ML18194A947
| ML18194A947 | |
| Person / Time | |
|---|---|
| Site: | NuScale |
| Issue date: | 07/13/2018 |
| From: | Rad Z NuScale |
| To: | Document Control Desk, Office of New Reactors |
| Shared Package | |
| ML18194A946 | List: |
| References | |
| AF-0718-60887, RAIO-0718-60857 | |
| Download: ML18194A947 (22) | |
Text
RAIO-0718-60857 July 13, 2018 Docket No.52-048 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk One White Flint North 11555 Rockville Pike Rockville, MD 20852-2738
SUBJECT:
NuScale Power, LLC Response to NRC Request for Additional Information No.
440 (eRAI No. 9487) on the NuScale Design Certification Application
REFERENCE:
U.S. Nuclear Regulatory Commission, "Request for Additional Information No.
440 (eRAI No. 9487)," dated April 30, 2018 The purpose of this letter is to provide the NuScale Power, LLC (NuScale) response to the referenced NRC Request for Additional Information (RAI).
The Enclosures to this letter contain NuScale's response to the following RAI Question from NRC eRAI No. 9487:
15-5 is the proprietary version of the NuScale Response to NRC RAI No. 440 (eRAI No.
9487). NuScale requests that the proprietary version be withheld from public disclosure in accordance with the requirements of 10 CFR § 2.390. The enclosed affidavit (Enclosure 3) supports this request. Enclosure 2 is the nonproprietary version of the NuScale response.
This letter and the enclosed responses make no new regulatory commitments and no revisions to any existing regulatory commitments.
If you have any questions on this response, please contact Paul Infanger at 541-452-7351 or at pinfanger@nuscalepower.com.
Sincerely, Zackary W. Rad Director, Di t Regulatory R l t Affairs Aff i NuScale Power, LLC Distribution: Gregory Cranston, NRC, OWFN-8G9A Samuel Lee, NRC, OWFN-8G9A Rani Franovich, NRC, OWFN-8G9A NuScale Power, LLC 1100 NE Circle Blvd., Suite 200 Corvalis, Oregon 97330, Office: 541.360.0500, Fax: 541.207.3928 www.nuscalepower.com
RAIO-0718-60857 : NuScale Response to NRC Request for Additional Information eRAI No. 9487,
proprietary : NuScale Response to NRC Request for Additional Information eRAI No. 9487, nonproprietary : Affidavit of Zackary W. Rad, AF-0718-60887 NuScale Power, LLC 1100 NE Circle Blvd., Suite 200 Corvalis, Oregon 97330, Office: 541.360.0500, Fax: 541.207.3928 www.nuscalepower.com
NuScale Response to NRC Request for Additional Information eRAI No. 9487, proprietary NuScale Power, LLC 1100 NE Circle Blvd., Suite 200 Corvalis, Oregon 97330, Office: 541.360.0500, Fax: 541.207.3928 www.nuscalepower.com
NuScale Response to NRC Request for Additional Information eRAI No. 9487, nonproprietary NuScale Power, LLC 1100 NE Circle Blvd., Suite 200 Corvalis, Oregon 97330, Office: 541.360.0500, Fax: 541.207.3928 www.nuscalepower.com
Response to Request for Additional Information Docket No.52-048 eRAI No.: 9487 Date of RAI Issue: 04/30/2018 NRC Question No.: 15-5 Title 10 of the Code of Federal Regulations (10 CFR) Part 52, Section 47 require a final safety analysis report (FSAR) to analyze the design and performance of the structures, systems, and components (SSCs). Safety evaluations, performed to support the FSAR, include accident analyses to (1) demonstrate that specified acceptable fuel design limits (SAFDLs) are not exceeded during normal operation, including the effects of anticipated operational occurrences (AOOs), and (2) determine the number of fuel failures associated with critical heat flux (CHF) that need to be included in the radiological consequences for postulated accidents.
As the return to power analysis in FSAR 15.0.6 can occur, assuming a stuck rod, within a few hours from either an AOO or postulated accident initiating event, the AOO acceptance criteria of General Design Criterion (GDC) 10 applies. GDC 10, Reactor design, requires that the reactor core and associated coolant, control, and protection systems be designed with appropriate margin to assure that SAFDLs are not exceeded during any condition of normal operation, including the effects of AOOs.
The LOCA NRELAP5 model uses a bottom skewed axial power shape to evaluate minimum critical heat flux ratio (MCHFR). The staff notes the hot channel axial power shape would likely be top peaked in the return to power analysis (calculated in EE-0000-4820 to support FSAR 15.0.6) in the stuck rod location. A top peaked axial power shape in the hot channel is usually more limiting when evaluating the MCHFR. The staff is requesting that the applicant evaluate the potential change in MCHFR with an axial shape representing the worst rod stuck out, or provide justification for the assumed power shape so that the staff can confirm the analysis conditions are appropriate.
NuScale Response:
Sensitivity to axial power shape is evaluated for the FSAR Section 15.0.6 minimum critical heat
flux ratio (MCHFR) case using ((2(a),(c) of TR-0516-49422, Revision 0 Loss-of-Coolant Accident Evaluation Model. It is noted that the severity of the results increased in some part due to an error in the implementation of the maximum radial peaking factor in the original analysis that has now been corrected. A NuScale Nonproprietary
spectrum of ECCS timings was also evaluated for each power shape, as described in RAI-9489, Question 15-20, letter number RAIO-0718-60858, dated July 13, 2018, which justifies applying the ECCS actuation coincident with the timing of the peak power. Axial power shape sensitivity results are given in Table 1. ((
}}2(a),(c)
From the above results, it is observed that a top peak axial power shape provides a higher core power response and the limiting MCHFR value. Therefore, FSAR Section 15.0.6 results are updated to reflect a top peaked axial power shape as limiting for MCHFR per the attached markup. All acceptance criteria remain satisfied for the analysis. Impact on DCA: FSAR Section 15.0.6 and associated figures 15.0-8, 15.0 15.0-19 have been revised as described in the response above and as shown in the markup provided with this response. NuScale Nonproprietary
NuScale Final Safety Analysis Report Transient and Accident Analyses For the limiting MCHFR portion of the analysis, a loss of highly reliable DC power (EDSS) is assumed at the time of DHRS initiation, resulting in ECCS actuation. The timing of the ECCS valve opening is near the power peak as determined by a timing sensitivity analysis. The following conservatisms are applied to the MCHFR portion of the analysis: RAI 15-1
- IAB release timing is sequenced with the timing of the power peak in order to evaluate the most limiting ECCS transition event sequence.
RAI 15-1
- The maximum radial peaking (F'h) due to the stuck control rod is 6.5. The return to power is driven by the lack of necessary negative reactivity insertion due to the postulated most reactive control rod stuck in a fully withdrawn position. The critical power will be localized in this location generating higher than normal radial peaking.
RAI 15-1, RAI 15-5
- The bottomtop shaped axial power distribution is applied consistent with the LOCA EM.
RAI 15-1
- The ECCS valve characteristics are conservatively set to maximize the depressurization effect on MCHFR.
RAI 15-1, RAI 15-5
- Uniform radial and axial density reactivity feedback is used to conservatively bound the localized reactivity suppression due to the localized power generated around the stuck rod location. Flux squared density reactivity feedback weighting is used axially.
RAI 15-1 15.0.6.3.3 Results The sequence of events for the DHRS overcooling event is provided in Table 15.0-16. Figure 15.0-8 provides the power response on the return to power. Figure 15.0-10 through Figure 15.0-13 show the transient behavior of key parameters. RAI 15-1 The overcooling return to power event begins with an initial negative reactivity insertion that is gradually removed as the transient progresses until a return to power occurs (Figure 15.0-8 and Figure 15.0-10). The biased initial conditions, with increased heat transfer, and low pool temperature results in a slightly larger return to power. A sensitivity analysis on background decay heat shows a minor sensitivity, where higher decay heat results in a slightly slower event progression and marginally decreased peak power. Initial negative reactivity insertion also has little impact on the calculated peak power. Therefore, it is concluded that protection of shutdown margin is insignificant for this event. RAI 15-1 Tier 2 15.0-43 Draft Revision 2
NuScale Final Safety Analysis Report Transient and Accident Analyses RAI 15-1, RAI 15-5 Table 15.0-17: Sequence of Events for Overcooling Return to Power Event EDSS unavailable (MCHFR Case) Event Time [s]* Time of power peak 77267897 Time of IAB release (ECCS actuation) 77297897 Time of minimum critical heat flux ratio 77337900 Note:
*Time is rounded.
Tier 2 15.0-74 Draft Revision 2
Tier 2 NuScale Final Safety Analysis Report RAI 15-5 Figure 15.0-8: Power Response on a Return to Power
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15.0-86
Transient and Accident Analyses
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Tier 2 NuScale Final Safety Analysis Report RAI 15-1, RAI 15-5 Figure 15.0-10: Return to Power - Net Reactivity (Peak Power Case)
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15.0-88
Transient and Accident Analyses
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Tier 2 NuScale Final Safety Analysis Report RAI 15-1, RAI 15-5 Figure 15.0-11: Return to Power - Average Reactor Coolant System Temperature (Peak Power Case)
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15.0-89
Transient and Accident Analyses
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Tier 2 NuScale Final Safety Analysis Report RAI 15-1, RAI 15-5 Figure 15.0-12: Return to Power - Volume Average Fuel Temperature (Peak Power Case)
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15.0-90
Transient and Accident Analyses
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Tier 2 NuScale Final Safety Analysis Report RAI 15-1, RAI 15-5 Figure 15.0-13: Return to Power - Reactor Pressure Vessel Lower Plenum Pressure (Peak Power Case)
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15.0-91
Transient and Accident Analyses
7LPH VHF Draft Revision 2
Tier 2 NuScale Final Safety Analysis Report RAI 15-1, RAI 15-5 Figure 15.0-14: Return to Power ECCS Transition Case - Critical Heat Flux Ratio (MCHFR Case)
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15.0-92
Transient and Accident Analyses
7LPH VHF Draft Revision 2
Tier 2 NuScale Final Safety Analysis Report RAI 15-1, RAI 15-5 Figure 15.0-15: Return to Power ECCS Transition Case - Reactor Power (MCHFR Case)
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15.0-93
Transient and Accident Analyses
7LPH VHF Draft Revision 2
Tier 2 NuScale Final Safety Analysis Report RAI 15-1, RAI 15-5 Figure 15.0-16: Return to Power ECCS Transition Case - RCS Flowrate (MCHFR Case)
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15.0-94
Transient and Accident Analyses
7LPH VHF Draft Revision 2
Tier 2 NuScale Final Safety Analysis Report RAI 15-1, RAI 15-5 Figure 15.0-17: Return to Power ECCS Transition Case - Hot Channel Heat Flux (MCHFR Case)
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15.0-95
Transient and Accident Analyses
7LPH VHF Draft Revision 2
Tier 2 NuScale Final Safety Analysis Report RAI 15-1S1, RAI 15-5 Figure 15.0-18: Reactor Power EDSS Available - Peak Power Case
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15.0-96
Transient and Accident Analyses
7LPH VHF Draft Revision 2
Tier 2 NuScale Final Safety Analysis Report RAI 15-1S1, RAI 15-5 Figure 15.0-19: RCS Flowrate (Peak Power Case EDSS Available)
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15.0-97
Transient and Accident Analyses
7LPH VHF Draft Revision 2
RAIO-0718-60857 : Affidavit of Zackary W. Rad, AF-0718-60887 NuScale Power, LLC 1100 NE Circle Blvd., Suite 200 Corvalis, Oregon 97330, Office: 541.360.0500, Fax: 541.207.3928 www.nuscalepower.com
NuScale Power, LLC AFFIDAVIT of Zackary W. Rad I, Zackary W. Rad, state as follows:
- 1. I am the Director, Regulatory Affairs of NuScale Power, LLC (NuScale), and as such, I have been specifically delegated the function of reviewing the information described in this Affidavit that NuScale seeks to have withheld from public disclosure, and am authorized to apply for its withholding on behalf of NuScale.
- 2. I am knowledgeable of the criteria and procedures used by NuScale in designating information as a trade secret, privileged, or as confidential commercial or financial information. This request to withhold information from public disclosure is driven by one or more of the following:
- a. The information requested to be withheld reveals distinguishing aspects of a process (or component, structure, tool, method, etc.) whose use by NuScale competitors, without a license from NuScale, would constitute a competitive economic disadvantage to NuScale.
- b. The information requested to be withheld consists of supporting data, including test data, relative to a process (or component, structure, tool, method, etc.), and the application of the data secures a competitive economic advantage, as described more fully in paragraph 3 of this Affidavit.
- c. Use by a competitor of the information requested to be withheld would reduce the competitor's expenditure of resources, or improve its competitive position, in the design, manufacture, shipment, installation, assurance of quality, or licensing of a similar product.
- d. The information requested to be withheld reveals cost or price information, production capabilities, budget levels, or commercial strategies of NuScale.
- e. The information requested to be withheld consists of patentable ideas.
- 3. Public disclosure of the information sought to be withheld is likely to cause substantial harm to NuScale's competitive position and foreclose or reduce the availability of profit-making opportunities. The accompanying Request for Additional Information response reveals distinguishing aspects about the process and method by which NuScale develops its safety analysis of the NuScale Power Module.
NuScale has performed significant research and evaluation to develop a basis for this process and method and has invested significant resources, including the expenditure of a considerable sum of money. The precise financial value of the information is difficult to quantify, but it is a key element of the design basis for a NuScale plant and, therefore, has substantial value to NuScale. If the information were disclosed to the public, NuScale's competitors would have access to the information without purchasing the right to use it or having been required to undertake a similar expenditure of resources. Such disclosure would constitute a misappropriation of NuScale's intellectual property, and would deprive NuScale of the opportunity to exercise its competitive advantage to seek an adequate return on its investment. AF-0718-60887
- 4. The information sought to be withheld is in the enclosed response to NRC Request for Additional Information RAI No. 440, eRAI No. 9487. The enclosure contains the designation "Proprietary" at the top of each page containing proprietary information. The information considered by NuScale to be proprietary is identified within double braces, "((
}}" in the document.
- 5. The basis for proposing that the information be withheld is that NuScale treats the information as a trade secret, privileged, or as confidential commercial or financial information. NuScale relies upon the exemption from disclosure set forth in the Freedom of Information Act ("FOIA"), 5 USC § 552(b)(4), as well as exemptions applicable to the NRC under 10 CFR §§ 2.390(a)(4) and 9.17(a)(4).
- 6. Pursuant to the provisions set forth in 10 CFR § 2.390(b)(4), the following is provided for consideration by the Commission in determining whether the information sought to be withheld from public disclosure should be withheld:
- a. The information sought to be withheld is owned and has been held in confidence by NuScale.
- b. The information is of a sort customarily held in confidence by NuScale and, to the best of my knowledge and belief, consistently has been held in confidence by NuScale.
The procedure for approval of external release of such information typically requires review by the staff manager, project manager, chief technology officer or other equivalent authority, or the manager of the cognizant marketing function (or his delegate), for technical content, competitive effect, and determination of the accuracy of the proprietary designation. Disclosures outside NuScale are limited to regulatory bodies, customers and potential customers and their agents, suppliers, licensees, and others with a legitimate need for the information, and then only in accordance with appropriate regulatory provisions or contractual agreements to maintain confidentiality.
- c. The information is being transmitted to and received by the NRC in confidence.
- d. No public disclosure of the information 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 contractual agreements that provide for maintenance of the information in confidence.
- e. Public disclosure of the information is likely to cause substantial harm to the competitive position of NuScale, taking into account the value of the information to NuScale, the amount of effort and money expended by NuScale in developing the information, and the difficulty others would have in acquiring or duplicating the information. The information sought to be withheld is part of NuScale's technology that provides NuScale with a competitive advantage over other firms in the industry.
NuScale has invested significant human and financial capital in developing this technology and NuScale believes it would be difficult for others to duplicate the technology without access to the information sought to be withheld. I declare under penalty of perjury that the foregoing is true and correct. Executed on July 13, 2018. Zackary W. Rad AF-0718-60887}}