ML20215K228
| ML20215K228 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 10/20/1986 |
| From: | Hukill H GENERAL PUBLIC UTILITIES CORP. |
| To: | Stolz J Office of Nuclear Reactor Regulation |
| References | |
| 5211-86-2178, NUDOCS 8610280048 | |
| Download: ML20215K228 (5) | |
Text
a GPU Nuclear Corporation Nuclear
- =,om:r8o Middletown, Pennsylvania 17057 0191 717 944-7621 TELEX 84 2386 Writer's Direct Dial Number:
October 20, 1986 5211-86-2178 Office of Nuclear Reactor Regulation Attn: John F. Stolz, Director PWR Pro.jects Directorate No. 6 U.S. Nuclear Regulatory Commission Washington, DC 20555
Dear Mr. Stolz:
Three Mile Island Nuclear Station, Unit 1, (TMI-1)
Operating License No. DPR-50 Docket No. 50-289 Response to NRC Requests Concerning Inservice Inspection (ISI)
Relief from Certain Code Requirements In accordance with 10 CFR 50.55a(g)(5)(iii), our letter of August 20, 1986 (5211-86-2132) requested relief from certain ASME Code Section XI ISI requirements that GPUN determined to be impractical. to that letter described the basis for concluding that compliance with the specified requirements would result in hardship or unusual difficulties without a compensating increase in the level of quality and safety.
And for each of our relief requests, we proposed alternatives for providing an acceptable level of quality and safety.
During a conference call on September 16, 1986, the NRC requested additional information and clarification needed in order to complete its review. to this letter provides the information as requested, where each numbered item corresponds to the same item number as in Attachment 1 of our August 20, 1986 letter. The information provided in the previous letter however is not repeated in Attachment 1 to this letter. As we have previously indicated, GPUN would appreciate NRC review of these items such that we can resolve them as soon as possible, in particular the first two items which need to be resolved prior to the 6R Outage in November.
Si ncerely,
. D. Hu ;ill Vice President & Director, TMI-1 HDH/MRK/spb:0681A e61020004e 86102o d
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J. Thoma
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Attachments GPU Nuclear Corporation is a subsidiary of the General Public Utilities Corporation
ATTACWENT 1 1.
The letdown coolers (MU-C1 A/B) are of a helical coil design whose function is to cool reactor coolant water prior to entrance into the makeup and purification demineralizers. The welds involved are located on the inlet and outlet manifolds identified as assemblies 2Al and 2A2 on drawi ng NU-D-1092-1.* Each manifold contains one continuous weld for the full length of the manifold but for ISI documentation and location purposes each manifold is considered to have two welds each. GPUN intends to replace both coolers during the upcoming 6R Outage. A pre-service examination will be performed on the accessible portions of these welds in both coolers prior to installation. Also, prior to the expiration of the present interval, inservice examination will be performed on the accessible portion of a percentage of the total number of these welds as required by the Code.
The coolers are located in the letdown cooler room in the Reactor Building basement where previous plant history indicates radiation fields of about 100 Mr/hr. general area with hot spots in excess of IR/hr.
Also, it is anticipated that radiation fields will increase significantly as plant operation continues.
The areas to be examined intersect the circumferential piping tie-in welds and are the most highly stressed area of the manifold.
It would be expected that any failures in the manifold would originate from this area and would be detected during examination. Failures in the inaccessible portion of the manifold can be detected at an early stage and isolated on noting an increase in the volume and radioactivity of the Intermediate Closed Cooling System which is the heat sink for the coolers.
System hydrostatic and leak tests will be performed on these coolers in accordance with ASME Section XI and will ensure that any degradation to these welds would be detected at an early stage and the component removed from service prior to exceeding normal makeup capabilities.
Therefore, we feel that examination of the accessible portion of these welds in accordance with the Code required frequencies is adequate and meets the intent of the ASME Code.
2.
Pursuant to the requirements of 10 CFR 50.55a(g), we are advising the NRC of our intent to use portions or articles of later Code Publications.
GPUN intends to adopt the 1977 Edition with Addenda through Summer 1978, Article Paragraph IWC-2500, Table IWC-2500-1, Examination Category C-G, Item Number C6.20 for the performance of ISI examinations on Reactor Building Purge Valves (AH-Vl A/B/C/D).
This action is effective by transmittal of this letter.
Therefore, relief from ASME Code requirements is not needed for this item.
GPUN intends to perform surface examination of the welds in these valves as required by this portion of the Code.
- A legible full size print of this drawing has been provided to the NRC Licensing Project Manager, John Thoma, and is not a part of this submittal. -
3.
No further clarification on this item was requested by the NRC during the conference call on September 16, 1986, 4.
The examinations involved in this request for relief are currently scheduled to be performed during the 1990 to 1991 timeframe.
GPUNC intends to qualify the adequacy of this ultrasonic examination technique to detect unacceptable flaws at both the ID and OD surfaces prior to use.
Due to constant improvements in ultrasonic equipment and techniques, and the anticipated release of Section XI procedure qualification guidelines, GPUN feels definition of specific qualification guidelines at a later date (approximately one year prior'to examination) may be more appropriate.
The results of this tcchnique qualification will be made available for NRC review. Therefore, this relief request is being withdrawn for administrative purposes at this time. However, we may refer to this request in later correspondence.
5.
Pursant to the requirements of 10 CFR 50.55a(g), we are advising the NRC of our intent to use portions or articles of later Code Publications.
GPUN intends to adopt the 1983 Edition with no Addenda, Article Paragraph IWB-2500, Table IWB-2500-1, Examination Category B-M-1, Item B12.30 for the performance of ISI examinations on valve RC-RV2.
Valve RC-RV2 is a 2-1/2" nominal diameter pilot operated relief valve for the Reactor Coolant System.
GPUN intends to perform surface examination of the welds in this valve as required by this portion of the Code. This action is effective by transmittal of this letter.
Therefore, relief from ASME Code requirements is not needed for this item.
6.
Pursuant to the requirements of 10 CFR 50.55a(g), we are advising the NRC of our intent to use portions or articles of later Code Publications.
GPUN intends to adopt the 1977 Edition with Addenda through Summer 1978, Article Paragraph IWB-2500, Table IWB-2500-1, Examination Categories B-H and B-K-1, Item Numbers B8.10, B8.20, 08.30, B8.40, B10.10 and B10.30 for the performance of ISI examinations on welded attachments. GPUN intends to perform surface examination of the integrally welded attachments equal to or greater than 5/8 inch in thickness as required by this portion of the Code. This action is effective by transmittal of this letter.
Therefore, relief from ASME Code requirements is not needed for this item.
7.
This request for relief involves 26 Main Steam System Welds and 4 Decay Heat Removal System welds all of which are Class 2 non-exempt.
These welds will be scheduled for examination as described in IWC-2520 and IWC-2411 of Section XI,1974 Edition with Addenda through Summer 1975.
The subject welds (see Figure 1) are of the standard " weld-o-let" design or as in the case of some of the main steam welds, they are of weld-o-let design with an adjacent reinforcing pad.
A typical weld-o-let design is shown in the attached Figure 1.
The design of this joint is such that ultrasonic examination from the branch side of the connection cannot be performed due to lack of space required to apply the transducer and due to a constantly changing contour.
Ultrasonic examination from the outside surface of the main pipe run would not be in the correct direction to detect service induced inside diameter flaws and would be less sensitive to outside diameter flaws than surface examination techniques. Also, in the case of welds with reinforcing pads, sound would be prevented from penetrating the required volume.
Radiographic examination of these welds is best performed with access to the inside of the piping.
But in this case, without access, less than optimum examination results would be obtained.
Surface examination only of these welds meets later editions of the Section XI Code (Summer 1978 and later) and Code Case N-408. Therefore, we feel that the alternate examination is justified and meets the intent l
of the ASME Code.
8.
No further clarification on this item was requested by the NRC during the conference call on September 16, 1986.
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