ML17291A836

SER Granting Relief for Requests on Interim Basis Until NRC Has Completed Comprehensive Review of Util Inservice Insp Program for Second ten-year Interval

ML17291A836
Person / Time
Site:	Columbia
Issue date:	06/01/1995
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML17291A835	List: ML17291A834 ML17291A836
References
NUDOCS 9506140337
Download: ML17291A836 (17)

Text

~4 0

~ Cy 0

C O

+a*++

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION OR SECOND 10-YEAR NTERVAL INSERVICE INSPEC ION RELIEF RE UESTS ASHINGTON PUBLIC POWER SUPPLY SYSTEH WPPSS WPPSS NUCLEAR PROJECT NO.

2 WNP-DOCKET NO. 50-39

1. 0 INTRODUCTION The Technical Specifications for WNP-2 state that the inservice inspection of the American Society of Hechanical Engineers (ASHE) Code Class 1, 2, and 3

components shall be performed in accordance with Section XI of the ASHE Boiler and Pressure Vessel Code and applicable Addenda as required by 10 CFR 50.55a(g),

except where specific written relief has been granted by the Commission pursuant to 10 CFR 50.55a(g)(6)(i).

Section 55a(a)(3) of Title 10 of the Code of Federal Regulations states that alternatives to the requirements of paragraph (g) may be used, when authorized by the NRC, if (i) the proposed alternatives would provide an acceptable level of quality and safety or (ii) compliance with the specified requirements would result in hardship or unusual difficulties without a compensating increase in the level of quality and safety.

Pursuant to 10 CFR 50.55a(g)(4),

ASHE Code Class 1, 2, and 3 components (including supports) shall meet the requirements, except the design and access provisions and the preservice examination requirements, set forth in the ASHE Code,Section XI, "Rules for Inservice Inspection of Nuclear Power Plant Components,"

to the extent practical within the limitations of design,

geometry, and materials of construction of the components.

The regulations require that inservice examination of components and system pressure tests conducted during the first ten-year interval and subsequent intervals comply with the requirements in the latest edition and addenda of Section XI of the ASHE Code incorporated by reference in 10 CFR 50.55a(b) on the date twelve months prior to the start of the 120-month interval, subject to the limitations and modifications listed therein.

The applicable edition of Section XI of the ASHE Code for the WNP-2 second 10-year inservice inspection (ISI) interval is the 1989 Edition.

Pursuant to 10 CFR 50.55a(g)(5), if the licensee determines that conformance with an examination requirement of Section XI of the ASHE Code is not practical for its facility, information shall be submitted to the Commission in support of that determination and a request made for relief from the ASHE Code requirement.

After evaluation of the determination, pursuant to 10 CFR 50.55a(g)(6)(i),

the Commission may grant relief and may impose alternative requirements that are determined to be authorized by law, will not endanger life, property, or the common defense and security, and are otherwise in the public interest, giving due consideration to the burden upon the 950bi40337 950bOi PDR ADOCK 05000394 l

PDR

licensee that could result if the requirements were imposed.

In a letter dated December 27, 1994, the Washington Public Power Supply System (licensee) submitted to the NRC its second ten-year inspection program plan and several requests for relief associated with its second ten-year interval inservice inspection program plan for the WNP-2.

2.0 gvVAIUAT Og The second ten-year inspection program plan is being reviewed by the NRC contractor Idaho National Engineering Laboratory, and a safety evaluation on its acceptability will be provided at a later date.

The staff's evaluation of the information submitted by the licensee in support of its second ten-year interval inservice inspection requests for relief for WNP-2 follows.

1.

Re uest for Relief 2ISI-05 IWD-5223 f Pressure Testin Pi in Downstream of Hain Steam Relief Valves Code Re uirement:

IWD-5223(f) requires that for safety or relief valve piping which discharges into the containment pressure suppression

pool, a pneumatic test (at a pressure of 90 percent of the pipe submergence head of water) that demonstrates leakage integrity shall be performed in lieu of system hydrostatic test.

Licensee's Code Relief Re uest:

The licensee requested relief from performing the Code-required pneumatic test on the following main steam discharge lines:

Line ¹ 10MS(18)-2-1 10MS(18)-2-2 10MS(18)-2-3 10MS(18)-2-4 10HS(18)-2-10 10MS(18)-2-11 10MS(18)-2-12 10MS(18)-2-13 10MS (18) 14 10MS (18) 9 IOMS (18) 8 10HS (18) 7 10HS(18) 6 10HS(18)-2-5 10HS(18)-2-18 10MS (18) 17 10HS(18)-2-16 10HS (18) 15 IS I Di a ram ¹ HS-301-1, -2, -3 HS-302-1, -2, -3 HS-303-1, -2, -3 HS-304-1, -2, -3 HS-305-1,-2,-3 HS-306-1,-2,-3 HS-307-1,-2,-3 MS-308-1,-2,-3 HS-309-1,-2,-3 HS-310-1,-2,-3 HS-311-1,-2,-3 MS-312-1,-2,-3 HS-313-1,-2,-3 HS-314-1,-2,-3 HS-315-1,-2,-3 HS-316-1,-2,-3 HS-317-1,-2, -3 HS-318-1,-2,-3 Licensee's Basis for Relief:

The license stated:

"The pressure test at less than two (2) percent of the operating pressure of the system does not add to the public safety.

The test adds

I t

I,

unnecessarily to the plants radiological exposure burden (approximately 1.6 person rems per outage).

This test has been eliminated in the 1992

Edition, 1992 Addenda to Section XI (see page 207 1992 Addenda to ASHE Section XI).

The pressure test required by the Code (6.6 psig) is significantly less than (less than 2X) the operating pressure of the discharge lines (388-465 psig).

The test pressure does not assure integrity of the piping and adds unnecessarily to the plants radiological burden.

Additionally, the Code required test has been deleted in the 1992

Edition, 1992 Addenda of ASHE Section XI."

Licensee's Pro osed Alternative Examination:

The licensee stated:

"No alternative to this test is proposed since this test has been eliminated from the later Section XI Code."

Evaluation The Code requires that for safety or relief valve piping that discharges into the containment pressure suppression

pool, a pneumatic test (at 90 percent of the pipe submergence head of water) that demonstrates the leakage integrity shall be performed in lieu of a system hydrostatic test.

The licensee proposed to delete the requirement to perform the pressure test and states that the requirement has been removed from the Code by the 1992 Addenda.

During a conference call between the staff and the licensee held Hay 11,

1995, the licensee reported that the subject lines were designed without test taps for pressurization of the lines.

In order to perform the required test, valves are required to be disassembled to allow a path for pressurization.

Considerable burden is associated with the disassembly and re-assembly of a valve in each of the subject discharge lines.

Therefore, the pressure test is impractical to perform at WNP-2.

In this case, 90 percent of submergence head is equivalent to a pressure of 6.6 psig.

This is much less than 388-465 psig (the operating pressure of the discharge lines) and does not significantly challenge the piping integrity.

~Conclusi o Based on the staff's preliminary evaluation, the pneumatic test on the main steam discharge lines is impractical to perform at WNP-2.

Therefore, the proposed relief is authorized on an interim basis pursuant to 10 CFR 50.55a(g)(6)(i).

2.

Relief Re uest No. 2ISI-06 Table IWB 2500-1 Examination Cate or 8-P Items 815.10 and 815.11 Control Rod Drive Flan e Boltin The control rod drive (CRD) flanges are subject to a system leakage test at the end of every refueling outage (item 815.10) and a hydrostatic test every inspection interval (item 815. 11). If leakage is observed at the bolted connection of these flanges, corrective action per IWA-5250(a)(2) requires all the bolting from that flange be removed and VT-3 visually examined for corrosion and evaluated per IWA-3100.

The purpose of this requirement is to determine if bolting degradation has occurred.

Code Re uirement:

Section XI, requires removal of bolting per IWA-5250(a)(2) to perform a visual examination.

Licensee's Code Relief Re uest:

The licensee requested a relief from the requirement to remove all the bolting to perform VT-3 visual examination.

Licensee's Basis for Relief:

The licensee stated:

"Relief is requested from the corrective action of IWA-5250(a)(2) based on the hardship to remove the cap screws from these flanges at the end of a refueling outage.

The pressure test is performed just prior to startup when the equipment required for cap screw removal has been removed from under the RPV.

To remove all the bolting from a leaking drive will require depressurization of the RPV and reassembly of the equipment necessary to remove the bolting.

The dose rates under the RPV in the area where bolting removal will occur are estimated to be between 200 mRem/hr at the knees and 600 mRem/hr at the head."

Licensee's Pro osed Alternative Examination:

The licensee stated:

"Relief is requested to use the following alternative examination for satisfying the requirements of IWA-5250(a)(2).

When control rod drives are exchanged, perform a VT-1 visual examination on the removed bolting.

This VT-1 examination will be in accordance with Table IWB-2500-1 Examination Category B-G-2, Item Number 87.80."

Evaluation The Code requires that all bolting at leaking mechanical connections be removed and VT-3 visually examined.

As an alternative, the licensee proposes to perform VT-1 visual examination in accordance with Table IWB-2500-1, Examination Category B-G-2, Item Number 87.80, when control rod drives are exchanged on the removed bolting.

Since the pressure test is performed just prior to startup, the equipment required for cap screw removal has been removed from under the RPV.

To remove all the bolting from a leaking joint will require depressurization of the RPV and reassembly of the equipment necessary to remove bolting.

This will result in additional radiation exposure to personnel under the RPV where the bolting will be removed.

The licensee's experience indicates that approximately 30-40 CRD flanges are disassembled for CRD exchange every 2 years.

During this activity all the CRD cap screws from the disassembled flanges are required to be VT-I visually examined in accordance with Examination Category B-G-2, item number B7.80.

The provisions of this examination are to determine if degradation of the bolting has occurred.

All the CRD flanges are disassembled and the cap screws examined within an approximate 10-year cycle.

The WNP-2 data indicates that during the first 10-year inservice inspection

interval, 187 sets of CRD screws received a VT-I visual examination after removal.

All new caps have receive a Preservice Inspection VT-I examination prior to installation.

Corrosion pitting has been observed on the cap screw's shank.

Metallurgical evaluation of the worst case from two outages was performed.

The analysis, concluded that the pitting was shallow and the ASME acceptance standards were not exceeded.

No cap screws that exhibited pitting corrosion were reused.

No failed bolting was found during the first 10-year inspection interval.

This demonstrates that the VT-I examinations required by Examination Category B-G-2, item number B7.80 provide an effective method to detect the early signs of bolting degradation.

Conclusion The licensee's alternative proposal to examine bolting when control rod drives are exchanged will provide an acceptable level of quality and safety.

Imposing the Code requirement to remove all the bolting to perform VT-3 visual examination will impose hardship on the licensee without a compensating additional level of quality and safety.

Therefore, the proposed alternative is authorized on an interim basis pursuant to 10 CFR 50.55a(a)(3)(ii).

3.

Re uest for Relief No. 2ISI Visual Examination of Bolted Connection er IWA-5250 a 2

This relief request applies to all bolted connections within the ASME Section XI pressure test boundary in non-borated systems except:

I) control rod drives and; 2) bolted connections that were assembled as part of a Section XI repair and replacement activity and have not been subject to inservice conditions.

Code Re uirement:

Section XI requires that if during pressure tests a bolted connection within the test boundary leaks it is subject to the corrective action of IWA-5250(a)(2).

This would require all the connection's bolting to be removed and visually examined to VT-3 requirements.

Licensee's Code Relief Re uest:

The licensee requested relief from the requirement to remove bolting per IWA-5250(a)(2) to perform a VT-3 visual examination.

'I I

censee's Basis for Re uestin Relief:

The licensee stated:

"Removing all the bolting from a leaking joint and performing a VT-3 visual examination on the bolting places a hardship on the plant.

Bolting degradation due to bolted connection leaks would not occur at bolting that was not exposed to the leaking fluid.

The Code requirement, if met, will require all the bolting at a leaking joint to be removed even if it is not in contact with the leaking fluid.

This will result in unnecessary work for, and radiation exposure to, plant personnel."

Licensee's Pro osed Alternative Examinatio The licensee stated:

"Relief is requested to use the corrective measures described in the following paragraphs.

For bolted connections that are shown to have metal-to-metal contact

("hard joints"), torque the bolted connection up to the maximum torque allowed for this joint while this joint is under pressure.

If the leak stops no further action will take place.

If the leak does not stop, the leakage will be evaluated for further corrective action.

For bolted connections other than hard joints, remove one bolt closest to the leak, perform a VT-3 examination for corrosion, and evaluate in accordance with TWA-3100."

Evaluation For bolted connections classified as hard joints, the licensee proposes to retorque the bolting to no greater value than that allowed for that specific joint.

This action will provi'de a more positive test that the bolting is not degraded than removing the bolting and performing a visual examination on it.

The retorquing will demonstrate that the bolting has not failed.

In addition to being a demonstration of the bolting integrity, the retorquing should stop the leakage condition, which can cause degradation of the bolting.

Where removal of the bolting is required for bolted joints other than hard joints, the removal of only one bolt will be performed.

This is supported by subparagraph IWA-5250(a)(2) of ASHE Section XI, 1992 Edition, 1993 Addenda.

By removing the bolt closest to the leak, the worst case condition will be examined.

Bolting that is not in contact with the leaking fluid will not be unnecessarily removed.

This will avoid unnecessary radiation exposure to plant personnel.

Conclus on The licensee's proposed alternative to torque the metal-to-metal joints up to the maximum allowed for the joint in order to stop the leak while the joint is under pressure is acceptable.

If the leak is not stopped, the licensee will evaluate the leakage for further action.

For bolted connection other than metal-to-metal joints, the licensee will remove one bolt closest to the leak

t

and perform VT-3 visual examination for corrosion and evaluation per IWA-3100.

Imposing the Code requirement to remove all the bolting to perform VT-3 visual examination will impose hardship on the licensee without a compensating increase in the level of quality and safety.

Therefor e, the proposed alternative is authorized, on an interim basis pursuant to 10 CFR 50.55a(a)(3)(ii).

4.

Re uest for Relief No. 2ISI-12 Defect Removal for ASHE Section III Code Class I 2

and 3 Pi in S stems and Com onents Code Re uirement:

ASHE Section XI, IWA-4340 requires that after the final grinding, the affected surfaces included surfaces of the cavities prepared for welding, shall be examined by magnetic particle (HT) or liquid penetrant (PT) method to ensure that the indication has been reduced to an acceptable level.

Licensee's Code Relief Re uest:

The licensee requested relief from performing HT or PT examination when defect elimination removes the full thickness of the weld where the back side of the weld joint is not accessible for removal of the examination material.

Licensee's Basis for Re uestin Relief:

The licensee stated:

"The basis for the relief is that when the full thickness of the joint is removed the defect is removed and the back side is not accessible, the NDE material cannot be properly applied or removed and a meaningful examinatio'n cannot be performed.

In addition, ASHE requirements have been clarified in the 1983 Edition of ASHE Section III and 1992 Edition of ASME Section XI."

Licensee's Pro osed Alternative Examination:

The licensee stated:

"The unacceptable indications will be removed by mechanical means or by the thermal gouging method as specified by ASHE Section III, Code Case N-275, "Repair of Welds".

The area prepared for repair will be examined by magnetic particle (MT) or liquid penetrant (PT) method in accordance with ASHE Section III, NX-5110 and the acceptable standards of ASHE Section III, NX-5300 as specified by ASME Section III, Code Case N-275.

The NDE examination is not required where the full thickness of the weld is removed and where the back side of the weld joint assembly is not accessible for removal of the NDE examination material as specified by

'SHE Section III, Code Case N-275.

The completed weld repair will be NDE examined in accordance with ASHE Section III, NX-4453.4 as specified by ASHE Section III, Code Case N-275.

Gouging through the wall in order to qualify for use of the ASME Section III, Code Case N-275 will not be used."

~Evaluatko The surface examination using magnetic particle (MT) or liquid penetrant (PT) methods of a through wall excavation, without ID access, resulting in NDE material such as magnetic powder or liquid penetrant dye or developer becoming

entrained in a plant piping system and creates a difficulty in'btaining a

meaningful NDE examination.

The ASHE Section III related piping systems and components at WNP-2 were constructed (material, designed, fabricated, installed, examined and tested) in accordance with ASHE Section III requirements.

The ASHE Section III requirements which were implemented during construction are also implemented during defect removal for ASHE Section XI repairs in conjunction with the requirements of ASHE Section III, Code Case N-275, "Repair. of Welds."

The licensee also committed that gouging through the wall in order to qualify for use of the ASHE Section III, Code Case N-275 will not be used.

Further, ASHE Section III and ASME Section XI, IWA-4331(a), page 34 of 1992 Edition with 1993 Addenda clarifies that magnetic particle (HT) or liquid penetrant (PT) examination is not required when defect elimination removes the full thickness of the weld wher e the back side of the weld joint is not accessible for removal of the examination material.

Conclusion The licensee proposes to eliminate the Code-required surface examination of weld repairs when the full thickness of the weld is removed and the back side of the weld joint is not accessible for removal of the examination material.

Performing HT or PT examination of the weld cavity when the full thickness of the weld is removed will entrain magnetic powder or PT in the piping system and will create difficulties to remove the material from the system, resulting in hardship without a compensating increase in the level of quality and safety.

Therefore, the proposed alternative to perform NDE examinations of completed weld repairs in accordance with ASME Section III is authorized on an interim basis pursuant to 10 CFR 50.55a(a)(3)(ii).

5.

Re vest for Relief No. 2ISI-14:

Bolted Mechanical Joints in ASHE Section III Code Class I 2

and 3 Pi in S stems and Com onents when Disassembled and Reassembled durin the Course of ASME Section XI Re air and Re lacement Activities Code Re uirement:

ASME Section XI, IWA-5250(a)(2) requires that if leakage is observed during VT-2 visual examination during the system pressure test at bolted mechanical joints, (I) remove all the bolting material associated with that joint, (2) perform VT-3 visual examination for localized general corrosion on the removed bolting material associated with that joint, (3) if the localized general corrosion reduces the bolting material cross sectional area by more than 5 percent, replace the unacceptable (corroded) bolting material.

Licensee's Code Relief Re uest:

The licensee requested relief from removal of bolting and performing VT-3 visual examination on bolting material for bolted mechanical joints in ASHE Section III, Code Class I, 2, and 3 piping systems and components disassembled and reassembled during the course of ASHE Section XI repair and replacement activities as required by ASHE Section XI, IWA-5250(8)(2).

1 1

icensee's Basis fo Re uestin Relic The licensee stated:

"Relief is requested from ASHE Section XI, IWA-5250(a)(2), removal and VT-3 visual examination of bolting material for bolted mechanical joints when leakage is observed during VT-2 visual examination during the system pressure test following ASHE Section XI repair and replacement activities.

The alternatives addressed below will provide an equivalent determination of whether the bolting material is degraded.

The alternatives provide acceptable detection of bolting corrosion in a Boiling Water Reactor (BWR) service with process systems not using borated water."

Licensee's Pro osed Alternative Examination:

The licensee stated:

"The following alternatives will be implemented to comply with the intent of ASHE Section XI, IWA-5250(a)(2) requirements.

These alternative requirements will be implemented when bolting material is replaced for bolted mechanical joints in ASHE Section III, Code Class I, 2,

and 3 piping systems and components during the course of ASHE Section XI repair and replacement activities and are not applicable to bolted mechanical joints disassembled and reassembled during, or as a result of, associated maintenance activities.

Bolted mechanical joints in air or gaseous systems will have a VT-2 visual examination performed of the bolting material as requi red by ASHE Section XI.

Any leakage observed from the bolted mechanical joint during VT-2 visual examination will be evaluated for acceptability or corrective action.

Bolted mechanical joints in other than air or gaseous systems where all new replacement bolting material is used will have a VT-2 visual examination performed on the bolted mechanical joint during system pressure test.

If leakage is observed from the bolted mechanical joint during the VT-2 visual examination it will be evaluated for acceptability or corrective action.

Bolted mechanical joints in other than air or gaseous systems where existing bolting material has been removed and is being reused will have a VT-3 visual examination performed on the bolting material prior to installation.

If leakage is observed from the bolted mechanical joint during the VT-2 visual examination during system pressure test it will be evaluated for acceptability or corrective action.

Existing bolting material reused without a VT-3 visual examination would include the bolting not required to be removed as part of the repair or replacement activity.

This bolting would be included in the ASHE Section XI system pressure test boundary.

Bolting material for mechanical joints for Control Rod Drives (CRD) will have a VT-I visual examination preformed on all the reused existing and/or new replacement bolting material prior to installation.

If leakage is observed from the bolted mechanical joint during the VT-2 visual examination during system pressure test it will be evaluated for acceptability or corrective action.

jvVatuati tt ASHE Section XI, IWA-5250(a)(2),

1989 Edition requires complete removal and inspection of all the bolting of a bolted mechanical joint for evaluation if leakage occurs at the joint during the system pressure test following ASHE Section XI repair and replacement activities.

This requirement applies even though the leakage could be very small and considered acceptable or known to stabilize or stop after a period of time.

This could require an unnecessary cooldown or shutdown of the plant, including extra unnecessary radiation exposure of personnel, and a delay in plant startup following an outage.

The purpose of ASHE Section XI, IWA-5250(a)(2) is to determine if inservice leakage has degraded the bolting material.

By installing new replacement bolting material or performing a VT-3 examination on the existing bolting material prior to reinstalling, the integrity of the bolting material is assured prior to performing the pressure test for repair and replacement activities.

WNP-2 is a

BWR that does not utilize a process system with a borated water chemistry, except the standby liquid control system, like a pressurized water reactor (PWR).

The corrosiveness of leaking borated water in a PWR is known but is not applicable to WNP-2.

The alternatives described provide assurance that corrosive conditions are evaluated.

VT-3 visual examination performed on the existing bolting material for mechanical joints prior to reassembly establishes a baseline that bolting corrosion is not present prior to installation.

Therefore, leakage observed during the VT-2 visual examination during the system pressure test, for the joint would be evaluated for acceptability to determine the corrosion effects on the bolting material or for corrective action.

The VT-1 visual examination performed on the reused existing and/or replacement (new) bolting material for the CRDs bolted mechanical joints prior to reassembly establishes a baseline that the bolting corrosion is not present prior to installation.

If leakage is observed during VT-2 visual examination during the system pressure test, the leakage from the bolted mechanical joint would be evaluated for acceptability to determine the corrosive effects on the bolting material or the corrective action.

~Cuastusi The licensee's alternative proposal to evaluate the integrity of bolted

'onnections disassembled and reassembled during the course of ASHE Code,Section XI repair and replacement activities provides, on an interim basis, an acceptable level of quality and safety contingent upon the licensee evaluating the leakage in accordance with IWB-3142.4 for joint integrity.

Therefore, the proposed alter native is authorized pursuant to 10 CFR 50.55a(a)(3)(i).

3.0 CONCLUSIO The staff evaluated the information submitted by WPPSS in support of its requests of relief.

Based on the information submitted, your request for relief 2ISI-05 is approved on an interim basis pursuant to 10 CFR 50.55a(g)(6)(i),

based on the impracticality of the applicable code requirement when applied to WNP-2, with due consideration of the burden upon the licensee, and will not endanger life or property or the common defense and security and is otherwise in the public interest.

Your requests for alternatives in relief requests 2ISI-06, 2ISI-07, and 2ISI-12 are approved on an interim basis pursuant to 10 CFR 50.55a(a)(3)(ii) because of the hardship to the utility without a compensating increase in the level of quality and safety.

Your request for alternatives in relief request 2ISI-14 is approved on an interim basis pursuant to 10 CFR 50.55a(a)(3)(i ) as providing an acceptable level of quality and safety.

These reliefs are granted on an interim basis until the NRC staff has completed its comprehensive review of WNP-2's inservice inspection program for the second ten-year interval.

Principal Contributor:

G. Georgiev Date:

dune 1, f995

0 r

k C

i i

l