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Enclosure 2 - Volume 6 - Improved Technical Specifications Conversion, ITS Section 3.1 Reactivity Control Systems, Revision 0
	ML13329A858
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Site:	Sequoyah
Issue date:	11/22/2013
From:	; Tennessee Valley Authority
To:	; Office of Nuclear Reactor Regulation
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Enclosure 2, Volume 6, Rev. 0, Page 1 of 356 ENCLOSURE 2 VOLUME 6 SEQUOYAH NUCLEAR PLANT UNIT 1 AND UNIT 2 IMPROVED TECHNICAL SPECIFICATIONS CONVERSION ITS SECTION 3.1 REACTIVITY CONTROL SYSTEMS Revision 0 Enclosure 2, Volume 6, Rev. 0, Page 1 of 356

Enclosure 2, Volume 6, Rev. 0, Page 2 of 356 LIST OF ATTACHMENTS

1. ITS Section 3.1.1 - Shutdown Margin

2. ITS Section 3.1.2 - Core Reactivity

3. ITS Section 3.1.3 - Moderator Temperature Coefficient (MTC)

4. ITS Section 3.1.4 - Rod Group Alignment Limits

5. ITS Section 3.1.5 - Shutdown Bank Insertion Limits

6. ITS Section 3.1.6 - Control Bank Insertion Limits

7. ITS Section 3.1.7 - Rod Position Indication

8. ITS Section 3.1.8 - Physics Test Exceptions - MODE 2

9. Relocated/Deleted Current Technical Specifications (CTS)

Enclosure 2, Volume 6, Rev. 0, Page 2 of 356

, Volume 6, Rev. 0, Page 3 of 356 ATTACHMENT 1 ITS 3.1.1, SHUTDOWN MARGIN (SDM) , Volume 6, Rev. 0, Page 3 of 356

Enclosure 2, Volume 6, Rev. 0, Page 4 of 356 Current Technical Specification (CTS) Markup and Discussion of Changes (DOCs)

Enclosure 2, Volume 6, Rev. 0, Page 4 of 356

Enclosure 2, Volume 6, Rev. 0, Page 5 of 356 ITS A01 ITS 3.1.1 3/4.1 REACTIVITY CONTROL SYSTEMS A01 3/4.1.1 BORATION CONTROL A02 SHUTDOWN MARGIN - Tavg Greater Than 200°F LIMITING CONDITION FOR OPERATION within the limits specified in the COLR LA01 LCO 3.1.1 3.1.1.1 The SHUTDOWN MARGIN shall be greater than or equal to 1.6% delta k/k for 4 loop operation. A04 keff < 1.0 A03 Applicability APPLICABILITY: MODES 1, 2*, 3, and 4. See ITS 3.1.6 not within limits LA01 ACTION:

within 15 minutes L01 ACTION A With the SHUTDOWN MARGIN less than 1.6% delta k/k, immediately initiate and continue boration at L02 greater than or equal to 35 gpm of a solution containing greater than or equal to 6120 ppm boron or equivalent until the required SHUTDOWN MARGIN is restored.

SURVEILLANCE REQUIREMENTS within the limits specified in the COLR LA01 SR 3.1.1.1 4.1.1.1.1 The SHUTDOWN MARGIN shall be determined to be greater than or equal to 1.6% delta k/k:

See ITS

a. Within one hour after detection of an inoperable control rod(s) and at least once per 12 3.1.4 hours4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months thereafter while the rod(s) is inoperable. If the inoperable control rod is immovable or untrippable, the above required SHUTDOWN MARGIN shall be verified acceptable See ITS Chapter 1.0 with an increased allowance for the withdrawn worth of the immovable or untrippable control rod(s).

b. When in MODE 1 or MODE 2 with Keff greater than or equal to 1.0, at least once per 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months by verifying that control bank withdrawal is within the limits of Specification 3.1.3.6.

See ITS

c. When in MODE 2 with Keff less than 1.0, within 4 hours4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months prior to achieving reactor 3.1.6 criticality by verifying that the predicted critical control rod position is within the limits of Specification 3.1.3.6.

____________________ A04

See Special Test Exception 3.10.1 November 26, 1993 SEQUOYAH - UNIT 1 3/4 1-1 Amendment No. 172 Page 1 of 6 Enclosure 2, Volume 6, Rev. 0, Page 5 of 356

Enclosure 2, Volume 6, Rev. 0, Page 6 of 356 ITS A01 ITS 3.1.1 REACTIVITY CONTROL SYSTEMS SURVEILLANCE REQUIREMENTS (Continued)

d. Prior to initial operation above 5% RATED THERMAL POWER after each fuel loading, by consideration of the factors of e below, with the control banks at the maximum insertion L03 limit of Specification 3.1.3.6.

MODE 2 with keff < 1.0 M01 SR 3.1.1.1 e. When in MODES 3 or 4, at least once per 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months by consideration of the following factors: In accordance with the Surveillance Frequency Control Program LA02

1. Reactor coolant system boron concentration,

2. Control rod position, LA03

3. Reactor coolant system average temperature,

4. Fuel burnup based on gross thermal energy generation,

5. Xenon concentration, and

6. Samarium concentration.

4.1.1.1.2 The overall core reactivity balance shall be compared to predicted values to demonstrate agreement within + 1% delta k/k at least once per 31 Effective Full Power Days (EFPD). This comparison See ITS shall consider at least those factors stated in Specification 4.1.1.1.1.e, above. The predicted reactivity 3.1.2 values shall be adjusted (normalized) to correspond to the actual core conditions prior to exceeding a fuel burnup of 60 Effective Full Power Days after each fuel loading.

SEQUOYAH - UNIT 1 3/4 1-2 Page 2 of 6 Enclosure 2, Volume 6, Rev. 0, Page 6 of 356

Enclosure 2, Volume 6, Rev. 0, Page 7 of 356 ITS A01 ITS 3.1.1 REACTIVITY CONTROL SYSTEMS A02 SHUTDOWN MARGIN - Tavg Less Than or Equal to 200°F LIMITING CONDITION FOR OPERATION within the limits specified in the COLR LA01 LCO 3.1.1 3.1.1.2 The SHUTDOWN MARGIN shall be greater than or equal to 1.0% delta k/k.

Applicability APPLICABILITY: MODE 5.

not within limits LA01 ACTION:

within 15 minutes L01 ACTION A With the SHUTDOWN MARGIN less than 1.0% delta k/k, immediately initiate and continue boration at L02 greater than or equal to 35 gpm of a solution containing greater than or equal to 6120 ppm boron or equivalent until the required SHUTDOWN MARGIN is restored.

SURVEILLANCE REQUIREMENTS within the limits specified in the COLR LA01 SR 3.1.1.1 4.1.1.2 The SHUTDOWN MARGIN shall be determined to be greater than or equal to 1.0% delta k/k:

See ITS

a. Within one hour after detection of an inoperable control rod(s) and at least once per 12 3.1.4 hours4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months thereafter while the rod(s) is inoperable. If the inoperable control rod is immovable or untrippable, the SHUTDOWN MARGIN shall be verified acceptable with an increased See ITS Chapter 1.0 allowance for the withdrawn worth of the immovable or untrippable control rod(s).

b. At least once per 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months by consideration of the following factors:

In accordance with the Surveillance Frequency Control Program LA02

1. Reactor coolant system boron concentration,

2. Control rod position,

3. Reactor coolant system average temperature, LA03

4. Fuel burnup based on gross thermal energy generation,

5. Xenon concentration, and

6. Samarium concentration.

November 26, 1993 SEQUOYAH - UNIT 1 3/4 1-3 Amendment No. 12, 172 Page 3 of 6 Enclosure 2, Volume 6, Rev. 0, Page 7 of 356

Enclosure 2, Volume 6, Rev. 0, Page 8 of 356 ITS A01 ITS 3.1.1 3/4.1 REACTIVITY CONTROL SYSTEMS A01 3/4.1.1 BORATION CONTROL A02 SHUTDOWN MARGIN - Tavg 200°F LIMITING CONDITION FOR OPERATION within the limits specified in the COLR LA01 LCO 3.1.1 3.1.1.1 The SHUTDOWN MARGIN shall be greater than or equal to 1.6% delta k/k for 4 loop operation. A04 keff < 1.0 A03 Applicability APPLICABILITY: MODES 1, 2*, 3, and 4. See ITS

3.1.6 ACTION

not within limits LA01 within 15 minutes L01 ACTION A With the SHUTDOWN MARGIN less than 1.6% delta k/k, immediately initiate and continue boration at L02 greater than or equal to 35 gpm of a solution containing greater than or equal to 6120 ppm boron or equivalent until the required SHUTDOWN MARGIN is restored.

SURVEILLANCE REQUIREMENTS within the limits specified in the COLR LA01 SR 3.1.1.1 4.1.1.1.1 The SHUTDOWN MARGIN shall be determined to be greater than or equal to 1.6% delta k/k:

See ITS

a. Within one hour after detection of an inoperable control rod(s) and at least once per 3.1.4 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months thereafter while the rod(s) is inoperable. If the inoperable control rod is immovable or untrippable, the above required SHUTDOWN MARGIN shall be verified See ITS Chapter 1.0 acceptable with an increased allowance for the withdrawn worth of the immovable or untrippable control rod(s).

b. When in MODE 1 or MODE 2 with Keff greater than or equal to 1.0, at least once per 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months by verifying that control bank withdrawal is within the limits of Specification 3.1.3.6.

See ITS 3.1.6

c. When in MODE 2, with Keff less than 1.0, within 4 hours4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months prior to achieving reactor criticality by verifying that the predicted critical control rod position is within the limits of Specification 3.1.3.6.

d. Prior to initial operation above 5% RATED THERMAL POWER after each fuel loading, by consideration of the factors of e below, with the control banks at the maximum insertion L03 limit of Specification 3.1.3.6.

A04

See Special Test Exception 3.10.1 November 26, 1993 SEQUOYAH - UNIT 2 3/4 1-1 Amendment No. 163 Page 4 of 6 Enclosure 2, Volume 6, Rev. 0, Page 8 of 356

Enclosure 2, Volume 6, Rev. 0, Page 9 of 356 ITS A01 ITS 3.1.1 REACTIVITY CONTROL SYSTEMS SURVEILLANCE REQUIREMENTS (Continued)

MODE 2 with keff < 1.0 M01 SR 3.1.1.1 e. When in MODES 3 or 4, at least once per 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months by consideration of the following factors: In accordance with the Surveillance Frequency Control Program LA02

1. Reactor coolant system boron concentration,

2. Control rod position, LA03

3. Reactor coolant system average temperature,

4. Fuel burnup based on gross thermal energy generation,

5. Xenon concentration, and

6. Samarium concentration.

4.1.1.1.2 The overall core reactivity balance shall be compared to predicted values to demonstrate agreement within +/- 1% delta k/k at least once per 31 Effective Full Power Days (EFPD). This comparison See ITS shall consider at least those factors stated in Specification 4.1.1.1.1.e, above. The predicted reactivity 3.1.2 values shall be adjusted (normalized) to correspond to the actual core conditions prior to exceeding a fuel burnup of 60 Effective Full Power Days after each fuel loading.

SEQUOYAH - UNIT 2 3/4 1-2 Page 5 of 6 Enclosure 2, Volume 6, Rev. 0, Page 9 of 356

Enclosure 2, Volume 6, Rev. 0, Page 10 of 356 ITS A01 ITS 3.1.1 REACTIVITY CONTROL SYSTEMS A02 SHUTDOWN MARGIN - Tavg Less Than or Equal to 200°F LIMITING CONDITION FOR OPERATION within the limits specified in the COLR LA01 LCO 3.1.1 3.1.1.2 The SHUTDOWN MARGIN shall be greater than or equal to 1.0% delta k/k.

Applicability APPLICABILITY: MODE 5.

not within limits LA01 ACTION:

within 15 minutes L01 ACTION A With the SHUTDOWN MARGIN less than 1.0% delta k/k, immediately initiate and continue boration at L02 greater than or equal to 35 gpm of a solution containing greater than or equal to 6120 ppm boron or equivalent until the required SHUTDOWN MARGIN is restored.

SURVEILLANCE REQUIREMENTS within the limits specified in the COLR LA01 SR 3.1.1.1 4.1.1.2 The SHUTDOWN MARGIN shall be determined to be greater than or equal to 1.0% delta k/k:

See ITS

a. Within one hour after detection of an inoperable control rod(s) and at least once per 3.1.4 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months thereafter while the rod(s) is inoperable. If the inoperable control rod is immovable or untrippable, the SHUTDOWN MARGIN shall be verified acceptable with an See ITS Chapter 1.0 increased allowance for the withdrawn worth of the immovable or untrippable control rod(s).

b. At least once per 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months by consideration of the following factors:

In accordance with the Surveillance Frequency Control Program LA02

1. Reactor coolant system boron concentration,

2. Control rod position, LA03

3. Reactor coolant system average temperature,

4. Fuel burnup based on gross thermal energy generation,

5. Xenon concentration, and

6. Samarium concentration.

November 26, 1993 SEQUOYAH - UNIT 2 3/4 1-3 Amendment No. 163 Page 6 of 6 Enclosure 2, Volume 6, Rev. 0, Page 10 of 356

Enclosure 2, Volume 6, Rev. 0, Page 11 of 356 DISCUSSION OF CHANGES ITS 3.1.1, SHUTDOWN MARGIN (SDM)

ADMINISTRATIVE CHANGES A01 In the conversion of the Sequoyah Nuclear Plant (SQN) Current Technical Specifications (CTS) to the plant specific Improved Technical Specifications (ITS), certain changes (wording preferences, editorial changes, reformatting, revised numbering, etc.) are made to obtain consistency with NUREG - 1431, Rev. 4.0, "Standard Technical Specifications - Westinghouse Plants" (ISTS) and additional Technical Specification Task Force (TSTF) travelers included in this submittal.

These changes are designated as administrative changes and are acceptable because they do not result in technical changes to the CTS.

A02 CTS 3.1.1.1 provides the SHUTDOWN MARGIN (SDM) requirement in MODES 1, 2, 3, and 4 (i.e., Tavg greater than 200°F). CTS 3.1.1.2 provides the SDM requirement in MODE 5 (i.e., Tavg less than or equal to 200°F). ITS 3.1.1 provides the SDM requirement in MODE 2 with keff < 1.0 and MODES 3, 4, and 5.

This changes the CTS by combining the SDM requirements in MODE 2 with keff < 1.0 and MODES 3, 4, and 5. The change in Applicability for MODE 2 with keff < 1.0 is described in DOC A03.

This change is acceptable because the requirements have not changed.

Combining the Specifications is an editorial change. Any technical changes resulting from this combination are discussed in other DOCs. This change is designated as administrative because it does not result in a technical change to the CTS.

A03 CTS 3.1.1.1 provides the SDM requirement in MODES 1, 2, 3, and 4 (i.e., Tavg greater than 200°F). CTS 4.1.1.1.1 states, when in MODES 1 and 2 with keff 1.0, verify the control bank withdrawal is within the limits of Specification 3.1.3.6. ITS 3.1.1 is Applicable in MODE 2 with keff < 1.0 and MODES 3, 4, and 5. This changes the CTS by combining the SDM requirement in MODE 2 with keff < 1.0 and MODES 3, 4, and 5. The change in Applicability for MODE 1 and MODE 2 with keff 1.0 is described in ITS 3.1.6 (Control Bank Insertion Limits).

The purpose of CTS 3.1.1.1 is to ensure that the SDM assumed in the accident analysis is available. When the reactor is critical, SDM is verified by ensuring the control rods are within the control rod insertion limits. ITS 3.1.1 Applicability Bases state in MODES 1 and 2, SDM is ensured by complying with LCO 3.1.5, "Shutdown Bank Insertion Limits," and LCO 3.1.6, "Control Bank Insertion Limits." This change is acceptable because the SDM requirements have not changed. Even though CTS 3.1.1.1 is applicable in MODES 1 and 2, the CTS Surveillances only require the verification that control rod bank withdrawal is within the control rod insertion limits. The ITS verifies SDM in MODES 1 and 2 by the rod insertion limits. Any changes to the rod insertion limit requirements are discussed in DOCs for those Specifications. This change is designated as administrative because it does not result in a technical change to the CTS.

A04 CTS 3.1.1.1 Applicability is MODES 1, 2, 3, and 4 with a footnote (footnote *) for MODE 2 stating "See Special Test Exception 3.10.1." ITS 3.1.1 does not contain Sequoyah Unit 1 and Unit 2 Page 1 of 5 Enclosure 2, Volume 6, Rev. 0, Page 11 of 356

Enclosure 2, Volume 6, Rev. 0, Page 12 of 356 DISCUSSION OF CHANGES ITS 3.1.1, SHUTDOWN MARGIN (SDM) the footnote or a reference to the Special Test Exception. This changes the CTS by not including footnote

in the ITS.

The purpose of the footnote reference is to alert the user that a Special Test Exception exists that may modify the Applicability of the Specification. It is an ITS convention to not include these types of footnotes or cross-references. This change is designated as administrative as it incorporates an ITS convention with no technical change to the CTS.

MORE RESTRICTIVE CHANGES M01 CTS 4.1.1.1.1.e requires SDM to be determined to be within its limits every 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months when in MODES 3 and 4. ITS SR 3.1.1.1 requires SDM to be determined to be within its limits in MODE 2 with keff < 1.0 and MODES 3 and 4.

This changes the CTS by expanding the applicability of the Surveillance to include MODE 2 with keff < 1.0.

The purpose of CTS 4.1.1.1.1.e is to verify that sufficient SDM is available.

CTS 4.1.1.1.1.b states that when the reactor is in MODE 1 and MODE 2 with keff 1.0, SDM is verified by determining that the control rods are above the rod insertion limits. In MODE 2 with keff < 1.0, CTS 4.1.1.1.1.c verifies SDM by determining that the control rods are above the rod insertion limits. However, no CTS Surveillance requires a periodic verification of SDM when in MODE 2 with keff < 1.0. This change is acceptable because the ITS requires a specific verification that the SDM is within the limit when in MODE 2 with keff < 1.0 on a periodic basis. This change is designated as more restrictive because it expands the conditions under which a Surveillance must be performed.

RELOCATED SPECIFICATIONS None REMOVED DETAIL CHANGES LA01 (Type 6 - Removal of Cycle-Specific Parameter Limits from the Technical Specifications to the Core Operating Limits Report) CTS 3.1.1.1, CTS 3.1.1.1 ACTION and CTS 4.1.1.1.1 require the SDM to be greater than or equal to 1.6%

delta k/k when in MODES 1, 2, 3, and 4. CTS 3.1.1.2, CTS 3.1.1.2 ACTION and CTS 4.1.1.2.1 require the SDM to be greater than or equal to 1.0% delta k/k when in MODE 5. ITS LCO 3.1.1 requires the SDM to be within the limits specified in the COLR. ITS 3.1.1 ACTION A provides actions when the SDM is not within limits. ITS SR 3.1.1.1 requires verification that the SDM is within limits.

This changes the CTS by moving the SDM limits to the COLR.

The removal of these cycle-specific parameter limits from the Technical Specifications to the COLR is acceptable because the cycle-specific limits are developed or utilized under NRC-approved methodologies that will ensure that the safety limits are met. The NRC documented in Generic Letter 88-16, Sequoyah Unit 1 and Unit 2 Page 2 of 5 Enclosure 2, Volume 6, Rev. 0, Page 12 of 356

Enclosure 2, Volume 6, Rev. 0, Page 13 of 356 DISCUSSION OF CHANGES ITS 3.1.1, SHUTDOWN MARGIN (SDM)

"Removal of Cycle-Specific Parameter Limits From Technical Specifications,"

that this type of information is not necessary to be included in the Technical Specification to provide adequate protection of public health and safety. The ITS retains the SDM requirement. The methodologies used to develop the parameters in the COLR have obtained approval by the NRC in accordance with Generic Letter 88-16. Furthermore, this change is acceptable because the removed information will be adequately controlled in the COLR under the requirements provided in ITS 5.6.3, "Core Operating Limits Report." ITS 5.6.3 ensures the applicable limits (e.g., fuel thermal mechanical limits, core thermal hydraulic limits, Emergency Core Cooling System limits, and nuclear limits such as SDM, transient analysis limits, and accident analysis limits) of the safety analyses are met. This change is designated as a less restrictive removal of detail change because information relating to cycle-specific parameter limits is being removed from the Technical Specifications.

LA02 (Type 5 - Removal of SR Frequency to the Surveillance Frequency Control Program) CTS 4.1.1.1.1.e and CTS 4.1.1.2.b require SDM to be determined to be within its limits every 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months . ITS SR 3.1.1.1 requires a similar Surveillance and specifies the periodic Frequency as, "In accordance with the Surveillance Frequency Control Program." This changes the CTS by moving the specified Frequencies for this SR and associated Bases to the Surveillance Frequency Control Program.

The removal of these details related to Surveillance Requirement Frequencies from the Technical Specifications is acceptable, because this type of information is not necessary to be included in the Technical Specifications to provide adequate protection of public health and safety. The existing Surveillance Frequencies are removed from Technical Specifications and placed under licensee control pursuant to the methodology described in NEI 04-10. A new program (Surveillance Frequency Control Program) is being added to the Administrative Controls section of the Technical Specifications describing the control of Surveillance Frequencies. The surveillance test requirements remain in the Technical Specifications. The control of changes to the Surveillance Frequencies will be in accordance with the Surveillance Frequency Control Program. The Program shall ensure that Surveillance Requirements specified in the Technical Specifications are performed at intervals sufficient to assure the associated Limiting Conditions for Operation are met. This change is designated as a less restrictive removal of detail change, because the Surveillance Frequencies are being removed from the Technical Specifications.

LA03 (Type 3 - Removing Procedural Details for Meeting TS Requirements or Reporting Requirements) CTS 4.1.1.1.1.e and CTS 4.1.1.2.b require determination that the SDM is within limits, and specifically requires the consideration of the following factors: reactor coolant system boron concentration, control rod position, reactor coolant system average temperature, fuel burnup based on gross thermal energy generation, xenon concentration and samarium concentration. ITS SR 3.1.1.1 requires a determination that the SDM is within limits, but does not describe the factors that must be considered in the calculation. This information is moved to the Bases. This changes the CTS by removing details on how the SDM calculation is performed from the Specification and placing the information in the Bases.

Sequoyah Unit 1 and Unit 2 Page 3 of 5 Enclosure 2, Volume 6, Rev. 0, Page 13 of 356

Enclosure 2, Volume 6, Rev. 0, Page 14 of 356 DISCUSSION OF CHANGES ITS 3.1.1, SHUTDOWN MARGIN (SDM)

The removal of these details for performing Surveillance Requirements from the Technical Specifications is acceptable because this type of information is not necessary to be included in the Technical Specifications to provide adequate protection of public health and safety. The ITS retains the requirement that the SDM be within limits. The detail of how SDM is calculated does not need to appear in the specification in order for the requirement to apply. Also, this change is acceptable because the removed information will be adequately controlled in the ITS Bases. Changes to the Bases are controlled by the Technical Specification Bases Control Program in Chapter 5. This program provides for the evaluation of changes to ensure the Bases are properly controlled. This change is designated as a less restrictive removal of detail change because information relating to system design is being removed from the Technical Specifications.

LESS RESTRICTIVE CHANGES L01 (Category 3 - Relaxation of Completion Time) CTS 3.1.1.1 ACTION states when the SDM is less than the applicable limit, boration must be initiated immediately.

ITS 3.1.1 ACTION states when SDM is not within limits, boration must be initiated within 15 minutes. This changes the CTS by relaxing the Completion Time from "immediately" to 15 minutes.

The purpose of CTS 3.1.1.1 ACTION is to restore the SDM to within its limit promptly. This change is acceptable because the Completion Time is consistent with safe operation under the specific Condition, considering the operability status of the redundant systems of required features, the capacity and capability of remaining features, and the low probability of a DBA occurring during the allowed Completion Time. This ITS Completion Time of 15 minutes is adequate for an operator to correctly align and start the required systems and components.

In addition, the ITS Bases for the ACTION states that boration must be initiated promptly. This change is designated as less restrictive because additional time is allowed to restore parameters to within the LCO limits than was allowed in the CTS.

L02 (Category 4 - Relaxation of Required Action) CTS 3.1.1.1 ACTION states when the SDM is less than or equal to 1.6% k/k, boration must be initiated and continued at greater than or equal to 35 gpm of a solution containing greater than or equal to 6120 ppm boron or equivalent until the required SDM is restored.

ITS 3.1.1 ACTION A states that when the SDM is not within limits to initiate boration to restore SDM to within limits. This changes the CTS by eliminating the specific values of flow rate and the boron concentration used to restore compliance with the LCO.

The purpose of CTS 3.1.1.1 ACTION is to restore the SDM to within its limit.

This change is acceptable because the Required Actions are used to establish remedial measures that must be taken in response to the degraded conditions in order to minimize risk associated with continued operation while providing time to repair inoperable features. The Required Actions are consistent with safe operation under the specified Condition, considering the operability status of the Sequoyah Unit 1 and Unit 2 Page 4 of 5 Enclosure 2, Volume 6, Rev. 0, Page 14 of 356

Enclosure 2, Volume 6, Rev. 0, Page 15 of 356 DISCUSSION OF CHANGES ITS 3.1.1, SHUTDOWN MARGIN (SDM) specified redundant systems of required features, the capacity and capability of remaining features, a reasonable time for repairs or replacement of required features, and the low probability of a DBA occurring during the allowed Completion Time. Removing the specific values of flow rate and boron concentration from the CTS ACTION provides flexibility in the restoration of the SDM and eliminates conflicts between the SDM value and the specific boration values in the CTS ACTION. As stated, in the ITS Bases for ACTION A, "In the determination of the required combination of boration flow rate and boron concentration, there is no unique requirement that must be satisfied. Since it is imperative to raise the boron concentration of the RCS as soon as possible, the boron concentration should be a highly concentrated solution, such as that normally found in the boric acid tank, or the refueling water storage tank. The operator should borate with the best source available for the plant conditions."

Specifying a minimum flow rate and concentration in the ACTION may not accomplish the objective of raising the RCS boron concentration as soon as possible. This change is designated as less restrictive because less stringent Required Actions are being applied in the ITS than were applied in the CTS.

L03 (Category 5 - Deletion of Surveillance Requirement) CTS 4.1.1.1.1.d requires verification that the SDM is within limit, "Prior to initial operation above 5%

RATED THERMAL POWER after each fuel loading, by consideration of the factors of e below (CTS 4.1.1.1.1.e), with the control banks at the maximum insertion limit of Specification 3.1.3.6." The ITS does not contain a similar requirement. This changes the CTS by deleting Surveillance Requirement 4.1.1.1.1.d.

The purpose of CTS 4.1.1.1.1.d is to verify core design predictions by determining the SDM with the control rods at the insertion limits. This change is acceptable because the deleted Surveillance Requirement is not necessary to verify the LCO is within limit. The core design predictions, such as rod worth, boron worth, and critical boron concentration, are verified in a manner and at a Frequency necessary to give confidence that these predicted values are within limit in accordance with ITS SR 3.1.2.1. ITS SR 3.1.2.1 has a conditional Frequency similar to that of CTS 4.1.1.1.d requiring performance once prior to entering MODE 1 (> 5% RTP) after each refueling. To ensure the SDM is within limits during reactor startup the critical boron concentration is verified during the startup physics test program and prior to criticality per ITS SR 3.1.6.1 (Estimated Critical Position). Thereafter SDM is confirmed by performance of ITS SR 3.1.4.1 (Rod Alignment), SR 3.1.5.1(Shutdown Bank Rod Insertion Limits),

and SR 3.1.6.2 (Control Bank Rod Insertion Limits). Thus, the SDM continues to be verified in a manner and at a Frequency necessary to give confidence that the parameter is within limit. Therefore, the core design parameters upon which SDM relies are verified before exceeding 5% RATED THERMAL POWER after each refueling outage. This change is designated as less restrictive because Surveillances which are required in the CTS will not be required in the ITS.

Sequoyah Unit 1 and Unit 2 Page 5 of 5 Enclosure 2, Volume 6, Rev. 0, Page 15 of 356

Enclosure 2, Volume 6, Rev. 0, Page 16 of 356 Improved Standard Technical Specifications (ISTS) Markup and Justification for Deviations (JFDs)

Enclosure 2, Volume 6, Rev. 0, Page 16 of 356

Enclosure 2, Volume 6, Rev. 0, Page 17 of 356 CTS SDM 3.1.1 3.1 REACTIVITY CONTROL SYSTEMS 3.1.1 SHUTDOWN MARGIN (SDM) 3.1.1.1, LCO 3.1.1 SDM shall be within the limits specified in the COLR.

3.1.1.2 3.1.1.1 Applicability, APPLICABILITY: MODE 2 with keff < 1.0, 3.1.1.2 MODES 3, 4, and 5.

Applicability ACTIONS CONDITION REQUIRED ACTION COMPLETION TIME 3.1.1.1 ACTION, A. SDM not within limits. A.1 Initiate boration to restore 15 minutes 3.1.1.2 SDM to within limits.

ACTION SURVEILLANCE REQUIREMENTS SURVEILLANCE FREQUENCY 4.1.1.1.1.e, SR 3.1.1.1 Verify SDM to be within the limits specified in the [ 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months 4.1.1.2.b COLR. 1 OR In accordance with the Surveillance Frequency Control Program ] 1 SEQUOYAH UNIT 1 Amendment XXX Westinghouse STS 3.1.1-1 Rev. 4.0 2 Enclosure 2, Volume 6, Rev. 0, Page 17 of 356

Enclosure 2, Volume 6, Rev. 0, Page 18 of 356 CTS SDM 3.1.1 3.1 REACTIVITY CONTROL SYSTEMS 3.1.1 SHUTDOWN MARGIN (SDM) 3.1.1.1, LCO 3.1.1 SDM shall be within the limits specified in the COLR.

3.1.1.2 3.1.1.1 Applicability, APPLICABILITY: MODE 2 with keff < 1.0, 3.1.1.2 MODES 3, 4, and 5.

Applicability ACTIONS CONDITION REQUIRED ACTION COMPLETION TIME 3.1.1.1 ACTION, A. SDM not within limits. A.1 Initiate boration to restore 15 minutes 3.1.1.2 SDM to within limits.

ACTION SURVEILLANCE REQUIREMENTS SURVEILLANCE FREQUENCY 4.1.1.1.1.e, SR 3.1.1.1 Verify SDM to be within the limits specified in the [ 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months 4.1.1.2.b COLR. 1 OR In accordance with the Surveillance Frequency Control Program ] 1 SEQUOYAH UNIT 2 Amendment XXX Westinghouse STS 3.1.1-1 Rev. 4.0 2 Enclosure 2, Volume 6, Rev. 0, Page 18 of 356

Enclosure 2, Volume 6, Rev. 0, Page 19 of 356 JUSTIFICATION FOR DEVIATIONS ITS 3.1.1, SHUTDOWN MARGIN

1. ISTS SR 3.1.1.1 provides two options for controlling the Frequencies of Surveillance Requirements. SQN is proposing to control the Surveillance Frequencies under the Surveillance Frequency Control Program.

2. Changes are made (additions, deletions, and/or changes) to the ISTS that reflect the plant specific nomenclature, number, reference, system description, analysis, or licensing basis description.

Sequoyah Unit 1 and Unit 2 Page 1 of 1 Enclosure 2, Volume 6, Rev. 0, Page 19 of 356

Enclosure 2, Volume 6, Rev. 0, Page 20 of 356 Improved Standard Technical Specifications (ISTS) Bases Markup and Bases Justification for Deviations (JFDs)

Enclosure 2, Volume 6, Rev. 0, Page 20 of 356

Enclosure 2, Volume 6, Rev. 0, Page 21 of 356 SDM B 3.1.1 B 3.1 REACTIVITY CONTROL SYSTEMS B 3.1.1 SHUTDOWN MARGIN (SDM)

BASES BACKGROUND According to GDC 26 (Ref. 1), the reactivity control systems must be redundant and capable of holding the reactor core subcritical when shut down under cold conditions. Maintenance of the SDM ensures that postulated reactivity events will not damage the fuel.

SDM requirements provide sufficient reactivity margin to ensure that acceptable fuel design limits will not be exceeded for normal shutdown and anticipated operational occurrences (AOOs). As such, the SDM defines the degree of subcriticality that would be obtained immediately following the insertion or scram of all shutdown and control rods, assuming that the single rod cluster assembly of highest reactivity worth is fully withdrawn.

The system design requires that two independent reactivity control systems be provided, and that one of these systems be capable of maintaining the core subcritical under cold conditions. These requirements are provided by the use of movable control assemblies and soluble boric acid in the Reactor Coolant System (RCS). The Control Rod System can compensate for the reactivity effects of the fuel and water temperature changes accompanying power level changes over the range from full load to no load. In addition, the Control Rod System, together with the boration system, provides the SDM during power operation and is capable of making the core subcritical rapidly enough to prevent exceeding acceptable fuel damage limits, assuming that the rod of highest reactivity worth remains fully withdrawn. The soluble boron system can compensate for fuel depletion during operation and all xenon burnout reactivity changes and maintain the reactor subcritical under cold conditions.

During power operation, SDM control is ensured by operating with the shutdown banks fully withdrawn and the control banks within the limits of LCO 3.1.6, "Control Bank Insertion Limits." When the unit is in the shutdown and refueling modes, the SDM requirements are met by means of adjustments to the RCS boron concentration.

APPLICABLE The minimum required SDM is assumed as an initial condition in safety SAFETY analyses. The safety analysis (Ref. 2) establishes an SDM that ensures 2 ANALYSES specified acceptable fuel design limits are not exceeded for normal operation and AOOs, with the assumption of the highest worth rod stuck out on scram. For MODE 5, the primary safety analysis that relies on the SDM limits is the boron dilution analysis.

SEQUOYAH UNIT 1 Revision XXX Westinghouse STS B 3.1.1-1 Rev. 4.0 1 Enclosure 2, Volume 6, Rev. 0, Page 21 of 356

Enclosure 2, Volume 6, Rev. 0, Page 22 of 356 SDM B 3.1.1 BASES APPLICABLE SAFETY ANALYSES (continued)

The acceptance criteria for the SDM requirements are that specified acceptable fuel design limits are maintained. This is done by ensuring that:

a. The reactor can be made subcritical from all operating conditions, transients, and Design Basis Events,

b. The reactivity transients associated with postulated accident conditions are controllable within acceptable limits (departure from nucleate boiling ratio (DNBR), fuel centerline temperature limits for AOOs, and 280 cal/gm energy deposition for the rod ejection accident), and

c. The reactor will be maintained sufficiently subcritical to preclude inadvertent criticality in the shutdown condition.

The most limiting accident for the SDM requirements is based on a main steam line break (MSLB), as described in the accident analysis (Ref. 2).

The increased steam flow resulting from a pipe break in the main steam system causes an increased energy removal from the affected steam generator (SG), and consequently the RCS. This results in a reduction of the reactor coolant temperature. The resultant coolant shrinkage causes a reduction in pressure. In the presence of a negative moderator temperature coefficient, this cooldown causes an increase in core reactivity. As RCS temperature decreases, the severity of an MSLB decreases until the MODE 5 value is reached. The most limiting MSLB, with respect to potential fuel damage before a reactor trip occurs, is a 1 guillotine break of a main steam line inside containment initiated at the end of core life. The positive reactivity addition from the moderator double ended temperature decrease will terminate when the affected SG boils dry, thus terminating RCS heat removal and cooldown. Following the MSLB, a post trip return to power may occur; however, no fuel damage occurs as a result of the post trip return to power, and THERMAL POWER does not violate the Safety Limit (SL) requirement of SL 2.1.1.

s In addition to the limiting MSLB transient, the SDM requirement must also 2 protect against:

a. Inadvertent boron dilution,

b. An uncontrolled rod withdrawal from subcritical or low power condition, SEQUOYAH UNIT 1 Revision XXX Westinghouse STS B 3.1.1-2 Rev. 4.0 1 Enclosure 2, Volume 6, Rev. 0, Page 22 of 356

Enclosure 2, Volume 6, Rev. 0, Page 23 of 356 SDM B 3.1.1 BASES APPLICABLE SAFETY ANALYSES (continued)

c. Startup of an inactive reactor coolant pump (RCP), and

d. Rod ejection.

Each of these events is discussed below.

In the boron dilution analysis, the required SDM defines the reactivity difference between an initial subcritical boron concentration and the corresponding critical boron concentration. These values, in conjunction with the configuration of the RCS and the assumed dilution flow rate, directly affect the results of the analysis. This event is most limiting at the beginning of core life, when critical boron concentrations are highest.

Depending on the system initial conditions and reactivity insertion rate, the uncontrolled rod withdrawal transient is terminated by either a high an overtemperature power level trip or a high pressurizer pressure trip. In all cases, power 1 T level, RCS pressure, linear heat rate, and the DNBR do not exceed allowable limits.

The startup of an inactive RCP will not result in a "cold water" criticality, even if the maximum difference in temperature exists between the SG and the core. The maximum positive reactivity addition that can occur due to an inadvertent RCP start is less than half the minimum required SDM. Startup of an idle RCP cannot, therefore, produce a return to power from the hot standby condition.

The ejection of a control rod rapidly adds reactivity to the reactor core, causing both the core power level and heat flux to increase with corresponding increases in reactor coolant temperatures and pressure.

The ejection of a rod also produces a time dependent redistribution of core power.

SDM satisfies Criterion 2 of 10 CFR 50.36(c)(2)(ii). Even though it is not directly observed from the control room, SDM is considered an initial condition process variable because it is periodically monitored to ensure that the unit is operating within the bounds of accident analysis assumptions.

LCO SDM is a core design condition that can be ensured during operation through control rod positioning (control and shutdown banks) and through the soluble boron concentration.

SEQUOYAH UNIT 1 Revision XXX Westinghouse STS B 3.1.1-3 Rev. 4.0 1 Enclosure 2, Volume 6, Rev. 0, Page 23 of 356

Enclosure 2, Volume 6, Rev. 0, Page 24 of 356 SDM B 3.1.1 BASES LCO (continued)

The MSLB (Ref. 2) and the boron dilution (Ref. 3) accidents are the most limiting analyses that establish the SDM value of the LCO. For MSLB accidents, if the LCO is violated, there is a potential to exceed the DNBR limit and to exceed 10 CFR 100, "Reactor Site Criteria," limits (Ref. 4).

For the boron dilution accident, if the LCO is violated, the minimum required time assumed for operator action to terminate dilution may no longer be applicable.

APPLICABILITY In MODE 2 with keff < 1.0 and in MODES 3, 4, and 5, the SDM requirements are applicable to provide sufficient negative reactivity to meet the assumptions of the safety analyses discussed above. In MODE 6, the shutdown reactivity requirements are given in LCO 3.9.1, "Boron Concentration." In MODES 1 and 2, SDM is ensured by complying with LCO 3.1.5, "Shutdown Bank Insertion Limits," and LCO 3.1.6.

ACTIONS A.1 If the SDM requirements are not met, boration must be initiated promptly.

A Completion Time of 15 minutes is adequate for an operator to correctly align and start the required systems and components. It is assumed that boration will be continued until the SDM requirements are met.

In the determination of the required combination of boration flow rate and boron concentration, there is no unique requirement that must be satisfied. Since it is imperative to raise the boron concentration of the RCS as soon as possible, the boron concentration should be a highly concentrated solution, such as that normally found in the boric acid refueling storage tank, or the borated water storage tank. The operator should 1 borate with the best source available for the plant conditions.

In determining the boration flow rate, the time in core life must be considered. For instance, the most difficult time in core life to increase the RCS boron concentration is at the beginning of cycle when the boron concentration may approach or exceed 2000 ppm. Assuming that a value 50 (1000 pcm) of 1% k/k must be recovered and a boration flow rate of [ ] gpm, it is 3

possible to increase the boron concentration of the RCS by 100 ppm in INSERT 1 approximately 35 minutes. If a boron worth of 10 pcm/ppm is assumed, this combination of parameters will increase the SDM by 1% k/k. These boration parameters of [ ] gpm and [ ] ppm represent typical values and are provided for the purpose of offering a specific example.

SEQUOYAH UNIT 1 Revision XXX Westinghouse STS B 3.1.1-4 Rev. 4.0 1 Enclosure 2, Volume 6, Rev. 0, Page 24 of 356

Enclosure 2, Volume 6, Rev. 0, Page 25 of 356 B 3.1.1 1

INSERT 1 147 ppm in approximately 46 minutes. If a boron worth of 6.8 pcm/ppm is assumed, this combination will increase the SDM by 1% k/k or 1000 pcm. These boration parameters represent Sequoyah typical values and are provided for the purpose of offering a specific example.

Insert Page B 3.1.1-4 Enclosure 2, Volume 6, Rev. 0, Page 25 of 356

Enclosure 2, Volume 6, Rev. 0, Page 26 of 356 SDM B 3.1.1 BASES SURVEILLANCE SR 3.1.1.1 REQUIREMENTS In MODES 1 and 2 with Keff 1.0, SDM is verified by observing that the 2 requirements of LCO 3.1.5 and LCO 3.1.6 are met. In the event that a rod is known to be untrippable, however, SDM verification must account for the worth of the untrippable rod as well as another rod of maximum worth.

MODE 2 with keff < 1.0 and in In MODES 3, 4, and 5, the SDM is verified by performing a reactivity 6 balance calculation, considering the listed reactivity effects:

a. RCS boron concentration,

b. Control bank position,

c. RCS average temperature,

d. Fuel burnup based on gross thermal energy generation,

e. Xenon concentration,

f. Samarium concentration, and

g. Isothermal temperature coefficient (ITC).

Using the ITC accounts for Doppler reactivity in this calculation because the reactor is subcritical, and the fuel temperature will be changing at the same rate as the RCS.

[ The Frequency of 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months is based on the generally slow change in required boron concentration and the low probability of an accident occurring without the required SDM. This allows time for the operator to collect the required data, which includes performing a boron 4 concentration analysis, and complete the calculation.

OR The Surveillance Frequency is controlled under the Surveillance Frequency Control Program.

REVIEWERS NOTE-----------------------------------

Plants controlling Surveillance Frequencies under a Surveillance Frequency Control Program should utilize the appropriate Frequency 5 description, given above, and the appropriate choice of Frequency in the Surveillance Requirement.

] 4 SEQUOYAH UNIT 1 Revision XXX Westinghouse STS B 3.1.1-5 Rev. 4.0 1 Enclosure 2, Volume 6, Rev. 0, Page 26 of 356

Enclosure 2, Volume 6, Rev. 0, Page 27 of 356 SDM B 3.1.1 BASES REFERENCES 1. 10 CFR 50, Appendix A, GDC 26.

Section 15.4.2

2. FSAR, Chapter [15]. 1 3 U Section 15.2.4

3. FSAR, Chapter [15]. 1 3

4. 10 CFR 100.

SEQUOYAH UNIT 1 Revision XXX Westinghouse STS B 3.1.1-6 Rev. 4.0 1 Enclosure 2, Volume 6, Rev. 0, Page 27 of 356

Enclosure 2, Volume 6, Rev. 0, Page 28 of 356 SDM B 3.1.1 B 3.1 REACTIVITY CONTROL SYSTEMS B 3.1.1 SHUTDOWN MARGIN (SDM)

BASES BACKGROUND According to GDC 26 (Ref. 1), the reactivity control systems must be redundant and capable of holding the reactor core subcritical when shut down under cold conditions. Maintenance of the SDM ensures that postulated reactivity events will not damage the fuel.

SDM requirements provide sufficient reactivity margin to ensure that acceptable fuel design limits will not be exceeded for normal shutdown and anticipated operational occurrences (AOOs). As such, the SDM defines the degree of subcriticality that would be obtained immediately following the insertion or scram of all shutdown and control rods, assuming that the single rod cluster assembly of highest reactivity worth is fully withdrawn.

The system design requires that two independent reactivity control systems be provided, and that one of these systems be capable of maintaining the core subcritical under cold conditions. These requirements are provided by the use of movable control assemblies and soluble boric acid in the Reactor Coolant System (RCS). The Control Rod System can compensate for the reactivity effects of the fuel and water temperature changes accompanying power level changes over the range from full load to no load. In addition, the Control Rod System, together with the boration system, provides the SDM during power operation and is capable of making the core subcritical rapidly enough to prevent exceeding acceptable fuel damage limits, assuming that the rod of highest reactivity worth remains fully withdrawn. The soluble boron system can compensate for fuel depletion during operation and all xenon burnout reactivity changes and maintain the reactor subcritical under cold conditions.

During power operation, SDM control is ensured by operating with the shutdown banks fully withdrawn and the control banks within the limits of LCO 3.1.6, "Control Bank Insertion Limits." When the unit is in the shutdown and refueling modes, the SDM requirements are met by means of adjustments to the RCS boron concentration.

APPLICABLE The minimum required SDM is assumed as an initial condition in safety SAFETY analyses. The safety analysis (Ref. 2) establishes an SDM that ensures 2 ANALYSES specified acceptable fuel design limits are not exceeded for normal operation and AOOs, with the assumption of the highest worth rod stuck out on scram. For MODE 5, the primary safety analysis that relies on the SDM limits is the boron dilution analysis.

SEQUOYAH UNIT 2 Revision XXX Westinghouse STS B 3.1.1-1 Rev. 4.0 1 Enclosure 2, Volume 6, Rev. 0, Page 28 of 356

Enclosure 2, Volume 6, Rev. 0, Page 29 of 356 SDM B 3.1.1 BASES APPLICABLE SAFETY ANALYSES (continued)

The acceptance criteria for the SDM requirements are that specified acceptable fuel design limits are maintained. This is done by ensuring that:

a. The reactor can be made subcritical from all operating conditions, transients, and Design Basis Events,

b. The reactivity transients associated with postulated accident conditions are controllable within acceptable limits (departure from nucleate boiling ratio (DNBR), fuel centerline temperature limits for AOOs, and 280 cal/gm energy deposition for the rod ejection accident), and

c. The reactor will be maintained sufficiently subcritical to preclude inadvertent criticality in the shutdown condition.

The most limiting accident for the SDM requirements is based on a main steam line break (MSLB), as described in the accident analysis (Ref. 2).

The increased steam flow resulting from a pipe break in the main steam system causes an increased energy removal from the affected steam generator (SG), and consequently the RCS. This results in a reduction of the reactor coolant temperature. The resultant coolant shrinkage causes a reduction in pressure. In the presence of a negative moderator temperature coefficient, this cooldown causes an increase in core reactivity. As RCS temperature decreases, the severity of an MSLB decreases until the MODE 5 value is reached. The most limiting MSLB, with respect to potential fuel damage before a reactor trip occurs, is a 1 guillotine break of a main steam line inside containment initiated at the end of core life. The positive reactivity addition from the moderator double ended temperature decrease will terminate when the affected SG boils dry, thus terminating RCS heat removal and cooldown. Following the MSLB, a post trip return to power may occur; however, no fuel damage occurs as a result of the post trip return to power, and THERMAL POWER does not violate the Safety Limit (SL) requirement of SL 2.1.1.

s In addition to the limiting MSLB transient, the SDM requirement must also 2 protect against:

a. Inadvertent boron dilution,

b. An uncontrolled rod withdrawal from subcritical or low power condition, SEQUOYAH UNIT 2 Revision XXX Westinghouse STS B 3.1.1-2 Rev. 4.0 1 Enclosure 2, Volume 6, Rev. 0, Page 29 of 356

Enclosure 2, Volume 6, Rev. 0, Page 30 of 356 SDM B 3.1.1 BASES APPLICABLE SAFETY ANALYSES (continued)

c. Startup of an inactive reactor coolant pump (RCP), and

d. Rod ejection.

Each of these events is discussed below.

In the boron dilution analysis, the required SDM defines the reactivity difference between an initial subcritical boron concentration and the corresponding critical boron concentration. These values, in conjunction with the configuration of the RCS and the assumed dilution flow rate, directly affect the results of the analysis. This event is most limiting at the beginning of core life, when critical boron concentrations are highest.

Depending on the system initial conditions and reactivity insertion rate, the uncontrolled rod withdrawal transient is terminated by either a high an overtemperature power level trip or a high pressurizer pressure trip. In all cases, power 1 T level, RCS pressure, linear heat rate, and the DNBR do not exceed allowable limits.

The startup of an inactive RCP will not result in a "cold water" criticality, even if the maximum difference in temperature exists between the SG and the core. The maximum positive reactivity addition that can occur due to an inadvertent RCP start is less than half the minimum required SDM. Startup of an idle RCP cannot, therefore, produce a return to power from the hot standby condition.

The ejection of a control rod rapidly adds reactivity to the reactor core, causing both the core power level and heat flux to increase with corresponding increases in reactor coolant temperatures and pressure.

The ejection of a rod also produces a time dependent redistribution of core power.

SDM satisfies Criterion 2 of 10 CFR 50.36(c)(2)(ii). Even though it is not directly observed from the control room, SDM is considered an initial condition process variable because it is periodically monitored to ensure that the unit is operating within the bounds of accident analysis assumptions.

LCO SDM is a core design condition that can be ensured during operation through control rod positioning (control and shutdown banks) and through the soluble boron concentration.

SEQUOYAH UNIT 2 Revision XXX Westinghouse STS B 3.1.1-3 Rev. 4.0 1 Enclosure 2, Volume 6, Rev. 0, Page 30 of 356

Enclosure 2, Volume 6, Rev. 0, Page 31 of 356 SDM B 3.1.1 BASES LCO (continued)