ML13309A355
| ML13309A355 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 10/27/1992 |
| From: | Krieger R SOUTHERN CALIFORNIA EDISON CO. |
| To: | Martin J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| References | |
| NUDOCS 9211130175 | |
| Download: ML13309A355 (5) | |
Text
Southern California Edison Company SAN ONOFRE NUCLEAR GENERATING STATION P. O. BOX 128 SAN CLEMENTE, CALIFORNIA 92674-0128 R. W. KRIEGER TELEPHONE STATION MANAGER October 27, 1992 (714) 368-6255 Mr. John B. Martin Regional Administrator U. S. Nuclear Regulatory Commission, Region V 1450 Maria Lane, Suite 210 Walnut Creek, California 94596
Subject:
Docket No. 50-206 Request for Temporary Waiver of Compliance Inservice Testing - Safety Injection System San Onofre Nuclear Generating Station, Unit 1 The purpose of this letter is to request a Temporary Waiver of Compliance from the requirements of Technical Specification (TS) 4.7, "Inservice Inspection Requirements," for a period of approximately one month. Approval of this request would allow an extension of the surveillance interval for Pump Relief Request (PRR) No. 3, "Safety Injection Recirculation Pump - Alternate Testing."
This PRR states that the recirculation pumps shall be tested wet "every refueling or once every 2 years."
The two year intervals for recirculation pumps G45A and G45B expire on October 28 and October 31, 1992, respectively. Approval of this temporary waiver of compliance is requested for a period not to exceed 40 days commencing on October 28, 1992;.until Unit 1 enters Mode 5, which is expected to occur on or about December 1, 1992.
This approval will avoid an unnecessary plant shutdown prior to the permanent Unit 1 shutdown scheduled for November 30, 1992.
A.
Requirements For Which The Waiver Is Requested:
Applicable TS/ASME Requirements:
TS 3.3.1, "Safety Injection System and Containment Spray Systems - Operating, Status," defines the operability requirements for the Safety Injection (SI),
Recirculation, and Containment Spray Systems. The objective of this TS is to ensure availability of the Emergency Core Cooling System, (ECCS) subsystems.
This TS requires that the recirculation pumps be operable during Modes 1 through 4. Under the most restrictive condition, with both pumps inoperable, one pump shall be restored to operable status within one hour or the plant shall be placed in Cold Shutdown (Mode 5) within the next 20 hours2.314815e-4 days <br />0.00556 hours <br />3.306878e-5 weeks <br />7.61e-6 months <br />.
9211130175 921027 PDR ADOCK 05000206 G
John B. Martin 2 -
October 27, 1992 TS 3.0.3 requires, in part, that when a limiting condition for operation is not met, except pursuant to associated ACTION requirements, unit shutdown shall be initiated within one hour.
TS 4.0.3 states that the failure to comply with the requirements of TS 4.0.2 constitutes noncompliance with the operability requirements for a TS Limiting Condition for Operation (LCO).
TS 4.2.1, "Safety Injection and Containment Spray System Periodic Testing,"
Section II.A.(2)(3) requires that the recirculation pumps are to be run dry each month with proper starting verified by observing running current.
TS 4.7 requires that inservice inspection of ASME Code Class 1, 2, and 3 components be performed in accordance with Section XI of the ASME Boiler and Pressure Vessel Code and applicable Addenda as required by 10 CFR 50, Section 50.55a(g).
SCE considers.this TS to apply to inservice testing (IST) as well as inservice inspection (ISI).
Performance of these inspections, via the Inservice Testing (IST) Program, are intended to ensure the operational readiness of certain safety related pumps and valves throughout the plant life.
ASME Section XI, Article IWP-3000 requires obtaining pump hydraulic measurements on a periodic basis while at power. Since these pumps are located in the containment sump, which is a high radiation area and not accessible during operation, it was not possible to take vibration and bearing temperature data while operating and submerged. As a result, PRR No. 3 was initially submitted to the NRC for approval along with the original IST program submittal dated January 24, 1984, Letter from M. 0. Medford (SCE) to D. M. Crutchfield (NRC), "Docket 50-206, In-Service Test Program for Pumps and Valves, SONGS Unit 1."
PRR No. 3 requires that "every refueling or once every two years" the containment sump is to be filled with water and the recirculation pumps are to be run at shut-off head. No vibration or bearing temperature data is obtained due to the pumps being submerged. This testing combined with the monthly dry testing specified in TS 4.2.1 was considered the approved alternate testing in lieu of the required ASME Section XI, testing requirements.
(NOTE: This PRR pre-dates the April 3, 1989, Generic Letter 89 04, "Guidance on Developing Acceptable Inservice Testing Programs," and was therefore approved under the rules of the generic letter. PRR No. 3 was subsequently approved by an NRC safety report for the second 10 year IST interval per a Letter from Charles.M. Tramell (NRC) to Kenneth P. Baskin (SCE), "Inservice Testing Safety Evaluation (TAC Nos. 11231 and 67107),
SONGS 1," dated June 9, 1989.)
SI System Design:
The Unit 1 Safety Injection System (SIS) is designed, in part, to mitigate core damage resulting from overheating following a loss of coolant accident (LOCA).
Initially after a LOCA, the SIS injects borated water from the Refueling Water Storage Tank (RWST) through the SIS header and into the three Reactor Coolant System (RCS) loopsvia separate SIS lines.
John B. Martin 3 -
October 27, 1992 Following depletion of the RWST, the Recirculation System (RS) provides core cooling for extended periods following design basis accidents and is initiated after a sufficient quantity of water has accumulated in the containment sump.
Two recirculation pumps (G45A for Train 'A' and G45B for Train 'B') take suction from the containment sump and discharge to a common header, through the Recirculation Heat Exchanger, to the suction of the charging pumps for recirculation to the RCS and to the suction of the refueling water pumps for recirculation to the containment spray system.
B..
Circumstances Surrounding the Situation:
On October 26, 1992, utilizing a conservative interpretation of the Licensing basis for the recirculation pump IST wet test interval, it was determined that the inservice tests for the pumps would become overdue prior to the Unit 1 permanent shutdown scheduled for November 30, 1992 (October 28, 1992 for G45B and October 30, 1992, for G45A).
A plant shutdown to Mode 5 (Cold Shutdown) conditions would be required to test these pumps.
PRR No. 3 states, in part, "every refueling or once every two years."
SCE believes that a conservative interpretation of this statement requires that the test be performed at refueling intervals NOT TO EXCEED once every two years.
It is believed that this requirement was previously non-conservatively interpreted due to the ambiguous wording of PRR No. 3. Typical licensing basis wording states, in part, "every refueling not to exceed two years," when two years is intended to be the maximum interval between surveillances.
Approval of this temporary waiver of compliance is requested for a period not to exceed 40 days commencing on October 28, 1992, until Unit 1 enters Mode 5 which is expected to occur on or about December 1, 1992.
This will preclude an unnecessary reactor shutdown.
C.
Compensatory Actions Necessary:
During the effective period of this waiver, compliance with the TS 4.2.1 monthly recirculation pump testing requirements will continue. No compensatory actions are necessary based on the low probability of pump failure as a result of increasing the two year test interval by approximately one month.
D.
Preliminary Evaluation of the Safety Significance of this Request:
Continued operation of SONGS Unit 1 for an additional period of -40 days without performing a wet test is of insignificant safety significance for the following reasons:
o Unit 1 is provided with two independent and redundant trains of Emergency Core Cooling System (ECCS).
Either train is capable of.
mitigating any event requiring the use of the SI recirculation system.
o Based on a review of readily available TS 4.2.1 monthly test data for the period October 9, 1991 to October 8, 1992, it has been determined that the pumps have not degraded during this period of operation.
John B. Martin 4 -
October 27, 1992 0
A probabilistic risk assessment was performed to provide an estimate of the core damage risk attributable to this test frequency interval extension. This assessment conservatively concluded that this test interval extension would result ina mean core damage frequency increase of less than 5E-8 per year.
o Based on a review of readily available maintenance history, pump reliability and the ability of the pumps to start and function under containment sump flooding conditions is not suspect.
E.
Justification for the Duration of the Waiver:
The requested duration of this waiver is considered justified since there is no safety significance associated with operation in Modes 1 through 4 in this configuration. In addition, the requested.duration will allow continued Unit 1 operation until its scheduled permanent shutdown on November 30, 1992.
F.
Basis for No Significant Hazards
Conclusion:
10 CFR 50.92 defines that no significant hazards will occur if operation of the facility in accordance with the temporary waiver of compliances does not:
- 1.
Involve a significant increase in the probability or consequences of an accident previously evaluated; or
- 2.
Create the possibility of a new or different kind of accident from any accident previously evaluated; or
- 3.
Involve a significant reduction in a margin of safety.
As previously discussed, the plant is provided with two redundant and independent SI recirculation pump trains. Deferring the recirculation pump "wet" test frequency by a short term until the impending Unit 1 permanent shutdown on November 30, 1992, does not significantly decrease the reliability or availability of these pumps.
The change therefore does not significantly increase the probability or consequences of an accident previously evaluated; nor create the possibility of a new or different kind of accident from any previously evaluated; nor does it represent a significant reduction in a margin of safety..
G.
Basis for No Irreversible Environmental Consequences:
It has been determined that this temporary waiver of compliance involves no significant increase in the amounts, and no significant change in the types of any effluent that may be released offsite and that there is no significant increase in individual or cumulative occupational radiation exposure.
Accordingly, this temporary waiver of compliance meets the eligibility criteria for categorical exclusion set forth in 10 CFR Section 51.22(c)(9).
Pursuant to 10 CFR 51.22(b), no environmental impact statement or environmental assessment need be prepared in connection with the granting of the temporary waiver of compliance.
John B. Martin 5 -
October 27, 1992 The San Onofre Nuclear Generating Station Onsite Review Committee has reviewed and approved this Request for Temporary Waiver of Compliance.
If you have any questions or comments, or if you would like additional information, please let me know.
Sincerely, Document Control Desk, USNRC, Washington, D.C.
cc:
K. E. Perkins, USNRC, Region V J. 0. Bradfute, NRC Project Manager, San Onofre Unit 1 C. W. Caldwell, NRC Senior Resident Inspector, San Onofre Units 1, 2&3