ML20028E136

Requests Relief from ASME Section XI Re Volumetric Exam of Reactor Coolant Pump Casing Welds & Visual Exam of Interior Surface of Pump Casing for First 10-yr Interval.Expedited Review of Waiver Requested

ML20028E136
Person / Time
Site:	Point Beach
Issue date:	01/13/1983
From:	Fay C WISCONSIN ELECTRIC POWER CO.
To:	Clark R, Harold Denton Office of Nuclear Reactor Regulation
References
TAC-49449, TAC-49450, NUDOCS 8301210019
Download: ML20028E136 (7)

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ntsconsin Elecinc mmcoww 231 W. MICHIGAN, P.O. BOX 2046, MILWAUKEE, WI 53201 January 13, 1983 Mr. H. R. Denton, Director Office of Nuclear Reactor Regulation U. S. NUCLEAR REGULATORY COMMISSION Washington, D. C. 20555 Attention: Mr. R. A. Clark, Chief Operating Reactors Branch 3 Gentlemen:

DOCKET NO. 50-301 ASME SECTION XI RELIEF REQUEST POINT BEACH NUCLEAR PLANT, UNIT 2 Mr. Clark's letter dated August 31, 1982 transmitted to '

Wisconsin Electric Power Comr,any (Licensee) license amendments 1 which revised the Technical Specifications for inservice inspections of safety-class components and granted relief from specific ASME Section XI code requirements. In our letter dated September 29, 1982 we addressed Mr. Clark's August 31 letter and submitted an additional relief request for both Units 1 and 2 at Point Beach Nuclear Plant. We stated that with the granting of this additional )

relief request and those previously submitted, the first ten-yaar inservice inspection interval requirements for Point Beach Unit 1 were complete. Also, we intend to complete all the first interval inservice inspection requirements for Unit 2 during the spring I refueling outage in 1983.

Included in the first ten-year inservice incpection items remaining to be completed for Unit 2 are the volumetric examination '

of one reactor coolant pump casing weld and a visual examination of the interior surface of the pump casing. As stated in our April 14, 1982 letter, which provided information regarding inservice inspection of reactor coolant pumps, we stated that before we performed the aforementioned examinations on a Unit 2 reactor coolant pump, an evaluation of the overall cost versus benefit of the examinations would be conducted. The casing weld examination for Point Beach Unit 1 required about 25 days to perform, including the associated pump disassembly and reassembly time, resulted in a total accumulated exposure of 36 man-rem, and a cost of about

$700,000. Based on the lower expected radiation exposure rates in Unit 2, the experience gained by performing the same examination at 8301210019 830113 '

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Y Mr. H. R. Denton January 13, 1983 a-total of four plants and improvements'made to the i.ispection equipment, the estimated time, exposure, and cost to perform the examination on a Point Beach Unit 2 reactor coolant pump are 18 days, 25 man-rem, and $500,0CC respectively.

It is Licensee's conclusion that performing this i examination on Unit 2 for the--first ten-year. interval does-not provide a commensurate increase in safety and, therefore, we request acceptance of the attached relief. request. This '

conclusion is based on the following points, which are also discussed in the relief request:

1. Overall costs, time, exposure, and financial resources are high.

2. No problems with the casing welds have been identified during the examination of four identical pumps.

3. The examination was performed on Point Beach Unit 1, which is an essentially identical unit, with no ,

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problems identified.

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! 4. Florida Power and Light, which has a similar situation l

at their Turkey Point Units 3 and 4, was granted a waiver of this inspection requirement for the second of the two identical units.

Since Unit 2 completed ten years of commercial operation l

on September 30, 1982, the reactor coolant pump examination must be performed during the 1983 refueling outage in order to fall within the first ten-year interval grace period if relief is not granted.

The 1983' refueling outage is scheduled to begin on March 25, 1983, thus, an expedited review of this waiver is requested.so that if relief is not granted, sufficient time exists to prepare for and perform the inspectien.

Very truly yours, -

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hb()} lt S Vice President-Nuclear Power C. W. Fay Enclosure Copy to NRC Resident Inspector

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ASME SECTION XI RELIEF REQUEST POINT BEACH NUCLEAR PLANT, UNIT 2 COMPONENT Reactor Coolant Pump ISOMETRIC OR COMPONENT DRAWING See attachment.

ASME SECTION XI CATEGORY B-L-1 and B-L-2 1974 Edition, Summer 1975 Addenda ASME SECTION XI ITEM NUMBER B5.6 and B5.7 1974 Edition,-Summer 1975 Addenda ASME SECTION XI EXAMINATION REQUIREMENT B-L-1: " T' ainations performed during each inspection interval ;hati include 100% of the pressure-retaining welds in at least one pump in each group of pumps performing similar functions in system (e.g. recirculating coolant pump s ) . " The exam method shall be volumetric.

B-L-2: "One pump in each of the group of pumps performing similar functions in the system shall be examined during each inspection interval. This examination may be performed on the same pump selected for the category B-L-1 examination."

The exam method shall be visual.

ALTERNATIVE EXAMINATION None.

REASON FOR RELIEF REQUEST j The Point Beach Unit 2 reactor coolant pumps are Westinghouse Model 93 controlled 1cakage pumps and are identical to the pumps in Point Beach Unit 1 and the pumps at the R. E. Ginna The plant, Turkey Point Units 3 and 4, and H. B. Robinson Unit 2.

Model 93 pump casing is fabricated by welding four stainless steel castings together. Thus, there are three circumferential pressure boundary welds in the pumps that are to be inspected in accordance with Category B-L-1.

It has been recognized since the installation of these pumps that a volumetric examination of the casing welds was not possible with existing ultrasonic techniques in the field.

The physical properties of the stainless steel casting and weld metal prevented a meaningful ultrasonic examination.

Thus, the capability to inspect these pump casing welds in the field did not exist until recently. In the spring of 1981 an examination was performed on one of the reactor cool &nt pumps at the R. E. Ginna plant using the miniature linear accelerator (MINAC), which was built ander an EPRI sponsored program. This equipment has been made available to other utilities, and currently constitutes the only method available for the inspection of reactor coolant pump casing welds.

The volumetric examination method is radiographic and is performed by placing the MINAC inside the pump casing and placing film on the outside of the pump. To perform the examination the pump must be completely disassembled, including removal of the diffuser adapter and the casing adapter. This amount of disassembly is far beyond the amount of disascembly performed for normal maintenance. Insulation must also be removed from the exterior of the pump casing. In addition, because the pump bowl must be dry for installation of the MINAC, a complete core unload is required.

The examination has been performed at four different sites, all of which have the Westinghouse Model 93 pump. The MINAC examination was performed at Ginna in the spring of 1981, at Point Beach Unit 1 in the fall of 1981, at Turkey Point Unit 3 early in 1982, and at H. B. Robinson Unit 2 later in 1982. No problems with the welds were found at any of the sites. A review of the original radiographs of the Point Beach Unit 1 pump was performed prior to the MINAC examination, and all the landmarks found were identified during the field examination with no apparent change.

The successful performance of this volumetric examination using the MINAC at four different sites demonstrates that the method is capable of satisfying ASME,Section XI, inspection requirements, however, the performance of the examination has shown that there is a relatively high radiation exposure associated with it. The total exposure associated with insulation rer. oval, disassembly, inspection, and reassembly of the pump has averaged about 40 man-rem.

There have been no weld defects identified by the four inspections performed on these pumps to date.

We, therefore, believe that performing a volumetric examination of the Point Beach Unit 2 reactor coolant pump casing welds and a visual examination of the interior pressure retaining surface of one pump during the first ten-year inspection

interval does not provide an increase in safety commensurate with the associated radiation exposure required to perform the examination. The inspection of a reactor coolant pump at Point Beach Unit 1, an identical unit, along with the inspection of three other identical pumps at other plants, provides reasonable assurance that no problems would be expected with respect to the Point Beach Unit 2 reactor coolant pump casing welds.

Based on the preceding factors we hereby request relief from performing a volumetric examination of the reactor coolant pump casing welds and visual examination of the interior pressure retaining surface of one of the two reactor coolant pumps at Point Beach Unit 2 during the first ten-year inservice inspection interval.

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