ML20090K147
| ML20090K147 | |
| Person / Time | |
|---|---|
| Site: | Bellefonte  |
| Issue date: | 05/16/1984 |
| From: | Mills L TENNESSEE VALLEY AUTHORITY |
| To: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| REF-PT21-84 NUDOCS 8405240063 | |
| Download: ML20090K147 (2) | |
Text
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W TENNESSEE VALLEY AUTHORITY CHATTANOOGA, TENNESSEE 37401 400 Chestnut Street Tower II g gg18 A0*
May 16, 1984 BLRD-50-438/82-35 BLRD-50-439/82-32 U.S. Nuclear Regulatory Commission Region II Attn:
Mr. James P. O'Reilly, Regional Administrator 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30303
Dear Mr. O'Reilly:
BELLEFONTE NUCLEAR PLANT UNITS 1 AND 2 - OPERATIONAL DZFECTS IN HIGH-PRESSURE INJECTION N0ZZLES AND THERMAL SLEEVES - BLRD-50-438/82-35, BLRD-50-439/82 SIXTH INTERIM REPORT The subject deficiency was initially reported to NRC-0IE Inspector Don Quick on April 29, 1982 in accordance with 10 CFR 50.55(e) as NCR BLN NEB 8206. This was followed by our interim reports dated June 1 and July 28,1982 and March 1, April 11 and November 1, 1983 Enclosed is our sixth interim report. We expect to submit our next report by November 30, 1984. We consider 10 CFR Part 21 applicable to this deficiency.
If you have any questions concerning this matter, please get in touch with R. H. Shell at FTS 858-2688.
Very truly yours, TENNESSEE VALLEY AUTHORITY O S %~
L. M. Mills, Manager Nuclear Licensing Enclosure oc (Enclosure):
Mr. Richard C. DeYoung, Director Office of Inspection and Enforcement U.S. Nuclear Regulatory Commission Washington, D.C.
20555 Records Center Institute of Nuclear Power Operations 1100 Circle 75 Parkway, Suite 1500 Atlanta, Georgia 30339 Babcock & Wilcox Company Attention:
Mr. H. B. Barkley P.O. Box 1260 Lynchburg, Virginia 24505 gyp 1CIAL N
<ert 8405240063 840516 1983-TVA SOTH ANNIVERSARY p
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{DRADOCK05000 An Equal Opportunity Employer
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ENCLOSURE o
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o BELLEFONTE NUCLEAR DLANT UNITS 1 AND 2 OPERATIONAL DEFECTS IN HIGH-PRESSURE INJECTION N0ZZLES AND THERMAL SLEEVES NCR BLN N?B 8206 BLRD-50-438/82-35, FLRD-50-439/82-32 10 CFR 50.55(e)
SIXTH INTERIM REPORT Description of Deficiency Recent inspections at several B&W operating plants revealed defects in the makeup /High Pressure Injection (HPI) nozzles and their thermal sleeves and in the makeup piping upstream of these nozzles. The nozzles are located on each reactor coolant cold leg between the reactor coolant pump and reactor vessel.
The nozzles and sleeves are supplied by B&W under the Nuclear Steam Supply System (NSSS) contract.
The defects include:
. through-wall circumferential crack at the welded joint between the nozzle safe end and the first check valve upstream of the safe end
. loose thermal sleeves
. missing ce worn thermal sleeve retaining buttons The lcose thermal sleeves and missing er worn retaining buttons remove the mechanical restraints which were designed to avoid exposing the nozzle and pipe to a thermal shock condition by preventing sleeve movement in the upstream direction.
Although the degraded components at the affected plants were the same, the resulting damage was not identical. Accordingly, B&W is investigating this concern to determine its cause and to determine if it has generic implications for other B&W plants, including Bellefonte. The Bellefonte nozzle configuration is similar to that at the affected plants except that it is a one-piece construction while the nozzles for the affected plants have a welded safe end. B&W has notified TVA of no similar potential deficiencies in the past for other Bellefonte NSSS nozzles. There are no implications for other TVA plants.
Interim Progress Interim report No. 5 outlined TVA's remaining concerns about the adequacy of the sleeve rerolling for the life of the plant. B&W's responses are documented in i
B&W letter D-4941 dated January 27, 1984. Letter D-4941 resolves TVA's concern about sleeve bypass flow due to gaps between the sleeve and the nozzle bore.
The gaps are on the inboard end of the thermal sleeve, not on the outboard end l
where bypass flow must be limited. Tests peformed by B&W on a 177 fuel assembly (FA) plant mock-up (stainless steel thermal sleeve and nozzle) demonstrated that
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no bypass flow around the inboard end of the sleeve occurred. B&W believes the result would be similar, and perhaps better (due to sharter rolled joint j
interface load loss time during an HPI event) for the Bellefonte 205 FA design because the 205 FA design utilizes a thinner Inconel nozzle and stainless steel thermal sleeves.
l To resolve TVA's conosrn about maintaining the thermal sleeve / nozzle interface load through the completo set of design-life transients, va have request'ed B&W' responsa to the following comment:
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Considering the fact that B&W did not perform design-life cycle thermal testing for the 177 FA plant configuration, the assurances presented in D-4698 do not fully validate a 40-year design life for maintenance of thermal sleeve attachmen t.
This is a concern because a graduated loss of the rolled-interface residual stress field is expected as thermal-transient-induced stress cycles accumulate during plant operation. In D-4698, B&W acknowledges a 10-percent load loss due to the initial HPI event but presents no firm evidence regarding the magnitude of load loss for additional thermal cycles. B&W should provide a quantitative evaluation supporting maintenance of the interface residual stress field for the design life thermal transient.
TVA will submit a final report on this deficiency upon resolution of our l
remaining concerns.
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