ML20214J094

Safety Evaluation Supporting Util 870211 Request for Relief from Inservice Inspection Requirement of 1974 Edition Through Summer 1975 Addenda of Section XI of ASME Code

ML20214J094
Person / Time
Site:	Trojan File:Portland General Electric icon.png
Issue date:	05/18/1987
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML20214J084	List: ML20214J081 ML20214J094
References
TAC-64648, NUDOCS 8705270636
Download: ML20214J094 (4)

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ENCLOSURE j

SAFETY EVALUATION i REQUESTS FOR. RELIEF FROM INSERVICE IRSFECTION REQUIREMENTS l

. PORTLAND GENERAL ELECTRIC COMPANY .

TROJAN NUCLEAR PLANT

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DOCKET NO. 50-344 l

Introduction

- 1 By letter dated February 11, 1987, Portland Genera) Electric Company (the j licensee) requested relief for the Trojan Nuclear Plant from an inservice inspection',(ISI) requirement of the 1974 Edition thmugh Sumer 1975 Adden'da of Section XI of the ASME Code. . This report provides an evaluation of the licensee's request, supportina infomation, and alternative examination, as well as the staff's bases for granting this request pursuant to 10 CFR 50.55a(g). This request remains in effect for the first ten-year inspection-interval unless revised or modified prior to the end of the interval. The relief reouest is evaluated below.

Evaluation of Relief Request i

Category B-D: Presurizer Nozzle item Number B2.2: nozzle-to-vessel weld and nozzle-to-vessel inner radiused section.

Areas Subject to Examination The areas shall include the nozzle-to-vessel weld and adjacent areas as shown in Figure IWB-25000 of the ASME Code Section XI,1974 Edition through Sumer 1975 Addenda.

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Extent and Frequency of Examination l

The extent of examination of each nozzle shall cover 100% of the volume to be inspected as shown in Figure IWB-25000 These examinations are to be performed once during the inspection interval.

Method of Examination Volumetric.

Code Deviation Request Relief is requested to perform a partial (approximately 30 percent) volumetric examination of the pressurizer surge line nozzle-to-vessel weld and nozzle-to-vessel inner radius section during the first 10-year' inspection interval.

Licensee's Basis for Relief The original design of the pressurizer does not permit sufficient access to inspect the areas required by Figure IWB-25000 of the Code. The configuration of the pressurizer surge line nozzle and pressurizer heater cable penetrations is such that access to the weld and inner radius are restricted (see Figure B2.2 attached to the licensee's letter dated February 11,1987). The nozzle and heater cable penetrations interfere with the positioning of the ultrasonic transducer, preventing a thorough examination. Approximately 70 percent of the required volume cannot be examined to Code requirements. In view of the ,

restricted access, it is impractical (i.e., physically impossible) to perform an ultrasonic examination of 100 percent of the weld, tise of radiography was considered and also determined to be impractical because either the source or film would have to be inserted inside the pressurizer for which access is difficult and personnel exposures would be unacceptable. It is also not practical to modify this configuration to permit a greater percentaae of the volume to be examined.

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Alternative Examination Proposed I l

A volumetric examination will be perfomed of the accessible volume. The l results of this examination will be compared to the baseline examination results. The baseline examination was also a partial examination in which no indications were observed. In addition, the subject area was visually examined during performance of the first 10-year system hydrostatic pressure

test which was conducted in 1985.

Evaluation and Conclusions J

The configuration' of the pressurizer in the vicinity of the pressurizer surge line nozzles is such that access for examination of the surge line l nozzle-to-vessel weld and the adjoining base metal is restricted. The contour of the nozzle and nearby pressurizer heater cable penetrations limit the coverage of the required area that can be obtained by the ultrasonic 3 transducer. Examination of approximately 70 percent of the required area is unobtainable.

The licensee has considered using radiography to complete the required volumetric exariinations. This has been detemined to be impractical because either the film or the source would have to be placed inside the pressurizer.

This approach would result in much higher radiation exposure than would nomally be incurred by the ultrasonic examination method.

The licensee can complete examination of approximately 30 percent of the Code required volume. These examination results will be compared to the baseline results obtained during the preservice examination. If any degradation is taking place in the nozzle-to-vessel weld or adjoining base metal, it would likely be detected using the proposed alternative examination. Additional assurance of pressure boundary integrity is obtained by performance of the Code required hydrostatic pressure test each interval.

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_4 Based on the staff's evaluation and the licensee's discussion above, the staff has concluded that compliance with Code requirements is impractical. It is further concluded that the proposed alternatives will provide adequate assurance of early detection of flaws in the examination area and thus will provide an acceptable level of quality and safety. The staff, therefore, concludes that relief from the Code requirement may be granted as requested in accordance with 10 CFR 50.55a(g)(6)(1) and 10 CFR 50.55a(a)(3)(i).

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