ML20236W120
| ML20236W120 | |
| Person / Time | |
|---|---|
| Site: | Byron  |
| Issue date: | 07/29/1998 |
| From: | Graesser K COMMONWEALTH EDISON CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| BYRON-98-0224, BYRON-98-224, NUDOCS 9808050092 | |
| Download: ML20236W120 (6) | |
Text
i Conunonu ralth IMmn Company ll> ron Generating Stanon 4 650 Nonh Gennan Churc h Road Hy ron,11. 61010 979 6 TclH15 B 45441 July 29,1998 Ltr:
BYRON-98-0224 File:
2.01.0700 f
U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001
Subject:
Second 10 Year Inservice Inspection Program Byron Station Relief Request 12R-11, Revision 2
" Alternative Rules for Insulation Removal at Bolted Connections in Systems Borated for the Purpose of Controlling Reactivity."
Byron Nuclear Power Station, Units 1 and 2 Facility Operating Licenses NPF-37 and NPF-66 NRC Docket Nos. 50-454 and 50-455 Referenct Letter from Robert A. Capra (NRR), to Oliver D. Kingsley (Comed) dated January 13,1998, transmitting the Safety Evaluation Report for ASME Section XI Relief Requests for the Byron Second 10 Year Inservice Inspection Program.
l By the letter referenced above, the NRC transmitted the Safety Evaluation Report (SER) for several ASME Section XI relief requests for the Byron Station Second 10 Year Inservice Inspection (ISI) Program. In this SER, Byron Station's request for relief concerning Class 2 and 3 systems was denied. In response to the NRC l
transmittal, Byron Station is submitting Revision 2 of Relief Request 12R-11,
" Alternative Rules for Insulation Removal at Bolted Connections in Systems Borated for the Purpose of Controlling Reactivity."
i j
The intent of Relief Request I2R-11 is to provide acceptable alternatives to inspection of bolted connections under IWA-5242(a)of ASME Section XI,1989 Edition. The s
relief request is applicable to bolted connections on ASME Class 1,2, and 3 piping b
systems that are borated for the purpose of controlling reactivity.
i 9900050092 900729 PDR ADOCK 05000454 P
PDR; (p:\\98byltrs\\980224. doc) l
l Ilyron Ltr: 98-0224 July 29,1998 Page 2 In the referenced transmittal, the NRC approved Relief Request 12R-11, Revision 1, as it apphes to ASME Class 1 systems. The NRC did not approve the relief request for ASME I
Class 2 and 3 systems on the basis that the frequencies provided were not acceptable. To j
address the issues related to inspection frequencies for ASME Class 2 and 3 systems, Ilyron Station submits the attached Relief Request 12R-11, Revision 2, for NRC review.
The alternate provisions for the inspection of ASME Class 1 piping remain unchanged.
llyron Station respectfully requests NRC review by March 1,1999 to facilitate inspections in the next Byron Unit 1 refuel outage, B1R09.
Please address any comments or questions regarding this matter to this office.
Sincerely,
~JBtd st/
K. L Graesser Site Vice-Pre.ident Byron Nuclear Power Station KLG/12/rp Attachment cc:
NRC Regional Administrator, RIII Senior Resident Inspector,13yron Office of Nuclear Safety,IDNS MichaelT. Anderson,INEL l
l l
(p:\\98byltrs\\980224. doc)
BYRON STATION UNITS 1 & 2 SECOND INTERVAL ISI PROGRAM PLAN - NRC SUBMITTAL RELIEF REQUEST 12R-11 (Page1of4)
COMPONENT IDENTIFICATION Code Class:
1,2 and 3
References:
IWA-5242(a)
Examination Category:
B-P, C-II, and D-A Item Number:
All item Numbers per Categories B-P, C-H, and D-A
==
Description:==
Alternative Rules for Insulation Removal at Bolted Connections in Systems Borated for the Purpose of Controlling Reactivity CODE REQUIREMENT 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."
BASIS FOR RELIEF Pursuant to 10 CFR 50.55a(a)(3)(i), reliefis requested on the basis that the proposed alternative would provide an acceptable level of quality and safety. Specifically, reliefis requested from the requirement to remove insulation at bolted connections for VT-2 examination coincident with system pressure testing at normal operating pressure.
The following Byron Station material control and procedure control programs, in conjunction with the Proposed Alternate Provisions, provide an acceptable level of quality and safety for bolted connections in systems borated for the purpose of controlling reactivity.
In response to NRC Generic Letter 88-05, Byron Station has established a program for Engineering to inspect all boric acid leaks discovered in the containment building and to evaluate the impact of those leaks on carbon steel or low alloy steel components. Any evidence ofleakage, including dry boric acid crystals or residue, is inspected and evaluated regardless of ASME Class, location or whether the leak was discovered at power or during an outage. Issues such as the following are considered in the inspection and evaluation:
- 1) Evidence of corrosion or metal degradation,
- 2) Effect the leak may have on the pressure boundary, l
- 3) Possibility of boric acid traveling alor.g the inside ofinsulation on piping, and
- 4) Possibility of dripping or spraying on other components. Based on this evaluation, Byron Engineering initiates appropriate corrective actions to prevent recurrence of the leak and to repair, if necessary, any degraded materials or components.
1595.00305.30000 Revision 2
IlYRON STATION UNITS 1 & 2 SECOND INTERVAL ISI PROGRAM PIAN - NRC SUBMITTAL RELIEF REQUEST 12R-11 (Page 2 of 4)
These evaluations ensure issues related to leakage on borated systems are addressed, including corrective actions necessary to eliminate the source ofleakage.
The ASME Section XI Code,1989 Edition, Tables IWC 2500-1 and IWD 2500-1, e
presently prescribe the performance of ASME Class 2 and 3 pressure tests (visual, VT-2) on a frequency of once per ISI inspection period. Byron Station maintains a work control program (Electronic Work Control System-EWCS) that controls the implementation of examinations to prescribed time limits. Using the EWCS system, predefines will be assigned to examinations of borated system bolted connections at a 36 month frequency.
The EWCS predefines provide a level of quality and safety that exceeds that of the ASME Section XI Code for ASME Class 2 and 3 bolted connections interval since the examinations will be completed on a more consistent frequency.
The ASME Section XI Code,1989 Edition, Table IWB 2500-1, presently prescribes the performance of ASME Class 1 pressure tests (visual, VT-2) on a frequency of once per ISI refuel cycle. Byron Station will perform the examination of borated system bolted connections at this frequency, thereby maintaining a consistent level of quality and safety as that prescribed by the ASME Section XI Code.
The following information is not directly related to the basis for relief [10CFR50.55a(a)(3)(i)],
however it represents hardship with performing the VT-2 examinations of borated system bolted connections coincident the systems at normal operating pressure. The issues are provided with this relief request as additional supporting information.
I Code Class 1,2 and 3 systems borated for the purpose of controlling reactivity are e
extensive and large systems covering many areas and elevations. Scaffolding is required to access many of the bolted connections. In addition, many of the bolted connections are i
located in difficult to access areas and in medium to high-level radiation areas. Insulation removal combined with scaffolding requirements will increase refuel outage duration, j
financial costs, personnel exposure, and generation of radwaste associated with performance of VT-2 examinations.
The VT-2 examinations of Class I systems, primarily the Reactor Coolant System (RCS) l piping and components that are located inside containment, are performed at plant Mode 3.
As required by IWB-5221, the RCS is at a normal operating pressure of 2235 psig. At Mode 3, the RCS temperature is approximately 557 "F. A significant portion of the Class 2 and 3 piping systems is also located in the containment and is VT-2 examined coincident with the Class 1 piping systems at plant Mode 3. Removal / reinstallation ofinsulation for Class 1,2 and 3 systems poses significant radiological considerations.
1595.00305.30000 Revision 2
r BYRON STATION UNITS I & 2 SECOND INTERVAL i
ISI PROGRAM PLAN-NRC SUBMITTAL l
RELIEF REQUEST 12R-11 (Page 3 of 4) l l
Performance of a VT-2 examination, removal / reinstallation ofinsulation, and e
assembly / disassembly of scaffolding at bolted connections under these ope ating conditions I
also present significant personnel safety considerations. At Byron Station, the Class 1 VT-2 examination, coincident with Class 2 and 3 examinations, is a refuel outage critical path activity with duration in the Byron refuel outage schedule of 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />. The activities associated with erecting scaffold to all of the bolted connection components and inspecting i
at operating pressure can add 4 to 5 days to this critical path activity. Therefore, in addition to the personnel safety and radiological considerations, insulation removal / installation and scaffolding assembly / disassembly will have considerable impact on the refuel outage duration and subsequent return to service of the unit.
PROPOSED AI, TERNATE PROVISIONS For ASME Class 1 systems borated for the purpose of controlling reactivity, a system inservice leakage test shall be performed in accordance with the frequency required in Table IWB-2500 without the remt 'I ofinsulation from the bolted connections. The requirements for inservice leak tests shall be aub...ented with a minimum 4-hour hold time at system normal operating pressure prior to the VT-2 visual examination to allow for leakage propagation from the insulation.
Additionally, the insulation shall be removed from insulated Class I bolted connections and a VT-2 examination shall be conducted, with the system depressurized. The frequency for these depressurized VT-2 inspections shall be in accordance with the system examination frequencies specified in Tables IWB-2500, Category B-P (each refueling outage). The proposed alternative is consistent with the requirements of Code Case N-533. These inspections shall be implemented through the application of the Byron Station predefined surveillance program to assure they are performed within the prescribed time periods.
For ASME Class 2 and 3 systems borated for the purpose of controlling reactivity, a system pressure test shall be performed in accordance with the frequency required in Tables IWC-2500 or IWD-2500, as applicable, without the removal ofinsulation from the bolted connections. The requirements for system pressure tests shall be augmented with a minimum 4-hour hold time at system normal operating pressure prior to the VT-2 visual examination to allow for leakage propagation from the insulation. Additionally, the insulation shall be removed from individual insulated Class 2 and 3 bolted connections and a VT-2 examination shall be conducted, with the system depressurized at an increased frequency. VT-2 examinations on each component will be performed on approximately 36-month frequency, which coincides with plant refueling outages, not allowing the period between inspections on individual components to exceed 45 months. This increased frequency for individual components is more restrictive than the " Periodic Frequency" prescribed by ASME Section XI for Class 2 and 3 systems described in Tables IWC-2500 or IWD-2500. These inspections shall be implemented through the application of the Byron Station i
1595.00305.30000 Revision 2 1
i.
BYRON STATION UNITS 1 & 2 SECOND INTERVAL ISI PROGRAM PLAN - NRC SUBMITTAL RELIEF REQUEST I2R-11 (Page 4 of 4) predefined surveillance program (EWCS) to assure they are performed within the prescribed time periods.
Regardless of whether a component is scheduled for examination or not, any evidence ofleakage, either while insulated or while deinsulated, will result in evaluations for corrective measures in accordance with IWA-5250 (as modified for Byron Station by approved Relief Request 12R-12).
PERIOD FOR WilICif REI,IEF IS RROUESTED Reliefis requested for the second inspection interve.1 for Byron Station Units 1 and 2.
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l 1595.00305.30000 Revision 2
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