ML070580385
| ML070580385 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 02/28/2007 |
| From: | Moroney B NRC/NRR/ADRO/DORL/LPLII-2 |
| To: | Singer K Tennessee Valley Authority |
| B. Moroney, LPL2-2 | |
| References | |
| TAC MD0145 | |
| Download: ML070580385 (7) | |
Text
February 28, 2007 Mr. Karl W. Singer Chief Nuclear Officer and Executive Vice President Tennessee Valley Authority 6A Lookout Place 1101 Market Street Chattanooga, TN 37402-2801
SUBJECT:
SEQUOYAH NUCLEAR PLANT, UNIT 2 REQUEST FOR ADDITIONAL INFORMATION REGARDING THE STEAM GENERATOR TUBE INTEGRITY TECHNICAL SPECIFICATION AMENDMENT (TAC NO. MD0145)
Dear Mr. Singer:
By letter dated February 15, 2006 (ML060600405 [Agencywide Document Access and Management System Accession Number]), Tennessee Valley Authority (TVA, the licensee),
requested a license amendment for Sequoyah Nuclear Plant, Unit 2, concerning steam generator tube integrity. The licensees proposed revisions are based on the Nuclear Regulatory Commission (NRC)-approved Revision 4 to Technical Specification Task Force (TSTF) Standard Technical Specification Change Traveler 449 (TSTF-449), Steam Generator Tube Integrity (ML051090200). The amendment would also remove an operating license condition associated with use of the voltage-based alternate repair criteria. In a letter dated November 30, 2006 (ML063390665), the licensee responded to a request for additional information (RAI) from the NRC staff dated November 7, 2006 (ML062840716). Based on review of this response to its RAI, the staff needs additional information.
In order for the staff to complete its review, we request that TVA provide responses to the enclosed RAI. Based on discussions with your staff, we understand that you plan to respond to the enclosed RAI by April 2, 2007. If you have any questions about this material, please contact me at (301) 415-3974.
Sincerely,
/RA/
Brendan T. Moroney, Project Manager Plant Licensing Branch II-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No: 50-328
Enclosure:
As stated cc w/enclosure: See next page
ML070580385 NRR-088 OFFICE LPL2-2/PM LPL2-2/LA CSGB/BC LPL2-2/BC(A)
NAME BMoroney RSola AHiser as signed on BRMozafari DATE 02/28/07 02/28/07 01/11/07 02/28/07
Enclosure REQUEST FOR ADDITIONAL INFORMATION STEAM GENERATOR TUBE INTEGRITY TECHNICAL SPECIFICATION AMENDMENT TENNESSEE VALLEY AUTHORITY.
SEQUOYAH NUCLEAR PLANT, UNIT 2 DOCKET NO. 50-328 By letter dated February 15, 2006 (ML060600405), Tennessee Valley Authority (the licensee) requested a license amendment for Sequoyah Nuclear Plant, Unit 2 to replace the existing steam generator (SG) tube surveillance program with the program being proposed by the Technical Specification Task Force (TSTF) in TSTF-449, Revision 4. The proposed change revises the Technical Specifications (TS) definition of Leakage, as well as the TS and Associated Bases for Specifications 3.4.5, Steam Generator (SG) Tube Integrity, and 3.4.6.2, Operational Leakage. The change also adds Specifications 6.8.4.k, Steam Generator (SG)
Program, and 6.9.1.16, Steam Generator Tube Inspection Report.
In a letter dated November 30, 2006 (ML063390665), the licensee responded to a request for additional information (RAI) from the NRC staff dated November 7, 2006 (ML062840716).
Based on review of this response to its RAI, the staff needs the additional information requested below:
1.
On page E2-22 of your November 30, 2006,response, the proposed TS 6.8.4.k.d.,
Provisions for SG Tube Inspections, contains a statement about, meeting the requirements of d.1, d.2, d.3, and d.4 below... Since there is now a proposed fifth paragraph under this section (i.e., W* Inspection), the statement above should refer to meeting the requirements of d.1, d.2, d.3, d.4, and d.5. Please discuss your plans to modify this statement.
2.
In Question #4 of the November 7, 2006, RAI, the staff requested that your proposed TS define the abbreviations ODSCC (outside diameter stress corrosion cracking) and TSP (tube support plate). Proposed TS 6.8.4.k.b.1, page E2-19, spells out the term outside diameter stress corrosion cracking but does not follow it with the abbreviation ODSCC.
Therefore, the abbreviation ODSCC is still not clearly defined when it is introduced on page E2-20. Also on page E2-20, the abbreviation GL is not defined when it is introduced (GL 95-05 Voltage-Based ARC (Tube Support Plate [TSP]). Please discuss your plans to ensure abbreviations are defined (e.g., words spelled out, followed by abbreviation in parentheses).
3.
In Question #5 of the November 7, 2006, RAI, the staff requested clarification on the descriptions of leakage limits in the proposed TS and TS Bases because they were inconsistent with the TSTF-449 language and appeared incomplete in the way they addressed non-faulted steam generators and alternate repair criteria (ARC).
The proposed TS Bases, on page E3-6 under Applicable Safety Analyses, now state, In these analyses, the steam discharge to the atmosphere is based on a primary to secondary leakage of 0.1 gallons per minute (gpm) for the non-faulted SGs and 3.7 gpm for the faulted SG with no more than 1.0 gpm of the 3.7 gpm coming from non-alternate repair criteria. This statement still leaves out the phrase from TSTF-449, or is assumed to increase to [1.0 gpm or the plant-specific limits] as a result of accident-induced conditions. Please discuss your plans to modify your proposal to reflect that leakage may increase as a result of accident-induced conditions.
In addition, this statement implies that the exceptions to the 1.0 gpm limit are simply based on whether the leakage is addressed by an alternate repair criteria. Although this may currently be the case (i.e., the only exceptions to the 1 gpm limit are for ARC sources), it is possible that the staff could approve exceptions to the 1.0 gpm limit for sources of leakage other than those addressed by ARC and the staff may not permit the leakage from all ARC sources to be excluded from the 1.0 gpm limit. As a result, please discuss your plans to modify this statement to reflect this consideration.
This same paragraph indicates that "This limit [presumably the 3.7 gpm limit] is approved for use for alternate repair criteria (ARC) and W* leakage calculations." Please discuss your plans to modify this statement per the discussion above regarding exclusions to the 1.0 gpm limit. In addition, it is not clear why the W* leakage calculations are called out separately from other alternate repair criteria. As a result, discuss your plans to clarify this part of the sentence.
This same paragraph indicates that for non-ARC applications, the accident-induced leakage in the faulted steam generator is limited to 1.0 gpm which is bounded by the maximum leakage established by the plant safety analysis. Please discuss your plans to clarify this statement since the accident analysis simply assumes a leakage rate irrespective of the source of the leakage. (The staff notes that the TSTF-449 accident-induced leakage performance criteria imposes restrictions on how much leakage can come from specific sources when satisfying the various aspects of the performance criteria.)
Since similar comments apply to the discussion of the Limiting Condition for Operation (LCO) on page E3-8, please discuss your plans to modify this paragraph consistent with the comments above. In addition, discuss your plans to replace "SG leakage" on page E3-8 with "primary to secondary leakage" to make it consistent with the new terminology introduced in TSTF-449 (and your proposal on pages E2-3 and E2-4).
4.
In Question #17 of the November 7, 2006, RAI, the staff asked for clarification regarding the discussion in the Bases on maintaining tube integrity. The staffs concern was that the discussion should be clear about the need to maintain integrity of all tubes in service.
Since the ACTIONS in proposed TS 3.4.5 only directly address flawed tubes inadvertently left in service following an inspection, the Bases should clarify that integrity must be maintained for all tubes in service. The latest proposal, in the ACTIONS section on page E3-9, adds a phrase stating that the tube integrity requirement, applies to any SG tube; plugged or not plugged. This suggests that in order to operate the plant you will be required to demonstrate the integrity of even those tubes already removed from service due to flaws. Please discuss your plans to clarify this explanation in your Bases of the requirement to maintain tube integrity (i.e., applies to any SG tube, either inadvertently not plugged or left in service in accordance with the approved repair criteria).
5.
In Question #19 of the November 7, 2006, RAI, the staff noted that the entire paragraph on page E3-12 beginning with, Wastage-type defects....., was essentially replaced with TSTF-449. Your response proposes to delete the first sentence of the paragraph. Please discuss your plans to remove this paragraph from your Bases.
6.
In Question #20 of the November 7, 2006, RAI, the staff asked for clarification of the leakage sources used in an equation for calculating postulated steam line break leakage on page E3-13 in the proposed TS Bases. In your response, the title of the section containing this equation was changed to, Calculation of Accident Leakage for Voltage-Based Alternate Repair Criteria (ARC). This title does not match the calculation because the calculation includes postulated leakage from the W* ARC, which is not a voltage-based ARC. In addition, the title, Postulated steam line break (SLB) leakage for the equation on page E3-13 is misleading since it only represents postulated leakage associated with implementation of the GL 95-05 and W* ARC. Also on page E3-13, the definition of ARCGL 95-05" is not completely accurate because it is the leakage from predominantly axially oriented ODSCC indications as determined in accordance with the ARC, and from the results of the SG tube inspections. The proposal defines ARCGL 95-05" as the normal SLB leakage derived from ARC methods and the SG tube inspections.
Lastly, the final paragraph of this section (page E3-14) is not clear in that (1) the combined leak rate from all sources must be less than the leak rate limit (i.e., not just the leak rate from all ARC); and (2) the term above assumed leakage does not appear to be necessary. Please discuss your plans to clarify this paragraph.
7.
As a result of this review, the staff also noted the following editorial comments:
- a. Proposed TS 6.8.4.k.b.3 on page E2-19, refers to the Limiting Condition of Operation (LCO) 3.4.6.2. The staff notes that LCO 3.4.6.2 is actually called Limiting Condition for Operation, which is the terminology established in 10 CFR 50.36. Please discuss your plans to correct this typographical error.
- b. On page E2-20 (proposed TS 6.8.4.k.c.1), plugging limit should be replaced with repair criteria given the new terms used in TSTF-449.
c.
On page E2-21 (proposed TS 6.8.4.k.c.2) the first sentence is not needed since the repair criteria is in the next sentence, and below the top of the tubesheet (TTS) is not needed in the second sentence since the W* distance is defined below. (Please note if TTS is deleted, it should be redefined in proposed TS 6.8.4.k.c.2.a.)
- d. In the second sentence of the last full paragraph on page E3-12, the word indications seems unnecessary.
- e. In the second paragraph on page E3-13, the term or repaired should be removed since no repair methods are authorized for Sequoyah Unit 2.
8.
In Question #22 of the November 7, 2006, RAI, the staff indicated that the wording was not consistent with TSTF-449. As a result, you modified the wording; however, it is still inconsistent with TSTF-449 since it does not reflect that leakage may increase as a result of accident conditions and it refers to maximum normal operational leakage (rather than primary-to-secondary leakage). Lastly, it is still not clear whether your accident analysis assumes 1 gpm leakage from all SGs or 0.4 gpm from all SGs (see #22 in the previous RAI and #3 above). If your normal operational leakage limit is equal to your accident-induced leakage limit, please confirm that controls are in place to ensure that the accident-induced leakage limit is not exceeded as a result of possible increases in the normal operating leakage rate from higher loadings during postulated accident conditions.
That is, the leak rate observed during normal operation may increase under design basis accident loading conditions. As a result, it may be necessary to keep the normal operating leakage rate significantly below the normal operating leakage rate limit to avoid exceeding the accident-induced leakage limit in the event a postulated accident were to occur.
9.
On page E3-17 of your November 30, 2006, response, you refer to ARC SLB leakage.
The meaning of these statements is not clear since the accident analysis simply assumes a leakage rate irrespective of the source of the leakage. (The staff notes that the TSTF-449 accident-induced leakage performance criteria imposes restrictions on how much leakage can come from specific sources when satisfying the various aspects of the performance criteria.) Please discuss your plans to clarify these statements.
Mr. Karl W. Singer SEQUOYAH NUCLEAR PLANT Tennessee Valley Authority cc:
Mr. Ashok S. Bhatnagar, Senior Vice President Nuclear Operations Tennessee Valley Authority 6A Lookout Place 1101 Market Street Chattanooga, TN 37402-2801 Mr. Preston D. Swafford, Senior Vice President Nuclear Support Tennessee Valley Authority 6A Lookout Place 1101 Market Street Chattanooga, TN 37402-2801 Mr. Larry S. Bryant, Vice President Nuclear Engineering & Technical Services Tennessee Valley Authority 6A Lookout Place 1101 Market Street Chattanooga, TN 37402-2801 General Counsel Tennessee Valley Authority 6A West Tower 400 West Summit Hill Drive Knoxville, TN 37902 Mr. John C. Fornicola, Manager Nuclear Assurance Tennessee Valley Authority 6A Lookout Place 1101 Market Street Chattanooga, TN 37402-2801 Ms. Beth A. Wetzel, Manager Corporate Nuclear Licensing and Industry Affairs Tennessee Valley Authority 4X Blue Ridge 1101 Market Street Chattanooga, TN 37402-2801 Mr. Robert H. Bryan, Jr., General Manager Licensing and Industry Affairs Tennessee Valley Authority 4X Blue Ridge 1101 Market Street Chattanooga, TN 37402-2801 Mr. Randy Douet, Site Vice President Sequoyah Nuclear Plant Tennessee Valley Authority P.O. Box 2000 Soddy Daisy, TN 37384-2000 Mr. Glenn W. Morris, Manager Licensing and Industry Affairs Sequoyah Nuclear Plant Tennessee Valley Authority P.O. Box 2000 Soddy Daisy, TN 37384-2000 Mr. David A. Kulisek, Plant Manager Sequoyah Nuclear Plant Tennessee Valley Authority P.O. Box 2000 Soddy Daisy, TN 37384-2000 Senior Resident Inspector Sequoyah Nuclear Plant U.S. Nuclear Regulatory Commission 2600 Igou Ferry Road Soddy Daisy, TN 37379 Mr. Lawrence E. Nanney, Director Division of Radiological Health Dept. of Environment & Conservation Third Floor, L and C Annex 401 Church Street Nashville, TN 37243-1532 County Mayor Hamilton County Courthouse Chattanooga, TN 37402-2801 Ms. Ann P. Harris 341 Swing Loop Road Rockwood, TN 37854