ML080720526
| ML080720526 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 03/31/2008 |
| From: | Wang A NRC/NRR/ADRO/DORL/LPLIV |
| To: | Entergy Operations |
| Wang A, NRR/DORL/LPL4, 301-415-1445 | |
| Shared Package | |
| ML080720523 | List: |
| References | |
| TAC MD6933 | |
| Download: ML080720526 (10) | |
Text
March 31, 2008 Vice President, Operations Arkansas Nuclear One Entergy Operations, Inc.
1448 S.R. 333 Russellville, AR 72802
SUBJECT:
ARKANSAS NUCLEAR ONE, UNIT NO. 2 - ISSUANCE OF AMENDMENT RE:
TECHNICAL SPECIFICATIONS 3.6.2.2, CONTAINMENT SUMP BUFFERING AGENT TRISODIUM PHOSPHATE (TSP) (TAC NO. MD6933)
Dear Sir or Madam:
The Commission has issued the enclosed Amendment No. 278 to Renewed Facility Operating License No. NPF-6 for Arkansas Nuclear One, Unit No. 2. The amendment consists of changes to the Technical Specifications (TS) in response to your application dated October 5, 2007, as supplemented by letter dated February 19, 2008.
The amendment revises TS 3.6.2.2, Containment Sump Buffering Agent Trisodium Phosphate (TSP), and its associated Surveillance Requirement 4.6.2.2 to replace references to TSP with the sodium tetraborate (NaTB) buffering agent. The required volume of buffering agent has also been changed to reflect the new buffer. In addition, the title has been changed to remove the reference to TSP.
A copy of our related Safety Evaluation is also enclosed. The Notice of Issuance will be included in the Commission's next biweekly Federal Register notice.
Sincerely,
/RA/
Alan B. Wang, Project Manager Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-368
Enclosures:
- 1. Amendment No. 278 to NPF-6
- 2. Safety Evaluation cc w/encls: See next page
Pkg ML080720523 (Amdt. ML080720526, License/TS Pgs ML080720534) (*) SE input memo OFFICE NRR/LPL4/PM NRR/LPL4/LA DCI/CSGB/BC OGC - NLO NRR/LPL4/BC NAME AWang ABW via email JBurkhardt AHiser (*)
MSpencer (**)
THiltz DATE 3/13/08 3/31/08 3/10/08 3/21/08 3/31/08
Arkansas Nuclear One (2/25/08) cc:
Senior Vice President Entergy Nuclear Operations P.O. Box 31995 Jackson, MS 39286-1995 Vice President, Oversight Entergy Nuclear Operations P.O. Box 31995 Jackson, MS 39286-1995 Senior Manager, Nuclear Safety
& Licensing Entergy Nuclear Operations P.O. Box 31995 Jackson, MS 39286-1995 Senior Vice President
& Chief Operating Officer Entergy Operations, Inc.
P.O. Box 31995 Jackson, MS 39286-1995 Associate General Counsel Entergy Nuclear Operations P.O. Box 31995 Jackson, MS 39286-1995 Manager, Licensing Entergy Operations, Inc.
Arkansas Nuclear One 1448 SR 333 Russellville, AR 72802 Section Chief, Division of Health Radiation Control Section Arkansas Department of Health and Human Services 4815 West Markham Street, Slot 30 Little Rock, AR 72205-3867 Section Chief, Division of Health Emergency Management Section Arkansas Department of Health and Human Services 4815 West Markham Street, Slot 30 Little Rock, AR 72205-3867 Pope County Judge Pope County Courthouse 100 W. Main Street Russellville, AR 72801 Senior Resident Inspector U.S. Nuclear Regulatory Commission P.O. Box 310 London, AR 72847 Regional Administrator, Region IV U.S. Nuclear Regulatory Commission 611 Ryan Plaza Drive, Suite 400 Arlington, TX 76011-8064
ENTERGY OPERATIONS, INC.
DOCKET NO. 50-368 ARKANSAS NUCLEAR ONE, UNIT NO. 2 AMENDMENT TO RENEWED FACILITY OPERATING LICENSE Amendment No. 278 Renewed License No. NPF-6
- 1.
The Nuclear Regulatory Commission (the Commission) has found that:
A.
The application for amendment by Entergy Operations, Inc. (the licensee), dated October 5, 2007, as supplemented by letter dated February 19, 2008, complies with the standards and requirements of the Atomic Energy Act of 1954, as amended (the Act), and the Commission's rules and regulations set forth in 10 CFR Chapter I; B.
The facility will operate in conformity with the application, the provisions of the Act, and the rules and regulations of the Commission; C.
There is reasonable assurance (i) that the activities authorized by this amendment can be conducted without endangering the health and safety of the public, and (ii) that such activities will be conducted in compliance with the Commission's regulations; D.
The issuance of this license amendment will not be inimical to the common defense and security or to the health and safety of the public; and E.
The issuance of this amendment is in accordance with 10 CFR Part 51 of the Commission's regulations and all applicable requirements have been satisfied.
- 2.
Accordingly, the license is amended by changes to the Technical Specifications as indicated in the attachment to this license amendment, and Paragraph 2.C.(2) of Renewed Facility Operating License No. NPF-6 is hereby amended to read as follows:
(2)
Technical Specifications The Technical Specifications contained in Appendix A, as revised through Amendment No. 278, are hereby incorporated in the renewed license.
The licensee shall operate the facility in accordance with the Technical Specifications
- 3.
The license amendment is effective as of its date of issuance and shall be implemented following completion of the 2R19 refueling outage in spring 2008.
FOR THE NUCLEAR REGULATORY COMMISSION
/RA/
Thomas G. Hiltz, Chief Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation
Attachment:
Changes to the Renewed Facility Operating License No. NPF-6 Technical Specifications Date of Issuance: March 31, 2008
ATTACHMENT TO LICENSE AMENDMENT NO. 278 RENEWED FACILITY OPERATING LICENSE NO. NPF-6 DOCKET NO. 50-368 Replace the following pages of the Renewed Facility Operating License No. NPF-6 and Appendix A Technical Specifications with the attached revised pages. The revised pages are identified by amendment number and contain marginal lines indicating the areas of change.
Operating License REMOVE INSERT Technical Specifications REMOVE INSERT 3/4 6-12 3/4 6-12
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 278 TO RENEWED FACILITY OPERATING LICENSE NO. NPF-6 ENTERGY OPERATIONS, INC.
ARKANSAS NUCLEAR ONE, UNIT NO. 2 DOCKET NO. 50-368
1.0 INTRODUCTION
By application dated October 5, 2007 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML072890085), as supplemented by letter dated February 19, 2008 (ADAMS Accession Nos. ML080580200), Entergy Operations, Inc. (the licensee),
requested changes to the Technical Specifications (TS) for Arkansas Nuclear One, Unit No. 2 (ANO-2). The supplemental letter dated February 19, 2008, provided additional information that clarified the application, did not expand the scope of the application as originally noticed, and did not change the U.S. Nuclear Regulatory Commission (NRC) staff's original proposed no significant hazards consideration determination as published in the Federal Register on November 6, 2007 (72 FR 62688).
The proposed changes would revise TS 3.6.2.2, Containment Sump Buffering Agent Trisodium Phosphate (TSP) and its associated Surveillance Requirement 4.6.2.2 to replace references to TSP with the sodium tetraborate (NaTB) buffering agent. The required volume of buffering agent has also been changed to reflect the new buffer. In addition, the title has been changed to remove the reference to TSP.
2.0 REGULATORY EVALUATION
In Section 50.36, Technical specifications, of Title 10 of the Code of Federal Regulations (10 CFR), the Commission established its regulatory requirements related to the content of TS.
Pursuant to 10 CFR 50.36(d), TS are required to include items in the following five specific categories related to station operation: (1) safety limits, limiting safety system settings, and limiting control settings; (2) limiting conditions for operation; (3) surveillance requirements; (4) design features; and (5) administrative controls.
The NRC staff review addresses the impact of the proposed change from TSP to NaTB on the containment sump performance, especially potential chemical effects impacts on sump screen blockage and head loss.
The containment sump (also known as the emergency recirculation sump) is part of the emergency core cooling system (ECCS). Every nuclear power plant is required by 10 CFR 50.46, Acceptance criteria for emergency core cooling systems for light-water nuclear power reactors, to have an ECCS to mitigate a design-basis accident. Paragraph 10 CFR 50.46(a)(1)(i) states, in part, that each pressurized light-water nuclear power reactor... must be provided with an [ECCS] that must be designed so that its calculated cooling performance following postulated loss-of-coolant accidents [LOCA] conforms to the criteria set forth in paragraph (b) of this section. 10 CFR 50.46(b)(5), Long-term cooling, states, [a]fter any calculated successful initial operation of the ECCS, the calculated core temperature shall be maintained at an acceptably low value and decay heat shall be removed for the extended period of time required by the long-lived radioactivity remaining in the core.
In addition, the NRC staff utilized the following regulatory guidance in performing this review:
NUREG-0800, Section 6.5.2, Containment Spray as a Fission Product Cleanup System, which states, in part, that long-term iodine retention may be assumed only when the equilibrium sump solution pH, after mixing and dilution with the primary coolant and ECCS injection, is above 7.
Regulatory Guide 1.82, Revision 3, Water Sources for Long-Term Recirculation Cooling Following a Loss-of-Coolant Accident, Section 1.1.2, which states, in part, that debris that could accumulate on the sump screen should be minimized.
3.0 TECHNICAL EVALUATION
ANO-2 proposed to replace the TSP with NaTB in the containment. The current ANO-2 containment materials include sources of phosphate (from the TSP) and calcium (from insulation materials). The combination of these materials is expected to form a calcium phosphate precipitate in a post-LOCA containment pool, that could adversely impact sump performance.
The NRC and the nuclear industry jointly sponsored Integrated Chemical Effects Tests (ICET) to investigate potential chemical effects in representative post-LOCA containment environments.
The ICET series was conducted by Los Alamos National Laboratory, at the University of New Mexico. ICET #3 showed that the presence of calcium silicate (cal-sil) insulation and TSP in a simulated post-LOCA containment pool rapidly formed a calcium phosphate precipitate. NRC Information Notice (IN) 2005-26, Results of Chemical Effects Head Loss Tests in a Simulated PWR [Pressurized-Water Reactor] Sump Pool Environment, along with IN 2005-26, Supplement 1, Additional Results of Chemical Effects Tests in a Simulated PWR Sump Pool Environment, discussed results from NRC-sponsored head-loss testing at Argonne National Laboratory (ANL). These ANL test results demonstrated that substantial head loss can occur if sufficient calcium phosphate is produced in a simulated post-LOCA containment pool and is transported to a pre-existing bed on the containment sump screen. To preclude this occurrence, ANO-2 proposes to remove TSP from the ANO-2 containment.
Post-LOCA containment pool buffering is primarily required to reduce the release of iodine fission products from the pool to the containment atmosphere as iodine gas, in order to control the radiological consequences of the accident. Maintaining a pH (potential of hydrogen) above 7 prevents significant amounts of iodine, released from fuel failures and dissolved in the recirculation water, from converting to a volatile form and evolving into the containment
atmosphere. Since the ability to control pH in a post-LOCA containment pool is affected by removal of TSP, ANO-2 proposes to use NaTB as the new buffering agent.
The method of introducing the buffer material to the post-LOCA environment is the same for NaTB as it is for TSP. The existing three TSP baskets would be used to hold the NaTB. The licensee confirmed that the baskets are adequately sized to hold the required amount of NaTB.
The minimum allowable amount of NaTB was determined by the licensee. Their analyses included consideration of minimum and maximum quantities of boron and borated water. The analyses also included conservative amounts of hydrochloric and nitric acids resulting from radiolysis of air and water, radiolysis of chloride-bearing electrical cable insulation, and jacketing.
For instance, the amount of acid generated from cable insulation was conservatively determined by using the weight of all cable whether or not it was in an enclosure, tray, or conduit, and by using the weight of all the nonconducting cable material whether or not it is exposed to the containment atmosphere. The licensee determined that the minimum amount of NaTB required to maintain the minimum sump pH of 7.0 is 15,000 pounds. Based on information provided by the licensees letter dated February 19, 2008, the NRC staff performed an evaluation to confirm the licensees pH calculations. The NRC staff reviewed the licensees methodology, assumptions, and performed hand calculations to verify the resulting pH value after 30 days.
The NRC staff concluded that the licensees methodology and calculations are conservative.
The NRC staffs independent verification demonstrated the containment sump pH would remain greater than or equal to 7 for at least 30 days post-LOCA with the quantities of NaTB described above.
The NRC staff reviewed the licensees regulatory and technical analyses related to the impact of the proposed change from TSP to NaTB on containment sump performance, particularly the potential impact from chemical effects on sump screen blockage and head-loss aspects of design-basis accidents. The licensees evaluation determined that NaTB is an acceptable alternative to TSP based on industry testing of buffers outlined in WCAP-16596-NP, Evaluation of Alternative Emergency Core Cooling System Buffering Agents, and through plant-specific application of the chemical model developed in WCAP-16530-NP, Evaluation of Post-Accident Chemical Effects in Containment Sump Fluids to Support [Generic Safety Issue] GSI-191.
Under the existing TSP conditions, the model predicts approximately 807 pounds of chemical precipitates. For the proposed NaTB condition using conservative values for pH, temperature, and quantities of contributing materials, the model predicts approximately 62 pounds of chemical precipitates. Based on the WCAP-16530-NP model, the switch from TSP to NaTB results in a reduction in the mass of predicted chemical precipitates of approximately 745 pounds. In addition, the switch to NaTB eliminates the formation of calcium phosphate precipitates which have been shown to have severe head-loss implications at early stages of a simulated post-LOCA event (see NRC IN 2005-26).
Based on verification calculations, the NRC staff finds that replacing the TSP containment sump buffer with NaTB in the quantities specified by the licensee will provide acceptable containment sump buffering such that the sump pH will be maintained in an acceptable range under LOCA conditions.
Although potential chemical effects exist with the use of NaTB in the ANO-2 containment, the NRC staff determined that chemical effects at ANO-2 will be of significantly lower quantity and will be delayed to a more favorable time with NaTB compared to TSP. Based on the proper buffering to be provided by NaTB in the quantities specified and the relative reduction in the
mass of chemical precipitates in the case of a LOCA, the NRC staff finds that the replacement of TSP with NaTB in the quantities specified is acceptable and therefore, the proposed TS changes are acceptable.
The NRC staff also concludes the removal of the reference to TSP in the title is editorial in nature and therefore, is acceptable.
The NRC staff concludes that changing buffer materials from TSP to NaTB at ANO-2 will result in an improved situation from a chemical effects standpoint. However, despite the significant reduction in the total amount of chemical precipitates, the WCAP-16530-NP model still predicts approximately 62 pounds of precipitate under NaTB conditions. The licensee will still need to demonstrate acceptable ECCS performance under the proposed NaTB conditions in order to fully resolve GSI-191 for ANO-2. The NRC staff will be reviewing the licensees approach to resolving potential chemical effects associated with NaTB as part of the GSI-191 resolution process.
4.0 STATE CONSULTATION
In accordance with the Commission's regulations, the Arkansas State official was notified of the proposed issuance of the amendment. The State official had no comments.
5.0 ENVIRONMENTAL CONSIDERATION
The amendment changes a requirement with respect to installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20. The NRC staff has determined that the amendment involves no significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure. The Commission has previously issued a proposed finding that the amendment involves no significant hazards consideration, and there has been no public comment on such finding published in the Federal Register on November 6, 2007 (72 FR 62688). Accordingly, the amendment meets the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9).
Pursuant to 10 CFR 51.22(b), no environmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendment.
6.0 CONCLUSION
The Commission has concluded, based on the considerations discussed above, that: (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public.
Principal Contributor: E. Wong Date: March 31, 2008