrument Nozzles In Reference 1. CP&L provided new P T limit curves for hydrostatic testing conditions effective to 14 EFPY and 16 EFPY (TS Figurc 3.4.6.1 3a and Figure 3.4.6.1-3b. respectively). The new curves were based on an analysis that was performed by Structural Integrity Associates. Inc. (SIA). the company contracted by CP&L to generate the new curves.
CP&L included SIA Calculation No.: CPL-420 302 in Reference 1 to support its basis for establishing the new curves.
SIA and the NRC staff both applied the methodology of Regulatory Guide 1.99. Revision 2 (Ref. 13), for the calculations of the Adjusted Reference Temperatures (ARTS) for the materials used to fabricate the beltline l-
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4 region, bottom vessel head, and No. N16 A/B instrument nozzles.
As a result of its review. the staff noted that SIA had applied a generic initiql RT,f value of 56'T to the beltline welds instead of the plant-specific value o 10'F that was provided in CP&L's November 16. 1995. response to NRC Generic letter 92 01. Revision 1, Supplement 1, ' Reactor Pressure Vessel Integrity" (Ref. 14).
However, the staff determined that even if the plant-specific value of 10*F were used in the calculations of the ARTS for the welds, the No.
N16 A/B instrument nozzles still have the most limiting ART of all the materials in both the BSEP1 and BSEP2 RPVs.
Therefore, use of a generic initial-RTa value for the weld materials did not affect the results of SIA's P-T limit assessments-for the vessels.
SIA's P T limit data for the beltline and bottom vessel head materials were based upon calculations that applied the methodology of ASME Appendix A.
For evaluations of the No. N16-A/B instrument nozzles, SIA applied finite element model methods to relate the material stress intensity for the nozzles to the reactor system pressure.
The staff determined that these finite element modeling methods were consistent with the finite element modeling methods of a May 1991 General Electric Company Topical Report NEDC 30634, Revision 1.
- Brunswick Steam Electric Plant. Unit 1. Feedwater Nozzle Fracture Mechanics Analysis" (Ref. 15), and with the finite element methods cited in Table 6 1 of Altran Corporation Technical Report No. 96124 TR-01, Revision 0, "N 16 Nozzles Upper Shelf Energy Evaluation." December 1996 (Ref.16). which was submitted in conjunction with CP&L's Equivalent Margins Analysis for the nozzles, dated April 14, 1997 (Ref. 17).
Appendix A to this SE provides a more detailed summary of SIA's methodology for establishing the new P.T limit curves for hydrostatic testing conditions.
It should be noted that, pursuant to 10 CFR Part 50, Appendix G, the P-T limits and minimum temperatures established for RPVs must meet the requirements for these parameters set forth in Table 3 of the rule. Table 3 of the rule _ incorporates the P.T limit and minimum temperature requirements set forth in 1989 Edition of ASME Appendix G.
Table 2.2.1-1 below sununarizes the minimum temperature requirements and P T limit requirements for hydrostatic and leak-rate testing conditions.
Table 2.2.1-1 Hydrostatic and Leak Rate Testing Conditions System Pressure as a Requirements Minimum Condition Percent of the Pre-for P T Temperature Service Hydrostatic Limits Requirements Pressure Fuel in the s 20%
-ASME App. G Adjust. Reference Vessel Limits Temp. (ART) of the limiting flange material Fuel in the
> 20%
ASME App. G ART of the limiting Vessel Limits flange material +
90*F
6 To meet the applicable requirements listed in Table 3 of 10 CFR Part 50, Appendix G. Paragraph 2.b. of 10 CFR Part 50. Appendix G. requires that P T limits for o)erating nuclear plants must be at least as conservative as those which would )e obtained by following the methods of analysis and the safety margins found in ASME Appendix G.
The staff performed an independent analysis using the methods described in ASME Appendix G in order to determine whether SlA's methods of determining the minimum allowable RCS pressures during hydrostatic testing conditions were conservative relative to the pressures which would have been obtained if the i
methods in ASME Appendix G were used.
For the staff's evaluations of the i
beltline and bottom vessel head materials, the staff a of the NRC's Standard Review Plan Chapter 5.3.2 (Ref. pplied the methodology 18), which is consistent with-the methodology found in ASME Appendix G.
Appendix B to this SE provides a more detailed summary of the staff s methodology for verifying the new P T limit curves for hydrostatic testing conditions for the beltlire and bottom vessel head mater 1als.
For the staff's evaluations of the No. N16 A/B instrument nozzles, the staff used the methods described in Appendix 5 of Welding Research Council (WRC) Bulletin 175 (Ref. 19).
These methods are invoked by ASME Appendix G as being acceptable methods for evaluating the inside corner of a nozzle for elastic stresses due to internal pressure.
Appendu. C to this SE provides a more detailed summary of the staff's methodology for verifying the P-T limit data and curves for the No. N16 A/B instrument nozzles.
2.2.2 Staff Evaluation of the Portions of the New P.T Limit Curves for Hydrostatic Testing Conditions Which Correspond to Pressures Less Than or Equal to 20% of the Preservice Hydrostatic Pressure (1563 psig)
For hydrostatic tests. Table 3 of 10 CFR Part 50. Appendix G recuires that for RCS pressures less than or equal to 20% of the preservice c rostatic pressure, the temperature of the system must be at least as hi cs the ART of the limiting material in the RPV closure flange, and that the
-T limits must be at least as conservative as those which would be obtained by using the methods of ASME Appendix G.
At BSEP1 and BSEP2 the preservice hydrostatic testing pressure 1s--1563 psig.
The corresponding RCS aressure range for RCS pressures less than or equal to 20% of the preservice lydrostatic pressure is O psig to 313 psig. At this pressure range the minimum tem)erature requirement is conservative with res)ect to (higher than) tie minimum temperatures which would be establisled by the P-T limit calculation requirements, and therefore is the criterion thdt normally establishes this portion of the curve.
The ARTS of the most limiting materials in the RPV closure flange at BSEP1 and BSEP2 are 16'F and 10'F. respectively.
Thus, for RCS pressures in the range of 0 psig to 313 psig, the minimum temperature of the RCS must be at least 16'F for BSEP1 and 10 F for BSEP2. CPal. has set the minimum RCS temperature for this pressure range to 70'F. This is conservative with respect to the requirements of 10 CFR Part 50. Appendix G. and therefore is acceptable to the staff.
6 2.2.3 Staff Evaluation of the Portions of the New P T Limit Curves for Hydrostatic Testing Conditions Which Correspond to Pressures Greater Than 20% of the Preservice Hydrostatic Pressure (1563 psig) for hydrostatic tests. 10 CFR Part 50. Appendix G requires that for RCS pressures greater than 20% of the preservice hydrostatic pressure (i.e. > 313 asig for BSEP1 and BSEP2), the minimum RCS temperature must be at least as ligh as the sum of the ART of the limiting material in the RPV closure flange l
and 90*F (ART + 90'F), and that the minimum tem >eratures established by P T limits must be at least conservative as those w11ch would be obtained by using the methods of ASME Appendix G.
Thus to establish a hydrostatic testing P T limit curve for pressures greater than 20% of the preservice hydrostatic pressure, the licensee must select the most conservative temperatures established by the criteria of 10 CFR Part 50. Appendix G.
This is done by su3erimposing the minimum temperature requirement (e.g., 106'F for BSEP1 and 10 PF for BSEP2) over the most limiting generated P T limit curves for the units, and selecting the most conservative P T data to establish the limiting composite P-T limit curve.
The staff has determined that, for the evaluation of the limiting materials in the BSEP1 beltline region and bottom vessel head, the methodology of ASME A)pendix A provided P-T limit curves that were at least as conservative as tiose which would have resulted if the methodology of ASME Appendix G were used to establish the curves, in assessing the new hydrostatic testing F limit curves for BSEP-1 effective to 14 EFPY and 16 EFPY, the staff determined that the P-T limit data generated from the evaluation of the No. N16-A/B instrument nozzles were always conservative relative to the P T limit data generatedfrompheevaluationsofthelimitingmaterialsinthereactorvessel beltline region and the bottom vessel head.
Thus, for BSEPl. the portions of the hydrostatic testing P T limit curves generated for 3ressures greater than 313 psig are a composite generated by superimposing tie minimum temperature requirement (106'F) oer *;he curve generated from plotting the data from the evaluations of the No. N16 A/B instrument nozzles.
In this case the kink in the curve for the 14 EFPY curve occurs at a temperature of 106'F (which complies with the minimum tem)erature requirement) and a pressure of 607 psig: at temperatures above 106' the P T data were generated from SIA's stress intensity calculations of the No. N16 A/B instrument nozzles.
The corresponding kink for the 16 EFPY curve occurs at a temperature of 106'F and a pressure of 596 psig.
The hydrostatic testing P T limit curves generated by SIA from the evaluations of the N16 A/B instrument nozzles at BSEP-1 were slightly more conservative than the corresponding curves that were generated by the staff using the methodology of ASME Appendix G.
CP&L has established i
l l
2 It should be noted that in order to generate the data for the limiting i
beltline materials for BSEP1 and BSEP2 at 14 EFPY and at 16 EFPY, SIA set the ART for the beltline to the corresponding ART value of the No. N16.A/B instrument nozzles using the 16 EFPY fluence, as the forging materials for the nozzles were determined to have the highest ART's of all materials in the beltline region.
The staff has determined that this is a valid engineering practice and provides an added conservatism in SIA's P-T limits evaluation of the BSEP1 and BSEP2 reactor pressure vessels.
r
7 the hydrostatic test P T limit curves for BSEP1 (proposed TS Figures 3.4.6.1-3a and 3.4.6.1 3b effective to 14 EFPY and 16 EFPf respectively) from the data generated by SIA from its evaluation of the No. N16 A/B instruments nozzles.
Since this is the conservative practice, the staff concludes that the hydrostatic testing curves for BSEP1 effective to 14 EFPY and to 16 EFPY are acceptable for use.
For the review of the new hydrostatic testing P-T limit curves for BSEP2, the staff determined that 51A's use of the methodology of ASME Appendix A for i
I evaluating the limiting materials in the reactor vessel beltline region and in the bottom vessel head also provided results that were at least as l
conservative as those which would have resulted if the methodology of aSHE Appendix G were used.
In assessing the new hydrostatic testing P T limit curves for BSEP2 effective to 14 EFPY and 16 EFPY, the staff determined that the P T limit data generated from the evaluation of the BSEP,. bottom head were conservative relative to the data generated from the evaluations pf the No.
N16 A/B instrument nozzles or the reactor vessel beltline region.
The kink inthecurveforthe14EFPYhgdrostatictestingP-TlimitcurveforBSEP2 occurs at a temperature of 100 F (which complies with the minimum temperature requirement) and a pressure of 542 psig: at temperatures above 100*F the minimum pressures were generated from the data generated from SlA's stress intensity calculations of the bottom vessel head.
For BSEP2, the hydrostatic test P-T limit curve effective to 16 EFPY is equivalent to the corresponding curve for 14 EFPY, as the stress intensities for the bottom vessel head are not dependent upon radiation effects.
CP&L established the hydrostatic testing P-T limit curves for BSEP2 effective to 14 EFPY and 16 EFPY from the data generated by SIA from its evaluation of the BSEP2 bottom head. Since this is the conservative practice, the staff concludes that the hydrostatic test P T limit curves for BSEP 2 effective to 14 EFPY and to 16 EFPY are acceptable for use, 2.3 Reformatting of TS Figures 3.4,6.1 1, 3.4.6.1-2, 3.4.6.1-3a, and 3.4.6.1-3b.
CP&L has not pro)osed technical changes of the current " core not critical" and
" core critical" leatup/cooldown curves for the BSEP1 and BSEP2 RPVs (Fi 3.4.6.1-1 and 3.4.6.1 2 in both the BSEP1 and BSEP2 TS, respectively), guresCP&L has proposed reformatting TS Figures 3.4.6.11,3.4.6.1-2,3.4.6.1Da,and 3.4.6.1-3b. The formatting changes include minor changes to the axes labels and removal of the references in the curves to the limiting RCS components for which the curves were established.
CP&L's proposed changes, as amended by Reference 8, constitute simple administrative changes to the existing curves, and will not affect the margins of safety established in the proposed curves nor CP&L's ability to operate BSEP1 and BSEP2 within the confines of the P T 3
It should be noted that the ART for No. N16 A/B instrument nozzles is the determining factor for the establishment of the BSEP1 hydrostatic P.
T limit curves whereas the ART for the BSEP 2 bottom head is the determining factor for establishment of the BSEP2 hydrostatic test P-T limit curves.
This difference explains how the curves were established.
I 8
limit curves during normal or transient operating conditions.
These changes are therefore acceptable to the staff.
2.4 Results of Staff Review The staff has reviewed CP&L's bases for exchanging the respective existing heatup/cooldown curves (TS Figures 3.4.6.1 1 and 3.4.6.1-2) for BSEP1 with those of BSEP2, and determined that the proposed exchange will administratively correct the error that was previously reported in Reference
- 10. This is acceptable to the staff.
The st?ff has also completed its review of the information provided by CP&L in References 1, 6, 8, and 9 in support of the TS amendment request and in Reference 7 regarding the proposed exemption. The staff has compared the licensee's new hydrostatic test P T limit curves for BSEP1 and BSEP2, which were based on the methodology of ASME Ap>endix A with staff generated curves that were based on the methodology of ASiE Appendix G. The staff has determined that use of ASME Appendix A results in hydrostatic testing P T limit curves that are at least as conservative as those that would be generated by applying the methodology of ASME A)
Thus, in accordance with Section IV. A.2.b of Appendix G to 10 CFR 5)pendix G., the exemption pro Reference 7_is not necessary. Given the staff's technical analysis, the staff concludes that, in this case, the P-T limit curves for hydrostatic testing conditions, as based on the methodology of ASME Appendix A. are therefore acceptable for use. These curves satisfy the conservatism and margin of safety requirements of 10 CFR Part 50 Appendix G.Section IV.A.2.b. regarding P T limit curves for operating lightwater nuclear reactors, and are acceptable to the staff.
The staff has also determined that the proposed administrative and corrective changes to TS 3.4.6.1 and the associated TS Bases are also acceptable.
3,0 STATE CONSULTATION In accordance with the Commission's regulations, the State of North Carolina official was notified of the proposed issuance of the amendments.
The State official had no comments.
4,0 ENVIRONMENTAL CONSIDERATION These amendments involve a change in the installation or use of a facility component located within the restricted area, as defined in 10 CFR Part 20.
The NRC' staff has determined that the amendments involve no significant increase in the amounts, and no significant change in the types, of effluents that-may be released offsite, and that there is no signifit increase in individual or-cumulative occupational radiation exposure. lne Commission has previously issued a proposed finding that the amendments involve no-significant hazards consideration, and there has been no public
-comment on such finding (62 FR 114B5). Accordingly, the amendments meet the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9).
Pursuant to 10 CFR 51.22(b) no environmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendments.
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5.0 CONCLUsfoy The Comission has concluded, based on the considerations discussed'above, that (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner. (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendments will not be inimical to the common defense and security or to the health and safety of the public.
Principal Contributor:
J. Hedoff Date:
October 7,1997 REFERENCES 1.
W.R. Cam > bell. Carolina Power and Light Company letter to the U.S.
Nuclear Regulatory Commission. January 7. 1997.
2.
Structural Integrity Associates. " Brunswick Units 1 and 2 Hydro Test P-T Curve Development." Calculation Package - File No. CPL-420 302.
Revision 1. August 22. 1996.
3.
American Society of Mechanical Engineers. Bofler and Pressure Vessel Code 1992 Edition.Section XI. Non Mandatory Appendix A.
4.
D.C. Trimble. U.S. Nuclear Regulatory Commission, letter to C.S.
Hinnant. Carolina Power & Light Company. June 20. 1997.
i 5.
American Society of Mechanical Engineers. Boiler and Pressure vessel l
Code. 1989 Edition.Section XI. Appendix G. " Fracture Toughness Criteria for Protection Against Failure."
6.
C.S. Hinnant. Carolina Power and Light Company, letter to the U.S.
Nuclear Regulatory Commission. July 25. 1997.
7.
C.S. Hinnant. Carolina Power and Light Company, letter to the U.S.
Nuclear Regulatory Comtssion. August 15. 1997.
8.
C.S. Hinnant Carolina Power and Light Company, letter to the U.S.
Nuclear Regulatory Commission. August 27, 1997.
9.
C.S. Hinnant. Carolina Power and Light Company, letter to the U.S.
Nuclear Regulatory Comission. September 15, 1997.
10.
J. Cowan. Carolina Power and Light Company. letter to the U.S.
Nuclear Regulatory Comission. March 22. 1994, forwarding Licensee Event Report No. 1-94-005.
11.
J. Cowan. Carolina Power and Li ht Company, letter to the U.S.
Nuclear Regulatory Com'.iission, ril 29, 1994, forwarding Supplement 1 to Licensee Event Report No. 1 94 005.
10 12.
J. Cowan Carolina Power and Light Company. letter to the Ll.S.
i Nuclear Regulatory Commission. September 15. 1994, forwarding Supplement 2 to Licensee Event Report No. 1 94 005.
13.
U.S. Nuclear Regulatory Comission. " Radiation Embrittlement of Reactor Vessel Materials." Regulatory Guide 1.99. Revision 2. Hay 1988.
I 14.
W.R. Cam> bell. Carolina Power and Light Company letter to the U.S-Nuclear Regulatory Commission. November 16, 1995..
l 15.
General Electric Company Pro)rietary Topical Report NEDC 30634.
Revision 1. " Brunswick Steam Electric Plant. Unit 1. Feedwater Nozzle Fracture Mechanics Analysis," May 1991.
16.
Altran Cceporation. Technicai Report No. 96124-TR 01. Revision 0.
"N-16 Nozzles Upper Shelf Energy Evaluation." December 1996.
i 17.
W. R.- Campbell. Carolina Power and Light Company, letter to the U.S.
i Nuclear Regulatory Commission. " Supplemental Information for Generic Letter 92 01. Reactor Vessel Structural Integrity,"- April 14. 1997.
18.
U.S. Nuclear Regulatory Comission. Standard Review Plan. Section 5.3.2 " Pressure Temperature Limits." NUREG 0800. Revision 1. July 1981.
19.
Welding Research Council Bulletin 175. "PVRC Recommendations on
- Toughness Requirement for Ferritic Materials." Appendix 5. "K Calculation Method for the Nozzle." August 1972 20.
0.C. Trimble. U.S Nuclear Regulatory Commission, letter to C.S.
Hinnant. Carolina Power & Ligfit Company. October 1997.
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APPENDIX A METHODOLOGY USED BY STRUCTURAL INTEGRITY ASSOCIATES. INC.
FOR CALCULATING AND ESTABLISHING THE P T LIMIT CURVES ' !
FOR THE BSEP1 AND BSEP2 REACTOR VESSELS UNDER HYDROSTATIC TESTING CONDITIONS EFFECTIVE TO 14 AND 16 EFPY l
I
- 1. P T limit curves were generated for each of the following three reactor pressure vessel (RPV) regions:
(1) beltline, which is potentially limiting due to irradiation effects on the shell forg g and weld materials. (2) 2-i inch instrument nozzles, which are effects and high stresses, and (3) potential limiting due to irradiation the bett head region, which is potentially limiting from discontinuity stresses.
2.-The methodology for establishing the curves uses the following approach:-
- a. Assume a temperature. T (*F).
f
- b. Calculate the Adjusted Reference Temperature (ART)- for the limiting l
materials in the beltline region, the bottom vessel head, and the No.
N16 A/B instrument nozzles using the methodology of Regulatory Guide 1.99. Revision 2 (1988). " Radiation Embrittlement of Reactor vessel Materials."
- c. Calculate the critical stress intensity factor K IR for the limiting materials in the beltline region, the bottom vessel head. and the No, t
N16 A/B instrument nozzles using the following equation:
l Ka - ( 1.223
- e'[0.0145 * (T - ART + 160)] ) + 26.78 (A 1)-
where T is the assumed system temperature ('F). ART is the adjusted reference temperature ('F) f r-the material, and K stress intensity factor (ksi inch) for the materiak, is the critical
- d. Calculate the critical stress intensity. K. using the following i
i equation:
K - K n/1.5 (A 2) i i
where Kr. is the critical stress intensity factor (ksilinch) for the i
material. and where the factor 1.5 is consistent with the safety factor required by 10 CFR Part 50. Appendix G. and ASME Appendix G for hydrostatic testing conditions.
.e. Compute the minimum allowable system pressure for the assumed reactor-
. coolant temperature bdsed on-the following equations:
(1)
For beltline materials and the materials in the reactor vessel bottom head using P = ( 1113.7
- K
- t ) / [ F
- R * ( (1.0936
- t) + (0.212 * ( K / o i
i
)^2)^0.5) ]
fA3)
o s a 2
where P is the reactor pressure (psig), t is the vessel thickness (inches). F is the stress intensity proportionality factor (1.0 for the beltline materials and 1.5 for the materials in the vessel bottom heau) R is the vesse' inner radius. K is the material i
stress intensity fact yieldstrength(ksi)pr(ksi, inch),anda,,isthevesselmaterial (2)
For the No.16 A/B instrument nozzles using P - 21.53
- K (A 4) i where P is the reacto pressyre (psig). K is the material stress i
intensity factor (ksi i ch)
- f. Repeat steps a, through e. using other assumed temperatures for the limiting materials in the beltline region, the bottom vessel head, and the No. N 16A/B instrument nozzles to generate P-T Limit data for the materials, and subsequently establish the P.T limit curve for hydrostatic testing using the most conservative data from the evaluations of these materials.
f 4
By letter dated June 20. 1997, the NRC staf f requested that CP&L provide the basis for using the pressure stress intensity relationship equation listed above (Equation A 3) for the beltline and l'ottom vessel head materials, CP&L provided the basis for this equation in CP&L's letti-to the staff dated July 25. 1997.
The staff has determined that couation A 3 is consistent witn the methodology provided in non-mandatory ASME Ap)endix A.
CP&L submitted an exemption request to use this methodology Jy letter dated August 15. 1997.
5 By letter dated June 20, 1997, the NRC staff requested that CP&L provide the basis for using the pressuro stress Intensity relationship equation listed above (Equation A 4) for the No. N16 A/B Instrument Nozzles.
CP&L provided the basis for this equation in CP&L's letter to the staff dated July 25, 1997.
The s M ff has determined that equation A 4 13 consistent with the stress intensity equation listed in Table 61 of P.'oprietary Altran Corporation Technical Resort No.
95124-TR 01.
Revision 0, and with Proprietary GE Report 4EDC-30634, Rev.1.
~ Brunswick Steam Electric Plant. Unit 1. Feedwater Nozzle Fracture Mechanics Analysis." dated May 1991. The Altran Re with CP&L's Equivalent Margins Analysis for the No. port was submitted N16 A/B Instrument Nozzles dated April 14, 1997.
This methodology is based on finite element modeling of the N16-A/b Instr ument Nozzles.
o<<
e APPENDIX B METHODOLOGY OSED BY THE NRC STAFF FOR VERIFYING THE P T LlHIT DATA AND CURVES FOR THE LlHITING MATERIALS IN THE BSEP1 AND BSEP2 BELTLINE REGIONS AND B0170H VESSEL HEADS UNDER HYDROSTATIC TESTING CONDITIONS EFFECTIVE TO 14 AND 16 EFPY
- 1. P T limit curves were generated for each of the following three regions:
]-
(1) beltline, which is potentially limiting due to irradiation effects on the shell forgino and weld materials. (2) 2 inch instrument nozzles, which are potentially limiting due to irradiation effects and high stresses, and (3) the bottom head region, which is potentially limiting from discontinuity stresses.
l
- 2. The methodology for verifying the P T limit data and curves uses the following approach:
j
- a. Assume a temperature. T ('F).-
b,CalculatetheAdjustedReferenceTemperature(ART)forthelimiting i
materials in the beltline region and the bottom vessel head using the methodology of Regulatory Guide 1.99. Revision 2 (1988), " Radiation j
Embrittlement of Reactor Vessel Materials."
- c. Calculate the critical stress intensity factor, Ka, for the limiting materials in the beltline regiori and the bottom vessel head, using the j
following equation:
Ka = ( 1.223
- e'[0.0145 * (T - ART + 160)] ) + 26.78 (B 1) where T is the assumed system temperature ('F). ART is the adjusted l
reference temperature (*F) for the material, and K stressintensityfactor(ksidinch)forthemateriai,,isthecritical
- d. Calculate the critical stress intensity, K, using the following 3
equation:
K - Ka/1.5 (B 2) i where K, is the critical stress intensity factor (ksidinch) for the materiai,andwherethefactor1.5isconsistentwiththesafetyfactor required by 10 CFR Part 50, Appendix G, and ASME Appendix G for hydrostatic testing conditions,
- e. Calculate the membrane stress using the following equation:
K = G
- o,
- M, (B 3) i wSere K is the material stress intensity factor, G represents a proportkonalityfactortoaccountforincreasesinthestressintensity
o c.
o 2
factor due to geometric constraints', o is the membrane stress (ksi) for the material in beltline region orlottom vessel head, anQ N is a 3roportionality factor defined in the Paragraph G;2214 of the 1989 Edition of the ASME Code,Section XI, Appendix G.
- f. Calculate the minimum allowable pressure using one of the following membrane stress equations:
(1) for evaluations of the beltline region of the reactor pressure vessels, using:
P - 1000 * (o,
- t) / R (B 4) where P is the calculated reactor pressure (psi), o, bottom vessel is the membrane stress (ksi) for the material in beltline region or head, t is the vessel shell thickness (1nches), and r is the reactor vessel inner radies (inches),
(2) for evaluations of the bottom vessel heads, using:
P - 1000 * (0,
- t) / ( 2
- R)
(B 5)
- 9. Repeat steps a. through f, using other assumed temperatures to generate the P T limit data for the beltline region and the bottom vessel head, and subsequently establish the composite P T limit curve for hydrostatic testing using the most conservative data from the evaluations of the limit materials in the beltline region, bottom vessel head, and No. N16-A/B instrument nozzles (Note:
the methodolo of the nozzles is summarized in Appendix C),gy for the staff's analysis h, Com>are the NRC generated composite hydrostatic test P T limit curve wit 1 the corresponding r T limit curve presented in the proposed Technical Specifications, 6
For plates and weld materials in the beltline region G was set equal to 1.0: for the materials in the bottom vessel head, G was set to a factor of 3.0 to account for increases in the stress intensity factor due to the presence of control rod drive mechanism (CRDM) penetration nozzles or other instrument nozzles.
These factors are consistent with the factors ured in the analysis by SIA, and with the georaetric factors reconnended in WRC Bulletin 175 1972.
7 According the Paragraph G 2214.1 of the 1989 Edition of the ASME Code,Section XI Appendix G. "The K, corresponding to membrane tension for the )ostulated defect
.., is K, - M.
- membrane stress, where M, is 1
as slown in Figure G 2214 1."
APPENDIX C METHODOLOGY USED BY THE NRC-STAFF 1
FOR VERIFYING THE P T LIMIT DATA AND CURVES FOR THE LIMITING MATERIALS IN THE BSEP1 AND BSEP2 NO. N16 A/B INSYRUMENT N0ZZLES UNDER HYDROSTATIC TESTING CONDITIONS EFFECTIVE TO 14 AND 16 EFPY
- 1. P T limit curves were generated for each of the following three regions:
(1) beltline, which is potentially limiting due to irradiation effects on the shell forging and weld materials, (2) 2 inch instrument nozzles. which are potentially lintting due to irradiation effects and high stresses, and (3) the bottom head region, which is potentially limiting from discontinuity stresses.
- 2. The methodology for verifying the P T limit data and curves for the No, l
N16 A/B instrument nozzles uses the following approach:
- a. Assume a temperature. T ('F).
I b.CalculatetheAdjustedReferenceTemperature(ART)forthelimiting materials in the No. N16 A/B instrument nozzles using the methodology of Regulatory Guide 1.99. Revision 2 (1988)
" Radiation Embrittlement of Reactor Vessel Materials."
- c. Calculate the critical stress intensity factor, Ka, for the No. N16 A/B instrument nozzles using the following equation:
Kn - ( 1.223
- e'[0.0145 * (T ART + 160)] ) + 26.78 (C 1) whereTistheassumedsystemtemperature(*F),ARTistheadjusted reference temperature ('F) for-the material, and Kg is the critical i
stressintensityfactor(ksidinch)forthemateriai.
l
- d. Calculate the critical stress intensity. K, using the following i
j
. equation:
K = Ka/1.5 (C-2) i whereK,isthecriticalstressintensityfactor(ksi,linch)forthe materiak,andwherethefactor1.5isconsistentwiththesafetyfactor required by 10 CFR Part 50. Appendix G. and ASME Appendix G for hydrostatic testing conditions,
- e. Calculate the membrane stress using the methodology of Appendix 5 to WRC Bulletin No. 175 1972 and the following equation:
/ ( F(a/r, ) * (n
- a)" )
(C-3) a, = Ki where K is the material stress intensity factor. F(a/r proportkonality factor to account for increases in the s) represents a tress intensity i
f O te e I
t f
2 l
factor due to geometric constraints', tht parameter "a" represents thg postulated flaw size (inches) used in the fracture mechanics analysis,
orboltomvesselhead.and a is the membrane stress (ksi) for the material in bel
- f. Calculate the minimum allowable pressure using the following membrane stress equations:
P - 1000 * (a,
- t) / R (C 4) j where P is the calculated reactor pressure (psi), o, bottom vessel h is the membrane stress (ksi) for the material in beltline region or t is the vessel shell thickness (inches), and r is the reactor vessel inner radius (inches),
g Repeat steps a, through f. using other assumed temperatures to generate P-T limit data for the nozzles, and subsequently establish the composite P T. limit curve for hydrostatic testing using the most conservative data from the evaluations of the limit materials in the beltline region of the reactor, the bottom vessel head, and the No. N16 A/B instrument nozzles (Note:
the methodology for the staff's analysis of the beltline region and the bottom vessel head is summarized in Appendix B).
- h. Compare the NRC generated P-T limit curve with the corresponding P T limit curve presented in the proposed amended Technical Specifications.
8 Appendix 5 of WRC Bulletin No. 175 1972 provides an acceptable method of evaluating the stress intensities in nozzles joined to reactor pressure vessel shells.
Fi determine the pro)gure A5 1 of Appendix 5 to the Bulletin may be used to ortionality factor f(a/r ) when used in a manner that is consistent wit 1 the Appendix's overall, recommended methodology.
.9 According to WRC Bulletin No. 175 1972, for evaluations of a nozzle
. joined to the beltline region of a reactor pressure vessel, the postulated flaw is a semi-elliptical surface flaw which init16tes from the inner surface-of the juncture between the nozzle and the shell cylinder.
The depth of this flaw is postulated to extend one guarter of the thickness of the nozzle along a line oriented at a 45' angle to the inner surface of the reactor pressure vessel shell. According to WRC Bulletin No. 175 1972, this juncture is a critical. location because the local membrane stress at this >oint produced by )ressure may be 2 to 3 times the magnitude of the mem)rane stress in otler locations of the shell.
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