ML041680518

Blue Ridge Environmental Defense League'S Response to Duke Energy Corporation'S Second Set of Interrogatories and Requests for Production of Documents

ML041680518
Person / Time
Site:	Catawba
Issue date:	06/08/2004
From:	Curran D, Edwin Lyman Blue Ridge Environmental Defense League, Harmon, Curran, Harmon, Curran, Spielberg & Eisenberg, LLP
To:	Atomic Safety and Licensing Board Panel
Byrdsong A T
References
50-413-OLA, 50-414-OLA, ASLBP 03-815-03-OLA, RAS 7942
Download: ML041680518 (20)

Text

RAcs LATED WORRESPONDEha, June 8, 2004 DOCKETED UNITED STATES OF AME zRICA USNRC NUCLEAR REGULATORY CONAMISSION June 15, 2004 (10:08AM)

BEFORE THE ATOMIC SAFETY AND L ICENSING BOARD OFFICE OF SECRETARY RULEMAKINGS AND In the Matter of: ADJUDICATIONS STAFF

)

) Docket Nos. 50-413-OLA DUKE ENERGY CORPORATION ) 50-414-OLA

)

(Catawba Nuclear Station, )

Units 1 and 2) )

BLUE RIDGE ENVIRONMENTAL DEFENSE LEAGUE'S RESPONSE TO DUKE ENERGY CORPORATION'S SECOND SET OF INTERROGATORIES AND REQUESTS FOR PRODUCTION OF DOCUMENTS In accordance with the schedule established in the Atomic Safety and Licensing Board's

("ASLB's") May 25, 2004, Order (Regarding Proposed Redacted Memorandum & Order, and Proposed Schedule Changes), Blue Ridge Environmental Defense League ("BREDL") hereby responds to Duke Energy Corporation's Second Set of Interrogatories and Requests for Production of Documents Directed to Blue Ridge Environmental Defense League (April 26, 2004).

II. GENERAL Interrogatory31 Identify each person who supplied information for responding to these interrogatories and requests for the production of documents. Note the specific interrogatories for which each such person supplied information.

RESPONSE: Answers to these interrogatories and requests for the production of documents were provided by Dr. Edwin S. Lyman.

III. BREDL CONTENTION I Interrogatory32 In the April 14, 2004 response to Duke's First Set of Interrogatories, Interrogatory 4, BREDL listed a number of specific MOX fuel behaviors that BREDL ip plate=sacy- 035 -eci o;

asserts will affect a LOCA scenario. For each of the following, provide the requested additional information:

a. Rod centerline temperature as a function of power: Duke has stated that Framatome ANP performed the MOX fuel LOCA analyses1 using MOX fuel specific fuel temperatures and properties based on the COPERNIC code. Given this fact, is it BREDL's position that the MOX fuel-specific rod centerline temperature is not modeled properly in the MOX fuel design basis LOCA event analyses? If not, explain why not.

I Letter, M. S. Tuckman (Duke) to U. S. Nuclear Regulatory Commission, Proposed Amendments to McGuire and Catawba Facility Operating Licenses to Allow Insertion of Mixed Oxide Fuel Lead Assemblies, February 27, 2003.

RESPONSE: BREDL does not assert that the MOX fuel-specific rod centerline temperature is not modeled properly in the MOX fuel design-basis LOCA analyses. Rather, BREDL asserts that because the MOX centerline temperature is typically higher than the LEU centerline temperature for the same rod power, the margin to the design-basis LOCA temperature limit is in general smaller for MOX fuel assemblies than for LEU fuel assemblies at the same linear power density.

b. Fuel-clad interaction: What specific type of fuel-clad interactions does BREDL assert will affect a LOCA? Classify each different interaction as a mechanical, nuclear, or chemical interaction. Describe any basis that BREDL has that MOX fuel will interact with cladding in a manner that is different from LEU fuel. If there is an asserted difference in quantitative terms, how would this difference have an adverse impact on the response to a design basis LOCA event?

RESPONSE: In referring to fuel-clad interaction, BREDL refers generally to both mechanical and chemical interactions, which are closely coupled in high-burnup fuel. According to the Nuclear Energy Agency, formation of a chemical bonding layer between fuel and clad "induces a severe pellet-clad mechanical interaction." Nuclear Energy Agency, NuclearFuel Safety CriteriaTechnical Review, Organization for Economic Co-operation and Development (OECD) at 23 (2001). BREDL is concerned specifically with the impact of fuel-clad bonding on fuel 2

relocation behavior during a design-basis LOCA. During NRC's recent expert elicitation (PIRT) process on LOCA issues for high-burmup fuel, all four participating experts agreed that "chemical and mechanical bonding between the fuel pellet and the cladding ... " was of high importance to the fuel relocation phenomenon, because "bonding could significantly affect the relocation characteristics by impeding pellet fragment movement." NUREG/CR-6744, "Phenomenon Identification and Ranking Tables (PIRT) for Loss-of-Coolant Accidents in Pressurized and Boiling Water Reactors Containing High-Burnup Fuel," Appendix D, Table D-1 at D-69 (December 2001).

With regard to differences in fuel-clad bonding behavior between LEU and MOX fuels, BREDL again notes NRC's statement that "chemical bonding between the pellets and the cladding, which may be different for MOX pellets and U0 2 pellets, may affect the ballooning process and hence the clad behavior." "Agency Plan for Confirmatory Research Associated With the Use of Mixed-Oxide Fuel in Commercial Light-Water Reactors," Attachment at 2 (February 11, 2000).

According to IPSN (now IRSN), tight fuel-clad bonding may delay the onset of fuel relocation. A. Mailliat and M. Schwartz, IPSN, "Need for Experimental Programmes on LOCA Issues Using High-Burnup and MOX Fuels," NUREG/CP-0176, Proceedingsof the NRC Nuclear Safety Research Conference at 433 (March 2002). Tight bonding has also been observed at the Halden reactor in Norway to retard the rate of balloon formation. Nuclear Energy Agency, NEA/CSNI/R(2003)9, Ongoing and PlannedFuel Safety Research in NEA Member States at 79 (March 5, 2003). It has been confirmed that MOX fuel is more resistant to clad failures due to pellet-clad mechanical interaction (PCMI) than LEU fuel, even at high burnups. Nuclear Energy Agency, NEA/NSC/DOC(2004)8, InternationalSeminar on Pellet-CladInteractions with Water 3.

ReactorFuels, at 20 (May 6, 2004). This phenomenon is not well-understood but may imply that the pellet-clad bond is weaker for MOX fuel, in which case MOX fuel may have a greater propensity to earlier and more extensive fuel relocation than LEU.

In Duke's April 14, 2004, Response to BREDL's first set of discovery requests, Duke stated that the Framatome design-basis LOCA analysis for the MOX LTAs did not assume any fuel-clad bonding and was therefore "conservative" with respect to the requirement that the degree of cladding swelling not be underestimated. Id. at 14. However, in the absence of an assessment of whether and to what extent the pellet-clad interaction is weaker in MOX fuel than in LEU fuel, there is no way of knowing the degree to which this assumption is conservative for MOX fuel. Therefore, Duke's failure to properly account for this phenomenon contributes another uncertainty to the safety margin associated with Duke's design basis LOCA calculation.

Moreover, there is evidence to contradict Duke's assertion that "deterministic LOCA evaluations typically based on data taken from unirradiated cladding" are conservative with respect to clad swelling. According to IPSN (now IRSN), results from the PBF-LOC experiments found that irradiated rods experienced greater clad deformation than unirradiated rods during design-basis LOCA conditions. See Mailliat and Schwartz at 432 (2002), op cit. There is simply no way to determine whether Duke's design-basis LOCA analysis underestimates or overestimates the degree of clad swelling (and hence the degree of fuel relocation) for MOX LTAs without additional experimental data from integral LOCA tests of high-burnup MOX fuel rods. Given the lack of data, BREDL finds unpersuasive the NRC's 1999 speculation, quoted by Duke in its April 14, 2004 set of responses to BREDL's discovery requests, that "a major effect is not expected" with regard to differences in pellet-clad bonding between MOX and LEU. Id. at 15.

c. Peak clad temperature ("PCT"): Explain how PCT is a specific MOX fuel behavior that will affect a design basis LOCA event.

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RESPONSE: As Duke's calculations have themselves demonstrated, the peak clad temperature (PCT) in a design-basis LOCA is higher for a MOX rod than for an LEU rod in the same position in the core. Duke MOX LTA LAR at 3-43 (February 27, 2003). The margin to the 10 CFR § 50.46 PCT limit of 22000F is therefore smaller for a MOX rod than for an LEU rod in the same position.

BREDL also notes that Duke has admitted that the models used by Duke to compute PCT do not take into account the presence of "hot spots" due to plutonium agglomerates and their impact on local clad temperatures, but only considers averages over a length large compared to the mean agglomerate size. See transcript of 5l2'h meeting of the ACRS at 37-39 (May 6, 2004).

The argument by Duke's representative at the ACRS meeting that localized temperature peaks due to hot spots are not important is not persuasive. Properly accounting for these hot spots could raise the MOX PCT above the result of Duke's calculation, thereby reducing the margin even further.

d. Oxidation potential: Duke assumes that, as used in BREDL's April 14, 2004 discovery response, this refers to oxidation potential of the fuel pellet. If this is not correct, describe the phenomenon asserted.

RESPONSE: Duke's assumption is correct.

e. Linear heat generation rate: Given that LOCA analyses establish acceptable peak linear heat generation rates (LOCA limits), and assuming that the plant operates within the envelope defined by the LOCA limits and the core design, how does the MOX fuel linear heat generation rate constitute a "specific MOX fuel behavior" that will affect a design basis LOCA event?

RESPONSE: BREDL asserts here the fact that at high burnups, the linear heat generation rate for MOX fuel is generally higher than that for LEU fuel. This, in turn, results in increased centerline temperature and stored energy, therefore reducing the margin to design-basis LOCA 5

regulatory limits. BREDL maintains that every reduction in margin associated with MOX fuel use, coupled with the non-conservatism of ignoring fuel relocation effects, reduces confidence in Duke's design-basis LOCA analysis of the MOX LTA core.

f. Fission product release rates and magnitudes: (Given that none of these behaviors is active in a design basis LOCA evaluation under 10 C.F.R. § 50.46, Duke assumes that BREDL considers these behaviors relevant to the LOCA dose calculation.) The MOX fuel lead assembly LOCA dose calculation was based on the TID-14844 source term.2 Is BREDL asserting that the TID-14844 source term is appropriate for cores containing all LEU fuel but not appropriate for cores containing four MOX fuel assemblies? If so, provide the basis and rationale.

2 Letter, U. S. Nuclear Regulatory Commission to H. B. Barron (Duke), Safety Evaluation for Proposed Amendments to the Facility Operating License and Technical Specifications to Allow Insertion of Mixed Oxide Fuel Lead Assemblies, April 5, 2004.

RESPONSE: As clarified by the Board in the telephone conference of April 20,2004, Contention I does not pertain to source term issues. See transcript at 1727-35. The first set of interrogatory responses was filed before we received this clarification. Thus BREDL no longer considers this "behavior" relevant to Contention I.

9. Radial and axial power distribution: As noted above, under "linear heat generation rate," core design defines a plant operating envelope within which peaking is less severe than that assumed in the LOCA analyses. Given this, explain how MOX fuel radial power distribution and axial power distribution affect a LOCA scenario in a manner different from LEU fuel. Does BREDL assert that the MOX fuel radial power distribution and axial power distribution render the MOX fuel design basis LOCA event analyses invalid? If so, explain how.

RESPONSE: BREDL does assert that the MOX fuel radial power distribution and axial power distribution render the MOX fuel design-basis LOCA event invalid, in the following respect.

The axial and radial power distributions in MOX fuel are different that that of LEU fuel, which could affect the evaluation of the impact of fuel relocation on the design-basis LOCA analysis.

For instance, because MOX fuel has a lower thermal conductivity and hence a higher radial 6

temperature gradient than LEU fuel, the stress induced by the stored-energy redistribution during the blowdown phase of a LOCA could be greater for MOX fuel than for LEU fuel, leading to greater fuel fragmentation and more severe relocation effects. See Mailliat and Schwartz at 436 (2002), op cit.

h. Potential for fuel crumbling and relocation following clad ballooning:

Describe BREDL's basis (e.g., test, analysis, papers, treatises, or expert opinion other than Dr. Lyman) to assert that MOX fuel behavior for this phenomenon would be any different from LEU fuel behavior? If there is any reason to suspect a difference, describe how such a difference would render MOX fuel worse than LEU fuel, relative to a design basis LOCA event.

RESPONSE. BREDL notes that the fuel relocation phenomenon has been observed in LEU fuel for rod bumups exceeding around 48 GWD/t. See Mailliat and Schwartz at 432 (2002), op cit.

This suggests that vulnerability to fuel relocation is associated with the development of the high-burnup "rim" region known to emerge in LEU fuel for burnups exceeding about 40-45 GWD/t.

For'MOX fuel, a high-burnup rim-like region emerges in the outer layers of the plutonium agglomerates for much lower rod-average bumups than 40-45 GWD/t, because the local burnups within the plutonium agglomerates increase much more rapidly than the rod-average burnups. Thus.it is reasonable to expect that the onset of fuel relocation in MOX fuel may occur at lower rod-average burnups than in LEU fuel, if it is indeed related to the microstructure changes associated with rim formation. This would imply that MOX fuel will be vulnerable earlier in its irradiation history (and consequently for a longer time) than LEU fuel.

The greater thermo-mechanical stress in MOX fuel during the blowdown phase of a LOCA compared to LEU may also increase its propensity for relocation. See Response to Interrogatory 32(g).

According to two out of four NRC experts who participated in the 2001 PIRT panel on LOCAs and high-bumup fuel, the composition of fuel (i.e. a specified MOX composition) is of 7

"high importance" for consideration of fuel relocation effects because it "may affect the amount of fine grain material after relocation. Fuel structure and mechanical properties are influenced by fuel type." See NUREG/CR-6744, "Phenomenon Identification and Ranking Tables for Loss-of-Coolant Accidents in Pressurized and Boiling Water Reactors Containing High-Burnup Fuel," Appendix D, Table D-1 at D-67 (December 2001). One expert concluded that fuel composition was of moderate importance to relocation, stating that "the consequence of fuel fragments relocation (higher local decay heat and higher cladding temperature) could be more effective with MOX fuel than with U02 fuel" but that "the viscoelastic properties of the MOX should impair the fuel fragments relocation at high burnup." Id. at D-67. A fourth expert concluded that fuel composition would be of only low importance to relocation. Id. at D-67.

This difference of expert opinion highlights the inadequacies of the experimental database with regard to integral tests of MOX fuel under design-basis LOCA conditions, and underscores the significant uncertainties in Duke's design-basis LOCA analysis.

i. Particle size distribution of fuel pellet fragments: Describe the basis (e.g., test, analysis, papers, treatises, or expert opinion other than Dr.

Lyman) for asserting that MOX fuel behavior in this area would be any different from LEU fuel behavior. What is the basis demonstrating that such a difference would render MOX fuel worse than LEU fuel, relative to a design basis LOCA event? If available, quantify the difference.

RESPONSE: See Response to Interrogatory 32(h). In the judgment of two of the experts on the PIRT panel on high-burnup fuel, the amount of fine-grain material after relocation may be affected by the difference between LEU and MOX fuel.

i. Characteristics of fuel relocation: Describe the basis (e.g., test, analysis, or expert opinion) for asserting that MOX fuel behavior in this area would be different from LEU fuel behavior. If there is any reason to suspect a difference, describe BREDL's basis for asserting that such a difference would render MOX fuel worse than LEU fuel, relative to a design basis LOCA event? If so, quantify the difference.

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RESPONSE: See Responses to Interrogatories 32(g)-(i). If MOX fuel produces a greater amount of fine-grain material than LEU, more fuel particles may relocate and greater packing fractions can occur after relocation, with greater corresponding increases in PCT. See Response to Interrogatory 42. This effect will be compounded by the greater local power density of MOX fuel at moderate burnup (40 GWD/t) compared to LEU. BREDL is unable to provide any quantification of the greater vulnerability and more severe consequences of MOX fuel relocation compared to LEU fuel relocation because of the absence of experimental data.

Interrogatorv33 In its April 14,2004 response to Duke's First Set of Interrogatories, Interrogatory 5, BREDL listed a number of specific M5 cladding behaviors that will affect a LOCA scenario. For each of the following, provide the requested additional information:

a. Clad ballooning: How is M5 different from Zircaloy-4 in this regard? Quantify the difference to the extent possible and provide the basis for BREDL's assertion.

RESPONSE: According to IRSN, M5 will form larger balloons than Zircaloy-4 in a design-basis LOCA because it remains more ductile during irradiation. IRSN presentation to NRC at 24 (October 23, 2003). BREDL is unable to quantify this difference as a function of burnup because of an absence of experimental data on the performance of irradiated MS cladding under design-basis LOCA conditions. BREDL notes that the Electric Power Research Institute (EPRI) and Areva (parent company of Framatome ANP) apparently continue to deny NRC access to samples of irradiated high-burnup M5-clad LEU fuel for testing at Argonne National Laboratory. Letter from Ashok C. Thadani, NRC, to David Modeen, EPRI (April 21, 2004), ADAMS Accession Number ML041130490. This lack of cooperation can only cause further delays in the 9

ability of NRC to obtain the experimental data it needs to confirm the safety of high-burnup M5-clad fuel (whether LEU or MOX).

b. Fuel-clad interaction: What specific type of fuel-clad interaction does BREDL assert will affect a LOCA? Is such an asserted interaction a mechanical, nuclear, or chemical interaction? What basis does BREDL have for an assertion that M5 cladding will interact with MOX fuel in a manner that is different from Zircaloy-4 cladding? If there is an asserted difference, how would this difference have an adverse impact on the response to a LOCA?

RESPONSE: See Response to Interrogatory 33(b). In addition, BREDL states that In general, both mechanical and chemical pellet-clad interactions will be affected by differences in clad composition. Since M5 has different mechanical and chemical characteristics than Zircaloy-4, it is clear that it will interact with MOX fuel in a manner that is different from Zircaloy-4 cladding.

BREDL does not have enough information to assert that this difference would have either a beneficial or an adverse impact on the response to LOCA because of the paucity of experimental data regarding irradiated M5-clad MOX fuel. In this regard, BREDL underscores the admission of M. Blanpain of AREVA during the ACRS Reactor Fuels Subcommittee Meeting on April 21, 2004 that MOX fuel irradiated in France is predominantly clad in Zircaloy-4, and only "some M5 fuel rods with MOX for experimental purposes" have been used in France. See Transcript at 61-62. For some reason, France is reluctant to use M5-clad MOX fuel domestically and is primarily producing it for export to Germany (and now to the United States). However, even in Germany the use of M5-clad MOX has been extremely limited. And BREDL is unaware of any integral LOCA tests performed with irradiated M5-clad MOX fuel.

c. Clad oxidation: Given that M5 cladding oxidation properties are superior to Zircaloy-4 (i.e., M5 shows lower corrosion during normal operation), how would M5 clad oxidation lead to adverse impacts in a design basis LOCA?

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RESPONSE: As stated above, the greater retained ductility of M5 as a function of burnup compared to Zircaloy-4 results in greater M5 balloon sizes during a design-basis LOCA for fuel rods of the same burnup. Larger balloons increase the space available for fuel fragments to fall and hence result in a greater propensity for fuel relocation during a LOCA, with an associated increase in PCT and local clad oxidation. Thus the lower corrosion rate of M5 during normal operation may lead to adverse impacts during a design basis LOCA that should be fully accounted for to assess compliance with regulatory limits.

d. Hydrogen uptake: Given that M5 cladding hydrogen uptake is superior to Zircaloy-4 (i.e., M5 shows significantly less hydrogen uptake), how would M5 cladding uptake lead to adverse impacts in a design basis LOCA?

RESPONSE. See response to Interrogatory 33(c).

e. Loss of ductility: Given that all cladding exhibits loss of ductility with burnup, and that M5 performance is better than Zircaloy-4 in this regard (i.e., M5 retains ductility better with burnup), describe how M5 ductility loss would lead to adverse impacts in a design basis LOCA.

RESPONSE: See response to Interrogatory 33(c).

f. Reaction with fission product releases: Duke assumes that the basis of the BREDL response was the fact that advanced cladding alloys (such as M5) are generally characterized by no tin (M5) or lower tin content than Zircaloy-4, along with the fact that the lower tin content has been postulated to contribute to higher tellurium releases during a hypothetical severe accident. Is this correct, or is there another basis for BREDL's response? If so, state that basis. Does BREDL consider tellurium to be a significant contributor to offsite consequences, relative to other radioisotopes? Has BREDL quantified such contribution. If so, describe the quantification.

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RESPONSE: Duke's assumption is correct. However, BREDL does not plan to further respond to this question, as it is relevant to source term issues that were to have been considered in Contention II, which has been dropped. See Response to Interrogatory 32(f).

g. Maximum flow blockage: Given that the MOX fuel LOCA analyses evaluated the M5 cladding with worst-case (unirradiated) properties with respect to ballooning, describe the basis for BREDL's position that the analyses are non-conservative with respect to ballooning and flow blockage.

RESPONSE: The maximum flow blockage that will preserve a coolable geometry depends on the assumed heat source and the heat transfer properties of the fuel bundle.

As IRSN points out, acceptable bundle blockage ratios were derived based upon arrays of unirradiated fuel rods, and did not take into account any fuel relocation and its associated impacts on the redistribution of the decay heat source within the fuel rods. IRSN presentation to NRC at 29 (October 23, 2003), op cit. Thus any analysis that does not take this into account is incomplete and may be non-conservative.

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Interrogatora34 In response to Interrogatory 9, regarding the ability of computer codes to assess the impact of MOX fuel behavior differences, BREDL's April 14, 2004 Response states that "BREDL shares the skepticism of the Expert Panel on Source Terms for High-Burnup and MOX Fuels." Is it not true that the comments of the Expert Panel were directed exclusively at codes used to analyze severe accidents, not evaluation models for design basis LOCAs and compliance with 10 CFR § 50.46? Does BREDL assert that the Expert Panel statement is relevant to a design basis LOCA evaluation model? If so, describe the basis for such position.

RESPONSE: In reviewing the context of the above-mentioned quotation, BREDL now believes that it is unclear whether the Expert Panel's remark was intended to apply only to severe accident codes or to design basis LOCA codes as well. However, given the sparse nature of the experimental database, BREDL believes that current computer models for the behavior of MOX fuel during design-basis LOCA conditions are inadequately validated.

Interrogatorv35 In response to Interrogatory 10, BREDL states that 'BREDL does not assert that Duke fails to comply with Appendix K." If the MOX fuel LOCA analysis complies with 10 C.F.R. Part 50, Appendix K, describe how the analysis is not adequate to demonstrate acceptable emergency core cooling system performance.

RESPONSE: Acceptable emergency core cooling system performance is determined by compliance with both 10 CFR Part 50 Appendix K and 10 CFR § 50.46. Emergency core cooling systems must also provide adequate protection of public health and safety.

NRC has acknowledged that omission of fuel relocation effects is a non-conservatism in Appendix K, and that an early "resolution" of this issue (Generic Issue 92) may have been in error or is no longer applicable because of new information. Memorandum from Ashok C.

Thadani to Samuel J. Collins re: Research Information Letter 0202, Revision of 10 CFR § 50.46 and Appendix K, Attachment 4 at 4-5 (June 2002). Given the potential impact on PCT of relocation effects, the continued omission of relocation calls into question the overall conservatism of Appendix K models. See Response to Interrogatory 42.

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Interrogatorv36 In response to Interrogatory 12, BREDL states that ". . . the likelihood and progression of fuel relocation during a design basis LOCA will in general be different between the MOX LTAs and conventional LEU fuel." BREDL cites three differences (fuel-clad interaction, particle size distribution of fuel fragments, and the clad ballooning geometry). Describe how each cited difference will affect relocation and in what manner. Also, describe the quantitative and qualitative bases for your conclusion.

RESPONSE. See Responses to Interrogatories 32 (g)-(j).

Interrogatorv37 In response to Interrogatory 13, BREDL states that IRSN postulated a PCT increase of 180'F due to fuel relocation. Please confirm whether BREDL's position is that IRSN is referring to fuel relocation in general during a design basis LOCA, and not specifically to fuel relocation in MOX fuel during a design basis LOCA.

RESPONSE: To the best of BREDL's recollection, IRSN did not specify during the October 23, 2003 NRC briefing whether the 180'F increase in PCT due to fuel relocation was applicable only to a particular fuel type (MOX or LEU). However, IPSN fuel relocation calculations attached to a document that BREDL received from the NRC staff in response to BREDL's first discovery request, clearly refer to U0 2 at a burnup of 57 GWd/tU. "Overview of HRP LOCA Experiment,"

Issue 2, Annex IV (February 2003). Because the impact of relocation for MOX may be more severe than for U0 2 , one may expect that the associated temperature increase would be even greater for MOX. See Responses to Interrogatories 32 (g) - ().

Interroigatorv38 In response to Interrogatory 13, BREDL notes that the Framatome ANP analysis of MOX fuel during a design basis LOCA does not model fuel relocation and its effects. BREDL notes that 1800 F is a "significant change" as defined in 10 CFR § 50.46(a)(3)(i), and implies that the regulations therefore require the Framatome ANP evaluation model to address fuel relocation. Is this an accurate statement of BREDL's position? If not, explain BREDL's position and describe the basis for that position.

Also, is it BREDL's view that the 180'F value would apply to LEU fuel as well?

RESPONSE: BREDL maintains that the provision in 10 CFR § 50.46(a)(3)(i) applies to all "acceptable evaluation models," whether they pertain to 10 CFR § 50.46(a)(1)(i) "realistic" models or to Appendix K models. If NRC cannot tolerate uncertainties in PCT greater than 500 F in "realistic" models, then it should not tolerate them in Appendix K models.

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Interrozatorv39 In response to Interrogatory 13, BREDL states that ". . . an M5-clad MOX LTA forms fragments at lower burnups than Zircaloy-clad LEU fuel." Describe the basis for this statement.

RESPONSE: See Responses to Interrogatories 32 (g)-(h).

Interrogatorv40 In response to Interrogatory 13, BREDL states that "MOX fuel has a higher linear heat generation rate." However, by the nature of the proposed Catawba Technical Specifications for MOX fuel lead assemblies, the MOX fuel must be non-limiting. Therefore, the linear heat generation rate of MOX fuel will be lower than the linear heat generation rate of at least some LEU fuel. Given this fact, explain how linear heat generation rate can support BREDL's conclusion that fuel relocation will be more severe for MOX fuel than for LEU fuel.

RESPONSE: BREDL agrees with Duke's statement that "the linear heat generation rate of [the four] MOX fuel [LTAs] will be lower than the linear heat generation rate of at least some LEU fuel." However, linear heat generation rate is only one of the many parameters that contribute to a potentially more severe fuel relocation effect for MOX than for LEU. Duke cannot establish that the MOX LTAs will indeed be non-limiting with respect to design-basis LOCAs unless it fully assesses the impact of fuel relocation both for LEU assemblies and for the MOX LTAs.

Interrozatorv41 In response to Interrogatory 13, BREDL states that "MOX fuel develops a larger balloon because of the greater ductility of M5 cladding." Explain the comparison (i.e., greater than what, and at what conditions?). Is this a comparison to Zircaloy-4 or to ZIRLO?

RESPONSE: See Response to Interrogatory 33(a). This is a comparison to both Zircaloy-4 and ZIRLO, which apparently has an oxidation behavior intermediate between Zircaloy-4 and M5.

See Y. Yan, T. Burtseva and M. Billone, "LOCA Results for Advanced-Alloy and High-Bumup Zircaloy Cladding, NRC Staff's Response to BREDL's First Set of Discovery Requests to the NRC Staff, Document 25 of Documents Responsive to Specific Document Request I-2, undated, no page numbers.

Interrogatorv42 In response to Interrogatory 13, BREDL states that fuel relocation can result in an increase in peak cladding temperature of 1800 F. Describe the calculation upon which this statement is based. For both the base calculation and the calculation 15

modeling fuel relocation, discuss (1) how the cladding rupture and fuel relocation phenomena were modeled, (ii) the packing factor that was assumed for relocated fuel, and (iii) whether or not credit was taken for extra cooling due to rupture-inducted turbulence. Also describe the evaluation model that was used to perform the calculation, and the plant type that was analyzed.

RESPONSE: BREDL does not know the details of how the IRSN fuel relocation calculations were conducted, but only has access to some results. As described in the Response to Interrogatory 37, BREDL now has additional results of IPSN calculations of the impact of fuel relocation on PCT as a function of filling ratio. Overview of HRP LOCA Experiment, Annex 4 (2003), op cit. The calculations were carried out for a LB-LOCA using the CATHARE2 code, Vl.3L, for PWR U0 2 fuel at 57 GWd/tU burnup. By comparing the information in Figure 1 and Figure 9 of that document, one sees that the PCT increases by approximately 30'C (540) to 190 0C (3420F) for filling ratios of 40 to 70%, respectively. The NRC staff appears to be familiar with this result. See Research Information Letter 0202, Attachment 5 at 4 (June 2002), op cit.' This result makes clear the strong dependence of PCT on filling ratio when relocation occurs. These differences are without a doubt highly significant for a design basis LOCA analysis, especially when MOX fuel assemblies are present in the core, given the potential that fuel relocation may be more severe for MOX fuel, as discussed above.

Interrozatorv 43 In response to Interrogatory 15, BREDL states that "uncertainties regarding the behavior of the MOX LTAs under design basis LOCA conditions are sufficiently large that high assurance of compliance with NRC requirements cannot be provided." What, specifically, does BREDL mean by "high assurance?" Does BREDL believe that the NRC "reasonable assurance" standard does not apply to the MOX fuel lead assembly license amendment request?

The NRC cites an increase of 313'F in PCT associated with relocation and a 70% filling fraction from a 2001 IPSN paper. BREDL does not have this paper.

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RESPONSE: BREDL did not intend the phrase "high assurance" to have a precise regulatory significance. BREDL acknowledges that the applicable regulatory standard is "reasonable assurance."

Interrogatory44 In response to Interrogatory 15, BREDL states that "uncertainties regarding the behavior of the MOX LTAs" are too large to permit the lead assembly program to go forward. Would BREDL agree, however, that lead assembly programs, by their very nature, are intended to gather data to reduce uncertainty?

RESPONSE: BREDL agrees that one purpose of lead test assembly programs is to gather data on fuel assemblies to reduce uncertainty. But in order for such tests to be conducted at NRC-licensed reactors, there must be a sufficient quantity of experimental data already acquired to provide reasonable assurance that the test program itself will not compromise adequate protection of public health and safety. If sufficient data to satisfy this regulatory requirement does not exist, then further testing under carefully controlled experimental conditions must be carried out. This is why BREDL believes that additional data on MOX fuel performance under design-basis LOCA conditions must be acquired at experimental facilities such as Halden and Ph6bus before NRC can have confidence in the safety of the MOX LTA program at Catawba, which is not a test facility but a commercial power plant. BREDL is not establishing a "Catch-22," as Duke has suggested in the past, given the existence of MOX programs overseas that have already been licensed under the regulatory systems of their host countries (which, incidentally, has no direct relevance to NRC approval of such tests in the United States).

Interroggatorv45 In response to Interrogatory 16, BREDL states that "BREDL considers the information from the VERCORS tests to be germane to the performance of MOX fuel during a design basis LOCA, as does the Expert Panel Report on Source Terms." Does BREDL agree that the VERCORS tests and results are irrelevant to the issue of MOX fuel compliance with 10 CFR § 50.46 emergency core cooling system requirements?

Does BREDL agree that to the extent the VERCORS tests are relevant, it is in relation to dose analyses only? If not, describe the basis for BREDL's position.

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RESPONSE: BREDL agrees that the VERCORS tests are relevant to dose analyses only when design-basis LOCAs are considered.

Interrogatory46 In connection with Duke's license amendment application ("LAR"), the NRC Staff issued a Safety Evaluation Report ("SER") on April 5, 2004, addressing many of the issues raised in BREDL's Interrogatories 4 though 22. The Staff determined that Duke's LAR demonstrates with reasonable assurance satisfaction of LOCA criteria in 10 C.F.R. § 50.46 and 10 CFR Part 50 Appendix K, as well as meeting LOCA radiological consequences through independent NRC radiological analysis. In this context, please respond to the following:

a. In connection with the SER's findings regarding LOCA for LAR Sections 2.1, 2.2, 2.3, 2.4, 2.7, 3.0, 3.1, 3.2, 3.3 and 4.0, indicate each specific error that BREDL asserts in the NRC evaluation and analysis.

RESPONSE: BREDL finds it impossible to identify specific errors in the NRC evaluation and analysis of Duke's LAR contained in the April 5, 2004, SER, since the NRC provides absolutely no detail in that document to support its conclusion, other than a restatement of Duke's own results. In fact, NRC has itself admitted that'it did not do any independent calculations of LOCAs for the MOX LTA core to verify Duke's own analysis. See transcript of April 21, 2004, ACRS Reactor Fuels Subcommittee Meeting at 213-214.

BREDL asserts that the fundamental error in NRC's approval of Duke's design basis LOCA analysis is the omission of consideration of relocation effects and the potential for M5-clad MOX LTAs to experience a more severe impact from relocation than LEU assemblies. It has already been established that the NRC not require consideration of fuel relocation in Appendix K models. However, the lead reviewer of the Duke LAR LOCA analysis admitted that he had not even given the matter any thought, even though the NRC staff already had ample evidence (e.g. the Halden report referenced above) that relocation could have a very severe 18

impact on the PCT in a design basis LOCA. See transcript of April 21, 2004, ACRS Reactor Fuels Subcommittee Meeting at 216.

b. Provide the supporting basis for each asserted error and supporting documentation for each asserted error.

RESPONSE: See the Responses to Interrogatories 32(b), 32(c), 32(e)-(j), 33(l)-(d), 33(g), 37, 42.

C. Describe how, in BREDL's view, these asserted errors individually or collectively would change overall conclusions in the SER.

RESPONSE: BREDL has provided evidence above that accounting for the potential impact of relocation on Duke's design-basis LOCA calculation could lead to an increase in the calculated MOX PCT of as much as several hundred degrees Fahrenheit, depending on the filling ratio.

Since there is little or no experimental data to conclusively validate the impact of relocation on either LEU or MOX fuel, a design-basis MOX LTA LOCA analysis that takes relocation into account would be highly uncertain --- with a resulting large uncertainty in the calculation of the relocation-associated increase in PCT of a MOX LTA fuel rod compared to the relocation-associated increase in PCT of an LEU fuel rod. For instance, if the MOX packing fraction is 70% and the LEU packing fraction is only 40%, the increase in PCT could be nearly three hundred degrees Fahrenheit greater for MOX than for LEU. See Response to Interrogatory 42.

That uncertainty would have to be reflected in Duke's analysis, and NRC approval would be contingent upon a demonstration that uncertainties of this magnitude do not undermine reasonable assurance of adequate protection of the public health and safety.

d. For every fuel behavior (BREDL Interrogatory Response 4), cladding behavior (BREDL Interrogatory Response 5),

and fuel property (BREDL Interrogatory Response 6),

identify the NRC regulatory guidance that identifies this behavior or property as a factor for consideration in design basis accidents.

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RESPONSE: All fuel and cladding behaviors and properties listed in BREDL's response to Interrogatories 4 through 6 are relevant to compliance with the regulatory requirements of 10 CFR §50.46 and Part 50 Appendix K, as well as to the overarching requirement that adequate protection of the public health and safety be maintained.

IV. BREDL CONTENTIONS II AND III BREDL has withdrawn Contention II and Contention III has been dismissed. Therefore, BREDL will not answer interrogatories related to those contentions.

Declaration of Dr. Edwin S. Lyman I certify that the facts in the foregoing discovery responses are true and correct to the best of my knowledge, and that the opinions expressed therein are based on my best professional judgment.

Dr. Edwin S. Lyman Respectfully submitted, iane Curran Harmon, Curran, Spielberg, & Eisenberg, L.L.P.

1726 M Street N.W., Suite 600 Washington, D.C. 20036 202/328-3500 e-mail: deurran(i)harmoncurran.com June 8, 2004 20