ML20197D237

Transmits Request for Approval of Alternative Exam ISI-12, Per 10CFR50.55(a)(3)(i)(ii),for 1989 Edition of ASME Section XI,IWA-5242(a) for Class 1 Bolted Connections Inside Bioshield for Plant Refueling Outage 9

ML20197D237
Person / Time
Site:	Callaway
Issue date:	12/19/1997
From:	Passwater A UNION ELECTRIC CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
ULNRC-3703, NUDOCS 9712290011
Download: ML20197D237 (8)

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U.-.S'. Nuclear Regulatory Commission A 7 ATTN: Document Control' Desk

. Mail' Station.P1-137 Wasn'.ngton,'D. C. 20555-0001 Gentlemen: ULNRC-3703 CALLAWAY PIJGT DOCKET NUMBER 50-483 REQUEST FOR ALTERNATIVE EIANINATION REQUIREMENTS FOR s THE CALLAWAY PLANT INSERVICE INSPECTION PROGRAM PLAN i

References:

1) ULNRC-3255 dated August 18, 1995' 2)'NRC letter dated December ~20, 1995

3) ULNRC-3443 dated September 18, 1996 I

4) NRC letter dated October 3, 1996

5) NRC letter dated October 8, 1996 This letter transmits the request for approval of Alternative Examination ISI-12 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 Refueling

-Outage 9.

-This submittal provides an explanation of the hardship and unusual difficulty due to unnecessary man-rem exposure incurred from the removal of insulation from Class 1 components inside the bioshield on systems

borated for t.he purpose of controlling reactivity.

Please note that this request for an alternative examination differs from previous lsubmittals as its scope-is limited to the highest dose locations inside the bioshield for a single refueling outage. This

-submittal also provides proposed alternatives to the code-requirement-that would provide an acceptable level Lof.. quality and safety. Concurrently, U,nion Electric has been aggressively working with the ASME Section XI f i

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' Subcommittee since December, 1996 for the approval of a mn ,

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' Code Case.that would provide a similar alternative (ASME Section XI ISI #97-43). Subcommittee XI will

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vote on this item on April 30, 1998.

Refuel 9 is currently scheduled to begin April 3, 1998. Approval of this Alternative Exam is requested by March 15, 1998. If you have any que.stions concerning this information, please contact us.

Very truly yours, f

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Alan C. Passwater Manager - Licensing and Fuels MAR /WEK/

Attachment:

Alternate Examination ISI-12

-4 STATE OF MISSOURI ):

1 ss CITY OF ST. LOUIS )

Alan C. Passwater, of lawful age, being first duly sworn upon oath says that he is Manager, Licensing and Fuels i

(Nuclear) 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 behnif 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 bel,ief.

By Alan C. Passwa+er Manager, Licensing cad Fuels i i

Nuclear SUBSCR,IBED and sworn to before me this /fM7 day Ahnela-r 1997, of ,

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cc: .M. H.: Fletcher

' Professional 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 1

Callaway Resident Office.

U.S. Nuclear Regulatory Commission U 8201 NRC Road Steedman, MO 65077

_Barry C. Westreich (2)-

Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission I:. 1 White Flint, North, Mail Stop 13E16 11555 Rockville Pike Rockville, MD .20852-2738 Manager, Electric _ Department Missouri Public Service Commission P.O. Box 360 Jefferson-City, MO 65102 J

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ALTERNATIMEX AMINATION IST 12 (Page 1of 4)

COMPONENT FUNCTION '

Code Class: 1

Reference:

IWA 5242(a)

Exan ination Category: B-P ltem Numtiers: All item Numbrrs Listed Under Examination Categories B-P

Description:

Alternate Rules for Insulation Removal During IWA 5000 Pressure Tests at Bolted Connections in Systems Borated for the Purpose of Controlling Reactivity Component Ntnbers: Bolted Connections Listed in Table 1 CODE REOUIRFMFNTS ASME Section 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 visual examination VT.2."

BASTS FOR PROPOSED ALTERNATIVE Authorization is requested for a proposed alternative from the requirement 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 proposes a one-time alternate examination from the code requirements 4f of IWA-5242(a) for Callaway Refuel 9 on Class I bolted connections inside the bioshield. Union Electric 1 believes that removal of insulation at bolted connections during Refocl 9 on components inside the bioshield for the sole purpose of visual examination is impractical and will result in hardship and unusual difficulty for the reasons !isted below per 10CFR50.55a(a:(3)(i):

1 The visual VT-2 examination of the Reactor Coolant System (RCS) is performed following the majority of outage maintenance activities and just 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 of the examinations at cold shutdown is the only relief realized by the use of Code Case N533.

2) All Class I bolted connections listed in Table I were inspected without insulation in accordance with Code Case N533 during Refuel 8. None of the tmlted connections exhibited any evidence of degradation due to boric acid corrosion. Where boric acid residue was discovered and bolting removed, no corrosion or gross degradation due to intergranular stress corrosion cracking (IGSCC) was evident on the bolting material.

3) . Exposure for all examinations performed in accordance with Code Case N533 from Callaway Refuel 8 totaled 9.2 Person-Rem, with no evidence of degradation discovered. Dose rates for Refuel 9 are cxpected to be higher than in previous outages due to the Axial Offset Anomaly and fuel defects that

' Callaway is currently experiencing in its reactor core. The projected dose for the nine components listed in Table I for Refuel 9 is expected to exceed 7 Person-Rem. This is considered an excessive amount of dose relative to tne anticipated inspection results.

4) Differential thermal expansion occurs when insulation is removed from a bolted connection that creates a greater chance for leakage. When insulation is removed, the flanges expand at a rate greater th:m the 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 of leaking.

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- AI,TERNATIVE EXAMINATION ISI 13 (Page 2of 4)

5) Code Class I systems borated for the purpose of controlling reactivity are extensive and consist oflarge systems covering many areas inside the containment bioshield c,t multiple elevations. Scaffolding will be required to taess many of the bolted connections. In addition, many of the bolted connections are located in medium to high radiation areas. Insulation removal combined with scaffolding requirements will increase outage costs. Refuel 8 craft support of these inspections incurred $43,000 in additional costs despite the limited relief provided by Code Case N533, if the exrm were to be performed during the normal VT-2 between Modes 3 and 2 ascending, critical path time will be extended by several hours -

to accommodate the insulation installation and scaffold removal inside the bioshield wall and throughout containment after the examination is complete. Critical path cost is curren ly estimated at $207,000 per day.

Union Electric believes that the established Callaway programs described below in addition to the alternative exandaation proposed below, provide an acceptable level of safety and quality for bolted connections in systems borated for the purpose of contmiling reactivity per 10CFR50.55a(a)(3)'ii).

1) In response to NRC Generic Letter 88 05, Union Electric established a program to inspect all boric acid leaks dis; overed in the containment building and to evaluate the itmaet of those leaks on carbon steel or low alloy steel components. All evidence of leaks, including boric acid crystals or residue, is inspected and evaluated regardless of whether the leak was discovered at power or during an outage.

Issues such as the following are con:idered in the inspection and evaluation: 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 of insulation on piping, and 4) possibility or dripping or spraying on other components. Based on this evaluation, appropriate corrective actions are initiated to prevent reoccurrence of the leak and to repair, if necessary, any d: graded materials or components.

2) Ir addhion to the nondestructive examinations required by ASME Section XI, finion Electric has committed to the bolting examination requirements of NRC Bulletin 82-02. In accordance with thm Hulletin, at least two nondestructive examination techniques (e.g., ultrasonic, liquid penetrant, magnetic particle, or visual VT 1) are performed on bolted connections of the following components: Steam Generator primary manways, Pressurizer primary manway, Pressurizer safety velves, and a total of 22 Reac.or Coolant System isolation valves that are greater than 6" NPS. As a minimum, two nondestructive examination techniques are used whenever the bolted connection of one of the subject components is disassembled for maintenance or other inspection. These adr itional examinations ensure that degradation mechanisms such as Stress Corrosion Cracking or corresion do not go undetected in bolted connections critical tc ;eactor safety.

3) All bolted connections on Callaway's Class I borated systems inside the bioshield consist of SA-453 Grada 660 for s:uds and SA-194 Grade 6 or SA-453 Grade 660 for nuts. The stainless steels were designed to be corrosion resistant in corrosive applica: ions. rhit is substantiated for the 410 stainless stects (SA-194) by &acunrnts such as EPRI Report NP-5769 which attests to the resistance of stainless steels to boric acid corrosion. EPRI Report TR-104748 further confirms in section 7.2.1 that the 410 stainless steels are superior to the low alloy and carbon steel bolting materials. 410 stainless steel is an ecceptable 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 cracking. EPRI Report TR-104748 also Mentifies A-286 (SA-453) as a superior fastening material. The superalloy was designed for resistivity to acid corrosion environments due to its high nickel and chrome content and the inclusion of molybdenum specifically to inhibit inorganic acids such as boric acid. These materials have been further evaluated by material 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 l~tks and evaporation of the water) would not attack the bolting significantly and would be a marked improvement over low-alloy steel assemblies." To ensure that degradation mcchanisms in these metals

. AI/I7RNATIVE EXAMINATION 151-12 (Page 30f 4) are mitipted. Union Electric maintains a program at the Callaway Plant that controls materials (insulation, thread lubricant, boron, etc.) that may come in contact with safety related components, including bolting. This program ensures that impurities are not present in concentrations that would promote development of Stress Corrosion Cracking in stainless steel bolted connections. The only carbon steel bolted connections at the Callaway Plant on systems borated for the purpose of controlling reactivity inside the bioshield are Steam Generators Manways, Reactor Coolant Pump Bolting and Pressurizer Manways. These areas will be inspected with the insulation removed in accordance with Code Case N533.

4) During Refuel 8 Callaway verified the integrity of all Class I bolted connections during 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 after 12 years of service. Based on the material properties of these bolted connections, degradation is not anticipated during the subsequent 18 months.

The proposed Alternative Examination is requested for one-time use at Callaway during Refuel 9. This Alternative is not a request for use of Code Case N533 as its use has already been approved for Callaway by the NRC, PROPOSED AI,TERNATIVE EXAMINATION Bolted connections fabricated of materials resistant to boric acid corrosion in systems horated for the purpose of controlling reactivity shall receive a visual VT-2 examination during the system pressure tests of IWB-5000 and IWC-5000 with the insulation installed. If eviden: of leakage is detected, either by discovery of active leakage or evidence of boric acid crystals, the insilation shall be removed and the bolted connection shall be re-examined and, if necessary, evaluated in accordance with the corrective measures of Suharticle IWA-5250.

Carbon steel bolted connections within the Inservice Inspection boundaries will receive an inspection for boric acid residue with the insulation removed. In addition, a VT-2 inspection will be performed in accordance with ASME Section XI requirements with the insulation installed at normal operati .y pressure and temperature.

If insulation is removed for planned maintenance, repair, or other inspection at a bolted connection in a system borated for the purpose of controlling reactivity, a visual examination 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.

c ALTERNATIVE EXAMINATION ISI-12

. Table 1 Class 1 Bolted Connections that are h1Sulated on Systems borated for the purpose of Controlling reactivity, Component H See HComponent lype ll Desenptum X Stud Ma'enal X Nut Matenal BB8085 3" GEeVaNe RCS LOOP 3 XOVER LEG TO CVCS LTON 30 SA-453 CT 660 SA-194 Gr 6 BB894SA 10" Check Vane RCS LOOP 1 COLD LEG SI ACC CHECK SA-453 Gr 660 SA-453 Gr 660 B88948B 10" Check Valve RCS LOOP 2 COLD LLG SI ACC CHECK SA-453 Gr 660 SA-453 Gr 600 BB8948C 10" Check Vane RCS LOOP 3 COLD LEG SI ACC CHECK SA-453 Gr 660 SA 453 Gr 660 BB8948D 10" Check Vatve RCS LOOP 4 COLD LEG SI ACC CHECK SA-453 Gr 660 SA-453 Gr 660 BB8949A 10" Check Vane RCS LOOP 1 HOT LEG Si PMPS CHECK SA-453 Gr 660 SA-194 Gr 6 BB89498 10" Check Vane RCS LOOT 2 HOT LEG St PMPS CHECK SA-453 Gr 660 SA 193 Gr 86 BD8949C 10" Check Vane RCS LOOP 3 HOT LEG S1 PMP3 CHECK SA-453 Gr 660 SA 193 Gr B6 BB8949D 10" Check Vane RCS LOOP 4 HOT LEG St PMPS CHECK SA-453 Gr 6N) SA-193 Gr B6 Page 4 of 4