ML20137C854
| ML20137C854 | |
| Person / Time | |
|---|---|
| Site: | North Anna  |
| Issue date: | 03/18/1997 |
| From: | Ohanlon J VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML20137C857 | List: |
| References | |
| RTR-REGGD-01.045, RTR-REGGD-1.045 97-102, GL-84-04, GL-84-4, NUDOCS 9703250148 | |
| Download: ML20137C854 (9) | |
Text
-
4 4
WmNIA Eu:cTHIC ANI) POWER Com%NY Ricmioso, VHu;INI A 2M61 March 18, 1997 Document Control Desk Serial No.97-102 United States Nuclear Regulatory Commission NAPS /ETS/GSS Washington, D. C. 20555 Docket Nos. 50-338 50-339 License Nos. NPF-4 NPF-7 Gentlemen:
VIRGINIA ELECTRIC AND POWER COMPANY N_QRTH ANNA POWER STATION UNITS 1 AND 2 CONTAINMENT GASEOUS AND PARTICULATE RADIATION MONITORS The Containment Gaseous and Particulate Radiation Monitors are one of several methods required by Technical Specifications to monitor reactor coolant system
~
pressure boundary integrity. Regulatory Guide (RG) 1.45, " Reactor Coolant Pressure Boundary Leakage Detection System," dated May 1973, establishes design and operating requirements for leakage detection systems. The Bases for North Anna Technical Specification 3/4.4.6.1 " Leakage Detection Systems," states that the RCS leakage detection systems are generally consistent with Regulatory Guide 1.45. Based on our current operating practices, seismic qualification of the Containment Gaseous and Particulate Radiation Monitoring System is not necessary to meet the functional intent of RG 1.45 or Technical Specification 3/4.4.6.1. This Technical Specifications Bases change will modify our commitment on how we meet the intent of RG 1.45 to monitor the reactor coolant system pressure boundary for leakage during normal operations and after a seismic event in order to provide the operator with information to determine whether to shutdown the unit. We are providing the following Technical Specifications Bases change for your review.
In addition to the Technical Specifications Bases change, we will also change the UFSAR consistent with our change in commitment.
This change will clarify the operation of the Containment Gaseous and Particulate Radiation Monitor System after a seismic event. Specifically, for plant operation after a seismic event, the Containment Gaseous and Particulate Radiation Monitoring System must remain operable or the affected unit (s) will be placed in Cold Shutdown. This is a change to the original licensing basis commitment that specified that the containment gas and particulate monitors would be designed to operate following a seismic event.
A discussion of the Technical Specifications Bases change is provided in Attachment 1.
The Technical Specifications Bases changes are provided for both units in Attachment
- 2. It has been determined that the proposed Technical Specifications changes do not involve an unreviewed safety question as defined in 10 CFR 50.59. The Technical ju "M Mini appaipppppps I
i
)
Specifications Bases change has been reviewed and approved by the Station Nuclear Safety and Operating Committees and the Management Safety Review Committee.
If you have any questions regarding these commitments, please contact us.
Very truly yours, James P. O'Hanlon Senior Vice President - Nuclear Attachments Commitments in this letter:
1.
Are summarized in Attachment 3 to this letter, cc:
U. S. Nuclear Regulatory Commission l
Region ll 101 Marietta Street, N. W.
Suite 2900 Atlanta, Georgia 30323 NRC Senior Resident inspector North Anna Power Station 1
d Discussion of Change i
i f
North Anna Power Station Units 1 and 2 Virginia Electric and Power Company i
t
?
I
1 1
Discussion of Change Introduction The Containment Gaseous and Particulate Radiation Monitoring System is one of the methods required by Technical Specifications to monitor reactor coolant system pressure boundary integrity during normal plant operations and after a seismic event.
Regulatory Guide (RG) 1.45, " Reactor Coolant Pressure Boundary Leakage Detection System," dated May 1973 establishes design and operating requirements for leakage detection systems.
The bases for North Anna Technical Specification 3/4.4.6.1
" Leakage Detection Systems," states that the RCS leakage detection systems are generally consistent with Regulatory Guide 1.45.
Based on our current operating practices, the seismic qualification requirements for the Containment Gaseous and Particulate Radiation Monitoring System can be eliminated and still meet the intent of
{
RG 1.45 in support of the requirements of Technical Specification 3/4.4.6.1. Therefore, we are providing the following Technical Specification Bases change for your review.
This Bases change will clarify how we meet the intent of RG 1.45 to monitor the reactor coolant system pressure boundary for leakage during normal operations and after a seismic event.
The safety function provided by these radiation monitors is maintained by requiring that the operability of the Containment Gaseous and Particulate Radiation Monitoring System be verified immediately after a seismic event. To continue plant operation, these systems must remain operable or the affected unit (s) will be shut down and coolod down to Cold Shutdown. The functional ability to monitor the reactor coolant pressure boundary for minor leakage in order to take appropriate corrective action is therefore maintained by this Technical Specification Bases change. Therefore, an unreviewed safety question is not created by this Bases change.
This basis change is actually more conservative than existing Technical Specification requirements. The existing Specifications permit continued operation with inoperable radiation monitors for 30 days while relying on the other leakage detection system, whereas the modified Basis commits to immediate actions following a seismic event to verify continued operability or initiate a plant shutdown.
Background
RG 1.45 states that "the leakage detection systems should be capable of peiforming their function following seismic events that do not require plant shutdowns.
The airbome particulate radioactivity monitoring system should remain functional when subjected to the SSE." The bases of Technical Specification 3/4.4.6.1 " Leakage Detection Systems," states that the RCS leakage detection systems are generally consistent with RG 1.45.
The Containment Gaseous and Particulate Radiation Monitoring System is one of the leakage detection systems required by Technical Specification 3/4.4.6.1.
Current operating practices for a seismic event, as directed by abnormal procedures, require an immediate determination of the continuing operability of the Containment Gaseous and Particulate Radiation Monitoring System, and if the monitoring system is not operable the operator is directed to shutdown the affected unit (s) and cool the unit (s) to Cold Shutdown. These actions are consistent with the intent of Regulatory Guide 1.45 to have an operable leakage detection system to monitor the reactor coolant system pressure boundary following seismic events that do not require plant shutdowns and to permit early detection of a degraded condition in the reactor coolant system pressure boundary with the plant operating. Based on these current procedural requirements for verification of operability following a seismic event and the existing diverse leakage detection available (e.g., sump monitoring and reactor coolant system makeup rate) seismic qualification of containment gaseous and particulate radiation monitor systems is not necessary to meet the intent of RG 1.45.
These same monitors are also used to initiate containment purge and exhaust isolation during a fuel handling accident. However, the fuel handling accident in containment has been analyzed assuming the failure of radiation monitor system during refueling.
The offsite and control room doses have been evaluated and approved by the NRC as discussed in the Safety Evaluation Report for North Anna Technical Specifications Amendments Nos.198 and 179 for Units 1 and 2, dated February 2,1996.
Therefore, we are changing our commitment to provide seismically a qualified Containment Gaseous and Particulate Radiation Monitoring System to detect reactor coolant system boundary leakage after a seismic event. In place of the seismically qualified radiation monitor system, a procedural requirement has been established to immediately verify containment radiation monitor system operability after a seismic event to continue operation. If the containment radiation monitoring system cannot be verified as operable, then the affected units will be shutdown and cooled down as appropriate.
Licensing Basis UFSAR Section 5.2.4.1.1 states that the RCS leakage systems, of which the Containment Gaseous and Particulate Radiation Monitoring System is defined as one of multiple indications, will be functional following a seismic event. Section 3A.45 of the UFSAR states that compliance with RG 1.45 is discussed in Section 5.2.4.1.
The Technical Specification Bases for TS 3/4.4.6.1, " Leakage Detection Systems," states that the RCS leakage detection systems are " generally consistent" with RG 1.45. Table
- 3. 2-1 of the UFSAR indicates the process radiation monitoring system, containment gaseous and particulate monitor should be seismic category 1.
Generic Letter 84-04, Safety Evaluation of Westinghouse Topical Reports Dealing with Elimination of Postulated Pipe Breaks in PWR Primary Main Loops, dated February 1, 1984 permitted the elimination of the asymmetric blowdown loads resulting for double i
ended pipe breaks in the main coolant loop piping from the design basis of
Westinghouse Owner's Group plants with two conditions.
The second condition required leakage detection systems at the facility sufficient to provide adequate margin to detect the leakage from a postulated circumferential throughwall flaw utilizing the guidance of RG 1.45 with the exception that seismic qualification of the airbome particulate radiation monitor was not necessary. Based on the NRC's generic Safety Evaluation Report for Elimination of Postulated Pipe Breaks in PWR Primary Main Loops and the North Anna specific Safety Evaluation Report (amendment numbers 107 for Unit 1 and 93 for Unit 2 dated December 5,1988), it is no longer necessary to have the containment airbome particulate radiation monitor seismically qualified for the detection of reactor coolant system pressure boundary leakage after a safe shutdown earthquake.
The Containment Gaseous and Particulate Radiation Monitoring System is required to be operable in Mode 6 (TS 3.3.3.1) for containment purge and exhaust isolation and in Modes 1 through 4 (TS 3.4.6.1) for reactor coolant system pressure boundary leakage i
detection. If one of the radiation monitors associated with the RCS leakage detection function in modes 1 through 4 is inoperable, then Tech Spec 3.4.6.1 applies. This requires that RCS leakage calculations be performed every 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> for a maximum of 30 days, otherwise be in Hot Standby within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />, and Cold Shutdown within the j
following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />. If the Containment Gaseous and Particulate Radiation Monitoring System is inoperable in Mode 6, the action statement of Tech Spec 3.9.9 applies for Containment Purge and Exhaust isolation.
This requires the purge and exhaust penetration to be isolated for refueling operations to continue uninterrupted. The bases section states that the automatic isolation of purge and exhaust on high radiation levels i
restricts the release of radioactive material from the containment atmosphere to the j
environment. The fuel handling accident in containment has been analyzed assuming the failure of radiation monitors during refueling. The offsite and control room doses have been evaluated and approved by the NRC as discussed in the Safety Evaluation Report for North Anna Technical Specifications Amendments Nos.198 and 179 for Units 1 and 2, dated February 2,1996.
Specific Chances The current basis for TS 3/4.4.6 states:
The RCS leakage detection systems required by this specification are provided to monitor and detect leakage from reactor coolant pressure boundary. These detection systems are generally consistent with the recommendations of Regulatory Guide 1.45, " Reactor Coolant Pressure boundary leakage Detection Systems," May 1973.
The revised basis provides clarification of how the intent of RG 1.45 is met and reads as follows:
The RCS leakage detection systems required by this specification are provided4e monitor and detect leakage from the reactor coolant pressure
boundary during normal plant operations and after seismic events to provide prompt and quantitative information to the operators to permit immediate corrective actions should the reactor coolant pressure boundary leak be detrimental to the safety of the facility.
These detection systems are generally consistent with the recommendations of Regulatory Guide 1.45, " Reactor Coolant Pressure Boundary Leakage Detection Systems," May 1973. The containment atmospheric particulate and gaseous radioactivity monitoring system is not fully seismically qualified. Consistent with RG 1.45 these monitors can perform their intended function during normal plant operations. To ensure the safety function of detecting reactor coolant pressure boundary leakage is maintained after a seismic event the operability of these monitors is required to be verified immediately following a seismic event or the affected unit (s) will be shut down and cooled down to Cold Shutdown.
Safety Sianificance This basis change is actually more conservative than existing Technical Specification requirements in that the existing Specifications permit continued operation for 30 days while relying on the other leakage detection system whereas the modified basis commits to immediate action following a seismic event.
The radiation monitors are non-safety related and the original design classification is not changed. The radiation monitors provide indication only during Modes 1 through 4 and have no effect on accident precursors.
Thus the elimination of the seismic qualification requirements for the Containment Gaseous and Particulate Radiation Monitoring System does not increase the probability of previously analyzed accidents.
The required actions of the Abnormal Procedure (AP) maintain the safety function, 4
since the radiation monitors will either be verified operable following the seismic event, or not relied upon if they are determined to be inoperable. Furthermore, if the radiation monitors are determined to be inoperable, the affected unit (s) will be shut down and cooled down to Cold Shutdown assuming that a reactor coolant system pressure boundary leak cannot be detected. Therefore, the consequences of any previously analyzed accidents during Modes 1 through 4 are not increased.
During mode 6 the radiation monitors isolate containment purge and exhaust. The fuel handling accident in containment has been analyzed assuming the failure of radiation monitors during refueling. The offsite and control room doses have been evaluated and approved by the NRC as discussed in the Safety Evaluation Report for North Anna Technical Specifications Amendments Nos.198 and 179 for Units 1 and 2, dated February 2,1996. Therefore, the consequences of an accident or malfunction of equipment previously analyze during Mode 6 are not increased.
The Abnormal Procedure (AP) ensures that the probability of occurrence of a malfunction of equipment important to safety does not increase. The safety function of these monitors is to detect leakage from the reactor coolant pressure boundary during normal plant operations and after seismic events to provide prompt and quantitative information to the operators to permit immediate corrective actions should reactor coolant pressure boundary leakage be detrimental to the safety of the facility.
Therefore, malfunction of equipment previously analyzed is not increased.
Operation of the unit with portions of the radiation monitoring system non-seismically qualified does not affect the ability of the radiation monitors to sample the containment atmosphere. The radiation monitors only serve a monitoring function during plant operations and are not part of any system or component that could be an accident initiator. Therefore, the possibility of an accident or malfunction of equipment not previously analyzed is not increased.
The safety function of the RCS leakage detection systems is to provide prompt and quantitative information to the operators to permit immediate corrective actions should the reactor coolant pressure boundary leakage be detrimental to the safety of the facility. The safety function is maintained during normal plant operations and after seismic events by procedurally requiring verification of the proper operation of the radiation monitoring for continued operation or shutting down the affected units assuming a flaw in the reactor coolant system. The Technical Specifications Limiting Conditions for Operation continue to be met. Therefore, the margin of safety as described in the bases of the Technical Specifications is not increased.
Based on the above discussion an Unreviewed Safety Question does not exist as a result of the changes in the seismic qualification for the Containment Gaseous and Particulate Radiation Monitoring System.
1 i
1 i
j j
Basis Change i
i 2
)
5 North Anna Power Station Units 1 and 2 Virginia Electric and Power Company l