ML20141D243
| ML20141D243 | |
| Person / Time | |
|---|---|
| Site: | Quad Cities  |
| Issue date: | 09/30/1985 |
| From: | SCIENCE APPLICATIONS INTERNATIONAL CORP. (FORMERLY |
| To: | |
| Shared Package | |
| ML20141D217 | List: |
| References | |
| CON-NRC-03-82-096, CON-NRC-3-82-96 SAIC-84-1655, NUDOCS 8604070457 | |
| Download: ML20141D243 (34) | |
Text
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Report No. SAIC-84/1655 ATTACHMEllT
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TECHNICAL EVALUATION REPORT SECOND INTERVAL INSERVICE INSPECTION PROGRAM QUAD CITIES NUCLEAR POWER STATION, UNITS 1 AND 2
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Submitted to
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U.S. M1 clear Regulatory Commission Contract No. EC-03-82-096 i
Submitted by G
Science Applications International Corporation Idaho Falls, Idaho 83402
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September 1985
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CONTENTS
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I N TRO D U CT I O N.............................
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I. CLASS I CQiPONENTS 3
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A.
Reactor Vessel 1.
Relief Request CR-1, Reactor Vessel Shell Welds, Category B-A, Items B1.11 and 81.12..........
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Relief Request CR-2, Reactor Vessel Bottom Head
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Wel ds, Category B-A, Items Bl.2i and Bl.22....... 6 3.
Relief Request CR-11, Standby Liquid Control Nozzle, Category B-D, Item B3.100 8
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B.
Pressurizer ( Nat applicable to BWRs)
C.
Heat Exchangers (No Class 1 relief requests)
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D.
Piping Pressure Boundary 10 1.
Relief Request 01-3, Control Rod Drive and Residual Heat Removal (RHR) System Welds, Category B-J, Item B9.11 10 (a
2.
Relief Request CR-4, Piping Welds in Containment Penetrations, Category B-J, Item B9.ll.......
17.
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Relief Request CR-5, Piping System Branch Connection Wel ds, Category B-J, Item B9.31....... 15
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E.
Pump Pressure Boundaries 1.
Relief Request CR-6, Recirculation Pump Casing Examinations, Ca tegory B-L-2, Iten B12.20 17
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Val v e P res s u re Bo un da ri es..................
19 1.
Relief Request CR-7, Internal Surfaces of Valves, j
Category B44-2, Item B12.40 19 l
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I I. C LAS S 2 COM PO NE NTS.......................
21 A.
Pressure Vessels and Heat Exchangers 21 l.
Relief Request CR-8, Residual Heat Removal Heat Exchanger Nozzle-to-Shell Welds, Nozzle-to-Shell Welds, Category C-B, Items C2.21 and C2.22 21
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Piping 1.
Relief Request CR-10, Piping System Branch Connection Welds, Category C-F, Item C5.31......
23 C.
Pumps (No relief requests)
D.
Valves (hb relief requests)
III. CLASS 3 00iPONENTS ( No relief requests)
IV. PRESSURE TESTS A.
Class 1 Pressure Tests (No relief requests)
B.
Class 2 Pressure Tests 26 1.
Relief Request CR-12, hydrostatic Testing of the High Pressure Coolant Injection Turbine, Ca te go ry C-H.....................
26 28 V.
GENERAL............................
A.
Ul trasonic Examination Techniques.............
28 le 1.
Relief Request CR-9, Calibration Block I'
Documen ta tion 28 i
31 j
REFERENCES.............................
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t' TECHNICAL EVALUATION REPORT SECOND INTERVAL INSERVICE INSPECTION PROGRAM
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Quad Cities Nuclear Power Station, Units 1 and 2 4
INTRODUCTION This report evaluates requests for relief from certain examination and pressure test requirements of Section XI of the American Society of Mechani-cal Engineers ( ASME) Boiler and Pressure Vessel Code
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Commonwealth Edison Company (Cfr.0), of the Quad Cities Nuclear Power Station, Units 1 and 2.
The relief requests cover the second 120-month inspection intervals starting February 18, 1983, for Unit 1 and March 10, 1983, for Unit 2.
The requests are based upon the 1980 Edition of Section XI, with Addenda through Winter 1980, as specified in the applicable revision of 10 CFR 50.55a.
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The rest of this introduction summarizes (a) the scope of this report, (b) the previous review of rp lef requests by Science Applications Inter-national Corporaticn (SAIC),L 1 an the history of Quad Cities relief requests since the earlier review.f2
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The current revision to 10 CFR 50.55a requires that Inservice Inspection (ISI) programs be updated each 120 months to meet the require-ments of newer editions of Section XI.
Specifically, each program is to meet the requirements (to the extent practical) of the edition and addenda of the Code incorporated in the regulation by reference in paragraph (b) 12 months before the start of the current 120-month interval.
0 The regulation recognizes that the requirements of the later editions and addenda of the Code might not be practical to implement at facilities because of limitations due to design, geometry, and materials of construction of components and systems.
Therefore, the regulation permits exceptions to impractical examination or testing requirements to be evaluated. Relief
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from the,e requirements can be granted, provided the health and safety of the public are not endangered, giving due consideration to the burden placed on the licensee if the requirements were imposed.
This report only l
evaluates requests for relief dealing with inservice examinations of components and with system pressure tests.
Inservice test programs for pumps and valves (IST programs) are being evaluated separately.
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- Hereinafter referred to asSection XI or Code.
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f' The current revision of the regulation also provides that ISI programs may meet the requirements of subsequent Code editions and addenda, incor-porated by reference in paragraph (b) and subject to Nuclear Regulatory r
Commission (NRC) approval.
Portions of such editions or addenda may be used, provided that all related requirements of the respective editions or addenda are met. These instances are addressed on a case-by-case basis in the body of this report.
Finally,Section XI of the Code provides for certain components and
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systems to be exempted from its requirements.
In some instances, these exemptions are not acceptable to the NRC or are only acceptable with restrictions.
As appropriate, these instances are also discussed in this report. Unless otherwise noted, all items in this report pertain to both Quad Cities units.
I In its previous Technical Evaluation Report dated September 17, 1982, SAIC(I) evaluated relief requests for Quad Cities covering the last 40 months of the first inspection interval (October 18, 1979, to February 18, 1983, for Unit 1 and November 10, 1979, to March 10, 1983, for Unit 2).
These requests were based on the 1974 Edition with addenda through Summer 1975, the applicable Code in effect at the time. SAIC's report was 7
incorporptqd into NRC's Safety Evaluation Report on the First Interval Program,t2s issued May 19, 1983.
17,1983.(iqcond interval, including relief requests, wasIn Apri The ISI program for the JJ submitted February The additional information to complete the review of the relief reques )
p information was furnished as an attachment to a September 7,1984, letter. This letter also contained a revision of one relief request submit-ted in Reference 3 and two additippg1 relief requests.
On January 9,1985, a revised second interval programm was submitted.
This revision incor-porated some of the information given in the letter of September 7, 1984(4) and withdrew one relief request (CSR-1).
A second request for additional before the revised program was received.(ogram was sent on Janu g'
information based on the initial second interval pr 61 In response to the 11, 1985, request and a subsequent telephone conversati n the licensee provided four 9
revised relief requests on February 27,1985.L 7I This response also submit-ted a new first interval request, which is being evaluated in an addendum to SAIC's first interval Technical Evaluation Report.
p As a result of the above submittals,12 relief requests (CR-1 thrcugh CR-12) have been identified as requiring disposition. These requests are evaluated in the following sections of this report.
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f I. CLASS 1 COMPONENTS A.
Reactor Vessel 1.
Relief Request CR-1, Reactor Vessel Shell Welds, Category B-A,
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Items Bl.ll and Bl.12 Code Requirement One circumferential and one longitudinal beltline region weld I
shall be volumetrically examined in accordance with Figure IWB-2500-1 and -2 once each interval. For each weld, the examination shall include essentially 1007, of weld length.
The selected welds shall be located at design structural discontinuities, if any, and be reexamined during successive intervals.
Examinations may be performed at or near the end of the inteival.
Code Relief Daquest Relief is requested from examining the beltline region welds in the reactor vessels.
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Proposed Alternative Examination One longitudinal beltline region shell weld has a l'ength of 11'1", hence,11'1" of accessible longitudinal shell weld in the
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upper shell area will be examined in order to achieve an examination sample equivalent to the Category B-A longitudinal weld for which relief is requested. There are no accessible cir-cumferential welds in the u'pper shell area, therefore no increased examination is f easible. Commonwealth Edison originally committed to keeping abreast of improvements in state-of-the-art nondestruc-
.D tive examination (NCE) techniques that could provide a viable means of examination.
The station's procedure is to be revised to insure the performance of the alternative examinations.
Licensee's Basis for Requesting Relief
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Currently, it is not feasible to perfonn the required volu-metric examinations on these welds. Accessibility for inspection of *.hese welds was not provided for in the original plant design whi:h occurred prior to the issuance of Section XI inservice inst ?ction requirements.
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Examination from the reactor vessel outer surface is pre-clused due to the ci3ca proximity to the biological shield wall and obstruction by the vessel insulation. The mirror type insulation consists of interlocking panels which were not designed to be easily removable at the weld locations. Furthermore, the
.I annular dimensions between the shield wall and the insulation are 3
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not sufficient to allow direct access to personnel. Access through the biological shield wall is only provided at reactor vessel nozzle locations; however, there are no nozzle penetrations in the bel tline region.
Examination of the beltline region welds from inside the vessel is impeded by vessel internal design features.
The core shroud, jet pumps, and various brackets welded to the vessel wall are not designed to be removable.
E Evaluation As shown in a sketch accompanying the licensee's submittal, the reactor vessel contains four shell courses, labeled #1 to #4, I
between the bottom head and the vessel flange.
Each course con-tains three longitudinal welds. These welds in shell courses #1 and #2, as well as the circumferential weld connecting these two courses, are beltline welds and inaccessible.
Portions of the concrete biological shield and the I
permanently installed insulation would have to be removed to perform the required examination of the welds from the vessel exterior.
The vessel internals, shroud, and jet pumps preclude volumetric examination of almost all the beltline weld volume from the vessel interior. Hence, imposition of Code requirements would be impractical.
The vessel was designed and fabricatedI8) to the rules of Section III of the Code (1965 Edition).
Ongoing efforts to ensure vessel integrity include:
o Material surveillance and operation in accordance with
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Code-required volumetric examinations of other welds on the vessel, including closure head welds, head-to-flange weld, and vessel-to-flange weld.
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Periodic hydrostatic pressure testing to IWA-5000.
The licensee has committed to fully examining an equivalent length of longitudinal weld in the three accessible longitudinal lC welds in the uppermost shell course (#4).
The licensee has also l
committed to considering improvements in state-of-the-art M)E techniques as they become available. These alternative actions in conjunction with the described surveillance and pressure tests j
should be accepted in lieu of Code required volumetric examinations.
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Conclusions and Recommendations Based on the above evaluation, it is concluded that.for the I
welds discussed above, the Code requirements are impractical.
It is further concluded that the alternative examinations discussed in the evaluation will provide necessary added assurance of structural reliability.
Therefore, it is recommended that relief be granted from the volumetric examination of die identified welds with the following provisions:
(a) An equivalent length of longitudinal weld in the uppermost shell course should be 100% Code examined in place of die longitudinal beltline welds, as proposed.
(b) The licensee should, as originally proposed, keep abreast of f
improvements in sta te-of-the-art NDE techniques.
If a means becomes available for examining the Code-required bel tline welds, these welds should be examined in lieu of the examina-tions in (a) above.
C References References 3, 5, and 8.
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Relief Request CR-2, Reactor Vessel Bottom Head Welds, Category B-A, Items B1.21 and Bl.22
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Code Requirement One circumferential and one meridional weld are to be volu-metrica11y examined in accordance with figure IWB-2500-3 once during each inspection interval.
For each weld, the extent of I
examination includes the accessible portion up to 100% of weld length. The bottom head welds may be examined at or near the end of the interval.
Code Relief Request r
Relief is requested from the Code requirements to examine the bottom head welds of the reactor vessel.
Proposed Alternative Examination i
Currently, it is not feasible to perform the required volumetric examinations on the bottom head welds. Commonweal th Edison will, however, keep abreast of improvements in state-of-the-art NDE techniques that could provide a viable means of examination.
P Licensee's Basis for Requesting Relief Accessibility for examination of these welds was not considered in the plant design. The bottom head welds cannot be examined because of the limited physical access, the inability to remove vessel insulation panels, and also because of interference from the forest of control rod drive and instrumentation penetra-tions.
Augmented examinations nay not be necessary because Section XI of ASME Code,1980 Edition through Winter 1980 Addenda, only requires examination of accessible welds.
5 Evaluation The code specifies that only the accessible lengths of one circumferential and one meridional head weld are to be volu-
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metrica11y examined in this interval. All pressure retaining welds in the bottom head are inaccessible to Code examinations, and so technically, relief from the Code is not required.
Even though the Code acknowledges that accessibility may be limited with respect to volumetric examination of head welds, the
't intent of the Code is clearly to encourage some volumetric exami-nation of the welds. The licensee is committed to considering C
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a-improvements in state-of-the-art WE techniques as they become avail able.
Accordingly, it would be appropriate to grant relief G
to ensure that the licensee will continue to look for methods that make these welds accessible for examination.
The licensee has also committed to fully examining a length of accessible longitudinal welds in the uppermost shell course (see I. A.1 of this report).
This commitment should be accepted as g
a provision of this relief request.
Conclusions and Recommendations Based on the above evaluation, it is concluded that for the g-bottom head circumferential and meridional welds, the Code re-quirements are impractical.
It is further concluded that the alternative examination discussed in the evaluation will provide necessary added assurance of structural reliability. Therefore, it is recommended that relief be granted from the Code-required volu-metric examinations of the bottom head meridional and circumfer-g ential welds, with the following provisions:
(a) A length of longitudinal welds in the uppermost shell course should be 100% Code examined, as proposed.
g (b) The licensee should, as proposed, keep abreast of improve-ments in state-of-the-art NDE techniques.
If a means becomes available for examining the Code-required bottom head welds, their examination should be scheduled.
b Re ferences Referersces 3, 4, and 5.
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t-3.
Relief Request CR-11, Standby Liquid Control Nozzle, Category B-D, Item B3.100
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Code Requirement The inside radius sections of all reactor vessel full penetration nozzles are to be volumetrically examined in accor-g dance with Figure IWB-2500-7(a) through (d) each interval. At least 25% but not more than 50% (credited) of the nozzles shall be examined by the end of the first inspection period and the remainder by the end of the third inspection period of each inspection interval.
If examinations are conducted from inside the component and the nozzle weld is examined by straight beam p.
ultrasonic method from the nozzle bore, the remaining examinations required to be conducted from the shell may be performed at or near the end of each inspection interval.
Code Relief Request 7
Relief is requested from examining the inside radius section of the standby liquid control (SBLC) nozzle.
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Proposed Alternative Examinations No alternate or augmented examinations are feasible at this time.
Licensee's Basis for Requesting Relief g
The design of the SBLC nozzle piece does not lend itself to ultrasonic inspection.
The nozzle has an integral socket to which the boron injection piping is fillet-welded and consequently pro-vides a sharp-edged radius that will result in a meaningless ultrasonic examination.
7 Evaluation Because of the sharp-edged geometry of the SBLC nozzle opening, the radius is essentially zero. This geometry returns I
poor ultrasonic testing (UT) results. Therefore, UT is not practical to perform.
Adequate information on the nozzle's integrity should be provided by the required nozzle-to-vessel weld examination that the licensee intends to perform as a part of the ISI program.
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Conclusions and Recommendations 7
Based on the above evaluation, it is concluded that, for the standby liquid control nozzle, examining the inside radius section is impractical.
It is further concluded that the Code-required cozzle-to-vessel weld examination will provide necessary assurance of structural integrity. Therefore, relief should be granted as 3
requested.
References
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Reference 4 and 5.
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Pressurizer, Not applicable to BWRs.
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Heat Exchangers
% Class 1 relief requests.
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Piping Pressure Boundary 1.
Relief Request CR-3, Control Rod Drive and Residual-Heat Removal (RM) System Welds, Category B-J, Item B9.11 (Item B4.5 in 1974 575) 4
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Code Requirement The licensee has elected to use the 1974 Edition of the Code, Summer 1975 Addenda to determine the extent of piping examinations under Category B-J.
This Code requires that examinations be per-(
formed on all the area of 25% of the circumferential joints (including the adjoining 1-f t sections of longitudinal welds) each interval.
A dif ferent 25% sample is required in successive inter-val s. The 1980 W80 Code requires that, for circumferential. welds in pipe of nominal pipe size 4 in, and greater, surface plus volumetric examinations be performed in accordance with Figure
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Code Relief Request Relief is requested from the examination requirements on three
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welds in Unit 2 (03-F11, 03-S18, and 10H3-F7) and two welds in Unit 1 (03-S17 and 10HS-S8) that are in the control rod drive (CRD) system (Line 0308-4") and residual heat removal (RHR) system (Line 1011-4").
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Proposed Al ternative Examination No alternate or augmented examinations are feasible or necessary in this case because of inaccessibility.
The examina-tions required by IWB-5000 will, however, be conducted in accordance with the Code.
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Licensee's Basis for Requesting Relief Three welds in Unit 2 and two welds in Unit 1 are physically inaccessible to examination.
These welds are in the CRD System
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(Line 0308-4") and in the RHR System ( Line 1011-4").
The CRD System welds cannot be examined because of structural support lC 10 WD
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in ter ference. The RHR weld in each plant is located just above the reactor cavity and drywell and is inaccessible due to the presence of a water barrier and sleeve arrangement. The implications of f
this exenption are mininal due to the fact that safety margins inherent in the design of the subject welds are typical of those in all other welds in the Class 1 systems.
Exempting these welds from the total inspection sampling program will have negligible statis-tical significance.
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Evaluation The subject welds are inaccessible because of interference from support structures.
The number of welds involved is san 11 in
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relation to the total number of welds in these systems.
Al so, i f it is assumed that the workmanship and quality assurance of the welding were adequate, then examining other welds in this system should reflect their overall material condition.
The Code being used requires that the licensee pick different welds to examine each interval. Therefore, relief will be needed for the subject f
welds, although the licensee should attempt to maintain the required 25% sample size this interval for these systems.
- Also, visual examinations coincident with the required IWB-5000 pressure testing should be performed, which would provide initial evidence of seepage from a through-wall perforation.
C Conclusions and Recommendations Based on the above evaluation, it is concluded that for the welds discussed above, the Code requirements are impractical.
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Therefore, relief should be granted from the volumetric exami-nation of the identified welds with the following provisions:
(a) The Code-required 25% sample size should be maintained, if practical, for examining the other welds in the RHR and CRD systems.
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(b) Visual examinations should be performed on the inacces-sible welds when leakage and hydrostatic tests are conducted in accordance with IWB-5000.
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Re ferences References 3, 4, 5, and 7.
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Relief Request CR-4, Piping W31ds in Containment Penetrations, Category B-J, Item B9.11 (Item B4.5 in 1974 S75)
I Code Requirement The licensee has elected to use the 1974 Edition of the Code, Summer 1975 Addenda to determine the extent of piping examinations under Category B-J.
This Code requires that examinations be performed on all the area of 25% of the circumferential joints (including the adjoining 1-ft sections of longitudinal welds) each interval.
A different 25% sample is required in successive inter-val s.
The 1980 W80 Code requires that, for circumferential welds in pipe of nominal pipe size 4 in, and greater, surface plus volumetric examinations be performed in accordance with Figure IWB-2500-8.
Code Re1ief Request Relief is requested frcm the Code-required examinations of one circumferential weld in each penetration in de following lines:
CRD RETURN - 0308-4" RfR - 1012A and B-16",1025-20",1011-4" Rx WATER CLEARJP - 1202-6" CORE SPRAY - 1403-10", 1404-10" HPCI - 2305-10" MAIN STEAM - 3001 A, B, C, D-20" a-FEEDWATER - 3204A and B-18".
Proposed Al ternative Examination I
The examinations required by IWB-5000 will be conducted in accordance with the Code.
The first pressure boundary weld outside the containment on each of these process pipes will be l
volumetrically examined, where practical, over 100% of its length during each inspection interval. The station's procedure is to be revised to insure performance of the alternative examinations.
Licensee's Basis for Requesting Relief Each of the lines listed above penetrates the primary con-tainment by means of a penetration assertly whose design leaves one circumferential pressure-retaining weld that is inaccessible for 3
volumetric examination.
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As stated in 10 CFR 50.55a(g)(1), for plants whose construc-tion permits were issued prior to January 1,1971, components shall meet Section XI requirements to the extent practical. Since examination requirements for these welds did not exist at the time
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Quad Cities Station was designed, ac'cessibility for their examina-tion was not a prime consideration. The location of the subject welds makes it extremely impractical to examine then by volumetric or surface techniques. Commonwealth Edison feels that this constitutes a basis for relief from the volumetric examination requirements of Section XI.
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.The safety implications of these exemptions are minimal due to the fact that the safety margins in the subject welds are typical of those in all walds in the applicable systems. Since the exempted welds represent only a small fraction of the total number of circumferential, Category B-J welds in these systems (15
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out of 435, and 15 out of 476 in Units 1 and 2. respectively), the statistical significance to the inspection sampling program due to exempting these welds is expected to be negligible.
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Evaluation The number of welds involved is small in relation to the total nurber of welds in these sys tems.
Also, if it is assumed that the workmanship and quality asturante of the welding were adequate, then examining other velds in these lines should reflect their overall materia'l condition. The Code being used requires t'
that the lic.ensee choose different elds to examine each interval.
Therefore. relief will be needed for the subject welds, although the licensee should attempt to mairitain the required 25% sampic size this interval.
In response to a request for additional information, the
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licensee agreed that the first pressure boundary weld outside the containment on each of the process pipes would be volumetrically examined, where pra,:tical, over 100% of its length during each inspection interval. This alternative examination is consistent with that performed during the first inspection interval and is
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acceptable.
Also, visual examinations coincident with IWB-5000 l
pressure testing (which would provide initial evidence of seepage from a through-wall perforation) should be performed as proposed.
!g Conclusions and Recommendations Based on the above evaluation, it is concluded that for the welds discussed above, the Code requirements are impractical.
It is further concluded that the alternative examination discussed above will provide necessary added assurance of structural reli-abil ity. Therefore, relief should be granted from the volumetric
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examinations of the identified welds with the following provisions:
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(a) The first pressure boundary weld outside the containnent on each of the precess pipes shculd be volumetric 411y examined, where prectical, over 100% of its length during each interval.
P (b) The Code required 25% sample size should be maintained, if practical, for examining the other welds in the sys tem.
N (c) Visual examinations should be performed on the contain-ment penetration assemblies when leakage and hydrostatic tests are conducted in accordance with IWB-5000.
f Re ferences References 3, 4, 5, and 7.
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Relief Requests CR-5, Piping System Branch Connection Welds, Category 8-J, Item B9.31 (Items B4.6 and B4J in 1974 575)
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Code Requirement The licensee has elected to use the 1974 Edition of the Code, Summer 1975 Addenda to determine the extent of piping examinations under Category B-J.
Thr-exarr.inations performed during each inspec-I tion interval shall cover all the area of 25% of the pipe branch connection joints.
This Code requires that a different 25% sample be examined in successive intervals.
The 1980 W80 Code requires that, for welds in branch connections greater than 4 in., surface plus volumetric examinations be performed in accordance with Figures IWB-2500-9, -10, and -11.
, Code Relief Request Relief is requested from examining four Class 1 branch-to-pipe wel ds.
Proposed Al ternative Examination A visual examination of these joints for evidence of leakage will be conducted during the pressure tests required by IWB-5000.
Also, the saddle fillet welds will be surface examined to the extent required by the Code.
The station's procedure will be revised to insure that the alternative examinations are performed.
Licensee's Basis for Requesting Relief
,a The design of certain Class 1 branch pipe connection welds calls for the use of reinforcement saddles.
These saddles are fillet-welded over the actual pressure-retaining branch
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pipe-to-main pipe welds, completely encasing them.
A The fabrication of these joints precludes any type of surface e'xamination or meaningful volumetric examination of the pressure-i retaining welds.
Additional assurance of the continued integrity of joints fabricated in this fashion is afforded by the fact that the reinforcement saddle strengthens the joint and reduces the stresses on the internal weld.
b holes.u 8) reinforcement saddles were fabricated with drilled ven T )e These holes provide a means to determine if the ob-l structed pressure-retaining weld has developed any through-wall de fect.
This vent hole will be observed during the required t
Section XI, IWB-5000 tests.
Commonweal th Edison Company feels that 8
this inspection program provides for adequate margins of safety in the subject branch connections.
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s Evaluation The reinforcing saddles covering these branch connection welds prevent tne performance of Code examinations.
The number of f
welds needing relief is low, and a significant portion of each system will be Code examined.
For Class 2 nozzles, the 1980 Edition (Winter 1981 addench) of the Code recognizes that the reinforced design exists and has in those cases specified that the saddle-to-pipe welds, rather f
than the pressure-retaining welds, be surface examined.
It would be appropriate, therefore, to extend this philosophy te similar designs in Class 1 branch connections.
Hence, a reasonable alternative program to that required by the Code would be to surface examine all applicable saddle-to-(
pipe fillet welds. The licensee should also do the proposed visual VT-2 examination during pressure tests, which would provide initial evidence of seepage from a through-wall perforation.
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Conclusions and Recommendations Based upon the above evaluation, it is concluded that for the welds discussed above, the Code requirements are impractical.
It is further concluded that the siternative surface and visual examinations discussed will provide necessary added assurance of C
structural reliability. Therefore, it is recommended that relief be granted from the volumetric examination requirements for the subject branch connection welds with the following provisions:
(a) The proposed surface examination of the saddle-to-pipe fillet welds should be performed in lieu of the C:
Code-required examinations.
(b) A visual examination of the joints should be performed during periodic hydrostatic testing in accordance with IWB-5000 as proposed.
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Re ferences i
References 3, 5, and 8.
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Puzp Pnssure Boundaries
_1, Relief Request CR-6, Recirculation Pump Casing Examinations, I
Category B-L-2, Item B12. 20 Code Requireent The internal surfaces of at least one pump in each group of
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pumps performing similar functions in the system (e.g., recircu-lating coolant pumps) shall b'e visually examined (VT-3) during each inspection interval.
Examinations may be performed on the same PJmp selected for volumetric examination of welds.
The examinations may be performed at or near the end of the inspection in terval.
f' Code Relief Request Relief is requested from visually examining the reactor rccirculation pumfs.
Proposed Alternative Examination _
As standard mintenance practice dictates, when a pump of this type is disassembled for maintenance, examina tion of the pum9
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internals and internal pressure boundary surfaces will be per-formed to the catent practical.
Licensce's Basis for Peguesting Felief Each Quad Cities unit has an ISI Class 1 recirculation pump in each of the two 26-inch diameter recirculation loops.
These pumps function during norml reactor operation to provide forced recirculation through the core, The basis for this relief is predicated on the following two 3
points:
(1 ) to complete the subject examination, large expenditures of man-hours and man-rem are required, with essentially no compensating increase in plant safety, and g,
( 2) the structural integrity afforded by the pump casir.g material utilized will not s10nificantly degrade over the li fetime of the pump.
Based on data compiled from an actual recirculation pump dis-asse':bly, it is expected that approximately 1000 man-hours and 50 g
man-rem exposure would be required to disassemble, inspect, and reassenble one pump. Performing this visual examination under 3
17 i
D r-
'r-adverse conditions, such as high dose rate (30-40 R/hr) and poor as-cast surface condition, realistically provides little additional information as to the pump casing integrity.
7 The recirculation pump casing material, cast stainless steel
( ASTM A351-CF-8), is widely used in the nuclear industry and has performed extremely well.
The presence of some delta ferrite (typically 57, or more) imparts substantially increased resistance to intergranular stress corrosion cracking.
The delta ferrite g
also results in improved pitting corrosion resistance in chloride containing environments.
Commonwealth Edison feels that adequate safety margins are inherent in the basic pump design and that the health and safety of the public will not be adversely affected by performing the visual examination of the pump internal pressure boundary surfaces only when the pumps are required to be disassembled for maintenance.
7
_ Evaluation The Code-required visual examination specified is to determine whether unanticipated severe degradation of the casing W>a or corrosion.
is ocr9rrino f!'!e 9 thmea 8 7 e
%ce, vu.6m ~ f of pumps soieiy ibe making this visual
~
.n.a does 14t cpp;c: warranted in view of th.s redhtien exposure.
The 10 ensee has committed to examining th'. pump internals and internal pressure boundary serfurt h the Min ?
m vr4 pr.netict1 s e,.; p.fy 4 m m e hg ru g e wear:
commitment should be accepted.
b Conclusions and Recommendations Based on the above evaluation, it is concluded that for the examinations discussed above, the Code requirements are imprac-tical.
It is further concluded that the alternative examination discussed above will provide necessary added assurance of g
structural reliability.
Therefore, the following are recommended:
l (a) Relief should be granted from visually examining these casings for the current inspection interval.
L (b) The first pump disassembled for maintenance during this 4
interval should be examined by the most feasible means as proposed, t
References References 3 and 5.
18 g
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F.
Valve Pressure Boundaries 1.
Relief Request CR-7, Internal Surfaces of Valves, Category B-M-2,
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Item B12.'40 Code Requirement The internal surface of at least one valve in each group of
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valves with the same construction design (e.g., globe, gate, or check valve) and manufacturing method that perform similar functions that exceed 4 in, in diameter in the system (e.g.,
containment isolation and system overpressure protection) shall be visually examined (VT-3) during each inspection interval.
Exami-nation may be performed on the same valve selected for volumetric
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examination of welds.
The examinations may be performed at or near the end of the inspection interval.
Code Relief Request
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Relief is requested from examining the internal surfaces of Class 1 valves.
.O tre;21% alternative Examination An examination of the interel prnsure hourrJur whos, will be perferr#, w mt catent p%1re e m ti.h. valve is
? 9tMgf ln 5% :A W,:d Mc get pnSos.
0 Licensee's Basis for Requesting Relief In the Class 1 system, there are 51 valves which are greater than 4 inches nominal pipe size. These valves vary in size,
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design, and manufacturer but are all manufactured from either cast stainless steel or carbon steel.
None of the valve body casings is welded.
The requirement to disassemble primary system valves for the sole purpose of performing a visual examination of the internal
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pressure boundary surfaces has only a very small potential of increasing plant safety margins and a very disproportionate impact on expenditures of plant manpowar and radiation exposure.
Performing these visual examinations, under such adverse conditions as high dose rates (10 R/hr) and poor as-cast surface
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condition, realistically provides little additional information as l
to the valve casing integrity.
r (t
For approximately 20% of these valves, the reactor vessel core must be completely unloaded and the vessel drained to permit disassembly for examination.
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The performance of both carbon and stainless cast valve Based on this bodies has been excellent in all BWR applications.
experience and both industry and regulatory acceptance of these alloys, continued excellent service performance is anticipated.
' l A more practical approach that would essentially provide an equivalent sompling program and significantly reduced radiation exposure to plant personnel is to inspect the internal pressure boundary of only those valves that require disassembly for main-This would still provide a reasonable sampling tenance purposes.
of primary system valves and give adequate assurance that the
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integrity of these components is being maintained.
- Eval uation The Code-required visual examination specified is to
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determine whether unanticipated severe degradation of the body is occurring due to phenomena such as erosion or corrosion. However, the disassembly of large valves to the degree necessary to inspect the internal pressure-retaining surfaces (bodies) is a major To do this disassembly effort in terms af exposure of personnel.
solely to perform a visual examination of the internal body is
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The licensee's proposed alternative to examine impractical.
valves disassembled for maintenance is adequate to determine the overall condition of Class 1 valves.
Conclusior.s and Recommendations C,
Based upon the above evaluation, it is concluded that for the It valves discussed above, the Code requirements are impractical.
is further concluded that the alternative proposed examination discussed above will provide necessary added assurance of struc-
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tural reliability. Therefore, the following are recommended:
Relief should be granted from the Code requirement to (a) visually examine the internal surfaces of Class 1 valves.
I (b) Any valves disassembled for maintenance should be Code examined as proposed.
- g References i
References 3 and 5.
l g, j
20 l[
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II. CLASS 2 COMPONENTS A.
Pressure Vessels and Heat Exchangers Relief Request CR-8, Residual Heat Removal Heiat Exchanger _
f 1.
Nozzle-to-Shell Welds, Category C-B, Items C2.21 and C2.22 Code Requirement
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Welds joining nozzles to vessels greater than 1/2-in, nominal thickness radii are to be examined by surface and volumetric methods in accordance with Figure IWC-252d-4 each interval.
Nozzle inside radii are to be volumetrically examined in accordance with Figure IWC-2520-4 each interval.
(
For multiple similar vessels, the examinations may be limited to those required on the equivalent of one vessel.
Code Relief Request i
There are two 18-in.-diameter nozzles in the Class 2 portion of each of the two RHR system heat exchangers that are fabricated These saddles are fillet-welded over with reinforcement saddles.
Relief is the actual pressure-retaining nozzle-to-shell welds.
requested from the Code-required examinations on these nozzles.
Proposed Alternative Examination Surface examinations of the reinforcing ring welds will be A visual examination for evidence of performed each interval.
leakage will also be conducted in r.cordance with the Subsection C
The station's procedure will be revised to IWC-5000 requirements.
insure the performance of the alternative examinations.
Licensee's Basis for Requesting Relief
'C The fabrication of these nozzle-to-shell welds precludes any The design does, how-type of volumetric or surface examinatf or..
ever, provide additional strength at the joint and results in Integrity of the pressure-lower stresses at the internal weld.
retaining joints will be monitored by periodic system pressure and The saddle weld integrity will be determined C
hydrostatic tests.
by surface examinations of the fillet welds.
illed vent holes.(g) reinforcement saddles were fabricated with drThes Th obstructed pressure-retaining weld has developed any through-wall This vent hole will be observed during the required g
defect.
21 C
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Section XI, IWC-5000 tests. Commonwealth Edison Company feels that this inspection program provides for adequate margins of safety in the continued use of the heat exchangers.
g Evaluation The reinforcing saddles covering these nozzles prevent the performance of the Code-required examinations. The 1980 edition I
of the Code (Winter 1981 addenda) recognizes that the reinforced design exists and has in those cases specified that the saddle-to-pressure boundary welds be surface examined. The newer Code also requires the proposed visual examination of each joint during pressure tests.
I Hence, it would be reasonable to follow the newer Code requirements to surface examine all applicable saddle-to-pressure boundary fillet welds and do the proposed visual VT-2 examination during pressure tests.
I Conclusions and Recommendations Based upon the above evaluation, it is concluded that for the welds discussed above, the Code requirements are impractical.
It is further concluded that the alternative examinations discussed above will provide necessary added assurance of structural reli-g.
ability.
Therefore, it is recommended that relief be granted based on the following provisions:
(a) The proposed surface examination of the reinforcing saddle fillet welds should be performed in lieu of the Code-required examinations.
g (b) A visual examination of the welds should be performed during periodic hydrostatic testing in accordance with IWC-5000 as propn:ed.
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References References 3, 4, 5, and 8.
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B.
Piping 1.
Relief Request CR-10, Piping System Branch Connection Welds, I
Category C-F, Item C5.31 Code Requirement
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The surfaces of 100% of each circumferential weld in pipe branch connections shall be examined in accordance with Figure IWC-2520-9 during each inspection interval.
The welds selected for examina-tion shall include:
a.
all welds at locations where the stresses under the loadings
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resul ting from Normal and Upset plant conditions as calculated by the sum of Equations 9 and 10 in NC-3652 exceed the specified value; b.
all welds at terminal ends (see (e) below) of piping or branch runs;
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c.
all dissimilar metal welds; d.
additional welds, at structural discontinuities (see (f) below) such that the total number of welds selected for examination includes the following percentages of circumferential piping
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wel ds:
1.
none of the welds exempted by IWC-1220; 2.
none of the welds in residual heat removal and emergency core cooling system (see (g) below);
3.
50% of the main steam system welds;
(.,
4.
25% of the welds in all other systems.
e.
terminal ends are the extremities of piping runs that connect to structures, components (such as, vessels, pumps, and valves) or pipe anchors, each of which act as rigid restraints or provide at least two degrees of restraint to piping thermal expansion; C
f.
structural discontinuities include pipe weld joints to vessel nozzles, valve bodies, pump casings, pipe fittings (such as, elbows, tees, reducers, and flanges conforming to ANSI Standard B16.9), and nine branch connections and fittings;
(.
g.
examination requirements are under development.
For welds in carbon or low alloy steels, only those welds showing reportable preservice transverse indications need to be examined for transverse reflectors.
(~
23
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i,e M-
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Code Relief Request Relief is requested from the Code requirements to examine 45 Class 2 branch-to-pipe welds (25 welds for Unit 1 and 20 welds for 7
Unit 2) greater than 4 in, diameter because they are covered by reinforcing saddles.
Proposed Al ternative Examination g
A surface examination of the saddle fillet welds will be performed.
Also, a visual examination of these joints for evidence of leakage will be conducted during the pressure tests required by IWC-5000.
The station's procedure will be revised to insure performance of the alternative examinations.
7 Licensee's Basis for Requesting Relief The design of certain Class 2 branch pipe connection welds calls g
for the use of reinforcement saddles. These saddles are fillet-welded over the actual pressure-retaining branch pipe-to-main pipe welds, completely encasir.g them.
The fabrication of these joints precludes any type of surface examination. Additional assurance of the continued integrity of 7
joints fabricated in this fashion is afforded by the fact that the reinforcement saddle strengthens the joint and reduces the stresses on the internal weld.
The reinforcement saddles were fabricated-with drilled vent hol es.( 8) These holes provide a means to determine if the g'
obstructed pressure-retaining weld has developed any through-wall de fect.
This vent hole will be observed during the required Section XI, IWC-5000 tests.
Commonwealth Edison Company feels that this inspection program provides for adequate margins of safety in the subject branch connections.
0 Evalua tion The reinforcing saddles covering these branch connection welds prevent the performance of the Code-required surface examinations.
g For nozzles, the 1980 Edition of the Code (Winter 1981 Addenda) recognizes that the reinforced design exists.
In those cases, the Code has specified that the saddle-to-pipe welds, rather than the pressure-retaining welds, be surface examined.
It would be appropriate, therefore, to extent this philosophy to similar designs in branch connections.
_g 24
i c
Hence, a reasonable alternative program to that required by the Code would be to surface examine all applicable saddle-to-pipe fillet welds and do the proposed visual VT-2 examination during 1
pressure tests.
Conclusions and Recommendations
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Based upon the above evaluation, it is concluded that for the welds discussed above, the Code requirements are impractical.
It is further concluded that the alternative examinations discussed in the evaluation above will provide necessary added assurance of structural reliability.
Therefore, the following are recommended:
(
(a) Relief should be granted from the surface examination requirements for the subject branch connecticn welds.
(b) Each saddle-to-pipe fillet weld should be surface examined as proposed at the Code required frequency.
f (c) The joints should be visually examined as proposed.
References it References 3, 4, 5, and 8.
- (.
C.
Pumps tb relief requests.
D.
Yalves l
2 relief reques ts.
((
i i
25
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III. CLASS 3 COMPONENTS No relief requests.
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IV. PRESSURE TESTS A.
Class 1 Pressure Tests I
No relief requests.
B.
Class 2 Pressure Tests f
1.
Relief Request CR-12, Hydrostatic Testing of the High Pressure Coolant Injection Turbine, Category C-H Code Requirement I
All pressure containing components within Class 2 systems are to be hydrostatically tested each interval.
For components that operate at or above 2000F, the test pressure is to be 1.25 times the setting of the lowest-set relief / safety valve that protects it.
E Code Relief Request Relief is requested from hydrostatically testing the high pressure coolant injection (HPCI) turbine.
b Proposed Alternative Examination A system functional test will be performed in lieu of the /-
/,/
required hydrostatic test.
I Licensee's Basis for Requesting Relief The labyrinth seals used in the HPCI turbie.e are designed to prevent steam from leaking out of the turbine casing.
The fragile design of the seals is not intended to retain water under pressure. Therefore, performing a hydrostatic test on the turbine g'
casing will permanently damage the turbine seals.
Evaluation It is clear that a turbine's shaft seals can be damaged by g
forcing high pressure water through them. The Code, however, 0
l
f allows the use of steam for testing a steam-containing system.
Even so, a turbine is fragile and a regulation hydrostatic test would not be practical.
The only reasonable way to pressure test p
a turbine casing is to operate the turbine normally with steam, as the licensee has proposed. This should be conducted at the highest attainable pressures consistent with technical specification limitations and manufacturer's guidelines. This approach should be adopted as an alternative to the Code-required testing.
(
Conclusions and Recommendations Based on the above evaluation, it is concluded that for the HPCI turbine, the Code-required hydrostatic test is impractical.
'I It is further concluded that testing the turbine as described above will provide necessary eided assurance of structural in tegri ty.
Therefore, relief should be granted as requested, provided that the alternative pressure test, proposed by the licensee, is performed at the highest attainable pressures consistent with technical specifications and manufacturer's I
gui del ine...
References I'
Reference 3 and 5.
1 0
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27 l
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f-V. GENERAL f
A.
Ultrasonic Examination Techniques 1.
Relief Request CR-9, Calibration Block Documentation
'l Code Requirement The applicable Code section for UT of ferritic vessels greater than 2-in thick is Article 4 of Section Y.
The following paragraphs specify calibration block properties:
't T-434.1.1 - Block Selection.
The material from which the block is f abricated shall be from one of the following:
(1) nozzle drop out from the component I
( 2) a component prolongation (3) material of the same specification, product form, and heat treatment as one of the materials being joined.
_r T-434.1.2 - Cl ad. Where the component material is clad, the block shall be clad to the component clad nominal thickness
+ 1/8 in. (+3.2 mm).
Deposition of clad shall be by the automatic iiiethod used on the component. Where the automatic method is impractical, deposition of clad shall be by the manual method used to cover the circumferential welds of the component.
It is desir-
-r able to have component materials which have been clad before the
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dropouts or prolongations are removed.
T-434.1.3 - Heat Treatment.
The calibration block shall receive at least the minimum tempering treatment required by the
(
material specification for the type and grade and a postweld heat treatment of at least 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />.
Code Relief Request L
Relief is requested to use a reactor vessel calibration block that is not certified to mat the above current requirements.
l
- C 28
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C Proposed Alternative Examination Continued use of the existing calibration block is proposed.
g The present reactor vessel calibration block will be demonstrated to have acoustic attenuation and velocity properties which fall within a range of straight beam longitudinal wave velocity and attenuation as found in the reactor vessel. However, since Quad Cities Station reactor vessels are 1007, clad on the I.D. surface, this check will be completed on the clad component and appropriate g
reviews made by the CECO Level III examiner to verify the accept-
~
ability of the block.
Licensee's Basis for Requesting Relief b
Quad Cities Station currently utilizes a calibration block which lacks documentation consistent with the requirements of current editions of the Code.
The documentation requirements existing at the time of its fabrication did not require trace-ability to the material's chemical or physical certifications.
As a result, the only documentation available for the existing block g
is verification of the appropriate P-number grouping.
Previous inservice inspections have been performed utilizing the above-mentioned block and its use would provide continuity in the ISI progtam.
It would be impractical to fabricate a new cali-bration block in order to satisfy the documentation requirements p
of the current Code.
Existing records, which indicate the approp-riate material P-grouping, provide adequate assurance that the block will establish the proper ultrasonic calibration and sensi-tivi ty.
Additionally, since both reactors' vessels are 1007, clad on the I.P. surface, there is nc way to meet the requirement of verifying the acoustic properties of the block against the clad g'
component.
Evaluation U
The existing reactor vessel calibration block cannot be shown i
to meet current material requirements. However, the block has l
been used to establish reactor vessel material history and should I
continue to be used for ultrasonic testing of vessel welds so that past and future results can be correlated.
I Records exist that verify the appropriate P-number grouping for the block.
Thus, there is assurance that the block can be demonstrated to have adequate acoustic properties.
i 29
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l
. t-a Conclusions ar.d Recommendations f
Based on the above evaluation, it is concluded that for the calibration block discussed above, the Code requirements are im-practical.
It is further concluded that the alternative discussed above will provide necessary assurance of the reliability of ultrasonic testing results. Therefore, it is recommended that 7
relief be granted from the Code-required method of calibration block fabrication, and the present calibration block should continue to be used for reactor vessel weld examinations.
References
(
References 3 and 5.
[
7 L
C C
.L 30 g
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REFERENCES i
1.
Science Applications International Corporation, Technical Evaluation Report, Quao Cities Nuclear Power Station, Units 1 and 2, Inservice Inspection Program, SAI Report No. 186-028-30, September 17, 1982.
(
2.
D. B. Vassallo (NRC) to D. L. Farrar (CECO), May 19, 1983; SER on First Interval ISI Pro 9 ram.
f' 3.
T. J. Rausch (CECO) to H. R. Denton (NRC), February 17, 1983; Second Interval ISI Program.
4.
B. Rybak (CECO) to H. R. Denton (NRC), September 7,1984; response to
(
informal request for additional information.
5.
B. Rybak (CECO) to H. R. Denton (NRC), January 9,1985; submits revised second interval ISI program.
C 6.
D. B. Vassallo (NRC) to D. L. Farrar (CECO); request for additional information, January 11, 1985.
Ce 7.
B. Rybak (CECO) to H. R. Denton (NRC), February 27, 1985; response to RAI.
8.
T. J. Rausch (CECO) to D. B. Vassallo (NRC), June 15, 1982.
l L
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31 m.