ML20207B842
| ML20207B842 | |
| Person / Time | |
|---|---|
| Site: | Fort Calhoun  |
| Issue date: | 07/29/1988 |
| From: | Morris K OMAHA PUBLIC POWER DISTRICT |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| LIC-88-056, LIC-88-56, NUDOCS 8808040208 | |
| Download: ML20207B842 (4) | |
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Omaha Public Power District 1623 Harney Omah6. Nebraska 68102 2247 402/536 4000 July 29, 1988 LIC-88-056 U. S. Nuclear Regulatory Commission ATTN:
Document Control Desk Mail Station Pl-137 Washington, DC 20555
Reference:
Docket No. 50-285 Gentlemen:
SUBJECT:
Relief Request From ASME Boiler and Pressure Vessel Code Section XI 0maha Public Power District (0 PPD) is forwarding, for approval, the attached relief requests for the Fort Calhoun Sta'. ion.
The arcas in question are 1) some previously unidentified longitudinal weld seam 3 in Fort Calhoun Station's Class 2 piping, 2) two circumferential pipe-to-pipe shop welds on the 32" 10 RCS hot leg piping, and 3) six welds on 2" field routed press: 'ter mini-spray lines.
l l
Pursuant to 10 CFR 50.55a(g)(5)(iii), Omaha Public Power District is requesting relief from performance of these exams until a practical exam plan is developed i
in accordance with the action proposed in Attachment 1.
Omaha Public Power Dis-trict is proceeding with the proposed action.
The $150.00 review fee required by 10 CFR 170 !s enclosed.
If you have any questions, please contact us.
S i nce rel.v, f
i tr, J. Forris J8 ivision Manager pga.
Nuclear Operations oo I
KJM/rh
$3 Attachment l SI ec c:
LeBoeuf, Lamb, Leiby & MacRae
,' 8 1333 New Hampshire Avenue, N.W.
gg Washington, DC 20036 I
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Ll (c0 kg0g%03 R. D. Martin, NRC Regional Administrator P. D. Milano, NRC Project Manager l
P. H. Hcerell, NRC Senior Resident inspector g
imow~ngmgugoppmunw as w4
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Description of Welds and Proposed Action to be Included in Fort Calhoun's ISI Examination Plan 1.
Lonoitudinal Weld Seams j
During a piping examination, longitudinal pipe welds were observed on some stainless steel safety injection piping that were not identified in the In-service Exam Plan.
Table IWC 2500-1, Item C5.12 of ASME Section XI requires surface examination I
of this type of weld with one third of such welds to be examined during the I
first 40 months nf the ten year interval. OPPD has not met this requirement and requests relief until baseline exams can be completed and the welds added to the ISI program.
OPPD proposes to review material certifications and/or walk down the Class 151, 301 or 601 piping greater than four inches nominal diameter to identify longitudinal weld seams subject to inservice exams. This effort is expected to be completed prior to the 1988 refueling outage. Applicable longitudinal welds will be added to the Ten Year Inservice Exam Plan.
Selection and sched-uling of longitudinal weld exams will be coordinated with selected intersect-ing circumferential welds.
During the first 10-year interval, Fort Calhoun Station's ISI Program was con-ducted in accordance with ASME Secticn XI 74S75 (1974 Edition through the Summer 1975 Addendum). This Code did not specify longitudinal pipe welds as required to be included in the Inservice Exam Plan, but it required axamina-tions of 100% of selected longitudinal welds in fittings. At the beginning of the second interval in 1983, ASME Section XI 80W80 was adopted as Fcrt Cal-houn's ISI Code.
The 80W80 Code requires examination of longittdinal welds in pipe and fittings for a length of 21 wall thicknesses on both sides of each selected circumferential weld.
The surface and volumetric examination procedurer that are used on the select-ed circumferential welds typically caer the required length nf the inter;ect-ing longitudinal weld because the examination covers li to 2 inches on each side of the weld.
Pipe wall thickness in the subject pipe is well under 1" so 2) wall thicknesses lie within the exam area. However, the longitudinal welds have not been identified so no credit is taken for examining the longi-tudinal weid in the ISI Report.
OPPD does not believe that deferral of the longitudinal weld exams until they can be practically implemented constitutes an unsafe condition.
2.
Circumferential 32" RCS Welds Review of the RCS piping spool piece drawings revealed two circumferential pipe-to-pipe shop welds (MCR-1-3, MCR-2-3) on the 32" ID hot leg piping that were not identified in the Inservice Examination Plan. There is one weld in each hot leg pipe at the same relative location. These welds were done in the shop and ground smooth prior to shipping the spool pieces to the site.
Table IWB 2500-1, Item B9.11 of ASME Section XI requires full volumetric exams of this type of weld. OPPD has not met this requirement and requests relief until verification of the welds can be made.
OPPD currently has re-lief on similar type welds to supplement volumetric exams with surface exams and hydrotesting as granted with issuance of Amendment 46.
. g.
The hot leg pipes are.centrifuga11y cast Stainless Steel pipe sections with a minimum wall thickness of 31".
Since centrifuga11y cast stainless steel is not always amenable to ultrasonic (UT) examination, UT exams will be done and evaluated to determine if acceptable results can be obtained. Omaha Public Power District has been working with its ISI contractor to develop a more effective exam procedure for this type of examination.
Since no Preservice Inspection Report is available on these welds, it is con-cluded that no ASME XI preservice inspection was performed on these welds.
These welds are not shown on the Inservice Inspection Isometric Drawings so no inservice inspection has been done either.
OPPD proposes to do an ultrasonic inspection of both of these areas during the 1988 refueling outage to verify the existence of these welds.
If the welds are found to exist as shown on the drawings, a baseline exam will be done and these welds will be added to the Ten -Year Inservice Examination Plan.
OPPD does not believe this constitutes a safety concern because:
a) The welds were examined and found acceptable in accordance with the con-struction code at the time of fabrication, b) The applicable edition of ASME XI only requires 25% of the Class I welds to be inspected during each 10 year interval.
The welds which have been selected have been welds suspected of having high stress levels, such as welds near discontinuities and rigid restraints.
The omitted welds are pipe to pipe welds that are expected to have relatively low stress levels.
This selection criteria follows code recommendations and it is probable that these welds would not have been selected for examination if they had been identified.
c) Required pressure testing of the primary piping has been conducted to verify system integrity.
3)
Six Welds on 2" Field Routed Pressurizer Mini-Soray lines Six field welds (2-PSS-15/51-53, 2-PSS-23/51-53) in the 2" nominal OD portion of the pressurizer mini-spray lines were found on isometric drawingr RC-2115 and RC-2116.
These welds were not identified on either the preservice or in-service isometric drawings and no preservice or inservice inspection has been reported in the PSI or ISI reports.
Table IWB 2500-1, Item 89.21 of ASME Section XI requires surface exams of this type of weld with one third of such welds to be examined during the first 40 months of the 10 year interval.
OPPD has not met this requirement and requests relief until these welds can be incorporated into the ISI Program.
Liquid penetrant (PT) exams were performed on these welds as part of the con-struction requirements for these lines.
The reports from these exams are part of OPPD's permanently retained records.
OPPD proposes to correct the exclusion of these welds by including them in the ISI Program, taking credit for the PT exams performed during construction as satisfying the preservice exam requirement, evaluating the 10 Year Inservice Exam Plan to determine what impact the addition of these six welds has on Class I weld selection and making appropriate revisions to the weld selection tables in the Inservice Exam Plan.
OPPD does not believe, the omission of these welds from the Inservice Inspec-tion Plan to date has caused an unsafe operating condition because:
a) The PT weld examinations that were done to satisfy the construction code requirements are equivalent to the PSI examination requirements.
b) The Reactor Coolant System is leak tested at 2150 psi prior to power operation following each refueling outage.. Any problem with these welds would probably have been detected as a leak before the pipe would break, c) Since ASME XI requires examination of 25% of this class of weld each ten years, it is probable that these welds would not have been selected for examination even if they had been identified.
OPPD does not believe that the omission of these welds from the Inservice Inspec-tion Plan to date has caused an unsafe operating condition.
OPPD requests relief only until such time that the requirements can be fully incorporated into the ISI Program and is proceeding with the proposed actions presented above in anticipa-tion of approval.
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