ML103280197

OL - for Your Review - Watts Bar Unit 2 - Draft RAI for Section 3.11 EQ

ML103280197
Person / Time
Site:	Watts Bar
Issue date:	11/19/2010
From:	Office of Nuclear Reactor Regulation
To:	Division of Operating Reactor Licensing
References
Download: ML103280197 (5)

Text

WBN2Public Resource From: Lamb, John Sent: Friday, November 19, 2010 2:09 PM To: 'garent@tva.gov'; Crouch, William D Cc: Campbell, Stephen; Lyon, Fred; Raghavan, Rags; Milano, Patrick; Poole, Justin; Wiebe, Joel; WBN2HearingFile Resource

Subject:

For Your Review - Watts Bar Unit 2 - Draft RAI for Section 3.11 EQ Attachments: RAI SSER 22 Section 3 11.docx Importance: High Gordon & Bill, Attached, for your review, is a draft RAI regarding Section 3.11 EQ. Please review to ensure that the questions are understandable, the regulatory basis is clear, there is no proprietary information contained in the RAI, and to determine if the information was previously docketed. Please also let me know how much time TVA needs to respond to the RAI.

Thanks.

John 1

Hearing Identifier: Watts_Bar_2_Operating_LA_Public Email Number: 193 Mail Envelope Properties (BE1CC4A72435624D84F8699734202B3E2556F23CDF)

Subject:

For Your Review - Watts Bar Unit 2 - Draft RAI for Section 3.11 EQ Sent Date: 11/19/2010 2:09:15 PM Received Date: 11/19/2010 2:09:18 PM From: Lamb, John Created By: John.Lamb@nrc.gov Recipients:

"Campbell, Stephen" <Stephen.Campbell@nrc.gov>

Tracking Status: None "Lyon, Fred" <Fred.Lyon@nrc.gov>

Tracking Status: None "Raghavan, Rags" <Rags.Raghavan@nrc.gov>

Tracking Status: None "Milano, Patrick" <Patrick.Milano@nrc.gov>

Tracking Status: None "Poole, Justin" <Justin.Poole@nrc.gov>

Tracking Status: None "Wiebe, Joel" <Joel.Wiebe@nrc.gov>

Tracking Status: None "WBN2HearingFile Resource" <WBN2HearingFile.Resource@nrc.gov>

Tracking Status: None

"'garent@tva.gov'" <garent@tva.gov>

Tracking Status: None "Crouch, William D" <wdcrouch@tva.gov>

Tracking Status: None Post Office: HQCLSTR01.nrc.gov Files Size Date & Time MESSAGE 408 11/19/2010 2:09:18 PM RAI SSER 22 Section 3 11.docx 32700 Options Priority: High Return Notification: No Reply Requested: No Sensitivity: Normal Expiration Date:

Recipients Received:

Environmental Qualification of Mechanical and Electrical Equipment The NRC staff reviewed FSAR Amendments 95 and 100 (ADAMS Accession Nos.

ML093370275 and ML102530216, respectively), and supplemental information provided by TVA in letters dated August 6, August 30, and September 1, 2010 (ADAMS Accession Nos.

ML102210440, ML102510580, and ML102500170, respectively), and Section 3.11 of the original SER supplement prepared for the environmental qualification (EQ) of mechanical and electrical equipment (SSER 15).

Qualification Methods

1. In its FSAR amendments and supplemental letters, TVA stated that qualification tests and analyses for safety-related electrical equipment were conducted in accordance with the requirements of 10 CFR 50.49 and the guidelines of NUREG-0588, Revision 1. In NUREG-0588, Revision 1, the NRC staff presents detailed procedures for qualifying safety-related electrical equipment in a harsh environment. The NUREG-0588 criteria apply to equipment that is important to safety as defined in 10 CFR 50.49.

The staff concluded that the qualification methods used by TVA are consistent with NRC regulations and are, therefore, acceptable. However, based on the extensive layup period of equipment within WBN Unit 2, the NRC staff must review, prior to fuel load, the assumptions used by TVA to re-establish a baseline for the qualified life of equipment.

The purpose of the staffs review is to ensure that TVA has addressed the effects of environmental conditions on equipment during the layup period.

Please provide the assumptions used by TVA to re-establish a baseline for the qualified life of equipment based on the extensive layup period of equipment within WBN Unit 2.

Electrical Equipment in a Harsh Environment

2. Please provide TVAs EQ program procedures for WBN Unit 2.

3. The NRC staff requested TVA confirm that equipment being replaced or refurbished will be qualified as Category I, as required by 10 CFR 50.49. In its response dated September 1, 2010, TVA stated that replaced equipment is being procured qualified to the NUREG-0588, Category I requirements. TVA also stated, however, that a small population of components is being refurbished. The NRC staff reviewed these components as noted below.

3a. All 6.9 kV motors will be refurbished TVA considers the refurbishment activities to be routine maintenance that do not impact the qualification of the motors. The staff considers that routine maintenance activities should result in increasing the EQ of the motors to Category I status in accordance with 10 CFR 50.49. Please justify refurbishment of all 6.9 kV motors impact on EQ.

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3b. Terminal Blocks TVA stated that it noted during a field walkdown that the terminal blocks installed in the EQ application for WBN Unit 2 are GE-make CR151B. According to TVA, these terminal blocks are qualified to NUREG-0588, Category I. TVA further noted that design modifications have been issued to inspect and replace the EQ terminal blocks that are found damaged or degraded with equivalent CR151B blocks.

Please clarify the use of the term equivalent (e.g., identical, similar) regarding the replacement terminal blocks. If the blocks are similar, please complete a similarity analysis and provide it to the NRC staff for review.

3c. Main Steam Isolation Valves (MSIVs)

TVA stated that the original WBN Unit 2 MSIVs are qualified to NUREG-0588, Category II. The MSIVs are being refurbished by replacing the missing subcomponents, including the solenoid valves, terminal blocks and manufacturing wiring, with components of the same make, model, and type as supplied on the original purchase order. With the exception of the solenoid valves, the subcomponents will be qualified to NUREG-0588, Category I requirements. According to TVA, the solenoid valves cannot be upgraded because equivalent subcomponents qualified to NUREG-0588, Category I requirements are not available.

Please justify not upgrading the MSIV solenoid valves to Category I in light of 10 CFR 50.49(l).

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4. Mild Environment The NRC staff requested that TVA clarify that, for a mild environment, the threshold for electronic components such as semiconductors or electronic components containing organic material is a total integrated dose of less than 1x103 Rads, and that a threshold for a mild radiation environment for other equipment is less than 1x104 Rads. In its response dated August 30, 2010, TVA stated that the upper threshold for the EQ Mild Environment is 1x104 Rads for all components, which is consistent with WBN Unit 1.

Since certain components may have a lower threshold for impacts from radiation exposure, TVA stated that it requires the following at WBN:

• Per design standards, any device, whether in a mild, essentially mild, or harsh environment, is required to be purchased to the environmental conditions where it is to be located. That includes the usual radiation, temperature, humidity, etc.

guidelines. An environmental conditions data sheet with the stated environmental parameters is sent to the manufacturer along with the purchase request and [TVA asks] the vendor to meet those conditions.

• For MOS [metal oxide semiconductors], CMOS or like circuitry, the same holds true. But, the design standard for qualification of electrical equipment in a harsh environment specifically requires that any of this type circuitry be evaluated on a case-by-case basis for any gamma dose exceeding 1x103 Rads.

Please provide supporting documentation to justify TVAs establishment of a mild environment threshold for total integrated dose of less than 1x103 Rads for electronic components such as semiconductors or electronic components containing organic material.

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