ML20235U977
| ML20235U977 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 02/28/1989 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20235U974 | List: |
| References | |
| NUDOCS 8903090461 | |
| Download: ML20235U977 (4) | |
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' 'n NUCLEAR REGULATORY COMMISSION WASHING TON, D. C. 20555 ENCLOSURE 3 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT NO. 101 TO FACILITY OPERATING LICENSE NO. OPR-77 AND AMENDMENT NO. 90 TO FACILITY OPERATING LICENSE NO. DPR-79 TENNESSEE VALLEY AUTHORITY SEQUOYAH NUCLEAR PLANT, UNITS 1 AND 2 DOCKET NOS. 50-327 AND 50-328
1.0 INTRODUCTION
By letter dated August 10, 1988, the Tennessee Valley Authority (TVA) proposed change 88-22 to the Technical Specifications (TS) for Sequoyah Units 1 and 2.
The proposed changes would add requirements for certain containment.1 solation valves to exclude them from the Appendix J Type C Testing Requirements.
The changes would revise containment system surveillance requirements (SR) 4.6.1.2.g and 4.6.3.2 and Table 3.6-2, " Containment Isolation Valves," to provide additional surveillance testing for the residual heat removal (RPR) spray lines (penetrations X-49A and X-498) and the normal charging containment isolation valve.
2.0 EVALUATION According to Appendix J of 10 CFR Part 50, the leakage rate Type C tests of containment isolation valves shall be performed to demonstrate the leak-tight integrity of the valves.
There are, however, isolation designs, whereby the leak-tight integrity of isolation valves can be demonstrated without a Type C test.
Containment isolation valves that use a water seal for containment isolation are, in accordance with Appendix J, an acceptable isolation barrier without the Type C test when the following conditions are met:
a.
It has been demonstrated that the water leakage rate of the valve that maintains the water seal does not exceed those specified in the TS or associated basis; and b.
The valve seal water system water inventory is sufficient to assure the sealing function for at least 30 days at a pressure of 1.10 Pa.
TVA has designated the available remote-manual valve on each of the two RHR spray lines for each unit as outboard containment isolation valves.
The inboard containment isolation valves are check valves.
This designation ensures the containment isolation design of penetrations X-49A and X-49B are in compliance with General Design Criterion (GDC) 56, Primary Containment Isolation, of Appendix A to 10 CFR Part 50.
TVA stated in its sute 1 91 that a water leg is maintained under normal plant operation in the risers for the RHR spray lines between the remote-manual valves and the containment.
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These RHR spray system outboard containment isolation valves have a water seal system and are not Type C tested.
TVA proposed that the motor-operated remote-manual valves be leak tested with water to verify therE is sufficient fluid inventory in the risers to maintain a water seal on the valves for 30 days even after shutoff of an RHR pump. This should ensure there will be no leakage of containment atmosphere to the environment for 30 days after an accident through these penetrations until the pressure in containment is. down to zero gauge pressure.
The proposed changes meet the requirements in Appendix J; therefore, the staff concludes that the proposed changes are acceptable.
The frequency' of testing the RHR spray system outboard containment isolation valves was discussed with the licensee by telephone conference calls on December 12 and 21, 1988.
These valves are leak-rate tested once every two years. This is in accordance with the schedule for Type C testing for containment isolation valves in Appendix J.
The column of water on these valves is pressure checked when the valves are stroked in accordance with Section XI of the ASME Code. Because these valves are interlocked with the RHR recirculation valves for the containment sump, these valves are stroke tested once a quarter when the plant is in Mode 5.
The valves may not be opened or stroked in Modes 1 to 4, which results in long intervals between the water column verification test for the 30 day water seal.
In order to prevent the loss of the water seal the licensee has designed the RHR system to pressurize any potential leakage path through the outboard isolation valve with the RHR pump or the static head of the refueling water storage tank (RWST).
If the RHR system is operating, the RHR pumps seal the valve by pressurizing the valve boundary to a pressure that far exceeds the containment accident pressure; thereby, preventing any outleakage from the containment.
If the RHR system is not operating, any leakage path outward from the valve would be sealed due to static head the RWST exerts on the RHR system.
The static pressure head due to the difference in elevation between the RWST and the outboerd isolation valve easily exceeds the containment design pressure of 12 psig. Since the outboard isolation valve and its water seal are pressurized by pressure sources that exceed the containment design pressure, the staff concludes that the frequency of testing the RHR outboard containment isolation valves is acceptable.
TVA also designated one of the outboard automatic isolation valves (FCV-62-90) as the outboard containment isolation barrier for the normal charging line (penetration X-16).
This designation ensures the containment isolation design for this penetration is in compliance with GDC 55, Reactor Coolant Pressure Boundary Penetrating Containment. This valve is not subject to Type C testing because a water seal is provided on this penetration after an accident with a guaranteed 30-day water supply and an injection pressure greater than 1.1 Pa as a result of the continuous operation of the centrifugal charging pump, even with consideration of a single active failure.
The staff concluded in Section 3.6.1.2 of the Safety Evaluation Report dated May 18, 1988 for TVA's Sequoyah Nuclear Performance Plan (NUREG-1232, Volume 2) that the new I
designation of FCV-62-90 as a containment isolation valve, subject to appropriate operability, surveillance, and testing requirements, renders the isolation design for this penetration acceptable and in compliance with the requirements of GDC 55.
TVA stated that the proposed addition of surveillance
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requirement 4.6.3.2.e and the addition of FCV-62-90 to Table 3.6-2 will provide long-term assurance that operability and surveillance testing requirements are maintained.
The current SRs 4.6.3.2.a. b, c, and d require testing of each conta Nment isolation valve listed in Table 3.6-2, Containment Isolation Valves, by verifying that the appropriate isolation test signal actuates the containment isolation valve to its isolation position. TVAhasproposed(1)addingthe requirement to verify the Normal Charging Isolation valve actuates to its closed position on a safety injection test signal and (2) adding the valve to Table 3.6-2 under the group "other."
Table 3.6.2 is organized into Phase "A,"
Isolation Valvess Phase "B" Isolation Valves, Phase "A" Containment Vent Isolation Valves and Other Valves.
The Normal Charging Isolation valve is actuated by the safety injection signal; therefore, the appropriate place for the valve in Table 3.6-2 is under the group "other" as proposed by TVA.
By telephone conference call on December 7, 1988, TVA stated that the Sequcyah Final Safety Analysis Report (FSAR) does not (1) list valve FCV-62-90 as the outboard containment isolation for penetration X-16, (2) state that the safety injection signal actuates the valve, or (3) state that the valve closes in 12 seconds for both units. TVA stated that this information will be included in the next update of the FSAR.
TVA's proposal will require a containment isolation functional test of the Normal Charging Isolation valve by the appropriate test signal.
This will assure that the valves are operable when needed. The frequency of the tests is consistent with that for testing the other contair. ment isolation valves. The maximum isolation time far the valve is a fast closing time for valves of this class which do not connect between the containment atmosphere and the environment. This valve connects between the RCS and a closed system outside containment.
Therefore, based on the above, the staff finds the proposed changes for the Normal Charging Isolation valve acceptable, and concludes that proposed TS change 88-22 is acceptable.
3.0 ENVIRONMENTAL CONSIDERATION
These amendments involve a change to a requirement with respect to the installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 and changes to the surveillance requirements.
The staff has determined that the amendments involve no significant increase in the amounts, and no significant change in the types, of any ef4 'uents that may be released offsite, and that there is no significant increaw in individual or cumulative occupational radiation exposure.
The Commission has previously issued a proposed finding that these amendments involve no significant hazards consideration and there has been no public comment on such finding. Accordingly, the cmendments meet the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9).
Pursuant to 10 CFR 51.22(b), no environmental impact statement nor environmental assessment need be prepared in connection with the issuance of these amendments.
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4.0 CONCLUSION
The Commission has made a proposed determination that the amendment involves no significant hazards consideration which was published in the Federal Register (53 FR 34614) on September 7, 1988.
The Commission also consulted with the State of Tennessee.
No put,lic comments were received in response to the
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notice in the Federal Register and the State of Tennessee did not have any comments.
- The staff has concluded, based on the considerations discussed above, that:
(1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, and (2) such activities will be conducted in compliance with the Commission's regulations, and the issuance of the amendments will not be inimical to the common defense and security nor to the health and safety of the public.
Principal Contributor:
P. Hearn Dated:
February 28, 1989 l_