ML20246F784
| ML20246F784 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 07/05/1989 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20246F777 | List: |
| References | |
| NUDOCS 8907140032 | |
| Download: ML20246F784 (3) | |
Text
..- -.
' *fn UNITED STATES i
f,i > c,
NUCLEAR REGULATORY COMMISSION l
- [, j WA$HINGTON, D. C. 20555
]
r. ~....,
ENCLOSURE SAFETY EVALUATION BY THE OFFICE OF, NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT NO.120 TO FACILITY OPERATING LICENSE NO. DPR-77 AND AMENDMENT NO.109 TO FACILITY OPERATING LICENSE N0. DPR-79 TENNESSEE VALLEY AUTHORITY SEQUOYAH NUCLEAR PLANT, UNITS 1 AND 2 DOCV.ET NOS. 50-327 AND 50-328
1.0 INTRODUCTION
By letter dated December 5,1988, the Tennessee Valley Authority (the licensee) requested a change to the Sequoyah Nuclear Plant, Units 1 and 2. Technical Specifications (TS).
The changes (1) delete Surveillance Requirement (SR) 4.6.3.4 on each containment purge isolation valve and (2) add SR 4.6.1.9.3 on each containment purge supply and exhaust isolation valve and Action statement "b" for these valves if they are not operable.
The purpose of the TS change was to reduce the leak rate test frequency for the containment purge supply and exhaust isolation valves and define a specific maximum leakage rate of 5 percent of the total containment leakage rate (La) for each of these valves.
The licensee's justifications for this TS change involves benefits and savings in the area of as low as reasonably achievable (ALARA) doses, plant safety, cost to the licensee and bringing the Sequoyah TS it.to agreement with the NRC Standard Technical Specification This is the licensee's TS change request 88-06.
2.0 EVALUATION The current TS do not define the allowable leakage rate for an individual purge valve to be considered operable.
The current TS only define purge valve operability in terms of the overall leakage contribution of all the purge valves to the combined leakage rate of the containment.
If the measured leakage rate of these penetrations exceeds 0.6 La these v41ves are inoperable and the plant is subject to a limiting condition for operation (LCO).
The proposed TS establishes a leokage limit of 0.05 La for an individual purge valve with a limiting condition for operation if this leakage limit is exeseded.
The proposed TS also retains the restrictions of the current TS with regard to the overall contribution of all the purge valves to the combined leakage of the containment.
8907140032 890705 DR ADOCK 0500 7
1
' The proposed TS also changes the current purge supply and eanaust isolation valves leakage test frequency.
The current SR 4.6.3.4 states that each con-tainment purge isolation valve be demonstrated operable (i.e., undergo an Appendix J Type C Leakage Test) within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> after each closing of the valve except when the valve is being useri for multiple cyclings. Any purge valve that has undergone multiple cyclirgs is required to be tested at least once every 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.
Operability is remonstrated by performance of a Type C leakage test to verify that the measured leakage rate from each purge valve, when added to the leakage rates for all other Type B and C penetrations, does not exceed 0.60 La.
The proposed TS would change the 24/72 hour test requirement discussed obove to a three month test interval.
Under the current TS, test personnel are required to enter the annulus at least three times each week for a minimum test duration of one hour.
This places test personnel in areas of low to intermediate radiation for prolonged periods of time.
Decreasing the test frequency reduces the number of times test personnel enter the annulus from 252 to 8 times over a 1 year time period.
The annual savings in net exposure to personnel is estimated to be 3 person - 1 Reducing the number of times test personnel enter the annulus also reduces i...
annual testing cost to the licensee by $290,000 for both units.
The proposed TS change also brings the SR into agreement with the requirements in the NRC STS.
The STS recognize two leak-test frequencies for purge supply dnd exhaust isolation valves: a 6-month test frequency for 42-inch purge valves and a 3-month test frequency for 8-inch purge valves. The STS also states that the measured leakage rate be less than or equal to 0.0S La for both size valves. The test requirements for the 42-inch purge valves would not be applicable to the proposed change because Sequoyah, by design, does not have 42-inch purge valves.
Sequoyah's purge valves range in size from 8 inches to 24 inches, and the licensee proposes to use the 3-month test frequency for these valves.
The proposal is in agreement with the NRC STS.
During the Type C leak test of Sequoyah's purge system containment isolation valves, a test connection valve is opened between the inboard and outboard purge isolation valves creating a containment leak path. While the test valve is open, the plant must enter a 1-hour LC0 (LC0 3.6.1.1).
The frequent entering and exiting of a limiting condition for operation to perform surveillance places an unnecessary burden on the plant operations staff. Changing the test interval to once every three months would alleviate placing the plant into frequent LCOs and would provide more freedom to the operators for monitoring plant conditions, thereby improving overall plant safety.
Since the proposed TS would result in benefits and savings in the areas of ALARA, plant safety, and bring the Sequoyah TS into agreement with the NRC STS, we conclude that TS change request 88-06 is acceptable.
^
3-3,0 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 effluents that may be released offsite, and that there is no significant increase 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 amendments 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 to be prepared in connection with the issuance of these amendments.
4.0 CONCLUSION
The Commi~ssion made a proposed determination that the amendment involves no significant hazards consideration which was published in the Federal Register (53 FR 53101) on December'30, 1988 and consulted with the' State of Tennessee.
No public comments were received 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 will not be endangered by operation in the proposed manner, and (2) public such activities will be conducted in compliance with the Commission's regulations, and the issuance of the 2;nendments will not be inimical to the r.ommon defense and security nor to the health and safety of the public.
5.0 REFERENCE Letter from M. J. Ray, Tennessee Valley Authority, to U.S. Nuclear Regulatory Commission,
Subject:
Sequoyah Nuclear Plant - Technical Specification Change 88-06, dated December 5, 1988.
Principal Contributor:
P. Hearn I
Dated: July 5, 1989 1
L