ML040540672
| ML040540672 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 02/02/2004 |
| From: | Entergy Operations |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| CNRO-2004-00008 M-EP-2004-001, Rev 0 | |
| Download: ML040540672 (41) | |
Text
ENCLOSURE 1 CNRO-2004-00008 ARKANSAS NUCLEAR ONE, UNIT I RELAXATION REQUEST #1
ENTERGY OPERATIONS, INC.
ARKANSAS NUCLEAR ONE, UNIT I RELAXATION REQUEST #1 TO NRC ORDER EA-03-009 I.
ASME COMPONENTS AFFECTED Arkansas Nuclear One, Unit 1 (ANO-1) has sixty-nine (69) ASME Class 1 reactor pressure vessel (RPV) head penetration nozzles comprised of sixty-eight (68) control rod drive mechanism (CRDM) nozzles and one (1) radiation calibration instrumentation nozzle. Of these nozzles, eight (8) were repaired during the previous refueling outage; two (2) using a weld overlay repair and six (6) using a pressure boundary relocation repair. See Figure 1 for penetration locations on the ANO-1 RPV head.
In accordance with Section IV.B of NRC Order EA-03-009 (the Order), the ANO-1 susceptibility category is "high" because of cracking experienced in RPV head penetration nozzles and J-groove welds due to primary water stress corrosion cracking (PWSCC).
This request does not apply to the eight previously repaired nozzles. As described in Footnote 3 of Section IV.B(1) of the Order, the six nozzles repaired using the pressure boundary relocation repair technique (#s 3, 6, 15, 17, 35, and 56) will be ultrasonically examined as specified in Request for Alternative ANO1-R&R-004, which was authorized by the NRC staff.' The two nozzles repaired using the weld overlay technique (#s 54 and
- 68) will be examined by performing either an eddy current testing (ECT) or liquid penetrant testing (PT) examination on the weld overlay and the inside diameter (ID) of the nozzle blind zone. (See Section III for a discussion of the blind zone.)
- 11.
NRC ORDER EA-03-009 APPLICABLE EXAMINATION REQUIREMENTS The NRC issued Order EA-03-009 that modified the current licenses at nuclear facilities utilizing pressurized water reactors (PWRs), which includes ANO-1. The Order establishes inspection requirements for RPV head penetration nozzles. ANO-1 is categorized as a "high" susceptibility plant as discussed above.
Section IV.C of the Order states in part:
'All Licensees shall perform inspections of the RPV head using the following techniques and frequencies:
(1) For those plants in the High category, RPV head and head penetration nozzle inspections shall be performed using the following techniques every refueling outage.
(a) Bare metal visual examination of 100% of the RPV head surface (including 3600 around each RPV head penetration nozzle), AND 1 Letter from the NRC to Entergy Operations, Inc., Arkansas Nuclear One, Unit No. 1 - RE: Relief Request to use Alternative Techniques for Reactor Pressure Vessel Closure Head Nozzles (TAC No.
MB6599), dated November 25, 2003 Page 1 of 14
(b) Either:
(i) Ultrasonic testing of each RPV head penetration nozzle (i.e., nozzle base material) from two (2) inches above the J-groove weld to the bottom of the nozzle and an assessment to determine if leakage has occurred into the interference fit zone, OR (ii) Eddy current testing or dye penetrant testing of the wetted surface of each J-groove weld and RPV head penetration nozzle base material to at least two (2) inches above the J-groove weld."
Ill.
REASON FOR REQUEST Section IV.F of the Order states:
"Licensees proposing to deviate from the requirements of this Order shall seek relaxation of this Order pursuant to the procedure specified below. The Director, Office of Nuclear Reactor Regulation, may, in writing, relax or rescind any of the above conditions upon demonstration by the Licensee of good cause. A request for relaxation regarding inspection of specific nozzles shall also address the following criteria:
(1) The proposed alternative(s) for inspection of specific nozzles will provide an acceptable level of quality and safety, or (2) Compliance with this Order for specific nozzles would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety.
"Requests for relaxation associated with specific penetration nozzles will be evaluated by the NRC staff using its procedure for evaluating proposed alternatives to the ASME Code in accordance with 10 CFR 50.55a(a)(3)."
Pursuant to Section IV.F(2) of the Order, Entergy Operations, Inc. (Entergy) requests relaxation from the requirements of Section IV.C(1)(b) for the 61 ANO-1 RPV head penetration nozzles that have not been repaired. Entergy plans to inspect these nozzles using the ultrasonic testing (UT) method in accordance with Section IV.C(1)(b)(i) of the Order to the maximum extent possible. However, a UT inspection of the ID of the RPV head nozzles at ANO-1 can only be performed from 2 inches above the J-groove weld down to a point approximately 0.516 inch above the bottom of the nozzle. This 0.516-inch "blind zone" is due to a limitation resulting from inspection probe design. This limitation and its associated hardship are discussed below in Section III.A.
Entergy also evaluated the impact of inspecting the blind zone of each RPV head penetration nozzle using either the liquid penetrant testing (PT) method or the eddy current testing (ECT) method as specified in Section IV.C(11)(b)(ii) of the Order. Entergy found hardship associated with these techniques, as discussed in Section III.B.
Page 2 of 14
A.
Inspection Probe Design Limitation
- 1. Description The inspection probe to be used to inspect ANO-1 RPV head penetration nozzles consists of one (1) pair of ultrasonic time-of-flight diffraction (TOFD) transducers.
The inspection probe is designed so that the ultrasonic transducers are slightly recessed into the probe holder. This recess must be filled with water to provide coupling between the transducer and the nozzle wall. Because of this design, the complete diameter of the transducer must fully contact the inspection surface before ultrasonic information can be collected. Based on probe configuration, the transducer pair only collects meaningful data down to a point approximately 0.516 inch above the bottom end of the nozzle. Below this point, meaningful UT data cannot be collected.
- 2. Hardship Entergy knows of no UT equipment currently available that resolves the blind zone limitation; therefore, new UT equipment would have to be developed and appropriately qualified. The time and resources required to develop this equipment is unknown.
B. Hardship of Performing Alternative Surface Examinations To perform either a PT or ECT inspection of the bottom end of each RPV head nozzle would result in a significant increase in personnel radiation exposure. Entergy estimates that the radiation exposure associated with performing the PT or ECT inspection to be approximately 0.16 man-REM per nozzle for a total exposure of 11 man-REM. In addition, Entergy estimates that to perform an examination on the entire wetted surface of each nozzle in accordance with Section IV.C(b)(1)(ii) of the Order would require additional under-head time for preparation and application resulting in approximately 26.5 to 27 man-REM total exposure.
In conclusion, Entergy can volumetrically inspect the RPV head nozzles in accordance with Section IV.C(1)(b)(i) of the Order from 2 inches above the weld to the top of the blind zone. Below this point, Entergy believes that the hardships associated with inspection activities required by the Order as discussed above are not commensurate with the level of increased safety or reduction in probability of leakage that would be obtained by complying with the Order.
IV.
PROPOSED ALTERNATIVE AND BASIS FOR USE Paragraph IV.C(1)(b)(i) of the Order requires that the UT inspection of each RPV head penetration nozzle encompass "from two (2) inches above the J-groove weld to the bottom of the nozzle." Due to the reasons stated in Section III above, Entergy requests relaxation from this requirement for the ANO-1 RPV head penetration nozzles and proposes an alternative, which involves the use of UT examination and analysis, as described below.
Page 3 of 14
A.
Proposed Alternative
- 1. UT Examination The ID of each RPV head penetration nozzle (i.e., nozzle base material) shall be ultrasonically examined from two (2) inches above the weld to the blind zone portion above the bottom of the nozzle. In addition, an assessment to determine if leakage has occurred into the interference fit zone will be performed, as currently specified in Section IV.C(1)(b)(i) of the Order.
- 2. Analvsis For the blind zone portion of each RPV head penetration nozzle not examined by UT as required by the Order, analysis has been performed to determine if sufficient free-span lengths (uphill and downhill) exist between the blind zone and the weld to facilitate one (1) operating cycle of crack growth without the crack reaching the weld.
The analysis is summarized in Section IV.B.2 and is fully documented in Engineering Report M-EP-2004-001, Rev. 0 (Enclosure 2).
- 3. UT Verification of CRDM Nozzle 26 UT measurement data of the RPV head penetration nozzles obtained during the previous ANO-1 refueling outage was used to determine actual free-span lengths for the RPV head penetration nozzles. However, the storage data files containing the UT measurements for CRDM Nozzle 26 were found to be corrupted; therefore, its actual free-span lengths could not be determined. Because of this situation, Entergy will perform a UT examination on Nozzle 26 to determine its actual free-span lengths. If the free-span lengths meet the measured minimum free-span lengths for its associated nozzle group (26.20) (see table in Section IV.B.2), no further actions will be required. If the free-span lengths fail to meet the lengths, Entergy will perform an augmented examination of the blind zone portion of Nozzle 26 not examined by UT. This examination will consist of either ECT or PT, or a combination of both techniques. If performed, this augmented inspection will be included in the 60-day report required by Section IV.E of the Order.
B. Basis for Use The UT examination is the volumetric technique recognized in Section IV.C(1)(b)(i) of the Order. The proposed alternative includes the use of UT to the maximum extent practical based on the limits of current technology. However, because the technology cannot provide an inspection to the extent required by the Order (i.e., to the bottom of the nozzle), Entergy proposes supplemental analysis in addition to the UT examination. This approach provides a level of safety and quality commensurate with the intent of the Order. Each portion of the proposed alternative is discussed below.
Page 4 of 14
- 1. UT Examination Entergy will perform UT examination of the ANO-1 RPV head nozzles using the TOFD technique. The TOFD technique utilizes one pair of transducers aimed at each other looking in the axial direction of the penetration nozzle tube. One of the transducers sends sound into the inspection volume while the other receives the reflected and diffracted signals as they interact with the material. The TOFD technique is used to detect and characterize planar-type defects within the full volume of the tube.
The UT examination procedures and techniques to be utilized at ANO-1 have been satisfactorily demonstrated under the EPRI Materials Reliability Program (MRP) Inspection Demonstration Program.
- 2. Analysis The extent of the proposed alternative is established by an engineering evaluation that includes a finite element stress analysis and fracture mechanics evaluations. The intent of the engineering evaluation is to determine whether sufficient free-span lengths (uphill and downhill) exist between the blind zone and the weld to facilitate one operating cycle of crack growth without the crack reaching the weld. See Figure 2.
Four (4) RPV head penetration nozzle locations have been selected for analysis in the engineering evaluation. The selected location groups (RPV head angles) are 0°, 18.20, 26.20, and 38.50 with the 0° head angle at the vertical centerline of the RPV head, the 38.50 head angle location being the outermost nozzles, and the other two groups being intermediate locations between the center and outermost locations.
As discussed in Section IV.A.3 above, Entergy evaluated UT measurement data obtained during the previous ANO-1 refueling outage to determine actual free-span lengths of the nozzles. The storage data files containing the UT measurements for CRDM Nozzle 26 were found to be corrupted; therefore, its actual free-span lengths could not be determined. As such, it could not be encompassed within this analysis.
The measured minimum free-span lengths for each nozzle group are documented in Table 1 of Engineering Report M-EP-2004-001 (Enclosure 2) and are summarized below. The analysis indicated that every nozzle, except CRDM Nozzle 26, has adequate free-span lengths. Actions to be taken for Nozzle 26 are discussed in Section IV.A.3.
Page 5 of 14
Nozzle Nozzle Numbers Measured Minimum Measured Minimum Group in the Group Free-Span Length @
Free-Span Length @
Downhill Location Uphill Location 00 1.040 inches 1.040 inches 18.20 2 thru 21 0.430 inch 1.450 inches 26.20 22 thru 37 0.630 inch 2.840 inches 38.50 38 thru 69 0.440 inch 3.080 inches While evaluating the UT measurement data, Entergy discovered that the blind zone experienced during the previous nozzle examinations ranged from 0.589 inch to 1.818 inches depending on the specific nozzle location. This blind zone was due to (1) a limitation resulting from inspection probe design, and (2) probe lift-off encountered near the bottom of the nozzle while performing the UT examinations. With a redesign of the probe, the lift-off problems have been resolved. However, the probe design limitation is inherent to the technology.
(See a discussion in Section l1l.A, above.) For conservatism, the analysis was performed using the larger blind zone lengths determined from the UT measurement data.
The results of the stress analysis at each location are bounding for nozzles higher on the head (e.g., analysis for 26.20 bounds the intermediate nozzles between 18.20 and 26.20). The selected nozzle head angle locations provide an adequate representation of residual stress profiles and a proper basis for analysis to bound all RPV head nozzles. The stress analyses and fracture mechanics evaluations performed to address these conditions are summarized below.
Stress Analysis A "finite element" based stress analysis (FEA) is performed on the ANO-1 RPV head nozzle locations in this evaluation. For conservatism, the yield strength used in the analysis for each nozzle head angle location is the highest yield strength of the RPV head penetration nozzles. To ensure that the FEA adequately modeled the as-built configuration of the ANO-1 CRDM nozzles and welds, a detailed review of actual UT examination data from the previous refueling outage was performed.
The FEA for the analyzed nozzles determines the stress distribution from the bottom of the nozzle to just above the top of the weld at the downhill, uphill, and mid-plane azimuthal locations. The downhill and mid-plane locations are selected for analysis because they represent the shortest distances that a crack has to propagate to reach the nozzle weld region. The uphill location is selected for completeness of the analysis. The results of the FEA are presented in Figures 4 through 17 and Tables 2 through 11 of Engineering Report M-EP-2004-001 (Enclosure 2). The stress distributions produced by this analysis are used to perform the fracture mechanics evaluations.
Page 6 of 14
Fracture Mechanics Evaluation Safety analyses performed by the MRP have demonstrated that axial cracks in the nozzle tube material do not pose a challenge to the structural integrity of the nozzle. However, axial cracks may lead to pressure boundary leaks above the weld that could produce OD circumferential cracks and structural integrity concerns. Therefore, proper analysis of potential axial cracks in the blind zone of the RPV head nozzle is essential.
The analyses performed in the engineering evaluation are designed to determine the behavior of postulated cracks that could exist in the blind zone. Hence, the crack growth region is from the top of the blind zone to the bottom of the weld.
The design review of the RPV head construction, the detailed residual stress analysis, selection of representative nozzle locations, utilization of representative fracture mechanics models, and the application of a suitable crack growth law provide a sound basis for the engineering evaluation.
Postulated cracks for the analysis include axial ID and OD part through-wall and through-wall cracks. Axial cracks are selected for evaluation in this analysis because of their potential to propagate to the weld region. Axial ID and OD part through-wall crack sizes were larger than twice the smallest crack sizes successfully detected by UT under the EPRI MRP Inspection Demonstration Program. Part through-wall cracks are centered at the top of the blind zone in the analysis. Through-wall cracks are postulated to exist from the top of the blind zone down to a point where the hoop stress is < 10 ksi. The ID and OD part through-wall and through-wall cracks are located along the circumference of each nozzle at the 0° (downhill), 90° (mid-plane), and 1800 (uphill) azimuthal locations, 00 (downhill) the furthest point from the center of the RPV head.
Thirty (30) different cases have been analyzed using crack growth rates from EPRI Report MRP-55, Material Reliability Program - Crack Growth Rates for Evaluating Primary Water Stress Corrosion Cracking (PWSCC) of Thick-Wall Alloy 600 Material. In summary, the evaluation results from all cases demonstrate that postulated flaws in the blind zone region will not compromise the weld in one cycle of operation. As previously discussed, CRDM Nozzle 26 will be volumetrically examined to ensure it meets this evaluation. The analysis further demonstrates that a larger margin exists (i.e. longer than one fuel cycle) at all evaluated locations. At several locations that were analyzed, no PWSCC-induced crack growth was observed because the stress distribution at these locations produced stress intensity factors that were below the threshold value for crack propagation by PWSCC. For the limited cases where PWSCC crack growth was predicted, the crack growth in one cycle of operation did not challenge the weld. Results of the fracture mechanics evaluations are documented in Table 14 of Engineering Report M-EP-2004-001 (Enclosure 2) and summarized below.
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Nozzle Azimuth Crack Allowed Propagation Dimension Allowed GrowthlCycle Group Location Type
.(inch) 2 (inch)3 0
All ID 0.865 L/0.617 D 0 LI0 D OD 0.865 0
Thru-wall 1.044 0
18.20 Downhill ID 0.255 L/0.617 D 0.065 L/0.111 D OD 0.255 0.062 Thru-wall 0.430 0.313 Uphill ID 1.275 L/ 0.617 D 0.032 L/ 0.088 D OD 1.275 0
Thru-wall 1.45 0
Mid-plane ID 0.96 L /0.617 D 0 L /0 D OD 0.96 0
Thru-wall 1.135 0
26.20 Downhill ID 0.405 L / 0.617 D 0.041 L / 0.092 D OD 0.405 0
Thru-wall 0.58 0
Uphill ID 2.665 L/0.617 D 0 L/0 D OD 2.665 0
Thru-wall 2.84 0
Mid-plane ID 1.645 L / 0.617 D 0 L /0 D OD 1.645 0
Thru-wall 1.82 0
38.50 Downhill ID 0.265 L /0.617 D 0 L /0 D OD 0.265 0.010 Thru-wall 0.44 0
Uphill ID 2.905 L /0.617 D 0 L /0 D OD 2.905 0
Thru-wall 3.08 0
Mid-plane ID 1.805 L/0.617 D 0 L/ 0 D OD 1.805 0
Thru-wall 1.98 0
2 L = Length; D = Depth 3 Both L and D dimensions are given for surface cracks on the ID. The limiting condition is reached when the postulated crack becomes through-wall and the upper tip reaches the bottom of the weld. The allowable propagation length of the surface-connected crack, L, is equal to the actual (measured) free-span length minus 0.175 inch, which is the distance the crack extends into the free-span at the minimum detectable crack size.
Page 8 of 14
Additional Analyses The fracture mechanics evaluations described above assess the potential for postulated cracks to propagate from the top of the blind zone to the weld in less than one cycle of plant operation, assuming either an ID or OD crack with an initial length of approximately two (2) times the smallest detectable length, or a through-wall crack from the top of the blind zone down to a point where the hoop stress is < 1 0 ksi. Because the blind zone is significantly longer than the smallest detectable length, this approach did not consider ID or OD cracks that extend down to the bottom of the nozzle. This is appropriate if the hoop stress at the bottom of the postulated flaw is compressive or if the hoop stress is a low tensile stress (< 1 0 ksi), as these hoop stresses will not propagate PWSCC. For the through-wall cracks, in all cases, the hoop stress rapidly decreases below the blind zone such that none of the postulated though-wall cracks extend to the bottom of the nozzle.
The potential for postulated cracks to propagate from the bottom of the blind zone to the weld was also evaluated. In general, the stress analysis indicates that the magnitude of the hoop stress distribution from the top of the blind zone to the bottom of the nozzle along both the ID and OD surfaces decreases steadily and becomes compressive. The extent or height of the compression zone for each nozzle group and azimuthal location is presented in Table 13 of the Engineering Report M-EP-2004-001 (Enclosure 2) and is summarized below.
Nozzle Azimuthal Compression Maximum Hoop Stress Where No Group Location.
Zone Height Compression Zone Exists 00 All 0.56 inch N/A 18.20 Downhill 0.4 inch N/A Uphill 0.8 inch N/A Mid-plane 0.9 inch N/A 26.20 Downhill 0.357 inch N/A Uphill 0.953 inch N/A Mid-plane 0.875 inch N/A 38.50 Downhill 0.5 inch N/A Uphill 1.0 inch N/A Mid-plane 0
10.954 ksi The height of the compression zone is measured from the bottom of the nozzle.
Within the compression zone regions, no PWSCC-assisted crack growth is possible. For those nozzle groups with a tensile stress below 10 ksi, the possibility for PWSCC crack initiation is extremely low. Based on these stress profiles, only the 38.50 mid-plane location warrants additional analysis for crack growth below the postulated cracks discussed above.
Page 9 of 14
A hoop stress of 10.954 ksi exists along the ID surface at the bottom of the 38.50 nozzle at the mid-plane location. Because of this higher stress value, this nozzle location was selected for additional analysis by fracture mechanics. An ID surface crack was postulated near the bottom of the nozzle. The analysis showed that it would not propagate from PWSCC. However, the model for the surface crack is based on cracks that are remote from the edge of the plate.
Because of this, a through-wall edge crack at the bottom of the nozzle was also evaluated. Based on this analysis, postulated cracks at the bottom of the 38.50 nozzle (mid-plane) do not propagate into the weld in less than one cycle of plant operation was evaluated. Furthermore, the analysis results indicate that the postulated cracks in the region do not reach the weld in two (2) years of operation. For additional details, see the Additional Analysis subsection of Section 5.0 in Engineering Report M-EP-2004-001 (Enclosure 2).
Analysis Conclusions Fracture mechanics evaluations were performed at the downhill, uphill, and mid-plane locations of the 00, 18.20, 26.20, and 38.50 RPV head nozzles to assess the potential for postulated cracks to grow from the blind zone to the nozzle weld in less than one cycle of plant operation. Additional analyses were performed to assess the potential for postulated cracks to grow from along the bottom of the 38.50 nozzle at the mid-plane location to the weld in one cycle of operation.
The evaluations indicate that a crack in the blind zone of a nozzle will not grow into the weld of the nozzle within one cycle of operation. See Table 1 which identifies the nozzle locations bounded by these evaluations. For details regarding the engineering evaluation and its conclusions, see Engineering Report M-EP-2004-001 (Enclosure 2).
This analysis incorporates a crack-growth formula different from that described in Footnote 1 of the Order, as provided in EPRI Report MRP-55. Entergy is aware that the NRC staff has not yet completed a final assessment regarding the acceptability of the EPRI report. If the NRC staff finds that the crack-growth formula in MRP-55 is unacceptable, Entergy shall revise its analysis that justifies relaxation of the Order within 30 days after the NRC informs Entergy of an NRC-approved crack-growth formula. If Entergy's revised analysis shows that the crack growth acceptance criteria are exceeded prior to the end of Operating Cycle 19 (following the upcoming refueling outage), Entergy will, within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />, submit to the NRC written justification for continued operation. If the revised analysis shows that the crack growth acceptance criteria are exceeded during the subsequent operating cycle, Entergy shall, within 30 days, submit the revised analysis for NRC review. If the revised analysis shows that the crack growth acceptance criteria are not exceeded during either Operating Cycle 19 or the subsequent operating cycle, Entergy shall, within 30 days, submit a letter to the NRC confirming that its analysis has been revised. Any future crack-growth analyses performed for Operating Cycle 19 and future cycles for RPV head penetrations will be based on an NRC-acceptable crack growth rate formula.
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- 3. UT Verification of CRDM Nozzle 26 As stated in Section IV.A.3, above, the data files containing UT measurements for CRDM Nozzle 26 were corrupted thereby preventing Entergy from determining its actual free-span lengths. By performing a UT examination to verify that the free-span lengths of the nozzle meet the acceptance criteria, Entergy will demonstrate that an undetected crack in the blind zone will not reach the nozzle's J-groove weld within one (1) operating cycle.
In the event that a free-span length does not meet its acceptance criterion, the augmented examination of the blind zone ensures that a crack within the blind zone will be detected.
V.
CONCLUSION Section IV.F of the Order states:
"Licensees proposing to deviate from the requirements of this Order shall seek relaxation of this Order pursuant to the procedure specified below. The Director, Office of Nuclear Reactor Regulation, may, in writing, relax or rescind any of the above conditions upon demonstration by the Licensee of good cause. A request for relaxation regarding inspection of specific nozzles shall also address the following criteria:
(1) The proposed alternative(s) for inspection of specific nozzles will provide an acceptable level of quality and safety, or (2) Compliance with this Order for specific nozzles would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety."
Section IV.C(1)(b) of the Order establishes a minimum set of RPV head penetration nozzle inspection requirements to identify the presence of cracks in penetration nozzles that could lead to leakage of reactor coolant and wastage of RPV head material.
Entergy believes that compliance with the UT inspection provisions of Section IV.C(1)(b)(i) of the Order as described in Section II above would result in hardships and unusual difficulties, as discussed in Section III above, without a compensating increase in the level of quality and safety.
Entergy believes the proposed alternative, described in Section IV, provides an acceptable level of quality and safety by utilizing inspections and analysis to determine the condition of the ANO-1 RPV head penetration nozzles. The technical basis for the analysis of the proposed alternative is documented in Engineering Report M-EP-2004-001, Rev. 0, which is contained in Enclosure 2 of this letter. Entergy believes that by employing analytical and inspection techniques, the two-step proposed alternative provides an adequate process for inspecting, evaluating, and determining the condition of the ANO-1 RPV head penetration nozzles with regard to the presence of PWSCC.
Entergy concludes that the proposed alternative adequately meets the intent of the Order.
Therefore, we request that the NRC staff authorize the proposed alternative pursuant to Section IV.F of the Order.
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TABLE 1 Results of Crack Growth Analysis Nozzle Nozzle Azimuth Axial Crack Crack Evaluation Results Location Location Evaluated 00 All ID Part through-wall No PWSCC growth OD Part through-wall No PWSCC growth Through-wall No PWSCC growth 18.20 Downhill ID Part through-wall Greater than 1 Cycle to reach weld OD Part through-wall Greater than 1 Cycle to reach weld Through-wall Greater than 1 Cycle to reach weld Uphill ID Part through-wall No PWSCC growth OD Part through-wall No PWSCC growth Through-wall No PWSCC growth Mid-plane ID Part through-wall No PWSCC growth OD Part through-wall No PWSCC growth Through-wall No PWSCC growth 26.20 Downhill ID Part through-wall Greater than 1 Cycle to reach weld OD Part through-wall No PWSCC growth Through-wall Greater than 1 Cycle to reach weld Uphill ID Part through-wall No PWSCC growth OD Part through-wall No PWSCC growth Through-wall No PWSCC growth Mid-plane ID Part through-wall No PWSCC growth OD Part through-wall No PWSCC growth Through-wall No PWSCC growth 38.50 Downhill ID Part through-wall No PWSCC growth OD Part through-wall Greater than 1 Cycle to reach weld Through-wall No PWSCC growth Uphill ID Part through-wall No PWSCC growth OD Part through-wall No PWSCC growth Through-wall No PWSCC growth Mid-plane ID Part through-wall No PWSCC growth OD Part through-wall No PWSCC growth Through-wall No PWSCC growth Page 12 of 14
RPV Head Penetration Nozzles Radiation Calibration Instrument nozzle: I CRDM nozzles: 2 - 69 Previously Repaired Nozzles Weld Overlay: 54 and 68 Pressure Boundary Relocation: 3, 6, 15,17, 35, & 56 FIGURE 1 CRDM NOZZLE LOCATIONS ON THE ANO-1 RPV HEAD Page 13 of 14
CRDM RPV Head Cladding Nozzle UT Inspectablk Region Free-Span roove
'eld Blind Zone FIGURE 2 CRDM NOZZLE CONFIGURATION J-Grw Page 14 of 14
ENCLOSURE 2 CNRO-2004-00008 ENGINEERING REPORT M-EP-2004-001, REV. 0 FRACTURE MECHANICS ANALYSIS FOR THE ASSESSMENT OF THE POTENTIAL FOR PRIMARY WATER STRESS CORROSION CRACK (PWSCC)
GROWTH IN THE UNINSPECTED REGIONS OF THE REACTOR PRESSURE VESSEL HEAD NOZZLES AT ARKANSAS NUCLEAR ONE, UNIT 1
Engineering Report No.
M-EP-2004-O0 1 Page I
Rev.
00 of 54
~En tergy ENTERGY NUCLEAR SOUTH Engineering Report Coversheet Fracture Mechanics Analysis for the Assessment of the Potential for Primary Water Stress Corrosion Crack (PWbVSCC) Growth in the Un-Inspected Regions of the Control Rod Drive Mechanism (CRDM) Nozzles at Arkansas Nuclear One Unit I Engineering Report Type:
New X
Revision Deleted El Superceded El Applicable Site(s)
ANO X
Echelon X
GGNS E
RBS l
W F3 Report Origin:
X ENS El Vendor Vendor Document No.
Safety-Related:
X Yes El No Prepared by:
g,,
Verified.'
Reviewed by:
LV ResElrsible Engineer YkGc xxL/.
Comments:
Date:
0 Yes I/ lZ 7/by E No Date:
_I __
/° l
El No Date:
El Yes El-No Attached:
El Yes M No El Yes El Yes H-No Desi eviewer I Approved by:
Responsible Supervisor or Responsible Central Engineering Manager (for multiple site reports only)
Engineering Report M-EP-2004-001 Rev.
00 Page 2 of 54 E-M-EP-2004-O01 Engineering Report No.
00 Rev.
of 54 Page 2
RECOMMENDATION FOR APPROVAL FORM Prepared by:
Concurrence:
Concurrence:
Concurrence:
Concurrence:
Responsible Engineer Rcsponsiblofgieing Managcr, AN0 Not Applicable Comments:
Date:
El Yes O No Date:
1/29/0,'
5 Yes
[gNo Date: __________
El Yes Date:
E_ Yes Q No Date:
El Yes
[] No Attached:
O] Yes E No E Yes FBNo El No D Yes El No al Yes El No Responsible Engineering Manager, GGNS Not Applicable Responsible Engineering Manager, RBS Not Applicable Responsible Engineering Manager, WF3
Engineering Report M-EP-2004-001 Rev. 00 Page 3 of 54 Table of Contents Section Title Page Number List of Tables 3
List of Figures 4
List of Appendices 5
1.0 Introduction 6
2.0 Stress Analysis 1 0 3.0 Analytical Basis for Fracture Mechanics and Crack Growth 26 Models 4.0 Method of Analysis 31 5.0 Discussion and Results 36 6.0 Conclusions 52 7.0 References 54 List of Tables Table Number Title Page Number I
Minimum freespan length for the nozzle group used in the current 9
evaluation.
2 Nodal Stress data for 00 Nozzle.
16 3
Nodal Stress data for the 18.20 nozzle at the downhill location.
17 4
Nodal Stress data for the 18.20 nozzle at the uphill location 18 5
Nodal Stress data for the 18.20 nozzle at the mid-plane location.
19 6
Nodal Stress data for the 26.20 nozzle at the downhill location.
20 7
Nodal Stress data for the 26.20 nozzle at the uphill location.
21 8
Nodal Stress data for the 26.20 nozzle at the mid-plane location.
22 9
Nodal Stress data for the 38.50 nozzle at the downhill location.
23 10 Nodal Stress data for the 38.50 nozzle at the uphill location.
24 11 Nodal Stress data for the 38.50 nozzle at the mid-plane location.
25 12 Comparison of Fracture Mechanics Models 41 13 Results for compression zone 42 14 ANO-1 Estimated As-Built Analyses Results Summary 44
Engineering Report M-EP-2004-001 Rev. 00 Page 4 of 54 List of Figures Figure Title Page Number Number 1
Sketch showing CRDM penetration 7
2 Sketch of a typical inspection probe sled [3a].
8 3
Finite element model of the 38.50 nozzle 11 4
Hoop Stress contours for the 00 nozzle.
13 5
Hoop Stress contours for the 18.2° nozzle.
13 6
Hoop Stress contours for the 26.20 nozzle.
14 7
Hoop Stress contours for the 38.50 nozzle.
14 8
Plot showing hoop stress distribution along tube axis for the 00 nozzle.
16 9
Plot showing hoop stress distribution along tube axis for the 18.20 nozzle 17 at the downhill location.
10 Plot showing hoop stress distribution along tube axis for the 18.20 nozzle 18 at the uphill location.
11 Plot showing hoop stress distribution along tube axis for the 18.20 nozzle 19 at mid-plane location.
12 Plot showing hoop stress distribution along tube axis for the 26.20 nozzle 20 at the downhill location.
13 Plot showing hoop stress distribution along tube axis for the 26.20 nozzle 21 at the uphill location.
14 Plot showing hoop stress distribution along tube axis for the 26.20 nozzle 22 at the mid-plane location.
15 Plot showing hoop stress distribution along tube axis for the 38.50 nozzle 23 at the downhill location.
16 Plot showing hoop stress distribution along tube axis for the 38.50 nozzle 24 at the uphill location..
17 Plot showing hoop stress distribution along tube axis for the 38.50 nozzle 25 at the mid-plane location.
18 SICF shown as a function of normalized crack depth for the a-tip" and the 27 "c-tip" 19 Curve fit equations for the 'extension and bending" components in 30 Reference 6.
20 Plots showing effect of nodal data selection on the accuracy of polynomial 34 regression fit, 21 Comparison of SICF for the edge crack configurations with the membrane 39 SICF for current model.
22 Comparison of SIF for the current model and conventional model.
40 23 SIF comparison between current model and conventional model.
40
Engineering Report M-EP-2004-001 Rev. 00 Page 5 of 54 List of Figures (Continued)
Figure Title Page Number Number 24 ID surface crack for nozzle group 18.20 at downhill location.
45 25 OD surface crack for nozzle group 18.20 at downhill location.
46 26 Through-wall crack for nozzle group 18.20 at downhill location.
46 27 ID surface crack for nozzle group 18.20 at uphill location.
47 28 ID surface crack for nozzle group 26.20 at downhill location.
48 29 Through-wall crack for nozzle group 26.20 at downhill location.
48 30 OD surface crack for nozzle group 38.50 at downhill location.
49 31 Nozzle group 38.50 at mid-plane location.
50 32 Nozzle group 38.50 at mid-plane location ID surface crack.
51 33 Nozzle group 38.50 at mid-plane location with an edge crack.
52 List of Appendices Appendix Content of Appendix Number of Number Attachments in Appendix A
Design Information and UT analysis results, 2
B Mathcad worksheets annotated to describe the three models 3
C Mathcad worksheets for ANO-1 Analyses 32 D
Verification and Comparisons (Mathcad worksheets) 6
Engineering Report M-EP-2004-001 Rev. 00 Page 6 of 54 1.0 Introduction The US Nuclear Regulatory Commission (NRC) issued Order EA-03-009 [1],
which modified licenses, requiring inspection reactor vessel head (RVH) penetrations, which includes Control Rod Drive Mechanism (CRDM) penetrations at nuclear facilities utilizing pressurized water reactors (PWRs). Paragraph IV.C.1.b of the Order requires the inspection to cover a region from the bottom of the nozzle to two (2.0) inches above the J-groove weld. In the Babcock & Wilcox (B&W) reactor vessel design the CRDM nozzles are tubular penetrations into RVH that are joined to the RVH by a J-groove weld. The typical CRDM connection is shown in Figure 1.
The design of the ultrasonic testing (UT) probes results in a region above the bottom of the nozzle (shown in Figure 1 as "blind zone") that cannot be inspected. Therefore, the region of the CRDM base metal that can be inspected begins above the blind zone and extends to two (2.0) inches above the J-groove weld. The unexamined length (here after called the blind zone) was obtained from a review of the UT data from the previous inspection campaign. From this review the highest value for the blind zone for a group of nozzles was used in the current analysis. The terms used in this report are defined as follows:
- Freespan = (bottom of weld - blind zone); this area below the weld is accessible for volumetric examination.
- Available Propagation Length = (bottom of weld -top of crack tip); area available for crack growth.
Note: For an outside diameter (OD) surface crack, this length is always less than the freespan; for through-wall it is equal to the freespan; and, for an inside diameter (ID) surface crack, the criterion is the propagation length and a through-wall penetration condition.
The nozzle as-built dimensions were determined by a detailed review of UT data from the previous inspection and design information for Arkansas Nuclear One Unit 1 (ANO-1), which are documented in Appendix "A". The finite element model to obtain the prevailing stress distributions (Residual+Operating) that are to be used in the deterministic fracture mechanics analyses were obtained from the analysis that were performed to support the inspection campaign during the previous refueling outage. The deterministic fracture mechanics analyses, in turn, assess the potential for primary water stress corrosion cracking (PWSCC) in the blind zone of the nozzles.
The details of the stress analysis including the finite element models are discussed in Section 2. The UT data from Arkansas Nuclear One Unit 1 (ANO-1) was used to establish the available freespan length, which are documented in Appendix "A".
In order to exclude the blind zone from the inspection campaign, a relaxation of the Order is required pursuant to the requirements prescribed in Section IV.F and footnote 2 of the Order [1].
The purpose of this engineering report is to provide detailed analyses to support a relaxation request. The work plan developed for the analyses were as follows:
Engineering Report M-EP-2004-001 Rev.
00 Page 7 of 54
- 1. Determine if sufficient propagation length between the blind zone and the weld exists to facilitate one (1) cycle of axial crack growth without the crack reaching the weld; and,
- 2. For nozzles not meeting 1 above, determine how much of the blind zone combined with the available freespan is required to facilitate one (1) cycle of crack growth without the crack reaching the weld. This area is subject to augmented surface examination.
Figure 1 below shows the general arrangement of the CRDM nozzles with connection details. In this figure the various regions are defined. This figure provides a general overview of the CRDM penetration and the regions planned for volumetric inspection, and the regions that cannot be inspected (blind zone) by the volumetric UT method.
Blind Zone Figure 1: Sketch showing a CRDM penetration. Typical freespan is shown on the downhill side, the freespan length on the uphill side would be considerable larger. The blind zone, based on inspection probe design is also shown.
Engineering Report M-EP-2004-001 Rev. 00 Page 8 of 54 The UT blind zone, determined to be approximately 0.400 inch above the bottom of the nozzle, is based on a typical inspection probe sled design (shown in Figure 2). However, based on the previous refueling outage inspections, the measured freespan indicated a larger blind zone to exist. This was attributed to the lift-off effect at the bottom of the nozzle. In the current analysis the shortest measured freespan for each nozzle group was used to establish the blind zone. The UT data analysis results are documented in of Appendix ' TK.
CRDM Nozzle 24 mm -o
-o Blind Zone UT Inspection Probe Schematic See table below for transducer information.
Position Mode l Diameter.
Description 1
Transmit 0.25 inch Axial Scan Using TOFD 2
Receive 0.25 inch Axial Scan Using TOFD Figure 2: Sketch of a typical inspection probe sled. The blind zone indicated on the sketch was determined from an analysis of the UT inspection data obtained from the inspection performed during the previous refueling outage.
Engineering Report M-EP-2004-001 Rev. 00 Page 9 of 54 The residual stress analysis, discussed in the next section, was performed for four nozzle groups to represent the various nozzle penetration head angles. The UT analysis results (Appendix "A") was reviewed and the minimum freespan length for each of the nozzle groups is shown in Table 1 below.
Nozzle Group Nozzle Number Minimum Freespan Minimum Freespan Penetration Angle In the Length @ Downhill Length @ Uphill Location Location (Degrees)
- Group, (inch)
(inch) 0 1
1.040 1.040 18.2 2 through 21 0.430 1.450 26.2 22 through 37 0.580 2.840 38.5 38 through 69 0.440 3.080 Table 1: Minimum freespan length for the nozzle group used in the current evaluation.
The analysis applied to determine the impact of not examining the blind zone independently evaluates a part through-wall axial crack initiated from the ID, a part through-wall axial crack initiated from the OD, and a through-wall axial crack.
Part Through-Wall Cracks The initial crack depth obtained from Reference 2 is 11.0% of wall thickness deep for an ID axial crack and 16% of wall thickness deep for an OD axial crack. The crack length is based on the detected length of 4 mm (0.157 inch) from Reference 2. In the deterministic fracture mechanics analyses, the part through-wall crack lengths are more than doubled to 0.35 inch and the crack center is located at the top of the blind zone. Thus, the crack spans both the blind zone and the inspectable region. The postulated crack sizes and depths are two times the detectable limits with one-half (0.175 inch) of the flaw length being located in the examinable area. This provides for a conservative evaluation because:
A)
By extending the postulated crack 0.175 inch into the inspectable region, it places the crack tip closer to the weld where the hoop stresses are higher; and B)
It assumes that 0.175 inch of the inspectable region is already cracked, reducing the remaining area for crack propagation.
Through-Wall Crack In addition to evaluating the part through-wall cracks, this evaluation also conservatively evaluates a through-wall axial crack. The through-wall axial
Engineering Report M-EP-2004-001 Rev. 00 Page 10 of 54 crack is postulated to exist from the top of the blind zone down to a point where the hoop stress is < 10 ksi. This is a very conservative assumption, since for a crack to initiate on the surface and propagate through-wall while being totally contained within the blind zone would result in an unrealistic aspect ratio. As can be concluded from the following analysis, the length of a part through-wall crack would propagate into the inspectable region long before its depth reaches a through-wall condition. However, evaluation of the through-wall crack provides completeness to this assessment and ensures all plausible crack propagation modes are considered. Like the part through-wall crack, the hoop stresses at the top of the blind zone were used as the initial stress with adjustments to account for the increased stresses as the crack approaches the weld.
The analyses include a finite element stress analysis of the CRDM nozzles and a fracture mechanics-based crack growth analysis for PWSCC. These analyses are performed for four nozzles (the nozzles were chosen at four head angles; 00, 18.20, 26.20, and 38.50) in the reactor vessel head to account for the varied geometry of the nozzle penetration. In this manner the analysis provides a bounding evaluation for all CRDM nozzles in the reactor vessel head. The sections that follow contain a description of the analyses, the results, and conclusions supported by the analyses.
2.0 Stress Analysis The residual stress existing in the nozzle at the J-groove weld has been extensively studied [3a]. These studies show that the residual stresses present in the nozzle tube are sufficiently high to warrant analysis for PWSCC induced crack growth.
The propensity for PWSCC initiation and propagation depends on the residual stress distribution and its magnitude. Therefore, finite element-based stress analyses for ANO-1 CRDM penetrations using the highest tensile yield strength were performed
[3b]. The nozzle groups considered were 00, 18.20, 26.20, and 38.5 °. The dimensions for the model were obtained from ANO-1 design drawings that are documented in Reference 3b. The finite element model of the 38.50 nozzle is shown in Figure 3. The models for the other nozzle groups were constructed in a similar manner. The model defines one half of the full nozzle since the nozzle is symmetrical about a vertical plane that bisects the nozzle along a line drawn from the downhill to uphill location.
Fine mesh was used in the critical regions of the J-groove weld. The nozzle tube wall was modeled with four elements in the thickness direction. Thus the stress distribution across the wall could be accurately estimated. The RVH surrounding the nozzle was modeled in sufficient detail to account for the interaction between the nozzle and the RVH.
Engineering Report M-EP-2004-001 Rev. 00 Page 11 of 54 2 305 2-06 (shelIl)
I)Donhill PlaIne NQdes are W's Series IPhill r
'Ianc Nodes are X).(O)t %sries
£0605
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- ~
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- nes sat 'hi II)nzvrxl A IukOI)i In meld non m 6'sat ShelI I) ah )c "eld rugimn i5's at edge orhidi edxtiwui 2-15 Neu Nri-iNmhers Increae b) I ikJ kiiedi tha tube Act shdl Nuke Numbers Increse by I ahlng theI tNub and shell ramius
- 015 715 Figure 3: Finite element model of the 38.50 nozzle. Fine mesh geometry at the location of interest can be noted. Sufficient region of the RVH, surrounding the nozzle, is incorporated to ensure the accuracy of the analyses.
The finite element modeling for obtaining the necessary stress (residual+operating) distribution for use in fracture mechanics analysis followed the process and methodology described in Reference 3a. The modeling steps were as follows:
- 1)
The finite element mesh consisted of 3-dimensional solid (brick) elements.
Four elements were used to model the tube wall and similar refinement was carried to the attaching J-weld.
- 2)
The CRDM tube material was modeled with a monotonic stress-strain curve. The highest yield strength from the nozzle material bounded by the nozzle group was used. This yield strength was referenced to the room temperature yield strength of the stress-strain curve described in Reference 5a. The temperature dependent stress-strain curves were obtained by
Engineering Report M-EP-2004-001 Rev. 00 Page 12 of 54 indexing the temperature dependent drop of yield strength.
- 3)
The weld material was modeled as elastic-perfectly plastic for the weld simulation. This approximation is considered reasonable since most of the plastic strain in the weld metal occurs at high temperatures where metals do not work-harden significantly (Reference 3c). The temperature in the weld is high during the welding process. Once the weld begins to cool, the temperatures in the weld at which strain hardening would persist are of limited duration (Reference 3c). This was borne out by the comparison between the analysis based residual stress distribution and that obtained from experiments (Reference 3d).
- 4)
The weld is simulated by two passes based on studies presented in Reference 3a.
- 5)
After completing the weld, a simulated hydro-test load step is applied to the model. The hydro-test step followed the fabrication practice.
- 6)
The model is then subjected to a normal operating schedule of normal heat up to steady state conditions at operating pressure. The residual plus operating stresses, once steady state has been achieved, are obtained for further analysis. The nodal stresses of interest are stored in an output file.
These stresses are then transferred to an Excel spreadsheet for use in fracture mechanics analysis [3b].
The stress contours for the four nozzle groups obtained from the finite element analysis are presented in Figures 4 through 7. The stress contour color scheme is as follows:
Dark Navy blue from Minimum (Compression) to -10 ksi Royal blue from -10 to 0 ksi Light blue from 0 to 10 ksi Light green from 10 to 20 ksi Green from 20 to 30 ksi Yellow green from 30 to 40 ksi from 40 to 50 ksi Red from 50 to 100 ksi 0Crt
Engineering Report M-EP-2004-001 Rev. 00 Page 13 of 54 Full Cross-section Zoomed in right weld Figure 4: Hoop stress contours for the 0° nozzle. High tensile stresses occur in the weld and adjacent tube material. The bottom of the tube is in compression.
Zoomed in Downhill side Full cross-section Figure 5: Hoop stress contours for the 18.2° nozzle. High tensile stresses occur in the weld and adjacent tube material. The bottom of the tube is in compression.
Engineering Report M-EP-2004-001 Rev. 00 Page 14 of 54 Full cross-section Zoomed in Downhill side Figure 6: Hoop stress contours for the 26.20 nozzle. High tensile stresses occur in the weld and adjacent tube material. The bottom of the tube is in compression.
Full cross-section Zoomed in Downhill side Figure 7: Hoop stress contours for the 38.50 nozzle. High tensile stresses occur in the weld and adjacent tube material. The bottom of the tube is in compression.
coQQa
Engineering Report M-EP-2004-001 Rev. 00 Page 15 of 54 The nodal stresses for the locations of interest in each of the four nozzle groups were provided by Dominion Engineering Inc. and were tabulated in Reference 3b. The nodal stresses and associated figures representing the OD and ID distributions along the tube axis are presented in tables and associated figures in the following pages. The location of the weld bottom was maintained at the node row ending with "601". The blind zone location is shown on the associated figure. The three azimuthal locations downhill (00), uphill (1800), and mid-plane (900) are shown in the figures presented in the following pages. The zone of compressive stress is shown in the figure to be in the lower left quadrant that is bounded by the two dashed lines.
From the tables and associated figures, a full visualization of the stress distribution in the nozzle, from the nozzle bottom (located at 0.0 inch) to the J-weld is obtained. These figures are also shown in the Mathcad worksheets provided in the Appendix "C" attachments. The nodal stress distribution, provided by Dominion Engineering, is used to establish the region of interest and the associated stress distribution that will be utilized in the subsequent analyses. In the three nozzle groups (00, 18.20 and 26.20) there exists a well defined compression zone. For the higher angle nozzle group (38.50 at the mid-plane location) tensile stresses were found to exist at the nozzle bottom. Hence there was no well defined compression zone in this nozzle. In this particular case the tension stress magnitude was low (-10.0 ksi), and the distribution through the wall thickness had compressive stresses. For this nozzle location the presence of a low magnitude tensile stress on one surface is not expected to cause PWSCC initiation. However, this location was selected for further evaluation using deterministic fracture mechanics and is discussed in a later section.
In the following pages, the stress data from the Excel spreadsheet provided by Dominion Engineering (Reference 3b) and plots representing the axial distribution at the ID and OD locations are presented for each nozzle group with the specific azimuthal location that is evaluated. The location of the compression zone the blind zone and bottom of the weld are marked by colored reference lines.
Engineering Report M-EP-2004-001 Rev. 00 Page 16 of 54 1
0. 000 101 0.441 201 0. 793 301 1.076 401 1.303 501 1.484
-30.99
-2.37 27.862 42.802 47.376
- 48. 173
-30.92
-4.15 23.567 38.705 40.949 40.841
-31.719
-6.024 19.705 32.039 35.624 37.026
!MMA
-35.433
-7.411 17.995 24.149 31.779 40.902
-35.967
-9.003 12.782 15.988 29.726 48.506 I
701 1.794 35.074 35.427 38.776 48.731 61.472 801 1.959 25.697 30.809 38.834 51.732 66.515 901 2.124 19.183 27.111 38.578 52.687 65.89 1001 2.288 18.854 25.754 38.057 52.967 65.445 1101 2.453 24.413 27.433 37.441 48.615 62.275 1201 2.618 31.382 31.231 36.808 46.394 54.749 Table 2: Nodal stress for 00 nozzle. This nozzle is symmetric about the nozzle axis hence these stresses prevail over the entire circumference. The weld location is shown by the shaded row.
Hoop Stress Plot 70 ID Hoop Stress OD Hoop Stress 50 l0 Top of Blind Zone
£0 Z
0 one~ld~
-50 0.0 0.5 1.0 1.5 2.0 Distance from Nozzle Bottom {inch}
Figure 8: Plot showing hoop stress distribution along tube axis for the 0O nozzle. The compression zone, the top of blind zone, and the bottom of the weld are shown.
COLD-
Engineering Report M-EP-2004-001 Rev. 00 Page 17 of 54 Row Hiht.
1
- 0. 000 101 0.463 201 0.834 301 1.131 401 1.369 501 1.560 I d
-32.98 4.418 23.603 39.381 41.077 35.472
-29.552 1.431 20.133 33.757 35.596 35.035
-27.619
-2.622 17.472 28.588 32.564 34.721
-25.631
-5.982 13.58 23.549 29.095 41.389 0
OD-;0;
-23.659
-7.485 8.558 16.901 28.069 51.476
M 701 1.854 18.476 26.759 37.578 49.667 67.274 801 1.996 15.182 24.435 37.506 53.17 72.592 901 2.138 16.043 22.797 36.698 51.389 59.83 1001 2.279 21.021 24.935 35.705 50.631 66.676 1101 2.421 26.705 26.535 36.109 44.384 53.376 1201 2.563 31.334 31.319 34.356 42.349 43.153 Table 3: Nodal stress for 18.20 nozzle at the downhill location. The weld location is shown by the shaded row.
Hoop Stress Plot 70
~
ID Hoqp Stress 7
OD Hdop Stress Top of Blind Zone
~30-0 0----.---.---.-.--~-.------------
-10 Bottorm of 'Weld Compresson Zone
-50 I
0.3 0.8 1.3 1.8 Distance from Nozzle Bottom {inch)
Figure 9: Plot showing hoop stress distribution along tube axis for the 18.20 nozzle at the downhill location. The compression zone, the top of blind zone, and the bottom of the weld are shown.
Engineering Report M-EP-2004-001 Rev. 00 Page 18 of 54 RSo w 80001 80101 80201 80301 80401 80501
- 0. 000 0.862 1.553 2.106 2.549 2.904
-15.271
-1.538 18.053 35.538 46.071 52.65
&..I R
-13.45
-5.725 15.629 34.972 44.442 44.403
-13.143
-10.568 3.72 26.87 37.478 37.227 I
-12.825
-14.254
-8. 133 5.376 23.453 37.55 Ma ;~W w
-12.103
-17.443
-16.919
-11.03 13.214 44.134 80701 3.354 39.228 41.11 47.652 80801 3.520 31.415 39.177 50.091 80901 3.685 28.557 36.461 51.385 81001 3.851 30.354 37.802 51.087 81101 4.016 35.974 41.093 49.888 81201 4.182 42.147 43.54 46.913 Table 4: Nodal stress for 18.20 nozzle the uphill location.
row.
62.239 78.684 65.872 77.544 66.316 67.807 65.419 76.035 60.979 73.541 55.231 65.515 The weld location is shown by the shaded Hoop Stress Plot 80 60 40 0
0)
CO C.
o 20 0
0
-20 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 Distance from Nozzle Bottom {inch}
Figure 10: Plot showing hoop stress distribution along tube axis for the 18.20 nozzle at the uphill location. The compression zone, the top of blind zone, and the bottom of the weld are shown.
CIO
Engineering Report M-EP-2004-001 Rev. 00 Page 19 of 54 Row Height :
ID 2%
50%
75%
00 40001 0.000
-15.876
-15.441
-15.26
-15.231
-15.607 40101 0.663
-2.577
-4.464
-6.327
-7.14
-7.152 40201 1.195 21.151 16.903 11.759 6.124
-0.117 40301 1.621 34.299 30.828 23.931 13.978 5.113 40401 1.962 39.982 32.343 27.07 23.686 19.206 40501 2.235 33.912 29.598 28.456 33.513 42.338 40701 2.608 12.376 21.274 32.036 47.198 65.639 40801 2.761 7.853 19.169 32.443 49.488 67.334 40901 2.915 8.241 17.942 33.09 49.776 59.722 41001 3.069 12.022 20.283 32.869 47.255 62.581 41101 3.222 21.093 22.953 33.495 44.425 57.425 41201 3.376 29.386 27.197 32.222 42.642 50.772 Table 5: Nodal stress for 18.20 nozzle at mid-plane location. The weld location is shown by the shaded row.
Hoop Stress Plot
-o--
ID Hoop Stress 60
-6.-- OD Hoop Stress 40 -
U)
Top of Blind Zone U) 20 0.
00
-20 0.0 0.5 1.0 1.5 2.0 Distance trom Nozzle Bottom {inch}
2.5 3.0 Figure 11: Plot showing hoop stress distribution along tube axis for the 18.20 nozzle at mid-plane location. The compression zone, the top of blind zone, and the bottom of the weld are shown.
CQ07
Engineering Report M-EP-2004-001 Rev. 00 Page 20 of 54 Row Hc eight ID-;
25%3 1
0.000
-30.999
-27.023 101 0.428 4.34 1.335 201 0.770 14.732 13.5 301 1.045 29.692 25.968 401 1.265 38.185 33.752 501 1.441 34.205 33.736
-25.148
-2.685 13.201 23.306 31.17 33.768
-23.031
-5.687 8.377 20.778 27.204 42.178
-20.485
-6.873 2.376 13.225 22.26 52. 957 I
701 1.721 17.898 26.785 37.376 49.171 62.922 801 1.859 14.141 23.872 37.125 51.822 72.266 901 1.997 14.142 21.901 36.565 50.51 60.668 1001 2.136 18.477 23.68 35.651 50.883 68.048 1101 2.274 22.153 24.584 35.784 43.92 49.437 1201 2.412 26.389 29.517 31.718 38.942 34.145 Table 6: Nodal stress for 26.20 nozzle at the downhill location. The weld location is shown by the shaded row.
Hoop Stress Plot 70 0-ID Hpop Stress 70 -
l^
O5:9 OD F~oop Stress
/
i Top of Blind Zone 0
/
030 f
i Bodornm of VWbid Coprsio Zon i
-50 0.3 0.8 1.3 1.8 Distance from Nozzle Bottom {inch}
Figure 12: Plot showing hoop stress distribution along tube axis for the 26.20 nozzle at the downhill location. The compression zone, the top of blind zone, and the bottom of the weld are shown.
CWx
Engineering Report M-EP-2004-001 Rev. 00 Page 21 of 54 Row 80001 80101 802 01 80301 80401 80501
- Height.
0. 000 1.025 1.847 2.505 3.032 3.454
-12.934 0.519 16.931 34.465 45.126 53.129
- 0i 25%, :
-10.204
-4.242 14.06 32.57 44.235 46.976 0-50%o ;
-9.353
-9.482
-0.789 24.112 39.085 39.674
-8.617
- 13.627
- 16.944
-3.745 19.069 37.639
- j COD
-7.099
-17.298
-24.212
-20.265 5.15 40.319 80701 3.979 47.806 46.303 50.825 63.105 76.986 80801 4.165 40.475 46.132 54.308 68.334 76.803 80901 4.351 36.46 42.769 56.049 68.345 71.426 81001 4.537 35.844 42.789 56.287 69.758 77.424 81101 4.723 38.743 45.608 55.571 66.746 77.618 81201 4.909 44.155 47.881 52.527 61.191 71.097 Table 7: Nodal stress for 26.2° nozzle at the uphill location. The weld location is shown by the shaded row.
Hoop Stress Plot 80 60 X 40 Ca 0
0 20 0
0
-20
-40 0
1 2
3 4
Distance from Nozzle Bottom {inch}
Figure 13: Plot showing hoop stress distribution along tube axis for the 26.2° nozzle at the uphill location. The compression zone, top of blind zone and the bottom of the weld are shown.
Engineering Report M-EP-2004-001 Rev. 00 Page 22 of 54 40001 40101 40201 40301 40401 40501 0.000 0.729 1.312 1.780 2.155 2.455
-4.881
-3.137 11.237 26.997 31.378 24.259 42 AWO>tSSY;t---i
-6.344
-7.277
-8.257
-4.259
-5.323
-5.657 8.853 6.944 4.582 23.318 18.343 11.84 25.438 22.099 20.121 22.52 23.163 29.696 00
-9.768
-5.284
- 0. 547 5.76 17.774 38.662 40701 2.858 3.329 13.248 24.402 40.285 56.577 40801 3.020
-1.382 11.182 24.275 42.021 57.851 40901 3.182
-1.269 9.685 25.303 42.043 53.218 41001 3.345 0.866 11.335 25.155 39.899 54.458 41101 3.507 10.022 13.661 26.854 38.58 50.621 41201 3.670 18.215 18.191 25.804 37.533 44.945 Table 8: Nodal stress for 26.20 nozzle at the mid-plane location. The weld location is shown by the shaded row.
Hoop Stress Plot ---
ID Hoop Stress 0
p OD Hoop Stress 50 -
7%
30 Top of Blind Zone 30-Zone 0.0 0.5 1.0 1.5 2.0 2.5 3.0 Distance from Nozzle Bottom {inch}
Figure 14: Plot showing hoop stress distribution along tube axis for the 26.2° nozzle at the mid-plane location. The compression zone, top of blind zone and the bottom of the weld are shown.
C £11
Engineering Report M-EP-2004-001 Rev. 00 Page 23 of 54 1
o.000 101 0.355 201 0.640 301 0.868 401 1.051 501 1.198
':- a V:,
a
-27.262
-8.663 1.497 18.44 27.564 24.021
.~
-26.568
-3.917 3.941
- 16. 972 27.006 27.991
-25.018
-2.294 8.574 16.875 28. 041 34.116
-20.841
-3.371 6.533 13.139 24.607 49.117
-15.546
-2.704 3.174 6.557 19.607 53.8 701 1.463 17.64 25.575 39.708 801 1.610 19.157 26.134 38.392 901 1.758 21.403 25.014 37.324 1001 1.906 27.58 28.743 35.137 1101 2.054 25.638 27.624 34.486 1201 2.202 32.346 32.663 26.936 Table 9: Nodal stress for 38.50 nozzle at downhill location.
row.
56.365 55.373 51.052 66.86 77.311 66.312 47.213 67.591 37.362 41.426 27.922 21.797 The weld location is shown by the shaded Hoop Stress Plot 80 60 u
40 a) 0 20 CL 0
0
-20
-40 0.3 0.8 1.3 1.8 Distance from Nozzle Bottom {inch}
Figure 15: Plot showing hoop stress distribution along tube axis for the 38.5° nozzle at downhill location.
The compression zone, top of blind zone and the bottom of the weld are shown.
Engineering Report M-EP-2004-001 Rev. 00 Page 24 of 54 NRow 80 001 80101 80201 80301 80401 80501 0.000 1.324 2.385 3.235
- 3. 916 4.461 ID
'a
-20.713 5.79 20.088 35.237 46.802 51.852
-13.891
-0.121 19.42 33.451 45.156 48.945
-10.091
-6.365 1.112 21.848 37.936 42.423
.- 6.7 8
-6.781
-11.555
-21.708
-18.777 8.372 37.185 iigODn
-2.467
-16.261
-29.318
-33.482
-15.972 32.638 80701 80801 80901 81001 81101 81201 Table 10:
row.
5.119 55.224 51.157 55.733 5.340 53.096 55.783 60.808 5.561 50.453 53.108 62.734 5.782 48.972 52.732 63.772 6.003 48.085 53.86 65.077 6.224 50.67 55.952 62.826 Nodal stress for 38.50 nozzle the uphill location.
63.865 70.724 70.802 73.937 69.701 72.988 74.803 79.068 74.976 82.011 70.744 77.451 The weld location is shown by the shaded Hoop Stress Plot 70 Ad t
30 30
-5
£5 a.
0 0
-1 0
-50 0
1 2
3 4
5 6
Distance from Nozzle Bottom {inch}
Figure 16: Plot showing hoop stress distribution along tube axis for the 38.50 nozzle at the uphill location. The Compression zone, top of blind zone and the bottom of the weld are shown.
Engineering Report M-EP-2004-001 Rev. 00 Page 25 of 54 40001 40101 40201 40301 40401 40501 0. 000 0.846 1.524 2.067 2.502 2.851 IDS
- 10. 954 1.32 4.766 15.552
- 15. 655 4.83 25 %
4.51
-0.955 4. 123 13. 981 12. 983 8.828
- .W He 0.522
-2.652 5.007 12.901 14. 758 13. 891 575%.'N
-3.322
-3.103 4.329 10.287 16.943 24.741
-7.653
-3.549 1.791 7.177 17.57 33.61 40701 3.315
-16.1
-2.811 11.744 31.306 44.814 40801 3.500
-19.775
-4.84 10.363 31.622 44.873 40901 3.685
-18.205
-5.805 11.632 30.03 40.103 41001 3.870
-16.362
-3.949 11.963 27.256 40.737 41101 4.055
-6.523
-1.62 14.387 27.003 37.168 41201 4.240 1.577 4.361 14.559 27.38 32.59 Table 11: Nodal stress for 38.5° nozzle at the mid-plane location. The weld location is shown by the shaded row.
Hoop Stress Plot 40
_20 c)
I
-20 0
1 2
3 4
Distance from Nozzle Bottom {inch}
Figure 17: Plot showing hoop stress distribution along tube axis for the 38.50 nozzle at the mid-plane location. The top of blind zone and the bottom of the weld are shown. No compression zone exists because the ID surface has a 10.954 ksi tensile stress.
C\\-3