ML19309D197

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Proposed License Amendment Request Addition of Analytical Methodology to the Core Operating Limits Report for a Full Spectrum Loss of Coolant Accident
ML19309D197
Person / Time
Site: North Anna  Dominion icon.png
Issue date: 10/30/2019
From: Mark D. Sartain
Virginia Electric & Power Co (VEPCO)
To:
Document Control Desk, Office of Nuclear Reactor Regulation
References
19-242
Download: ML19309D197 (50)


Text

VIRGINIA ELECTRIC AND POWER COMPANY RICHMOND, VIRGINIA 23261 October 30, 2019 10 CFR 50.90 United States Nuclear_ Regulatory Commission Serial No.: 19-242 Attention: Document Control Desk NRA/DEA: RO Washington, D.C. 20555-0001 Docket Nos.: 50-338/339 License Nos.: NPF-4/7 VIRGINIA ELECTRIC AND POWER COMPANY NORTH ANNA POWER STATION UNITS 1 AND 2 PROPOSED LICENSE AMENDMENT REQUEST ADDITION OF ANALYTICAL METHODOLOGY TO THE CORE OPERATING LIMITS REPORT FOR A FULL SPECTRUM LOSS OF COOLANT ACCIDENT (FSLOCA)

Pursuant to 10 CFR 50.90, Virginia Electric and Power Company (Dominion Energy Virginia) is submitting a request for an amendment to revise the Technical Specifications (TS) for North Anna Power Station (NAPS) Units 1 and 2. The proposed amendment requests the addition of the Westinghouse Topical Report WCAP-16996-P-A, "Realistic LOCA Evaluation Methodology Applied to the Full Spectrum of Break Sizes (FULL SPECTRUM LOCA Methodology)," to the list of approved analytical methods used to determine the core operating limits as listed in TS 5.6.5, "Core Operating Limits Report (COLR)."

Supporting information is provided in the attachments to this letter as summarized below:

  • Attachment 1 provides an evaluation of the proposed TS change
  • Attachment 2 provides marked-up TS pages
  • Attachment 3 provides proposed TS pages
  • Attachment 4 provides a technical evaluation of the proposed change Dominion Energy Virginia has evaluated the proposed amendment and determined that it does not involve a significant hazards consideration as defined in 10 CFR 50.92. The basis for this determination is included in Attachment 1. Dominion Energy Virginia has also determined that operation with the proposed change will not result in any significant increase in the amount of effluents that may be released offsite or any significant increase in individual or cumulative occupational radiation exposure. Therefore, the proposed amendment is eligible for categorical exclusion from an environmental assessment as set forth in 10 CFR 51.22(c)(9). Pursuant to 10 CFR 51.22(b), no environmental impact statement or environmental assessment is needed in connection with the approval of the proposed change.

The proposed TS change has been reviewed and approved by the NAPS Facility Safety Review Committee.

Serial No.19-242 Docket Nos. 50-338/339 LAR - Addition of Methodology to COLR for FSLOCA Page 2 of 3 Dominion Energy Virginia requests approval of the proposed amendment by October 31, 2020, with a 90-day implementation period.

If there are any questions or if additional information is needed, please contact Ms.

Diane Aitken at (804 )-273-2694.

Sincerely, Mark D. Sartain Vice President - Nuclear Engineering and Fleet Support COMMONWEAL TH OF VIRGINIA COUNTY OF HENRICO The foregoing document was acknowledged before me, in and for the County and Commonwealth aforesaid, today by Mark D. Sartain, who is Vice President - Nuclear Engineering and Fleet Support of Virginia Electric and Power Company. He has affirmed before me that he is duly authorized to execute and file the foregoing document in behalf of that Company, and that the statements in the document are true to the best of his knowledge and belief.

Acknowledged before me this ~O~ day of 0c.,.,..\o~ ,2019.

My Commission Expires: Ou~~\ 1 -Z..c,Z....3.

Commitments made in this letter: None Attachments:

1. Discussion of the Proposed Change
2. Marked-up Technical Specifications Pages
3. Proposed Technical Specifications Pages
4. Technical Evaluation -Application of Westinghouse Full Spectrum LOCA Evaluation Model to North Anna Power Station Units 1 and 2

Serial No.19-242 Docket Nos. 50-338/339 LAR - Addition of Methodology to COLR for FSLOCA Page 3 of 3 cc: U.S. Nuclear Regulatory Commission, Region II Marquis One Tower 245 Peachtree Center Avenue, NE Suite 1200 Atlanta, Georgia 30303-1257 NRC Senior Resident Inspector North Anna Power Station Mr. Vaughn Thomas NRC Project Manager U. S. Nuclear Regulatory Commission One White Flint North Mail Stop 04 F-12 11555 Rockville Pike Rockville, Maryland 20852-2738 Mr. G. Edward Miller NRC Senior Project Manager U. S. Nuclear Regulatory Commission One White Flint North Mail 0-9E3 11555 Rockville Pike Rockville, Maryland 20852-2738 Mr. Marcus Harris Old Dominion Electric Cooperative Innsbrook Corporate Center, Suite 300 4201 Dominion Blvd.

Glen Allen, Virginia 23060 State Health Commissioner Virginia Department of Health James Madison Building - 7th Floor 109 Governor Street Room 730 Richmond, Virginia 23219

Attachment 1 DISCUSSION OF THE PROPOSED CHANGE Virginia Electric and Power Company (Dominion Energy Virginia)

North Anna Power Sta'tion Units 1 and 2

Serial No.19-242 Docket Nos. 50-338/339 LAR - Addition of Methodology to COLR for FSLOCA Page 1 of 6 DISCUSSION OF THE PROPOSED CHANGE NORTH ANNA POWER STATION UNITS 1 AND 2 1.0

SUMMARY

DESCRIPTION Virginia Electric and Power Company (Dominion Energy Virginia) proposes this license amendment request (LAR) to Facility Operating License Numbers NPF-4 and NPF-7 for North Anna Power Station (North Anna) Units 1 and 2, respectively.

The proposed Technical Specification (TS) change adds the Westinghouse Topical Report WCAP-16996-P-A, "Realistic LOCA Evaluation Methodology Applied to the Full Spectrum of Break Sizes (FULL SPECTRUM LOCA Methodology),"

[Reference 1] to the list of methodologies approved for use in determining core operating limits in Technical Specification 5.6.5, "Core Operating Limits Report (COLR)." The added methodology identifies the analytical methods used to determine core operating limits for the Large Break Loss of Coolant Accident (LBLOCA) event described in the North Anna Power Station Updated Final Safety Analysis Report (UFSAR), Section 15.4.1. In addition, legacy methods in TS 5.6.5 that are no longer required to support North Anna reload cores will be removed. .i An LBLOCA analysis has been completed for North Anna Units 1 and 2 with the Westinghouse FULL SPECTRUM LOCA (FSLOCA) Methodology, [Reference 1].

The analysis was performed in compliance with all the NRC conditions and limitations as identified in WCAP-16996-P-A, Revision 1. Based on the analysis results, it is concluded that North Anna Units 1 and 2 continue to maintain a margin of safety to the limits required by 10 CFR 50.46.

The Westinghouse FSLOCA Evaluation Model (EM) has been approved* by the Nuclear Regulatory Commission (NRC) for Westinghouse 3-loop and 4-loop plants with cold leg Emergency Core Cooling System (ECCS) injection [SER included in Reference 1]. Since North Anna Units 1 and 2 are Westinghouse designed 3-loop plants with cold leg ECCS injection, this approved analytical method is applicable.

The proposed LAR has been reviewed, and it has been determined that no significant hazards consideration exists as defined in 10 CFR 50.92. In addition, it has been determined that the change qualifies for categorical exclusion from an environmental assessment as set forth in 10 CFR 51.22(c)(9); therefore, no environmental impact statement or environmental assessment is needed in connection with the approval of the proposed TS change.

Serial No.19-242 Docket Nos. 50-338/339 LAR - Addition of Methodology to COLR for FSLOCA Page 2 of 6 2.0 DETAILED DESCRIPTION 2.1. System Design and Operation The design requirements of existing plant systems, structures, and components (SSCs) are used as inputs to the LBLOCA analysis, with appropriate technical conservatisms applied. Therefore, the LBLOCA analysis does not directly impact the existing design or configuration of any plant SSCs.

2.2. Current Technical Specification R~quirements TS 5.6.5 directs that core operating limits shall be established prior to each reload cycle and contains references to the approved analytical methods that are used to determine the core operating limits. The current method listed for an LBLOCA analysis is the Westinghouse Automated Statistical Treatment of Uncertainty Method (ASTRUM) EM identified in Reference 2 of TS 5.6.5.

2.3. Reason for the Proposed Change By letter dated May 6, 2016 [Reference 2], Dominion Energy Virginia committed to submit a LBLOCA analysis that applies NRG-approved methods that include the effects of fuel pellet thermal conductivity degradation (TCD) to the NRC for review and approval by June 30, 2019. The Westinghouse FSLOCA EM includes the effects of TCD, and this LAR is being submitted to fulfill the commitment. The commitment date provided in Reference 2 was later changed to October 31, 2019 by letter dated June 26, 2019 [Reference 4].

2.4. Description of Proposed Change Mark-ups of the following changes to TS 5.6.5b are included in Attachment 2 and the proposed changes to TS 5.6.5b are included in Attachment 3:

TS 5.6.5b currently includes approved analytical methods that are no longer used to support North Anna reload cores. The proposed revision will remove the following legacy analytical methods listed in TS 5.6.5b:

10. BAW-10227P-A, "Evaluation of Advanced Cladding and Structural Material (M5) in PWR Reactor Fuel."
11. BAW-10199P-A, "The BWU Critical Heat Flux Correlations."
12. BAW-10170P-A, "Statistical Core Design for Mixing Vane Cores."

Serial No.19-242 Docket Nos. 50-338/339 LAR - Addition of Methodology to COLR for FSLOCA Page 3 of 6

13. EMF-2103 (P) (A), "Realistic Large Break LOCA Methodology for Pressurized Water Reactors."
14. EMF-96-029(P)(A), "Reactor Analysis System for PWRs."
16. [Appendix A of DOM-NAF-2-A], "Qualification of the F-ANP BWU CHF Correlations in the Dominion VIPRE:..D Computer Code."

Method 2, "(WCAP-16009-P-A, "Realistic Large Break LOCA Evaluation Methodology Using the Automated Statistical Treatment of Uncertainty Method (ASTRUM))," is being retained in TS 5.6.5b. This allows for an orderly transition to FSLOCA with PAD5 in a subsequent reload cycle, recognizing that the TS are applicable to both Units 1 and 2.

The proposed revision adds WCAP-16996-P-A to the list of approved methods.

The proposed change is as follows:

  1. . WCAP-16996-P-A, "Realistic LOCA Evaluation Methodology Applied to the Full Spectrum of Break Sizes (FULL SPECTRUM LOCA Methodology)," (Westinghouse Proprietary).

3.0 TECHNICAL EVALUATION

Attachment 4, "Technical Evaluation - Application of Westinghouse Full Spectrum LOCA Evaluation Model to North Anna Power Station Units 1 and 2," provides the technical evaluation for the application of the Westinghouse FSLOCA EM to North Anna. This evaluation was performed in accordance with the NRG-approved FSLOCA EM in Westinghouse Topical Report WCAP-16996-P-A. The application of this Topical Report to North Anna involves only the analysis for Region II (LBLOCA), as discussed in Section 1.0 of Attachment 4 (Technical Evaluation).

This application is a replacement 'for the existing ASTRUM LBLOCA analysis, which addresses breaks from 1.0 ft2 to two times the area of-the RCS cold leg piping.

The small break LOCA (SBLOCA) portion of the break spectrum is currently addressed for North Anna Units 1 and 2 using the NOTRUMP EM methodology (Methods 3 and 4 in the TS 5.6.5b list).

The removal of unused legacy methods will have no technical impact on the ability to meet COLR limits.

Serial No.19-242 Docket Nos. 50-338/339 LAR - Addition of Methodology to COLR for FSLOCA Page 4 of 6

4.0 REGULATORY EVALUATION

4.1. Applicable Regulatory Requirements and Criteria The FSLOCA EM in WCAP-16996-P-A satisfies the requirements of 10 CFR 50.46(b) paragraphs (1) through (4). The proposed change meets the current regulatory requirements and does not affect conformance with the General Design Criteria as described in the North Anna Units 1 and 2 UFSAR.

Conformance with General Design Criterion 35, "Emergency Core Cooling," is described in more detail in Reference 1.

4.2. Precedents The proposed change to TS 5.6.5 adds Westinghouse Topical Report WCAP-16996-P-A to the list of approved methodologies for determining core operating limits at North Anna. Numerous previous requests have been approved for the

. addition of an approved analytical method used to determine the core operating limits to* the plant specific list of methods in TS 5.6.5b. The NRC has not previously approved the addition of WCAP-16996-P-A to the list of approved methodologies for determining core operating limits for other plants. A LAR requesting this change has been submitted for Diablo Canyon Units 1 and 2 (Reference 3).

4.3. No Significant Hazards Consideration The proposed change to Technical Specification (TS) 5.6.5 adds Westinghouse Topical Report WCAP-16996-P-A to the list of approved methodologies for use in determining core operating limits. The proposed change also removes obsolete methodologies. ,

Dominion Energy Virginia has evalu*ated whether a significant hazards consideration is involved with the proposed amendment by focusing on the three standards set forth in 10 CFR 50.92, ."Issuance of Amendment," as discussed below:

1. Does the proposed change involve a significant increase in the probability or consequences of an accident previously evaluated?

Response: No.

The proposed .change to TS 5.6..5 permits the use of an NRG-approved methodology for analysis of the LBLOCA to determine if North Anna Units 1 and 2, continue to meet the applicable design and safety analysis

Serial No.19-242 Docket Nos. 50-338/339 LAR - Addition of Methodology to COLR for FSLOCA Page 5 of 6 acceptance criteria. The proposed change to the list of NRG-approved methodologies in TS 5.6.5 has no direct impact upon plant operation or configuration. The list of methodologies in TS 5.6.5 does not impact either the probability of the initiation of an accident previously evaluated or its consequences.

The results of the LBLOCA analysis demonstrate North Anna continues to satisfy the 10 CFR 50.46(b)(1-4) ECCS performance acceptance criteria using an NRG-approved evaluation model.

Therefore, the proposed change does not involve a significant increase in*

the probability or consequences of an accident previously evaluated.

2. Does the proposed change create the possibility of a new or different kind of accident from any accident previously evaluated?

Response: No.

The proposed change will not create the possibility of a new or different accident due to credible new failure mechanisms, malfunctions, or accident initiators not previously considered. There is no change to the parameters within which the plant is normally operated and no physical plant modifications are being made; thus, the possibility of a new or different type of accident is not created.

Therefore, the proposed change does not create the possibility of a new or different kind of accident or malfunction from those previously evaluated in the UFSAR.

3. Does the proposed change involve a significant reduction in a margin of safety?

Response: No.

No design basis safety limits are exceeded or altered by this change.

Approved methodologies will be used to ensure that the plant continues to meet applicable design criteria and safety analysis acceptance criteria.

Therefore, the proposed change does not involve a significant reduction in a margin of safety.

Based on the above information, Dominion Energy Virginia concludes that the proposed change does not involve a significant hazards consideration under the standards set forth in 10 CFR 50.92(c), and, accordingly, a finding of "no significant hazards consideration" is justified.

Serial No.19-242 Docket Nos. 50-338/339 LAR - Addition of Methodology to COLR for FSLOCA Page 6 of 6 4.4. Conclusion Based on the considerations presented above, there is reasonable assurance that (1) the health and safety of the public will not be endangered by the demonstration that North Anna Units 1 and 2 continue to meet applicable design criteria and safety analysis acceptance criteria, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the requested license amendment will not be inimical to the common defense and security or to the health and safety of the public.

5.0 Environmental Considerations Dominion Energy Virginia has reviewed the proposed license amendment for environmental considerations in accordance with 10 CFR 51.22. The proposed license amendment does not involve (i) a significant hazards consideration, (ii) a significant change in the types or significant increase in the amounts of any effluent that may be released offsite, or (iii) a significant increase in individual or cumulative occupational radiation exposure. Accordingly, the proposed amendment meets the eligibility criterion for categorical exclusion from an environmental assessment as set forth in 10 CFR 51.22(c)(9). Therefore, pursuant to 10 CFR 51.22(b), no environmental impact statement or environmental assessment need be prepared in connection with the proposed amendment.

6.0 References

1. Westinghouse Topical Report WCAP-16996-P-A, Revision 1, "Realistic LOCA Evaluation Methodology Applied to the Full Spectrum of Break Sizes (FULL SPECTRUM LOCA Methodology)," November 2016.
2. Letter from M. D. Sartain (Dominion) to USNRC (Serial No.16-174), "Virginia Electric and Power Company, North Anna Power Station Units 1 and 2, 30-Day Report of Emergency Core Cooling System (ECCS) Model Changes Pursuant to the Requirements of 10 CFR 50.46," May 6, 2016 (ADAMS Accession Number ML16134A071).
3. Letter from Paula Gerfen (PG&E) to USNRC (DCL No.18-100), "License Amendment Request 18-02, License Amendment Request to Revise Technical Specification 5.6.5b, 'Core Operating Limits Report (COLR)' for Full Spectrum Loss-of-Coolant Accident Methodology," December 26, 2019 (ADAMS Accession Number ML19003A196).*

Attachment 2 MARKED-UP TECHNICAL SPECIFICATIONS PAGES Virginia Electric and Power Company (Dominion Energy Virginia)

North Anna Power Station Units 1 and 2

Serial No.19-242 Docket No. 50-280/281 LAR - Addition of FSLOCA Methodology to COLR Repor t i R u; re nt s 5.6 5.6 Repo

  • ts 5,.6.5 C(R[ <J>[RATING LI ITS R£P<ltT (CO Rl (cont inued)
b. The anal ytical t hods used to detenii ne the core operati no Ii i ts shall be those previ ous l y reviewed and appr oved by the RC , specificall y those descri i n the fol I ing d.oc r.ts:
1. V[P- FR0-42-A , *Relo ad Nucl ear Des ign thodology. *
2. Pl an t-s pec ific ad tati on of P-1600,.P-A. '" ali sti c Large 8rt>a LOCA [ v l t ion Net hodolo si ng the Aut 0111ated Statistical Trea t of Unce rta i nty thod (AS ) ,* as approved by N C Safe ty [ val u tion ort dat ed f ru ary 29, 2012 .
3. AP- 1 -P- ,
  • sti nghouse 11 Brea [ CCS [ val uation e l Us i ng t he NOT Code. *
4. P-10079-P-A , *NOTRU P. A Nodal T 1nsient Sma ll Brea anod Gener al two rk Code . *
5. P- 12610, "YA NrAG[t run ASS U-R[f CE CORE RCPORT. *
6. [ P-N[ A, Stati s tical DNSR [ val uatiCM1 e t hodol ogy . *
7. r[ P-N[ A, V£PCO Rel axed Pow.- Distributioo Cont r ol t hodol ogy and Associated rQ Surve i l l ance Techn ical Specifications . '"
8. AP-8745-P- A, i>esign Bases for Th I Ow*e r Delta -T and The al Overt rature Del t a-IT ip runction.
9. AP- 1448 3-A , *Generic t hodol ogy fo Expanded Co.-e Operati ng Li its Report .
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Serial No.19-242 Docket No. 50-280/281 LAR - Addition of FSLOCA Methodology to COLR rtino ReQuir n s

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5. 6 Repo rt ing Requi r<<r.erit s 5.6.5 COR[ 0 [RATING LI ITS R~PORT {CO I) (cort *nued)
b. (continued)
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5. BAW-10168 - , RS6 01:A - 8W Loss-of -Coohnt Acci de t Eva luati on lllo!lel or eci rcu l atinJ s earn Generator Pl a11ts. "

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Figure 1: North Anna Units 1 and 2 Peak Cladding Temperature for all Rods for the Region II Analysis PCT Case Assuming LOOP Page 19 of 33

Serial No.19-242 Westinghouse Non-Proprietary Class 3 Docket Nos. 50-338/339 PCT-LOC 6 0 0 PEAK CLAD TE MP LOC, 10 8

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Figure 2: North Anna Units 1 and 2 Peak Cladding Temperature Elevation Relative to the Bottom of the Active Fuel for the Region II Analysis PCT Case Assuming LOOP Page 20 of 33

Serial No.19-242 Westinghouse Non-Proprietary Class 3 Docket Nos. 50-338/339 MTH00179 37 0 Break Fl ow 80000 soooo- .

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Figure 4: North Anna Units 1 and 2 Lower Plenum Collapsed Liquid Level Relative to the Inner Bottom of the Vessel for the Region II Analysis PCT Case Assuming LOOP Page 22 of 33

Serial No.19-242 Westinghouse Non-Proprietary Class 3 Docket Nos. 50-338/339 FGM 11 1 0 Bottom Cel I FGM 11 15 0 Top Cell 1500 1000 ,,

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Figure 5: North Anna Units 1 and 2 Vapor Mass Flow Rate at the Top and Bottom Cell Faces of the Core Average Channel not Under Guide Tubes for the Region II Analysis PCT Case Assuming LOOP Page 23 of 33

Serial No.19-242 Westinghouse Non-Proprietary Class 3 Docket Nos. 50-338/339 FLM 11 1 0 Bo t tom Ce l I FLM 11 15 0 Top Ce ll 5000- I* . . .* . . . . .. . ..... . . . ... . ...........*.. . .*... ... . ...... . ....

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Serial No.19-242 Westinghouse Non-Proprietary Class 3 Docket Nos. 50-338/339 PN 29 0 PRESSURE

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Figure 7: North Anna Units 1 and 2 RCS Pressure for the Region II Analysis PCT Case Assuming LOOP Page 25 of 33

Serial No.19-242 Westinghouse Non-Proprietary Class 3 Docket Nos. 50-338/339 f.4 T H00189 64 9 0 Component 64 MTH00 191 74 9 0 Component 74

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Figure 8: North Anna Units 1 and 2 Accumulator Injection Flow per Loop for the Region II Analysis PCT Case Assuming LOOP Page 26 of 33

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Figure 9: North Anna Units 1 and 2 Containment Pressure for the Region II Analysis PCT Case Assuming LOOP Page 27 of 33

Serial No.19-242 Westinghouse Non-Proprietary Class 3 Docket Nos. 50-338/339 VFMASS 0 0 0 VESSEL WA TER MA SS 140000 120000 100000 E

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0 100 200 300 400 500 600 700 Time After Break (sec) 14.311414243 Figure 10: North Anna Units 1 and 2 Vessel Fluid Mass for the Region II Analysis PCT Case Assuming LOOP Page 28 of 33

Serial No.19-242 Westinghouse Non-Proprietary Class 3 Docket Nos. 50-338/339 LQ- LEVE L 5 0 0 Hot Assembly Channel LQ-L EVE L 3 0 0 Non - GT Avg Channe l LQ -L EVE L 4 0 0 GT Avg Channe l LQ- LEVE L 2 0 0 l ow Power Channe l 10

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Figure 11: North Anna Units 1 and 2 Collapsed Liquid Level for Each Core Channel Relative to the Bottom of the Active Fuel for the Region II Analysis PCT Case Assuming LOOP Page 29 of 33

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Figure 12: North Anna Units 1 and 2 Average Downcomer Collapsed Liquid Level Relative to the Bottom of the Upper Tie Plate for the Region II Analysis PCT Case Assuming LOOP Page 30 of 33

Serial No.19-242 Westinghouse Non-Proprietary Class 3 Docket Nos. 50-338/339 MTH00183 15 6 0 Loop 1 SI MTH00185 25 6 0 Loop 2 SI

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' '--i 0 100 200 300 400 500 600 700 Time After Break (sec)

Figure 13: North Anna Units 1 and 2 Total Safety Injection Flow Rate per Loop (not including Accumulator Flow) for the Region II Analysis PCT Case Assuming LOOP Page 31 of 33

Serial No.19-242 Westinghouse Non-Proprietary Class 3 Docket Nos. 50-338/339 Hot Rod Hot Assembly Rod Average Rod 2.5....---------------------------------,

2.0 Q) 3 1,5 0

a..

-0 OJ C

E 0

z 1.0 Q.5 o.o 0 2 4 6 8 10 12 Elevation (ft) 413927354 Figure 14: North Anna Units 1 and 2 Normalized Rod Axial Power Shapes for the Region II Analysis PCT Case Assuming LOOP Note: The localized power decreases occur at grid elevations. Page 32 of 33

Serial No.19-242 Westinghouse Non-Proprietary Class 3 Docket Nos. 50-338/339 POWERF 0 0 0 RELATIVE CORE PO WER 1.2 1-

~

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C o.a-I-

0 z

0 C

0 f-u 0.6-0 LL.. I-

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0 CL Q) 0.4-0 f-u f-0.2-I I I I I I I I I I I I I I I I I I I I I I I I I I I I 0 I 0 100 200 300 400 500 600 700 1740612692 Figure 15: North Anna Units 1 and 2 Relative Core Power for the Region II Analysis PCT Case Assuming LOOP Page 33 of 33