ML20057F416
| ML20057F416 | |
| Person / Time | |
|---|---|
| Site: | South Texas  |
| Issue date: | 10/07/1993 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20057F388 | List: |
| References | |
| NUDOCS 9310150257 | |
| Download: ML20057F416 (5) | |
Text
[" *%
g, _
.. s 5
?>
UNITED STATES
('
'j NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C 2055Ho01 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NOS. 55 AND 44 TO FACILITY OPERATING LICENSE NOS. NPF-76 AND NPF-80 HOUSTON LIGHTING & POWER COMPANY CITY PUBLIC SERVICE BOARD OF SAN ANTONIO CENTRAL POWER AND LIGHT COMPANY Q TY OF AUSTIN. TEXAS DOCKET N05. 50-498 AND 50-499 SOUTH TEXAS PROJECT. UNITS 1 AND 2
1.0 INTRODUCTION
By application dated August 10, 1992, as supplemented by letter dated September 14, 1993, Houston Lighting & Power Company, et.al., (the licensee) requested changes to the Technical Specifications (Appendix A to Facility Operating License Nos. NPF-76 and NPF-80) for the South Texas Project, Units 1 and 2.
The proposed changes would revise Technical Specifications 3/4.4.4 and 3/4.4.9 to incorporate the recomendations provided in Generic Letter 90-06.
Additional changes to improve clarity and accuracy are also included.
2.0 BACKGROUND
On June 25, 1990, the staff issued Generic Letter (GL) 90-06, " Resolution of Generic Issue 70, ' Power-Operated Relief Valve and Block Valve Reliability,*
and Generic Issue 94, ' Additional Low-Temperature Overpressure Protection for Light-Water Reactors,' Pursuant to 10 CFR 50.54(f)." The GL represented the technical resolution of the above mentioned generic issues.
Generic Issue 70, " Power-Operated Relief Valve and Block Valve Reliability,"
involves the evaluation of the reliability of power-operated relief valves (PORVs) and block valves and their safety significance in PWR plants. The GL discussed how PORVs are increasingly being relied on to perform safety-related functions and the corresponding need to improve the reliability of both PORVs and their associated block valves. Proposed staff positions and improvements to the plant's technical specifications were recommended to be implemented at all affected facilities. This issue is applicable to all Westinghouse, Babcock & Wilcox, and Combustion Engineering designed facilities with PORVs.
Generic Issue 90, " Additional Low-Temperature Overpressure Protection for Light-Water Reactors," addresses concerns with the implementation of the requirements set forth in the resolution of Unresolved Safety Issue (USI) 9310150257 931007 PDR ADOCK 05000498 P
' A-26, " Reactor Vessel Pressure Transient Protection (Overpressure Protection)." The GL discussed the continuing occurrence of overpressure events and the need to further restrict the allowed outage time for a low-temperature overpressure protection channel in operating modes 4, 5, and 6.
This issue is only applicable to Westinghouse and Combustion Engineering facilities.
By [[letter::ST-HL-AE-4176, Submits Supplemental Info to 901221 Application for Amends to Licenses NPF-76 & NPF-80,changing TS 3/4.4.4 & 3/4.4.9 Re PORV & Block Valve Reliability Per GI 70 (NUREG-1316) & GI 94 (NUREG-1326),identified in Generic Ltr 90-06|letter dated August 10, 1992]] (ST-HL-AE-4176), Houston Lighting & Power Company, et. al., (HL&P) requested changes to the South Texas Project, Units 1 and 2 technical specifications in response to GL 90-06.
The licensee had previously responded to GL 90-06 in a letter dated December 21, 1990 (ST-HL-AE-3642). The staff determined that portions of this submittal were acceptable and issued Amendment Nos. 31 and 22 to Facility Operating License Nos. NPF-76 and NPF-80 for the South Texas Project, Units 1 and 2 on November 8, 1991. These amendments consisted of changes to the TS to permit full operability testing of an inoperable PORV following maintenance.
These amendments approved only a portion of the requested changes. Additional justification for the unapproved portion of the proposed amendment was requested per teleconference by the staff and was provided in the August 10, 1992, submittal. This safety evaluation addresses the remainder of the changes requested.
3.0 EVALUATION 3.1 Evaluation for Generic Issue 70 The actions proposed by the NRC staff to improve the reliability of PORVs and block valves represent a substantial increase in overall protection of the public health and safety and a determination has been made that the attendant costs are justified in view of this increased protection. The technical findings and the regulatory analysis related to Generic Issue 70 are discussed in NUREG-1316, " Technical Findings and Regulatory Analysis Related to Generic Issue 70 - Evaluation of Power-0perated Relief Valve Reliability in PWR Nuclear Power Plants."
The technical specification (TS) changes in response to Generic Issue 70,
" Power-0perated Relief Valve and Block Valve Reliability," consist of the following changes to TS 3/4.4.4, " Relief Valves." An assessment of the proposed TS against the model TS of GL 90-06 for a Westinghouse plant follows.
1.
LCO 3.4.4 and Action Statement a. are revised to change all references to PORVs from "all" to "both" since the design of STP includes only two PORVs.
2.
Action Statement a. is revised by adding a statement that requires power to be maintained to block valves which have been closed due to excessive PORY leakage. This requirement ensures that the block valves are not rendered inoperable and is consistent with GL guidance.
3.
Action Statements a.,
b., and c. are revised such that they terminate in HOT SHUTDOWN within six hours of the preceding action instead of s
- terminating in COLD SHUTDOWN within 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br /> of the preceding action.
This is necessary since the applicability requirements of the LCO do not extend past the hot standby mode and is consistent with GL 90-06 guidance.
4.
Action Statement c. is revised to require that when both PORVs are inoperable, either of the PORVs be restored within an hour rather than both. The GL recomends this action to provide for the removal of power from a closed block valve as additional assurance to preclude any inadvertent block valve opening at a time when the PORY may not be closed due to maintenance to restore it to an operable condition.
5.
Action Statement d. is split into two action statements for clarification: one action statement applies when one block valve is inoperable and another action statement applies when both valves are inoperable.
The change submitted for Action Statement d. deviates slightly from the guidance in the GL in the direction for positioning of the PORY switches in the event of inoperable block valves. The GL guidance is to place the PORV in manual control to preclude its automatic opening and subsequent potential for a stuck-open PORV. The licensee proposes to place the PORV switches in the "close" position in such circumstances. This will likewise preclude automatic PORY opening and the subsequent potential for a stuck-open PORV when the block valve is inoperable and not closed.
This is consistent with the intent of the GL and is acceptable.
6.
The licensee originally proposed to revise Surveillance Requirement 4.4.4.1.b by adding the statement "during modes 3, 4, or 5" to the requirement to operate the valve through one complete cycle.
This deviated from the GL guidance which recommends that Mode 3 or Mode 4 is the preferred test mode. The reasons for Mode 3 or 4 testing are: (1) to verify the capability of the valves to function in an environment more representative of operating conditions, and (2) to perform the test prior to establishing conditions where the PORVs are required for low-temperature overpressure protection. After discussions with the staff, the licensee supplemented its response by letter dated September 14, 1993, to remove the specific mode requirements and return to the original language.
In this letter, the licensee comitted to administratively control the pressurizer PORV testing and modify procedures to include a specific temperature range to meet the intent of GL 90-06. The licensee will ensure operability of the PORVs by stroke testing the PORVs prior to establishing conditions when the PORVs are used for low temperature over pressure protection.
This is consistent with the intent of the GL and is acceptable.
7.
Surveillance Requirement 4.4.4.1.a is revised by adding the statement "on the PORY actuation channel" to enhance clarity and provide consistency with Surveillance Requirement 4.4.9.3.1.b.
There is no change to the existing requirements.
s
4 -
8.
Surveillance Requirement 4.4.4.2 is revised by deleting the statement "with power removed". This statement is not required since it is i
incorporated into the requirements of ACTION b. and c. of 3.4.4.
The revised surveillance requirement is consistent with GL 90-06 guidance.
9.
Surveillance Requirements 4.4.4.1.b and 4.4.4.3, as provided in the changes recommended in GL 90-06, are not incorporated in the STP technical specifications. Surveillance Requirement 4.4.4.1.b applies to plants with air-operated PORVs while STP uses solenoid operated PORVs.
Surveillance Requirement 4.4.4.3 applies to plants with non-safety grade power while the STP PORVs are powered from class IE buses.
10.
Bases 3/4.4.4 is expanded to identify the major functions for which operability of the PORV and block valves are determined. The proposed Bases deviates from the guidance in GL 90-06 in that automatic control of PORVs is not listed as a function on which operability of the PORY is based.
Inoperability of the PORVs automatic function during normal operation does not result in inoperability of the PORY manual operation.
This clarification is consistent with the STP design.
The staff has reviewed the licensee's proposed modifications to the STP technical specifications. Since the proposed modifications are consistent with the staff's position previously stated in the GL and found to be justified in the above mentioned regulatory analysis, the staff finds the i
proposed modifications to be acceptable.
3.2 Evaluation for Generic Issue 94 The actions proposed by the NRC staff to improve the availability of the low-temperature overpressure protection (LTOP) system represents a substantial i
increase in the overall protection of the public health and safety and a i
determination has been made that the attendant costs are justified in view of i
this increased protection. The technical findings and the regulatory analysis related to Generic Issue 94 are discussed in NUREG-1326, " Regulatory Analysis l
for the Resolution of Generic Issue 94, Additional Low-Temperature Overpressure Protection for Light-Water Reactors."
i t
By letter dated December 21, 1990, the licensee submitted its original response to GL 90-06 and requested changes to the technical specifications.
By letter dated November 8, 1991, the NRC issued Amendment Nos. 31 and 22 to the STP license approving some of these requests. These amendments revised Technical Specification 3.4.9.3 to resolve the concerns addressed by Generic Issue 94 and to address a conflict in the TS between TS 3.4.9.3 and TS 4.0.5.
The staff concluded in its safety evaluation that RHR relief valves are an acceptable alternative to the PORVs for LTOP protection for a period not to exceed seven days.
In the August 10, 1992, submittal the licensee requested a revision to TS Bases 3/4.4.9 to add details concerning the use of RHR relief valves to provide cold overpressure mitigation system during the stroke testing of inoperable PORVs consistent with TS 3.4.3.3 as approved in l
Amendment Nos. 31 and 22. This clarification is consistent with operation as
[
described in the Safety Evaluation related to issuance of Amendment Nos. 31 and 22 and is acceptable.
An additional revision to TS 3/4.4.9 was proposed. Technical Specification Figure 3.4-4, " Nominal Maximum Allowable PORY Setpoint for the Cold Overpressure System," is added to the figures listed in Surveillance Requirement 4.4.9.1.2 that are updated based on the results of the reactor pressure vessel (RPV) irradiation surveillance program. The change is made to emphasize the need to update the figure and the allowable PORY setpoint based on results of the RPV irradiation surveillance program. This change is acceptable.
4.0 STATE CONSULTATION
In accordance with the Comission's regulations, the Texas State official was notified of the proposed issuance of the amendment. The State official had no coments.
5.0 ENVIRONMENTAL CONSIDERATION
The amendment changes a requirement with respect to installation or use of a facility compenent located within the restricted area as defined in 10 CFR Part 20 and changes surveillance requirements. The NRC staff has determined that the amendment involves 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 Comission has previously issued a proposed finding that the amendment involves no significant hazards consideration, and there has been no public coment on such finding (58 FR 32384). Accordingly, the amendment meets the eligibility criteria for l
categorical exclusion set forth in 10 CFR 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 issuance of the amendment.
6.0 CONCLUSION
The Comission 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, (2) such activities will be conducted in compliance with the Comission's regulations, and (3) the issuance of the amendment will not be inimical to the comon defense and security or to the health and safety of the public.
Principal Contributor: Donna Skay, PDIV-2/NRR Date:
October 7, 1993 t