2CAN060501, License Amendment Request Relocation of SDC OPI License Condition to TRM

License Amendment Request Relocation of SDC OPI License Condition to TRM

ML051890052
Person / Time
Site:	Arkansas Nuclear
Issue date:	06/29/2005
From:	Forbes J Entergy Operations
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
2CAN060501, TAC MC3799
Download: ML051890052 (10)

Text

Entergy Operations, Inc.

- Entergy 1448 S.R. 333 Russeliville, AR 72802 Tel 479-858-4888 Jeffery S. Forbes Vice President Operations ANO 2CAN060501 June 29, 2005 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555

SUBJECT:

License Amendment Request Relocation of SDC OPI License Condition to TRM Arkansas Nuclear One, Unit 2 Docket No. 50-368 License No. NPF-6

REFERENCES:

1. Entergy letter to the NRC dated July 8, 2004, "Shutdown Cooling Automatic Closure Interlock Removal" (2CAN070401)

2. Entergy letter to the NRC dated March 28, 2005, 'Supplement to Amendment Request For Shutdown Cooling Automatic Closure Interlock Removal" (2CAN030508)

3. NRC letter to Jeffery S. Forbes dated March 30, 2005, 'Issuance of Amendment RE: Removal of Shutdown Cooling Automatic Closure Interlock (AC) (TAC No. MC3799)" (2CNA030507)

Dear Sir or Madam:

Pursuant to 10 CFR 50.90, Entergy Operations, Inc. (Entergy) hereby requests the following amendment for Arkansas Nuclear One, Unit 2 (ANO-2). Entergy proposes to relocate the License Condition associated with the Shutdown Cooling (SDC) Open Permissive Interlock (OPI) to the Technical Requirements Manual. The NRC approved Standard Technical Specifications, Combustion Engineering Plants (NUREG-1432) includes a surveillance requirement for this function due to the complexity and differences of plant designs, which would not support complete removal of the function from the NUREG. For ANO-2, however, the OPI is not an assumed function that supports the accident analysis and does not meet the 10 CFR 50.36 criteria for inclusion in the TSs.

In letter dated July 8, 2004 (Reference 1), Entergy requested deletion of the Automatic Closure Interlock (ACI) and OPI functions associated with the SDC system motor-operated suction valves to support the ANO-2 refueling outage 2R1 7. However, the NRC did not have sufficient time to consider the permanent removal of the OPI function. Therefore, Entergy revised its request to maintain the OPI function as a condition of the Operating License and committed (Reference 2) to submit justification for removal of this function under separate letter. The removal of the ACI function was subsequently approved by NRC letter dated March 30, 2005 (Reference 3). b

'1~0

l 2CAN060501 Page 2 of 2 The proposed change has been evaluated in accordance with 10 CFR 50.91 (a)(1) using criteria in 10 CFR 50.92(c) and it has been determined that this change involves no significant hazards consideration. The bases for these determinations are included in the attached submittal.

The proposed change includes no new commitments.

Once approved, the amendment shall be implemented within 60 days. Although this request is neither exigent nor emergency, your prompt review is requested. Entergy requests approval of this amendment by July 1, 2006.

If you have any questions or require additional information, please contact David Bice at 479-858-5338.

I declare under penalty of perjury that the foregoing is true and correct. Executed on June 29, 2005.

Sincerely, JSF/dbb Attachments: Analysis of Proposed Technical Specification Change cc: Dr. Bruce S. Mallett Regional Administrator U. S. Nuclear Regulatory Commission Region IV 611 Ryan Plaza Drive, Suite 400 Arlington, TX 76011-8064 NRC Senior Resident Inspector Arkansas Nuclear One P. O. Box 310 London, AR 72847 U. S. Nuclear Regulatory Commission Attn: Mr. Drew G. Holland MS O-7D1 Washington, DC 20555-0001 Mr. Bernard R. Bevill Director Division of Radiation Control and Emergency Management Arkansas Department of Health 4815 West Markham Street Little Rock, AR 72205

Attachment to 2CAN060501 Analysis of Proposed Technical Specification Change

Attachment to 2CAN060501 Page 1 of 7

1.0 DESCRIPTION

This letter is a request to amend Operating License NPF-6 for Arkansas Nuclear One, Unit 2 (ANO-2).

The proposed change will revise the Operating License to relocate the requirement to maintain an Open Permissive Interlock (OPI) associated with the Shutdown Cooling (SDC) system motor-operated suction valves to the Technical Requirements Manual (TRM).

2.0 PROPOSED CHANGE

The proposed change will relocate the SDC OPI function from the Operating License to the TRM. A License Condition to maintain the operability of the OPI had previously been incorporated into the Operating License via NRC letter dated March 30, 2005 (Reference 1).

The NRC approved Standard Technical Specifications, Combustion Engineering Plants (NUREG-1432) include a requirement for the OPI function due to the complexity and differences of plant designs, which would not support complete removal of the function from the NUREG. For ANO-2, however, the OPI is not an assumed function that supports the accident analysis and does not meet the 10 CFR 50.36 criteria for inclusion in the Technical Specifications (TSs). Reference to NUREG-1432 will henceforth be referred to as Improved Technical Specifications or ITS.

3.0 BACKGROUND

The SDC System is designed as a low pressure system. The SDC suction line inside containment contains two normally de-energized locked-closed motor operated valves in series, ensuring that the low pressure piping is not exposed to normal Reactor Coolant System (RCS) pressure. Administrative controls, procedures and interlocks prevent opening these valves before the RCS has been depressurized. Key-operated control switches are provided in the control room to permit opening of the isolation valves. Interlocks prevent the valves from being opened unless RCS pressure is below 400 psia (OPI). Inadvertent operation of one of these normally locked closed motor operated gate valves at elevated RCS pressures would have no effect on operating events or sequences. System configuration is illustrated simplistically below:

Reactor Coolant Hot Leg opi M iToSDC Pumps

\ Containment Boundary

Attachment to 2CAN060501 Page 2 of 7 Two diverse restricted-range pressure measurement channels provide a control room indication of RCS pressure during plant startup and shutdown. These pressure channels provide signals to the two SDC suction isolation valves inside containment (which are prevented by the OPI from opening above a selected setpoint) and the safety injection tank (SIT) isolation valves (to ensure they are open). For the SDC OPI function, loss of electric power to either pressure measurement channel will prevent the valve from being opened by remote-manual means.

A detailed description of the operation of the SDC OPI function is included in Section 7.6.1.1 of the ANO-2, Safety Analysis Report (Reference 4).

4.0 TECHNICAL ANALYSIS

Licensees are required to maintain sufficient administrative controls over plant processes to support continued operability of plant equipment. For example, when isolating a pump for maintenance, administrative controls ensure the pump discharge valve is closed prior to the pump suction valve. This precaution prevents possible over-pressurization of the pump suction that could be exposed to system discharge pressure if the valves were closed in reverse order. Such administrative controls are an expectation for each licensee to protect plant systems and equipment from unnecessary damage and are rarely considered for inclusion in plants TSs, provided plant risk is maintained minimal.

As illustrated in the previous section of this attachment, three in-series, motor-operated valves (MOVs) are installed between the RCS and the SDC system, although only the two inside-containment valves are credited to prevent overpressurization of system piping. Each of these valves is normally de-energized closed during plant operation above Mode 5, except when SDC is in service in Mode 4. The valve position for each MOV is indicated in the control room. Valve manipulation is accomplished via a key-operated control switch. The keys required to operate each control switch are strictly controlled and are normally removed.

Site procedures provide significant guidance, caution, and limits associated with operation of the SDC MOVs. Inadvertent operation of both inside-containment MOVs is required to expose the SDC penetration piping to elevated RCS pressures. As illustrated above, the penetration piping contains a relief valve to aid in minimizing over-pressurization effects although the relief capacity is not sufficient to protect the piping with both inside-containment MOVs open at RCS operating pressure. Inadvertent operation of at least the two inside-containment SDC suction MOVs is required to expose suction piping from the penetration to the normally locked-closed Low Pressure Safety Injection (LPSI) pump manual suction valve.

The LPSI system itself is not impacted by inadvertent operations of the three SDC suction MOVs since the manual suction valve is locked-closed above SDC operating pressure.

Because numerous physical and procedural controls bound the operation of these MOVs, the OPI function is not required for protection of the ANO-2 SDC piping.

Although Reactor Systems Branch Technical Position (BTP) 5-1 (Reference 6) describes the OPI function, there are no specific regulatory guides or General Design Criteria (GDC) which apply to the OPI function. The interlock serves no protective function during abnormal or accident situations, as defined in IEEE 279-1971. The requirements of IEEE 279-1971 are written expressly for protection systems, and as such, they are not directly applicable to this interlock.

il Attachment to 2CAN060501 Page 3 of 7 ANO-2 currently maintains a SDC suction pressure alarm with audible and visual indication in the control room to alert operators if RCS pressure is increased above setpoint when SDC is aligned. The setpoint is administratively controlled. A control room annunciator will also illuminate and sound when either of the two inside-containment SDC system suction valves is not fully closed when RCS pressure is above the OPI setpoint. The current in-plant setpoint value established for OPI is well below the SDC system design pressure and 50 psi below that allowed by the current License Condition. The alarm obtains its valve position input from a source independent of valve control functions or position indication (e.g., spare rotor). The alarm is also independent of the valve's normal power supply and fails in the alarm state on loss of power. In addition to this control board panel alarm, other SDC-related alarm functions are maintained and annunciated by plant computers, including the required Safety Parameter Display System (SPDS) computer. An example of such alarming capability is a setting for SDC pump discharge pressure (discharge pressure increases as RCS pressure increases) and the low range RCS pressure indicators presented in the Background Section above. In summary, the status of the SDC system is considered of great importance and is extensively monitored anytime the system is in service.

As stated previously, the ITS includes requirements for the OPI function (Reference 5).

These requirements were intended to prevent inadvertent mis-positioning of SDC suction valves that separate the normally high pressure RCS from the low pressure SDC system.

Exposing the SDC system to high RCS pressures could result in an Event V (outside containment) intersystem loss of coolant accident (ISLOCA) and subsequent release of radiological fluid outside the containment building. Because the SDC systems of nuclear generating facilities can differ greatly in specific design, it is appropriate for these requirements to be presented in the ITS to ensure this high - low pressure interface remains protected. However, the design of the ANO-2 SDC system and supporting equipment, coupled with station procedures and strict administrative controls provide sufficient assurance that the SDC system will not be inadvertently exposed to pressures above system design. If the SDC suction valves were not locked closed, exposing the SDC system to high RCS pressures would require (1) removal or disregard for danger tags installed on power supplies, (2) closure of power supply breakers, (3) a key (for the key operated hand switch on the control board), and (4) opening of at least the two inside-containment valves. The OPI function is, therefore, not required to provide this protection with regard to the ANO-2 facility.

Although the OPI function will be relocated to the TRM, continued safe operation is not contingent on the continued operability of the OPI function.

The following provides a review of the criteria set forth in 10 CFR 50.36 for TS limiting condition for operations to justify the removal of the SDC OPI function from the TS. In addition, justification for excluding the SDC OPI function from the TSs is provided with regard to the criteria set forth in 10 CFR 50.36.

Criterion I - Installed instrumentation that is used to detect, and indicate in the control room, a significant abnormal degradation of the reactor coolant pressure boundary.

Two diverse restricted-range pressure measurement channels provide a control room indication of RCS pressure during plant startup and shutdown in the control room. The operability of the SDC OPI function will not affect these indications. The SDC OPI function is not part of installed instrumentation used to detect abnormal degradation of the RCS pressure boundary.

Attachment to 2CAN060501 Page 4 of 7 Criterion 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.

A review of the Safety Analysis Report (SAR) Chapter 15 accident analysis concluded that the SDC OPI function is not credited in the mitigation or prevention of any accidents and, therefore, does not meet the criteria set forth in 10 CFR 50.36(c)(2)(ii), Criterion 2, for inclusion in the TSs.

Criterion 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.

A review of the SAR Chapter 15 accident analysis concluded that the SDC OPI function is not credited in the mitigation or prevention of any accidents and, therefore, does not meet the criteria set forth in 10 CFR 50.36(c)(2)(ii),

Criterion 3, for inclusion in the TSs.

Criterion 4 - A structure, system, or component which operating experience or probabilistic risk assessment has shown to be significant to public health and safety.

The SDC OPI function is considered to be an insignificant risk contributor to the core damage frequency and offsite dose assessment. Because a variety of strict procedural, administrative, and design controls must be violated to align the SDC system during normal plant operation, no credible risk impact exists for operation above SDC transition periods. Finally, the OPI function is not credited in any accident analysis.

Biblis-A ISLOCA Event of December 1987 In addition to the above the NRC, in a January 1989 meeting with the CE Owners Group, requested that each plant requesting removal of the SDC ACI function evaluate their specific plant design and controls against the December 1987 Biblis-A ISLOCA Event. In the Biblis-A event of 1987, an operator attempted to close a mis-positioned pressure isolation valve that should have been closed prior to startup. To support valve closure, the operator attempted to manage the pressure differential across the valve by opening a second valve. In doing so, a path from the RCS to atmosphere was established resulting in a short term release. Because the OPI function is related to the ACI function, Entergy has evaluated the relocation of OPI to the TRM against the Biblis-A event below.

With regard to the RCSISDC suction interface, the requirement to obtain keys in order to operate the valves, the necessity to energize administratively controlled circuit breakers, and the fact that all three SDC suction MOVs are locked closed by procedure after securing the SDC system in preparation for plant heatup provide adequate assurance the valves will remain closed. Therefore, it is not assumed that an operator could inadvertently bypass these redundant controls to open any of the SDC suction MOVs during normal plant operation.

Attachment to 2CAN060501 Page 5 of 7 Summary As stated above, the SDC MOVs are locked and danger-tagged closed during normal operation. Valve position indication remains available in the Control Room even with power removed from the circuits. Keys used to operate the remote control switches in the Control Room are strictly controlled by the Shift Manager. The affected MOVs are additionally located inside containment which further limits the probability of inadvertent local operation (note that OPI would not prevent local operation of the valves). Although the numerous physical and administrative controls eliminate the need for an OPI function, Entergy has no current plans to physically disable the OPI function. The requirement to maintain the OPI function will be relocated to the TRM, which is part of the ANO-2 Safety Analysis Report (SAR) and controlled under 10 CFR 50.59. Because the OPI function is not credited in the accident analysis and subsequently does not meet the criteria of 10 CFR 50.36 for inclusion in the TSs, Entergy considers the relocation of OPI requirements to the TRM acceptable.

5.0 REGULATORY ANALYSIS

5.1 Applicable Reaulatory Requirements/Criteria The proposed change has been evaluated to determine whether applicable regulations and requirements continue to be met. Entergy has determined that the proposed changes do not require any exemptions or relief from regulatory requirements, other than the Technical Specifications (TS), and do not affect conformance with any General Design Criterion (GDC) differently than described in the Safety Analysis Report (SAR).

5.2 No Significant Hazards Consideration Entergy proposes to relocate the Arkansas Nuclear One, Unit 2 (ANO-2) License Condition associated with the Open Permissive Interlock (OPI) of the Shutdown Cooling (SDC) suction isolation valves to the Technical Requirements Manual (TRM).

Entergy Operations, Inc. has evaluated whether or not a significant hazards consideration is involved with the proposed amendment by focusing on the three standards set forth in 10 CFR 50.92, 'Issuance of amendment," as discussed below:

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

Response: No.

The OPI function is not required to ensure continued safe operation of the ANO-2 facility.

The OPI function is not considered an accident precursor or relied upon as a means of accident mitigation. The proposed change has no affect on plant design or operation.

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

a Attachment to 2CAN060501 Page 6 of 7

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

Response: No.

The relocation of the OPI function to the TRM does not require any physical alteration to the plant or alter plant design. The OPI function is not considered an accident initiator nor is this function credited in any safety analyses for the prevention or mitigation of any 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 OPI function is not credited in a margin of safety analysis for any accident previously evaluated. Relocation of the OPI function requirements will not result in a credible increase in nuclear safety risk. Appropriate alarm, design features, and administrative controls continue to ensure proper isolation of the SDC system during plant operations with elevated RCS pressures. In addition, the OPI function will be relocated to the TRM, which is part of the Safety Analysis Report (SAR) and controlled by 10 CFR 50.59.

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

Based on the above, Entergy 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.

5.3 Environmental Considerations The proposed amendment does not involve (i) a significant hazards consideration, (ii) a significant change in the types or significant increase in the amounts of any effluent 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.

6.0 PRECEDENCE None.

Attachment to 2CAN060501 Page 7 of 7

7.0 REFERENCES

1. NRC letter to Jeffery S. Forbes dated March 30, 2005, 'Issuance of Amendment RE:

Removal of Shutdown Cooling Automatic Closure Interlock (AC) (TAC No. MC3799)"

(2CNA030507)

2. 10 CFR Part 50, Appendix A, General Design Criteria 55, Reactor Coolant Pressure Boundary Penetrating Containment

3. 10 CFR 50.2, Definitions, Reactor Coolant Pressure Boundary

4. ANO-2 Safety Analysis Report

5. NUREG 1432, Revision 3, Standard Technical Specifications Combustion Engineering Plants, Surveillance Requirement 3.4.14.2, Page 3.4.14-4

6. Branch Technical Position RSB 5-1, Design Requirements of the Residual Heat Removal System