ML20069C292

Requests Relief from ASME Section XI Requirement for Volumetric Exam of Reactor Vessel Nozzle Welds Until End of 10-yr Insp Interval.Visual Insp of Interior Vessel Cladding Will Be Performed During Upcoming Refueling Outage

ML20069C292
Person / Time
Site:	Crystal River
Issue date:	03/14/1983
From:	Westafer G FLORIDA POWER CORP.
To:	Harold Denton Office of Nuclear Reactor Regulation
References
3F-0383-17, 3F-383-17, TAC-49790, NUDOCS 8303170492
Download: ML20069C292 (9)

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%%%UY Florida Power C O n c o n a i e o se March 14,1983 3F-0383-17 Mr. H. R. Denton, Director Office of Nuclear Reactor Regulation Attn: Document Control Desk U. S. Nuclear Regulatory Commission Washington, D. C. 20555

Subject:

Crystal River Unit 3 Docket No. 50-302 Operating License No. DPR-72 Relief from ASME Section XI, Article IWB-2000

Dear Mr. Denton:

The current inservice Inspection Program at Crystal River Unit 3 is based upon ASME Section XI,1974 Edition through Summer 1975 Addenda.

This letter requests relief from Article IWB-2000, Table IWB-2500, item B-D, " Full Penetration Welds of Nozzles in Vessels" of ASME Section XI,1974 Edition. This item requires a volumetric examination of the welds of nozzles in the reactor vessel. The 1974 Edition, paragraph IWB-2411, requires at least 25% of the nozzle inspections be completed by 31/3 years following the initial startup and 50% of the inspections be completed by 6 2/3 years.

In 1978, two of the six reactor vessel nozzles were thoroughly examined as described in the enclosed June 22,1978, letter. This extensive examination tevealed no rejectable defects.

Thus, tha required 25% of the nozzles have been inspected as required by the code.

Continued compliance with the 1974 Edition requirements would require Florida Power to lease very costly ($75,000 to $100,000) ultrasonic equipment to perform two reactor vessel nozzle inspections. This inspection would also require significant personnel exposure (approximately 20 man rem). Finally, inclusion of this inspection into the Refuel IV schedule is expected to increase the total outage by several days. With due consideration given to the fact that Florida Power will be inspecting all remaining nozzles at the completion of the 10 year inspection interval and to the cost of performing tlaese inspections twice (economically and radiologically), this requirement is considered overly restrictive. Thus, Florida Power requests that the remaining reactor vessel nozzle inspections be deferred MDl

/7 until the end of the 10 year inspection interval.

Florida Power Corporation does plan to perform a visual inspection of the interior vessel cladding which includes the interior of the nozzle to vessel weld in accordance with ASME Section XI during the upcoming refueling outage.

830317'o49 f)DRADOCKOhochh PDR General Office azui n.s.rtourtn street south. P O Box 14042, St. Petersburg. Flonda 33733 813--866-5151

i 3F-0383-17 March 14,1983 This relief request supersedes our relief request dated February 21, 1983. Florida Power asks that your response to this relief request be included with respect to previous Inservice Inspection re!!ef request responses scheduled to be issued by your staff on or about April 29, 1983.

Florida Power Corporation has determined that this relief request involves a Class Ili amendment, per 10CFR120.22, in that it involves a single safety issue. Accordingly, the fee of four thousand dollars ($4,000.00) will be forwarded under separate cover letter.

Sincerely,

. G. R. Westafer Manager Nuclear Licensing and Fuel Management PGH/ caw Enclosure

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cc: Mr. J. P. O'Reilly, Regional Administrator Office of Inspection & Enforcement U. S. Nuclear Regulatory Commission 101 Marietta St. N.W., Suite 2900 Atlanta, GA 30303

Babcock &Wilcox uw eco,troceo co,n,.ny g Copley, Ohio 44321 Teleph one:(216) 666 8841 June 22, 1978 1

Mr. Guy P. Beatty Nuclear Plant Superintendent Florida Power Corporation P. O. Box 1228 -

Crystal River, FL 32629 _

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Attention: S.W. Johnson REF: 192-072-007

SUBJECT:

Reactor Vessel Inlet Nozz.r.e--Examiriktion .

Dear Mr. Beatty:

In performing the examinations on two inlet nozzle-to-vessel welds on the Crystal River 3 reactor vessel, the examination plan called for only a single scan of this weld from the bore of the nozzle. This scan called for the ultrasonic beam to be normal to the bore interface over the length of taper between the inside and outside surfaces of the vessel. This was O chosen based on performing the examination at another facility which has a low angle taper in the bore and a different nozzle-to-vessel weld design. -What was an exception became the standard.

The baseline examination on the Crystal River 3 vessel had revealed indications in one of the inlet nozzles. The base-line examination had been performed with the ultrasonic beam ,

essentially normal to the weld axis. This was accomplished i by providing a slight angle of incidence to the wall of the nozzle to refract the beam normal to the weld. The original inservice examination was off this angle by the angle of the bore (150). Sufficient energy was not returned by any of the reflectors to detect the indications. -

Upon invest'igation of the reasons for not detecting the reflec-tors, it was discovered that neither examination fully covered the entire examination volume due to the curvature of the vessel at the 3 and 9 O' clock positions and between these points on the nozzles. The normal illustrations used to represent the nozzle-to-vessel weld usually show the intersection at 12 and 6 O' clock positions where vessel curvature is not a problem.

O .

The Babecck & Wifc:x Cornpany P wer Generation Division

. Babcock &Wilcox Mr. Guy P. Beatty ~2- June 22, 1978

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The examinations from the bore should have included the two prior described angles as well as a 300 angle to the weld to pick up the remaining volume. This is illustrated in Figure 1 where the angles are shown for an outlet and inlet nozzle.

All three angles are needed to completely scan the examination volume. At Crystal River, the initial evaluation showed that a sufficient beam path might not be available to calibrate to the depth of the examination volume from inside the bore for the 30 degree angle. It was decided to cover this area by using 45 and 60 degree beams from inside the vessel-normal to the weld using the nozzle belt vessel calibration block.

The examinations subsequently performed on two (2) inlet nozzles include four separate scans of the nozzle-to-vessel weld. The originally planned examinations included a normal ,

scan to the nozzle taper which results in a beam intersecting the weld at 15 degrees off the weld centerline plare due to the nozzle taper. This examination was determined to be in-sufficient to cover the inlet nozzle-to-vessel weld since the inside radius of the nozzle screens the internal wall portion of this weld. The reexamination of this weld included a longi-tudinal beam directed normal'to weld centerline plane plus a 45 and 60 degree angle beam directed at the weld centerline O plane from inside-the. surface of the vessel. These latter examinations cover the portion of the weld missed in the normal to nozzle taper examination.

The results of the original examination at a 15 degree angle to the weld did not reveal any of the three (3) indications originally found in the baseline examination of the inlet nozzle-to-vessel weld between the Z-W axes of the vessel. The subsequent examination with the normal to weld beam revaaled two (2) indications which exceeded 50 percent of reference level and seven (7) other indications which exceeded 20 per-cent of the reference level. The three (3) baseline indications exceeded the reference level with the largest being 125 per-cent. All indication defect dimensions are acceptable to the defect standards of the 1974 Section XI Edition including addenda thr'ough Summer 1975.

The indication locations from the baseline are plotted in Figure 2. The reference system used in the first automated system (ARIS-I) for nozzles had 0 degrees at the top of the nozzle and proceeded clockwise to 3600 at the zero position.

The three (3) indications w re e located at 13.3, 247.9, and 284.0 degrees as shown in Figure 2. The calibration block used for these examinations was 40705, a block mounted adjacent

.([) to the nozzle arm.

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, Babcock &Wilcox

(]} Mr. Guy P. Beatty June 22, 1978 For the update to the 75 Summer Addenda, a new calibration block was fabricated. This block (40757) was from a heat of A 508-64 Class 2 material (nozzle dropouts) while the base- i line block was plate material. This calibration block had longer beam paths for calibrations from the nozzle bore and t vessel flange and was the same material as in the vessel. ,

The nine indication locations on the nozzle for the inservice i

examinations are shown in Figure 2 for the reference system used on the second generation automated inspection device, ARIS-II. This system uses a different reference system with 0 degrees at the bottom of the nozzle and clockwise rotation being degrees positive and counterclockwise being degrees negative; 180 degrees positive and negative are the same point on the top of the nozzle. The nine (9) indications, detected are plotted in Figure 2 along with a smaller indica-tion. The location of the indications exceeding 20% DAC are

-167. 9; -13 0.1, -124. 3, -8 7, -47, +47. 4, +70. 4, +85. 8, and -

130.3 degrees with a 15% DAC indication at 104 degrees. This i

latter indication was found after the 20% indications were plotted and no indications appeared corresponding to this reference location. Although the reference level of the

(]) indications vary from baseline to inservice, the locations of baseline indications are confirmed with indications located which correspond to the same positions. However, the inservice indications do not correspond in amplitude with the baseline readings. Indications on the baseline and inservice inspections are located in depth near the root of the weld near the mid i plane. Figure 1 illustrates the weld preparation.

In the operation of the nozzle arm on the ARIS-I device, no provision was available for maximizing the beam angularity perpendicular with the calibration holes. This provides the possibility of the examination to be overly sensitive, but on the conservative side. The feature to maximize the calibration

' hole indication on the ARIS-II device is included. We.believe that this feature accounts for the difference in sensitivity between the. baseline and inservice examinations.

The 45 and 60 degree subsequent inservice examinations to cover the inner portion of the weld are illustrated in Figure 3.

Only one small indication was detected with these angle beams and it was acceptable.

All indications were calculated to be within the acceptance standards of Section XI. In addition, 20% to 20% DAC lengths 1

and through-wall dimensions of the indications were used in

. calculating acceptability and these dimensions were also acceptable.

o .

l Babcock &Wilcox g Mr. Guy P. Beatty June 22, 1978 The changes in calibration blocks and equipment have resulted in the differences observed.

If you have any questions, please contact me.

Sincerely yours,

[

. Frank JL attler, Manager Inservi Inspection FJS: ems Enclosures cc: R.L. Allison C.R. Honeycutt -

C.D. Thompson bcci M.D. Anderson E.G. Blackstone T.F. McDermott O R.A.

L.W.

Michalski Syverson G.A. Terning F.G. Whytsell 9

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g TOP VIEW OF NOZZLE 3'AND 9.O' CLOCK POSITIONS N

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,o 33 ,,, GENERAL VIEW OF RV INLET NOZZLE OUTLET AND INLET TO RADIUS VESSEL WELDS MEASURED -

NORMAL TO WELD CENTERLINE O

. o' as' SIDE VIEW OF NOZZLE N

6 AND 12 O' CLOCK POSITIONS a .

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O FIGURE 1 -

ILLUSTRATION SHOWING ANGLES NEEDED TO COVER NOZZLE-TO-VESSEL WELD ON B&W 177FA VESSELS

O BASELINE CLOCK INSERVICE ARIS I POSITION ARIS ll (DEGREES (DEGREES) 360 --

0 12 + 180 - - 180 ii 13.5

• n - 167

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-.- 30 1 -- - 150 a - 130.1 a9

-- 60 2 --

" - 120 al

-- 90 3 -- - 90

" - 87 a8 12 0 4 -- - 60 a - 47 a7 150 5 -- - 30 180 6 --

~0 0 - - 210 7 -- + 30

', , + 47.4 e6

- 240 8 -- + 60 a 247

• n + 70.4 e5

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+ 85.8 a4

-- 270 9 ." - + 90 a 284

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- - 300 10 -- + 120 a + 130.3 a3

- - 330 11 -- + 150 0 -- 360 12 - 180 -- + 180 COMPARISON OF BASELINE AND INSERVICE INDICATIONS FOR THElR RELATIVE CLOCK POSITIONS IN INLET NOZZLE BETWEEN Z.W AXES.

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OP VIEW OF NOZZLE 3 AND 9 O' CLOCK POSITIONS AREA SCANNED WITH '

45 & 60 DEGREE ANGLE BEAMS INCLUDES 1T OUTBOARD OF WELD, SKETCH NOT TO SCALE _ __ _ _

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SIDE VIEW OF NOZZLE

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FIGURE 3 -

ILLUSTRATION SHOWING ANGLE BEAM COVERAGE FROM INSIDE THE VESSEL ON THE NOZZLE-TO-

-VESSEL WELD

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