SBK-L-15132, Response to Request for Additional Information for License Amendment Request 14-04 Revised Reactor Coolant System Pressure - Temperature Limits Applicable for 55 Effective Full Power Years

Response to Request for Additional Information for License Amendment Request 14-04 Revised Reactor Coolant System Pressure - Temperature Limits Applicable for 55 Effective Full Power Years

ML15194A042
Person / Time
Site:	Seabrook
Issue date:	07/09/2015
From:	Dodds R NextEra Energy Seabrook
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
SBK-L-15132
Download: ML15194A042 (15)

Text

NExTera ENERGY !

,,.,-ýSEýAB ROýOK July 9, 2015 10 CFR 50.90 SBK-L-15132 Docket No. 50-443 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001 Seabrook Station Response to Request for Additional Information for License Amendment Request 14-04 Revised Reactor Coolant System Pressure - Temperature Limits Applicable for 55 Effective Full Power Years

References:

1. Seabrook Station License Amendment Request 14-04, "Revised Reactor Coolant System Pressure - Temperature Limits Applicable for 55 Effective Full Power Years," SBK-L-14102, July 24, 2014 (ML14216A404).

2. NRC letter to Seabrook Station, "Seabrook Station, Unit No. 1 - Request for Additional Information Regarding License Amendment Request to Revise the Technical Specification Pressure-Temperature Limits and Request for Exemption from 10 CFR Part 50, Appendix G Minimum Temperature requirements (TAC Nos. MF4576 and MF4577)," dated January 9, 2015 (ML14363A367).

3. Seabrook Station letter SBK-L-15040, "Response to Request for Additional Information for License Amendment Request 14-04 Revised Reactor Coolant System Pressure -

Temperature Limits Applicable for 55 Effective Full Power Years, dated March 9, 2015 (ML15072A036).

4. Seabrook Station letter SBK-L-15129, "Response to Request for Additional Information for License Amendment Request 14-04 Revised Reactor Coolant System Pressure -

Temperature Limits Applicable for 55 Effective Full Power Years, dated June 23, 2015.

In Reference 1, NextEra Energy Seabrook, LLC (NextEra) submitted License Amendment Request (LAR) 14-04 to the Technical Specifications (TS) for Seabrook Station and requested an exemption from the requirements of 10 CFR 50 Appendix G. The proposed change revises the NextEra Energy Seabrook, LLC, P.O. Box 300, Lafayette Road, Seabrook, NH 03874

U.S. Nuclear Regulatory Commission SBK-L- 15132/Page 2 pressure-temperature (P/T) limits in TS 3 /4.4.9 LCO 3.4.9.1, Reactor Coolant System Pressure-Temperature Limits, to be applicable to 55 effective full power years. The change also revises TS 3 /4/4.9 LCO 3.4.9.3, Overpressure Protection Systems, by providing new overpressure protection setpoints and lowering the RCS temperature at which the TS is applicable.

In Reference 2, the NRC requested additional information to complete its review of LAR 14-04.

NextEra provided the responses to RAIs 2.1.1, 2.1.2, 2.1.3 and 2.1.4 in Reference 3 along with a request to extend its response to RAI 2.2.1 to June 30, 2015.

The response to RAI 2.2.1 required additional input from the vendor to complete the response.

In a conference call on June 17, 2015, the NRC requested an additional note be added to the Seabrook pressure-temperature curves restricting the heat-up rate to less than or equal to 20 'F per hour for moderator temperatures less than 120 'F. In Reference 4, NextEra requested additional time to obtain the requested information from its vendor, Westinghouse and to submit its response to RAI 2.2.1.

The response to RAI 2.2.1 is provided in the enclosure to this letter. The revised marked-up technical specification pages are provided in the attachment to this letter.

The response to the NRC RAI-2.2-1 resulted in a change to the previously submitted License Amendment Request 14-04 for the Seabrook Technical Specification (TS) 3.4.9.1, Pressure /

Temperature Limits, by providing new reactor coolant system (RCS) pressure and temperature (P/T) limits that are applicable to 55 effective full power years (EFPY). As a result, a No Significant Hazards Consideration was performed for the revised Pressure Temperature Limits in TS Figures 3.4-2 and 3.4-3.

This letter contains no regulatory commitments.

Should you have any questions regarding this letter, please contact Mr. Michael Ossing, Licensing Manager, at (603) 773-7512.

I declare under penalty of perjury that the foregoing is true and correct.

Executed on July _\ ,2015.

Sincerely, NextEra Energy Seabrook, LLC Ralph A. Dodds, III Plant General Manager Enclosure

U.S. Nuclear Regulatory Commission SBK-L-15132/Page 3 cc: D. Dorman, NRC Region I Administrator J. Lamb, NRC Project Manager, Project Directorate 1-2 P. Cataldo, NRC Senior Resident Inspector Mr. Perry Plummer Director Homeland Security and Emergency Management New Hampshire Department of Safety Division of Homeland Security and Emergency Management Bureau of Emergency Management 33 Hazen Drive Concord, NH 03305 John Giarrusso, Jr., Nuclear Preparedness Manager The Commonwealth of Massachusetts Emergency Management Agency 400 Worcester Road Framingham, MA 01702-5399

ENCLOSURE to SBK-L-15132 Response to Request for Additional Information for License Amendment Request 14-04 Revised Reactor Coolant System Pressure - Temperature Limits Applicable for 55 Effective Full Power Years

Response to Request for Additional Information for License Amendment Request 14-04 Revised Reactor Coolant System Pressure - Temperature Limits Applicable for 55 Effective Full Power Years NRC RAI2.2.1.: The current TS P-T limit curvesfor 23. 7 EFPY have margins to accountfor pressure and temperature instrument errors;the proposed 55 EFPY TS P-T limits do not have these margins.

Please address how instrumentationerrorswill be accountedfor to ensure that the RCS is operatedin accordancewith the proposed TS P-T limitsfor 55 EFPY NextEra Response:

The proposed TS P-T limit curves for 55 EFPY have been revised to include margins to account for pressure and temperature instrument uncertainty. Changes were also made to eliminate heat up and cool down rates that are not achievable during normal plant operating conditions in the lower temperature regions where the cold overpressure mitigation system (COMS) is enabled to protect the RCS with power operated relief valves (PORVs) as identified in TS Figure 3.4-4. No changes were made to the PORV set point values TS Figure 3.4-4 as this figure already contains appropriate instrument uncertainty as well as additional margins for pressure overshoot transients should an actuation occur.

Specifically, the revised curves shift the heat up and cool down P-T Limits curve data points developed in WCAP-17441-NP by 100 psi downward and 20'F to the right to account for the instrument uncertainty. An additional 15 psi uncertainty was applied to the heat up curve above the COMS enable temperature where operationally the wide range pressure indication on the main control board could be the only available indication in some unlikely but possible scenarios.

In addition to accounting for instrument uncertainty, unachievable heat up and cool down rates were eliminated or restricted.

For the heat up limitation curve, proposed TS Figure 3.4-2, a heat up rate restriction of 20°F/hr was added at temperatures at or below 120'F, corresponding to the transient defined in WCAP-17444 and the previous response to RAI 2.1.4. At temperatures greater than 120'F to less than 200'F the heat up rate of 80°F/hr maximum is specified and at greater than or equal to 200'F the maximum rate is 100°F/hr. Instrument uncertainties of 20'F and 100 psi were added to the data points in WCAP-17441-NP Table 6-3. An additional pressure uncertainty of 15 psi was added to the heat up curve starting at 200'F prior to the cold overpressure mitigation system being disabled. Considering the 20°F/hr rate restriction, pressure and temperature data from 60'F to 80'F (40°F to 60'F without the instrument uncertainty of 20'F) were determined using the more limiting pressure rate change between the existing 80°F/hr heat up data and the steady state data. Linear extrapolation of the 60'F to 65°F allowable pressure change of 13 psi per 5°F was applied to the heat up curve pressure limits from 60°F to 80'F.

These heat up rate limitations and instrument uncertainties additions result in all pressure limitations at or below 225°F, in the COMS enable temperature region, being above and protected by the COMS system set point curve in TS Figure 3.4-4.

For the cool down limitation curve, proposed TS Figure 3.4-3, the cool down rate is restricted to 20°F/hr at temperatures less than 150'F. Instrument uncertainties of 20'F and 100 psi were added to the data points in WCAP-17441-NP Table 6-4. Since the entire curve is to the left and above the COMS enable temperature and pressure limits identified in TS Figure 3.4-4, the additional 15 psi uncertainty was not Page 1 of 6

necessary. Pressure and temperature data from 60'F to 80'F (40'F to 60'F without the instrument uncertainty of 20'F) were determined by linear extrapolation of the pressure rate change between 60'F to 65'F for the 20°F/hr cool down data and the steady state data which results in a 13 psi change per 5°F. These cool down rate limitations and instrument uncertainties additions result in all pressure limitations being above and protected by the COMS system set point curve in TS Figure 3.4-4.

The bolt up temperature was maintained at 60'F as identified in WCAP-14040-A, Revision 4, "Methodology Used to Develop Cold Overpressure Mitigating System Setpoints and RCS Heatup and Cooldown Limit Curves." The limiting closure head region material RTndt is 30°F allowing bolt up temperature to be as low as 50'F with the application of uncertainty. However, the 60'F bolt up temperature advised in WCAP-14040-A is maintained.

The proposed heat up limitation curve, TS Figure 3.4-2, and the proposed cool down limitation curve, TS Figure 3.4-3 applicable for 55 EFPY have been revised to include margins to account for pressure and temperature instrument uncertainty as described above and are provided in the attachment. The revised data points for the revised heat up and cool down curves are provided in Tables 1 and 2 respectively.

Page 2 of 6

Significant Hazards Consideration No Significant Hazards Consideration:

The response to the NRC RAI-2.2-1 resulted in a change to the previously submitted License Amendment Request 14-04 for the Seabrook Technical Specification (TS) 3.4.9.1, Pressure /

Temperature Limits, by providing new reactor coolant system (RCS) pressure and temperature (P/T) limits that are applicable to 55 effective full power years (EFPY). As a result, a No Significant Hazards Consideration was performed for the revised Pressure Temperature Limits in TS Figures 3.4-2 and 3.4-3.

In accordance with 10 CFR 50.92, NextEra Energy Seabrook has concluded that the proposed change does not involve a significant hazards consideration (SHC). The basis for the conclusion that the proposed change does not involve a SHC is as follows:

1. Does the proposed change involve a significant increase in the probabilityor consequences of an accidentpreviously evaluated?

No. The proposed changes to the Technical Specifications (TS) do not impact the physical function of plant structures, systems, or components (SSCs) or the manner in which SSCs perform their design function. Operation in accordance with the proposed TS will ensure that all analyzed accidents will continue to be mitigated by the SSCs as previously analyzed. The proposed changes do not alter or prevent the ability of operable SSCs to perform their intended function to mitigate the consequences of an initiating event within assumed acceptance limits. The proposed changes neither adversely affect accident initiators or precursors, nor alter design assumptions.

Therefore, the proposed changes do 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 accidentfrom any previously evaluated?

No. The proposed changes do not involve installation of new or different type of equipment, create new failure modes for existing equipment, or create any new limiting single failures. The changes to the pressure - temperature limits will continue to ensure that appropriate fracture toughness margins are maintained to protect against reactor vessel failure, during both normal and low temperature operation.

The proposed changes are consistent with the applicable NRC approved methodologies (i.e., WCAP-14040, Rev. 4 and ASME Code Case N-641). Plant operation will not be altered, and all safety functions will continue to perform as previously assumed in accident analyses.

Therefore, the proposed changes do not create the possibility of a new or different kind of accident from any accident previously evaluated.

Page 3 of 6

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

No. Margin of safety is associated with confidence in the ability of the fission product barriers (i.e., fuel cladding, reactor coolant system pressure boundary, and containment structure) to limit the level of radiation dose to the public. The proposed changes will not adversely affect the operation of plant equipment or the function of any equipment assumed in the accident analysis. The proposed changes were developed using NRC approved methodologies and will continue to ensure an acceptable margin of safety is maintained. The safety analysis acceptance criteria are not affected by this change. The proposed changes will not result in plant operation in a configuration outside the design basis. The proposed changes do not adversely affect systems that respond to safely shutdown the plant and to maintain the plant in a safe shutdown condition.

Therefore, the proposed changes do not involve a significant reduction in a margin of safety.

Based on the above, NextEra concludes that the proposed amendment does not involve a significant hazards consideration under the standards set forth in 10 CFR 50.92(b), and, accordingly, a finding of "no significant hazards consideration" is justified.

Page 4 of 6

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Table 2 Data Points for the 55 EFPY Seabrook Unit 1 Cooldown Curves using the 1998 through the 2000 Addenda App. G Methodology (with Kic, without Flange Notch, and with Margins for Instrumentation Errors)

Steady-State 20 1F/hr Cooldown 100°F/hr Cooldown (00F/hr)

T P P P (OF) (psig) T ( 0F) (psig) T ( 0F) (psig) 60 0 60 0 60 577 60 537 65 590 65 550 70 603 70 563 75 616 75 576 80 629 80 589 85 642 85 602 90 656 90 618 95 671 95 635 100 689 100 654 105 708 105 674 110 729 110 697 115 752 115 723 120 778 120 751 125 806 125 782 130 838 130 817 135 872 135 855 140 911 140 897 145 953 145 944 150 1000 150 995 150 995 155 1052 155 1052 160 1109 160 1109 165 1172 165 1172 170 1242 170 1242 175 1319 175 1319 180 1404 180 1404 185 1499 185 1499 190 1603 190 1603 195 1718 195 1718 200 1846 200 1846 205 1986 205 1986 210 2142 210 2142 215 2314 215 2314 220 2504 1 220 2504 Page 6 of 6

Attachment to SBK-L- 15132 Marked-Up Technical Specification Pages

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Insert A MATERIAL PROPERTY BASIS LIMITING MATERIAL: Lower Shell Plate RI 808-1 without using surveillance data, Position 1.1 LIMITING ART VALUES AT 55 EFPY: 1/4T, 117°F (Axial Flaw) 3/4T, 105'F (Axial Flaw)

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1750 "

170Critical Limit IHeatup Curve

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- 200'F > T > 120°F 80 °F/hr

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0 50 100 150 200 250 300 350 400 450 500 550 RCS Temperature (Deg. F, 10 Deg. F per division)

• Curve is Applicable for RCS Vacuum fill FIGURE 3.4-2 REACTOR COOLANT SYSTEM HEATUP LIMITATIONS - APPLICABLE UP TO 55 EFPY

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Insert B MATERIAL PROPERTY BASIS LIMITING MATERIAL: Lower Shell Plate RI 808-1 without using surveillance data, Position 1.1 LIMITING ART VALUES AT 55 EFPY: 1/4T, 1177F (Axial Flaw) 3/4T, 1057F (Axial Flaw)

Curves applicable for the first 55 EFPY and contain margins for possible instrument errors 2500 2250 2000 Li..

1750 C

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> 1500 F--

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Lo) 1000 750 Composite Cooldown Curve Indicated RCS Maximum Allowable C,) 5) Temperature Cooldown Rate W~ 500 T < 150°F 20°F/hr T > 150°F 100°F/hr 250 0 I . . I . . . . ..I . . . .I . .

0 50 100 150 200 250 300 350 400 450 500 550 RCS Temperature (Deg. F, 10 Deg. F per division)

• Curve is Applicable for RCS Vacuum fill FIGURE 3.4-3 REACTOR COOLANT SYSTEM COOLDOWN LIMITATIONS - APPLICABLE UP TO 55 EFPY