NL-21-0634, Request to Eliminate Automatic Main Steam Line Isolation on High Turbine Building Area Temperature

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Request to Eliminate Automatic Main Steam Line Isolation on High Turbine Building Area Temperature
ML21286A595
Person / Time
Site: Hatch  Southern Nuclear icon.png
Issue date: 10/13/2021
From: Gayheart C
Southern Nuclear Operating Co
To:
Document Control Desk, Office of Nuclear Reactor Regulation
References
NL-21-0634
Download: ML21286A595 (38)
v • d • e


Text

3535 Colonnade Parkway Cheryl A. Gayheart Birmingham, AL 35243 Regulatory Affairs Director 205 992 5316 tel 205 992 7601 fax cagayhea@southernco.com October 13, 2021 Docket Nos.: 50-321 NL-21-0634 50-366 ATTN: Document Control Desk U. S. Nuclear Regulatory Commission Washington, D. C. 20555-0001 Edwin I. Hatch Nuclear Plant - Units 1 and 2 Request to Eliminate Automatic Main Steam Line Isolation on High Turbine Building Area Temperature Ladies and Gentlemen:

Pursuant to 10 CFR 50.90, Southern Nuclear Operating Company (SNC) is submitting a request for an amendment to the Technical Specifications (TS) for Edwin I. Hatch Nuclear Plant (HNP),

Units 1 and 2.

The proposed change would revise technical specification (TS) 3.3.6.1, Primary Containment Isolation Instrumentation, Table 3.3.6.1-1, to eliminate the requirement for automatic main steam line isolation on high turbine building area temperature (Function 1.f). In lieu of automatic isolation, a new specification, TS 3.7.10, "Turbine Building (TB) Maximum Area Temperature, is proposed that requires monitoring the turbine building maximum area temperature and a plant shut down if excessive main steam line leakage is detected.

The enclosure provides a description and assessment of the proposed changes. Attachment 1 provides the existing TS pages marked to show the proposed changes. Attachment 2 provides revised (clean) TS pages. Attachment 3 provides the existing TS Bases pages marked to show revisions associated with the proposed TS changes and the Bases for the new TS 3.7.10. The Bases changes are provided for information only.

SNC requests approval of the proposed license amendments within one year of the NRC acceptance of this request. The proposed changes would be implemented within 90 days of issuance of the amendments.

In accordance with 10 CFR 50.91, a copy of this application, with attachments, is being provided to the designated Georgia Official.

This letter contains no NRC commitments. If you have any questions, please contact Ryan Joyce at 205-992-6468.

U.S. Nuclear Regulatory Commission NL-21-0634 Page 2 I declare under penalty of perjury that the foregoing is true and correct. Executed on the 13th day of October 2021.

Respectfully submitted, C. A. Gayheart Director, Regulatory Affairs Southern Nuclear Operating Company CAG/tle

Enclosure:

Evaluation of Proposed Change cc: Regional Administrator, Region ll NRR Project Manager - Hatch Senior Resident Inspector - Hatch Director, Environmental Protection Division - State of Georgia RType: CHA02.004

Edwin I. Hatch Nuclear Plant - Units 1 and 2 Request to Eliminate Automatic Main Steam Line Isolation on High Turbine Building Area Temperature Enclosure Evaluation of Proposed Change

Enclosure to NL-21-0634 Evaluation of Proposed Change ENCLOSURE Evaluation of Proposed Change

Subject:

Request to Eliminate Automatic Main Steam Line Isolation on High Turbine Building Area Temperature

1.

SUMMARY

DESCRIPTION

2. DETAILED DESCRIPTION 2.1 System Design and Operation 2.2 Current Technical Specification Requirements 2.3 Reason for Proposed Change 2.4 Description of Proposed Change
3. TECHNICAL EVALUATION
4. REGULATORY EVALUATION 4.1 Applicable Regulatory Requirements/Criteria 4.2 Precedent 4.3 No Significant Hazards Consideration Determination Analysis 4.4 Conclusions
5. ENVIRONMENTAL CONSIDERATION
6. REFERENCES ATTACHMENTS:
1. HNP Unit 1 and Unit 2 Technical Specifications Marked-up Pages
2. HNP Unit 1 and Unit 2 Technical Specifications Revised TS Pages
3. HNP Unit 1 and Unit 2 Technical Specifications Bases Marked-up Pages (Information Only)

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Enclosure to NL-21-0634 Evaluation of Proposed Change

1.

SUMMARY

DESCRIPTION The proposed change would revise the Edwin I. Hatch Nuclear Plant (HNP), Units 1 and 2, Technical Specification (TS) 3.3.6.1, Primary Containment Isolation Instrumentation, Table 3.3.6.1-1, to eliminate the requirement for automatic main steam line isolation on high turbine building area temperature (Function 1.f). In lieu of automatic isolation, a new specification, TS 3.7.10, "Turbine Building (TB) Maximum Area Temperature, is proposed that requires monitoring the turbine building maximum area temperature and a plant shut down if excessive main steam line leakage is detected.

2. DETAILED DESCRIPTION 2.1 System Design and Operation Main Steam Line (MSL) leakage in the TB is limited to protect the initial conditions assumed in the accident analyses. Analyses are performed for large MSL breaks, such as the Main Steam Line Break (MSLB) accident (see HNP Unit 2 Final Safety Analysis Report (FSAR)

Section 15.3.4), but MSL leakage in the TB is not considered in other design basis accident (DBA) or transient analyses. As a result, small MSL leaks in the TB could result in post-accident doses that may exceed the analyzed values. Direct monitoring of small amounts of MSL leakage is not practical, so monitoring the maximum area temperatures near the MSLs is used as a surrogate indication of MSL leakage.

The Turbine Building Area Temperature - High Function closes the Main Steam Isolation Valves (MSIVs). The function monitors area temperature near the MSLs in the condenser bay area of the TB. The Turbine Building Area Temperature - High Function receives input from 64 channels. Each channel has one temperature element. Four channels from each MSL provide input to one of the four trip strings. Two trip strings make up each trip system and both trip systems must trip to cause an MSL isolation. Each trip string has 16 inputs (4 per MSL), any one of which will trip the trip string. The trip strings are arranged in a one-out-of-two taken twice logic.

While 64 channels of Turbine Building Area Temperature - High Function are available, only 32 channels are required to be operable to ensure that no single instrument failure can preclude the isolation function. The 32-channel requirement is further divided, as noted in footnote (b) to TS Table 3.3.6.1-1, into 16 channels per trip system with 8 channels per trip string. Each trip string is required to have 2 channels per MSL, with no more than 40 feet separating any two operable channels.

Actuation of both TB Area Temperature - High trip systems could be caused by temperature indications on different MSLs and different areas of the TB, which would not be an indication of MSL leakage.

The Allowable Value of 200ºF is chosen to detect a leak equivalent to 1% to 10% of rated steam flow.

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Enclosure to NL-21-0634 Evaluation of Proposed Change 2.2 Current Technical Specification Requirements Limiting Condition for Operation (LCO) 3.3.6.1 requires the primary containment isolation instrumentation for each Function in Table 3.3.6.1-1 to be operable. Table 3.3.6.1-1, Function 1.f, "Turbine Building Area Temperature - High," requires 16 channels per trip system to be operable in Modes 1, 2, and 3. Function 1.f is modified by Footnote (b) which states that there must be 8 channels per operable trip string, and that each operable trip string must have 2 channels per MSL, with no more than 40 ft separating any two operable channels. The allowable value for this Function is 200 °F.

LCO 3.3.6.1, Action D requires isolation of the MSL in 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />, or to be in Mode 3 in 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and Mode 4 in 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />, if:

  • One or more automatic functions with isolation capability is not maintained.

2.3 Reason for Proposed Change The ambient temperature of the monitored TB area can trend close to the isolation setpoint.

This narrow operating margin has caused one of the trip channels to actuate (i.e., a half isolation) for reasons other than actual steam leaks in the area. This has occurred because of hot weather, reduced efficiency of the turbine building area chillers, or instrument drift. If both TB Area Temperature - High trip systems were to initiate an isolation signal, a full Group 1 isolation and reactor trip would result. Group 1 isolation closes the MSIVs, making the main feedwater system unavailable for scram recovery. HNP would rely on the alternate methods (e.g., high pressure coolant injection (HPCI), reactor core isolation cooling (RCIC),

suppression pool cooling) for core cooling and reactor water level control. Such a shutdown would be considered a complicated scram. It is HNP's practice to shut down the plant to make repairs (e.g., recalibrate instrumentation or service turbine building area chillers) rather than risk a complicated scram due to the sudden closure of the MSIVs.

Replacing this automatic MSIV isolation requirement with a monitoring requirement and a manual shutdown if MSL leakage is detected will eliminate the risk of an unnecessary plant transient while still providing the appropriate remedial actions to ensure the plant is operating safely and within the assumed plant conditions.

2.4 Description of Proposed Change The proposed change deletes Function 1.f, "Turbine Building Area Temperature - High,"

and the associated footnote (b) from TS Table 3.3.6.1-1 of the Unit 1 and Unit 2 TS.

Deletion of Function 1.f does not require modification to any Actions or Surveillance Requirements in TS 3.3.6.1. Current footnote (c) in TS Table 3.3.6.1-1 and its reference are relabeled as footnote (b). LCO 3.3.6.1, Action D which requires isolation of the MSL in 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />, or to be in Mode 3 in 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and Mode 4 in 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />, is retained as it is referenced by other Functions.

The proposed change adds a new Specification 3.7.10, "Turbine Building (TB) Maximum Area Temperature." The new LCO 3.7.10 requires the turbine building maximum area temperature to be 200°F. The specification is applicable in Modes, 1, 2, and 3, the same E-3

Enclosure to NL-21-0634 Evaluation of Proposed Change as existing Function 1.f. SR 3.7.10.1 requires verification that the turbine building maximum temperature is 200°F on a frequency controlled by the Surveillance Frequency Control Program (SFCP). The initial frequency will be 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

If the turbine building maximum temperature exceeds 200°F, the Actions require immediate action to verify that no MSL leak exists, and periodic verification every 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> thereafter.

If it cannot be verified that there is not an MSL leak or if the periodic verification is not performed, a plant shutdown is required. The plant must enter Mode 3 within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and Mode 4 must be entered within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />.

Associated changes would be made to the Unit 1 and Unit 2 TS Bases. The Bases for SR 3.7.10.1 state that the turbine building air temperature is monitored for each of the MSLs, with no more than 40 feet separating any two temperature monitoring elements. The proposed TS 3.7.10 and associated TS Bases are shown in Attachments 1 and 3, respectively.

Following approval of the proposed TS change, a plant modification to remove the automatic MSIV closure function on high turbine building temperature will be evaluated by SNC under the provisions of 10 CFR 50.59.

3. TECHNICAL EVALUATION The proposed change replaces an automatic MSL isolation on high turbine building temperature with a monitoring and evaluation requirement, and a manual reactor shutdown if MSL leakage exists.

There are two purposes for the MSL turbine building high temperature MSIV isolation function:

1. Leak Before Break - The basis of this criterion is to isolate in order to prevent the leak from becoming a break. There was historical evidence that leaks would grow and become a break if not isolated. Early intergranular stress corrosion crack (IGSCC) propagation studies on stainless steel reactor coolant pressure boundary (RCPB) pipes in the containment showed that isolating a small leak provided assurance that the leak would not grow to a break. This same basis was conservatively applied to main steam carbon steel piping in the turbine building. However, later studies determined that cracks in main-steam piping are not subject to IGSCC due to the lack of a corrosive environment. As a conservative action, the proposed TS 3.7.10 would require a plant shutdown if a leak is detected.
2. Dose Limits - The Loss of Coolant Accident (LOCA) analysis does not assume any release of post-accident radioactive material into the turbine building from small MSL leaks. If a small MSL leak was present and a LOCA occurred, the analyzed dose limits could be exceeded. A LOCA is not caused by a small MSL leak in the TB, and it is unnecessary to assume they occur simultaneously. The proposed TS 3.7.10 provides assurance that an MSL leak would be promptly identified and requires an immediate shutdown should a leak exist, eliminating a small MSL leak as a preexisting condition in the LOCA analysis.

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Enclosure to NL-21-0634 Evaluation of Proposed Change Neither of these purposes require an automatic isolation of the MSLs on turbine building high temperature or are dependent on an immediate reactor scram to assure plant safety. Given the purposes of the function, the consequences of an automatic reactor scram due to closure of the MSIVs is unwarranted.

As an alternative, the proposed TS 3.7.10 will ensure that an MSL steam leak in the turbine building will be promptly detected and corrected.

The proposed LCO 3.7.10 requires that the TB maximum area temperature be 200°F. The limit of 200°F is based on detecting a leak equivalent to 1% to 10% of rated steam flow and is the allowable value of the current Function 1.f. HNP simulator modeling has demonstrated that a small (1%) MSL leak would be rapidly identified by plant operators in the control room.

The Applicability of LCO 3.7.10 is Modes 1, 2, and 3. In Modes 1, 2, and 3, a DBA could result in the release of radioactive material into the TB if there is a leak in the MSLs. In Modes 4 and 5, the probability and consequences of a DBA with fission product release into the TB are reduced because of the pressure and temperature limitations in these modes. Therefore, maintaining TB area temperature within limits is not required in Mode 4 or 5. The proposed Applicability is the same as the current Function 1.f.

Proposed Surveillance Requirement (SR) 3.7.10.1 requires verification that the TS area temperature is 200°F. The Frequency is controlled under the SFCP, and the initial frequency is every 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. As stated in SR 3.0.1, SRs must be met between performances of the Surveillance. If the TB maximum area temperature exceeds 200°F, indications in the main control room will alert operators to take actions.

The Bases of SR 3.7.10.1 state that verification that TB maximum area temperature requires measuring temperature for each MSL and that the monitoring locations must not be separated by more than 40 feet. This reflects the existing Footnote (b) to Function 1.f that states that an operable trip string must have 2 channels per MSL with no more than 40 ft separating any two operable channels. The footnote is based on maintaining automatic trip capability on a potential leak from any MSL and at any location. The Bases retain the Footnote (b) concerns in a manner consistent with a monitoring requirement instead of an automatic trip function. Placing this information in the SR Bases is consistent with similar requirements in the HNP Unit 1 and 2 TS. For example, SR 3.6.1.5.1 requires verification that the drywell average temperature is within limit. The associated Bases state, "Drywell air temperature is monitored in all quadrants and at various elevations."

The TS 3.7.10 Actions apply if TB maximum area temperature is exceeded. Required Action A.1 requires immediate action to determine if there is an MSL leak. TS Section 1.3 defines a Completion Time of "Immediately," as, "the Required Action should be pursued without delay and in a controlled manner."

Indications of a small MSL leak in the turbine building include, but are not limited to:

  • An unexpected, sudden rise in area temperature,
  • An unexpected increase in radiation monitor readings,
  • An unexpected rise in turbine building sump levels,
  • An unexpected decrease in plant electrical output, and
  • Visual and sound indications.

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Enclosure to NL-21-0634 Evaluation of Proposed Change TB area temperature may be elevated due to reasons other than an MSL leak, such as hot weather, reduced turbine building area chiller capacity, and faulty temperature detectors.

Verification will determine whether the elevated temperature is due to an MSL leak or another reason.

If the elevated temperature is determined to not be due to an MSL leak, as long as the TB maximum area temperature exceeds 200°F Required Action A.2 requires periodic verification that no MSL leak exists every 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. The area monitored in the TB has elevated radiation levels and adverse environmental conditions. The 12-hour Completion Time balances the small likelihood of a MSL leak occurring since the last verification against the risks of exposing workers to the radiological and environmental conditions in order to perform the verification.

If an MSL leak is detected or if the periodic verification is not performed, Action B requires a plant shutdown. The plant must be brought to at least Mode 3 within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and to Mode 4 within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />. The proposed Completion Times are reasonable, based on operating experience, to reach the required plant conditions from full power conditions in an orderly manner and without challenging plant systems.

Environmental qualifications are not applied to equipment in the turbine building, so removing the automatic isolation function and adding a manual shutdown requirement on high TB maximum area temperature will have no effect on equipment qualification.

Although this license amendment request is not risk-informed, SNC has developed risk insights related to the proposed change. The risk analysis was performed to demonstrate with reasonable assurance that eliminating the requirement for automatic MSL isolation on high turbine building area temperature is within the current risk acceptance guidelines in Regulatory Guide 1.174. The risk analysis was based on the ¨CDF and ¨LERF that results from assuming the turbine building steam line break high temperature function fails. This analysis does not assume operator action to detect a steam leak and assumes that unisolated breaks of any size result in core damage and large early release. In addition, this analysis does not credit the reduced change of spurious MSIV actuation from a fire. This analysis supports the acceptability of the proposed change.

4. REGULATORY EVALUATION 4.1 Applicable Regulatory Requirements/Criteria The proposed change has been evaluated to determine whether applicable regulations and requirements continue to be met. SNC has determined that the proposed change does not require any exemptions or relief from regulatory requirements. The following applicable regulations and regulatory requirements were reviewed in making this determination:
  • The NRC's regulatory requirements related to the content of TS are set forth in 10 CFR 50.36. The NRC has provided guidance for the contents of TS in its "Final Policy Statement on Technical Specifications Improvements for Nuclear Power Reactors" (Final Policy Statement), 58 FR 39132, July 22, 1993. The Final Policy Statement identified four criteria to be used in determining whether particular safety functions are required to be included in the TS. The criteria set forth in the Final Policy Statement have been E-6

Enclosure to NL-21-0634 Evaluation of Proposed Change codified and incorporated into 10 CFR 50.36 (60 FR 36953, July 19, 1995). The criteria are (1) installed instrumentation that is used to detect, and indicate in the control room, a significant abnormal degradation of the reactor coolant pressure boundary; (2) a process variable, design feature, or operating restriction that is an initial condition of a design basis accident or transient analysis that either assumes the failure of or presents a challenge to the integrity of a fission product barrier; (3) a structure, system, or component that is part of the primary success path and which functions or actuates to mitigate a design basis accident or transient that either assumes the failure of or presents a challenge to the integrity of a fission product barrier; and (4) a structure, system, or component which operating experience or probabilistic risk assessment (PRA) has shown to be significant to public health and safety. As a result, TS requirements which satisfy any of the criteria in 10 CFR 50.36 must be retained in the TS.

MSL leakage in the turbine building is monitored to protect the assumptions of the accident dose analysis. Therefore, the requirement to monitor turbine building maximum area temperature is treated as an operating restriction that is an initial condition of a design basis accident or transient analysis that either assumes the failure of, or presents a challenge to, the integrity of a fission product barrier and is maintained in the TS per Criterion 2. Revising the requirement from an automatic isolation to manual detection and shutdown does not affect the ability to satisfy Criterion 2.

Piping systems penetrating primary reactor containment shall be provided with leak detection, isolation, and containment having redundancy, reliability, and performance capabilities which reflect the importance to safety of isolating these piping systems.

The HNP design incorporates various and diverse leak detection and containment isolation features to meet the requirements of GDC 54. It is proposed that the Turbine Building Area Temperature - High isolation function be removed from the TS for containment isolation instrumentation. Appropriate automatic isolations for MSIVs are still retained in accordance with GDC 54 by other diverse leakage detection features such as detection of low reactor water level, high main steam line flow, low main steam line pressure, and main steam tunnel high ambient temperature.

4.2 No Significant Hazards Consideration Determination Analysis Southern Nuclear Operating Company (SNC) has proposed a change to the Edwin I. Hatch Nuclear Plant (HNP), Units 1 and 2, Technical Specifications (TS). TS 3.3.6.1, Primary Containment Isolation Instrumentation, Table 3.3.6.1-1, is revised to eliminate automatic main steam line isolation on high turbine building area temperature (Function 1.f). In lieu of automatic isolation, a new specification, TS 3.7.10, "Turbine Building (TB) Maximum Area Temperature, is proposed that requires monitoring the turbine building maximum area temperature and a plant shut down if main steam line leakage is detected.

SNC has evaluated whether or not a significant hazards consideration is involved with the proposed amendment(s) by focusing on the three standards set forth in 10 CFR 50.92, Issuance of amendment, as discussed below:

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Enclosure to NL-21-0634 Evaluation of Proposed Change

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

Response: No.

The proposed change eliminates the automatic MSIV isolation function associated with Turbine Building (TB) High Temperature from the requirements of the Technical Specifications (TS) and creates TS requirements for TB maximum area temperature monitoring in a new TS 3.7.10. The proposed change therefore deletes Function 1.f and Footnote (b) from TS Table 3.3.6.1-1, which administratively results in Footnote (c) being relabeled as Footnote (b). The new TS 3.7.10 requires periodic monitoring of TB area temperature and a plant shutdown if Main Steam Line (MSL) Leakage is detected.

Automatic isolation of the MSIVs on TB high area temperature is not an initiator of any accident previously evaluated. A manual plant shutdown initiated because MSL leakage in the TB is not an initiator of any accident previously evaluated.

There is no credit taken in any licensing basis analysis for the main steam line (MSL) main steam isolation valve (MSIV) closure on MSL Turbine Building High Temperature, and there are no calculations that credit the subject isolation function as a mitigative feature. A review of Chapters 6 and 15 of the Unit 2 Updated Final Safety Analysis Report (UFSAR), which are common to both units, confirmed that the MSL isolation function on MSL Turbine Building High Temperature was not credited in any analysis for mitigating: fuel cladding damage, challenges to vessel integrity, or dose to plant staff or the general public. This conclusion is consistent with the discussion of the function in the current TS Bases Section B 3.3.6.1. Therefore, requiring a manual plant shutdown in lieu of an automatic isolation of the MSIVs (resulting in an automatic plant trip) has no effect on the consequences of any accident previously evaluated.

Therefore, the proposed change does not involve a significant increase in the probability or consequences of an accident previously evaluated.

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

Response: No.

The proposed change eliminates the automatic MSIV isolation function associated with TB High Temperature from the requirements of the TS and creates TS requirements for TB maximum area temperature monitoring in a new TS 3.7.10. The proposed change therefore deletes Function 1.f and Footnote (b) from TS Table 3.3.6.1-1, which administratively results in Footnote (c) being relabeled as Footnote (b). The new TS 3.7.10 requires periodic monitoring of TB area temperature and a plant shutdown if MSL Leakage is detected.

The proposed change alters the design function of the TB maximum area temperature monitoring from an automatic actuation of the MSIVs to a manual determination and, if an MSL leak is found, a plant shutdown. Eliminating the automatic isolation of the MSIVs (and associated reactor trip) will not create a new or different kind of accident E-8

Enclosure to NL-21-0634 Evaluation of Proposed Change from those previously evaluated as a Main Steam Line Break has been evaluated.

Elimination of the automatic isolation function will not create a new failure mechanism as a plant shutdown continues to be required if an MSL leak is detected. The proposed change from an automatic shutdown to a manual shutdown will not create any credible new failure mechanisms, malfunctions, or accident initiators not considered in the design and licensing bases. The unlikely failure to manually detect an MSL leak and shutdown the plant and that failure leading to a Main Steam Line Break has already been evaluated and is not a new type of accident.

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

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

Response: No.

The proposed change eliminates the automatic MSIV isolation function associated with TB High Temperature from the requirements of the TS and creates TS requirements for TB maximum area temperature monitoring in a new TS 3.7.10. The proposed change therefore deletes Function 1.f and Footnote (b) from TS Table 3.3.6.1-1, which administratively results in Footnote (c) being relabeled as Footnote (b). The new TS 3.7.10 requires periodic monitoring of TB area temperature and a plant shutdown if MSL Leakage is detected.

The proposed change does not affect any Safety Limits or controlling numerical values for a parameter established in the updated final safety analysis report or any specific values that define margin that are established in the plants licensing basis. The MSIV isolation function on TB high temperature is not credited as a mitigating feature in any analysis which establishes thermal limits, evaluates peak vessel pressure, evaluates peak containment or drywell pressure, or evaluates onsite and offsite radiological consequences. As a result, changing the requirement from an automatic reactor trip to a manual plant shutdown if an MSL leak were to be detected will not have any significant effect on any safety margins established in the license basis.

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

Based on the above SNC concludes that the proposed amendment presents no significant hazards consideration under the standards set forth in 10 CFR 50.92(c), and, accordingly, a finding of "no significant hazards consideration" is justified.

4.4 Conclusions In conclusion, based on the considerations discussed above, (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the Commissions regulations, and (3) the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public.

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Enclosure to NL-21-0634 Evaluation of Proposed Change

5. ENVIRONMENTAL CONSIDERATION SNC has determined that the proposed amendment would change a requirement with respect to installation or use of a facility component located within the restricted area, as defined in 10 CFR 20, or would change an inspection or surveillance requirement. However, the proposed amendment does not involve (i) a significant hazards consideration, (ii) a significant change in the types or a significant increase in the amounts of any effluents that may be released offsite, or (iii) a significant increase in individual or cumulative occupational radiation exposure.

Accordingly, the proposed amendment meets the eligibility criterion for categorical exclusion set forth in 10 CFR 51.22(c)(9). Therefore, pursuant to 10 CFR 51.22(b), no environmental impact statement or environmental assessment need be prepared in connection with the proposed amendment.

6. REFERENCES None.

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Edwin I. Hatch Nuclear Plant - Units 1 and 2 Request to Eliminate Automatic Main Steam Line Isolation on High Turbine Building Area Temperature Attachment 1 HNP Unit 1 and Unit 2 Technical Specifications Marked-up Pages

Primary Containment Isolation Instrumentation 3.3.6.1 Table 3.3.6.1-1 (page 1 of 5)

Primary Containment Isolation Instrumentation APPLICABLE CONDITIONS MODES OR REQUIRED REFERENCED OTHER CHANNELS FROM SPECIFIED PER TRIP REQUIRED SURVEILLANCE ALLOWABLE FUNCTION CONDITIONS SYSTEM ACTION C.1 REQUIREMENTS VALUE

1. Main Steam Line Isolation
a. Reactor Vessel Water Level - 1,2,3 2 D SR 3.3.6.1.1 -113 inches Low Low Low, Level 1 SR 3.3.6.1.2 SR 3.3.6.1.5 SR 3.3.6.1.6
b. Main Steam Line Pressure - 1 2 E SR 3.3.6.1.3 825 psig Low SR 3.3.6.1.6
c. Main Steam Line 1,2,3 2 per D SR 3.3.6.1.1 138% rated Flow - High MSL SR 3.3.6.1.2 steam flow SR 3.3.6.1.5 SR 3.3.6.1.6
d. Condenser Vacuum - Low 1, 2 D SR 3.3.6.1.3 7 inches Hg 2(a), 3(a) SR 3.3.6.1.6 vacuum
e. Main Steam Tunnel 1,2,3 6 D SR 3.3.6.1.1 194°F Temperature - High SR 3.3.6.1.2 SR 3.3.6.1.5 SR 3.3.6.1.6
f. Turbine Building Area 1,2,3 16(b) D SR 3.3.6.1.2 200°F Temperature - High SR 3.3.6.1.5 SR 3.3.6.1.6
2. Primary Containment Isolation
a. Reactor Vessel Water Level 1,2,3 2 H 0 inches

- Low, Level 3 SR 3.3.6.1.1 SR 3.3.6.1.2 SR 3.3.6.1.5

b. Drywell Pressure - High 1,2,3 2 H SR 3.3.6.1.6 1.92 psig SR 3.3.6.1.1 SR 3.3.6.1.2 SR 3.3.6.1.5 SR 3.3.6.1.6 (continued)

(a) With any turbine stop valve not closed.

(b) With 8 channels per trip string. Each trip string shall have 2 channels per main steam line, with no more than 40 ft separating any two OPERABLE channels.

HATCH UNIT 1 3.3-55 Amendment No. 290

Primary Containment Isolation Instrumentation 3.3.6.1 Table 3.3.6.1-1 (page 4 of 5)

Primary Containment Isolation Instrumentation APPLICABLE CONDITIONS MODES OR REQUIRED REFERENCED OTHER CHANNELS FROM SPECIFIED PER TRIP REQUIRED SURVEILLANCE ALLOWABLE FUNCTION CONDITIONS SYSTEM ACTION C.1 REQUIREMENTS VALUE

4. RCIC System Isolation (continued)
g. RCIC Suppression Pool 1,2,3 1 F SR 3.3.6.1.1 42°F Area Differential SR 3.3.6.1.2 Temperature - High SR 3.3.6.1.5 SR 3.3.6.1.6
h. Emergency Area Cooler 1,2,3 1 F SR 3.3.6.1.1 169°F Temperature - High SR 3.3.6.1.2 SR 3.3.6.1.5 SR 3.3.6.1.6
5. RWCU System Isolation
a. Area Temperature - High 1,2,3 1 per area F SR 3.3.6.1.1 150°F SR 3.3.6.1.2 SR 3.3.6.1.5 SR 3.3.6.1.6
b. Area Ventilation 1,2,3 1 per area F SR 3.3.6.1.1 67°F Differential Temperature - SR 3.3.6.1.2 High SR 3.3.6.1.5 SR 3.3.6.1.6
c. SLC System Initiation 1,2 1(cb) I SR 3.3.6.1.6 NA
d. Reactor Vessel Water 1,2,3 2 F SR 3.3.6.1.1 -47 inches Level - Low Low, Level 2 SR 3.3.6.1.2 SR 3.3.6.1.5 SR 3.3.6.1.6
6. RHR Shutdown Cooling System Isolation
a. Reactor Steam Dome 1,2,3 1 F SR 3.3.6.1.1 145 psig Pressure - High SR 3.3.6.1.2 SR 3.3.6.1.5 SR 3.3.6.1.6
b. Reactor Vessel Water 3 2 J SR 3.3.6.1.1 0 inches Level - Low, Level 3 SR 3.3.6.1.2 SR 3.3.6.1.5 SR 3.3.6.1.6 (continued)

(cb) SLC System Initiation only inputs into one of the two trip systems.

HATCH UNIT 1 3.3-58 Amendment No. 290

Turbine Building (TB) Maximum Area Temperature 3.7.10 3.7 PLANT SYSTEMS 3.7.10 Turbine Building (TB) Maximum Area Temperature LCO 3.7.10 TB maximum area temperature shall be 200 °F.

APPLICABILITY: MODES 1, 2, and 3.

ACTIONS CONDITION REQUIRED ACTION COMPLETION TIME A. TB maximum area A.1 Initiate action to verify Immediately temperature no main steam line

> 200°F. leak.

AND A.2 Verify no main steam Once per 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> line leak. thereafter B. Required Action and B.1 Be in MODE 3. 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> associated Completion Time not met. AND B.2 Be in MODE 4. 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> SURVEILLANCE REQUIREMENTS SURVEILLANCE FREQUENCY SR 3.7.10.1 Verify TB maximum area temperature is 200 °F. In accordance with the Surveillance Frequency Control Program HATCH UNIT 1 3.7-22 Amendment No.

Primary Containment Isolation Instrumentation 3.3.6.1 Table 3.3.6.1-1 (page 1 of 5)

Primary Containment Isolation Instrumentation APPLICABLE CONDITIONS MODES OR REQUIRED REFERENCED OTHER CHANNELS FROM SPECIFIED PER TRIP REQUIRED SURVEILLANCE ALLOWABLE FUNCTION CONDITIONS SYSTEM ACTION C.1 REQUIREMENTS VALUE

1. Main Steam Line Isolation
a. Reactor Vessel Water 1,2,3 2 D SR 3.3.6.1.1 -113 inches Level - Low Low Low, SR 3.3.6.1.2 Level 1 SR 3.3.6.1.5 SR 3.3.6.1.6 SR 3.3.6.1.7
b. Main Steam Line 1 2 E SR 3.3.6.1.3 825 psig Pressure - Low SR 3.3.6.1.6
c. Main Steam Line 1,2,3 2 per D SR 3.3.6.1.1 138% rated Flow - High MSL SR 3.3.6.1.2 steam flow SR 3.3.6.1.5 SR 3.3.6.1.6 SR 3.3.6.1.7
d. Condenser Vacuum - Low 1, 2 D SR 3.3.6.1.3 7 inches Hg 2(a), 3(a) SR 3.3.6.1.6 vacuum
e. Main Steam Tunnel 1,2,3 6 D SR 3.3.6.1.1 194°F Temperature - High SR 3.3.6.1.2 SR 3.3.6.1.5 SR 3.3.6.1.6
f. Turbine Building Area 1,2,3 16(b) D SR 3.3.6.1.2 200°F Temperature - High SR 3.3.6.1.5 SR 3.3.6.1.6
2. Primary Containment Isolation
a. Reactor Vessel Water 1,2,3 2 H SR 3.3.6.1.1 0 inches Level - Low, Level 3 SR 3.3.6.1.2 SR 3.3.6.1.5 SR 3.3.6.1.6
b. Drywell Pressure -

High 1,2,3 2 H SR 3.3.6.1.1 1.92 psig SR 3.3.6.1.2 SR 3.3.6.1.5 SR 3.3.6.1.6 (continued)

(a) With any turbine stop valve not closed.

(b) With 8 channels per trip string. Each trip string shall have 2 channels per main steam line, with no more than 40 ft separating any two OPERABLE channels.

HATCH UNIT 2 3.3-55 Amendment No. 235

Primary Containment Isolation Instrumentation 3.3.6.1 Table 3.3.6.1-1 (page 4 of 5)

Primary Containment Isolation Instrumentation APPLICABLE CONDITIONS MODES OR REQUIRED REFERENCED OTHER CHANNELS FROM SPECIFIED PER TRIP REQUIRED SURVEILLANCE ALLOWABLE FUNCTION CONDITIONS SYSTEM ACTION C.1 REQUIREMENTS VALUE

4. RCIC System Isolation (continued)
g. RCIC Suppression Pool 1,2,3 1 F SR 3.3.6.1.1 42°F Area Differential SR 3.3.6.1.2 Temperature - High SR 3.3.6.1.5 SR 3.3.6.1.6
h. Emergency Area Cooler 1,2,3 1 F SR 3.3.6.1.1 169°F Temperature - High SR 3.3.6.1.2 SR 3.3.6.1.5 SR 3.3.6.1.6
5. RWCU System Isolation
a. Area Temperature - High 1,2,3 1 per area F SR 3.3.6.1.1 150°F SR 3.3.6.1.2 SR 3.3.6.1.5 SR 3.3.6.1.6
b. Area Ventilation 1,2,3 1 per area F SR 3.3.6.1.1 67°F Differential Temperature - SR 3.3.6.1.2 High SR 3.3.6.1.5 SR 3.3.6.1.6
c. SLC System Initiation 1,2 1(cb) I SR 3.3.6.1.6 NA
d. Reactor Vessel Water 1,2,3 2 F SR 3.3.6.1.1 - 47 inches Level - Low Low, Level 2 SR 3.3.6.1.2 SR 3.3.6.1.5 SR 3.3.6.1.6
6. RHR Shutdown Cooling System Isolation
a. Reactor Steam Dome 1,2,3 1 F SR 3.3.6.1.1 145 psig Pressure - High SR 3.3.6.1.2 SR 3.3.6.1.5 SR 3.3.6.1.6
b. Reactor Vessel Water 3 2 J SR 3.3.6.1.1 0 inches Level - Low, Level 3 SR 3.3.6.1.2 SR 3.3.6.1.5 SR 3.3.6.1.6 (continued)

(cb) SLC System Initiation only inputs into one of the two trip systems.

HATCH UNIT 2 3.3-58 Amendment No. 235

Turbine Building (TB) Maximum Area Temperature 3.7.10 3.7 PLANT SYSTEMS 3.7.10 Turbine Building (TB) Maximum Area Temperature LCO 3.7.10 TB maximum area temperature shall be 200 °F.

APPLICABILITY: MODES 1, 2, and 3.

ACTIONS CONDITION REQUIRED ACTION COMPLETION TIME A. TB maximum area A.1 Initiate action to verify Immediately temperature no main steam line

> 200°F. leak.

AND A.2 Verify no main steam Once per 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> line leak. thereafter B. Required Action and B.1 Be in MODE 3. 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> associated Completion Time not met. AND B.2 Be in MODE 4. 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> SURVEILLANCE REQUIREMENTS SURVEILLANCE FREQUENCY SR 3.7.10.1 Verify TB maximum area temperature is 200 °F. In accordance with the Surveillance Frequency Control Program HATCH UNIT 2 3.7-23 Amendment No.

Edwin I. Hatch Nuclear Plant - Units 1 and 2 Request to Eliminate Automatic Main Steam Line Isolation on High Turbine Building Area Temperature Attachment 2 HNP Unit 1 and Unit 2 Technical Specifications Revised TS Pages

Primary Containment Isolation Instrumentation 3.3.6.1 Table 3.3.6.1-1 (page 1 of 5)

Primary Containment Isolation Instrumentation APPLICABLE CONDITIONS MODES OR REQUIRED REFERENCED OTHER CHANNELS FROM SPECIFIED PER TRIP REQUIRED SURVEILLANCE ALLOWABLE FUNCTION CONDITIONS SYSTEM ACTION C.1 REQUIREMENTS VALUE

1. Main Steam Line Isolation
a. Reactor Vessel Water Level - 1,2,3 2 D SR 3.3.6.1.1 -113 inches Low Low Low, Level 1 SR 3.3.6.1.2 SR 3.3.6.1.5 SR 3.3.6.1.6
b. Main Steam Line Pressure - 1 2 E SR 3.3.6.1.3 825 psig Low SR 3.3.6.1.6
c. Main Steam Line 1,2,3 2 per D SR 3.3.6.1.1 138% rated Flow - High MSL SR 3.3.6.1.2 steam flow SR 3.3.6.1.5 SR 3.3.6.1.6
d. Condenser Vacuum - Low 1, 2 D SR 3.3.6.1.3 7 inches Hg 2(a), 3(a) SR 3.3.6.1.6 vacuum
e. Main Steam Tunnel 1,2,3 6 D SR 3.3.6.1.1 194°F Temperature - High SR 3.3.6.1.2 SR 3.3.6.1.5 SR 3.3.6.1.6
2. Primary Containment Isolation
a. Reactor Vessel Water Level 1,2,3 2 H SR 3.3.6.1.1 0 inches

- Low, Level 3 SR 3.3.6.1.2 SR 3.3.6.1.5 SR 3.3.6.1.6

b. Drywell Pressure - High 1,2,3 2 H SR 3.3.6.1.1 1.92 psig SR 3.3.6.1.2 SR 3.3.6.1.5 SR 3.3.6.1.6 (continued)

(a) With any turbine stop valve not closed.

HATCH UNIT 1 3.3-55 Amendment No.

Primary Containment Isolation Instrumentation 3.3.6.1 Table 3.3.6.1-1 (page 4 of 5)

Primary Containment Isolation Instrumentation APPLICABLE CONDITIONS MODES OR REQUIRED REFERENCED OTHER CHANNELS FROM SPECIFIED PER TRIP REQUIRED SURVEILLANCE ALLOWABLE FUNCTION CONDITIONS SYSTEM ACTION C.1 REQUIREMENTS VALUE

4. RCIC System Isolation (continued)
g. RCIC Suppression Pool 1,2,3 1 F SR 3.3.6.1.1 42°F Area Differential SR 3.3.6.1.2 Temperature - High SR 3.3.6.1.5 SR 3.3.6.1.6
h. Emergency Area Cooler 1,2,3 1 F SR 3.3.6.1.1 169°F Temperature - High SR 3.3.6.1.2 SR 3.3.6.1.5 SR 3.3.6.1.6
5. RWCU System Isolation
a. Area Temperature - High 1,2,3 1 per area F SR 3.3.6.1.1 150°F SR 3.3.6.1.2 SR 3.3.6.1.5 SR 3.3.6.1.6
b. Area Ventilation 1,2,3 1 per area F SR 3.3.6.1.1 67°F Differential Temperature - SR 3.3.6.1.2 High SR 3.3.6.1.5 SR 3.3.6.1.6
c. SLC System Initiation 1,2 1(b) I SR 3.3.6.1.6 NA
d. Reactor Vessel Water 1,2,3 2 F SR 3.3.6.1.1 -47 inches Level - Low Low, Level 2 SR 3.3.6.1.2 SR 3.3.6.1.5 SR 3.3.6.1.6
6. RHR Shutdown Cooling System Isolation
a. Reactor Steam Dome 1,2,3 1 F SR 3.3.6.1.1 145 psig Pressure - High SR 3.3.6.1.2 SR 3.3.6.1.5 SR 3.3.6.1.6
b. Reactor Vessel Water 3 2 J SR 3.3.6.1.1 0 inches Level - Low, Level 3 SR 3.3.6.1.2 SR 3.3.6.1.5 SR 3.3.6.1.6 (continued)

(b) SLC System Initiation only inputs into one of the two trip systems.

HATCH UNIT 1 3.3-58 Amendment No.

Turbine Building (TB) Maximum Area Temperature 3.7.10 3.7 PLANT SYSTEMS 3.7.10 Turbine Building (TB) Maximum Area Temperature LCO 3.7.10 TB maximum area temperature shall be 200 °F.

APPLICABILITY: MODES 1, 2, and 3.

ACTIONS CONDITION REQUIRED ACTION COMPLETION TIME A. TB maximum area A.1 Initiate action to verify Immediately temperature no main steam line

> 200°F. leak.

AND A.2 Verify no main steam Once per 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> line leak. thereafter B. Required Action and B.1 Be in MODE 3. 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> associated Completion Time not met. AND B.2 Be in MODE 4. 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> SURVEILLANCE REQUIREMENTS SURVEILLANCE FREQUENCY SR 3.7.10.1 Verify TB maximum area temperature is 200 °F. In accordance with the Surveillance Frequency Control Program HATCH UNIT 1 3.7-22 Amendment No.

Primary Containment Isolation Instrumentation 3.3.6.1 Table 3.3.6.1-1 (page 1 of 5)

Primary Containment Isolation Instrumentation APPLICABLE CONDITIONS MODES OR REQUIRED REFERENCED OTHER CHANNELS FROM SPECIFIED PER TRIP REQUIRED SURVEILLANCE ALLOWABLE FUNCTION CONDITIONS SYSTEM ACTION C.1 REQUIREMENTS VALUE

1. Main Steam Line Isolation
a. Reactor Vessel Water 1,2,3 2 D SR 3.3.6.1.1 -113 inches Level - Low Low Low, SR 3.3.6.1.2 Level 1 SR 3.3.6.1.5 SR 3.3.6.1.6 SR 3.3.6.1.7
b. Main Steam Line 1 2 E SR 3.3.6.1.3 825 psig Pressure - Low SR 3.3.6.1.6
c. Main Steam Line 1,2,3 2 per D SR 3.3.6.1.1 138% rated Flow - High MSL SR 3.3.6.1.2 steam flow SR 3.3.6.1.5 SR 3.3.6.1.6 SR 3.3.6.1.7
d. Condenser Vacuum - Low 1, 2 D SR 3.3.6.1.3 7 inches Hg 2(a), 3(a) SR 3.3.6.1.6 vacuum
e. Main Steam Tunnel 1,2,3 6 D SR 3.3.6.1.1 194°F Temperature - High SR 3.3.6.1.2 SR 3.3.6.1.5 SR 3.3.6.1.6
2. Primary Containment Isolation
a. Reactor Vessel Water 1,2,3 2 H SR 3.3.6.1.1 0 inches Level - Low, Level 3 SR 3.3.6.1.2 SR 3.3.6.1.5 SR 3.3.6.1.6
b. Drywell Pressure -

High 1,2,3 2 H SR 3.3.6.1.1 1.92 psig SR 3.3.6.1.2 SR 3.3.6.1.5 SR 3.3.6.1.6 (continued)

(a) With any turbine stop valve not closed.

HATCH UNIT 2 3.3-55 Amendment No.

Primary Containment Isolation Instrumentation 3.3.6.1 Table 3.3.6.1-1 (page 4 of 5)

Primary Containment Isolation Instrumentation APPLICABLE CONDITIONS MODES OR REQUIRED REFERENCED OTHER CHANNELS FROM SPECIFIED PER TRIP REQUIRED SURVEILLANCE ALLOWABLE FUNCTION CONDITIONS SYSTEM ACTION C.1 REQUIREMENTS VALUE

4. RCIC System Isolation (continued)
g. RCIC Suppression Pool 1,2,3 1 F SR 3.3.6.1.1 42°F Area Differential SR 3.3.6.1.2 Temperature - High SR 3.3.6.1.5 SR 3.3.6.1.6
h. Emergency Area Cooler 1,2,3 1 F SR 3.3.6.1.1 169°F Temperature - High SR 3.3.6.1.2 SR 3.3.6.1.5 SR 3.3.6.1.6
5. RWCU System Isolation
a. Area Temperature - High 1,2,3 1 per area F SR 3.3.6.1.1 150°F SR 3.3.6.1.2 SR 3.3.6.1.5 SR 3.3.6.1.6
b. Area Ventilation 1,2,3 1 per area F SR 3.3.6.1.1 67°F Differential Temperature - SR 3.3.6.1.2 High SR 3.3.6.1.5 SR 3.3.6.1.6
c. SLC System Initiation 1,2 1(b) I SR 3.3.6.1.6 NA
d. Reactor Vessel Water 1,2,3 2 F SR 3.3.6.1.1 - 47 inches Level - Low Low, Level 2 SR 3.3.6.1.2 SR 3.3.6.1.5 SR 3.3.6.1.6
6. RHR Shutdown Cooling System Isolation
a. Reactor Steam Dome 1,2,3 1 F SR 3.3.6.1.1 145 psig Pressure - High SR 3.3.6.1.2 SR 3.3.6.1.5 SR 3.3.6.1.6
b. Reactor Vessel Water 3 2 J SR 3.3.6.1.1 0 inches Level - Low, Level 3 SR 3.3.6.1.2 SR 3.3.6.1.5 SR 3.3.6.1.6 (continued)

(b) SLC System Initiation only inputs into one of the two trip systems.

HATCH UNIT 2 3.3-58 Amendment No.

Turbine Building (TB) Maximum Area Temperature 3.7.10 3.7 PLANT SYSTEMS 3.7.10 Turbine Building (TB) Maximum Area Temperature LCO 3.7.10 TB maximum area temperature shall be 200 °F.

APPLICABILITY: MODES 1, 2, and 3.

ACTIONS CONDITION REQUIRED ACTION COMPLETION TIME A. TB maximum area A.1 Initiate action to verify Immediately temperature no main steam line

> 200°F. leak.

AND A.2 Verify no main steam Once per 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> line leak. thereafter B. Required Action and B.1 Be in MODE 3. 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> associated Completion Time not met. AND B.2 Be in MODE 4. 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> SURVEILLANCE REQUIREMENTS SURVEILLANCE FREQUENCY SR 3.7.10.1 Verify TB maximum area temperature is 200 °F. In accordance with the Surveillance Frequency Control Program HATCH UNIT 2 3.7-23 Amendment No.

Edwin I. Hatch Nuclear Plant - Units 1 and 2 Request to Eliminate Automatic Main Steam Line Isolation on High Turbine Building Area Temperature Attachment 3 HNP Unit 1 and Unit 2 Technical Specifications Bases Marked-up Pages (Information Only)

Primary Containment Isolation Instrumentation B 3.3.6.1 BASES BACKGROUND 1. Main Steam Line Isolation (continued) reactor water sample valves. The MSL drain line has two isolation valves with one two-out-of-two logic system associated with each valve. The reactor water sample line also has two isolation valves with similar logic.

The exceptions to this arrangement are the Main Steam Line Flow - High Function and Area Temperature Functions. The Main Steam Line Flow - High Function uses 16 flow channels, four for each steam line. One channel from each steam line inputs to one of the four trip strings. Two trip strings make up each trip system and both trip systems must trip to cause an MSL isolation. Each trip string has four inputs (one per MSL), any one of which will trip the trip string.

The trip strings are arranged in a one-out-of-two taken twice logic.

This is effectively a one-out-of-eight taken twice logic arrangement to initiate isolation of the MSIVs. Similarly, the 16 flow channels are connected into two two-out-of-two logic trip systems (effectively, two one-out-of-four twice logic), with each trip system isolating one of the two MSL drain valves and one of the two reactor water sample valves.

The Main Steam Tunnel Temperature - High Function receives input from 16 channels. The logic is arranged similar to the Main Steam Line Flow - High Function. The Turbine Building Area Temperature -

High Function receives input from 64 channels. Four channels from each steam line inputs to one of the four trip strings. Two trip strings make up each trip system and both trip systems must trip to cause an MSL isolation. Each trip string has 16 inputs (4 per MSL), any one of which will trip the trip string. The trip strings are arranged in a one-out-of-two taken twice logic. This is effectively a one-out-of-thirty-two taken twice logic trip system to isolate all MSIVs. Similarly, the inputs are arranged in two one-out-of-sixteen twice logic trip systems, with each trip system isolating one of the two MSL drain valves and one of the two reactor water sample valves.

MSL Isolation Functions isolate the Group 1 valves.

2. Primary Containment Isolation Most Primary Containment Isolation Functions receive inputs from four channels. The outputs from these channels are arranged into two two-out-of-two logic trip systems. One trip system initiates isolation of all inboard primary containment isolation valves, while the other trip system initiates isolation of all outboard primary containment isolation valves. Each logic closes one of the two valves on each (continued)

HATCH UNIT 1 B 3.3-143 REVISION 115

Primary Containment Isolation Instrumentation B 3.3.6.1 BASES APPLICABLE 1.e., 1.f. Main Steam Tunnel Area Temperature - High SAFETY ANALYSES, LCO, and Area Main Steam Tunnel temperature is provided to detect a leak in APPLICABILITY the RCPB and provides diversity to the high flow instrumentation. The (continued) isolation occurs when a very small leak has occurred. If the small leak is allowed to continue without isolation, offsite dose limits may be reached. However, credit for these instruments is not taken in any transient or accident analysis in the FSAR, since bounding analyses are performed for large breaks, such as MSLBs.

Area tTemperature signals are initiated from RTDs (for the Main Steam Tunnel Temperature - High Function) or temperature switches (for the Turbine Building Area Temperature - High Function) located in the area being monitoredmain steam tunnel. While 16 channels of Main Steam Tunnel Temperature - High Function are available, only 12 channels (6 per trip system) are required to be OPERABLE. This will ensure that no single instrument failure can preclude the isolation function, assuming a line break on any line (the instruments assigned to monitor one line can still detect a leak on another line due to their close proximity to one another and the small confines of the area).

While 64 channels of Turbine Building Area Temperature - High Function are available, only 32 channels are required to be OPERABLE to ensure that no single instrument failure can preclude the isolation function. Each channel has one temperature element.

The 32 channel requirement is further divided up, as noted in footnote (b), into 16 channels per trip system with 8 per trip string. Each trip string shall have 2 channels per main steam line, with no more than 40 feet separating any two OPERABLE channels. In addition, no unmonitored area should exceed 40 feet in length.

The ambient temperature monitoring Allowable Value is chosen to detect a leak equivalent to between 1% and 10% rated steam flow.

These This Functions isolates the Group 1 valves.

2. Primary Containment Isolation 2.a. Reactor Vessel Water Level - Low, Level 3 Low RPV water level indicates that the capability to cool the fuel may be threatened. The valves whose penetrations communicate with the primary containment are isolated to limit the release of fission products. The isolation of the primary containment on Level 3 supports actions to ensure that offsite dose limits of 10 CFR 50.67 are not exceeded. The Reactor Vessel Water Level - Low, Level 3 (continued)

HATCH UNIT 1 B 3.3-151 REVISION 115

Turbine Building (TB) Maximum Area Temperature B 3.7.10 B 3.7 PLANT SYSTEMS B 3.7.10 Turbine Building (TB) Maximum Area Temperature BASES BACKGROUND Main Steam Line (MSL) leakage is limited to ensure that the accident analyses demonstrate that the offsite and control room dose limits are met. For purposes of this Technical Specification, MSL leakage is defined as leakage from any of the four MSLs or any unisolable branch off the MSL in the area from the Main Steam Isolation Valves (MSIVs) up to the steam chests. Direct detection of small amounts of MSL leakage is not practical, so monitoring the area temperatures near the MSLs is used as a surrogate indication of an MSL leak. The turbine building (TB) maximum area temperature monitoring also provides diversity to the MSL high flow instrumentation which will detect a large MSL leak.

The TB area temperature is monitored by 64 temperature elements arranged to monitor all of the MSLs. The temperature elements are placed so that no more than 40 feet separates any two temperature elements to ensure that no areas are unmonitored.

APPLICABLE Area temperature monitoring is provided to detect small MSL leakage SAFETY ANALYSES (between 1% and 10% of rated steam flow) in the condenser bay area of the TB. Should a large MSL break occur, the main steam isolation valves (MSIVs) will automatically close based on a Main Steam Line Flow - High signal.

Analyses are performed for large MSL breaks, such as the Main Steam Line Break (MSLB) accident, but small amounts MSL leakage in the TB is not considered in other design basis accident (DBA) or transient analyses. As a result, small MSL leaks in the TB could result in post-accident doses that may exceed the analyzed values. To prevent this from occurring, the TB is monitored for MSL leakage and steps are taken to correct the condition if a small MSL leak is detected. This preserves the initial conditions assumed in the DBA and transient analyses.

TB maximum area temperature satisfies Criterion 2 of 10 CFR 50.36(c)(2)(ii).

LCO The TB maximum area temperature limit of 200°F ensures there is not an MSL leak in the TB. The limit of 200°F is based on detecting an MSL leak equivalent to 1% to 10% of rated steam flow and ensures that small MSL leaks will be detected and corrected.

(continued)

HATCH UNIT 1 B 3.7-49 REVISION

Turbine Building (TB) Maximum Area Temperature B 3.7.10 BASES APPLICABILITY In MODES 1, 2, and 3, a DBA could result in the release of radioactive material into the TB if there is a leak in the MSLs. In MODES 4 and 5, the probability and consequences of a DBA with fission product release into the TB are reduced because of the pressure and temperature limitations in these MODES. Therefore, maintaining TB area temperature within limits is not required in MODE 4 or 5.

ACTIONS A.1 and A.2 If TB maximum area temperature exceeds 200°F, immediate action must be taken to confirm there is no MSL leak into the TB. Indications of a small MSL leak in the turbine building include, but are not limited to:

  • An unexpected, sudden rise in area temperature,
  • An unexpected increase in radiation monitor readings,
  • An unexpected rise in turbine building sump levels,
  • An unexpected decrease in plant electrical output, and
  • Visual and sound indications.

TB area temperature may be elevated due to reasons other than an MSL leak, such as hot weather, reduced turbine building area chiller capacity, other leaks (i.e., not MSL leakage) in the turbine building (e.g.,

leaks past seals, packing and gaskets), and faulty temperature detectors.

If the TB maximum area temperature exceeds 200°F, verification that no MSL leak exists must be performed periodically. The 12-hour Completion Time is acceptable considering the likelihood of a MSL leak occurring.

B.1 and B.2 If it cannot be confirmed that no MSL leak in the TB exists or the periodic verification is not performed, 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 at least MODE 3 within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and to MODE 4 within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />. The allowed Completion Times are reasonable, based on operating experience, to reach the required plant conditions from full power conditions in an orderly manner and without challenging plant systems.

(continued)

HATCH UNIT 1 B 3.7-50 REVISION

Turbine Building (TB) Maximum Area Temperature B 3.7.10 BASES SURVEILLANCE SR 3.7.10.1 REQUIREMENTS Verification that the maximum area temperature is 200°F ensures there is no MSL leak in the TB. In order to ensure timely detection of an MSL leak, each MSL must be monitored with sufficient detectors to ensure no more than 40 feet separates two in-service temperature elements.

The TB area temperature alarm function is not required for this SR to be met.

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

REFERENCES None.

HATCH UNIT 1 B 3.7-51 REVISION

Primary Containment Isolation Instrumentation B 3.3.6.1 BASES BACKGROUND 1. Main Steam Line Isolation (continued) reactor water sample valves. The MSL drain line has two isolation valves with one two-out-of-two logic system associated with each valve. The reactor water sample line also has two isolation valves with similar logic.

The exceptions to this arrangement are the Main Steam Line Flow - High Function and Area Temperature Functions. The Main Steam Line Flow - High Function uses 16 flow channels, four for each steam line. One channel from each steam line inputs to one of the four trip strings. Two trip strings make up each trip system and both trip systems must trip to cause an MSL isolation. Each trip string has four inputs (one per MSL), any one of which will trip the trip string.

The trip strings are arranged in a one-out-of-two taken twice logic.

This is effectively a one-out-of-eight taken twice logic arrangement to initiate isolation of the MSIVs. Similarly, the 16 flow channels are connected into two two-out-of-two logic trip systems (effectively, two one-out-of-four twice logic), with each trip system isolating one of the two MSL drain valves and one of the two reactor water sample valves.

The Main Steam Tunnel Temperature - High Function receives input from 16 channels. The logic is arranged similar to the Main Steam Line Flow - High Function. The Turbine Building Area Temperature -

High Function receives input from 64 channels. Four channels from each steam line inputs to one of the four trip strings. Two trip strings make up each trip system and both trip systems must trip to cause an MSL isolation. Each trip string has 16 inputs (4 per MSL), any one of which will trip the trip string. The trip strings are arranged in a one-out-of-two taken twice logic. This is effectively a one-out-of-thirty-two taken twice logic trip system to isolate all MSIVs. Similarly, the inputs are arranged in two one-out-of-sixteen twice logic trip systems, with each trip system isolating one of the two MSL drain valves and one of the two reactor water sample valves.

MSL Isolation Functions isolate the Group 1 valves.

2. Primary Containment Isolation Most Primary Containment Isolation Functions receive inputs from four channels. The outputs from these channels are arranged into two two-out-of-two logic trip systems. One trip system initiates isolation of all inboard primary containment isolation valves, while the other trip system initiates isolation of all outboard primary containment isolation valves. Each logic closes one of the two valves on each (continued)

HATCH UNIT 2 B 3.3-143 REVISION 127

Primary Containment Isolation Instrumentation B 3.3.6.1 BASES APPLICABLE 1.e., 1.f. Main Steam Tunnel Area Temperature - High SAFETY ANALYSES, LCO, and AreaMain Steam Tunnel temperature is provided to detect a leak in APPLICABILITY the RCPB and provides diversity to the high flow instrumentation. The (continued) isolation occurs when a very small leak has occurred. If the small leak is allowed to continue without isolation, offsite dose limits may be reached. However, credit for these instruments is not taken in any transient or accident analysis in the FSAR, since bounding analyses are performed for large breaks, such as MSLBs.

Area tTemperature signals are initiated from RTDs (for the Main Steam Tunnel Temperature - High Function) or a thermocouple/temperature switch combination (for the Turbine Building Area Temperature - High Function) located in the area being monitoredmain steam tunnel.

While 16 channels of Main Steam Tunnel Temperature - High Function are available, only 12 channels (6 per trip system) are required to be OPERABLE. This will ensure that no single instrument failure can preclude the isolation function, assuming a line break on any line (the instruments assigned to monitor one line can still detect a leak on another line due to their close proximity to one another and the small confines of the area). While 64 channels of Turbine Building Area Temperature - High Function are available, only 32 channels are required to be OPERABLE to ensure that no single instrument failure can preclude the isolation function. Each channel has one temperature element. The 32 channel requirement is further divided up, as noted in footnote (b), into 16 channels per trip system with 8 per trip string. Each trip string shall have 2 channels per main steam line, with no more than 40 feet separating any two OPERABLE channels.

In addition, no unmonitored area should exceed 40 feet in length.

The ambient temperature monitoring Allowable Value is chosen to detect a leak equivalent to between 1% and 10% rated steam flow.

These This Functions isolates the Group 1 valves.

2. Primary Containment Isolation 2.a. Reactor Vessel Water Level - Low, Level 3 Low RPV water level indicates that the capability to cool the fuel may be threatened. The valves whose penetrations communicate with the primary containment are isolated to limit the release of fission products. The isolation of the primary containment on Level 3 supports actions to ensure that offsite dose limits of 10 CFR 50.67 are not exceeded. The Reactor Vessel Water Level - Low, Level 3 (continued)

HATCH UNIT 2 B 3.3-150 REVISION 127

Turbine Building (TB) Maximum Area Temperature B 3.7.10 B 3.7 PLANT SYSTEMS B 3.7.10 Turbine Building (TB) Maximum Area Temperature BASES BACKGROUND Main Steam Line (MSL) leakage is limited to ensure that the accident analyses demonstrate that the offsite and control room dose limits are met. For purposes of this Technical Specification, MSL leakage is defined as leakage from any of the four MSLs or any unisolable branch off the MSL in the area from the Main Steam Isolation Valves (MSIVs) up to the steam chests. Direct detection of small amounts of MSL leakage is not practical, so monitoring the area temperatures near the MSLs is used as a surrogate indication of an MSL leak. The turbine building (TB) maximum area temperature monitoring also provides diversity to the MSL high flow instrumentation which will detect a large MSL leak.

The TB area temperature is monitored by 64 temperature elements arranged to monitor all of the MSLs. The temperature elements are placed so that no more than 40 feet separates any two temperature elements to ensure that no areas are unmonitored.

APPLICABLE Area temperature monitoring is provided to detect small MSL leakage SAFETY ANALYSES (between 1% and 10% of rated steam flow) in the condenser bay area of the TB. Should a large MSL break occur, the main steam isolation valves (MSIVs) will automatically close based on a Main Steam Line Flow - High signal.

Analyses are performed for large MSL breaks, such as the Main Steam Line Break (MSLB) accident, but small amounts MSL leakage in the TB is not considered in other design basis accident (DBA) or transient analyses. As a result, small MSL leaks in the TB could result in post-accident doses that may exceed the analyzed values. To prevent this from occurring, the TB is monitored for MSL leakage and steps are taken to correct the condition if a small MSL leak is detected. This preserves the initial conditions assumed in the DBA and transient analyses.

TB maximum area temperature satisfies Criterion 2 of 10 CFR 50.36(c)(2)(ii).

LCO The TB maximum area temperature limit of 200°F ensures there is not an MSL leak in the TB. The limit of 200°F is based on detecting an MSL leak equivalent to 1% to 10% of rated steam flow and ensures that small MSL leaks will be detected and corrected.

(continued)

HATCH UNIT 2 B 3.7-49 REVISION

Turbine Building (TB) Maximum Area Temperature B 3.7.10 BASES APPLICABILITY In MODES 1, 2, and 3, a DBA could result in the release of radioactive material into the TB if there is a leak in the MSLs. In MODES 4 and 5, the probability and consequences of a DBA with fission product release into the TB are reduced because of the pressure and temperature limitations in these MODES. Therefore, maintaining TB area temperature within limits is not required in MODE 4 or 5.

ACTIONS A.1 and A.2 If TB maximum area temperature exceeds 200°F, immediate action must be taken to confirm there is no MSL leak into the TB. Indications of a small MSL leak in the turbine building include, but are not limited to:

  • An unexpected, sudden rise in area temperature,
  • An unexpected increase in radiation monitor readings,
  • An unexpected rise in turbine building sump levels,
  • An unexpected decrease in plant electrical output, and
  • Visual and sound indications.

TB area temperature may be elevated due to reasons other than an MSL leak, such as hot weather, reduced turbine building area chiller capacity, other leaks (i.e., not MSL leakage) in the turbine building (e.g.,

leaks past seals, packing and gaskets), and faulty temperature detectors.

If the TB maximum area temperature exceeds 200°F, verification that no MSL leak exists must be performed periodically. The 12-hour Completion Time is acceptable considering the likelihood of a MSL leak occurring.

B.1 and B.2 If it cannot be confirmed that no MSL leak in the TB exists or the periodic verification is not performed, 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 at least MODE 3 within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and to MODE 4 within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />. The allowed Completion Times are reasonable, based on operating experience, to reach the required plant conditions from full power conditions in an orderly manner and without challenging plant systems.

(continued)

HATCH UNIT 2 B 3.7-50 REVISION

Turbine Building (TB) Maximum Area Temperature B 3.7.10 BASES SURVEILLANCE SR 3.7.10.1 REQUIREMENTS Verification that the maximum area temperature is 200°F ensures there is no MSL leak in the TB. In order to ensure timely detection of an MSL leak, each MSL must be monitored with sufficient detectors to ensure no more than 40 feet separates two in-service temperature elements.

The TB area temperature alarm function is not required for this SR to be met.

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

REFERENCES None.

HATCH UNIT 2 B 3.7-51 REVISION

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