ML20148T597

Forwards Requests for Inservice Insp Relief from ASME Section XI for Second 10-yr Insp Interval for Plant.Approval Requested by Sept 1988 to Allow Time Prior to Spring 1989 Unit 1 Refueling During Which Time Exams Scheduled.Fee Paid

ML20148T597
Person / Time
Site:	Point Beach
Issue date:	01/25/1988
From:	Fay C WISCONSIN ELECTRIC POWER CO.
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
CON-NRC-88-010, CON-NRC-88-10 VPNPD-88-056, VPNPD-88-56, NUDOCS 8802030345
Download: ML20148T597 (14)

Text

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WISCONSIN Electnc n.e comu 231 W WCHIGAN,P O Box 2046N1LWAukEE.WI 53201 (414)277 2345 VPNPD-88-056 l NRC-88-010 January 25, 1988 U.S. NUCLEAR REGULATORY COMMISSION Document Control Desk Washington, D.C. 20555 i

1 Gentlemen:

I 79CKETS 50-266 AND 50-301 CO M CTIQ. XI, RELIEP REQUESTS

{G_ INT BEACH NUCLEAR PLANT, UNITS 1 AND 2 In accordance with 10 CFR 50.55 a(g)(5)(iii), Wisconsin Electric Power Company (licensee) requests inservice inspection relief i

for the second ten-year inspection interval for Point Beach 7 Nuclear Plant, Units 1 and 2. Attachment 1 provides the suppor-tive information for the relief request from the 1977/ Summer, 1979 ,

Edition / Addenda of ASME Section XI code requirement to conduct a l Category B-L-1 and B-L-2 examinatica on a Unit I reactor coolant '

pump casing. Attachment 2 provides the supportive information for the relief request from the same requirements for Unit 2. Attach-

), ments 3 and 4 provide drawings of the Point Beach reactor coolant pumps. Wisconsin Electric requests that the Ccmmission review these relief requests and provide approval as required by the 1 Commissior's regulations.

We understand that relief requests similar to the attached have been previously approved for numerous licensees including Point i Beach Nuclear Plant, Unit 2. Therefore, we trust that your review and approval can be completed in a timely manner, but no later than September 1988. This will allow us sufficient planning time prict to the Spring 1989 Unit I refueling during which these examinations are scheduled. The Unit 2 examinations are currently scheduled for the Fall 1990 refueling outage. '

Enclosed is a check in the amount of $150 for the application fee required by 10 CFR Part 170.

Please contact us if any additional information is needed.

Very truly yours,

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8802030345 080125 PDR ADOCK 05000266

' / < G PDR C. W. Fay l Vice President j Nuclear Power 4

Attachments (Check 408999) C, g gjfgg,g j!/

Copy to NRC Resident Inspector g

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ATTACHMENT 1 UNIT 1 RELIEF REQUEST  !

Relief Request No. Description RR-1-13 Reactor Coolant Pump casing welds  !

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Component i Reactor Coolant Pump Exam Area l

Class 1 Casing Wolds l 1

Isometric or Component Drawing

• See Attachments 3 and 4.

l ASME Section XI Category l B-L-1 [

B-L-2 ASME Section XI I tem Numb _e_r_ ,

I B12.10 i B12.20 (

t ASME Section XI Examination Requirement (

B-L-1: "The examinations performed during each inspection  !

interval shall 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 t, coolant pumps)." The exam method shall be volumetric. [

t B-L-2: "One pump in each of the group of pumps performing similar functions in the system shall be (xamined during each inspection interval. This examination may be performed on the same pump selected for the category B-L-1 examina- t tion." The exam method shall be visual.

, Alternative Examin. tion A VT-2 examinatior. 'f ' ,e casing exterior is performed in conjunc-tion with the syst. ,aakagt test every outage and each system hydro test.

In addition, once es . 4aterval, an exterior surface examination of approximately 1/3 of the accessible pump casing weld surface will be conducted ln conjunction with a 100% exterior visual examination (VT-1).

Attachment 1 Page 1

If maintenance or operational problems are encountered which necessitate disassembly of the casing internals of either pump, a VT-3 examination of the interior casing surface will be performed.

Reason for Relief Request The two reactor coolant pumps (RCP) for Point Beach Unit 1 are Westinghouse Model 93 pumps. Each pump casing is fabricated by welding four stainless steel (SA351 CF8) castings together. Thus, there are 3 circumferential pressure-retaining welds that are to be volumetrically inspected in accordance with Category B-L-1.

Because the physical properties of the stainless steel castings and weld material prevent meaningful ultrasonic examination, the casing welds must be inspected using the miniature linear accel-erator (MINAC).

This radiographic examination is performed by placing the MINAC inside the pump casing and placing the film on the outside of the pump. To perform the examinatior, the pumps must be completely disassembled. Disassembly to this extent is far beyond any dis-assembly expected except for this examination. Also, insulation on the casing exterior must be removed for film placement. Addi-tionally, the pump bowl must be dry for installation of the MIdAC.

Therefore, all fuel assemblies must be removed from the reactor vessel and the vessel water level lowered to below the nozzles.

Complete disassembly of the pump is also required to conduct the VT-1 examination in accordance with Category B-L-2.

This radiographic examination using the MINAC was performed on Point Beach Unit 1 "B" RCP during the Fall 1981 refueling outage.

In addition, the same examination has been performed at several othcr sites. No problems have been found with the wolds at any site. Additionally, no problems have been found during the Category B-L-2 visual examination. This visual examination was conducted at PBNP by using the video camera on the MINAC.

We believe that performing a volumetric examination of the Point Beach Unit I reactor coolant pump casing welds and a visual exami-nation of the interior pressure retaining surface of one pump during the second ten-year inspection period does not provide an increase in safety commensurate with the associated cost potential for inadvertent pump damage, and expected radiation exposure. The following items have been considered:

1. Radiation Levels Currently the average dose rates at the PCP are 8' elevation general area < 1 - 25 mR/hr Below RCP ~10 - 800 mR/hr in RCP 700 - 10,000 mR/hr Attachment 1 Page 2

I 1

2. Total Estimated Exposure During The Examination

]

The whole body doses received during the fall 1981 examination of Unit 1, RCP-B are listed below. This list does not include the additional dose received while getting the plant to a

condition where RCP disassembly could be performed (e.g.,

complete core unload).

- PBNP maintenance personnel during disassembly 5,237 mR

- Contractor personnel - diffuser adapter removal 3,890 mn

- Contractor examination personnel 12,626 mR

' - Contractor personnel - insulation removal / replacement 4,490 mR

- Contractor personnel - diffuser adapter replacement 1,833 mR

- PBNP Maintenance personnel - reassembly 6,017 mR

! TOTAL 34,093 mR i

2

3. Pump Disassembly The Cat egory B-L-1 and B-L-2 examinations require complete disassembly of the pump. The pump manufacturer (Westinghouse)

I does not require or recommend pump disassembly to perform i normal maintenance or inspections. The only time disassembly

to this degree has over occurred was to perform this examina-tion during the fall of 1981. Therefore, very limited

experience in this area may result in significnat damage or

! degradation to the pump. Additionally, complete pump disassembly is not anticipated for any other reason in the foreseeabic future.

1

4. Pump Performance l

The type of material used in these pumps is widely used throughout the industry and has performed very well. There i

have been no reported problems or failures with the casing

- welds of those model pumps. Additionally, the licensee has

had no operational problems with the RCPs which could indicate potential degradation of the casing welds.

! 5. Excessive Cost

}

l The estimated cost to disassemble / reassemble the pump, remove and reinstall insulation and to perform the examination is approximately $810,000. Additionally, this examination is expected to extend the refueling outage a minimum of 5 days.

Therefore, replacement power costs would be a minimum of about S1.5 million. Any minor problems which might occur could i significantly increase the cost of the examination.

1 i

l Attachment 1 i Page 3

6. Alternative Examinations The alternative examinations we are proposing, as well as the already installed vibration monitoring system, will be sufficient to detect any problems which may occur.

a) A visual (VT-2) examination of the casing exterior is performed in conjunction with the system Icakage test every outage and each system hydro test. This examination will continue to be conducted.

b) Once each interval, an exterior surface examination of approximately 1/3 of the accessible pump casing weld surface will be conducted in conjunction with a 100%

exterior visual examination (VT-1).

c) If maintenance of operational problems are encountered which necessitate disassembly of the casing internals of either pump, a VT-3 examination of the interior casing surface will be performed.

d) Vibration monitors are currently installed on the motor frame near the lower radial bearing and on the motor shaft above the pump casing. These monitors will alarm on panel C04 in the control room if either detects high vibration. The PBNP Operating Procedures Manual provides RCP vibration limits. If the limi's are exceeded, we would expect to shut down and determine the cause. These monitors would most likely i detect any problem which could lead to pump casing, welds, or rotating element failure.

In conclusion, we believe that, based on the preceding items, performing the volumetric inspection of the RCP casing welds and the visual examination of the internal surface of the pump I

casings during the second son-year interval do not provide a l commensurate increase in safety. We, therefore, request approval of this relief request.

Attachment 1 Page 4 i

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.' ATTACHMENT 2 i i

UNIT 2 RELlEF REQUEST t h

Relief Request No. Description RR-2-13 Reactor Coolant Pump casing welds n

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! Reactor Coolant Pump Exam Area

! Class 1 Casing Welds Isometric or Component Drawing l See Attachment.

ASME Section XI Category B-L-1

B-L-2 i

a 1 ASME Section XI Item Number -

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! B12.10 j B12.20 j

l ASME Section XI Examination Re?.uirement i

B-L-1: "The examinations performed during each inspection interval shall include 100% of the pressure-retaining welds in at least one pump in each group of pumps performing similar fonctions in system (e.g. recirculating coolant pumps)." 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 examina-tion." The exam method shall be visual.

Alternative Examination A VT-2 examination of the casing exterior is performed in conjunc-tion with system leakage test every outage and each system hydro test.

In addition, once each interval, an exterior surface examination of approximately 1/3 of the accessible pump casing weld surface will be conducted in conjunctioc, with a 100% exterior visual examination (VT-1).

Attachment 2 Page 1

a If maintenance or operational problems are encountered which necessitato disassembly of the casing internals of either pump, a VT-3 examination of the interior casing surface will be performed.

Reason for Relief Request The two reactor coolant pumps (RCP) for Point Beach Unit 2 are Westinghouse Model 93 pumps. Each pump casing is fabricated by welding four stainless steel (SA351 CF8) castings together. Thus, there are 3 circumferential pressure-retaining wolds that are to be volumetrically inspected in accordance with Category B-L-1.

Because the physical properties of the stainless steel castings and weld material prevent meaningful ultrasonic examination, the casing welds must be inspected using the miniature linear accel-erator (MINAC).

This radiographic examination is performed by placing the MINAC inside the pump casing and placing the film on the outside of the pump. To perform the examination, the pumps must be completely disassembled. Disassembly to this extent is far beyond any dis-assembly expected except for this examination. Also, insulation on the casing exterior must be removed for film placement. Addi-tionally, the pump bowl must be dry for installation of the MINAC.

Therefore, all fuel assemblics must be removed from the reactor vessel, and reactor vessel water level lowered to below the vessel nozzles. Complete disassembly of the pump is also required to conduct the VT-1 examination in accordance with Category B-L-2.

This radiographic examination using the MINAC was performed on Point Beach Unit 1 "B" RCP during the Fall 1981 refueling outage.

In addition, the same examination has been performed at several other sites. No problems have been found with the welds at any site. Additionally, no problems have been found during the Category B-L-2 visual examination. This examination was conducted at PBNP by using the video camera on the MINAC.

We believe that performing a volumetric examination of the Point Beach Unit 2 reactor coolant pump casing welds and a visual exami-nation of the interior pressure retaining surface of one pump during the second ten-year inspection period does not provide an increase in safety commensurate with the associated cost potential for inadvertent pump damage and expected radiation exposure. The following items have been considered:

1. Radiation Levels Currently the average dose rates at the RCP are 8' elevation general area < 1 - 25 mR/hr Below RCP ~10 - 800 mR/hr in RCP 700 - 10,000 mR/hr Attachment 2 Page 2

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2. Total Estimated Exposure During The Examination The whole body doses received during the fall 1981 examination f

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of Unit 1, RCP-B are listed below. This list does not include the additional dose roccived while getting the plant to a j condition where RCP disassembly could be performed (e.g.,  !

complete core unload).

- PBNP maintenance personnel during disassembly 5,237 mR

- Contractor personnel - diffuser adapter removal 3,890 mR

- Contractor examination personnel 12,626 mR

- Contractor personnel - insulation removal / replacement 4,490 mR ,

- Contractor personnel - diffuser adapter l replacement 1,833 mR

- PBNP Maintenance personnel - reassembly 6,017 mR TOTAL 34,093 mR k

3. Pump Disassembly The category B-L-1 and B-L-2 examinations require complete  !

disassembly of the pump. The pump manufacturer (Westingheuse)  !

does not require or recommend pump disassembly to perform l normal maintenance or inspections. The only time disassembly t to this degree has ever occurred was to perform this examina- l tion during the fall of 1981. Therefore, very limited experience in this area may result in significant damage or degradation to the pump. Additionally, complete pump disassembly is not anticipated for any other reason in the  !

foreseeable future.

4. Pump Performance ,

i The type of material used in these pumps is widely used throughout the industry and has performed very well. These have been no reported problems or failures with the casing i welds of these model pumps. Additionally, the licensee has  !

had no operational problems with the RCPs which could indicate [

potential degradation of the casing welds.  !

I

5. Excessive Cost The estimated cost to disassemble / reassemble the pump, remove and reinstall insulation and to perform the examination is approximately $810,000. Additionally, this examination is expected to extend the refueling cutage a minimum of 5 days.

Therefore, replacement power costs would be a minimum of about

$1.5 million. Any minor problems which might occur could  ;

significantly increase the cost of the examination, i

Attachment 2 Page 3

6. Alternative Examinations The alternative examinations we are proposing, as well as the already installed vibration monitoring system, will be sufficient to detect any problems which may occur.

a) A visual (VT-2) examination of the casing exterior is performed in conjunction with the system leakage test every outage and each system hydro test. This examination will continue to be conducted.

b) Once cach interval, an exterior surface examination of approximately 1/3 of the accessible pump casing weld surface will be conducted in conjunction with a 100%

exterior visual examination (VT-1).

c) If maintenance of operational problems are encountered which necessitate disassembly of the casing internals of either pump, a VT-3 examination of the interior casing surface will be performed.

d) Vibration monitors are currently installed on the motor frame near the lower radial bearing and on the motor shaft above the pump casing. These monitors will alarm on panel C04 in the control room if either detects high vibration. The PBNP Operating Procedures Manual provides RCP vibration limits. If the limits are exceeded, we would expect to shut down and determine the cause. These monitors would most likely detect any problem which could lead to pump casing, welds, or rotating element failure.

In conclusion, we believe that, based on the preceding items, performing the volumetric inspection of the RCP casing wolds and the visual examination of the internal r.urface of the pump casings during the second ten-year interval do not provide a commensurate increase in safety. We, therefore, request approval of this relief request.

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