ML13330B551
| ML13330B551 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 08/26/1991 |
| From: | Krieger R SOUTHERN CALIFORNIA EDISON CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9108290269 | |
| Download: ML13330B551 (5) | |
Text
Southern California Edison Company SAN ONOFRE NUCLEAR GENERATING STATION P. 0. BOX 128 SAN CLEMENTE, CALIFORNIA 92674-0128 R. W. KRIEGER TELEPHONE STATION MANAGER (714) 368-6255 August 26, 1991 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D. C. 20555
Subject:
Docket No. 50-206 Request for Temporary Waiver of Compliance Level Transmitter Surveillances - Safety Injection San Onofre Nuclear Generating Station, Unit 1
References:
- 1)
Letter, R. W. Krieger (SCE) to J. B. Martin (NRC), Request for Temporary Waiver of Compliance, dated August 9, 1991
- 2)
Letter, R. W. Krieger (SCE) to J. B. Martin (NRC), Operable Level Transmitter - Safety Injection, dated August 9, 1991
- 3)
Letter, H. B. Ray (SCE) to USNRC Document Control Desk, Amendment Application 188, dated August 31, 1990 The purpose of this letter is to request a Temporary Waiver of Compliance for periods of 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> from the requirements of Technical Specification (TS) 3.0.3 without fully complying with the requirements of TS 3.3.1, "Safety Injection System and Containment Spray Systems - Operating Status," sections "A(3)", "B(1)" and "B(8)". We are submitting this request in accordance with guidance received from the SONGS Unit 1 Project Manager, Mr. George Kalman.
A.
Requirements For Which The Waiver Is Requested:
TS 3.3.1, defines the operability requirements for the Safety Injection System (SIS).
The objective of this TS is to ensure availability of the SIS while the reactor is critical.
TS 3.3.1.A.(3), requires in part, that interlocks associated with the SIS be maintained operable but does not provide an ACTION statement. This specification applies to the Volume Control Tank (VCT) level transmitters (LT-2550 and LT-1100) which actuate motor operated valves (MOV) as described below on low VCT level to protect the charging pumps from damage due to gas binding as a result of VCT hydrogen, and to assure a continued source of borated water from the Refueling Water Storage Tank (RWST).
TS 3.3.1.B establishes time limits for certain components to be removed from service for maintenance D1 K05002,9 PIR
Document Control Desk August 26, 1991 (similar to the ACTION requirements of the Standard TSs).
Section "B" allows one of eight specified components (or groups of components) to be removed from service at a time for a period not longer than 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.
Specifically, section B(1) allows one MOV at a time (either MOV 1100B or 1OOD) in the recirculation loop upstream of the charging pump suction header to be removed from service; and section B(8) allows one MOV at a time (either MOV 1100C or 1100E) in the VCT outlet line to the charging pump suction to be removed from service.
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, and that the unit be placed in COLD SHUTDOWN in the following 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />.
TS 4.1.1, "Operational Safety Items," Table 4.1.3, requires that the VCT level channels be surveillance tested (a loop channel test - injection of a simulated signal into the channel to verify response) once per month while Unit 1 is in POWER OPERATION (Mode 1) or STARTUP (Mode 2).
A temporary waiver of the shutdown requirements of TS 3.0.3 is requested in order to avoid unnecessary plant shutdowns which would otherwise be required since applicable OPERABILITY and ACTION requirements of TS 3.3.1 for the SIS cannot be fully satisfied during surveillance testing pursuant to TS 4.1.1, or during periods when one of the VCT level transmitters or the associated control loop may be inoperable for corrective maintenance. Each VCT level transmitter interlock actuates a pair of MOVs in a combination which precludes removing a VCT level transmitter from service without rendering the associated MOVs inoperable contrary to the requirements of the present TS 3.3.1.B (i.e, LT-1100 actuates MOVs 1100C and 1100D, and LT-2550 actuates MOVs 1100B and 1100E, respectively).
This action has the potential, in the event of a single failure of the redundant train during the periods each level transmitter is out-of service, to prevent automatic operation of the associated MOVs on low VCT level.
This would preclude: 1) aligning the RWST through the recirculation loop header to the suction of the charging pumps by opening MOV 1100D (or 1OOB), and 2) isolation of the VCT from the charging pump suction header by closing MOV 1100C (or 1100E) on low VCT level following certain small break Loss of Coolant Accident events in which safety injection actuation would not occur prior to emptying the VCT. The charging pumps could be damaged in the event they are aligned to an empty VCT.
Granting this waiver of compliance has the effect of avoiding plant shutdowns while the affected VCT level transmitter and its associated control loop is removed from service for surveillance testing and for the performance of any corrective maintenance which may become necessary. During the 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> periods when this waiver is being relied upon, one train of required systems and components will be maintained Operable.
Document Control Desk August 26, 1991 B.
Circumstances Surrounding the Situation:
On September 2, 1991, the surveillance interval for LT-2550 (including the allowable extension) will expire. Even though the present surveillance interval for LT-1100 would not expire until September 9th for the reasons described in References 1 and 2, SCE's practice is to perform both loop channel test surveillances sequentially on the same day. Additional reliance on this waiver will subsequently be required:
- 1) at monthly intervals in order to perform the monthly VCT level transmitter loop channel tests, and 2) any instances in which corrective maintenance is required on the VCT control loops.
A request to amend the Technical Specifications (Amendment Application No. 188) was submitted on August 31, 1990 (Reference 3).
The request is under review and was discussed with NRR in July, 1991.
We are committed to submitting a revision to the application by September 9, 1991, to expedite the review process. Section D, below, further describes the proposed changes.
Prompt approval of this temporary waiver of compliance is requested for periods not to exceed 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> beginning at 0600 on August 28th in order to perform the next LT-2550 and LT-1100 loop channel tests and to also be applicable to any subsequent surveillances and necessary corrective maintenance until Amendment Application No. 188 is issued, or denied.
Prompt approval would preclude an unnecessary reactor shutdown to HOT STANDBY (Mode 3) since it is considered to be safer to maintain the unit in the present configuration, during the period required to perform the surveillances and any necessary corrective maintenance, rather than to place the unit in a shutdown transient. The need for this waiver was unavoidable since the surveillances cannot be performed and the level transmitters restored to service within the one hour TS 3.0.3 action time limit.
C.
Compensatory Actions Necessary:
During the effective periods of this waiver all required systems and components of the unaffected train will be maintained operable.
D.
Preliminary Evaluation of the Safety Significance of this Request:
Continued operation with either VCT level transmitter inoperable for a period of 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> is of no safety significance for the following reasons:
o Unit 1 is provided with two independent and redundant trains of.
Emergency Core Cooling System (ECCS) (which includes safety injection), including the capability to realign the charging pump suction from the VCT (on low VCT level or safety injection ) to the RWST. Either train is capable of mitigating any event requiring the use of the ECCS. These provisions ensure that a single failure could not prevent completion of this aspect of a required safety function. In this regard, SCE has recently
Document Control Desk August 26, 1991 completed an ECCS single failure analysis and certain plant upgrades to assure completion of required ECCS functions in the event of a single failure.
o Consistent with these changes, SCE had previously concluded that a TS change was appropriate to preclude unnecessary entries into TS 3.0.3. In this regard, reference 3) submitted a proposed TS change which would modify the existing TS 3.3.1 and add TS 3.3.2 to be consistent with the Standard TSs for ECCS. Modifications made during the recent Cycle 11 refueling outage added VCT Level Transmitter, LT-2550, and the associated VCT outlet valve, MOV 1100E.
Although these components were not specifically addressed in the proposed TS change, the proposed change is based on the STS 72-hour ACTION statement for ECCS components. We plan to submit an updated revision of the proposed change on September 9, 1991, to include Cycle 11 modifications and to incorporate format changes requested by NRR. It is our understanding that NRR does not disagree with the application of the STS 72-hour ACTION statement to ECCS Components, as contained in the proposed change.
o The allowable out-of-service time (72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />) being proposed is of minimal safety significance when compared to the risks associated with initiating a plant shutdown for the purposes of testing these level transmitters. The risks for the allowable out-of-service time are also similar to that for any other one-of-two train systems or components having a 72-hour action statement. Further, the probability of core damage as a result of the inoperability of LT-2550 or LT-1100 for up to 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> has been calculated to be approximately 5E-7 per year.
o The compensatory measures described above provide added assurance that required ECCS functions will be satisfied in the remote event that they are required.
E.
Justification for the Duration of the Waiver:
This temporary waiver of compliance is requested for periods of 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />, commencing at 0600 on August 28, 1991, and for any subsequent instances in which the VCT level transmitter control loops may be inoperable for subsequent surveillances or corrective maintenance, until Amendment Application No. 188 is in effect, or is denied. We believe that this will provide sufficient time to perform the LT-2550 and LT 1100 loop channel test surveillance and any corrective maintenance.
The requested duration of this waiver was considered justified since there was no safety significance associated with operation in Modes 1 or 2 in this configuration.
e Document Control Desk August 26, 1991 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 ECCS trains. The short term inoperability of one of two independent VCT level transmitters 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:
This request does not involve a change in the installation or use of the facilities or components located within the restricted areas as defined in 10 CFR 20. 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.
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.
- erely, cc:
R. P. Zimmerman, USNRC, Region V C. W. Caldwell, USNRC Senior Resident Inspector George Kalman, USNRC Project Manager, Unit 1 M. J. Virgilio, USNRC - NRR