ML22240A056

Changes Related to AP1000 Gts Subsection 3.4.2, RCS Minimum Temperature for Criticality

ML22240A056
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Issue date:	05/27/2015
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GTST AP1000-O23-3.4.2, Rev. 1 Date report generated:

Wednesday, May 27, 2015 Page 1 Advanced Passive 1000 (AP1000)

Generic Technical Specification Traveler (GTST)

Title:

Changes Related to LCO 3.4.2, RCS Minimum Temperature for Criticality I.

Technical Specifications Task Force (TSTF) Travelers, Approved Since Revision 2 of STS NUREG-1431, and Used to Develop this GTST TSTF Number and

Title:

TSTF-425-A, Rev 3, Relocate Surveillance Frequencies to Licensee Control - RITSTF Initiative 5b STS NUREGs Affected:

TSTF-425-A, Rev 3: NUREGs 1430, 1431, 1432, 1433, and 1434 NRC Approval Date:

TSTF-425-A, Rev. 3: 06-Jul-09 TSTF Classification:

TSTF-425-A, Rev 3: Technical Change

GTST AP1000-O23-3.4.2, Rev. 1 Date report generated:

Wednesday, May 27, 2015 Page 2 II.

Reference Combined License (RCOL) Standard Departures (Std. Dep.), RCOL COL Items, and RCOL Plant-Specific Technical Specifications (PTS) Changes Used to Develop this GTST RCOL Std. Dep. Number and

Title:

There are no Vogtle departures applicable to GTS 3.4.2.

RCOL COL Item Number and

Title:

There are no Vogtle COL items applicable to GTS 3.4.2.

RCOL PTS Change Number and

Title:

VEGP LAR DOC A003: References to various Chapters and Sections of the Final Safety Analysis Report (FSAR) are revised to include FSAR.

GTST AP1000-O23-3.4.2, Rev. 1 Date report generated:

Wednesday, May 27, 2015 Page 3 III.

Comments on Relations Among TSTFs, RCOL Std. Dep., RCOL COL Items, and RCOL PTS Changes This section discusses the considered changes that are: (1) applicable to operating reactor designs, but not to the AP1000 design; (2) already incorporated in the GTS; or (3) superseded by another change.

TSTF-425-A deferred for future consideration.

GTST AP1000-O23-3.4.2, Rev. 1 Date report generated:

Wednesday, May 27, 2015 Page 4 IV.

Additional Changes Proposed as Part of this GTST (modifications proposed by NRC staff and/or clear editorial changes or deviations identified by preparer of GTST)

APOG Recommended Changes to Improve the Bases Throughout the Bases, references to Sections and Chapters of the FSAR do not include the FSAR clarifier. Since these Section and Chapter references are to an external document, it is appropriate to include the FSAR modifier. (DOC A003)

Replace the symbol in the second paragraph, first sentence of the ASA section of the Bases with are greater than or equal to to provide improved clarity, consistency, and operator usability.

GTST AP1000-O23-3.4.2, Rev. 1 Date report generated:

Wednesday, May 27, 2015 Page 5 V.

Applicability Affected Generic Technical Specifications and Bases:

Subsection 3.4.2, RCS Minimum Temperature for Criticality Changes to the Generic Technical Specifications and Bases:

The symbol is replaced with are greater than or equal to in the second paragraph, first sentence of the ASA section of the Bases. (APOG Comment)

The acronym FSAR is added to modify Section and Chapter in references to the FSAR throughout the Bases. (DOC A003) (APOG Comment)

GTST AP1000-O23-3.4.2, Rev. 1 Date report generated:

Wednesday, May 27, 2015 Page 6 VI.

Traveler Information Description of TSTF changes:

Not Applicable Rationale for TSTF changes:

Not Applicable Description of changes in RCOL Std. Dep., RCOL COL Item(s), and RCOL PTS Changes:

Not Applicable Rationale for changes in RCOL Std. Dep., RCOL COL Item(s), and RCOL PTS Changes:

Not Applicable Description of additional changes proposed by NRC staff/preparer of GTST:

The acronym FSAR is added to modify Section and Chapter in references to the FSAR throughout the Bases. (DOC A003) (APOG Comment)

Replace the symbol with are greater than or equal to in the second paragraph, first sentence of the ASA section of the Bases. (APOG Comment)

Rationale for additional changes proposed by NRC staff/preparer of GTST:

Since Bases references to FSAR Sections and Chapters are to an external document, it is appropriate to include the FSAR modifier.

Replacing the symbol in the ASA section of the Bases with text is a non-technical change that provides improved clarity, consistency, and operator usability.

GTST AP1000-O23-3.4.2, Rev. 1 Date report generated:

Wednesday, May 27, 2015 Page 7 VII. GTST Safety Evaluation Technical Analysis:

The changes are editorial, clarifying, grammatical, or otherwise considered administrative.

These changes do not affect the technical content, but improve the readability, implementation, and understanding of the requirements, and are therefore acceptable.

Having found that this GTSTs proposed changes to the GTS and Bases are acceptable, the NRC staff concludes that AP1000 STS Subsection 3.4.2 is an acceptable model Specification for the AP1000 standard reactor design.

References to Previous NRC Safety Evaluation Reports (SERs):

None

GTST AP1000-O23-3.4.2, Rev. 1 Date report generated:

Wednesday, May 27, 2015 Page 8 VIII. Review Information Evaluator Comments:

None Randy Belles Oak Ridge National Laboratory 865-574-0388 Review Information:

Availability for public review and comment on Revision 0 of this traveler approved by NRC staff on 5/16/2014.

APOG Comments (Ref. 7) and Resolutions:

1.

(Internal # 3) Throughout the Bases, references to Sections and Chapters of the FSAR do not include the FSAR clarifier. Since these Section and Chapter references are to an external document, it is appropriate (DOC A003) to include the FSAR modifier. This is resolved by adding the FSAR modifier as appropriate.

2.

(Internal #13) Many GTSTs evaluated TSTF-425 with the following note: Risk-informed TS changes will be considered at a later time for application to the AP1000 STS.

The NRC approval of TSTF-425, and model safety evaluation provided in the CLIIP for TSTF-425, are generically applicable to any designs Technical Specifications. As such, the replacement of certain Frequencies with a Surveillance Frequency Control Program should be included in the GTST for AP1000 STS NUREG.

However, implementation in the AP1000 STS should not reflect optional (i.e., bracketed) material showing retention of fixed Surveillance Frequencies where relocation to a Surveillance Frequency Control Program is acceptable. Since each represented AP1000 Utility is committed to maintaining standardization, there is no rationale for an AP1000 STS that includes bracketed options.

Consistent with TSTF-425 criteria, replace applicable Surveillance Frequencies with In accordance with the Surveillance Frequency control Program and add that Program as new AP1000 STS Specification 5.5.15.

NRC Staff disagreed with implementing TSTF-425 in the initial version of the STS.

Although the APOG thinks the analysis supporting this traveler is general enough to be applicable to AP1000, staff thinks an AP1000-specific proposal from APOG is needed to identify any GTS SRs that should be excluded. Also, with the adoption of a Surveillance Frequency Control Program (SFCP) in the AP1000 STS, bracketed Frequencies, which provide a choice between the GTS Frequency and the SFCP Frequency, are needed because the NRC will use the AP1000 STS as a reference, and to be consistent with NUREG-1431, Rev. 4. APOG was requested to consider proposing an AP1000 version of TSTF-425 for a subsequent revision of the STS.

GTST AP1000-O23-3.4.2, Rev. 1 Date report generated:

Wednesday, May 27, 2015 Page 9

3.

(Internal # 228) In GTST Section XI and XII, the heading in upper right corner has a large space after Temperature, and before for Criticality. This is resolved by removing the extra spaces.

4.

(Internal # 229) APOG recommends replacing the symbol in the second paragraph, first sentence of the ASA section of the Bases with are greater than or equal to to provide improved clarity, consistency, and operator usability. This is resolved by making the recommended change.

NRC Final Approval Date: 5/27/2015 NRC

Contact:

Hien Le United States Nuclear Regulatory Commission 301-415-1511 Hien.Le@nrc.gov

GTST AP1000-O23-3.4.2, Rev. 1 Date report generated:

Wednesday, May 27, 2015 Page 10 IX.

Evaluator Comments for Consideration in Finalizing Technical Specifications and Bases None

GTST AP1000-O23-3.4.2, Rev. 1 Date report generated:

Wednesday, May 27, 2015 Page 11 X.

References Used in GTST

1.

AP1000 DCD, Revision 19, Section 16, Technical Specifications, June 2011 (ML11171A500).

2.

Southern Nuclear Operating Company, Vogtle Electric Generating Plant, Units 3 and 4, Technical Specifications Upgrade License Amendment Request, February 24, 2011 (ML12065A057).

3.

NRC Safety Evaluation (SE) for Amendment No. 13 to Combined License (COL) No.

NPF-91 for Vogtle Electric Generating Plant (VEGP) Unit 3, and Amendment No. 13 to COL No. NPF-92 for VEGP Unit 4, September 9, 2013, ADAMS Package Accession No. ML13238A337, which contains:

ML13238A355 Cover Letter - Issuance of License Amendment No. 13 for Vogtle Units 3 and 4 (LAR 12-002).

ML13238A359 - Amendment No. 13 to COL No. NPF-91 ML13239A256 - Amendment No. 13 to COL No. NPF-92 ML13239A284 Enclosure 3 - Revised plant-specific TS pages (Attachment to Amendment No. 13)

ML13239A287 - Safety Evaluation (SE), and Attachment 1 - Acronyms ML13239A288 SE Attachment 2 - Table A - Administrative Changes ML13239A319 SE Attachment 3 - Table M - More Restrictive Changes ML13239A333 SE Attachment 4 - Table R - Relocated Specifications ML13239A331 SE Attachment 5 - Table D - Detail Removed Changes ML13239A316 SE Attachment 6 - Table L - Less Restrictive Changes The following documents were subsequently issued to correct an administrative error in :

ML13277A616 Letter - Correction To The Attachment (Replacement Pages) - Vogtle Electric Generating Plant Units 3 and 4-Issuance of Amendment Re:

Technical Specifications Upgrade (LAR 12-002) (TAC No. RP9402)

ML13277A637 - Revised plant-specific TS pages (Attachment to Amendment No. 13) (corrected)

4.

TSTF-GG-05-01, Writer's Guide for Plant-Specific Improved Technical Specifications, June 2005.

5.

RAI Letter No. 01 Related to License Amendment Request (LAR)12-002 for the Vogtle Electric Generating Plant Units 3 and 4 Combined Licenses, September 7, 2012 (ML12251A355).

6.

Southern Nuclear Operating Company, Vogtle Electric Generating Plant, Units 3 and 4, Response to Request for Additional Information Letter No. 01 Related to License Amendment Request LAR-12-002, ND-12-2015, October 04, 2012 (ML12286A363 and ML12286A360)

GTST AP1000-O23-3.4.2, Rev. 1 Date report generated:

Wednesday, May 27, 2015 Page 12

7.

APOG-2014-008, APOG (AP1000 Utilities) Comments on AP1000 Standardized Technical Specifications (STS) Generic Technical Specification Travelers (GTSTs), Docket ID NRC-2014-0147, September 22, 2014 (ML14265A493).

GTST AP1000-O23-3.4.2, Rev. 1 Date report generated:

Wednesday, May 27, 2015 Page 13 XI.

MARKUP of the Applicable GTS Subsection for Preparation of the STS NUREG The entire section of the Specifications and the Bases associated with this GTST is presented next.

Changes to the Specifications and Bases are denoted as follows: Deleted portions are marked in strikethrough red font, and inserted portions in bold blue font.

GTST AP1000-O23-3.4.2, Rev. 1 RCS Minimum Temperature for Criticality 3.4.2 AP1000 STS 3.4.2-1 Amendment 0Rev. 0 Revision 19 Date report generated:

Wednesday, May 27, 2015 Page 14 3.4 REACTOR COOLANT SYSTEM (RCS) 3.4.2 RCS Minimum Temperature for Criticality LCO 3.4.2 Each RCS loop average temperature (Tavg) shall be 551°F.

APPLICABILITY:

MODE 1, MODE 2 with keff 1.0.

ACTIONS CONDITION REQUIRED ACTION COMPLETION TIME A. Tavg in one or more RCS loops not within limit.

A.1 Be in MODE 2 with keff < 1.0.

30 minutes SURVEILLANCE REQUIREMENTS SURVEILLANCE FREQUENCY SR 3.4.2.1 Verify RCS Tavg in each loop 551°F.

12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />

GTST AP1000-O23-3.4.2, Rev. 1 RCS Minimum Temperature for Criticality B 3.4.2 AP1000 STS B 3.4.2-1 Amendment 0Rev. 0 Revision 19 Date report generated:

Wednesday, May 27, 2015 Page 15 B 3.4 REACTOR COOLANT SYSTEM (RCS)

B 3.4.2 RCS Minimum Temperature for Criticality BASES BACKGROUND This LCO is based upon meeting several major considerations before the reactor can be made critical and while the reactor is critical.

The first consideration is moderator temperature coefficient (MTC),

LCO 3.1.3, Moderator Temperature Coefficient (MTC). In the transient and accident analyses, the MTC is assumed to be in a range from zero to negative and the operating temperature is assumed to be within the nominal operating envelope while the reactor is critical. The LCO on minimum temperature for criticality helps ensure the plant is operated consistent with these assumptions.

The second consideration is the protective instrumentation. Because certain protective instrumentation (e.g., excore neutron detectors) can be affected by moderator temperature, a temperature value within the nominal operating envelope is chosen to ensure proper indication and response while the reactor is critical.

The third consideration is the pressurizer operating characteristics. The transient and accident analyses assume that the pressurizer is within its normal startup and operating range (i.e., saturated conditions and steam bubble present). It is also assumed that the RCS temperature is within its normal expected range for startup and power operation. Since the density of the water, and hence the response of the pressurizer to transients, depends upon the initial temperature of the moderator, a minimum value for moderator temperature within the nominal operating envelope is chosen.

The fourth consideration is that the reactor vessel is above its minimum nil-ductility reference temperature when the reactor is critical.

APPLICABLE SAFETY ANALYSES Although the RCS minimum temperature for criticality is not itself an initial condition assumed in Design Basis Accidents (DBAs), the closely aligned temperature for hot zero power (HZP) is a process variable that is an initial condition of DBAs, such as the rod cluster control assembly (RCCA) withdrawal, RCCA ejection, and main steam line break accidents performed at zero power that either assume the failure of, or presents a challenge to, the integrity of a fission product barrier.

GTST AP1000-O23-3.4.2, Rev. 1 RCS Minimum Temperature for Criticality B 3.4.2 AP1000 STS B 3.4.2-2 Amendment 0Rev. 0 Revision 19 Date report generated:

Wednesday, May 27, 2015 Page 16 BASES APPLICABLE SAFETY ANALYSES (continued)

All low power safety analyses assume initial RCS loop temperatures are greater than or equal to the HZP temperature of 557°F (Ref. 1). The minimum temperature for criticality limitation provides a small band, 6°F, for critical operation below HZP. This band allows critical operation below HZP during plant startup and does not adversely affect any safety analyses since the MTC is not significantly affected by the small temperature difference between HZP and the minimum temperature for criticality.

The RCS minimum temperature for criticality parameter satisfies Criterion 2 of 10 CFR 50.36(c)(2)(ii).

LCO Compliance with the LCO ensures that the reactor will not be made or maintained critical (keff 1.0) at a temperature less than a small band below the HZP temperature, which is assumed in the safety analysis.

Failure to meet the requirements of this LCO may produce initial conditions inconsistent with the initial conditions assumed in the safety analysis.

APPLICABILITY In MODE 1 and MODE 2 with keff 1.0, LCO 3.4.2 is applicable since the reactor can only be critical (keff 1.0) in these MODES.

The special test exception of LCO 3.1.8, MODE 2 PHYSICS TEST Exceptions, permits PHYSICS TESTS to be performed at 5.0% RTP with RCS loop average temperatures slightly lower than normally allowed so that fundamental nuclear characteristics of the core can be verified. In order for nuclear characteristics to be accurately measured, it may be necessary to operate outside the normal restrictions of this LCO. For example, to measure the MTC at beginning of cycle, it is necessary to allow RCS loop average temperatures to fall below Tno load, which may cause RCS loop average temperatures to fall below the temperature limit of this LCO.

GTST AP1000-O23-3.4.2, Rev. 1 RCS Minimum Temperature for Criticality B 3.4.2 AP1000 STS B 3.4.2-3 Amendment 0Rev. 0 Revision 19 Date report generated:

Wednesday, May 27, 2015 Page 17 BASES ACTIONS A.1 If the parameters that are outside the limit cannot be restored, the plant must be brought to a MODE in which the LCO does not apply. To achieve this status, the plant must be brought to MODE 2 with keff < 1.0 within 30 minutes. Rapid reactor shutdown can be readily and practically achieved within a 30 minute period. The allowed time is reasonable, based on operating experience, to reach MODE 2 with keff < 1.0 in an orderly manner and without challenging plant systems.

SURVEILLANCE REQUIREMENTS SR 3.4.2.1 RCS loop average temperature is required to be verified at or above 551°F every 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. The SR to verify RCS loop average temperatures every 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> takes into account indications and alarms that are continuously available to the operator in the control room and is consistent with other routine Surveillances which are typically performed once per shift. In addition, operators are trained to be sensitive to RCS temperature during approach to criticality and will ensure that the minimum temperature for criticality is met as criticality is approached.

REFERENCES

1.

FSAR Chapter 15, Accident Analyses.

GTST AP1000-O23-3.4.2, Rev. 1 Date report generated:

Wednesday, May 27, 2015 Page 18 XII. Applicable STS Subsection After Incorporation of this GTSTs Modifications The entire subsection of the Specifications and the Bases associated with this GTST, following incorporation of the modifications, is presented next.

GTST AP1000-O23-3.4.2, Rev. 1 RCS Minimum Temperature for Criticality 3.4.2 AP1000 STS 3.4.2-1 Rev. 0 Date report generated:

Wednesday, May 27, 2015 Page 19 3.4 REACTOR COOLANT SYSTEM (RCS) 3.4.2 RCS Minimum Temperature for Criticality LCO 3.4.2 Each RCS loop average temperature (Tavg) shall be 551°F.

APPLICABILITY:

MODE 1, MODE 2 with keff 1.0.

ACTIONS CONDITION REQUIRED ACTION COMPLETION TIME A. Tavg in one or more RCS loops not within limit.

A.1 Be in MODE 2 with keff < 1.0.

30 minutes SURVEILLANCE REQUIREMENTS SURVEILLANCE FREQUENCY SR 3.4.2.1 Verify RCS Tavg in each loop 551°F.

12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />

GTST AP1000-O23-3.4.2, Rev. 1 RCS Minimum Temperature for Criticality B 3.4.2 AP1000 STS B 3.4.2-1 Rev. 0 Date report generated:

Wednesday, May 27, 2015 Page 20 B 3.4 REACTOR COOLANT SYSTEM (RCS)

B 3.4.2 RCS Minimum Temperature for Criticality BASES BACKGROUND This LCO is based upon meeting several major considerations before the reactor can be made critical and while the reactor is critical.

The first consideration is moderator temperature coefficient (MTC),

LCO 3.1.3, Moderator Temperature Coefficient (MTC). In the transient and accident analyses, the MTC is assumed to be in a range from zero to negative and the operating temperature is assumed to be within the nominal operating envelope while the reactor is critical. The LCO on minimum temperature for criticality helps ensure the plant is operated consistent with these assumptions.

The second consideration is the protective instrumentation. Because certain protective instrumentation (e.g., excore neutron detectors) can be affected by moderator temperature, a temperature value within the nominal operating envelope is chosen to ensure proper indication and response while the reactor is critical.

The third consideration is the pressurizer operating characteristics. The transient and accident analyses assume that the pressurizer is within its normal startup and operating range (i.e., saturated conditions and steam bubble present). It is also assumed that the RCS temperature is within its normal expected range for startup and power operation. Since the density of the water, and hence the response of the pressurizer to transients, depends upon the initial temperature of the moderator, a minimum value for moderator temperature within the nominal operating envelope is chosen.

The fourth consideration is that the reactor vessel is above its minimum nil-ductility reference temperature when the reactor is critical.

APPLICABLE SAFETY ANALYSES Although the RCS minimum temperature for criticality is not itself an initial condition assumed in Design Basis Accidents (DBAs), the closely aligned temperature for hot zero power (HZP) is a process variable that is an initial condition of DBAs, such as the rod cluster control assembly (RCCA) withdrawal, RCCA ejection, and main steam line break accidents performed at zero power that either assume the failure of, or presents a challenge to, the integrity of a fission product barrier.

GTST AP1000-O23-3.4.2, Rev. 1 RCS Minimum Temperature for Criticality B 3.4.2 AP1000 STS B 3.4.2-2 Rev. 0 Date report generated:

Wednesday, May 27, 2015 Page 21 BASES APPLICABLE SAFETY ANALYSES (continued)

All low power safety analyses assume initial RCS loop temperatures are greater than or equal to the HZP temperature of 557°F (Ref. 1). The minimum temperature for criticality limitation provides a small band, 6°F, for critical operation below HZP. This band allows critical operation below HZP during plant startup and does not adversely affect any safety analyses since the MTC is not significantly affected by the small temperature difference between HZP and the minimum temperature for criticality.

The RCS minimum temperature for criticality parameter satisfies Criterion 2 of 10 CFR 50.36(c)(2)(ii).

LCO Compliance with the LCO ensures that the reactor will not be made or maintained critical (keff 1.0) at a temperature less than a small band below the HZP temperature, which is assumed in the safety analysis.

Failure to meet the requirements of this LCO may produce initial conditions inconsistent with the initial conditions assumed in the safety analysis.

APPLICABILITY In MODE 1 and MODE 2 with keff 1.0, LCO 3.4.2 is applicable since the reactor can only be critical (keff 1.0) in these MODES.

The special test exception of LCO 3.1.8, MODE 2 PHYSICS TEST Exceptions, permits PHYSICS TESTS to be performed at 5.0% RTP with RCS loop average temperatures slightly lower than normally allowed so that fundamental nuclear characteristics of the core can be verified. In order for nuclear characteristics to be accurately measured, it may be necessary to operate outside the normal restrictions of this LCO. For example, to measure the MTC at beginning of cycle, it is necessary to allow RCS loop average temperatures to fall below Tno load, which may cause RCS loop average temperatures to fall below the temperature limit of this LCO.

GTST AP1000-O23-3.4.2, Rev. 1 RCS Minimum Temperature for Criticality B 3.4.2 AP1000 STS B 3.4.2-3 Rev. 0 Date report generated:

Wednesday, May 27, 2015 Page 22 BASES ACTIONS A.1 If the parameters that are outside the limit cannot be restored, the plant must be brought to a MODE in which the LCO does not apply. To achieve this status, the plant must be brought to MODE 2 with keff < 1.0 within 30 minutes. Rapid reactor shutdown can be readily and practically achieved within a 30 minute period. The allowed time is reasonable, based on operating experience, to reach MODE 2 with keff < 1.0 in an orderly manner and without challenging plant systems.

SURVEILLANCE REQUIREMENTS SR 3.4.2.1 RCS loop average temperature is required to be verified at or above 551°F every 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. The SR to verify RCS loop average temperatures every 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> takes into account indications and alarms that are continuously available to the operator in the control room and is consistent with other routine Surveillances which are typically performed once per shift. In addition, operators are trained to be sensitive to RCS temperature during approach to criticality and will ensure that the minimum temperature for criticality is met as criticality is approached.

REFERENCES

1.

FSAR Chapter 15, Accident Analyses.