ML090920316
| ML090920316 | |
| Person / Time | |
|---|---|
| Site: | North Anna  |
| Issue date: | 03/27/2009 |
| From: | Stoddard D Virginia Electric & Power Co (VEPCO) |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| Download: ML090920316 (12) | |
Text
VIRGINIA ELECTRIC AND POWER COMPANY RICHMOND, VIRGINIA 23261 March 27, 2009 United States Nuclear Regulatory Commission Serial No.09-152 Attention: Document Control Desk NAPS/JHL Washington, D. C. 20555 Docket Nos. 50-338 50-339 License Nos. NPF-4 NPF-7 Gentlemen:
VIRGINIA ELECTRIC AND POWER COMPANY (DOMINION)
NORTH ANNA POWER STATION UNITS 1 AND 2
SUMMARY
OF FACILITY CHANGES, TESTS AND EXPERIMENTS Pursuant to 10 CFR 50.59(d)(2), enclosed is a summary description of Facility Changes, Tests and Experiments identified in Regulatory Evaluations implemented at the North Anna Power Station during 2008. Also, enclosed is a Commitment Change Evaluation Summary that was completed.
If you have any questions, please contact Page Kemp at (540) 894-2295.
Sincerely, Daniel G. Stoddard, P.E.
Site Vice President Attachment cc: U. S. Nuclear Regulatory Commission Region II Atlanta Federal Center 61 Forsyth St., SW, Suite 23T85 Atlanta, Georgia 30303 NRC Senior Resident Inspector North Anna Power Station
- ýLL-C47
ATTACHMENT 1 10 CFR 50.59
SUMMARY
DESCRIPTION OF FACILITY CHANGES. TESTS AND EXPERIMENTS NORTH ANNA POWER STATION UNITS I AND 2 VIRGINIA ELECTRIC AND POWER COMPANY (DOMINION)
NORTH ANNA UNITS 1 & 2 10 CFR 50.59
SUMMARY
DESCRIPTION OF FACILITY CHANGES, TESTS AND EXPERIMENTS REGULATORY EVALUATION: 08-SE-ST-01, Revision 1 (Revision 0 was revised prior to performance of the special test)
Document Evaluated: Special Test 0-ST-FP-002, Revision 1 - Low Pressure C02 Blower Door Test Brief
Description:
The activity consists of a blower door test in accordance with NFPA 2001, 12A and ASTM E779, Standard Test Method for Determining Air Leakage Rate by Fan Pressurization.
Reason for Change: The test is being performed to determine if an overpressure condition may exist within the rooms on a fire protection 002 system discharge.
Summary: The activity consists of a blower door test in accordance with NFPA 2001, 12A and ASTM E779, Standard Test Method for Determining Air Leakage Rate by Fan Pressurization. Areas or rooms to be tested consist of the Units 1 and 2 Cable Spreading Rooms and Unit 2 Normal (307) Switchgear Room. The test is conducted by installing a fan in a doorway to the area being tested. The fan is used to develop both a positive and negative pressure in the tested area. Leakage is determined through calculation using pressure and flow readings at the fan. Revision 1 to 0-ST-FP-002 revises the methodology for addressing the Control Pressure Boundary impact.
Technical Specifications for the Control Room pressure boundary will not be entered since a breach does not occur. The door fan is under administrative control and can be shutdown immediately if required due to a design basis accident.
The test is being performed to determine if an overpressure condition may exist within the rooms on a fire protection 002 system discharge. Fan speed is adjusted to obtain a pressure between the test room and the volume surrounding the room, equivalent to approximately 10 to 60 Pa or 0.04" to 0.24" of water column. This pressure is similar to the steady state pressure exerted by the 002 at floor level at the start of its retention period. The maximum of 60 Pa does not pose any threat to the integrity of the walls, seals, or doors.
Special Test Results: Unit 2 Normal Switchgear Room and Cable Tray Spreading Room successfully passed the blower test with estimated room leakage of 704 in and 350 in2, respectively. The Unit 1 Cable Tray Spreading Room had estimated room leakage of 200 in12 which was less than the minimum required by NFPA 12 for light and normal construction. As a result, compensatory measures were initiated due to the potential for an over pressure condition on a 002 discharge. Design Change N-08-157 installed a pressure relief vent in the room to ensure adequate venting is achieved on a 002 discharge.
REGULATORY EVALUATION: 08-SE-OT-02 Document Evaluated: Engineering Transmittal (ET) NAF-08-0061, Implementation of Revised Safety Analysis Limit for High Pressurizer Pressure Reactor Trip, North Anna Units 1 and 2 Brief
Description:
The activity implements a change to the high pressurizer pressure reactor trip Safety Analysis Limit (SAL) and revision to the North Anna UFSAR safety analyses that credit the limit.
Reason for Change: The high pressurizer pressure SAL was increased to support the use of Method 1 and 2 as detailed in Part II of ISA Standard S67.04.
Summary: The change involves revising the North Anna UFSAR safety analysis with an increase in the high pressurizer pressure Safety Analysis Limit (SAL) from 2396 psia to 2406 psia. The Loss of External Electrical Load (LOL) accident was reanalyzed for this increase in Engineering Calculation SM-1259, Revision 0, Addendum B. The remaining UFSAR safety analyses that credit high pressurizer pressure are evaluated in Engineering Transmittal ET-NAF-08-0061, Revision 0. The UFSAR Chapter 15 safety analyses can accommodate an increase in the Pressurizer Pressure - High SAL to 2406 psia and still meet the applicable acceptance criteria. The increased high pressurizer pressure SAL creates additional margin from the Technical Specifications allowable yalue (TS 3.3.1 < 2370 psig) and supports the future use of Methods 1 and 2 as detailed in Part II of ISA Standard S67.04 for applying the Channel Statistical Allowance (CSA).
REGULATORY EVALUATION: 08-SE-MOD-01 Document Evaluated: North Anna Unit 1, Design Change Package (DCP)05-013, Field Change (FC) 2, NRC GSI-191 Containment Sump Strainer Designer Brief
Description:
The activity completes the design and licensing basis requirements associated with the Generic Safety Issue (GSI) 191 containment sump strainer design modification.
Reason for Change: The purpose of FC 2 to DCP 05-013 is to document the results of the chemical effects analysis, chemical effects testing, downstream effects analysis (wear and fuels) and updates the configuration to meet all requirements of GSI-1 91.
The strainers comply with the GSI-1 91 design and licensing bases.
Summary: GSI-191 and Generic Letter (GL) 2004-02 requests that all license holders of operating PWRs evaluate the operation of the Emergency Core Cooling System (ECCS) and Recirculation Spray System (RSS) to ensure that post-accident debris blockage will not impede or prevent the operation of the systems in the recirculation
mode during Loss of Coolant Accident (LOCA) or other High Energy Line Break (HELB) accidents for which sump recirculation is required.
In response to the NRC request, the existing containment sump screen has been evaluated and determined to be unsatisfactory. This DCP replaces the existing containment sump screen with a new strainer to address the concerns stated in GSI-191.
Other modifications to support the installation and operation of the new containment sump strainer include:
" Modification to the Quench Spray (QS) bleed line to the suction of the Inside Recirculation Spray (IRS) pumps to prevent air ingestion into the pump.
- Modifications to the sump level instrumentation to prevent blockage of the floating elements due to debris.
" Revision of the acceptable sump pH upper limit from 9.5 to 8.5.
Replacement of the existing containment sump screens with the new strainers and modification to other plant equipment to support the new strainers operation cannot initiate an accident or result in an increase in the occurrence of a malfunction of any structures, systems or components (SSCs) important to safety previously evaluated in the UFSAR.
The proposed design change does not adversely affect the ECCS and RSS, or introduce any radiological sources, processes or materials and thus does not increase the radiological doses to the public and control room operators. Therefore, the dose consequences of an accident and due to malfunction of SSC previously evaluated in the UFSAR-remain unchanged.
Installation of the passive strainers, modification of the QS bleed lines, and physical
.modification to the level transmitters does not create an accident or malfunction of a SSC that is different than previously evaluated in the UFSAR.
The effects of the additional steel in the containment on the Framatome ANP Advanced Mark-BW Fuel Peak Cladding Temperature (PCT) analysis have been evaluated and determined that it has no adverse impact on the PCT.
In response to the NRC request via GL 2004-02 and GSI-191, the existing containment sump screens have been evaluated and determined to be unsatisfactory based on the new methodology outlined in NEI 04-07 and its associated SER.
Various evaluations and testing have been performed in accordance with the NRC approved methodology (generic basis) and guidance provided in NEI 04-07 and its associated SER to ensure that the strainers design basis complies with the NRC and other industry requirements and will perform their intended safety function after an accident.
The guidance/requirements provided in the new methodology to determine the strainer design basis is more stringent than previously provided by the NRC. This resulted in a more conservative strainer design than the existing screen design. Therefore, this activity may be implemented without prior NRC approval. This evaluation is performed to document the acceptability of the method for North Anna Power Station.
The original design basis function of the containment sump level transmitters has not been altered by the proposed activity. Only physical modifications have been made to the transmitters to prevent possible clogging of the float due to debris after an accident.
All previous evaluations remain unchanged and no prior NRC approval is required for this activity.
Modification of the QS bleed line to the IRS pump suction ensures the out of service QS and IRS pumps will have no adverse effect due to air ingestion. The required QS bleed line flow is maintained during operation in accident conditions. DCP 05-014 has determined that there is no adverse effect on the system. No prior NRC approval is required for this activity.
REGULATORY EVALUATION: 08-SE-MOD-02 Document Evaluated: North Anna Unit 2, Design Change Package (DCP)05-014, Field Change (FC) 3, NRC GSI-191 Containment Sump Strainer Design Brief
Description:
The activity completes the design and licensing basis requirements associated with the Generic Safety Issue (GSI) 191 containment sump strainer design modification.
Reason for Change: The purpose of FC 3 to DCP 05-014 is to document the results of the chemical effects analysis, chemical effects testing, downstream effects analysis (wear and fuels) and updates the configuration to meet all requirements of GSI-191.
The strainers comply with the GSI-1 91 design and licensing bases.
Summary: GSI-1 91 and Generic Letter (GL) 2004-02 requests that all license holders of operating PWRs evaluate the operation of the Emergency'Core Cooling System (ECCS) and Recirculation Spray System (RSS) to ensure that post-accident debris blockagewill not impede or prevent the operation of the systems in the recirculation mode during Loss of Coolant Accident (LOCA) or other High Energy Line Break (HELB) accidents for which sump recirculation is required.
In response to the NRC request, the existing containment sump screen has been evaluated and determined to be unsatisfactory. This DCP replaces the existing containment sump screen with a new strainer to address the concerns stated in GSI-191.
Other modifications to support the installation and operation of the new containment sump strainer include:
Modification to the Quench Spray (QS) bleed line to the suction of the Inside Recirculation Spray (IRS) pumps to prevent air ingestion into the pump.
Modifications to the sump level instrumentation to prevent blockage of the floating elements due to debris.
Revision of the acceptable sump pH upper limit from 9.5 to 8.5.
Replacement of the existing containment sump screens with the new strainers and modification to other plant equipment to support the new strainers operation cannot initiate an accident or result in an increase in the occurrence of a malfunction of any structures, systems or components (SSCs) important to safety previously evaluated in the UFSAR.
The proposed design change does not adversely affect the ECCS and RSS, or introduce any radiological sources, processes or materials and thus does not increase the radiological doses to the public and control room operators. Therefore, the dose consequences of an accident and due to malfunction of SSC previously evaluated in the UFSAR remain unchanged.
Installation of the passive strainers, modification of the QS bleed lines, and physical modification to the level transmitters does not create an accident or malfunction of a SSC that is different than previously evaluated in the UFSAR.
The effects of the additional steel in the containment on the Framatome ANP Advanced Mark-BW Fuel Peak Cladding Temperature (PCT) analysis have been evaluated and determined that it has no adverse impact on the PCT.
In response to the NRC request via GL 2004-02 and GSI-191, the existing containment sump screens have been evaluated and determined to be unsatisfactory based on the new methodology outlined in NEI 04-07 and its associated SER.
Various evaluations and testing have been performed in accordance with the NRC approved methodology (generic basis) and guidance provided in NEI 04-07 and its associated SER to ensure that the strainers design basis complies with the NRC and other industry requirements and will perform their intended safety function after an accident.
The guidance/requirements provided in the new methodology to determine the strainer design basis is more stringent than previously provided by the NRC. This resulted in a more conservative strainer design than the existing screen design. Therefore, this activity may be implemented without prior NRC approval. This evaluation is performed to document the acceptability of the method for North Anna Power Station.
The original design basis function of the containment sump level transmitters has not been altered by the proposed activity. Only physical modifications have been made to the transmitters to prevent possible clogging of the float due to debris after an accident.
All previous evaluations remain unchanged and no prior NRC approval is required for this activity.
Modification of the QS bleed line to the IRS pump suction ensures the out of service QS and IRS pumps will have no adverse effect due to air ingestion. The required QS bleed line flow is maintained during operation in accident conditions. DCP 05-014 has determined that there is no adverse effect on the system. No prior NRC approval is required for this activity.
ATTACHMENT 2 COMMITMENT CHANGE EVALUATION
SUMMARY
NORTH ANNA POWER STATION UNITS 1 AND 2 VIRGINIA ELECTRIC AND POWER COMPANY (DOMINION)
Commitment Change Evaluation Summary Original Commitment
Description:
On March 29, 1985, Virginia Electric and Power Company requested license amendments, in the form of Technical Specification changes, to the Operating Licenses for North Anna Units 1 and 2. The changes were to extend the allowed outage time for the Service Water System, from 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> to 168 hours0.00194 days <br />0.0467 hours <br />2.777778e-4 weeks <br />6.3924e-5 months <br />, for planned modifications and maintenance activities. Virginia Electric and Power Company (Dominion) letter to the NRC dated August 22, 1985 (Serial No.85-521) documented the results of a meeting regarding mechanical cleaning of the service water piping and valve repairs. This letter discussed the levels of defense against accidental opening of cross-tie valves and other contingency actions. Defense in' depth actions developed in 1985 included:
- Manual boundary valves are tagged closed and then verified closed by a second individual.
- Motor-operated boundary valves are closed, tagged, verified by a second individual, and power removed from the motor circuit.
- Boundary valves greater than or equal to 18 inches are chained and locked in the closed position Contingency actions developed in the unlikely event the defense in depth actions are circumvented included:
- Developing an abnormal procedure to mitigate the postulated flooding.
- A station security officer will be stationed in the Service Water Pumphouse to insure the cross-tie valves are not tampered with.
- A valve watch operator will be stationed in the Auxiliary Building basement to manually operate valves, if needed, in the CC Heat Exchanger area, except for two supply valves which can be remotely operated from the control room.
- Partially sealing the charging pump cubicles to the 44 inch level to prevent flooding of the charging pumps.
Based on the above contingency actions and calculated flooding rates, it was determined that the operator has in excess of ten minutes to complete actions to mitigate flooding due to a'postulated opening of a boundary valve in excess of 18 inches in diameter. Operator action from the Auxiliary Building or Control Room as applicable can readily be accomplished in ten minutes, thereby preventing flooding of the charging pump cubicles.
On October 25, 1985, the NRC issued License Amendments 70 and 56 to revise the allowable time that one of the redundant service water headers can be inoperable from 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> to 168 hours0.00194 days <br />0.0467 hours <br />2.777778e-4 weeks <br />6.3924e-5 months <br /> provided 3 out of 4 service water pumps and 1 out of 2 auxiliary service water pumps are operable during the 168 hour0.00194 days <br />0.0467 hours <br />2.777778e-4 weeks <br />6.3924e-5 months <br /> Action Statement.
The Safety Evaluation Report attached to the License Amendments documents the NRC Staff evaluation of the change. The NRC staff examined the potential for adverse effects that the mechanical cleaning program could have on plant
operations beyond those examined by the licensee. The staff examined the potential for adverse effects from the flooding of essential areas and equipment through the open service water train (due to accidental connection with the intact train). The procedures and steps to be taken by the licensee to prevent and, if necessary, mitigate the effects of flooding during the mechanical cleaning program include the following:
The license will utilize administrative controls such as "tag out" procedures, locking closed those valves (in lines greater than 18 inches in diameter) that could connect the open service Water train with the operating train. Also, constant on-location surveillance by plant personnel will minimize the possibility of a flood occurring.
- The charging pump cubicles will be sealed to the 44 inch level to provide the operators with ample time to isolate the open line before the charging pumps are flooded. The flow through the open train can be terminated by using a blind flange that can be slid over the open end, by re-closing the valve inter-connecting the two service water trains (if inadvertently opened), or by stopping the service water pumps.
- Certain MOVs and pumps in, systems used to bring the plant to a cold shutdown state could be damaged by the postulated flood. Analyses and procedures provided by the licensee show that the necessary cold shutdown equipment could be restored to service within approximately two days.
It should be noted that Virginia Electric and Power Company letter dated October 26, 1995 (Serial No.95-556), changed the commitment for posting a Security Officer at the Service Water Pumphouse during service water modification and maintenance activities.
Revised Commitment
Description:
The contingency action is being revised for providing constant on-location surveillance by plant personnel to minimize the 15ossibility of a flood occurring during maintenance activities when entering the 168 hour0.00194 days <br />0.0467 hours <br />2.777778e-4 weeks <br />6.3924e-5 months <br /> Action Statement. The revised contingency action is to have an employee in the Auxiliary Building basement during disassembly of service water system components in the Auxiliary Building that are in excess of 18 inches in diameter. After disassembly activities are complete, Auxiliary Building sump alarms in the control room will alert personnel of postulated boundary valve leakage. Personnel will still be able to complete actions to mitigate flooding of the charging pump cubicles due to inadvertent opening of a boundary valve in excess of 18 inches in diameter.
Justification for the Commitment Change: The revised contingency action to have an employee in the Auxiliary Building basement only during disassembly of service water system components in the Auxiliary Building that are in excess of 18 inches in diameter is justified. After disassembly activities are complete, potential boundary valve leakage into the Auxiliary Building sump would be identified by annunciator alarms in
the Control Room. The Auxiliary Building sump level indicator is also available on the Unit 1 and 2 control boards. Operations personnel would initiate actions to mitigate a potential leakage concern based on annunciator alarms and or control board level indications. The Auxiliary Building sump annunciator alarms and sump level indicator must be operable to implement the revised contingency action. These controls are considered adequate and equivalent to the original commitment.
A review of applicable Operating Procedures, Abnormal Procedures, Annunciator Response (AR) Procedures, UFSAR Chapter 9 and System Design Basis Document for Primary Vents and Drains Systems was performed. The Auxiliary Building has been provided with a sump to collect leakage. The leakage is transferred by sump pumps to either the high or low level Liquid Waste System. There are two sump pumps with 50 gpm capacity. The Auxiliary Building sump pumps are duplex arrangements. The sump pumps are controlled by float switches that cycle them on and off. Alternators provide equal wear on duplex pumps. Two additional float switches are provided to 1) start the standby pump in the event the operating pump fails and 2) sound an alarm in the main control room on high sump level. The sump pumps may also be operated manually. When the Auxiliary Building sump reaches the 48" level, an annunciator alarms (1-AR-E-F6) in the Control Room. Reflash of the annunciator alarm occurs at the 50" level. Control room operators would respond to Auxiliary Building sump annunicator alarms and complete actions (in accordance with 0-AP-39.2, Auxiliary Building Flooding or 0-MOP-49.11, Service Water Flooding in Auxiliary Building) to mitigate potential flooding. Operators would be able to respond in a timeframe that would prevent flooding of the charging pump cubicles.