ML033450393
| ML033450393 | |
| Person / Time | |
|---|---|
| Site: | Catawba  |
| Issue date: | 12/11/2003 |
| From: | Martin R NRC/NRR/DLPM/LPD2 |
| To: | Tuckman M Duke Energy Corp |
| References | |
| TAC MB7863, TAC MB7864 | |
| Download: ML033450393 (8) | |
Text
Robert Martin - Draft RAI on MOX Pg From:
Robert Martin To:
InTERNET: gacopp@duke-energy.com Date:
12/11/03 9:03AM
Subject:
Draft RAI on MOX In accordance with the procedures in LIC-101, License Amendment Review Procedures" we propose to discuss the draft Request for Additional Information with you and your staff prior to issuing it formally.
Would you and your staff be available today at 2:00 pm for such a call on the radiological consequences portion of the RAI?
CC:
LaVie, Steve
NUCLEAR UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 Mr. Michael S. Tuckman Executive Vice President Duke Energy Corporation 526 South Church St Charlotte, NC 28201-1006
SUBJECT:
CATAWBA NUCLEAR STATION, UNITS 1 AND 2 - REQUEST FOR ADDITIONAL INFORMATION RE: MIXED OXIDE LEAD FUEL ASSEMBLIES (TAC NOS. MB7863 AND MB7864)
Dear Mr. Tuckman:
By letter dated February 27, 2003, you submitted an application for amendments to the operating licenses for Catawba Nuclear Station, Units 1 and 2. The proposed amendments would revise the Technical Specifications to allow the use of four mixed oxide fuel assemblies at the Catawba station. The Nuclear Regulatory Commission staff has reviewed the information provided and has determined that additional information is required as identified in the Enclosure.
We discussed these questions with your staff on December xx, 2003. Your staff indicated that a response to these issues could be provided within thirty (30) days. Please contact me at (301) 415-1493, if you have any other questions on these issues.
Sincerely, Robert E. Martin, Senior Project Manager, Section 1 Project Directorate II Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket Nos. 50-413 and 50-414
Enclosure:
Request for Additional Information cc w/enc See next page
REQUEST FOR ADDITIONAL INFORMATION ON APPLICATION FOR MOX LEAD TEST ASSEMBLIES DUKE POWER COMPANY CATAWBA NUCLEAR STATION. UNITS 1 AND 2 DOCKET NOS. 50-413 AND 50-414 Materials Engineering Section 3.6.1 of Attachment 3 to the Duke Power (licensee or Duke) letter dated February 27, 2003, indicates that the fast flux impacting the reactor vessel will be virtually identical to that for a reactor core consisting entirely of low enriched uranium (LEU) fuel. The licensee states that the Reactor Vessel Integrity Program will manage the reduction in fracture toughness of the reactor vessel beltline region so that the function of the vessel is maintained. The licensee states that the existing pressure-temperature curves in the Catawba Technical Specifications will remain valid with the use of four mixed oxide (MOX) lead test assemblies.
The Nuclear Regulatory Commission (NRC) staff requests that the licensee identify the capsules, dosimetry, capsule withdrawal schedule, and projected neutron fluence for the capsules that will be in the vessel during the period of time that the MOX fuel will be utilized.
The test results from the reactor vessel material samples should be compared to the results predicted using Regulatory Guide (RG) 1.99, Revision 2, Radiation Embrittlement of Reactor Vessel Materials," and dosimetry should be evaluated in accordance with RG 1.190, "Calculational and Dosimetry Methods for Determining Pressure Vessel Neutron Fluence.'
Provide a basis for concluding that there is no change required in the withdrawal schedule for the capsules in the vessel during the period of time that MOX fuel will be utilized.
Radiological Consequences By letter dated February 27, 2003, Duke requested a license amendment related to the use of four MOX lead test assemblies. The staff requested additional information (RAI) by letter dated July 25, 2003 and Duke responded to that RAI on November 3, 2003. In reviewing the responses to the radiological consequences questions, the NRC staff has identified some areas where additional clarification or information is required to enable the staff to make its requisite safety findings.
- 1.
With regard to Footnote 3 to Table Q12-3 (cited in the response to RAI Question 3),
Section 4.5 of Regulatory Guide 1.195, "Methods and Assumptions for Evaluating Radiological Consequences of Design Basis Accidents at Light-Water Nuclear Power Plants," does state that 50 rem thyroid may be used as the acceptance criterion.
However, Section B of the guide states: "The guidance contained in this regulatory guide will supersede corresponding radiological analysis assumptions provided in other regulatory guides when used in coniunction with guidance that is in RegulatorY Guide 1.196, 'Control Room Habitability at Light-Water Nuclear Power Reactors."' Please provide a commitment to the guidance of Regulatory Guide 1.196, identifying proposed alternatives to the guidance, if any, that are proposed by Duke.
- 2.
Table Q3(a)-1 states that the control room X/Q value from Reference Q3(a)- is "increased' to a value of 1.04E-3 seconds/cubic meters (sec/M 3) for unit vent releases.
The citation to Reference Q3(a)-i appears to be in error. The NRC staff believes that the most recently approved value for this parameter is 1.74E-3 sec/m3 (See Catawba Amendments 198 and 191 dated April 23, 2002). Please resolve this apparent difference in values. If the 1.04E-3 seciM3 value is a newly calculated value, please provide a revised response to RAI Question 3.c.
- 3.
In response to RAI Question 3.b on Page 93, Duke indicates that a LOCA is the most restrictive accident and its thyroid dose is more restrictive than its whole body dose.
Please explain whether control room dose was considered in this conclusion and, if not, how this omission would impact this conclusion.
- 4.
A sentence in the last paragraph on page 94 states that: Included in these tables is an evaluation of the results for the Catawba AST LOCA including MOX lead assemblies."
That sentence could imply that the staff is currently reviewing an analysis of a LOCA with AST and MOX lead assemblies for Catawba. This would be in error since Duke did not address MOX fuel in the AST amendment currently under review. Please clarify.
- 5.
The NRC staff finds the response to RAI Question 3.g. to be inadequate. This question asked for a justification for the continued use of the gap fractions in Table 3 of Regulatory Guide 1.183, "Alternative Radiological Source Terms For Evaluating Design Basis accidents At Nuclear Power Reactors." Duke responded to the staff's question by proposing to increase the Table 3 values (except alkali metals) by a multiplier of 1.5 without an adequate explanation of why the Table 3 values, adjusted by the multiplier, would reasonably bound the expected gap fractions for weapons-grade MOX assemblies with burnups to 60 Gigawatt days/Metric ton heavy metal (GWd/MThm).
Duke is requested to provide the staff with a basis for concluding that this multiplier is acceptable for all isotopic groups, including alkali metal, for weapons-grade MOX.
The NRC staff believes that the discussion provided in the response could be considered to provide qualitative support for Duke's conclusions regarding LOCA release fractions for the gap phase, but it does not establish the adequacy of the gap fraction multiplier for use with Table 3 for non-LOCA events. The expert panel identified in Duke's response was impaneled by the NRC in 2001 to address (1) whether or not the data in NUREG-1465, "Accident Source Terms for Light-Water Nuclear Power Plants," would apply to high burnup LEU fuel; (2) and to reactors using mixed oxide fuel. The panel reviewed available data and made recommendations for changes to the NUREG-1465 release phase fractions. Duke attempted to use the insights of the expert panel to address the adequacy of the Table 3 values as stated in the following paragraph from page 106 of Duke's November 3, 2003 response:
Since [Regulatory Guide 1.183] Table 3 is based upon expert panel work which was published in [NUREG-1465] and the panel saw similarities in gap release rates between LEU and MOX fuel, it could be inferred that the gap release rates in [Regulatory Guide 1.183] Table 3 should also be valid for MOX fuel gap releases.
However, (1) the data in Table 3 were not derived from NUREG-1465. These data were generated by the NRC staff in recognition of the fact that the core average gap release fractions in NUREG-1 465 were inappropriate for use with non-LOCA events since the gap fraction of many assemblies in the core could exceed the core average value.
(2) The expert panel's deliberations were limited to LOCAs and other severe accidents involving a substantial portion of the core, since this was the direction given to the panel.
(3) Section 3.4.2 of the panel report tabulated the MOX fuel characteristics considered by the panel. This included a maximum burnup on an assembly basis of approximately 46 Gigawatt days/ton (GWd/t). Duke has requested MOX LTA burnups to 60 GWd/t.
(4) The panel's conclusions are not directly applicable to a comparison of an LEU assembly and a MOX assembly since the panel considered core-average releases from the LEU core and core-average releases from the core containing 40% MOX assemblies.
- 6.
In the response to Question 3.g, Duke provided a graph of fission gas data for European reactor-grade MOX fuel and LEU fuel. With regard to this graph, please provide the following information:
a An explanation of the data sets represented on this graph. For example, what fuel configurations are included, what plutonium concentrations, what LEU enrichments, PWR / BWR / MAGNOX / etc. How were the data obtained?
- b.
Was the linear heat generation rate (LHGR) for these assemblies comparable to what Duke proposes for the MOX LTAs?
- c.
How do the data showing a nearly vertical rise in the MOX fission gas release (FGR) that occurs about 43,000 MWd/MThm support Duke's planned burnup to 60,000 MWd/MThm?
- d.
Taking the four highest MOX data points at about 43,000 MWd/MThm, the MOX FGR values range from 4.5 to 7, implying an uncertainty of nearly 50% at this burnup. How is this uncertainty addressed?
- 7.
In the response to RAI Question 3.1, Duke stated: "...a corresponding elemental
[decontamination factor] DF of 350 is derived for use in the fuel handling accident (FHA) and weir gate drop (WGD) analyses." But, later in the response, it is stated that a DF of 200 is used. Please confirm that a DF of 200 is the licensing basis value and not 350.
- 8.
In the response to RAI Question 3.j, Duke stated that the MOX fuel and AST amendments are two separate issues. However, the NRC staff notes that the guidance in RG 1.183 that allows licensees to not redo all of the radiological analyses at the time of an AST amendment request was predicated on a staff analysis that concluded that the whole body and thyroid doses methods and the traditional TID14844 source term would generally result in a dose result that was more restrictive than the corresponding AST and TEDE analysis, assuming that all other parameters were held constant.
However, since TID 14844 is based on the use of LEU fuel, this staff analysis did not encompass the use of MOX LTAs. Given the potentially higher fission product inventory and gap fractions associated with MOX fuel, this assumption as incorporated into Regulatory Guide 1.183 may not be valid for MOX fuel. Since both amendment requests have been submitted for NRC staff review, the relationship between the two amendments needs to be clarified in this regard.
The staff's concern is related to maintaining the consistency between the design basis analyses and the licensing bases, given two sets of analyses. For example, some of the analyses supporting the MOX LTAs are evaluated using whole body and thyroid dose acceptance criteria. Yet, if the AST amendment were to be approved, the licensing basis for Catawba would then be based on AST and TEDE, since Duke requested a full implementation of the AST. The NRC staff observes that If either the locked rotor or rod ejection analyses needed to be redone for any reason during the two cycle irradiation of
the LTAs, Duke would be expected to update the analyses to be consistent with the licensing basis (Section 1.3.4 of Regulatory Guide 1.183). However, the gap fractions approved for the MOX LTAs are not those approved under the AST amendment. A re-submittal under 10 CFR 50.67 may be necessary since changing the gap fraction would constitute a change to the source term.
Please explain how Duke intends to ensure that the design basis remains consistent with the licensing basis given the relationship between the two sets of analyses.
Catawba Nuclear Station cc:
Mr. Larry Rudy, Acting Regulatory Compliance Manager Duke Energy Corporation 4800 Concord Road York, South Carolina 29745 Ms. Lisa F. Vaughn Duke Energy Corporation Mail Code - PB05E 422 South Church Street P.O. Box 1244 Charlotte, North Carolina 28201 -1244 Anne Cottingham, Esquire Winston and Strawn 1400 L Street, NW Washington, DC 20005 North Carolina Municipal Power Agency Number 1 1427 Meadowwood Boulevard P. O. Box 29513 Raleigh, North Carolina 27626 County Manager of York County York County Courthouse York, South Carolina 29745 Piedmont Municipal Power Agency 121 Village Drive Greer, South Carolina 29651 Ms. Karen E. Long Assistant Attorney General North Carolina Department of Justice P. 0. Box 629 Raleigh, North Carolina 27602 North Carolina Electric Membership Corporation P. 0. Box 27306 Raleigh, North Carolina 27611 Senior Resident Inspector U.S. Nuclear Regulatory Commission 4830 Concord Road York, South Carolina 29745 Henry Porter, Assistant Director Division of Waste Management Bureau of Land and Waste Management Department of Health and Environmental Control 2600 Bull Street Columbia, South Carolina 29201-1708 Mr. Michael T. Cash Manager - Nuclear Regulatory Licensing Duke Energy Corporation 526 South Church Street Charlotte, North Carolina 28201-1006 Saluda River Electric P. 0. Box 929 Laurens, South Carolina 29360 Mr. Peter R. Harden, IV VP-Customer Relations and Sales Westinghouse Electric Company 6000 Fairview Road 12th Floor Charlotte, North Carolina 28210 NCEM REP Program Manager 4713 Mail Service Center Raleigh, NC 27699-4713
Catawba Nuclear Station cc:
Mr. T. Richard Puryear Owners Group (NCEMC)
Duke Energy Corporation 4800 Concord Road York, South Carolina 29745 Richard M. Fry, Director Division of Radiation Protection North Carolina Department of Environment, Health, and Natural Resources 3825 Barrett Drive Raleigh, North Carolina 27609-7721