L-2003-067, Order (EA-03-009) Relaxation Request Examination Coverage of Reactor Pressure Vessel Head Penetration Nozzles
| ML030780589 | |
| Person / Time | |
|---|---|
| Site: | Turkey Point  |
| Issue date: | 03/11/2003 |
| From: | Jefferson W Florida Power & Light Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| EA-03-009, L-2003-067 | |
| Download: ML030780589 (11) | |
Text
0 MAR 112003 FPL L-2003-067 EA-03-09(IV)(F)(2)
U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D. C. 20555 Re: Turkey Point Unit 3 Docket No. 50-250 Order (EA-03-009) Relaxation Request Examination Coverage of Reactor Pressure Vessel Head Penetration Nozzles On February 11, 2003 the NRC issued Order (EA-03-009) requiring specific inspections of the reactor pressure vessel (RPV) head and associated penetration nozzles at pressurized water reactors. Pursuant to the procedure specified in Section IV, paragraph F of the Order, Florida Power & Light (FPL) hereby requests relaxation from the requirements specified in Section IV, paragraph C.(1 )(b)(i) for Turkey Point Unit 3 for the Reactor Vessel Head (RPVH) penetration nozzles for which ultrasonic testing requirements could not be completed as required. FPL is in the process of completing the RPVH penetration nozzle inspection, therefore, this submittal reflects results up to date. If required, FPL will submit supplemental data by March 13, 2003, upon completion of the RPVH penetration nozzle inspection.
As demonstrated in the attachment hereto, the requested relaxation meets item IV.F.(2) of the Order, as compliance with this Order for the specific nozzles would result in hardship or unusual difficulty without a compensating increase in the level of quality or safety.
FPL requests approval of the subject relaxation by March 15, 2003, the currently scheduled date for Turkey Point Unit 3 reactor re-assembly. The refueling outage completion is currently scheduled for March 19, 2003.
Please contact Walter Parker at (305) 246-6632 if there are any questions about the relaxation.
William efferson, Jr.Jr Vice President Turkey Point Plant Attachment cc: Regional Administrator, Region II, USNRC Senior Resident Inspector, USNRC, Turkey Point Plant Florida Department of Health and Rehabilitative Services an FPL Group company
L-2003-067 Attachment Page 1 of 10 TURKEY POINT UNIT 3 RELAXATION REQUEST FROM US NRC Order EA-03-009 "Hardship or Unusual Difficulty without Compensating Increase in Level of Quality or Safety"
- 1. ASME COMPONENTS AFFECTED Turkey Point (PTN) Unit 3 has 66 ASME Class 1 reactor pressure vessel (RPV) head penetrations (including the vent).
The Turkey Point Unit 3 Order Inspection Category in accordance with Section (IV.A.) is currently determined as "high" based on 18.3 EDY at this refueling outage 1 (RFO).
FPL Drawing No. 561 0-M-400-57, Sheet 1, Rev. 2 (PTN-3)
- 2. US NRC ORDER EA-03-009 APPLICABLE EXAMINATION REQUIREMENTS:
The NRC issued an Order 2 on Februay 11, 2003 establishing interim inspection requirements for reactor pressure vessel heads of pressurized water reactors.
Section IV.C. of the Order states the following :
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 (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 1 FPL letter L-2002-185, "St. Lucie Units 1 and 2, Docket Nos. 50-335, 50-389, Turkey Point Units 3 and 4, Docket Nos. 50-250 and 50-251, Response to NRC Bulletin 2002-02, Reactor Pressure Vessel Head Penetration Nozzle Inspection Programs," R. S. Kundalkar to NRC, September 11, 2002.
2 US NRC Letter EA-09-009, "Issuance Of Order Establishing Interim Inspection Requirements For Reactor Pressure Vessel Heads At Pressurized Water Reactors,", from Samuel J. Collins (NRC) to all Pressurized Water Reactor Licensees, Dated February 11, 2003.
L-2003-067 Attachment Page 2 of 10 (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.
Relaxation is requested from part IV.C.(1)(b)(i) of the Order to perform ultrasonic testing (UT) of the RPV head penetration inside the tube from 2 inches above the J-groove weld to the bottom of the penetration at Turkey Point Unit 3.
Specifically, the relaxation is related to UT examination of a limited portion of the non-pressure boundary portion of the RPV penetration nozzle greater than 1 inch below the weld to the bottom of the nozzle.
- 3. REASON FOR REQUEST:
Pursuant to Order Section IV.F.(2) "Compliance with the Order for specific nozzles would result in hardship or unusual difficulty, without a compensating increase in the level of quality and safety", FPL is requesting this relaxation for Turkey Point Unit 3. Currently, with 48 of 66 RPV nozzle penetrations examined, there are 6 RPV head penetrations that contain areas of coverage less than that required by the NRC Order. The Order requires examination from 2 inches above the J-groove weld to the bottom of the RPV head penetration nozzle. The reduced coverage is caused by nozzle configuration, and limitations of the probe design used for the Ultrasonic (UT) examination. Specifically, actual coverage below the weld, in the non-pressure boundary portion of the nozzle, did not in all cases, extend to the "bottom of the nozzle." A typical example of the UT cover area, with the area of missed coverage identified, is shown in Figure 1.
L-2003-067 Attachment Page 3 of 10 Figure 1: Typical RPV Nozzle UT Inspection "C" Scan with area of missed coverage identified by arrows and above the white horizontal line.
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L-2003-067 Attachment Page 4 of 10
- 4. PROPOSED ALTERNATIVE AND BASIS FOR USE:
The proposed alternative is to perform the UT examination to the extent practical.
This is defined as "the examination shall be performed to include 2 inches above the weld to_> 1 inch below the weld." This relaxation request documents and submits to the NRC, deviations from the NRC Order required inspection coverage area along with a justification as to their acceptability.
BASIS FOR RELAXATION:
Additional efforts to achieve the Order required examination area (below the weld) will result in a hardship due to unusual difficulty without a compensating increase in the level of quality and safety.
The scope of the examination was to perform a 3600 volumetric examination from 2 inches above the J-groove weld down to the bottom of the RPV penetration nozzles. The 66 Turkey Point Unit 3 RPV penetration nozzles are used for a variety of functions and present a variety of examination conditions. The 45 RPV penetration nozzles that are attached to active control rod drive mechanisms (CRDMs) have funnel-ended guide sleeves permanently attached inside the nozzles leaving only a narrow annulus available for inspection. The 6 RPV penetration nozzles attached to part length CRDMs have the threaded guide sleeve permanently retracted and pinned inside the RPV penetration nozzles.
The two RPV penetration nozzles modified for the reactor vessel level measurement system (RVLMS) have a guide sleeve installed along with a welded end plate (that required removal for inspection). The other 13 RPV penetration nozzles (8 spares, 4 instrument penetrations, and 1 small bore vent line) are open once the RPV head is removed from the vessel for inspection and require a special centering adapter (except the vent) for scanning with the current UT equipment. These various design conditions, and the normal distortion of the RPV penetration nozzles caused by the welding into the sloped hemispherical head, result in a variety of examination conditions. The UT probes are optimized for these examination conditions, however, not all the conditions can be anticipated. The UT examination technology currently available for the Turkey Point Unit 3 RPV penetration nozzle inspections, has resulted in some areas of missed inspection > 1 inch below the weld. A hardship or unusual difficulty, without a compensating increase in level of quality or safety, would result if physical modifications, such as removal of RPV nozzle penetration sleeves or new UT equipment would have to be developed, to achieve the complete coverage in the non pressure boundary portion of the RPV nozzle material > 1 inch below the weld required by the Order.
To evaluate the significance of the lack of UT inspection coverage, the inspection coverage data was broken into 2 distinct regions. Those regions include the
L-2003-067 Attachment Page 5 of 10 nozzle base material from 2 inches above the weld to a minimum of 1 inch below the weld, and from > 1 inch below the weld. A summary of these 2 UT coverage areas, and the number of nozzles affected as of March 11, 2003 is provided in Table 1 below. When the remaining 18 penetrations are inspected, evaluated, and the RPV nozzle penetration UT inspection is complete, FPL will supplement this relaxation, if required, by updating Tables 1 and 2 with the final total of nozzles that meet the criteria described above. If examination of any of the remaining nozzles does not meet the criteria identified in the proposed alternative and basis for use in Section 4 above, that nozzle would not be covered under this relaxation request.
Table 1: Summary of Complete and Incomplete Inspection Coverage Area of UT Coverage Number of Penetrations Inspected Complete coverage from 2" above 48 of 48 completed (18 additional the weld to a minimum of 1" below penetrations to be inspected) the weld Complete coverage from 1" below 42 of 48 the weld to the bottom of the nozzle Incomplete coverage from 1" below 6 of 48 the weld to the bottom of the nozzle A complete matrix of the UT inspection coverage areas, UT inspection results and the "leak path" results is provided in Table 2.
L-2003-067 Attachment Page 6 of 10 Table 2: Turkey Point Unit 3 UT Data Coverage Matrix for RPV Nozzles RPV Turkey Point Unit 3 Cycle 20 - Extent of UT Coverage in RPV Leak Path Data Nozzle Material Pen # Min. Coverage Coverage Weld Below Min Distance Comments Determination Leak Path Distance Above @ Weld Region Weld Below Weld Possible? Results Above Weld Root Root Coverage Coverage Toe when Weld (Theta) (Theta) (Theta) (Theta) Incomplete Root coverage (Inches) (Inches) 1 3.10 360 360 360 360 N/A NRI (No Recordable Yes No Leak Indications) Path (LP) 2 3 3.24 360 360 360 360 N/A NRI Yes No LP 4
5 6
7 8 3.22 360 360 360 360 N/A NRI Yes No LP 9 3.34 360 360 360 360 N/A NRI Yes No LP 10 11 12 13 14 3.00 360 360 360 360 N/A NRI Yes No LP 15 3.22 360 360 360 360 N/A NRI Yes No LP 16 3.13 360 360 360 360 1.4 NRI, coverage below Yes No LP weld from 121° - 78'.
17 3.19 360 360 360 360 N/A NRI Yes No LP 18 3.30 360 360 360 360 N/A NRI Yes No LP 19 3.33 360 360 360 360 N/A NRI Yes No LP 20 21 22 3.00 360 360 360 360 N/A \IRI Yes No LP 23 24 25 3.23 360 360 360 360 N/A 14RI Yes No LP 26 2.60 360 360 360 360 N/A F4RI Yes No LP 27 2.60 360 360 360 360 N/A NRI Yes No LP 28 3.14 360 360 360 360 N/A NRI Yes No LP 29 2.89 360 360 360 360 N/A NRI Yes No LP 30 3.29 360 360 360 360 N/A NRI Yes No LP 31 3.10 360 360 360 360 1.1 'IRI, coverage below Yes No LP
__eld from 303° - 3600.
32 33 2.90 360 360 360 360 N/A NRI Yes No LP 34 3.13 360 360 360 360 N/A IRI Yes No LP 35 3.10 360 360 360 360 N/A IRI Yes No LP 36 3.55 360 360 360 360 N/A IRI Yes No LP
L-2003-067 Attachment Page 7 of 10 37 38 3.30 360 360 360 360 N/A RI Yes No LP 39 2.68 360 360 360 360 N/A NRI Yes No LP 40 2.80 360 360 360 360 N/A IRI Yes No LP 41 2.80 360 360 360 360 N/A IRI Yes No LP 42 2.17 360 360 360 360 N/A NRI Yes No LP 43 2.87 360 360 360 360 1.0 NRI, coverage below Yes No LP meld from 3280 - 104'.
44 2.90 360 360 360 360 N/A 'IRI Yes No LP 45 3.00 360 360 360 360 N/A 'IRI Yes No LP 46 2.10 360 360 360 360 N/A 'IRI Yes No LP 47 2.00 360 360 360 360 N/A 14RI Yes No LP 48 49 2.30 360 360 360 360 N/A IRI Yes No LP 51 2.45 360 360 360 360 N/A RI Yes No LP 53 2.30 360 360 360 360 N/A RI Yes No LP 55 2.24 360 360 360 360 N/A RI Yes No LP 57 2.30 360 360 360 360 N/A RI Yes No LP 58 3.30 360 360 360 360 N/A RI Yes No LP 59 60 61 4.00 360 360 360 360 N/A IRI Yes No LP 62 3.60 360 360 360 360 N/A 14RI Yes No LP 63 2.00 360 360 360 360 1.8 'IRI, coverage below Yes No LP weld from 3220 - 3550.
64 2.38 360 360 360 360 1.5 NRI, coverage below Yes No LP
__eld from 3180 - 49.4°.
65 2.68 360 360 360 360 N/A 'IRI Yes No LP 66 3.00 360 360 360 360 N/A NRI Yes No LP 67 2.98 360 360 360 360 1.9 NRI, coverage below Yes No LP meld from 343_ - 170°.
68 3.17 360 360 360 360 N/A NRI Yes No LP 69 2.69 360 360 360 360 N/A NRI Yes No LP Vent 2.00 360 360 360 N/A N/A NRI N/A N/A To determine the significance of the lack of UT examination coverage, the effect of a postulated axial and circumferential flaw in the nozzle material was evaluated relative to the areas of examination coverage identified above.
From 2 inches above the weld to 1 inch below the weld: The areas of prime interest because of the safety concern for nozzle ejection and LOCA are circumferential cracks located in the nozzle material at the weld root and above the weld. This is also the area that axial cracks would have to propagate to in order for a leak to occur through the RPV penetration nozzle material. The UT examinations of the RPV penetration nozzles have bounded this area (the safety significant region), by providing complete 3600 coverage of the nozzle base material (from 2 inches above the weld to 1 inch below the weld) for all the RPV
L-2003-067 Attachment Page 8 of 10 nozzle penetrations currently inspected. Therefore, reliable assurance is provided to conclude that safety significant circumferential flaws do not exist at or above the weld root.
Greater than 1 inch below the weld to the bottom of the nozzle: Axial flaws in the area of non-coverage in the non-pressure boundary nozzle base material below the weld are of no structural significance, however, a postulated flaw could grow above the weld to the point of leakage followed by wastage and/or potential initiation of an OD circumferential flaw.
To determine the significance of an axial flaw that is contained in the non pressure boundary nozzle material in the un-inspected region >1 inch below the weld, a flaw tolerance approach is used. A flaw evaluation was performed postulating an axial flaw in the area of missed coverage below the weld using WCAP-1 6027-P 3. A through wall flaw is postulated in the nozzle material from the bottom of the penetration to 1" from the bottom of the weld. The flaw evaluation in WCAP-1 6027-P is based on Turkey Point Unit 3 and 4 specific stresses in the nozzle penetrations. Since the stresses >1" below the weld are too low to propagate an axial flaw, the WCAP-1 6027-P flaw evaluations start at 1/2" below the weld, and evaluate the time to propagate the flaw in the nozzle to the bottom of the weld (start of the pressure boundary portion of the nozzle material or toe of the J-groove weld). Assuming a through wall flaw below the weld, with the flaw end located at 1/2" below the weld (which is in the area of complete UT examination coverage), an axial flaw would take greater than 5 years of operation (Figures 6-12 through 6-20 in WCAP-16027-P) in any nozzle location to grow to the point of contact with the weld. This time period is significantly greater than the current inspection frequency of every refueling cycle (18 months for Turkey Point Unit 3) identified in NRC Order EA-03-009. As an added conservatism, this evaluation does not attempt to evaluate the time for the axial flaw to grow from the bottom of the weld through the pressure boundary.
Figure 2 provides a graphical presentation of the above flaw evaluation discussion for the outer most penetration location.
3 "Structural Integrity Evaluation of Reactor Vessel Upper Head Penetrations to Support Continued Operation:
Turkey Point Units 3 & 4," Westinghouse Electric Co. LLC, WCAP-16027-P Revision 0, Draft, February 2003.
L-2003-067 Attachment Page 9 of 10 11.5 11.0
.E 10.5 E
0
_* 10.0 0
0 z
E o 9.5 9.0 8.5 8.0 7.5 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Period (Year)
Figure 2: Through-Wall Axial Flaws Located in the 42.6 Degree Row of Penetrations, Uphill Side - Crack Growth Predictions (From Figure 6-19, WCAP 16027-P)
Therefore, there are no concerns with the structural integrity of the RPV penetration nozzles that could be caused by axial cracking in the missed coverage areas in the non-pressure boundary portion of the nozzle material > 1" below the weld for a period of > 5 years of operation.
This conclusion is based on the following results:
"* UT inspection results of no indications in the nozzle areas examined from a minimum of 1" below the weld to 2" above the weld (100% coverage obtained)
"* Acceptable assessment of no "leak path" present into interference fit zone (100% coverage obtained)
"* UT inspection results of no indications in the nozzle areas examined greater than 1" below the weld (coverage per Table 2)
L-2003-067 Attachment Page 10 of 10 Acceptable bare metal visual examination results of no leakage or wastage of the RPV head
- 5. DURATION OF PROPOSED ALTERNATIVE:
This relaxation is applicable to the March 2003 refueling outage for PTN-3. After one operating cycle from the 2003 identified refueling outage, the PTN-3 RPV head will be re-inspected as per the Order, or the RPV head will be replaced.