ML17056A806
| ML17056A806 | |
| Person / Time | |
|---|---|
| Site: | Nine Mile Point  |
| Issue date: | 04/26/1990 |
| From: | NRC |
| To: | |
| Shared Package | |
| ML17056A805 | List: |
| References | |
| NUDOCS 9005030113 | |
| Download: ML17056A806 (24) | |
Text
ENCLOSURE 1
SAFETY EVALUATION OF ADDITIONAL RELIEF BEQUESTS NINE NILE POINT UNIT 1 FIRST TEN-YEAR INSERVICE INSPECTION INTERVAL NIAGARA MOHAWK POWER CORPORATION NINE MILE POINT NUCLEAR STATION UNIT 1 DOCKET NO. 50-220 I.
BACKGROUND INFORMATION 10 CFB 50.55a(g) requires examinations and tests of nuclear power facility piping and components to be performed in accordance with the requirements of the applicable ASHE Section XI Code edition and addenda.
If it is impracti-cal to meet the requirements, the licensee of the facility is required to notify the Commission and submit information in support of the determination that a requirement is impractical to perform.
By letters dated Auoust 16, September 8, and November 9, 1989 Niagara Mohawk Power Corporation transmitted to the NRC revised and additional requests for relief from examination requirements of Section XI of the ASME Code for the First Ten-Year Inservice Inspection Interval at Nine Hile Point Nuclear Station, Unit 1.
These relief requests are additional to or revise some of the requests contained in attachments to letters from Niagara Mohawk Power Corporation dated February 24 and Hay 15, 1989 as evaluated in the staff's letter of August 11, 1989.
They are evaluated herein pursuant to 10 CFR 50.55a(g)(6)(i) to determine if the necessary findings can be made to grant the request.
II.
- BEQUESTS, BEOUIREHENTS SUPPORTING INFORMATION AND EVALUATIONS AND CONCLUSIONS A.
RELIEF RE UEST NUMBER 1 II RR 18, REVISION 0 (8/16/89 LTB., TAC 74187) 9005030113 900426 PDR ADOCK 05000220 a
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1.
COMPONENT IDENTIFICATION System:
Quality Group:
Component
Description:
Various Class 1 Valve Flange Surfaces 2.
ASME CODE SECTIOH XI FIRST INTERVAL INSPECTION REQUIREMENTS Winter 1980 Edition with Addenda through Winter 1981 Class 1, Category B-G-1, Item 86.220 requires VT-1 visual examination.
3.
RELIEF REQUESTED Relief is requested from 100% visual examination of the valve flanae mating surfaces (when disassembled).
Relief is requested from the required examination of one (1) valve in valve group (4C) - shutdown cooling check valve 38-12.
4.
BASIS FOR RELIEF The valve listed was not fully inspected by required ASME Section XI visual methods during scheduled maintenance and disassembly.
ALTERNATE EXAMINATION Ho alternate examinations were performed.
Remaining consistent with NMPC philosophy on pumps stated in the June 16, 1988 submittal to the NRC; inaccessible surfaces of valves will not be examined unless the valve is disassembled for maintenance.
6.
PLANT QUALITY & SAFETY The required system operational,
- leakage, hydrostatic and other pressure tests (as applicable),
provide an acceptable level of assurance of the valve flange integrity.
7.
RADIATIOH CONSIDERATIONS Radiation considerations are not a basis for this request for relief.
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8.
STAFF EVALUATION AND CONCLUSIONS Examination Category B-G-I Item B6.220 requires the valve, flange surfaces to be visually examined to determine the condition of the flange, including such conditions as cracks, wear, corrosion, or physical damage.
The visual examination requirements were not fully performed on the flange of the shutdown cooling check valve 38-12 when the valve was disassembled during the first ten-year inspection interval at Nine Mile Point Unit l.
The licensee has not provided sufficient justification to establish the impractically of performing the examination requirements.
However, the staff has determined that fai lure of the flange in the areas that are required to be examined would lead very likely to leakage of water that would be detected during the system leakage test.
For this reason, the staff's position is that relief is denied and the examination requirements must be rescheduled for the next refueling outage.
B.
RELIEF REQUEST NUMBER I II RR 22 REVISION I (8/16/89 LTR. TAC 74187) 1.
COMPONENT IDENTIFICATION System:
Quality Group:
Component
Description:
Various Class 1 Valve Internals 2.
ASME CODE SECTION XI FIRST INTERVAL INSPECTION REQUIREMENTS Minter 1980 Edition with Addenda through Minter 1981 Class 1, Cate-gory B-M-2, Item B12.50 requires VT-3 visual examination.
3.
RELIEF REQUESTED Relief is requested from 100% visual examination of the valve inter-nal surfaces (when disassembled).
Relief is requested for one (1) valve in each of the valve groups listed below:
VALVE GROUP 4D SYSTEM Emergency Condenser Feedwater VALVE 8 DESCRIPTION REQUIRED EXAM 31-07, 31-08 18" Isolation Valves VT-3 39-03, 39-04 10" Check Valves VT-3
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C VALVE GROUP SYSTEM VALVE 8 DESCRIPTION REQUIRED EXAM 6A Reactor 33-01, 33-02 Water Clean-33-04 up 6" Isolation Valves VT-3 6B Shutdown Cooling 38-01, 38-02 38-13 14" Isolation Valves VT-3 6D Core Spray 4.
BASIS FOR RELIEF 40-01, 11 40-02, 40-05, 12 06 12" Isolation Valves 6" Isolation Valves 09, 10, 12" B'locking Valves VT-3 The valves listed were not fully inspected by required ASME Section XI visual methods during scheduled maintenance and disassembly.
5.
ALTERNATE EXAMINATION No alternate examinations were performed.
Remaining consistent with NMPC philosophy on pumps as stated in our June 16, 1988 submittal to the NRC; inaccessible surfaces of valves will not be examined unless the valve is disassembled for maintenance.
Local Leak Rate Testing is scheduled on the valve groups (4D) and (6B) next outage.
The valves may require disassembly and the VT-3 of the valve internals will be performed at that time.
6.
PLANT QUALITY 8( SAFETY The required system operational,
- leakage, hydrostatic and other pressure tests (as applicable),
provide an acceptable level of assurance of the valve internals integrity.
7.
RADIATION CONSIDERATIONS Radiation considerations are not a basis for this request for relief.
8.
STAFF EVALUATION AND CONCLUSIONS The licensee's basis for not performing the visual examination of the internal surfaces of the valves listed does not provide suffi-cient justification to grant relief.
The staff s position is that relief is denied and the visual examination requirements must be performed during the next refueling outage.
Delaying the examination
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C.
RELIEF RE VEST NUMBER 1 II RR 19 REVISION 0 (9/8/89 LTR., TAC 74852) 1.
COMPONENT IDENTIFICATION System:
Quality Group:
Component
Description:
Main Steam Valve Body Welds 2.
ASME CODE SECTION XI FIRST INTERVAL INSPECTION REQUIREMENTS 1980 Edition with Addenda through Hinter 1981 Class 1, Category B-M-1, Item B12.40 require volumetric examination.
3.
RELIEF REQUESTED Relief is requested from 100% volumetric examination of the volume delineated in Figure IWB-2500-17.
Relief is requested for one (1) of the required welds.
4.
BASIS FOR RELIEF Valve body weld BT-06130-SW-1 was not fully inspected by volumetric method due to limitations imposed by an adjacent sockolet weld.
The Weld Required Volume achieved parallel to the weld axis is 100%.
The Weld Required Volume achieved perpendicular to the weld axis is 80%.
5.
ALTERNATE EXAMINATION No alternate examination was performed.
Alternate examinations are not practical, in that, configuration limitations restrict access to remaining 20% of Weld Required Volume.
6.
PLANT DUALITY & SAFETY The examinations as performed, together with the completed
- leakage, hydrostatic and other pressure tests (as required),
provide an accep-table level of assurance of integrity of the valve body weld and pressure retaining boundary.
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7.
RADIATION CONSIDERATIONS Radiation considerations are not a bais for this request for relief.
8.
STAFF EVALUATION AND CONCLUSIONS The valve body design prevents 100K, coveraqe of the valve body weld BT-06130-SM-1 when scanning perpendicular to the weld axis.
100% of the weld is covered by the circumferential scan.
Compliance with the Code requirement would require modification of the valve to relocate the interfering component socket weld.
The large percen-tage of the volume of the weld and base material examined presents a very high likelihood of detection of any significant flaw.
The staff therefore concludes that relief from examining the weld to the extent required by the code may be granted as requested.
D.
RELIEF RE UEST NUMBER 1 II RR 28 REVISION 0 (9/8/89 LTR.
TAC 0 74852) 1.
COMPONENT IDENTIFICATION System:
Quality Group:
Component
Description:
Feedwater Class 2 Low Pressure System Supports 2.
ASME CODE SECTION XI FIRST INTERVAL INSPECTION REQUIREMENTS 1980 Edition with Addenda through Minter 1981 Class 2, Category F-B, Item numbers F2.10, F2.20, F2.40 require a visual examination.
3.
RELIEF REQUESTED Relief is requested from 100% visual examination of the six (6) low pressure feedwater system supports in exam area listed:
51-A-1 51-H-5 51-H-7 4.
BASIS FOR RELIEF 51-H-10 51-H-17 51-H-23 The supports listed were not inspected due to 100% inaccessibility in fire penetrations.
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5.
ALTERNATE EXAMINATION No alternate examinations were performed.
Alternate examinations are not practical due to lack of component accessibility.
6.
PLANT QUALITY 5 SAFETY The examinations performed on this system, together with the system pressure tests (as applicable),
provide an acceptable level of assur-ance of system integrity.
7.
RADIATION CONSIDERATIONS Radiation considerations are not a basis for this request for relief.
8.
STAFF EVALUATION AND CONCLUSIONS The active deadweight and seismic supports are inaccessible for visual examination in areas where the supports are contained in flamestic fire penetrations.
Compliance with the Code requirement would require extensive measures to remove fire protective coating from the supports or extensive efforts to redesign or relocate the supports.
Therefore, to impose the visual examination requirement on the licensee would result in an undue burden without a compensating gain in plant safety.
Indications of a failed support in the penetrations can be noted by other system tests performed.
The staff therefore concludes that relief from the visual examination requirement for the supports may be granted as requested.
E.
RELIEF REQUEST NUMBER 1 II RR 29 REVISION 0 (9/8/89 LTR., TAC ¹ 74852) 1.
COMPONENT IDENTIFICATION System:
Quality Group:
Component
Description:
Reactor Pressure Vessel Closure Head Flange Welds 2.
ASME CODE SECTION XI FIRST INTERVAL INSPECTION REQUIREMENTS 1980 Edition with Addenda through Minter 1981.
Class 1, Category B-A, Item Bl.40 requires volumetric and surface examination.
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RELIEF RE(UESTED Relief is requested from 100% volumetric examination of the required volume of Category B-A welds delineated in Figure IWB-2500-5.
Relief is requested for all eight (8) sections of the closure head flange weld.
Required surface examinations have been performed.
4.
BASIS FOR RELIEF The closure head flange weld was not fully inspected volumetrically due to component configuration restricting examination of the Weld Required Volume to one directional coverage.
The Meld Required Volume on each section of the flange weld when scanned from the axial, circumferential, and zero-degree directions was calculated to be 86%,
58K and 58%, respectively.
5.
ALTERNATE EXAHINATION No alternate or additional exams were performed.
Additional volu-metric and/or surface examinations would result in an undue burden without a compensating increase in weld integrity.
6.
PLANT EQUALITY 5 SAFETY The examinations as performed, together with the completed system pressure tests (as applicable) provide an acceptable level of assurance of weld integrity and plant safety.
7.
RADIATION CONSIDERATIONS Radiation considerations are not a basis for this request for relief.
8.
STAFF EVALUATION AND CONCLUSIONS The design of the closure head flange limits the transducer motion required to perform a volumetric examination in accordance with Section XI.
Compliance wiht the Code requirements would require a redesign of the closure head flange.
The percentages of the weld required volumes that were examined are sufficiently high enough to provide assurance that significant flaws would have been detected.
The staff therefore concludes that relief from performing 100%
examination of the required volume may be granted as requested.
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RELIEF RE UEST NUMBER 1 II RR 30 REVISION 0 (9/8/89 LTR., TAC 8 74852) 1.
COMPONENT IDENTIFICATION System:
Quality Group:
Component
Description:
Reactor Pressure Vessel Closure Head to Safety Valve Nozzle Welds 2.
ASME CODE SECTION XI FIRST INTERVAL INSPECTION REQUIREMENTS 1980 Edition with Addenda through Winter 1981.
Class 1, Category B-D, Items 83.10 and 83.20 require Volumetric Examination.
3.
BELIEF REQUESTED Relief is requested from 100% volumetric examination of the required volume of Category B-D welds delineated in Figure IWB-2500-7 for the closure head-to-safety valve nozzle welds listed below:
CH-1-576 A-W CH<<1-576 8-W CH-1-576 C-W CH-1-576 D-W CH-1-576 E-W CH>>1-576 F-W CH-1-576 G-W CH-1-576 H-W CH-1-576 J-W CH-1-576 K-W CH-1-576 L-W CH-1-576 M-W CH-3-576 A-W CH-3-576 8-W CH-3-576 C-W CH-3-576 D-W CH-3-576 E-W CH-3-576 F-W CH-5-576 W
4.
BASIS FOR RELIEF The welds listed were not fully inspected by ultrasonic methods due to limitations of design, geometry and material of construction.
The closure head safety valve nozzle weld configuration restricts the Weld Required Volume to one directional coverage.
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ALTERNATE EXAMINATION Ho alternate or additional exams were performed.
Additional volume-tric and/or surface examinations would result in an undue burden without a compensating increase in assurance of weld integrity.
PLANT EQUALITY 5 SAFETY The examinations as performed, together with the completed system pressure tests (as applicable) provide an acceptable level of assur-ance of weld integrity and plant safety.
RADIATION CONSIDERATIONS Radiation considerations are not a basis for this request for relief.
STAFF EVALUATION AND CONCLUSIONS The nozzle-to-closure head weld geometry restricts the ultrasonic transducer movement such that only a percentage of the required volume can be examined in accordance with the requirements of Section XI.
Compliance with the Code requirements would necessitate a change in the design of the closure head-safety valve nozzle interface.
The percentages of coverage of the welds and inner radii of the nozzles range from 25% to 79K with scans performed axially and circumferentially at different beam angles.
The examinations performed on the welds and inner radii in conjunction with the required pressure tests and visual examinations provide assurance of their continued structural integrity.
The staff there-fore concludes that relief from performing 100% volumetric examina-tion of the closure head-to-safety valve nozzles may be granted as requested.
RELIEF BE UEST NUMBER PSIRR3 REVISION 0 (ll/9/89 LTR., TAC 4'5317)
COMPONENT IDENTIFICATION System:
Emergency Cooling equality Group:
A Component
Description:
Pressure Retaining Meld in Piping ASME CODE SECTION XI FIRST INTERVAL INSPECTION RE(UIREtlENTS 1980 Edition with Addenda through Minter 1981 Class I, Category B-J, Item Number B9.11 requires a volumetric and a surface examination.
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RELIEF REQUESTED Relief is requested from 100% volumetric examination of the volume delineated in Figure IWB-2500-8.
Relief is requested for one (1) valve to reducer weld - 39/31-FW-115-24.
BASIS FOR RELIEF The weld listed did not receive full pre-service volumetric inspection as required by ASME Section XI.
ALTERNATE EXAMINATION No alternate examinations were performed.
An acceptable ASME Section XI required surface examination, zero degree ultrasonic weld profile, and construction radiograph examination were performed.
The weld - 39/32-FW-11S-24 is scheduled for replacement next re-fueling outage with the replacement of the adjacent valve 39-02.
Complete pre-service examination - both volumetric and surface will be completed following the replacement modification next refueling outage.
PLANT QUALITY 5 SAFETY The required system operational
- leakage, hydrostatic and other pressure tests (as applicable),
provide an acceptable level of assurance of Emergency Cooling System integrity.
RADIATION CONSIDERATIONS The NMPC ALARA department estimates the radiological exposure to perform all phases of preparation and ultrasonic examination for this one weld will exceed 7.6 man-rem.
STAFF EVALUATION AND CONCLUSIONS The examination of the weld joining the valve and reducer required by Section XI is impractical because the valve body and reducer geometry restricts ultrasonic transducer motion axially and circum-ferentially.
Compliance with the Code requirements would necessitate redesign and thus replacement of the valve which is an action planned to be taken during the next refueling outage when the adjacent valve will also be replaced.
The surface examination and limited ultrasonic examination in conjunction with system pressure tests provide assurance of the weld's structural integrity. The staff therefore concludes that relief from the Code requirement to volumetrically examine the weld 100% may be granted as requested.
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12-III. CONCLUSION Based on the review summarized herein, the staff has determined that pursuant to 10 CFR 50.55a(g)(6)(i) granting relief where the inspection requirements are impractical is authorized by law and will not endanger life or property or the common defense and security and is otherwise in the public interest considering the burden that could result if the requirements were imposed on the faci 1 ity.
Date:
Princi al Contributor George Johnson
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