ML20058E824
| ML20058E824 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 10/26/1990 |
| From: | Hukill H GENERAL PUBLIC UTILITIES CORP. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| C311-90-2126, NUDOCS 9011070354 | |
| Download: ML20058E824 (3) | |
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r GPU Nuclear Corporation Nuclear
=,om s reo e
Middletown, Pennsylvania 17057 0191 717 944 7621 TELEX 84 2386 -
October 26, 1990 Writer's Direct Dial Number:
C311-90-2126 U.
S. Nuclear Regulatory Commission Attn:
Document Control Desk v
Washington, DC 20555
Dear Sir:
m Three Mile Island Nuclear Station, Unit 1 (TMI-1)
Operating License No. DPR-50 Docket No. 50-289 Inservice Inspection-(ISI) of Reactor Vessel Core Flood Safe-End Welds t,
" n-In accordance with : 10 CFR 50.55a(g) (5) (iii), GPUN's letter of f.
August 20, 1986 requested relief from certain ASME Code Section XI requirements which wo had determined to be u
D impractical. 'Our letter of October 20, 1986 provided additional
.information to support the relief sought for 1987 inspections. In a letter dated March 20, 1987_the NRC provided a Safety Evaluation Report (SER).. which granted. relief for the 1987 e
examinations.- The:SER also identified the additional information that would be needed for.NRC, approval of relief needed for future, a
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"1 outages...The purpose of this letter is to provide the requested L'
information concerning. relief from the liquid' penetrant R
examination ~of.the outer diameter (OD) Weld. surface of the core
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-floodisafe-end-welds, item No. 4 from our'1986 GPUN submittals.
In accordance1with the-requirements'of. Table'IWB-2600 (Category.B-F) of-ASME Section XI, coreiflood nozzle to safe-end welds' connected'to the. reactor vessel require both a. volumetric examination and'an OD: surface examination of the weld for
- dissimilar metal' welds.
The Volumetric examination'is_ performed
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from.theLID of the nozzlo using the B&W'ARIS tool and the surface examination' requires a' liquid penetrant examination =from the OD
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surface; -Due'to theihigh radiation levels and. access re'strictions at theknozzle locations, GPUN has. requested-relief to?use an alternate: examination method.to reduce personnel i
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>g exposure during<the. performance'of these examinations to
- M Las-low-as-re.csonably-achievable-(ALARA).
An acceptable; alternative for the liquid penetrant OD-surface examination makes use of an= ultrasonic; technique working from the inside: diameter (ID) of the nozzle using the ARIS.ool.
011070354 901026
.{DR ADOCK 05000289 PDC h0Y1
. GPU Nuclear Corporation is a subsidiary of General Public Utilities Corporation
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C311-90-2126 October 26, 1990 To. justify this proposed alternate examination technique, a demonstration was performed at B&W's Lynchburg, Virginia facility on August 8, 1989.
In this demonstration B&W showed how " opposite surface" flaws can be detected utilizing state-of-the-art examination techniques and equipment.
Representatives of the NRC were present for;this demonstration, as. documented by the NRC in a Crystal Rivtr Inspec'. ion Report No. 50-302/89-21.
The purpose of the' demonstration was to confirm the capability to detect of the minimum size (through-wall dimension) reflector originating.at the opposite'(OD) surface in an actual ARIS-examination-from the ID of the nozzle.
Although the actual ARIS w
, tool could not be used for this demonstration, a robotic arm manipulator was used which simulated the ARIS scanning motions to
~be used for the actual UT examination.
The examination technique was demonstrated on a mock-up containing a weld; of the; same materials and dimensions as the TMI-1 core Flood safe-end welds.
Notches-were located on-the outside diameter of Ethe ' mock-up in, both base materials: adjacent 1 to the weld,.the buttering, and weld material.
These notches were detected and-recorded using'the B&W data acquisition and imaging system,
.ACCUSONEX,c and a 45-degreerrefracted longitudinal wave.
the actual: fieldL examination wili use a 70-degree refracted slongitudinal' wave'for detection of flaws located'in the inner.
36 ' volume (ID) in the area of interest and a 45-degree refracted
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Llangitudinal wave will be used to examine the remaining area of interest.
Use of refracted longitudinal' waves for crack detection
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'has beenfrecognized.as_the best UT-method available for flaw
- detection in dissimilar metal 1 welds as: documented-in NRC
.Information, Notice 90-30):"UltrasonicfInspection Techniques 1for Dissimilar Metal' Welds."'
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OurfAugustL20,--1986 letter statednthat.the.ASME Code' allows 4
- acceptance of:tejectable liquid penetrant detected 1 flaws based on sizing;using ultrasonic. examination methods.
The.GPUN approach of Jperforming1ultraronic examination'only_is considered within:the.
1basisJofLCodelrequirements.
We.also: stated inatheasame letter =that-cumulative-cexposureito perform the liquid penetrant = examination'is estimated to'be 43 Person-Rem.
Because the' installation of.
' temporary. shielding.in the core flood nozzle area is impractical-acceptable alternate examinationftechnique is.available,=the L
- and9an1 required:Section XI Code-inspection requirements'are. determined to:
bes impractical'..Therefore,..the1 requested relief is warranted: and shouldsbe granted.
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C311-90-2126 October 26,.1990 As a matter of precedent, in a letter dated September 21, 1990 (TAC NO. M75327), the NRC approved a similar request for use of
_ thia' technique at_the Davis Besse plant where B&W also was the
- contractor.
TMI-1 Technical Specifications require that GPUN apply the applicable ASME Code except where specific written relief has been granted.
Examination of these welds is planned for the Cycle 9 Refueling (9R) Outage, currently scheduled to begin in
- October, 1991.
Therefore, GPUN requests that specific written relief be granted by April 1, 1991 in older that'our plans and
. procedures for the 9R outhge mhy be-completed realizing a 43 Rem dose savings.
Sincerely, f
e D.
kill Vice President and Director, TMI-1 HDH/MRK cc:
NRC, Director =, Project Directorate I/4
-NRC'~ Senior Resident Inspector, TMI y;
'NRC,' Senior Project Manager, TMI-1 NRC, Region I Administrator' 1^
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