RA-18-0185, Response to Request for Additional Information (RAI) Regarding 10 CFR 50.46 Annual Report, Including Revised Robinson Large Break Loss of Coolant Accident Report

Response to Request for Additional Information (RAI) Regarding 10 CFR 50.46 Annual Report, Including Revised Robinson Large Break Loss of Coolant Accident Report

ML18344A656
Person / Time
Site:	Robinson
Issue date:	12/10/2018
From:	Donahue J Duke Energy Progress
To:	Document Control Desk, Office of Nuclear Reactor Regulation
Shared Package
ML18345A114	List: RA-18-0185, Response to Request for Additional Information (RAI) Regarding 10 CFR 50.46 Annual Report, Including Revised Robinson Large Break Loss of Coolant Accident Report
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RA-18-0185
Download: ML18344A656 (20)

Text

JOSEPH DONAHUE Vice President Nuclear Engineering 526 South Church Street, EC-07H Charlotte, NC 28202 980-373-1758 Joseph.Donahue@duke-energy.com PROPRIETARY INFORMATION - WITHHOLD UNDER 10 CFR 2.390 UPON REMOVAL OF ATTACHMENT 3 THIS LETTER IS UNCONTROLLED Serial: RA-18-0185 10 CFR 50.46 December 10, 2018 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 H. B. ROBINSON STEAM ELECTRIC PLANT, UNIT NO. 2 DOCKET NO. 50-261 / RENEWED LICENSE NO. DPR-23

SUBJECT:

Response to Request for Additional Information (RAI) Regarding 10 CFR 50.46 Annual Report, Including Revised Robinson Large Break Loss of Coolant Accident Report

REFERENCES:

1. Duke Energy letter, Carolinas, LLC (Duke Energy) Annual Report of Changes Pursuant to 10 CFR 50.46, dated May 24, 2018 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML18150A705)

2. NRC email, Robinson RAIs - Duke Energy 10 CFR 50.46 Annual Report (EPID L-2018-LRO-0028), dated October 17, 2018 (ADAMS Accession No. ML18291A644)

Ladies and Gentlemen:

In Reference 1, Duke Energy Progress, LLC (Duke Energy) submitted an annual report of changes or errors in Emergency Core Cooling System (ECCS) evaluation models pursuant to 10 CFR 50.46(a)(3)(ii) for, among others, H. B. Robinson Steam Electric Plant, Unit No. 2 (RNP). In Reference 2, the NRC requested additional information regarding Reference 1. provides Duke Energys response to the Reference 2 RAI, which includes a revision to the Reference 1 annual 10 CFR 50.46 reporting table for the RNP Large Break Loss of Coolant Accident (LBLOCA) analysis. Attachment 3 provides information from a Framatome letter to Duke Energy that supports the Attachment 1 RAI responses. Attachment 3 contains information that is proprietary to Framatome. In accordance with 10 CFR 2.390, Duke Energy requests that Attachment 3 be withheld from public disclosure. An affidavit is included (Attachment 2) attesting to the proprietary nature of Attachment 3. A non-proprietary version of is included in Attachment 4.

PROPRIETARY INFORMATION - WITHHOLD UNDER 10 CFR 2.390 UPON REMOVAL OF ATTACHMENT 3 THIS LETTER IS UNCONTROLLED

PROPRIETARY INFORMATION -WITHHOLD UNDER 10 CFR 2.390 UPON REMOVAL OF ATTACHMENT 3 THIS LETTER IS UNCONTROLLED U.S. Nuclear Regulatory Commission RA-18-0185 Page2 No new commitments have been made in this submittal. If you have additional questions, please contact Mr. Art Zaremba, Manager - Regulatory Affairs, at 980-373-2062.

Joseph Donahue Vice President - Nuclear Engineering JD/jbd Attachments:

1. Response to Request for Additional Information

2. Framatome Affidavit

3. Information from Framatome Letter, "Impact of Swelling and Rupture Model Application on Robinson Cycle 28 RLBLOCA Analysis," Dated November 21, 2018 (Proprietary)

4. Information from Framatome Letter, "Impact of Swelling and Rupture Model Application on Robinson Cycle 28 RLBLOCA Analysis," Dated November 21, 2018 (Redacted) cc:

C. Haney, Regional Administrator USNRC Region II D. Galvin, NRR Project Manager N. Jordan, NRR Project Manager - RNP L. Garner, Manager, Radioactive and Infectious Waste Management Section (SC)

(Without Attachment 3)

A. Wilson, Attorney General (SC) (Without Attachment 3)

S. E. Jenkins, Chief, Bureau of Radiological Health (SC) (Without Attachment 3)

PROPRIETARY INFORMATION -WITHHOLD UNDER 10 CFR 2.390 UPON REMOVAL OF ATTACHMENT 3 THIS LETTER IS UNCONTROLLED RA-18-0185 Attachment 1 Response to Request for Additional Information RA-18-0185 Page 1 of 5 See ML18291A644 (Reference 2) for complete text of the NRC request for additional information (RAI) and preface to the following questions.

NRC RAI Questions Therefore, the NRC staff requests that Duke Energy provide the following additional information in support of our review of the annual report of LOCA evaluation model changes and errors for H.B. Robinson submitted in accordance with 10 CFR 50.46(a)(3)(ii):

(a) A revision to the 2017 annual report of changes and errors submitted to address 50.46(a)(3)(ii), which acknowledges and estimates the impacts of the apparent errors in the existing large-break LOCA evaluation model applied to H.B. Robinson that are associated with (1) the incorrect computation of cladding oxidation and (2) the nonconservative neglect of cladding swelling and rupture based upon the vendors submission of erroneous information.

(b) If the peak cladding temperature impact of these errors is significant, please further provide a 30-day error report in accordance with 10 CFR 50.46(a)(3)(ii).

(c) Confirmation that all requirements of 10 CFR 50.46(b) are satisfied once the effects of the above errors have been taken into account, or a description of the immediate steps necessary to bring plant design or operation into compliance in accordance with 10 CFR 50.46(a)(3)(ii).

(d) Adequate description of and justification for the method used to estimate the impacts of the errors described above.

Duke Energy Response to NRC RAI Question Part (a)

Framatome performed a quantitative evaluation to address the RAI. The details are provided in / 4. The estimated impact to peak cladding temperature (PCT) was +31 °F. With consideration of previously reported changes, the H. B. Robinson Large Break Loss of Coolant Accident (LBLOCA) licensing basis PCT value is 2119 °F. A revised 10 CFR 50.46 reporting table is provided below for the Robinson LBLOCA analysis. Since this issue only affects the Robinson LBLOCA analysis, all other PCT reporting contained within Reference 1 remains valid.

RA-18-0185 Page 2 of 5 10 CFR 50.46 Report for H. B. Robinson Unit 2 - Large Break LOCA Plant: H. B. Robinson, Unit 2 Reporting Period: January 1, 2017 - December 31, 2017 LOCA Analysis Type (if applicable): Large Break Evaluation Model: EMF-2103(P)(A), Revision 0 Realistic Large Break LOCA for PWRs Fuel: 15x15 HTP A. Analysis of Record PCT 2084 °F B. Net Cumulative 10 CFR 50.46 Net PCT Effect Absolute PCT Effect Changes and Error Corrections

- Previously Reported +4 °F 24 °F C. Baseline PCT for assessing new changes for significance (A + B) 2088 °F D. Cumulative 10 CFR 50.46 Changes and Error Corrections

- This Reporting Period

1. Estimated effect of including a fuel +31 °F clad swelling and rupture model, inclusive of (1) M5 LOCA swelling and rupture model update and (2) error corrections to cladding oxidation calculation due to use of cold cladding dimensions.

E. Sum of 10 CFR 50.46 Changes and Net PCT Effect Absolute PCT Effect Error Corrections against Baseline PCT +31 °F 31 °F F. Licensing Basis PCT (C + E) 2119 °F Note: The reporting period is retained as the 2017 calendar year, even though the Framatome evaluation for clad swelling and rupture effects was performed in 2018. This is consistent with the NRC-requested submission of a revised 10 CFR 50.46 annual report for the 2017 calendar year, and the original notification date in 2017 of the clad swelling and rupture error discovery by Framatome to Duke Energy.

RA-18-0185 Page 3 of 5 Duke Energy Response to NRC RAI Question Part (b)

The Robinson LBLOCA analysis of record PCT is 2084 °F. Prior to 2017, two separate non-zero changes were previously reported against the analysis of record, with a net change of

+4 °F. The resulting licensing basis PCT value of 2088 °F is described in Robinson UFSAR Section 15.6.5.3, and is used to establish the baseline PCT value for assessing significance to subsequent PCT changes or error corrections. This process for establishing a baseline PCT corresponding to the PCT value cited in the UFSAR is acceptable to NRC staff, as outlined in SECY-16-0033 [see ML15238B016 (FRN)].

The estimated impact to the Robinson LBLOCA analysis is +31 °F to address the inclusion of clad swelling and rupture. Since this estimated impact is less than 50 °F, the change is not significant, and the corresponding requirements at 10 CFR 50.46(a)(3)(ii) for a significant change do not apply.

Since the estimated impact on Robinson LBLOCA PCT is not significant, the requirement in 10 CFR 50.46(a)(3)(ii) to provide a proposed schedule for LOCA reanalysis is not applicable.

For full transparency, it is noted that LOCA reanalyses for Robinson are currently underway to support operation for Cycle 33. The Robinson Large Break LOCA reanalyses will employ the methodology described in Framatome Topical Report EMF-2103, Rev. 3 which explicitly includes the effects of clad swelling and rupture. Therefore, the length of time which Robinson will have to carry the +31 °F PCT penalty for clad swelling and rupture effects on the 10 CFR 50.46 reporting record will be limited in duration. Robinson Cycle 33 is scheduled to begin operation in the Fall of 2020.

RA-18-0185 Page 4 of 5 Duke Energy Response to NRC RAI Question Part (c)

With consideration of previously reported changes, and the +31 °F increase for the inclusion of clad swelling and rupture, the Robinson LBLOCA licensing basis PCT value is 2119 °F. This value is below the PCT limit of 2200 °F per 10 CFR 50.46(b)(1).

As part of the quantitative evaluation to address clad swelling and rupture effects, Framatome evaluated the impact on maximum local oxidation and core-wide oxidation for the Robinson LBLOCA analysis. The values for the transient calculation of oxide are presented in Table A-1 of Attachment 3 / 4. The criteria related to the oxidation process, 10 CFR 50.46(b)(2) and (b)(3), continue to be met in consideration of these values.

The effects of combined loads (LOCA + seismic) on the fuel assembly components have been evaluated by the fuel vendor and the resulting loads are below the allowable stress limit for all the components. The errors related to clad swelling and rupture in the PCT analysis do not affect the LOCA loading evaluations. The combination of compliance with the PCT and maximum oxidation criteria, and the LOCA loads evaluation demonstrates compliance with 10 CFR 50.46(b)(4) criterion for coolable geometry.

The increased energy in the fuel cladding due to inclusion of clad swelling and rupture effects does not persist into the long-term cooling phase of the LBLOCA event, as mitigated by existing emergency operating procedures. Therefore, impacts to the long-term core cooling criteria per 10 CFR 50.46(b)(5) are considered insignificant when the effects of clad swelling and rupture are considered.

RA-18-0185 Page 5 of 5 Duke Energy Response to NRC RAI Question Part (d)

To demonstrate the impact of including a swelling and rupture model on the Robinson LBLOCA analysis of record (AOR), Framatome performed an explicit evaluation using the same S-RELAP5 input file from the limiting PCT case in the AOR. Similarly, the S-RELAP5 code version used is the same as that which was used for the AOR except for the updates associated with the two clad swelling and rupture related changes and errors identified in 2017. The clad swelling and rupture models used in the Robinson evaluation were the same swelling and rupture models that were previously used to support licensing actions for LBLOCA analyses for Shearon Harris, as described in Section 6.9 of Reference 3. Additional details of the Robinson LBLOCA swelling and rupture evaluation performed by Framatome are contained in / 4.

The Robinson swelling and rupture evaluation performed by Framatome is a justifiable estimate for impacts to PCT, since it employs the Robinson LBLOCA limiting case from the AOR, with explicit S-RELAP5 code changes to address the clad swelling and rupture related changes and errors identified in 2017.

Robinson has several evaluation model changes and errors which have been applied to AOR PCT prior to 2017. The summation of those changes and errors results in a net PCT of +4 °F, for a total LBLOCA PCT of 2088 °F (Reference 1). None of these previously reported items changed the fundamental transient evolution of the Robinson LBLOCA event. Furthermore, none of the associated PCT estimates previously reported would be changed or exacerbated by the swelling and rupture phenomena. Accordingly, the previously reported net PCT of

+4 °F remains applicable for Robinson.

References

1. Duke Energy letter, Carolinas, LLC (Duke Energy) Annual Report of Changes Pursuant to 10 CFR 50.46, dated May 24, 2018 (ADAMS Accession No. ML18150A705)

2. NRC email, Robinson RAIs - Duke Energy 10 CFR 50.46 Annual Report (EPID L-2018-LRO-0028), dated October 17, 2018 (ADAMS Accession No. ML18291A644)

3. Framatome Report ANP-3001P, Revision 1, Harris Nuclear Plant Unit 1 Realistic Large Break LOCA Analysis (Enclosure 3 of ADAMS Accession No. ML11238A077)

RA-18-0185 Attachment 2 Framatome Affidavit

AFFIDAVIT COMMONWEALTH OF VIRGINIA )

) ss.

CITY OF LYNCHBURG )

1. My name is Nathan E. Hottle. I am Manager, Product Licensing, for Framatome Inc. (Framatome) and as such I am authorized to execute this Affidavit.

2. I am familiar with the criteria applied by Framatome to determine whether certain Framatome information is proprietary. I am familiar with the policies established by Framatome to ensure the proper application of these criteria.

3. I am familiar with the Framatome information contained in the following document: Duke Energy Letter RA-18-0185, "Response to Request for Additional Information (RAI) Regarding 10 CFR 50.46 Annual Report," referred to herein as "Document." Information contained in this Document has been classified by Framatome as proprietary in accordance with the policies established by Framatome Inc. for the control and protection of proprietary and confidential information.

4. This Document contains information of a proprietary and confidential nature and is of the type customarily held in confidence by Framatome and not made available to the public. Based on my experience, I am aware that other companies regard information of the kind contained in this Document as proprietary and confidential.

5. This Document has been made available to the U.S. Nuclear Regulatory Commission in confidence with the request that the information contained in this Document be withheld from public disclosure. The request for withholding of proprietary information is made in accordance with 10 CFR 2.390. The information for which withholding from disclosure is

requested qualifies under 10 CFR 2.390(a)(4) Trade secrets and commercial or financial information."

6. The following criteria are customarily applied by Framatome to determine whether information should be classified as proprietary:

(a) The information reveals details of Framatome's research and development plans and programs or their results.

(b) Use of the information by a competitor would permit the competitor to significantly reduce its expenditures, in time or resources, to design, produce, or market a similar product or service.

(c) The information includes test data or analytical techniques concerning a process, methodology, or component, the application of which results in a competitive advantage for Framatome.

(d) The information reveals certain distinguishing aspects of a process, methodology, or component, the exclusive use of which provides a competitive advantage for Framatome in product optimization or marketability.

(e) The information is vital to a competitive advantage held by Framatome, would be helpful to competitors to Framatome, and would likely cause substantial harm to the competitive position of Framatome.

The information in this Document is considered proprietary for the reasons set forth in paragraphs 6(c) and 6(d) above.

7. In accordance with Framatome's policies governing the protection and control of information, proprietary information contained in this Document has been made available, on a limited basis, to others outside Framatome only as required and under suitable agreement providing for nondisclosure and limited use of the information.

8. Framatome policy requires that proprietary information be kept in a secured file or area and distributed on a need-to-know basis.

9. The foregoing statements are true and correct to the best of my knowledge, information, and belief.

SUBSCRIBED before me this _,.___.

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day of /V00 ?-a:bb ...r , 2018.

Laurie S. Harris NOTARY PUBLIC, COMMONWEALTH OF VIRGINIA, CITY OF LYNCHBURG MY COMMISSION EXPIRES: 9/30/2020 Reg. # 204707 RA-18-0185 Attachment 3 Information from Framatome Letter, Impact of Swelling and Rupture Model Application on Robinson Cycle 28 RLBLOCA Analysis, Dated November 21, 2018 (Proprietary)

Note: Text that is within bolded brackets is proprietary to Framatome.

RA-18-0185 Attachment 4 Information from Framatome Letter, Impact of Swelling and Rupture Model Application on Robinson Cycle 28 RLBLOCA Analysis, Dated November 21, 2018 (Redacted)

Note: Text that is within bolded brackets is proprietary to Framatome and has been removed.

In 2012, Progress Energy submitted a Robinson RLBLOCA licensing PCT for the transition to fuel with M5 1 cladding (Ref. [i]), supported by the Cycle 28 RLBLOCA uncertainty analyses with MS fuel. This MS analysis was performed with EMF-2103 Revision 0, as supplemented by the transition package (TRN) in 2011 and that analysis is referred to herein as the Analysis of Record (AOR). The TRN-based PCT for Robinson is 2084°F and was determined from S-RELAP5 calculations without a swelling and rupture model. With additional t.PCTs, the current licensing PCT for Robinson is 2088°F.

In 2017 Framatome had two changes and errors that impacted S-RELAP5 calculations when swelling and rupture was modeled (Condition Report (CR) 2017-3565, CR 2017-5630).

To demonstrate the impact of including a swelling and rupture model on the Robinson RLBLOCA AOR, the same S-RELAP5 swelling and rupture model which was used for the Harris TRN swell, rupture, and relocation (SRR) analyses is utilized, but with the options selected as relevant to this RAI.

The general characteristics of the TRN-applied SRR model are described in the Harris licensing submittal, Section 6.9 of Reference [ii] . [

] Therefore, an analysis with this S-RELAP5 swelling and rupture model (S&R model) provides a conservative estimate of the potential impact of swelling and rupture .

To isolate the impact of including an S&R model, there are no other changes to the AOR input files except for activation of the model. Similarly, the S-RELAP5 code version used is the same as that which was used for the AOR except for the updates associated with the two 2017 swelling and rupture related changes and errors. Case 24 with LOOP is the limiting case from the Robinson AOR. [

J Since metal-water reaction is exponentially-dependent on temperature, and rupture results in double-sided oxidation, this AOR case will remain limiting when an S&R model is applied with the code updated for the 2017 issues.

The limiting values from the S&R analysis are shown in Table A-1. The sequence of events is shown in Table A-2 . The limiting rod is the fresh 8% gad rod. It ruptured at 14.8 seconds and had a PCT of 2115°F at 29.7 seconds. The PCT node is the same as the rupture node. The PCT independent of elevation for the limiting rod is shown in Figure A-1. A focused plot of the limiting node cladding temperature over the first 60 seconds of the transient is shown in Figure A-2 . To clearly demonstrate the temperature dependent nature of the metal-water reaction, the figure also shows the cladding temperature of the hot assembly. Following the blowdown heat up , the hot rod temperature rise parallels that of the hot assembly. With the pressure differential across the clad and rising temperature, the cladding begins to swell. Initially, the swelling provides a slight cooling effect. With cladding rupture, there is a local increase in the strain (i.e. balloon size) and energy addition from both the internal and external metal-water reaction. At this time, since the metal-water reaction is exponentially dependent on temperature, the slope of the hot rod temperature rise increases relative to that of the hot assembly. The cladding temperature rise is turned over once there is adequate cooling at the higher core levels.

The value of 2115°F represents the PCT that would have been calculated had an explicit S-RELAP5 swelling and rupture model been included with an S-RELAP5 version updated for the 2017 swelling and rupture related changes and errors. This is an increase of 31°F above the previously calculated AOR value of 2084°F.

1 MS is a trademark or registered trademark of Framatome Inc.

As stated above, Robinson has several evaluation model changes and errors which have been applied to AOR PCT prior to 2017. The summation of those changes and errors results in a net t.PCT of +4°F (2088°F, Ref. [iii]). None of these items changed the fundamental transient evolution of the Robinson LBLOCA event. Furthermore, none of the associated t.PCT estimates previously reported would be changed or exacerbated by the swelling and rupture phenomena. Accordingly, the +4°F remains applicable. Therefore, the final PCT is 2119°F and is less than the 10 CFR 50.46 PCT limit of 2200°F (Table A-3). The local oxidation and whole core hydrogen also remain well within the 10 CFR 50.46 acceptance criteria.

References

[i]. Letter from Richard Hightower (Progress Energy) to US NRC "Report of Changes to or Errors Discovered in an Acceptable Loss-Of-Coolant Accident Evaluation Model Application for the Emergency Core Cooling System," ML12128A057.

[ii] . ANP-3011 P Rev. 001 , "Harris Nuclear Plant Unit 1 Realistic Large Break LOCA Analysis,"

Enclosure 3 of ML11238A077.

[iii]. Letter from Joseph Donahue, Duke Energy to U.S. NRC "Carolinas, LLC (Duke Energy) Annual Report of Changes Pursuant to 10 CFR 50.46," ML18150A705.

Table A-1 S&R Case Limiting Values Parameter Limiting Value PCT (°F) 2115 Transient MLO (%) 5.27 Core Wide Oxidation(%) 0.0338 Table A-2 S&R Case Sequence of Events Time Event (sec)

Begin Analysis 0 Break Opened 0 SIAS Issued 0.5 Start of Broken Loop Accumulator Injection 8.3 Start of Intact Loop Accumulator Injection (Loop 2, 3) 10.7, 10.7 Rod Rupture 14.8 Beginning of Core Recovery/Reflood 28.1 PCT Occurred 29.7 HHSI Available 40.5 Broken Loop HHSI Delivery Began 40.5 Intact Loop HHSI Delivery Began (Loop 2, 3) 40.5, 40.5 LHSI Available 44.5 Broken Loop LHSI Delivery Began 44.5 Intact Loop LHSI Delivery Began (Loop 2, 3) 44.5, 44.5 Broken Loop Accumulator Emptied 49.6 Intact Loop Accumulator Emptied (Loop 2, 3) 50.8, 48.1 Transient Calculation Terminated 382.7

Table A-3 Summation of ~PCT Estimates PCT Delta PCT Analysis Year Notes (OF) (OF)

Analysis of Record 2084 2011 CR 2011-7155 +14 2011 Sleicher-Rouse Correlation Cathcart-Pawel Uncertainty Multiplier CR 2012-8277 0 2012 Equation S-RELAP5 Routine with RODEX3 CR 2013-4230 -10 2013 Fuel Model S-RELAP5 vapor absorptivity CR 2012-8371 0 2014 correlation Non-physical axial shapes generated CR 2014-3953 0 2014 by the modal decomposition procedure Error in Application of Power Cutback CR 2015-6562 0 2015 Ratios for Once-Burned Gadolinia Bearing Rods Estimate for model inclusion with Inclusion of a updates for CR 2017-3565, Swell and Rupture +31 2018 Updated M5 SRM, and Model CR 2017-5630, Metal-water reaction error.

Total Delta +35 Total 2119

PCT Trace 2000 G:'

"; 1500

~Q)

CL 1: *

~

7ii 1000 Q)

i:

500 0 '--'--~--'--~~~-~~-~_.____,_--~~-~

0 50 100 150 200 250 300 Tlme(s)

Figure A-1 S&R Case: Limiting Rod Peak Clad Temperature

Cladding Temperatures 2000 1500 1000 500

-

• Hot Assembly, Node 34

• Fresh 8%, Node 34 0 ~---'-----'10----L....c._----'

0 20

---

'-~"--'---~-___._____,

30 40 50 60 Time(s)

Figure A-2 S&R Case: Nodal Cladding Temperatures