ML17174B070
| ML17174B070 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 12/06/1991 |
| From: | Barrett R Office of Nuclear Reactor Regulation |
| To: | Kovach T COMMONWEALTH EDISON CO. |
| References | |
| TAC-M81346, NUDOCS 9112300128 | |
| Download: ML17174B070 (3) | |
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Docket No. 50-249 Mr. Thomas J. Kovach Nuclear Licensing M~nager Commonwealth Edison. Company-Suite 300 OPUS West III 1400 OPUS Place Downers Grove, Illinois 60515
Dear Mr. Kovach:
December 6, 1991
- DISTRIBUTION
' Docket Fi le, POI II-2 r/f JPartlow BBoger RBarrett BSiegel EJordan ACRS(lO)
OC/LFMB GGrant, EDO CY Cheng, MC.EB NRC & Local PDRs TMurley/FMiraglia CRossi JZwo 1 ins ki CMoore OGC GHil 1( 4)
GPA/PA.
POI II-2 gray BClayton, RI II JDavis, MCEB
SUBJECT:
. RELIEF REQUEST NUMBER CR-14 FOR DRESDEN, UNIT 3 (TAC N0.~1346)
In a letter dated November 8, 1991, the staff granted relief from Section XI*
of the ASME Code requirements, pursuant to 10 CFR 50.55a(g)(6)(i) and (a)(3)(ii), related to the sample expansion requirements for fluorescent magnetic particle examinations of the reactor vessel closure ~tuds for one
- refueling cycle if crack indications were found.
This relief was granted for one cycle provided that your fracture mechanics analysis resulted in a critical flaw size for the reactor vessel closure studs that was greater than the minimum size detectable by enhanced ultrasonic (UT) examinations:
The staff has reviewed your fracture mechanics based structural margin evaluation submitted in a letter dated October 3, 1991.
The structural margin assessment was based on a fracture mechanics analysis and fracture toughness-data g~ne~ated using ari actual low toughness closure *stud from Dresden Unit 2.
The acceptable flaw size was determined to be 0.57 inches in depth and the enhanced end shot UT can detect a 0.3-inch deep crack. This acceptable flaw size is determined by subtracting the crack growth during one cycle of operation from the allowable flaw size divided by the square root of two as permitted by IWB-3613,Section XI of the ASME Code~:.The critical crack depth is calculated from the critical stress intensity determined. experimentally.
On the basis of this evaluation, the staff has concluded that the acceptable flaw ~ize can be detected using enhanced ultrason_ic t'esting and *that the *condition 'upon which the relief was granted has been sati~fied. *:
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OOCUMEMT NAME:
81346 KOVACH sincerely:
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- Oiiginal Sign ad By: *
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- Richard J; Barrett, Director Project Oirectbrati IIl-2 Division of Reactor Projects III/IV/V Office of Nuclear Reactor Regulation NRC RlE ClENTER COPY
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Docket No. 50-249 Mr. Thomas J. Kovach Nuclear Licensing Manager Conanonwealth Edison Company-Suite OPUS West I II 1400 OPUS Place Downers Grove, Illinois 60515
Dear Mr. Kovach:
300 DISTRIBUTION Docket File PDIII-2 r/f JPartlow BBoger RBarrett BSiegel EJordan
- ACRS(lO)
OC/LFMB GGrant, EDO CYCheng, MCEB NRC & Local PDRs TMurley/FMiraglia CRossi JZwolinski CMoore OGC GHil 1(4)
GPA/PA PDII 1-2 gray BClayton, Rill JDavis, MCEB
SUBJECT:
RELIEF REQUEST NUMBER CR-14 FOR DRESDEN, UNIT 3 (TAC NO.ttl.346)
In a letter dated November 8, 1991, the staff granted relief from Section XI of the ASME Code requirements, pursuant to 10 CFR 50.55a(g)(6)(i) and (a)(3)(ii), related to the sample expansion requirements for fluorescent magnetic particle examinations of the reactor vessel closure studs for one refueling cycle if crack indications were found.
This relief was granted for one cycle provided that your fracture mechanics analysis resulted in a critical flaw size for the reactor vessel closure studs that was greater than the minimum size detectable by enhanced ultrasonic (UT) examinations.
The staff has reviewed your fracture mechanics based structural margin evaluation submitted in a letter dated October 3, 1991.
The structural margin assessment was based on a fracture mechanics analysis and fracture toughness data generated using an actual low toughness closure stud from Dresden Unit 2.
The acceptable flaw size was determined to be 0.57 inches in depth and the*
enh~nced end shot UT can detect a 0.3-inch deep crack. This acceptable flaw size is determined by subtracting the crack growth during one cycle of operation from the allowable flaw size divided by the square root of two* as permitted by IWB-3613,Section XI of the ASME Code.
The critical crack depth is calculated from the critical stress intensity determined experimentally.
On the basis of this evaluation, the staff has concluded that the acceptable flaw size can be detected using enhanced ultrasonic testing and that the condition upon which the relief was granted has been satisfied.
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\\;ZiUJ91 DOCUMENT NAME:
81346 KOVACH D/ ~
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,...__, \\ /91 Sincerely, Oi:g:nai Slgnad By; Richard J. Barrett, Director Project Directorate 111-2 Division of Reactor Projects 111/IV/V Office of Nuclear Reactor Regulation
Mr. Thomas J. Kovach Conunonwealth Edison Company cc:
Michael I. Miller, Esq.
Sidley and Austin -
One First National Plaza Chicago, Illinois 60690 Mr *. J. Eenigenburg Plant Superintendent Dresden Nuclear Power Station Rural Route #1 Morris, Illinois 60450 U. S. Nuclear Regulatory Corrmission Resident Inspectors Office Dresden Station Rural Route #1 Morris, Illinois 60450 Chairmari Board of Supervisors of Grundy County Grundy County Courthouse
- Morris, Illinois 60450 Regional Administrator Nuclear Regulatory Commission, Region III 799.Roosevelt Road, Bldg. #4 Glen Ellyn, Illinois 60137
- Illinois Department of Nuclear Safety Office of Nuclear Facility Safety i035 Outer Park Drive Springfield, Illinois 62704 Robert Neumann Office of Public Counsel State of Illinois Center 100 W. Randolph Suite 11-300 Chicago, Illinois 60601 Dresden Nuclear Power Station Unit No. 3
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