ML090230613
| ML090230613 | |
| Person / Time | |
|---|---|
| Site: | Byron, Braidwood  |
| Issue date: | 02/05/2009 |
| From: | David M Plant Licensing Branch III |
| To: | Pardee C Exelon Nuclear |
| david marshall NRR/DORL 415-1547 | |
| References | |
| TAC MD8179, TAC MD8180, TAC MD8181, TAC MD8182 | |
| Download: ML090230613 (17) | |
Text
\\.~p..~ ~EGIJI _
UNITED STATES
~v
"'I~
"'~,
,.0"'....
NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555*0001
<l:
0
~
rJl
~
February 5, 2009
~
~
'C'/
~
1-']
...0
- ~
Mr. Charles G. Pardee President and Chief Nuclear Officer Exelon Nuclear 4300 Winfield Road Warrenville, IL 60555
SUBJECT:
BRAIDWOOD STATION, UI\\IITS 1 AND 2, AND BYRON STATION, UNIT NOS. 1 AND 2 -ISSUANCE OF AMENDMENTS RE: REVISED APPLICATION OF ALTERNATIVE SOURCE TERM (TAC NOS. MD8179, MD8180, MD8181, AND MD8182)
Dear Mr. Pardee:
The Nuclear Regulatory Commission (NRC, the Commission) has issued the enclosed Amendment No. 155to Facility Operating License No. NPF-72 and Amendment No. 155to Facility Operating License No. NPF-77 for the Braidwood Station, Units 1 and 2 (Braidwood),
and Amendment No. 160 to Facility Operating License No. NPF-37 and Amendment No. 160 to Facility Operating License No. NPF-66 for the Byron Station, Unit Nos. 1 and 2 (Byron),
respectively. The amendments are in response to your application dated February 21, 2008.
The amendments approve changes to the current licensing basis for Braidwood and Byron associated with the application of an alternative source term (AST) methodology, previously approved by the NRC staff. Specifically, the amendments approve removing credit for the control room ventilation system recirculation prefilters and reducing the assumed control room unfiltered inleakage in the AST analyses.
A copy of the Safety Evaluation is enclosed. The Notice of Issuance will be included in the Commission's biweekly Federal Register notice.
Sincerely,
~--\\"\\
.t..',7l. t,~.
tU?lr.d.f{
/
~all J. David, S ior Qect Manager
~1:~hLicenSing Branch 111-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. STI\\I 50-456, STN 50-457, STN 50-454, and STN 50-455
Enclosures:
- 1. Amendment No. 155 to NPF-72
- 2. Amendment No. 155 to NPF-77
- 3. Amendment 1\\10. 160 to NPF-37
- 4. Amendment No. 160 to NPF-66
- 5. Safety Evaluation cc w/encls: Distribution via ListServ
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555*0001 EXELOI\\J GENERATION COMPANY, LLC DOCKET NO. STN 50-456 BRAIDWOOD STATION, UNIT 1 AMENDMENT TO FACILITY OPERATING LICENSE Amendment No. 155 License No. NPF-72
- 1.
The Nuclear Regulatory Commission (the Commission) has found that:
A.
The application for amendment by Exelon Generation Company, LLC (the licensee) dated February 21,2008, 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 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 to authorize revision of the current licensing basis for Braidwood Station, Unit 1, as set forth in the application for amendment by the licensee, dated February 21,2008. The licensee shall remove credit for the control room ventilation system recirculation prefilters and shall reduce, from 1000 cubic feet per minute (cfm) to 500 cfm, the assumed control room unfiltered inleakage in the current alternative source term analyses.
- 2
- 3.
This license amendment is effective as of the date of its issuance and shall be implemented within 60 days of the date of issuance.
FOR THE NUCLEAR REGULATORY COMMISSION
~wg Russell Gibbs, Chief Plant Licensing Branch 111-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Date of Issuance: February 5, 2009
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 EXELON GENERATION COMPANY, LLC DOCKET NO. STN 50-457 BRAIDWOOD STATION, UNIT 2 AMENDMENT TO FACILITY OPERATING LICENSE Amendment No. 155 License No. NPF-77
- 1.
The Nuclear Regulatory Commission (the Commission) has found that:
A.
The application for amendment by Exelon Generation Company, LLC (the licensee) dated February 21,2008, 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 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 to authorize revision of the current licensing basis for Braidwood Station, Unit 2, as set forth in the application for amendment by the licensee, dated February 21,2008. The licensee shall remove credit for the control room ventilation system recirculation prefilters and shall reduce, from 1000 cubic feet per minute (cfm) to 500 cfm, the assumed control room unfiltered inleakage in the current alternative source term analyses.
- 2
- 3.
This license amendment is effective as of the date of its issuance and shall be implemented within 60 days of the date of issuance.
F~LE~ATORYCOMMISSION Russell Gibbs, Chief Plant Licensing Branch 111-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Date of Issuance: February 5, 2009
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 EXELON GENERATION COMPANY, LLC DOCKET NO. STN 50-454 BYRON STATION, UNIT NO.1 AMENDMENT TO FACILITY OPERATING LICENSE Amendment No. 160 License No. I'JPF-37
- 1.
The Nuclear Regulatory Commission (the Commission) has found that:
A.
The application for amendment by Exelon Generation Company, LLC (the licensee) dated February 21, 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 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 to authorize revision of the current licensing basis for Byron Station, Unit No.1, as set forth in the application for amendment by the licensee, dated February 21, 2008. The licensee shall remove credit for the control room ventilation system recirculation prefilters and shall reduce, from 1000 cubic feet per minute (cfm) to 500 cfm, the assumed control room unfiltered inleakage in the current alternative source term analyses.
- 2
- 3.
This license amendment is effective as of the date of its issuance and shall be implemented within 60 days of the date of issuance.
FOR THE NUCLEAR REGULATORY COMMISSION fl;unCte ~
Russell Gibbs, Chief Plant Licensing Branch 111-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Date of Issuance: February 5, 2009
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 EXELON GENERATION COMPANY, LLC DOCKET NO. STN 50-455 BYRON STATION, UNIT NO.2 AMENDMENT TO FACILITY OPERATING LICENSE Amendment No. 160 License No. NPF-66
- 1.
The Nuclear Regulatory Commission (the Commission) has found that:
A.
The application for amendment by Exelon Generation Company, LLC (the licensee) dated February 21,2008, 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 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 to authorize revision of the current licensing basis for Byron Station, Unit No.2, as set forth in the application for amendment by the licensee, dated February 21,2008. The licensee shall remove credit for the control room ventilation system recirculation prefilters and shall reduce, from 1000 cubic feet per minute (cfm) to 500 cfm, the assumed control room unfiltered inleakage in the current alternative source term analyses.
- 2
- 3.
This license amendment is effective as of the date of its issuance and shall be implemented within 60 days of the date of issuance.
FOR THE NUCLEAR REGULATORY COMMISSION
~M Russell Gibbs, Chief Plant Licensing Branch 111-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Date of Issuance: February 5, 2009
~p.1\\ REGU{
UNITED STATES
~v\\.
"I;,
- r.
0.,.
NUCLEAR REGULATORY COMMISSION
.L 0
(')
WASHINGTON, D.C. 20555-0001
~
<II
~
~
~
'I'/~
Of:'
')****1< ~ SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 155 TO FACILITY OPERATING LICENSE NO. NPF-72, AMENDMENT NO. 155 TO FACILITY OPERATING LICENSE NO. NPF-77, AMENDMENT NO. 160 TO FACILITY OPERATING LICENSE NO. NPF-37, AND AMENDMENT NO. 160 TO FACILITY OPERATING LICENSE NO. NPF-66 EXELON GENERATION COMPANY, LLC BRAIDWOOD STATION, UNITS 1 AND 2 BYRON STATION, UNIT NOS. 1 AND 2 DOCKET NOS. STN 50-456, STN 50-457, STN 50-454, AND STN 50-455
1.0 INTRODUCTION
By letter to the Nuclear Regulatory Commission (NRC, the Commission) dated February 21, 2008 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML080520514), Exelon Generation Company, LLC (the licensee) requested a revision to the current licensing basis associated with the application of a previously-approved alternative source term (AST) methodology. This revision was requested because of a misapplication of control room (CR) ventilation (VC) system prefilter efficiency in the current AST analyses for Braidwood Station, Units 1 and 2 (Braidwood), and for Bryon Station, Unit Nos.1 and 2 (Byron).
The proposed revised AST methodology removes credit that was inappropriately taken for the prefilters in the current Braidwood and Byron AST analyses, as well as, reduces an additional conservatism in the current analyses. The revised analyses provide the new basis for the CR doses associated with the relevant design-basis accidents (DBAs).
2.0 BACKGROUND
The current AST analyses for Braidwood and Byron were submitted on February 15, 2005 (ADAMS Accession No. ML050560102). The licensee performed radiological consequence analyses for the following six DBAs that result in CR and offsite exposure.
Loss-of-Coolant Accident (LOCA)
Fuel-Handling Accident (FHA)
Control Rod Ejection Accident (CREA)
Locked-Rotor Accident (LRA)
Main Steamline Break (MSLB)
Steam Generator Tube Rupture (SGTR)
- 2 The February 15, 2005, submittal also included changes to the Braidwood and Byron technical specifications (TSs) and associated bases to reflect implementation of AST assumptions in accordance with Title 10 of the Code of Federal Regulations (10 CFR) Section 50.67, with the exception that Technical Information Document (TID) 14844, Calculation of Distance Factors for Power and Test Reactors Sites, would continue to be used as the radiation dose basis for equipment qualification. The NRC staff approved these changes by letter dated September 8, 2006 (ADAMS Accession No. ML062340420), as Braidwood Amendment No. 140 and Byron Amendment No. 147.
This safety evaluation discusses the impact of the proposed changes on the previously-analyzed radiological consequences resulting from the aforementioned DBAs and the acceptability of the results of the revised analyses.
3.0 REGULATORY EVALUATION
The regulatory requirements against which the NRC staff performed its review of the licensee's February 21, 2008, request are the following:
10 CFR 50.67, Accident source term 10 CFR Part 50 Appendix A, General Design Criterion 19 (GDC 19), Control room 10 CFR 50.59, Changes, tests, and experiments The NRC staff used the regulatory guidance provided in the following documents in performing its review:
Regulatory Guide (RG) 1.183, Alternative Radiological Source Terms for Evaluating Design Basis Accidents at Nuclear Power Reactors, July 2000 RG 1.195, Methods and Assumptions for Evaluating Radiological Consequences of Design Basis Accidents (DBA) at Light-Water Nuclear Power Reactors, May 2003 Standard Review Plan (SRP) 15.0.1, Radiological Consequence Analyses Using Alternative Source Terms, Revision 0, July 2000 The NRC staff also considered relevant information in the Braidwood and Byron Updated Final Safety Analysis Report (UFSAR), TS, and applicable previous Braidwood and Byron licensing actions.
4.0 TECHNICAL EVALUATION
Following the implementation of Braidwood Amendment No. 140 and Byron Amendment No. 147, the licensee identified that a misapplication of a VC system filter efficiency was incorporated into the AST analyses. Specifically, Braidwood and Byron UFSAR Table 6.4-1a, Principal Assumptions Used in Control Room Habitability Calculations, documents an 80 percent particulate filter efficiency for the CR recirculation flow filter; and, therefore, the 80 percent efficiency was credited in the AST analyses as documented in Section 4.4 of
- 3 to the licensee's February 15, 2005, submittal. The filter in question is the system prefilter, which is designed to remove larger particulate matter and reduce excessive particulate loading of the downstream ventilation components such as charcoal filters, cooling and heating coils, etc. However, this prefilter has no approved testing methodology. Since the prefilter cannot be tested, credit cannot be taken for the 80 percent particulate efficiency of this prefilter.
Based on the determination that credit cannot be taken for the prefilter, the licensee revised the Braidwood and Byron AST analyses to remove credit for these prefilters.
In addition to removing the assumption that the prefilters remove 80 percent of the particulates, the licensee assumed 500 cubic feet per minute (cfm) of unfiltered inleakage for the duration of each DBA event. This is a reduction from the current assumption of 1000 cfm. In its February 21, 2008, request, the licensee stated that the reason for this change is to offset the increase in dose associated with the removal of the prefilter credit. The new assumption of 500 cfm of unfiltered inleakage bounds the maximum measured inleakage value of 68 standard cubic feet per minute (scfm) for Byron and 29.3 scfm for Braidwood. The CR unfiltered inleakage was measured by means of tracer gas testing based on the American Society for Testing and Materials (ASTM) standard ASTM E-741-00, Standard Test Method for Determining Air Change in a Single Zone by Means of a Tracer Gas Dilution. The tests were completed on November 1,2004, for Byron and on November 7,2004, for Braidwood. The NRC staff finds that the licensee's assumption of 500 cfm CR unfiltered inleakage is conservative, compared to the actual measured values, and is, therefore, acceptable.
The licensee stated that the effect of removing the VC system prefilter credit and reducing the unfiltered air inleakage only affects the CR dose. These changes in the analyses assumptions do not affect the effluents released offsite and, therefore, do not affect the calculated exclusion area boundary (EAB) and low-population zone (LPZ) doses. Therefore, a revision to the offsite doses resulting from the six DBAs analyzed is not needed. Based on the above discussion, the NRC staff finds that the original EAB and LPZ doses calculated in the radiological consequence analyses for the six DBAs, as approved by its September 8, 2006, letter, remain applicable for Braidwood and Byron.
In the current AST analyses, the prefilters were credited to provide the function of particulate fission product removal. In its February 21, 2008, request, the licensee stated that only those DBAs that result in fuel failure and generation of particulate activity result in an increase in overall CR dose consequence. The analyses resulting in an increase in CR dose radiological consequences, as a result of the revised assumptions, are the LOCA, LRA, and CREA analyses. As shown in Table 1, the resulting CR doses are still within the regulatory limits of 10 CFR 50.67 and GDC 19. The other three accidents analyzed - FHA, MSLB, and SGTR assume gaseous releases only and do not involve particulate activity. Since these accidents do not involve particulate activity, the analyses implementing the revised assumptions result in an overall decrease in the CR dose radiological consequences, because of the reduction in assumed CR unfiltered inleakage.
The licensee reviewed the revised doses resulting from the change in AST assumptions against the 10 CFR 50.59 criteria for an increase in the consequences of an accident previously evaluated. According to Nuclear Energy Institute (NEI) 96-07, Guidelines for 10 CFR 50.59 Evaluations, Revision 1, a change that results in an increase in consequences of more than
- 4 10 percent of the difference between the current calculated value and the regulatory guideline value should be considered more than a minimal increase in the consequences of an accident previously evaluated in the UFSAR. The dose increases associated with the revised LOCA, LRA, and CREA analyses were determined by the licensee to exceed the 10 percent increase criterion for more than a minimal increase in consequences. The doses associated with the revised FHA, MSLB, and SGTR analyses decrease and did not exceed the 10 percent increase criterion. Therefore, as part of its 10 CFR 50.59 process, the licensee has submitted the revised LOCA, LRA, and CREA analyses and the resulting new CR doses to the NRC staff for review and approval prior to implementing the proposed change in the AST analyses. The CR doses associated with the revised FHA, MSLB, and SGTR analyses decrease and, therefore, remain conservative. However, the licensee stated that it will revise the FHA, MSLB, and SGTR analyses to reflect the removal of the 80 percent credit for the VC recirculation prefilter and reduced unfiltered inleakage assumptions for consistency among all the AST analyses.
To verify the licensee's radiological consequence analyses, the NRC staff performed confirmatory radiological consequence dose analyses for the LOCA, LRA, and CREA. The NRC staff's results are also within the dose criteria specified in 10 CFR 50.67 and GOC 19. Although the NRC staff performed its independent radiological consequence dose analysis as a means of confirming the licensee's results, the NRC staff's acceptance is based on the licensee's analyses. The results of the licensee's radiological consequence analyses for CR doses for the LOCA, LRA, and CREA analyses are provided in Table 1, and the major parameters and assumptions used by the licensee, and acceptable to the NRC staff, are listed in Table 2. The radiological consequences at the EAB, at the LPZ, and in the CR as calculated by the licensee are all within the dose criteria specified in 10 CFR 50.67 and GOC 19, and are, therefore, acceptable.
The NRC staff has evaluated the assumptions, inputs, and methods used by the licensee to assess the radiological impacts of implementation of revised AST analyses at Braidwood and Byron. The NRC staff further concludes that the plant site and the dose-mitigating engineered safety features remain acceptable with respect to the radiological consequences of postulated OBAs because, as set forth above, the calculated total effective dose equivalent (TEOE) at the EAB, at the LPZ outer boundary, and in the CR meet the exposure guideline values specified in 10 CFR 50.67 and GOC 19, as well as applicable acceptance criteria denoted in RG 1.183 and SRP Section 15.0.1. Therefore, the NRC staff finds the licensee's proposed changes acceptable with respect to the radiological consequences of DBAs.
5.0 STATE CONSULTATION
In accordance with the Commission's regulations, the Illinois State official was notified of the proposed issuance of the amendment. The State official had no comments.
6.0 ENVIRONMENTAL CONSIDERATION
The amendments change requirements with respect to installation or use of a facility's components located within the restricted area, as defined in 10 CFR Part 20. The NRC staff has determined that the amendments involve 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
- 5 Commission has previously issued a proposed finding that the amendments involve no significant hazards consideration, and there has been no public comment on such finding (73 FR 31720; June 3, 2008). Accordingly, the amendments meet 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 amendments.
7.0 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 amendments will not be inimical to the common defense and security or to the health and safety of the public.
Principal Contributor: D. Duvigneaud, NRR Date: February 5, 2009
Table 1 Licensee Calculated DBA Radioloqical Consequences Accident Original CR Dose (rem TEDE)
Regulatory CR Dose Limit (rem TEDE)
LOCA 4.0 4.782 5
LRA 2.529 2.790 5
CREA 2.549 4.538 5
Table 2 Control Room Analysis Assumptions Parameter CR volume, fe Recirculation flow rate, cfm Recirculation filter efficiency, percent Elemental Organic Emergency makeup flow rate, cfm Makeup filter efficiency, percent Elemental Organic Particulate Delay to switch to emergency mode, min Unfiltered inleakage assumption, cfm CR occupancy factors 0-24 hr 1-4 days 4-30 days CR breathing rate, m3/sec Value 200,000 43,500 +/- 10 percent 90 90 6,000 +/- 10 percent 95 95 99 30 500 1.0 0.6 0.4 3.5x10-4
- SE Memo Date NRR-058 OFFICE LPL3-2/PM LPL3-2/LA DRA/AADB/BC OGC/ NLO LPL3-2/BC NAME MDavid EWhitt RTaylor*
BHarris RGibbs DATE 1/29/09 1/29/09 01/05/09 2/2/09 2/5/09