ML17187A320
| ML17187A320 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 02/15/1996 |
| From: | Stang J NRC (Affiliation Not Assigned) |
| To: | Farrar D COMMONWEALTH EDISON CO. |
| Shared Package | |
| ML17187A321 | List: |
| References | |
| TAC-M93862, NUDOCS 9602220095 | |
| Download: ML17187A320 (3) | |
Text
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UNITED STATES NUCLEAR REGULATORY COMMISSION Mr. D. L. Farrar WASHINGTON, D.C. 2051111 0001 February 15, 1996 Manager, Nuclear Regulatory* Services.
Commonwealth Edison Company Executive Towers West III 1400 Opus Place, Suite 500 Downers Grove, IL 60515
SUBJECT:
-DRESDEN, UNIT 2, FLAW EVALUATIONS (TAC NO. M93862)
Dear Mr. Farrar:
5"o-Z37 By letter dated October 16, 1995, Commonwealth Edison Company (ComEd)
_submitted two flaw evaluations to the NRC for review and approval based on the requirements of American Society of Mechanical Engineers (ASHE) Boiler and Pressure Vessel Code (Code), Sectio_n XI, 1989 Edition.
The evaluations-_have*: -
been submitted as a result of flaw indications in the reactor vessel head:.
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flange weld and recirculation piping welds_.
The flaws were discovered-* durini ultrasonic (UT) examinations conducted during the current refueling outage a~
Dresden, Unit 2.
The examinations were performed in accordance with the;.*
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requirements of the ASHE Code,Section XI.
The first evaluation indicated that UT examinations detected a flaw in the reactor head flange weld that exceeded the allowable flaw size specified in IWB-3500 of the ASHE.Code,Section XI.
The Code requires a flaw evaluation be performed using the criteria of IWB-3610, and* ASHE Code, Appendix A.
The second evaluation indicated that UT examination~ of the reactor recirculation piping found two flaws requiring evaluations. The first flaw is located* in the elbow-to-pipe weld on the Loop A recirculation pump d.ischarge piping. The second flaw indicators were two circumferential cracks about 28 inches apart found in the valve-to-tee weld on the Loop B recirculation pump suction piping.
The flaws dis covered in the rec i rcu 1 a-ti on piping we 1 ds exceed the allowable flaw sizes s~ecified in IWB-3500 thereby requiring flaw evaluations be performed in accordance with IWB-3640, ASHE C.ode, Appendix C, and NUREG-0313.
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The staff's~.;~fe_ty: Ev.aluation (SE) of the flaw evaluations is enclosed. The staff foundyi*h~at~the; current detected flaw depth was 0.52 inch in the head flange weld:~:Thls,. flaW,:.depth is-smaller than the adjusted allowable flaw depth of 0.643;for**a~ l~fuel-cycle fatigue crack growth. Therefore, in accordance wfth the ASHE Code,Section XI, the flaw is acceptable without repair. However, the area containing the flaw shall be reexamined during the next three inspection periods as required-by IWB-2420 of the ASHE Code.
The staff's evaluation concerning flaws in the recirculation pip1ng found that the final crack sizes at the end of the next fuel cycle will not exceed the Code allowable. Therefore, Dresden, Unit 2, can operate for the next fuel I
D. Farrar
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cycle w1thqu~tF~~epa.ir1og the subject flawed welds.
In accordance with the Technical Sp.(c.iif~catfons, the subject welds PDIA-Dl4 and PS2-TEE/202-4B are required to be re,...inspected every refueling outage. Continued plant operation beyond the next fuel cycle should be supported by the results of the piping re-inspection.
This completes the staff review of the subject evaluations and closes TAC No.
M93862.
If you have any questions regarding this issue, please contact me at (301) 415-1345.
Enclosure:
Safety Evaluation cc w/encl:
See next page Sincerely, c-l~
r}.
ohn F. Sta,, Project Manager Project Directorate III-2 Div 1s1 on of Reactor Projects "" I II/ lVt'.,,
Office of* Nuclear Reactor Regu~ at1~"',*~.,:~
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Michael. r.~* Miflet;;'-EsquiT'e Sidley and Austin One First National Plaza Chicago, Illinois 60603 Site Vice President Dresden Nuclear Power Station 6500 North Dresden Road Morris, 111 i noi s 60450-9765*
Station Manager Dresden Nuclear Power Station 6500 North Dresden Road Morris, Illinois 60450-9765 U.S. Nuclear Regulatory Co11111ission Resident Inspectors Office Dresden Station 6500 North Dresden Road Morris, Illinois 60450-9766 Regional Administrator U.S. NRC, Region Ill 801 Warrenville Road Lisle, Illinois 60532~4351 Illinois Department of Nuclear Safety Office of Nuclear Facility Safety 1035 Outer Park Drive Springfield, 11*11nois 62704
. Chairman Grundy County Board Administration Building 1320 Un1on-,,~~r~.. **,~~:r::*?~~*,,~~.... 1
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Dresden Nuclear Power Station Unit Nos. 2 and 3
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