ULNRC-03988, Requests Approval of Alternative Exam ISI-12A Per 10CFR50.55a(a)(3)(i) & (II) for 1989 Edition of ASME Section IX,IWA-5242(a) for Class I Bolted Connections Inside Bioshield for RFO 10

Requests Approval of Alternative Exam ISI-12A Per 10CFR50.55a(a)(3)(i) & (II) for 1989 Edition of ASME Section IX,IWA-5242(a) for Class I Bolted Connections Inside Bioshield for RFO 10

ML20204J140
Person / Time
Site:	Callaway
Issue date:	03/19/1999
From:	Passwater A UNION ELECTRIC CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
ULNRC-03988, ULNRC-3988, NUDOCS 9903300011
Download: ML20204J140 (5)

Text

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Union Elzctric one Ameren Plaza 1901 Chouteau Avenue I PO liox 66149 l March 19,1999 st. louk, Mo 63166-6149 314GH3272 U. S. Nuclear Regulatory Commission ATTN: Document ControlDesk Mail Station PI-137 Washington, D.C. 20555-0001 Gentlemen: ULNRC-03988 DOCKET NUMBER 50-483 CALLAWAY PLANT UNION ELECTRIC COMPANY REQUEST FOR ALTERNATIVE EXAMINATION REQUIREMENTS FOR g

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_TIIE CALLAWAY PLANT INSERVICE INSPECTION PROGRAM PLAN

References:

1) ULNRC-3703 dated December 19,1997 N f#$[$# 2) NRC letter dated March 24,1998 UE This letter transmits a request for approval of Alternative Examination ISI-12A per 10CFR50.55a(a)(3)(i) and (ii) for the 1989 Edition of ASME Section XI, IWA-5242(a) for Class 1 bolted connections inside the bioshield for Callaway l Refueling Outage 10. ISI-12A requests a one-time extension ofISI-12, which was approved for Callaway Refueling Outage 9 (See Reference 1 and 2).

This submittal explains the hardship due to unnecessary man-rem exposure and the unusual difficulty associated with removing insulation from Class I components inside the bioshield on systems borated for the purpose of controlling reactivity. The scope of this request is limited to components inside the bioshield for a single refueling outage. The proposed altematives to the code requirements provide an acceptable level ofquality and safety.

AmerenUE has been aggressively working with the ASME Section XI Subcommittee since December 1996 for the approval of a Code Case that would provide a similar alternative (ASME Section XI ISI #97-43). It was expected at the time of submittal ofISI-12 (ULNRC-3703) that the Code Case would be finalized in 1998, however the committee process has taken longer than expected. We expect the

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Code Case to pass in 1999, but not in time for use dming our 10* Refueling outage in October 1999.

Refuel 10 is scheduled to begin October 1,1999. Approval of this Alternative Exam is requested by September 15,1999. Ifyou have any questions concerning this information, please contact us.

Sincerely,

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9903300011 990319 PDR ADOCK 05000403 #d M&M G PDR -

Alan C. Passwater Manager, Corporate Nuclear Services i DES /pir

Attachment:

Alternative Examination ISI-12A a subsidiary of Amaren Corporation

l STATE OF MISSOURI )  ;

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CITY OF ST. LOUIS )  ;

i Alan C. Passwater, of lawful age, being first duly sworn upon oath says that he is Manager, Corporate Nuclear Services for Union Electric Company; that he has read the foregoing document and knows the content thereof; that he has executed the same for and on behalf of said company with full power and authority to do so; and that the facts therein stated are true and correct to the best of his knowledge, information and belief.

By -

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Alan C. Passwater Manager, Corporate Nuclear Services 4

SUBSCRIBED and sworn to before me this ~ day of d '27 # M , 1999.

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PATRICIA L REYNOLDS ll0TARY PUBUC--6 TATE OF A8880UN ST. Louts COUNTY hlY004StSSION EXPlRES DEC.22,2000

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J cc: 'M. H. Fletcher

'Piofessional Nuclear Consulting, Inc.

19041 Raines Drive Derwood, MD 20855-2432 Regional Administrator U.S. Nuclear: Regulatory Commission Region IV 611 Ryan Plaza Drive Suite 400. '

Arlington, TX 76011-8064 Senior Resident Inspector Callaway Resident Office U.S. Nuclear Regulatory Commission 8201 NRC. Road Steedman, MO 65077 Mr. Mel Gray (2)

Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission 1 White Flint, North, Mail Stop 13E16 11555 Rockville Pike Rockville, MD 20852-2738 l

Manager, Electric Department ,

Missouri Public Service Commission .

P.O. Box 360 l Jefferson City, MO 65102 i

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ALTERNATIVE EXAMINATION ISI-12A (Page1of3) 1 COMPONENT FUNCTION Code Class: 1

Reference:

_ IWA-5242(a) ,

Exammation Category: B-P Item Numbers: All item Numbers Listed Under Exammation Categories B-P

Description:

. Alternate Rules for inadema Removal During IWA-5000 Pressure Tests at ;

Bolted Connecuens in Systems Borated for the Purpose of Controlling i Reactivity Ca==panant Numbers. Bolted Connections Listedin Table 1 CODE REOUIREMENTS ASME Secuon XI,1989 Edition, Paragraph IWA-5242(a) states, "For systems borated for the purpose of controlling reactivity, insulation shall be removed from pressure retaining bolted connections for sisual l examination VT-2."

i BASIS FOR PROPOSED ALTERNATIVE Authorization is requested for a proposed alternative from the reqmrement to remove insulation for visual VT-2 examination of bolted connections during a system pressure test on systems borated for the purpose  ;

of controlling reactivity. This request is for an extension of the previously approved request ISI-12 for  !

Callaway Refuel 10 only. 'this request is for a one-time exemption from the code requirements ofIWA-

$242(a) for Callaway Refuel 10 on Class 1 bolted connections inside the bioshield. l AmerenUE believes that removal ofinsulation at bolted connections during Refuel 10 on components msule the bioshield for the sole purpose of visual examination is impractical and will result in hardship and unumm1 ddficulty for the reasons listed below per 10CFR50.55a(aX3Xi):

1) The visual VT-2 examination of the Reactor Coolant System (RCS) is performed following the majority of outage maintenance activities andjust prior to reactor criticality. The RCS is at a normal operating temperature and pressure (557*F and 2235 psig) during the pressure test as required by IWA-5000.

Performance of a visual VT-2 examination, re-installation ofinsulation, and disassembly of scaffolding under these conditions is a personnel safety hazard. Performance oithe examinations at cold shutdown

' is the only relief realized by the use of Code Case N533.

2) All Class 1 bolted connections listed in Table I were inspected without insuiation in accordance with Code Case N533 during Refuel 8. None of the bolted connections exhibited any esidence of degradstion due to boric acid corrosion. Where boric acid residue was discovered ami bolting removed, no corrosion or gross degradation due to intergranular stress corrosion cracking (IGSCC) was evident on the botting material. Exposure for all examinations perforir_ed in accordance with Code Case N533 from Callaway Refuel 8 totaled 9.2 Person-Rem, wit h no evidence of degradation discovered. 'the projected dose for the nine components listed in Table I for Refuel 10 is expected to exceed 5.8 hrson-Rem. This is considered an excessive amount of dose relative to the anticipated inspection results.

3) Differential thermal expansion occurs when insulation is removed from a bolted connection tiet creates a greater chance for leakage. When insulation is remowd, the flanges expand at a rate greater than the

o ALTERNATIVE EXAMINATION ISI-12A (Page 2 of 3) bolts causing stress on the connection. Once the bolts expand, the stress has caused the equivalent of untorquing the connection. The less tightened connection then has a higher probability ofleaking.

4) Code Class I systems borated for the purpose of controlling reactivity are extensive and consist of large systems covering many areas inside the containment bioshield on multiple elevations.

Scaffolding will be required to access many of the bolted connections. In addition, many of the bolted connections are lacatM in medium to high radiation areas. Insulation removal combined with scaffolding requirements will increase outage costs. Refuel 8 craA support of these incpections incurred $43,000 in additional costs. These costs were incurred despite the limited relief prmided by Code Case N533. If the exam were to be performed dunng the normal VT-2 between Modes 3 and 2 ascending, critical path time will be extended by several burs to accommodate the insulation installation and scaffold removal inside the bioshield wall and throughout containment aAer the examination is complete. Critical path cost is currently estimated at $207,000 per day.

5) VT-2 exams on the listed components were performed with the inanimaion installed in accordance with Alternative Examination ISI 12 during Callaway Refuel 9. The inspections identified no leakmg connectsons at any of the listed components.

AmerenUE believes that the established Callaway piograms described below in addition to the alternative examination proposed below, pro ide an acceptable level of safety and quality for bolted connections in ,

systems borated for the purpose of controlling reactivity per 10CFR50.55a(a)(3)(ii). l 1

1) In response to NRC Generic Letu:r 88-05, AmerenUE established a program to inspect all boric acid i leaks discovered in the contamment building and to evaluate the impact of those leaks on carbon steel or low alloy steel components. All evidence of leaks, including boric acid crystals or residue, is kW and evaluated regard! css of whether the leak was discovered at power or during an outage.

Issues such as the following are considered in the inspection and enluation: 1) evidence of corrosion or metal degradation,2) effect the leak may have on the pressure boundary,3) possibility of boric acid traveling along the inside ofinsulation on piping, and 4) possibility of dripping or spraying on other c-:-4-:+ents. Based on this evaluation, appropriate corrective actions are initiated to prevent reoccurrence of the leak and to repair, if necessary, any degraded materials or components.

2) In addition to the nondestructive examinations required by ASME Section XI, AmerenUE has committed to the bolting examination requirements of NRC Bulletin 82 02. In accordance with this Bulletin, at least two nondestructive examination techniques (e.g., ultrasonic, liquid penetant, magnetic particle, or visual VT-1) are performed on bolted connections of the following components:

Steam Generator primary manways, Pressurizer pnmary manway, Pressunzer safety valves, and a total of 22 Reactor Coolant System isolation valves that are greater than 6" NPS. As a minunum, two  ;

nondestructive examination techniques are used whenewr the bolted connection of one of the subject components is disasserabled for maintenance or other inspection. 'Ihese additional examinations ensure that degradation mechanisms such as stress corrosion crackmg or corrosion do not go undetected in bolted connections critical to reactor safety. j

3) All bolted connections on Callaway's Class 1 borated systems inside the bioshield consist of SA-453 Grade 660 for studs and SA-194 Grade 6 or SA-453 Grade 660 for nuts. The stainless steels were i designed to be corrosion resistant in corrosive applications. 'Ihis is substantiated for the 410 stainless 1 steels (SA-194) by documents such as EPRI Report NP-5769 which attests to the resistance of stainless steels to boric acid corrosion. EPRI Report "1R-104748 further confirms in section 7.2.1 that the 410 stainicas steels are superior to the low alloy and carbon steel bolting materials. 410 stainless steel is an acceptable nut material as the nuts only experience a compressive stress. Tensile stresses are required for initiation of stress corrosion cracking. Therefore, only studs comprised of 410 stainless steel are potentially susceptible to stress corrosion crackmg. EPRI Report TR-104748 also identifies the A 286 (SA-453) as a superior fastening material. The superalloy was designed for resisthity to acid mrrosion environments due to its high nickel and chrome content and the inclusion of molybdenum specif.cally to inhibit inorganic acids such as boric acid. 'Ihese materials have been further evaluated by rsterial selection expert C.P. Dillon who was subcontracted by Nickel Laboratories. His evaluation concludes "the development of intermediate concentrations of boric acid solution in the flange area (due to minor leaks and evaporation of the water) would not attack the bolting significantly

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ALTERNATIVE EXAMINATION ISI-12A (Page 3 Of 3) and would be a marked improvement over low-alloy steel assemblies." To ensure that degradation mechanisms in these metals are mitigated, AmerenUE mainmins a program at the Callaway Plant that controls matenals (insulation, thread lubricant, boron, etc.) that may come in contact with safety related components, including bolting. 'Ihis program ensures that impurities are not present in concentrations that would promote development of Stress corrosion cruciang in stainless steel bolted connections. 'Ihe only carbon steel bolted connections at the Callaway Plant on systems borated for the purpose of controlling reactivity inside the bioshield are Steam Generator manways, Reactor Coolant Pump bolting and Pressurizer manways. 'lhese areas will be iaW for with the insulation r6 moved in accordance with Code Case N533.

4) Dunns Refuel 8 Callaway verified the integrity of all Class I bolted connections durmg cold shutdown with the insulation removed and during the normal VT-2 with insulation installed in accordance with Code Case N533 and no evidence of degradation was discovered aAer 12 years of service. Based on ine meternal properties of these bolted connections, degradation is not anticipated.

Use of the proposed akernative exammation is requested for one time use at Callaway Refuel 10. 'Ihis Alternative is not a request for use of Code Case N533 as its use has already been approved for Callaway by the NRC.

PROPOSED ALTERNATIVE EXAMINATION-Bolted connections fabricated of materials resistant to boric acid corrosion in systems borated for the purpose of controlling reactivity shall receive a sisual VT-2 exammation during the system pressure tests of IWB-5000 and IWC-5000 with the insulation installed. If evidence ofleakage is detected, either by discovery of active leakage or evidence of boric acid crystals, the insulation shall be removed and the bolt d connection shall be re-examined and, if necessary, evaluated in accordance with the corrective measures of Subarticle IWA 5250.

Carbon steel bolted connections within the Inservice Inspection bourderies will receive an inspection for j boric acid residue with the insulation removed. In addition, a VT-2 inspection will be performed in  !

accordance with ASME Section XI reqmrements with the insulation installed at normal operating pressure

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Ifinsulation is removed for planned maintenance, repair, or other inspection at a bolted connection in a system borated for the purpose of controlling reactisity, a visual exanunation shall be performed on the bolted connection prior to disassembly and, if evidence of leakage is discovered, evaluated in accordance with the corrective measures of Subarticle IWA-5250.

Table 1 Claes 1 Boted Connections that 4.te insulated on systems borated for the purpose of controlkng readivity Component Stre Component Type Doomtption Stud Matertel Nut Meterial 888005 3" Gote Velvr RCS LOOP 3 XOVER LEG TO CVCS LTDN SA-453 Gr Soo SA 194 Gr 6 1 888048A 10" Check Velve RCS LOOF 1 COLD LEG SI ACC CHECK SA453 Gr 600 SA-453 Gr 600 i 8809408 10' Check Velve RCS LOOP 2 COLD LEG St ACC CHECK SA-453 Gr 600 SA-453 Gr 600 888048C 10" Check Velve RCS LOOP 3 COLD LEG St ACC CHECK SA-453 Gr 600 SA-453 Gr 600 88804'o 10" Check Velve RCS LOOP 4 COLD LEG St ACC CHECK SA-453 Gr 600 SA-453 Gr 600 BB6340A 10" Check Velve RCS LOOP 1 HOT LEG S1 PMPS CHECK SA-453 Gr 600 SA-194 Gr 6 l B889408 10" Check Velve RCS LOOP 2 HOT LEG Si PMP.S CHECK SA-453 Gr 600 SA-453 Gr 600 BnN 10" Check Velve RCS LOOP 3 HOT LEG St PMPS CHECK SA-453 Gr 600 SA-453 Gr 600 i 888040D 10" Check Velve RCS LOOP 4 HOT LEG St PMPS CHECK SA-453 Gr 600 SA-453 Gr 600