ML20149L542
| ML20149L542 | |
| Person / Time | |
|---|---|
| Site: | Haddam Neck File:Connecticut Yankee Atomic Power Co icon.png |
| Issue date: | 02/16/1988 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20149L536 | List: |
| References | |
| NUDOCS 8802240279 | |
| Download: ML20149L542 (6) | |
Text
4 ENCLOSURE 1 0FFICE OF NUCLEAR RFACTOR REGULATION SAFETY EVALUATION REPORT ON A RE00EST FOR PELIEF FROM INSERVICE INSPECTION REQUIREMENTS CONNECTICUT YANKEE ATOMIC POWER COMPANY (CYAPCO)
HADDAM NECK PLANT DOCKET NO. 50-713 1.
BACKGROUND Paragraph 10 CFR 50.55alg)(4) states that inservice examination of ASME Code Class 1, ?, and 3 components shall be performed in accordarce with Section XI of the ASME Boiler and Pressure Vessel Code and applicable addenda, except where specific written relief has been granted by the Comission. Some plants were designed in conformance to early editions of this Code Section, consequently certain requirements of later editions and adderda of Section XI are impractical to perform because of the plants' design, geometry, and material of construction of the components.
Paragraph 10 CFR 50.55a(g)(6)(i) authorizes the Comission to grant relief from those requirements upon making the necessary findings.
By letters dated September 23, 1987 and October 26, 1987, CYAPCO (the licensee) determined that certain inservice examination reouirements of the 1980 Edition through Winter 1980 Addenda of Section XI of the ASME r
Code at Haddam Neck are impractical to perform during the second ten-year inspection interval. The staff evaluation finds the licensee's supporting technical justification to be conditionally acceptable.
II. RELIEF RE0 VEST AND TECHNICAL JUSTIFICATION A.
Item R9.11. Examination Category R-J, Pressure-Retaining Welds In Piping, Relief Request No. 5 Code Requirement 2.
ASME Section XI requires that a surface and volumetric examination of the weld be performed in acccrdance with the reoufrements of Fig. IWB-2500-8 The extent of examinations in the licensee's program are based on Section XI 1974 Edition, with Addenda through Summer 1975.
Ultrasonic examination requirements from mandatory Appeth Ilfi, Article III-4000 require exanination for:
1.
Reflectors parallel to the weld seam.
The angle beam examination for reflectors parallel to the weld seam shall be perforned by a full V-path from one side or a one-half V-path from two sides of the weld when applicable.
8802240279 800216g3 ADOCK O gDR
2.
Reflectors transverse to the weld seam, a.
The angle beam examination for reflectors transverse to the weld seam shall be performed on the weld crown on a single scan path to examine the weld root by one-half V-path in two directions along the weld, b.
For inservice examination, only those welds showing reportable preservice indications need to be examined for transverse reflectors.
Code Relief Request The licensee requests relief from performing the code required volumetric examination to the extent required by Figure IWB-2500-8.
The reactor coolant system piping welds related to this request are identified as follows:
Isometric Drawina No.
Weld No.
Design Conficuration 16103-20275 SH 22 22-12 Pipe-to-valve 16103-20275 SH 33 33-08 Pipe-to-elbow 16103-20275 SH 33 33-09 Pipe-to-elbow 16103-20275 SH 33 33-12 Pipe-to-valve 16103-20275 SH 43 43-12 Pipe-to-valve Basis for Request The arrangements and details of the Class 1 piping systems and components were designed and fabricated before the examination requirements of Section XI of the Code were formalized.
Generally, limitations exist at pipe-to-fitting welds such as pipe to valve and pipe to elbow, where geometry and surface conditions preclude ultrasonic coupling or access for the required scan length.
Specifically, ultrasonic examinations of the required volume of the cast stainless steel material of the valve and fittino can not be performed due to the high attenuation of materials. 4 full vee path scan from the pipe side of the weld will not penetrate and produce a useful signal to noise ratio.
Furthermore, examination from the fitting side of the weld could not be perfomed due to the geometry.
Proposed Alternative Examination The bottom one-third of the weld received an ultrasonic examination in accordance with the methods provided in the Code. The examination was performed from the pipe side of the weld in all cases. Approximately 50% of each weld required volume was examined with a 45 degree transducer. A Code required surface examination was perfomed on each of the subject welds.
The required visual examinations will be perfonned in accordance with Category B P of the Code.
Staff Evaluation The staff has compared the extent of examination required by ASME Section XI Figure IWB-2500-8 and the geometric configuridios of the subject welds. The staff has determined that the examinations are impractical to the extent required by the Code because of limitations resulting from the design. The licensee has performed the examinations from the pipe side in all cases and examined the 1
bottom one-third of the weld. The Code required surface examination and visual examinations during pressure tests were perfonned. The Itcensee has examined the regions where cracks, if present, are most likely to occur. The staff finds that the limited volumetric exami-nations and the surface and visual examinations provide reasonable assurance of the structural integrity of the welds. Therefore, the staff concludes that relief may be granted as requested by the licensee.
B.
Item B 12.40. Examination Category B-M-2, Valve Bodies. Relief TeqIiest No. 4 Code Requirement A visual examination is required of the valve internal surfaces once during each inspection interval.
Examinations are limited to one valve within each group of valves that are of the same construction desion and mantfacturing method and that perform similar functions in the system. The systems involved are the reactor coolant, core deluge, and residual heat removal system.
Code Relief Request The licensee requests relief from perfonning the Code required e
visual examination on the valve internal surfaces.
The valves related to this request are identified as follows:
MANREM FOR i
S_YSTEM VALVE NUMBE_R EXAMINATION DRAWING NO.
j i
RCS MOV-510 12 16103-20275 SH 46 Core Deluae MOV-871A 7.2 16103-20275 SH 72 RHR MOV-781 2.58 16103-20275 SH 14 RHR MOV-804 4.8 16103-20275 SH 24
)
Bases for Request Four valves are scheduled for examination to fulfill the require-ments to examine one of each type of valve of the same manufacturing method and construction design and that perform similar functions.
None of the valves scheduled for examination or any of the valves of similar type and design are being disassembled for maintenance or repair. The 1987 refueling outage is the last scheduled prior to the end of the second ten-year interval. An ALARA review was performed to determine the expected man rem exposure to perform the inservice examination of each valve. A value of approximately 26.5 man rem was estimated to perform all of the required examinations.
CYAPC0 believes that the examinations performed are impractical and not commensurate with the increased safety achieved by this examination. To disassemble these valves would provide a very small potential for increasing plant safety margins with a dispro-portionate impact on man rem expenditures and resources.
Proposed Alternative Examination The subject valves will receive a visual examination (VT-2) during the Code required pressure tests.
If the valves are disassembled for maintenance, the Code required visual examination (VT-3) will be performed.
Staff Evaluation The licensee estimates that approximately 26.5 man rem would be expended to perform the required examinations. The staff has determined that the disassembly of a functioning valve for the sole purpose of performing a visual examination of the internal surface of the valve body is impractical.
The staff finds that the system pressure will provide an acceptable level of quality and safety. Therefore, the staff concludes that relief may be granted as re(uested.
In the event that a valve subject to visual examination is disassembled for repair or maintenance to a degree that the Code requirement is practical, the staff will require that the visual examination be performed and documented.
C.
Item B.2.11_, Examination Cateaory B-B, Pressure Retainina Welds Jn Ve_s_sels Other Than The Reactor Vessel, Relief Request No.7
_ Code Requirement ASME Section XI requires a volumetric examination of the circumferential
)
shell welds in accordance with the requirements of Fig. IWB-2500-1.
The volume subject to examination is the entire weld, heat affected zone (PAZ) and the adjacent base metal for i the wall thickness, 1
measured from the toe of the weld crown.
4 1
Code Relief Renuest For the pressurizer upper and lower head to shell welds, the licensee requests relief frcn. performing the Code required 100%
voluretric examination, p,asisforRequest There is one weld on the lower head and one weld on the upper head.
The vessel was fabricated prior to the publication of ASME Section XI and the welds were not designed for Section XI voluretric exanination.
The bottom head weld reinforcement is 3.25" wide and the upper head weld reinforcen,ent is 1.5" wide, which precludes 100%
ultrasonic volumetric examination with either the 45-degree or 60-degree angle beam technique without first grinding the welds flush. An ALARA Review was perfortred to determine the expected man-rem exposure to grind the welds flush for examination.
Approximately 16 man-rem was estimated to prepare the welds for the required examinations. This value does not include man-rem estimates associated with staging or insulation removal required to access the welds. The licensee believes that the examinations required by Code are impractical due to origi. sal plant design and that the alternative approach proposed would enhance the examinaticn due to the near-field effects of the ultrasonic examination.
In conclusion, grinding operations required to attain a 100% volumetric examination are not justified considering the impact on man-rem expenditures and resources.
,Prpppsed Alternative Examination The subject welds will receive a volumetric examination of approximately 60% of the Code-required volun.e to the extent possible during the Code-required inspections.. To augment these examinations, a nagnetic particle surface examination has been perforned to supplement the volumetric examination.
In addition, the Code-required system hydrostatic test will be performed.
Staff Evalu,at,ipn The licensee could not perforta a volumetric inspection of the upper region of the weld beneath the weld crown because of the existing design configuration. A volumetric inspection was perforred of the weld root, HC, and adjacent base n+tal in the lower 1/3 of the weld. As an alternative, the licensee perforved a surface examination to supplement the limited volumetric examination.
The staff had determined that the Code required volumetric examination is impractical without removal of the weld crown.
Inservice degradation generally occurs at the inside or outside surface.
The staff further detettnined that an expenditure of
16 man-rem to grind the weld flush is not warranted because the licensee has examined the area of interest.
Therefore, the staff concludes that relief may be granted as requested because the licensee has perfortred an acceptable alternative to the Code-required volumetric examination.
Ill. CO,N_CLUSIONS l
Paracraph 10 CFR 50.55a(g)(4) requires that components (including supports) which are classified as ASME Code Class 1, 2, and 3 meet the requirements, except design and access provisions and preservice requirenents, set forth in applicable editions of ASME Section XI to the extent practical within the limitations of design, georretty and materials of construction of the cortponents. Pursuant to 10 CFR 50.55a(g)(5)(iii),
the licensee deterinined that confortnance with certain Code requirerents are impractical for his facility (1), the staff concludes that theand submitted supporti Pursuant to 10 CFR 50.55a(g)(6) requirerrents of the Code are inpractical and relief may be granted for the issues described in Relief Requests Numbers 4, 5, and 7 subject to the conditions described in this evaluation.
Such relief is autherized by law and will not endanger life or property or the common defense and security and is otherwise in the public interest.
This relief has been granted giving due consideration to the burden upon the licensee that could result if the requirements were imposed on the facility.
Principal Contributor:
M. Hum Dated: Fetruary 16, 1988 i
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