NL-07-0731, Application for Technical Specification Improvement to Revise Control Rod Scram Time Testing Frequency

Application for Technical Specification Improvement to Revise Control Rod Scram Time Testing Frequency

ML071560598
Person / Time
Site:	Hatch
Issue date:	06/05/2007
From:	Stinson L Southern Nuclear Operating Co
To:	Document Control Desk, NRC/NRR/ADRO
References
NL-07-0731
Download: ML071560598 (22)

Text

1. M. Stinson (Mike) Southern Nuclear Vice President Operating Company, lnc.

Fleet Operations Support 40 lnverness Center Parkway Post Office Box 1295 Birmingham. Alabama 35201 Te1205.992.5181 Fax 205.992.0341 SOUTHERN COMPW A

June 5, 2007 Energy to Serve YourWorlds" Docket Nos.: 50-321 50-366 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D. C. 20555-0001 Edwin 1. Hatch Nuclear Plant Application for Technical Specification Improvement to Revise Control Rod Scram Time Testing Frequency Ladies and Gentlemen:

In accordance with the provisions of Section 50.90 of Title 10 of the Code of Federal Regulations, Southern Nuclear Operating Company (SNC) is submitting a request for an amendment to the Technical Specifications (TS) for Plant Hatch, Units 1 and 2.

The proposed amendment would revise the TS testing frequency for the surveillance requirement (SR) in TS 3.1.4, "Control Rod Scram Times." These changes are based on TS Task Force (TSTF) change traveler TSTF-460, that has been approved generically for the boiling water reactor (BWR) Standard TS, NUREG-1433 (BWRl4). The frequency of SR 3.1.4.2, control rod scram time testing, is revised from "1 20 days cumulative operation in MODE 1" to "200 days cumulative operation in MODE 1 ." A notice announcing the availability of this proposed TS change using the consolidated line item improvement process (CLIIP) was published in the Federal Register on August 23,2004 (69 FR 5 1854).

Enclosure 1 provides a description of the proposed change and the confirmation of applicability. Enclosure 2 provides the markup of the existing TS and Bases pages, and Enclosure 3 provides the clean typed pages.

Since this involves a CLIIP, SNC requests approval of the proposed license amendment by December 15,2008, with the amendment being implemented within 30 days of issuance.

(Affirmation and signature provided on the following page.)

U. S. Nuclear Regulatory Commission N L-07-073 1 Page 2 Mr. L. M. Stinson states he is a Vice President of Southern Nuclear Operating Company, is authorized to execute this oath on behalf of Southern Nuclear Operating Company and to the best of his knowledge and belief, the facts set forth in this letter are true.

NRC commitments are provided in Enclosure 4. If you have any questions, please advise.

Respectfully submitted, SOUTHERN NUCLEAR OPERATING COMPANY

, ...._ L. M. Stinson

< b' Vice President Fleet Operations Support

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Enclosures:

1 . Description and Verification of Applicability

2. Proposed Technical Specifications and Bases Marked-up Pages

3. Clean Typed Technical Specifications and Bases Pages

4. List of Regulatory Commitment cc: Southern Nuclear Operating Com~any Mr. J. T. Gasser, Executive Vice President Mr. D. R. Madison, Vice President - Hatch Mr. D. H. Jones, Vice President - Engineering RType: CHA02.004 U. S. Nuclear Regulatory Commission Dr. W. D. Travers, Regional Administrator Mr. R. E. Martin, NRR Project Manager - Hatch Mr. D. S. Simpkins, Senior Resident Inspector - Hatch State of Georgia Mr. N. Holcomb, Commissioner - Department of Natural Resources

Enclosure 1 Edwin I. Hatch Nuclear Plant, Units 1 and 2 Technical Specifications Amendment request to Revise Control Rod Scram Time Testing Surveillance Frequency Description and Verification of Applicability

Enclosure 1 Edwin I. Hatch Nuclear Plant, Units 1 and 2 Technical Specifications Amendment request to Revise Control Rod Scram Time Testing Surveillance Frequency Description and Verification of Applicability 1.0 Introduction The proposed license amendment revises the required testing frequency for the surveillance requirement (SR) in Technical Specification (TS) 3.1.4, "Control Rod Scram Times." A notice announcing the availability of this proposed TS change using the consolidated line item improvement process (CLIIP) was published in the Federal Register on August 23,2004.

2.0 Proposed Change These changes are based on TS Task Force (TSTF) change traveler TSTF-460 (Revision 0), that has been approved generically for the boiling water reactor (BWR) Standard TS, NUREG-1433 (BWW4). The required frequency of SR 3.1.4.2 is changed from "120 days cumulative operation in MODE 1" to "200 days cumulative operation in MODE 1."

3.0 Background

The background for this application is adequately addressed by the CLIP Notice of Availability published on August 23,2004 (69 FR 5 1854) and TSTF-460.

4.0 Technical Analysis Southern Nuclear has reviewed the safety analysis (SE) published on August 23,2004 (69 FR 5 1854) as part of the CLIP Notice of Availability. This verification included a review of the NRC staffs SE and the supporting information provided to support TSTF-460. Southern Nuclear has concluded that the justifications presented in the TSTF proposal and the SE prepared by the NRC staff are applicable to Plant Hatch, Units 1 and 2, and justify this amendment for the incorporation of the changes to the Hatch Plant Technical Specifications.

As described in the CLIIP model SE, part of the justification for the change in surveillance frequency is the high reliability of the Plant Hatch Control Rod Drive System. As requested in the Notice of Availability published on August 23,2004 (69 FR 5 1854), the historical performance of the Control Rod Drive system at Plant Hatch is as follows:

The Hatch Units 1 and 2 cores each contain 137 control rods with the full-in position being 00 and full-out being 48.

The Hatch Unit 1 and 2 Technical Specifications are consistent with the BWW4 Standard Technical Specifications (TS). The scram time TS requirements are as follows:

Enclosure 1 Edwin I. Hatch Nuclear Plant, Units 1 and 2 Technical Specifications Amendment request to Revise Control Rod Scram Time Testing Surveillance Frequency Description and Verification of Applicability Surveillance Requirement (SR) 3.1.3.4 of Limiting Condition for Operation (LCO) 3.1.3, "Control Rod Operability" requires that each control rod have a scram time less than or equal to seven seconds to notch position 06, from the full-out position of 48.

This is an Operability requirement for each control rod. Consequently, a scram time of greater than seven seconds to notch 06 requires declaring the control rod inoperable.

Additionally, TS LC0 3.1.4, "Control Rod Scram Times," requires that no more than 10 Operable control rods be slow and that no more than 2 "slow" Operable control rods occupy adjacent locations.

A slow control rod is one which does not meet one of the following scram time criteria:

0.44 seconds to notch 46, 1.08 seconds to notch 36, 1.83 seconds to notch 26 and 3.35 seconds to notch 06.

Scram time testing at Hatch is performed for each control rod at the beginning of each operating cycle (BOC) per TS SR 3.1.4.1, and for 10% of the control rods after every 120 days of cumulative operation in MODE 1 per SR 3.1.4.2. Also, a control rod must be scram time tested after work on the control rod or on the control rod drive that could affect its scram time per SRs 3.1.4.3 and 3.1.4.4. Most scram time tests are required to be performed at reactor pressures greater than or equal to 800 psig. However, SR 3.1.4.3 requires a scram time test for control rods following maintenance before the rod may be declared Operable, therefore, it provides for testing at pressures less than 800 psig. In those cases, only notch 06 limits apply, and the acceptance criterion is adjusted for the low pressure.

Individual control rod scrams are performed to test the rods at the beginning of each cycle. For the 120 day test, individual rod tests are performed as well. However, control rods are usually configured into a scram time recorder so that, if a reactor scram were to occur, scram data could be obtained and used to satisfy SR 3.1.4.2. This would not necessarily result in a test of all 137 control rods since during the majority of the operating cycle, some control rods are only partially withdrawn. Individual rod scrams are used to satisfy the requirements of SR 3.1.4.3 and 3.1.4.4 following control rod or drive maintenance.

Hatch scram time testing data packages were reviewed for the years 2002 to the beginning of cycle in 2006 for Unit 1 and 2003 to the beginning of cycle in 2007 for Unit

2. Included are the results of the complete beginning of cycle scram time data for Unit 1 cycles 21, 22, and 23, and for Unit 2 cycles 18, 19, and 20.

The below data demonstrates the reliability of the Hatch Units 1 and 2 Control Rod Drive system with respect to scram times. This data represents a total of 1920 individual

Enclosure 1 Edwin I. Hatch Nuclear Plant, Units 1 and 2 Technical Specifications Amendment request to Revise Control Rod Scram Time Testing Surveillance Frequency Description and Verification of Applicability control rod scram tests (1005 for Unit 1 and 915 for Unit 2) with no rods inoperable and only 2 slow rods. These data also indicate that Hatch should have no problem meeting the more restrictive 7.5%slow rod criteria required by the CLIIP.

In April of 2002, one control rod was tested following a control rod drive repair. The rod met its acceptance criterion. Also in April of 2002, 137 control rods were tested. All rods met the seven second criteria and no rods were slow.

Again in April of 2002,88 control rods were tested. All rods met the seven second criteria and no rods were slow.

In July of 2002, 17 control rods were tested. All rods met the seven second criteria and no rods were slow.

In December of 2002, 17 control rods were tested. All rods met the seven second criteria ands no rods were slow.

In February of 2003, 19 control rods were tested. All rods met the seven second criteria and no rods were slow.

In April of 2003,96 control rods were tested. All rods met the seven second criteria and no rods were slow.

In August of 2003, 16 control rods were tested. All rods met the seven second criteria and no rods were slow.

In November of 2003, 15 control rods were tested. All rods met the seven second criteria and no rods were slow.

In March of 2004, 137 control rods were tested. All rods met the seven second criteria and no rods were slow.

Also in March of 2004,2 control rods were tested following maintenance. Both rods met their low and high pressure acceptance criteria.

In June of 2004, 16 control rods were tested. All rods met the seven second criteria and no rods were slow.

In August of 2004, 16 control rods were tested. All rods met the seven second criteria and no rods were slow.

Enclosure 1 Edwin I. Hatch Nuclear Plant, Units 1 and 2 Technical Specifications Amendment request to Revise Control Rod Scram Time Testing Surveillance Frequency Description and Verification of Applicability In November of 2004, 19 control rods were tested. All rods met the seven second criteria and no rods were slow.

In January of 2005,93 control rods were tested. All rods met the seven second criteria and no rods were slow.

In April of 2005,18 control rods were tested. All rods met the seven second criteria and no rods were slow.

In July of 2005, 16 control rods were tested. All rods met the seven second criteria and no rods were slow.

In October of 2005, 16 control rods were tested. All rods met the seven second criteria and no rods were slow.

In October of 2005, 129 control rods were tested. All rods met the seven second criteria and no rods were slow.

In March of 2006, 137 control rods were tested. All rods met the seven second criteria and no rods were slow.

Unit 2 In March of 2003, 137 control rods were scram time tested. All rods met the seven second criteria and no rods were slow.

In August of 2003, 16 rods were tested. All rods met the seven second criteria and no rods were slow.

In June of 2003,18 control rods were tested. All rods met the seven second criteria and no rods were slow.

In November of 2003, 16 control rods were tested. All rods met the seven second criteria and no rods were slow.

In February of 2004, 16 control rods were tested. All rods met the seven second criteria and no rods were slow.

In April of 2004, 15 control rods were tested. All rods met the seven second criteria and no rods were slow.

Enclosure 1 Edwin I. Hatch Nuclear Plant, Units 1 and 2 Technical Specifications Amendment request to Revise Control Rod Scram Time Testing Surveillance Frequency Description and Verification of Applicability In July of 2004, 16 control rods were tested. All rods met the seven second criteria and no rods were slow.

In September of 2004, 1 1 1 control rods were tested. All rods met the seven second criteria and no rods were slow.

Also in September of 2004, 1 control rod was tested at low pressure. It met its acceptance criterion.

In October of 2004, 1 control rod was tested. It met its seven second criteria and it was not slow.

In March of 2005, 1 control rod was tested at low pressure following maintenance. The rod met its acceptance criterion.

Also in March of 2005, 137 control rods were tested. All rods met the seven second criteria and one rod was declared slow.

Again in March of 2005, 116 control rods were tested. All rods met the seven second criteria and no rods were slow.

In April of 2005, 1 control rod was tested. It met its seven second criteria and was not slow.

In May of 2005, 1 control rod was tested. The rod that had been declared slow in the March of 2005 testing was re-tested and passed all the acceptance criteria.

In August of 2005, 17 control rods were tested. All rods met the seven second criteria and no rods were slow.

In November of 2005, 16 control rods were tested. All rods met the seven second criteria and one rod was declared slow.

In February of 2006, 16 control rods were tested. All rods met the seven second criteria and no rods were slow.

In April of 2006, 111 control rods were tested. All rods met the seven second criteria and no rods were slow.

In August of 2006, 15 control rods were tested. All rods met the seven second criteria and no rods were slow.

Enclosure 1 Edwin I. Hatch Nuclear Plant, Units 1 and 2 Technical Specifications Amendment request to Revise Control Rod Scram Time Testing Surveillance Frequency Description and Verification of Applicability In March of 2007, 137 control rods were tested. All rods met the seven second criteria and no rods were slow.

At the beginning of Unit 2 cycle 20 (March 2007) 12 Westinghouse control rod blades were loaded in the core. Westinghouse type blades are not included in the listed scram time data before March of 2007. These 12 blades were successfully tested, however, in the beginning of cycle 20 testing for Hatch Unit 2 in March of 2007. Westinghouse blades are also planned to be loaded in the next Unit 1 cycle beginning in March of 2008.

There have been no other changes to the control rods, control rod drive system, or scram time testing practices that would invalidate the results or conclusions of this data.

6.0 Commitments As discussed in the CLIP model SE published in the Federal Register for this TS improvement, Plant Hatch is making the following Regulatory Commitment with the understanding that the NRC will make it as a condition for the issuance of this requested amendment:

Plant Hatch will incorporate the revised acceptance criteria value of 7.5 percent into the TS Bases for Plant Hatch Units 1 and 2 in accordance with the Bases Control Program described in TS section 5.5.14.

7.0 No Significant Hazards Consideration Plant Hatch has reviewed the proposed no significant hazards consideration determination published on August 23,2004 (69 FR 51854) as part of the CLIIP. Plant Hatch has concluded that the proposed determination presented in the notice is applicable to Plant Hatch and the determination is hereby incorporated by reference to satisfy the requirements of 10 CFR 50.9 1(a).

8.0 Environmental Evaluation Plant Hatch has reviewed the environmental evaluation included in the model SE as part of the CLIIP. Plant Hatch has concluded that the staffs findings presented in that evaluation are applicable to Plant Hatch and the evaluation is hereby incorporated by reference for this application.

Enclosure 1 Edwin I. Hatch Nuclear Plant, Units 1 and 2 Technical Specifications Amendment request to Revise Control Rod Scram Time Testing Surveillance Frequency Description and Verification of Applicability 9.0 Precedent This application is being made in accordance with the CLIIP. Plant Hatch is not proposing variations or deviations from the TS changes described in TSTF-460 or the NRC staffs model SE published on August 23,2004 (69 FR 51854).

10.0 References Federal Register Notice: Notice of Availability of Model Application Concerning Technical Specifications Improvement Regarding Revision to the Control Rod Scram Time Testing frequency in STS 3.1.4, "Control Rod Scram Times" for General Electric Boiling Water Reactors Using the Consolidated Line Item Improvement Process, published August 23,2004 (60 FR 5 1854).

Enclosure 2 Edwin I. Hatch Nuclear Plant, Units 1 and 2 Technical Specifications Amendment request to Revise Control Rod Scram Time Testing Surveillance Frequency Marked-Up Technical Specifications and Bases Pages

Control Rod Scram Times 3.1.4 SURVEILLANCE REQUlREMENTS

......................................................... NOTE..................................................... -------

During single control rod scram time Surveillances, the control rod drive (CRD) pumps shall be isolated from the associated scram accumulator.

SR 3.1.4.1 pressure 2 800 psig. movement within the reactor pressure Prior to exceeding 40% RTP after each reactor shutdown SR 3.1.4.2 Verify, for a representative sample, each tested control rod scram time is within the limits of SR 3.1.4.3 Verify each affected control rod scram time is Prior to declaring steam dome pressure. OPERABLE after work on control rod SR 3.1.4.4 Verrfy each affected control rod scram time is Prior to exceeding within the limits of Table 3.1.4-1 with reactor 40% RTP after steam dome pressure 2 800 psig. work on control rod HATCH UNIT 1 Amendment No.

Control Rod Scram Times 3.1.4 SURVEILLANCE REQUIREMENTS

.......................................................... NOTE------------------------------------------------------------

During single control rod scram time Surveillances, the control rod drive (CRD) pumps shall be isolated from the associated scram accumulator.

SR 3.1.4.1 Verify each control rod scram time is within the Prior to exceeding limits of Table 3.1.4-1 with reactor steam dome 40% RTP after fuel pressure 2 800 psig. movement within the reactor pressure Prior to exceeding 40% RTP after each reactor shutdown SR 3.1.4.2 Verify, for a representative sample, each tested control rod scram time is within the limits of SR 3.1.4.3 Verify each affected control rod scram time is steam dome pressure. OPERABLE after work on control rod SR 3.1.4.4 Verify each affected control rod scram time is Prior to exceeding within the limits of Table 3.1.4-1 with reactor 40% RTP after steam dome pressure r 800 psig. work on control rod HATCH UNIT 2 Amendment No.

Control Rod Scram Times B 3.1.4 BASES SURVEILLANCE SR 3.1.4.1 (continued)

REQUIREMENTS acceptable scram times for the transients analyzed in References 3 and 4.

Maximum scram insertion times occur at a reactor steam dome pressure of approximately 800 psig because of the competing effects of reactor steam dome pressure and stored accumulator energy.

Therefore, demonstration of adequate scram times at reactor steam dome pressure 2 800 psig ensures that the measured scram times will be within the specified limits at higher pressures. Limits are specified as a function of reactor pressure to account for the sensitivity of the scram insertion times with pressure and to allow a range of pressures over which scram time testing can be performed. To ensure that scram time testing is performed within a reasonable time following fuel movement within the reactor pressure vessel or after a shutdown 2 120 days or longer, control rods are required to be tested before exceeding 40% RTP. In the event fuel movement is limited to selected core cells, it is the intent of this SR that only those CRDs associated with the core cells, affected by the fuel movements are required to be scram time tested. This Frequency is acceptable considering the additional surveillances performed for control rod OPERABILITY, the frequent verification of adequate accumulator pressure, and the required testing of control rods affected by work on control rods or the CRD System.

ssible to avoid based on operating experience that has shown control rod scram times do not significantly change over an operating cycle. This Frequency is also reasonable based on the additional Surveillances (continued)

HATCH UNIT 1 B 3.1 -22 Em!BE?a

Control Rod Scram Times B 3.1.4 BASES SURVElLLANCE SR 3.1.4.1 (continued)

REQUIREMENTS acceptable scram times for the transients analyzed in References 3 and 4. .

Maximum scram insertion times occur at a reactor steam dome pressure of approximately 800 psig because of the competing effects of reactor steam dome pressure and stored accumulator energy.

Therefore, demonstration of adequate scram times at reactor steam dome pressure 2 800 psig ensures that the measured scram times will be within the specified limits at higher pressures. Limits are specified as a function of reactor pressure to account for the sensitivity of the scram insertion times with pressure and to allow a range of pressures over which scram time testing can be performed. To ensure that scram time testing is performed within a reasonable time following fuel movement within the reactor pressure vessel or after a shutdown 2 120 days or longer, control rods are required to be tested before exceeding 40% RTP. In the event fuel movement is limited to selected core cells, it is the intent of this SR that only those CRDs associated with the core cells affected by the fuel movements are required to be scram time tested. This Frequency is acceptable considering the additional surveillances performed for control rod OPERABILITY, the frequent verification of adequate accumulator pressure, and the required testing of control rods affected by work on control rods or the CRD System.

Additional testing of a sample of control rods is required to verify the continued performance of the scram function during the cycle. A unnecessary testing at power, even if the cont have been previously tested in a sample. The based on operating experience that has shown control rod scram times do not significantly change over an operating cycle. This Frequency is also reasonable based on the additional Surveillances (continued)

HATCH UNIT 2 B 3.1-22

Enclosure 3 Edwin I. Hatch Nuclear Plant, Units 1 and 2 Technical Specifications Amendment request to Revise Control Rod Scram Time Testing Surveillance Frequency Clean Typed Technical Specifications and Bases Pages

Control Rod Scram Times 3.1.4 SURVEILLANCE REQUIREMENTS

........................................................... NOTE............................................................

During single control rod scram time Surveillances, the control rod drive (CRD) pumps shall be isolated from the associated scram accumulator.

SURVEILLANCE I FREQUENCY SR 3.1.4.1 Verify each control rod scram time is within the Prior to exceeding limits of Table 3.1.4-1 with reactor steam dome 40% RTP after fuel pressure 1 800 psig. movement within the reactor pressure vessel Prior to exceeding 40% RTP after each reactor shutdown r 120 days SR 3.1.4.2 Verify, for a representative sample, each tested 200 days I control rod scram time is within the limits of cumulative Table 3.1.4-1 with reactor steam dome pressure operation in 2 800 psig. MODE 1 SR 3.1.4.3 Verify each affected control rod scram time is Prior to declaring within the limits of Table 3.1.4-1 with any reactor control rod steam dome pressure. OPERABLE after work on control rod or CRD System that could affect scram time SR 3.1.4.4 Verify each affected control rod scram time is Prior to exceeding within the limits of Table 3.1.4-1 with reactor 40% RTP after steam dome pressure 2 800 psig. work on control rod or CRD System that could affect scram time HATCH UNIT 1 Amendment No.

Control Rod Scram Times 3.1.4 SURVEILLANCE REQUIREMENTS

........................................................... NOTE............................................................

During single control rod scram time Surveillances, the control rod drive (CRD) pumps shall be isolated from the associated scram accumulator.

SURVEILLANCE I FREQUENCY SR 3.1.4.1 Verify each control rod scram time is within the Prior to exceeding limits of Table 3.1.4-1 with reactor steam dome 40% RTP after fuel pressure 2 800 psig. movement within the reactor pressure vessel Prior to exceeding 40% RTP after each reactor shutdown 2 120 days SR 3.1.4.2 Verify, for a representative sample, each tested 200 days I control rod scram time is within the limits of cumulative Table 3.1.4-1 with reactor steam dome pressure operation in 2 800 psig. MODE 1 SR 3.1.4.3 Verify each affected control rod scram time is Prior to declaring within the limits of Table 3.1.4-1 with any reactor control rod steam dome pressure. OPERABLE after work on control rod or CRD System that could affect scram time SR 3.1.4.4 Verify each affected control rod scram time is Prior to exceeding within the limits of Table 3.1.4-1 with reactor 40% RTP after steam dome pressure 2 800 psig. work on control rod or CRD System that could affect scram time HATCH UNIT 2 3.1-10 Amendment No.

Control Rod Scram Times B 3.1.4 BASES SURVEILLANCE SR 3.1.4.1 (continued)

REQUIREMENTS acceptable scram times for the transients analyzed in References 3 and 4.

Maximum scram insertion times occur at a reactor steam dome pressure of approximately 800 psig because of the competing effects of reactor steam dome pressure and stored accumulator energy.

Therefore, demonstration of adequate scram times at reactor steam dome pressure 2 800 psig ensures that the measured scram times will be within the specified limits at higher pressures. Limits are specified as a function of reactor pressure to account for the sensitivity of the scram insertion times with pressure and to allow a range of pressures over which scram time testing can be performed. To ensure that scram time testing is performed within a reasonable time following fuel movement within the reactor pressure vessel or after a shutdown 2 120 days or longer, control rods are required to be tested before exceeding 40% RTP. In the event fuel movement is limited to selected core cells, it is the intent of this SR that only those CRDs associated with the core cells affected by the fuel movements are required to be scram time tested. This Frequency is acceptable considering the additional surveillances performed for control rod OPERABILITY, the frequent verification of adequate accumulator pressure, and the required testing of control rods affected by work on control rods or the CRD System.

Additional testing of a sample of control rods is required to verify the continued performance of the scram function during the cycle. A representative sample contains at least 10% of the control rods. The sample remains representative if no more than 7.5% of the control 1 rods in the sample tested are determined to be "slow". With more than 7.5% of the sample declared to be "slowuper the criteria in Table 3.1.4-1, additional control rods are tested until this 7.5%

criterion (i.e., 7.5% of the entire sample size) is satisfied, or until the total number of "slow" control rods (throughout the core, from all Surveillances) exceeds the LC0 limit. For planned testing, the control rods selected for the sample should be different for each test. Data from inadvertent scrams should be used whenever possible to avoid unnecessary testing at power, even if the control rods with data may have been previously tested in a sample. The 200 day Frequency is I based on operating experience that has shown control rod scram times do not significantly change over an operating cycle. This Frequency is also reasonable based on the additional Surveillances (continued)

HATCH UNIT 1 B 3.1-22

Control Rod Scram Times B 3.1.4 BASES SURVEILLANCE SR 3.1.4.1 (continued)

REQUIREMENTS acceptable scram times for the transients analyzed in References 3 and 4.

Maximum scram insertion times occur at a reactor steam dome pressure of approximately 800 psig because of the competing effects of reactor steam dome pressure and stored accumulator energy.

Therefore, demonstration of adequate scram times at reactor steam dome pressure 2 800 psig ensures that the measured scram times will be within the specified limits at higher pressures. Limits are specified as a function of reactor pressure to account for the sensitivity of the scram insertion times with pressure and to allow a range of pressures over which scram time testing can be performed. To ensure that scram time testing is performed within a reasonable time following fuel movement within the reactor pressure vessel or after a shutdown r 120 days or longer, control rods are required to be tested before exceeding 40% RTP. In the event fuel movement is limited to selected core cells, it is the intent of this SR that only those CRDs associated with the core cells affected by the fuel movements are required to be scram time tested. This Frequency is acceptable considering the additional surveillances performed for control rod OPERABILITY, the frequent verification of adequate accumulator pressure, and the required testing of control rods affected by work on control rods or the CRD System.

Additional testing of a sample of control rods is required to verify the continued performance of the scram function during the cycle. A representative sample contains at least 10% of the control rods. The sample remains representative if no more than 7.5% of the control 1 rods in the sample tested are determined to be "slow". With more than 7.5% of the sample declared to be "slow" per the criteria in Table 3.1.4-1, additional control rods are tested until this 7.5%

criterion (i.e., 7.5% of the entire sample size) is satisfied, or until the total number of "slow" control rods (throughout the core, from all Surveillances) exceeds the LC0 limit. For planned testing, the control rods selected for the sample should be different for each test. Data from inadvertent scrams should be used whenever possible to avoid unnecessary testing at power, even if the control rods with data may have been previously tested in a sample. The 200 day Frequency is I based on operating experience that has shown control rod scram times do not significantly change over an operating cycle. This Frequency is also reasonable based on the additional Surveillances (continued)

HATCH UNIT 2 6 3.1 -22

Enclosure 4 Edwin I. Hatch Nuclear Plant, Units 1 and 2 Technical Specifications Amendment request to Revise Control Rod Scram Time Testing Surveillance Frequency List of Regulatory Commitments

List of Regulatory Commitments The following table identifies the action committed by Southern Nuclear Operating Company in this document for Edwin I. Hatch Nuclear Plant. Any other statements in this submittal are provided for information purposes and are not considered to be a regulatory commitment.

Type Scheduled One-Time Continuing Completion Date Commitment Action Compliance (If Required)

Plant Hatch will incorporate the revised slow control rod acceptance criteria of 7.5 percent into the TS Bases. Upon This change will be x implementation of incorporated in accordance the TS change.

with the Bases Control Program described in TS section 5.5.14.