ML20070N146
| ML20070N146 | |
| Person / Time | |
|---|---|
| Site: | South Texas  |
| Issue date: | 03/11/1991 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20070N145 | List: |
| References | |
| NUDOCS 9103220306 | |
| Download: ML20070N146 (3) | |
Text
_ _ _ _ _ _ _ _ _
/p **ey\\
UNITED 87Af t8
[
q NUCLEAR REGULATORY COMMISSION E
- 1 WMHING7086 D. C. Pe946 SAFETY EVALUATION BY THE OFFICE OF NUCLFAR REACTOR REGULATION RELATED TO AMENDMENT N05. 22 AND 12 TO FACILITY OPERATING LICENSE NOS. NPF-76 AND NPF-80 HOUSTON LIGHTING & POWER COMPANY CITYPUBLICSERVICEB0jRDOFSANANTONIO CENTRAL POWER AND LIGHT COMPANY r!TY OF AUSTIN. TEXAS DOCKET NOS. 50 496 AND S0-499 SOUTH TEXAS PROJECT UNITS 1 AND 2
1.0 INTRODUCTION
By application dated November 15, 1990 (ST-HL-AE-3627), as reviseo on January 17,.
1991 (ST-HL-AE-36'i), Houston Lighting & Power Company, et. al., (the licensee) requested change to the Technical Specifications (Appendix A to Facility Operating Licen r Nos, ilPF-76 and NPF-80) for the South Texas Project. Units 1 and 2.
The prossed changes would modify Technical Specification (TS) 4.4.6.2.2d to require that certain reactor coolant system (RCS) pressure isolatior, valves (PIVs)-be demonstrated operable prior to entering MODE 2.
Prior to this amendment, the PIVs had to be demonstrated operable within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> following valve actuation.
2.0 B_ACKGROUND On July 6,1990, the licensee concluded that its interpretation of Technical i
Specification (TS) 4.4.6.2.2d was incorrect and as such, there were at least two occasions when the TS was violated.
In accordance with 10 CFR 50.73, a Licensee Event Report (90-017) was womitted.
The licensee recognized that on certain occasions (e.g., startup from a refueling outage), it was not possible to comply in total with TS 4.4.6.2.2d without subjecting the plant to an additional pressure and temperature cycle.
Part of the corrective action plan by the licensee was to submit an amendment request to the NRC staff for a change to the TS.
During the first refueling outage on Unit 2 and while the license amendment request was in preparation,.the licensee concluded that during plant restart the surveillance required by TS 4.4.6.2.2d could not be completed within the allotted 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.
By letter dated November 19, 1990 (ST-HL-AE-3628), the licensee requested and was granted a Waiver of Compliance to extend the time 9103220306 910311 PDR ADOCK OM00493 P
ppg
o
+,
requirement from 24 to 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.
The staff concluded that the additional s.afety risk encountered during the additional 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> was offset, at least in part, by not subjecting the plant to another pressure / temperature cycle.
On November 29, 1990, the staff granted the Temporary Waiver c' Compliance (TWOC).
The TWOC allowed the staff sufficient time to process these technical specification changes in accordance with the procedures for review of proposed license amendments.
3.0 DISCUSSION Technical Specification 4.4.6.2.2 currently specifies that the Reactor Coolant System PIVs shall be demonstrated operable by verifying leakage to be within its limit at least once per 18 months, each time the plant is placed in cold shutdown for 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> if testing has not been accomplished in the preceding 9 months, 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> following valve actuation or flow through the valve, and following repair or replacement work.
The safety function of the surveillance tests is to ensure that the diska are fully seated prior to plant startup and that any leakage of high pressure flow from the Reactor Coolant System to the low pressure piping of the RHR system is within accc> table' criteria.
The current requirement of testing within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> of flow through the valves is especially burdensome when the plant is starting up from a refueling outage, during which all of the valves have been actuated to fulfill in service testing requirem:nts.
During heatup, temperature cross calibrations are performed which require a time period of 38 hcurs to reach normal operating temperature and pressure (NOT/NOP) from Mode 4 entry.
Three of the PIVs must be tested at NOT/NOP to avoid injection of water into the reactor vessel and therefore cannot be tested within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.
Also, if a problem which requires lengthy repair time is discovered af ter heat-up begins, the valves cannot be tested until maintenance is completed and NOT/NOP is reached.
In both of these cases, the unit must be cooled down again to ensure that the valves are not lef t closed and untested for greater than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.
Requiring that the pressure isolation valves be tested prior to Mode 2 :ntry eliminates the need to run extra pressure cycles on the equipment and allows for indefinite operation in Mode 3 during repairs.
4.0 EVALUATION l
Although probably delaying testing, the new surveillance requirement still l
fulfills the purpose of the technical specification by ensuring that the valves l
are fully closed prior to power operation and eliminates the need for going through an additional pressure cycle.
In addition, the design of South Texas minimizes the risk of overpressurization of piping.
Each system with PIVs covered by this technical specification is separated from the Reactor Coolant i
System by two normally closed leak-tested check valves within containment, and is isolated by an additional, normally closed, leak-tested check valve.
The effectiveness of the check valves to isolate the low pressure systems is further ensured by the remaining surveillance requirements of TS 4.4.6.2.2, which include the ASME,Section XI, leak testing requirements for Category A l
c.
-r.
g 3-t I
check ~ valves. -Based on the above, the staff determined that implementing i
the new surveillance requirement that leak testing be performed before entering Mode 2 rather.than within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, would not compromise the safety functions i
of the valves affected by this extension.
5.0 STATE CONSULTATION
5 In. accordance with the Commission's regulations, the Texas state official was notified of the proposed issuance of the amendments.
The State official had no comments.
6.0 ENVIRONMENTAL CONSIDERATION
The amendments change a requirement with respect _to installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20. -The NRC 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 the amendments involve no significant hazards consideration, and there has been no public comment on such finding (56 FR 4865).
Accordingly..the amendment meets 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 or enviror.aental aspessment need he prepared in connection with the issuance of the ase.idments.
7.0 CONCLUSION
The Commission 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 prcposed manner, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendments will not be inimical to the common defense and security or to the health and safety of the public.
Date:
March 11, 1991 Principal Contributor:
Donna Skay t
I?
l l'
.