RS-03-051, Additional Information Supporting Request for License Amendment Regarding Minimum Critical Power Ratio Safety Limit

Additional Information Supporting Request for License Amendment Regarding Minimum Critical Power Ratio Safety Limit

ML030770724
Person / Time
Site:	Dresden
Issue date:	03/07/2003
From:	Simpson P Exelon Generation Co, Exelon Nuclear
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
RS-03-051
Download: ML030770724 (18)

Text

Exelknm, Exelon Generation wwwexeloncorp corn Nuclear 4300 Winfield Road Warrenville, IL 60555 RS-03-051 March 7, 2003 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Dresden Nuclear Power Station, Unit 2 Facility Operating License No. DPR-19 NRC Docket No. 50-237

Subject:

Additional Information Supporting the Request for License Amendment Regarding Minimum Critical Power Ratio Safety Limit

Reference:

Letter from P. R. Simpson (Exelon Generation Company, LLC) to U. S. NRC, "Request for License Amendment Regarding Minimum Critical Power Ratio Safety Limit," dated January 31, 2003 In the referenced letter, Exelon Generation Company (EGC), LLC, requested a change to the Technical Specifications (TS) of Facility Operating License Number DPR-19 for Dresden Nuclear Power Station (DNPS), Unit 2. In a February 13, 2003, telephone conference call between representatives of EGC and members of the NRC, the NRC requested additional information regarding this proposed change. Attachment A to this letter provides the requested information.

As noted in the referenced letter, in December 2002, Global Nuclear Fuel (GNF) discovered an error in the original calculation for the DNPS, Unit 2 Cycle 18 TS safety limit for the minimum critical power ratio. As noted in Attachment A to this letter, GNF has evaluated this error and determined that it constitutes a reportable condition in accordance with 10 CFR 21, "Reporting of Defects and Noncompliance." Specifically, 10 CFR 21.3, "Definitions," states, under the section entitled "Defect," that a condition is reportable if it could contribute to exceeding a safety limit as defined in the TS. Since this condition was described to the NRC by EGC in the referenced letter, GNF and EGC have determined that, with the exception of a description of the cause and corrective actions for the error, the referenced letter fulfills GNF's reporting requirements in accordance with 10 CFR 21.21, "Notification of a failure to comply or existence of a defect and its evaluation," paragraph (d)(2). With the inclusion of the cause and corrective action information in Attachment A to this letter, the reporting requirements in accordance with 10 CFR 21 are fully satisfied.

Some of the information in Attachment A is proprietary information to GNF, and EGC requests that it be withheld from public disclosure in accordance with 10 CFR 2.790(a)(4), "Public inspections, exemptions, requests for withholding." This information is indicated with double

/A-Pol

March 7, 2003 U. S. Nuclear Regulatory Commission Page 2 brackets. Attachment B provides the affidavit supporting the request for withholding the proprietary information in Attachment A from public disclosure, as required by 10 CFR 2.790(b)(1). Attachment C contains a non-proprietary version of Attachment A.

Should you have any questions concerning his letter, please contact Mr. Allan R. Haeger at (630) 657-2807.

Respectfully, P4.

P. R. Simpson Manager - Licensing Mid-West Regional Operating Group Attachments:

Affidavit Attachment A:

Attachment B:

Attachment C:

Additional Information Supporting the Request for License Amendment Regarding Minimum Critical Power Ratio Safety Limit (Proprietary)

Affidavit for Withholding Portions of Attachment A from Public Disclosure Additional Information Supporting the Request for License Amendment Regarding Minimum Critical Power Ratio Safety Limit (Non-Proprietary) cc:

Regional Administrator - NRC Region III NRC Senior Resident Inspector - Dresden Nuclear Power Station Office of Nuclear Facility Safety - Illinois Department of Nuclear Safety imlý

STATE OF ILLINOIS

)

COUNTY OF DUPAGE

)

IN THE MATTER OF

)

EXELON GENERATION COMPANY, LLC

) Docket Number DRESDEN NUCLEAR POWER STATION, UNIT 2

) 50-237

SUBJECT:

Additional Information Supporting the Request for License Amendment Regarding Minimum Critical Power Ratio Safety Limit AFFIDAVIT I affirm that the content of this transmittal is true and correct to the best of my knowledge, information and belief.

P. R. Simpson Manager - Licensing Mid-West Regional Operating Group Subscribed and sworn to before me, a Notary Public in and for the State above named, this _

T____-

day of

,_T__

H,_____No,200o'3.

OOFFIAL SE~

a tul TIOTY A. 8"YA"Mj Nýo y PubliE

Attachment B Affidavit for Withholding Portions of Attachment A from Public Disclosure

Global Nuclear Fuel A Joint Venture of GEL Toshiba. & Hitachi Affidavit I, Jens G. Andersen, state as follows:

(1) I am Fellow and project manager, TRACG Development, Global Nuclear Fuel Americas, L.L.C. ("GNF-A") and have been delegated the function of reviewing the "information described in paragraph (2) which is sought to be withheld, and have been authorized to apply for its withholding.

(2) The information sought to be withheld is contained in the attachment, "Request for Additional Information relating to Request for SLMCPR Amendment for Dresden Nuclear Power Station, Unit 2 Docket No. 50-237" March 6, 2003.

(3) In making this application for withholding of proprietary information of which it is the owner or licensee, GNF-A relies upon the exemption from disclosure set forth in the Freedom of Information Act ("FOIA"), 5 USC See. 552(b)(4), and the Trade Secrets Act, 18 USC Sec. 1905, and NRC regulations 10 CFR 9.17(a)(4) and 2.790(a)(4) for "trade secrets and commercial or financial information obtained from a person and privileged or confidential" (Exemption 4). The material for which exemption from disclosure is here sought is all "confidential commercial information," and some portions also qualify under the narrower definition of "trade secret," within the meanings assigned to those terms for purposes of FOIA Exemption 4 in, respectively, Critical Mass Energy Project v. Nuclear Regulator, Commission, 975F2d871 (DC Cir. 1992), and Public Citizen Health Research Group v. FDA, 704F2d1280 (DC Cir. 1983).

(4) Some examples of categories of information which fit into the definition of proprietary information are:

a. Information that discloses a process, method, or apparatus, including supporting data and analyses, where prevention of its use by GNF-A's competitors without license from GNF-A constitutes a competitive economic advantage over other companies;

b. Information which, if used by a competitor, would reduce his expenditure of resources or improve his competitive position in the design, manufacture, shipment, installation, assurance of quality, or licensing of a similar product;

c. Information which reveals cost or price information, production capacities, budget levels, or commercial strategies of GNF-A, its customers, or its suppliers;

d. Information which reveals aspects of past, present, or future GNF-A customer funded development plans and programs, of potential commercial value to GNF A;

e. Information which discloses patentable subject matter for which it may be desirable to obtain patent protection.

Page 1

Affidavit The information sought to be withheld is considered to be proprietary for the reasons set forth in paragraphs (4)a. and (4)b., above.

(5) The information sought to be withheld is being submitted to NRC in confidence. The information is of a sort customarily held in confidence by GNF-A, and is in fact so held.

Its initial designation as proprietary information, and the subsequent steps taken to prevent its unauthorized disclosure, are as set forth in (6) and (7) following. The information sought to be withheld has, to the best of my knowledge and belief, consistently been held in confidence by GNF-A, no public disclosure has been made, and it is not available in public sources. All disclosures to third parties including any required transmittals to NRC, have been made, or must be made, pursuant to regulatory provisions or proprietary agreements which provide for maintenance of the information in confidence.

(6) Initial approval of proprietary treatment of a document is made by the manager of the originating component, the person most likely to be acquainted with the value and sensitivity of the information in relation to industry knowledge, or subject to the terms under which it was licensed to GNF-A. Access to such documents within GNF-A is limited on a "need to know" basis.

(7) The procedure for approval of external release of such a document typically requires review by the staff manager, project manager, principal scientist or other equivalent authority, by the manager of the cognizant marketing function (or his delegate), and by the Legal Operation, for technical content, competitive effect, and determination of the accuracy of the proprietary designation. Disclosures outside GNF-A are limited to regulatory bodies, customers, and potential customers, and their agents, suppliers, and licensees, and others with a legitimate need for the information, and then only in accordance with appropriate regulatory provisions or proprietary agreements.

(8) The information identified in paragraph (2) is classified as proprietary because it contains details of GNF-A's fuel design and licensing methodology.

The development of the methods used in these analyses, along with the testing, development and approval of the supporting methodology was achieved at a significant cost, on the order of several million dollars, to GNF-A or its licensor.

(9) Public disclosure of the information sought to be withheld is likely to cause substantial harm to GNF-A's competitive position and foreclose or reduce the availability of profit making opportunities. The fuel design and licensing methodology is part of GNF-A's comprehensive BWR safety and technology base, and its commercial value extends beyond the original development cost. The value of the technology base goes beyond the extensive physical database and analytical methodology and includes development of the expertise to determine and apply the appropriate evaluation process. In addition, the technology base includes the value derived from providing analyses done with NRC approved methods.

The research, development, engineering, analytical, and NRC review costs comprise a substantial investment of time and money by GNF-A or its licensor.

C kDocuments and SettmngsNE2341 IIocal Setungs\\Temporaiy Internet Fies'\\0LK99\\gnkf&davitdJGA doc Page 2

Affidavit The precise value of the expertise to devise an evaluation process and apply the correct analytical methodology is difficult to quantify, but it clearly is substantial.

GNF-A's competitive advantage will be lost if its competitors are able to use the results of the GNF-A experience to normalize or verify their own process or if they are able to claim an equivalent understanding by demonstrating that they can arrive at the same or similar conclusions.

The value of this information to GNF-A would be lost if the information were disclosed to the public. Making such information available to competitors without their having been required to undertake a similar expenditure of resources would unfairly provide competitors with a windfall, and deprive GNF-A of the opportunity to exercise its competitive advantage to seek an adequate return on its large investment in developing and obtaining these very valuable analytical tools.

I declare under penalty of perjury that the foregoing affidavit and the matters stated therein are true and correct to the best of my knowledge, information, and belief.

Executed at Wilmington, North Carolina, this 6th day of March 2003.

Jens G. Andersen Global Nuclear Fuel - Americas, LLC C \\Documents and SetnngsNE2341 MLocal Settngs\\Temporary Internet Fi es\\OLK99VMgnfa.affidavitJGA-doc Page 3

Attachment C Additional Information Supporting the Request for License Amendment Regarding Minimum Critical Power Ratio Safety Limit (Non-Proprietary)

March 6, 2003 REQUEST FOR ADDITIONAL INFORMATION RELATING TO REQUEST FOR SLMCPR AMENDMENT FOR DRESDEN NUCLEAR POWER STATION, UNIT 2 DOCKET NO. 50-237 The staff has reviewed the January 31, 2003 submittal regarding changes to the Dresden Unit 2 Cycle 18 Safety Limit Minimum Critical Power Ratio (SLMCPR) and has identified the need for the following additional information from the licensee.

1. Describe any applicable procedures used to verify that the results of analysis for the SLMCPR is normal for the cycle-specific operation and describe the process by which the non-conservative SLMCPR values were discovered. Also, provide the root cause of the error and corrective actions, and describe any impact due to this error on the operation related to a mixed core operation.

Response

Process and Procedures The SLMCPR evaluations are performed in accordance with GNF's technical design procedure

((

1

)). This TDP is accompanied by GNF's analysis guide ((

)) which specifies items that are checked as part of the verification. The NRC approved methodology employs a Monte Carlo calculation. ((

((GNF Proprietary Information))

page 1 of 10

((removed between double brackets))

March 6, 2003 The calculated SLMCPR values ((

)) were compared as part of the original SLMCPR evaluation for Dresden 2, Cycle 18 completed in May 2001 and summarized in Reference 2. There was some indication at that time that the scatter between results beginning with the peak hot exposure (PHE) evaluation point at a cycle exposure of 12.0 GWd/MTU and continuing to the end of cycle (EOC) was somewhat larger than is typically seen. These discrepancies appeared to be justified in light of the substantial uncertainties associated with these calculational methods. The ability to discern the significance of these discrepancies was obscured by a number of circumstances.

(1) The power distribution uncertainties stipulated for Dresden 2, Cycle 18 were even larger than given in GETAB. ((

)) this appeared to be part of the explanation for while the scatter was somewhat larger than typical. Some of the non-power uncertainties stipulated for Dresden 2, Cycle 18 were also higher than stipulated for GETAB which further exaggerated (to a lesser extent) the scatter in the calculated values.

(2) A very conservative value for the critical power correlation was being used for the ATRIUM-9B fuel. It is typical that the contribution to the SLMCPR for once-burned

((GNF Proprietary Information))

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((enclosed by double brackets ))

March 6, 2003 fuel is greatest at the beginning of the new cycle. The fact that the highest calculated SLMCPR was occurring at a cycle exposure of 6.0 GWd/MTU was consistently predicted ((

)) and was consistent with expectations based on GNF previous experience with similar mixed-core analyses. Larger differences in the SLMCPR comparisons later in the cycle were accepted since even the largest of the calculated values were being bounded by the Monte Carlo value calculated at a middle of cycle (MOC) 6 analysis point at a cycle exposure of 6.0 GWd/MTU.

(3) Trends in the SLMCPR versus exposure depend on the bundle design, core loading and how the core is operated. It is often helpful to compare the SLMCPR calculations for two cycles when the core and bundle designs are similar and the operation strategy is similar. Such comparisons of Dresden 2, Cycle 18 to Cycle 17 were not possible because: (a) the Cycle 17 SLMCPR evaluation was performed using a different proprietary method((

I].

(4) For the Cycle 18 calculations, ((

)) methods indicated similar trends in the calculated SLMCPR values starting from BOC, continuing past the limiting exposure point at 6.0 GWd/MTU up to and including the evaluation point at 9.0 GWd/MTU. This supported the conclusion that use of a Tech Spec SLMCPR value of 1.08 based on a rounding up of the limiting Monte Carlo calculated SLMCPR value of 1.0741 was appropriate.

Calculational Trail Leading to Discovery of the Error As noted in Reference 3, the need to evaluate ((

)) surfaced in February 2002 about nine months after the original calculations were completed in May 2001 for Dresden 2, Cycle 18. GNF completed an assessment ((

)) March 7, 2002. As a result the SLMCPR at EOC for Dresden 2, Cycle 18 increased by 0.02240 from 1.06810 to 1.0905 and became the highest value for the cycle. This assessment is documented together with the original calculations ((

In September 2002, another GNF engineer performed additional SLMCPR calculations for the Dresden 2, Cycle 18 core applying the revised methodology ((

(( GNF Proprietary Information ))

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(( removed between double brackets))

March 6, 2003

)) The preliminary results indicated that the calculated SLMCPR increased from the original value of 1.068 to 1.114 at the EOC calculation point. An increase of 0.0224 ((

)) was expected based on the results from the March 7, 2002 assessment.

)) Instead of an expected net increase of approximately 0.0124, the calculations showed a total increase of 0.046. Approximately 0.034 of this increase was not expected and could not be explained ((

)) GNF incorrectly concluded that the current results were erroneous, whereas, in hindsight it is known that the problem was in the original verified calculations and not with the more recent results.

In December 2002 GNF was asked to support the submittal of a letter to the NRC requesting a change in the Technical Specification SLMCPR value for Dresden 2, Cycle 18. ((

)) The expectation based on prior experience was that the calculated SLMCPR values would be within the calculational uncertainty of the original values. This was not the case. This motivated the engineer to examine his most recent results and compare them to the original calculations to try and determine the source of the differences. It was then that the problem with the TIP input for the original calculations was discovered. The engineer notified management of the error and then proceeded to repeat the original calculations from the reference loading pattern using the corrected TIP inputs. The new results were essentially identical with the exposure accounting results as was anticipated. ((

Root Cause The following is a summary of the details contained in corrective action request ((

)) The root cause is that an input error was made in defining the TIP inputs required as part of the SLMCPR calculation. ((

(( GNF Proprietary Information))

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(( enclosed by double brackets ))

March 6, 2003

)) Once initially entered, the TIP array is propagated. ((

Procedural and Human Factors

)) It is postulated that both the performer and the verifier failed to carefully check the TIP inputs out of habit of knowing that the data propagates correctly once it has been correctly entered. Normally there is not a problem in the TIP inputs because once correctly entered, the array is propagated to other derived cases. For most plants this information is carried forward from one cycle to the next since it does not change; however, for Dresden 2, Cycle 18 this was not the case because GNF had not simulated nor monitored the Dresden 2 plant in many years. ((

1]

Dresden 2 does not use a GNF core monitoring system.

The DVG check question is considered to be a contributing factor because it does not precisely focus on the need to specify full-core inputs regardless of the symmetry option being used in PANACEA.

Effects and Extents Prior to the discovery of the error, the Technical Specification SLMCPR value for Dresden 2, Cycle 18 was 1.08. Dresden 2, Cycle 18 could have operated with a Technical Specification SLMCPR value that was non-conservative by 0.01 in the cycle exposure range from 3 to 9 GWd/MT. During this period of operation the maximum MCPR ratio to limits was 0.90 or less, so a higher required SLMCPR of 1.09 would not have been violated even if there had been a design basis anticipated operational occurrence. If operation had continued to EOC the Technical Specification SLMCPR at EOC would have been non-conservative by as much as 0.03.

The TIP inputs for all other current operating cycles for all plants for which GNF has performed SLMCPR evaluations have been checked. The problem existed only for Dresden 2, Cycle 18.

(( GNF Proprietary Information ))

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March 6, 2003 Corrective and Preventive Actions The following two GNF corrective actions had been identified:

1. Evaluate PRC 03-01 and determine if this is a reportable condition. Included in this evaluation is confirmation that no other plants are affected.

2. Recalculate the SLMCPR values for Dresden 2, Cycle 18 and submit to licensee.

Both corrective actions have been completed. The error has been determined by GNF to be reportable under 10CFR Part 21. Only Dresden 2, Cycle 18 was affected by the error. The SLMCPR values for Dresden 2, Cycle 18 have been recalculated and are presented in Tables 1 and 2 of this document as part of the response to the second NRC request.

The following three GNF preventive actions have been identified:

1. Perform sensitivity training on this specific issue. Training must cover sensitivity to attention to detail and caution against pre-conditioned responses due to familiarity with tasks. Sensitivity training was completed February 17, 2003.

2. ((

)) Specifically add a checklist item to the design verification guide to confirm that ((

)) TIP configuration values have been correctly used in the SLMCPR evaluation.

3. ((

Preventive actions 2 and 3 are being coordinated by GNF to provide the maximum protection against reoccurrences of this error.

Specific Impacts Related to Mixed Core Operation A general statement about how the error will impact the calculated SLMCPR for a mixed core cannot be made nor can such a statement be made for any other core configuration. Even equilibrium cores are a mixture of fuel bundles at different exposures. The GNF SLMCPR methodology evaluates the unique core loading for each cycle. ((

)) Other considerations such as an increased uncertainty for a particular fuel type are explicitly considered. For a non-GNF fuel design a higher uncertainty may be required which will cause a slightly greater scatter in the MCPR values from one Monte Carlo trial to the next.

When it is necessary to deviate from familiar processes in order to accommodate a change from one vendor's fuel to another, the risk of an error increases. This increased risk is compounded by the fact that a lower level of experience with treating these less familiar calculations will increase the likelihood that an error will not be readily detected. These considerations have already been discussed at length in the paragraphs above. It is clear that there were specific factors related to the Dresden 2, Cycle 18 SLMCPR evaluation that contributed to the error and resulted in the failure to detect the error earlier.

((GNF Proprietary Information))

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I

March 6, 2003

2. Please revisit the response dated September 17, 2001 (RS-01-193) and identify the difference for D2C18 operation at that time for requesting a large reduction of SLMCPR values and at the present time for requesting a large increase of SLMCPR values.

Provide a Table to show net adjustment to SLMCPR for both dual loop operation and single loop operation including BOC, MOC, and EOC. Please identify the major contributor to the large change of the SLMCPR value (i.e., from 0.03 to 0.05). Clarify which fuel assembly in the Cycle 18 core (ATRIUM-9B or GEl4) is dominant during the entire Cycle 18 operation and justify that the proposed straight SLMCPR values instead of the cycle exposure dependent SLMCPR values for two recirculation loop and single loop operation bound the Cycle 18 operation. Clarify that total uncertainty in the GEXL96 correlation predictions for ATRIUM-9B fuel in the response to the staff RAI (RS-01-193) is still valid.

Response

The attachment to Reference 4 (RS-01-193) contained three questions along with their responses.

The question and response for question 3 require no changes. Some additional clarification is needed in the response to question 1. First, let us indicate what has not changed. The core loading that is addressed in question 1 has not changed. The CPR correlation uncertainty of

((

)) as applied to the ATRIUM 9B fuel has not changed and is still valid.

Clarification is warranted in the Reference 4 response regarding the ((

)) uncertainty that is quoted for the GEXL14 correlation. As noted in Reference 5, GNF has been using updated values ((

)) since March 2002 in accordance with Reference 3.

The question stated above encompasses all the relevant elements from question 2 in the attachment to Reference 4. It is clear that the response to question 2 in Reference 4 should be discarded since it refers to the erroneous original SLMCPR calculations completed by GNF in May 2001. The remainder of this response is directed to answering the question stated above.

The calculated SLMCPR values for dual loop operation (DLO) are shown in Table 1. Two sets of results are shown. The results in the left half of the Table 1 are the erroneous results calculated by GNF in May 2001 while the right half of table contains the current calculated values. The erroneous results in the left half of Table 1 were the bases for originally requesting a reduction in the SLMCPR value in the Technical Specifications for Dresden 2, Cycle 18 in September 2001. The corrected results in the right half of Table 1 show that an even higher SLMCPR value is needed for Dresden 2, Cycle 18 than was used for Cycle 17. ((

)) Shading and bold text is used to emphasize the values calculated using the NRC approved Monte Carlo process. ((

((GNF Proprietary Information))

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March 6, 2003 The rightmost column of Table 1 reveals that the magnitude of the error in the Monte Carlo results increased slowly with exposure and remained approximately 0.019 at the limiting points in the cycle. ((

)) The combined impact of these two effects is what causes the SLMCPR to increase by a total amount of 0.041 from the original 1.068 value at EOC. Thus the corrected calculation at EOC becomes nominally 1.11 and establishes the highest SLMCPR value for the cycle when in dual loop operations.

The calculated SLMCPR values for single loop operation (SLO) have been separately presented in Table 2. Like Table 1, Table 2 includes two sets of results. The results in the left half of the Table 2 are the erroneous results calculated by GNF in May 2001 while the right half of table contains the current calculated values. ((

The erroneous SLO results calculated in May 2001 suggested that the limiting point occurred at a cycle exposure of 6 GWd/MTU. ((

)) accurately predicted that the limiting SLMCPR for SLO should nominally be 1.12 and should occur at EOC. This SLO value was confirmed by the corrected Monte Carlo calculations completed in December 2002.

The percentage participation of the ATRIUM-9B and GEl4 fuel in terms of their contribution to the total number of rods susceptible to boiling transition are shown in Table 3 as a function of the cycle exposure. Both the erroneous and the corrected results are shown. The trends versus exposure are similar with and without the error; however, the GEl4 participations are slightly higher after the error was corrected for all but the BOC point.

((GNF Proprietary Information))

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((enclosed by double brackets ))

March 6, 2003 Table 1: Calculated SLMCPR Values for Dual Loop Operations Erroneous Calculations Corrected Calculations Error Cycle

((

[

Impact Exposure Monte Monte Monte (GWdJMTU)

Carlo

((

j]

Carlo J[j]

j]

Carlo 0

1.035

((J]

((L

))

1.046

((

1] if

]L 0.011 3

1.043

((

]

((

1.057 iLJf

]

0.014 6

1.074

((J]

((11]

1.092 f

))((

))

0.018 9

1.041

((

))

f[

1]

1.059

[1L ]

]

0.018 12 1.057 1L

]

]1[

1.077

((

1

((

))

0.020 15 r

j 1i090a n/a n/a 1.1 0 9b",

1.121 1.100 0.019 Ii.

Notes: a Estimated 3/7/02 ((

b Based on actual calculation ((

Table 2: Calculated SLMCPR Values for Single Loop Operations (SLO)

Cycle Erroneous Corrected Exposure Monte Monte (GWd/MTU)

Carlo

[LJ]

Carlo

[

11 0

1.044

((I1]

3 1.065 j[j))

6 1.088

((

]

1.104 I((

))

9 1.069

[L

))

12 1.084 j))

15 otes:

1. 120't if 11 3

2 1 20 b Notes: a Estimated 3/7/02 [

b Based on actual calculation ((

Table 3: Participation Percentages during Cycle Cycle Erroneous Corrected Exposure (GWd/MTU)

ATRIUM-9B GE14 ATRIUM-9B GE14 0

86.9 13.1 89.5 10 5 3

73.1 26.9 69.9 30.1 6

47.8 52.2 46.2 53.8 9

12.1 87.9 9.1 90.9 12 7.7 92.3 5.8 94.2 15 iff 15 1.7-98.3-1.5 98.5 a Estimated.

(( GNF Proprietary Information ))

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(( removed between double brackets))

1]

]I.fl R]

March 6, 2003 References for Responses 1 and 2

[1] Letter, G.A. Watford (GNF) to NRC Document Control Desk with attention to S. Dembeck and T. Huang; "Supplementary Information Concerning Safety Limit MCPR", GAW-99-007, August 17, 1999.

[2] Letter from R. M. Krich (Exelon Generation Company, LLC) to U. S. NRC, "Request for Technical Specifications Change for Minimum Critical Power Ratio Safety Limit," dated June 6, 2001. See attachment: "Additional Information Regarding the Cycle Specific SLMCPR for Dresden Unit 2 Cycle 18", June 4, 2001.

[3] Letter, Glen A. Watford (GNF-A) to U. S. Nuclear Regulatory Commission Document Control Desk with attention to J. Donoghue (NRC), "Final Presentation Material for GEXL Presentation - February 11, 2002", FLN-2002-004, February 12, 2002.

[4] Letter from T. W. Simpkin (Exelon Generation Company, LLC) to U. S. NRC, "Additional Information Supporting the Request for Technical Specifications Change for Minimum Critical Power Ratio Safety Limit", RS-01-193, dated September 17, 2001.

[5] Letter from P. R. Simpson (Exelon Generation Company, LLC) to U. S. NRC, "Request for License Amendment Regarding Minimum Critical Power Ratio Safety Limit", RS-03-023, dated January 31, 2003. See attachment: "Additional Information Regarding the Cycle Specific SLMCPR for Dresden Unit 2 Cycle 18", January 14, 2003.

((GNF Proprietary Information))

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