ML20072R673

Part 21 Rept Re Increased Air Leakage in Pathway Bellows Corp Bellows Assembly.Assembly Replaced by Parker-Metal Bellows Corp

ML20072R673
Person / Time
Site:	Quad Cities
Issue date:	03/27/1991
From:	Kovach T COMMONWEALTH EDISON CO.
To:	Davis A NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
REF-PT21-91 NUDOCS 9104030046
Download: ML20072R673 (6)

Text

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/ N C:mm:nwealth Edison "(.

• .+ [ 1400 Opus Place

( '-_ /^J Downers Grove, Ulinois 60515 N J March 27, 1991 Mr, A. Bert Davis Regional Administrator U.S. Nuclear Regulatory Commission 799 Roosevelt Road Glen Ellyn, IL 60137

Subject:

Quad Cities Nuclear Power Station Unit I and 2 10 CFR Part 21 Notification NRC_DocheLNon _50:254. and 50-265. _ 2 Mr. Davis:

During the performance of the Quad Cities Station Unit 1 containment 16tegrated leak rate test pursuant to 10 CFR 50 Appendix J, increased air leakage was identified from containment penetration X-25. An investigation to identify the cause of the leakage was conducted. During that investigation, it was found that the two-ply bellows assembly had been successfully tested pursuant to the 10 CFR 50 Appendix 3 Type B test requirements. As a result of the inconsistent test data, Commonwealth Edison conducted various tests of the two-ply bellows and has concluded that a valid Type B test cannot be performed on the bellows assembly.

On March 22, 1991, Commonwealth Edison notified B. Burgess, Branch Chief via telephone of the evaluation of the two-ply bellows assembly, which was performed pursuant to 10 CFR Part 21. While the evaluation conclusions did not strictly meet the criteria which is contained in 10 CFR Part 21, Commonwealth Edison considered the evaluation conclusions to be significant and thereby warranted formal notification to the Commission. Enclosed are three (3) copies of the report which contains the information required by 10 CFR Part 21.21(b)(2).

If there are any questions regarding this notification, please direct them to R. Stols at (708) 515-7283 or H. Massin at (708) 515-7450.

, Very truly yours, b (  !' A /

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• O T.J. Kovach Nuclear Licensing Manager I$

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$cc Director, Office of Nuclear Reat B.L. Burgess, Section Chief, Region III Ng% g\ 1

& T.L. Taylor, Senior Resident Inspector, Region III L.H. 01shan, Project Manager, NRR

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10 CFR 21 NOTIFICATION Type B Testability of Primary Containment Penetration Bellows Applicability This Notification is submitted in accordance with the requirements of 10 CFR 21, Section 21.1.(b), 21.3.a.(3), and 21.3.d.(4).

Identification _of_fAtilltrand Component This Notification concerns the local leak rate testing of primary containment mechanical penetrations fitted with two-ply expansion bellows.

Recent integrated and local leak rate testing, which was conducted on an expansion bellows assembly at the Quad Cities Nuclear Power Station, indicates that these bellow assemblies are not testable per the requirements of 10 CFR 50 Appendix J (Type B testing only). The evaluation of information regarding the bellows testing discrepancy was completed oa March 22, 1991.

I d e n t i f i Cat 10D_of_ComponeAt_flitWfAC t uffr The subject bellows assemblies were manufactured and supplied by:

Pathway Bellows Corporation 115 Franklin Road Oak Ridge, TN 37330 (615) 483-7444 These assemblies are original plant equipment which were manufactured and installed in the late 1960's and early 1970's. It is believed that t.he bellows design has remained essentially unchanged; therefore, bellows which were manufactured in subsequent years would also be subject to the same concern regarding the ability to perform a valid Type B test.

Natur1_Qf_Deftti The bellows assemblies which were supplied by Pathway Bellows Corporation were in full compliance with the procurement specification. Commonwealth Edison has determined that any potential leakage of the bellows during the performance of a 10 CFR 50 Appendix J, Type B test cannot be properly quantified due to the construction of the bellows. This testing deficiency is the subject of this Notification.

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Tha flexible metallic bellows are constructed with two plies of austenitic, type 300 series stainless steel which are formed together into a cylindrical corrugated element. This design configuration is typical of bellows penetrations that are installed at major piping penetrations and for the drywell ventilation and purge lines (in-line ballows assemblies). The forming process can bring the plies into contact, thus limiting flow of the local leak rate test medium (inert gas or air) between the inner and outer plies. Based upon our evaluation of the local leak rate test (LLRT) and integrated leak rate test (ILRT) results of this flexible metallic bellows assembly, the LLRT is capable of detecting leakage but cannot be relied upon to accurately quantify the actual leakage rate.

A Type B test was performed on the 18" Orywell Ventilation Penetration.

X-25. The measured leakage rate was 6 scfh. Approximately two days after the LLRT, the primary containment ILRT was performed. While the containment was at pressure, application of a soap solution to the surface of the bellows revealed one large crack and over a hundre; small indications. Following the ILRT, a Type B test was again performed and the results duplicated the initial LLRT leakage rate. A soap solution was applied to the bellows during this LLRT and Identified only a few small leaks.

A " local" ILRT was subsequently performed in an effort to quantify actual leakage from the bellows. A steel plate was welded to the ventilation line inlet inside of the drywell. The bellows were pressurized from ite inside through a threaded hole in the plate and a leakage rate test was performed on the entire ventilation penetration. The soap solution revealed a large leak along with many small leak 3 which were similar to the ILRT results. A leakage rate 137 scfh was measured.

With the validity of the Type B tests now in question, Station personnel examined the sensitivity of the LLRT procedure to detect and quantify new cracks. A 0.25" hole wcs drilled through the two bellows from the outside diameter to the inside diameter. A Type B test was performed and resulted in a small increase in leakage to 7 scfh. A second 0.25" hole was drilled through each of the bellows. The subsequent Type B test resulted in a leakage of 8 scfh. It was concluded that air flow between the bellows through the area which contained the large crack was vnry restricted. The Type B test, therefore, can only detect additional through-wall leakage and cannot quantify the extent of the leakage.

The bellows were subsequently sent offsite to Argonne National Laboratory (AHL) to conduct destructive testing of the bellows. Physical examination of the bellows cross-saction revealed that a tight metal-to-metal contact occurs in the convolutions, at the inflection point between the inner and outer apexes. The shape of the convolutions as-formed is such that the inner and outer convolutions are tightly interlocked at the inflection point. A gap size of 0.002-0.010 was measured at the apexes, which is the maximum gap location.

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Safety _SL9attt iance The perfermance of an ILRT properly challenges the bellows elements. i Operability c/ the Primary Containment structure was, therefore, demonstrated through ine iLRT performed at the end of the refueling outage. Bellows with high leak'ge rates which are undetected by the local leak test will result in a acti.eable increase in ILRT results. Based upon an ILRT value adjusted for the X-25 leakage, it was determined that all other plant bellows collectively have a leakage rate sufficiently low such that the overall ILRT performance is not impacted.

COIR.eitirelttions To ensure the acceptable performance of the. penetration, the bellows assembly was replaced during the outage. The new bellows assembly was supplied by Parker-Hetal Bellows Corporation. Six other penetration bellows with known positive leakage rates as established by recent LLRT's, were examined. Visual and penetrant examinations of these bellows showed no indication of flaws. Commonwealth Edison is currently investigating several leak rate testing methods that would provide accurate LLRT results for bellows assembly penetrations.

Hellow LQIAt1001-Bellows assemblies of this design are installed at the Quad Cities Nuclear Power Station and the Dresden Nuclear Power Station. Attachments A and B list the locations of all bellows assembly penetrations for Quad Cities and Dresden, respectively.

Contas11 Questions pertaining to this Notification should be addressed to:

Mr. H.L. Massin BWR Systems Design Superintendent Commonwealth Edison Company 1400 Opus Place, Suite 400 Downers Grove,_IL 60515 (708) 515-7460 Mr. D. Fisher BHR Systems Design System Engineer Commonwealth Edison Company 1400 Opus Place, Suite 400 Downers Grove, IL 60515

-(708) 515-7428 ZHLD808/21

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10 CFR 21 Nottfl'.ation Attachment A Quad Cities Station Bellows Locations Quad Cities Nuclear Power Station Penetration Unit 1 Unit 2 X-7A A Main Steam Line X X X-78 8 Main Steam Line X X X-7C C Main Steam Line X X X-7D D Main Steam Line X X X-8 Main Steam Line Drain X X X-9A A Feedwater Line X X X-96 B Feedwater Line X X X-10 RCIC Steam Supply X X X-11 HPCI Steam Supply X X X-12 SDC Supply X X X-13A A LPCI Injection X X X-13B b LPCI Injection X X X-14 PHCU Suction X X X-16A A Core Spray (*) X X-16B B Core Spray (*) (*)

X-17 Head Spray X X X-23 RBCCH Supply X X X-24 RBCCH Return X X l X-25 Drywell Vent X X X-26 Drywell Supply X X X-36 CR0 Return X X X-47 Standby Liquid X X l

X - Installed on this Unit.

! (*) - Bellows replaced with clamshell design l

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10 CFR 21 Notification '

Attachment D Dresden Station Bellows Locations Dresden Nuclear Power Station Penetration Unit 1 Unit 2 X_195A A Steam Line X X X-1058 8 Mu Steam Line X X X-105C C Nain Steam Line X X X-105D D Mcin Steam Line X X X-106 Main Steam Line Drain X X X-107A A Feedwater Line X X X_107B B Feedvater Line X X X_108A Iso. Cond. Steam X X X_109A Iso. Cond. Return (N/A) X X-1098 Iso. Cond. Return X (N/A)

X-Illa A Shutdown Cooling X X X_111B B Shutdown Cooling X X X-113 RHCU X

X '16A A LPCI Injection X X X-)l6B B LPCI Injection X X X-123 RBCCH Supply X X X-124 RBCCH Return X X X-125 Drywell Vent X X X-126- Drywell Supply X X X-115A HPCI Steam Supply X (N/A)

X-12B HPCI-Steam Supply (N/A) X X-130 Standby Liquid Inlet X (N/A)

X-138 Standby Liquid Inlet (N/A) X X-144 CRD Return X (N/A)

X-147 Head Spray X X X-149A A Core Spray X X X-1498 B Core Spray X X X - Installed on this Unit.

(N/A) - Not applicable to this Unit.

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