ML20087E176

Submits Evaluation Procedure for Reactor Vessel Outlet nozzle-to-shell Weld Indication,Per IWB-3122.4 of ASME Section Xi.Flaws Acceptable.Continued Svc Warranted Based on Evaluation Results

ML20087E176
Person / Time
Site:	Point Beach
Issue date:	03/12/1984
From:	Fay C WISCONSIN ELECTRIC POWER CO.
To:	Harold Denton, John Miller Office of Nuclear Reactor Regulation
References
TAC-54446, NUDOCS 8403160054
Download: ML20087E176 (3)

Text

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F WlSCOnSin Electnc rana couesnr 231 W. MICHIGAN, P.O. BOX 2046, MILWAUKEE, WI 53201 March 12, 1984 Mr. H. R. Denton, Director Office of Nuclear Reactor Regulation U. S. NUCLEAR REGULATORY COMMISSION Washington, D. C. 20555 Atten tion: Mr. J. R. Miller, Chief Operating Reactors, Branch 3 Gentlemen:

DOCKET 50-266 REACTOR VESSEL OUTLET NOZZLE-TO-SHELL

})T.LD INDICATION EVALUATION PROCEDURE POINT BEACH NUCLEAR PLANT, UNIT 1 During Point Beach Unit 1 Refueling 11, an ultrasonic examination of the reactor vessel outlet nozzles was performed.

in accordance with ASME Boiler and Pressure Vessel Code Section XI. This examination was done to fulfill the first period requirements of the second ten-year interval. The second ten-year interval plan for Point Beach Nuclear Plant, Unit 1, was written to conform to the 1977 Edition of ASME Section XI with addcada through the summer of 1979. The examination is performed rerotely and from the inside bore of the nozzle.

Included in the inspection plan for this outage was an inspection of the nozzle-to-vessel shell weld, nozzle inside radius section, nozzle integral extension, and nozzle-to-pipe weld of both outlet nozzles. An examination of 100% of the vessel flange-to-shell weld was also done during the outage.

During the examination, indications were identified in the nozzle-to-shell welds of both outlet nozzles. These indications were recorded and sized in accordance with Regulatory Guide 1.150 and then evaluated against the standards provided in IWS-3000 of ASME Section XI. These indications were present during a previous examination in 1981 but were of lesser reflectivity. One indication in each outlet nozzle-to-shell weld exceeds the acceptable sizes listed in Table IWB-3512. The flaw indication located in the "A" outlet nozzle-to-shell weld which exceeds the acceptable size 8403160054 840312 t PDR ADOCK 05000266 P PDR gg

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Mr. H. R. Denton March 12, 1984 I

limits of Table IWB-3512 is in proximity to another individually acceptable indication. The evaluation.was performed by an

- individual who is certified Level III in ultrasonic testing.

These two indications fall within the root area of the weld. - It is our opinion and that of our consultant, Southwest Research

! Institute, that the indications are the result of weld slag.

It is our intention to demonstrate that the flaws are acceptable and continued service is warranted by evaluation:in i

accordance'with IWB-3122.4 of ASME Section XI. As required by .

IWB-3122.4, the areas containing the indications will be reexamined T in accordance with IWB-2420 (b) and (c). .

In accordance with ~IWB-3610 (b) , we are submitting for your concurrence our. procedure for evaluating the acceptability of the indications: ,

1. Demonstration'~of Acceptance by_ Evaluation i a. Evaluation based.on linear elastic fracture mechanics and ASME Section XI, Appendix "A" (1977/S79) :

(1) Flaw characterization: The critical' size flaw to be analyzed will be the largest' indication, which is located:in the "A" outlet nozzle at

] 104' azimuth. TheLflaw is' characterized as a longitudinal subsurface flaw with an aspect-ratio a/l = 0.32, and through thickness depth:

2a'= 1.24". Although a'second flaw is in proximity and may possibly fall 1in the same plane such that (al + a2) 1 (ae +1a e )/2 is not

- satisfied, it will be assumed that the smaller flaw' indication will not contributeThis' to the'assumption fatigue growth of the major. flaw.

is made based on the relative. sizes of and^' spacing between the two indications. The'second indication has a 2a-dimensi~on:of 0.1F'and~a'l-dimension of'O.2",Jthus,.itscarea is less'than.

1%.of the larger indication._. Additionally,.

the second' indication:is spaced at least 1.26" from-the' edge of the larger: flaw.. ,

4 (2) Integrity;of the ves'sellwith theLflaw indications

will be~ assessed for both the A?and C outlet'~

nozzles employing'the following-(a) End-of-life, predicted. flaw.

. (b)' Degraded. fracture toughness arising from-long-term ir' radiation.1 4

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-Mr. H. R. Denton March 12, 1984 3

(c) Normal, upset, emergency, and faulted load conditions.

(d) Acceptance criteria of IWB 3612:

! (i) For normal'and upset conditions:

Kl a/K11410 where K l a is the arrest i toughness and K1 is the maximum applied streus intensity factor for normal, upset, and test conditions.

(ii)' For emergency and faulted conditions:

.Klc/K1 E> d where Kle is the fracture toughness' based on crack initiation and K1 is the maximum applied stress '

intensity., factor.under emergency and faulted conditions.

(3) Advanced fracture mechanics:. If the evaluations performed in (2) above do not satisfy the.

acceptance criteria, then more detailed analyses will be performed. The' steps, as determined necessary, may include:

(a) Detailed nozzle stress analysis.

2 (b) Elastic-plastic fracture analysis using.

the J/T approach.'

(c) Refined flaw characterization.

(d) Enhanced inspection.

2. Submittal.of the evaluation analyses'of examination results as required by IWB-3125(b)^.

3. Reexamination in accordance with IWB-2420 (b) and L (c) .

l We arel proceeding.with the analysis as outlined above..

~

F Please advise us if you requirefany1further.information with respect-to your approval of this procedure ~.

kvery truly yours,'

..a

.Vice. President- uclearl Power C. W.-Fay'

-Copies to NRC Resident Inspector.

J. G.'.Keppler, Region'III >

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