ML20195B252

Submits Response to RAI Re LAR for Tube Repair Using Leak Limiting Alloy 800 Sleeves for Ccnpp,Units 1 & 2.Test Repts Encl

ML20195B252
Person / Time
Site:	Calvert Cliffs
Issue date:	05/25/1999
From:	Cruse C BALTIMORE GAS & ELECTRIC CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20195B258	List: ML20195B252 ML20195B275 ML20195B286
References
NUDOCS 9905280200
Download: ML20195B252 (6)

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CHC LES II. CCUSE Baltimore Gas and Electric Company Vice President Calven Cliffs Nuclear Power Plant Nuclear Energy 1650 Calvert Cliffs Parkway Lusby, Maryland 20657 410 495-4455 P

May 25,1999 U, S. Nuclear Regulatory Commission Washington, DC 20555 ATTENTION: Document Control Desk

SUBJECT:

Calvert Cliffs Nuclear Power Plant Unit Nos.1 & 2; Docket Nos. 50-317 & 50-318 Response to Request for Additional Information - License Amendment Request:

Tube Renair Using Leak Limiting Alloy 800 Sleeves

REFERENCE:

(a) Letter from Mr. C. II. Cruse (BGE) to NRC Document Control Desk, dated November 30,1998, License Amendment Request: Tube Repair Using Leak Limiting Alloy 800 Sleeves By letter dated November 30,1998 (Reference a), Baltimore Gas and Electric Company (BGE) submitted a license amendment request to the Nuclear Regulatory Commission (NRC) to allow the repair of defective steam generator tubes with leak-limiting Alloy 800 repair sleeves. This letter responds to the Commission's request for additional information made during a teleconference held on March 22,1999, between the NRC staff and BGE.

NRC REOUEST No.1 The Calvert Chfs TechnicalSpecification 5.5.9.d.9, Tube inspection, page 5.0-18, specifies that a tube is inspectedfrom the point of entry (hot leg side) completely around the U-bend to the top support of the cold leg. This requirement may need to be changed to include inspection of entire length of a tube in case a sleeve is installed in the region below the top support ofthe coldleg. '

RESPONSE

Technical Specification 5.5.9.d.9 specifies the minimum inspection requirement. However, BGE is committed to implementing both Nuclear Energy Institute (NEI) 97-06, Steam Generator Program  !

Guidelines," and the Electric Power Research Institute's "PWR [ Pressurized Water Reactor) Steam i Generator Examination Guidelines," which require inspection of the entire length of the tube.

Therefore, we believe there is no need for changing the Technical Specification requirement to ensure

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inspection of the entire length of the tube in the event Leak Limiting Alloy 800 Sleeves are installed f

in the cold leg side. It is also noteworthy to mention the ongoing NRC/ industry effort that will go eventually remove the kind of detailed inspection requirement specified in Technical Specification 5.5.9.d.9 out of the Technical Specifications.

9905280200 990525 PDR ADOCK 050003173 P PDR ,

f Document Control Desk May 25,1999 Page 2 NRC REQUEST No. 2 i The November 30,1998 letter stated that sleeve locations arefrom thefourth eggerate support doun to the top of the tubesheet. This restriction was not speciped in the Asea Brown Boveri, Inc.-Combustion i Engineering, Inc. [ABB-CE] report. Why is this restriction applied to Calvert Chfs Units 1 and 2 steam generators?

RESPONSE

Page 2-2, Paragraph 1 of the ABB CE report states that the eggerate support sleeve may be installed up to and including the fourth eggerate support. Therefore, the restriction is not unique to Calvert Cliffs' application.

NRC REQUEST No. 3 Describe how sleeve indications will be dispositioned in Calvert Chfs. ABB-CE recommends plugging on detection. Would the licensee follow the practice of plug on detection or some other practice, e.g., sizing technique? Where would the licensee document its practice on disposition of sleeve indications?.

RESPONSE

Baltimore Gas and Electric Company will plug, on detection, any Alloy 800 sleeve that exhibits credible indication without relying to sizing techniques. Plugging on detection will be documented in the Steam Generator Program Document. The inspection practices for Alloy 800 sleeves will be addressed in the Calvert Cliffs Steam Generator Eddy Current Guidelines.

NRC REQUEST No. 4

. On Page 2-1 (second to the last paragraph), 2 2 (secondparagraph), and 3-2 (item 5) of the ABB-CE

. report, it is stated that the corrosion test is ongoing and there are tests stillin process. What is the status ofthe corrosion test and clarify the tests that are still in process.

RESPONSE

The corrosion tests are completed and Report No. 98-FSW-021 has been issued and is included as Attachment (1) to this letter.

NRC REQUEST No. 5 On Page S-2 of the ABB-CE report, the use ofplus point probefor inspecting siceves is discussed. The staf noted that in a domestic nuclear plant, a routine sleeve (not Alloy 800 sleeve) inspection showed that a large indication having large voltage responses in the tube masked the voltage responses)hom smaller indications in the sleeve when both sleeve indication and tube indication occur on the same elevation of the tube. The problem was resolved by combining a highfrequency coil with the existing lowfrequency coil in the probe. What are the inspection procedures implemented to avoid the same problem?

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r-t Docum ntControlDesk May 25,1999 Page 3 RESPONSE '

ABB-CE has adopted a high frequency coil as part of the inspection technique in the Tungsten Inest Gas-welded sleeve program. This technique will be continued for the Alloy 800 Program.

NRC REQUEST No. 6 On Page 7-2 of the ABB-CE report: '(1) The mechanical tests used expansion transition sone (ETZ) 1 samples but there was no discussion of eggcrate support (ECS) samples being used in the mechanical b tests. It is not clear that the result.: of EIZ sample tests are applicable to ECS sleeves, because EIZ sleeves contain hard rolledjoint, whereas ECS sleeves do not. (2) The efect of the yield strength of the tube on contact stress andload carry cqpability was discussed. However, the efect of the sleeve yield strength was not discussed. Discuss the efect of the sleeve yield strength on the overall sleeve-tube assembly. (3) The location ofthefaw in the test specimen was in the middle of the sleeve and not at the }

transition zone of a hydraulic expansionjoint. It is not clear if theflaw location in the specimen is at a structurally weakpoint, or apoint where actualfaw would most likely to occur. Discuss the validity of Ihefawlocation.

RESPONSE

1. ' Leak rate tests were performed on both ETZ and ECS samples. The results of these tests are summarized in Tables 7-2 and 7-3 of the ABB-CE report. The mechanical tests were performed on full-length samples, and tl.e loading was applied to both the rolled joint and the hydraulically-expanded joint. Afterward, the tube was severed between the joints, and only the hydraulically-expanded joint was loaded. These test results then apply to both types of sleeve joints since the hydraulic expansions are identical for both.

--2. ' Report No. 98-TR-FSW-005 (Reference 7.5.9 of the ABB-CE Report) discusses the testing that was performed on low yield strength tubing. Report No. 98-TR-FSW-005, Revision 00, is included as Attachment (2) to this letter.

3. The " flaw" in these test specimens was a drilled hole in the parent tube between the joints. This hole was made in order to measure leak rates across the hydraulically-expanded joint during leak rate testing. The hole was not placed in the tube with the intent of simulating a flaw.

NRC REQUEST No. 7

\ Table 7-1 ofthe ABB-CE Report shows results ofmechanical testing. The stafneeds more details of the tests. (1) Provide a list of a matrix of each test. For each test, identify each sample, and provide corresponding numerical tests results. (2) For each sample, identify whether it is an EIZ sleeve sample or ECS sleeve sample. (3) Identify the location and size of the simulatedfaws in each sample. '(4) For each test results, indicate whether safety margins in Regulatory Guide 1.121 (Bases for Plugging Degraded PWR Steam Generator Tubes) were satisped.

RESPONSE

.1. The table bel;w summarizes the type and number of tests that were performed. As discussed in the test report, tests were performed on specimens that had the parent tube severed between the upper and lowerjoints in order to load the hydraulically-expanded joint. 'Ihere were also tests performed on the lower rolled joint, as discussed in the report. The actual test values are reported in Section 7 of the report.

Document Control Desk May 25,1999 Page 4

2. The samples tested were hard-rolled joint samples. Derefore, they cannot be identified as ETZ or ECS sleeve samples.

3. See response to Request No. 6, Item 3 above.

4. The test program was designed to meet the requirements of Regulatory Guide 1.121. Table 3-1 in the ABB-CE report summarizes the acceptance criteria and refers to the applicable section of the report.

. TEST TYPE - NUMBER OF SPECIMENS Room Temperature (RT)

Cyclic Loading (Wear Test) 1 (132,000 cycles)

Cyclic Loading (Axial Load) 1 (136,000 cycles)

Operating Temperature (OT)

Axial Loading 6 l Sleeve Burst 1 l Sleeve Collapse 2 Cyclic Loading 2 Thermal & Load Cycling 2 Sleeve Collapse 2 Various Leak (RT to OT) 40 Low Yield Strength Tubes Leak 6 Hermal & Load Cycling 2 l

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i Document Control Desk i May 25,1999 Page5 The above responses do not change the No Significant liazards Determination previously provided.

Should you have questions regarding this matter, we will be pleased to discuss them with you.

Very truly yours, I

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STATE OF MARYLAND  :

TO NT:

l COUNTY OF CALVERT  :

I, Charles II. Cruse, being duly sworn, state that I am Vice President, Nuclear Energy Division,

. Baltimore Gas and Electric Company (BGE), and that I am duly authorized to execute and file this response on behalf of BGE. To the best of my knowledge and belief, the statements contained in this document are true and correct. To the extent that these statements are not based on my personal knowledge, they are based upon information provided by other BGE employees and/or consultants. Such information has been reviewed in accordance with company pra

• e and I believ o be reliable.

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Supribed and sworn before me, p Notary Public in and for the State of Maryland and County of

/ L//nai , this M@ day of bb- ,1999.

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l MTNESS my 11and and Notarial Seal: M I Notary Public " l My Commission Expires: A/L/Au /> Add /s

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CllC/GT/ dim Attachments: (1) ABB-CE Report No. 98-FSW-021 (2) ABB-CE Report No. 98-FSW-005 cc: (With Attachments)

A. W. Dromerick l (Without Attachments)

R. S. Fleishman, Esquire Resident inspector,NRC l J. E. Silberg, Esquire R. I. McLean, DNR l . S. S. Bajwa, NRC J.11. Walter, PSC l 11. J. Miller, NRC E. P. Kurdziel, ABB-CE l

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ATTACHMENT (2) l ABB-CE Report No. 98-FSW-005 l

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Baltimore Gas & Electric Company Docket Nos. 50-317 and 50-318 May 25,1999