ML20237A385
| ML20237A385 | |
| Person / Time | |
|---|---|
| Site: | Salem  |
| Issue date: | 08/06/1998 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML20237A381 | List: |
| References | |
| NUDOCS 9808140015 | |
| Download: ML20237A385 (5) | |
Text
..
aus k
UNITED STATES l
p NUCLEAR REGULATORY COMMISSION U
'E WASHINGTON, D.C..ansas -1
\\...../
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION l.
l RELATED TO AMENDMENT NOS. 213 AND 193 TO FACILITY OPERATING t
LICENSE NOS. DPR-70 AND DPR-75 PUBLIC SERVICE ELECTRIC & GAS COMPANY PHILADELPHIA ELECTRIC COMPANY DELMARVA POWER AND LIGHT COMPANY ATLANTIC CITY ELECTRIC COMPANY l
SALEM NUCLEAR GENERATING STATION. UNIT NOS.1 AND 2 DOCKET NOS. 50-272 AND 50-311 i
l
1.0 INTRODUCTION
By letter dated November 14,1997, the Public Service Electric & Gas Company (the licensee) submitted a request for changes to the Salem Nuclear Generating Station, Unit Nos.1 and 2, Technical Specifications (TSs). The requested changes would pmvide TS surveillance requirements for the service water (SW) accumulator vessels. Specifically, surveillance requirements are provided for vessel level, pressure and temperstere, and discharge valve response time. The surveillance requirements are included in TS 3/4.6.1.1 and 3/4.6.2.3, and the applicable Bases sections are expanded to provide supporting information.
2.0 EVALUATION Backaround l
The SW system for each of the two Salem units is an open-loop cooling water system consisting of two separate headers that are normally cross connected. Each unit has six service water pumps, with three pumps aligned to each of the service water headers. There are five l
Containment Fan Cooler Units (CFCUs) for each unit with each service water header providing cooling water to two of the CFCUs; the fifth CFCU receives cooling water from both of the service water headers.
As part of the resolution of NRC Generic Letter (GL) 96-06, " Assurance of Equipment Operability and Containment Integrity During Design-Basis Accident Conditions," the licensee modified the CFCU piping on each unit to include two SW accumulator vessels and fast acting discharge l
valves. One 15,000 gallon capacity water accumulator tank is installed on each of two SW headers to the CFCU inlet pipink. The modification precludes the potential for water hammer events that could challenge CFCU piping integrity and CFCU containment heat removal capability. The modification is also designed to maintain sufficient system pressure to prevent water column separation voiding and two-phase flow in this piping during accident conditions.
ooh 0j72 O
1 I These modifications were reviewed and approved by the NRC staff and are documented in the NRC's safety evaluation supporting amendment nos.196 and 179, dated June 19,1997, for Salem Units 1 and 2, respectively. The licensee discussed the need for additional administrative controls regarding the operation of the system in its March 27,1997 (LR-N97171), and April 24, 1997 (LR-N97268), submittals supporting the modifications. The licensee committed to incorporate the new administrative controls into the TSs within 90 days of entering Mode 2 (startup) on each unit.
l In the November 14,1997 letter, the licensee requested a revision to the Salem Unit 1 and 2 TSs to provide surveillance requirements (SRs) that would codify the commitment to incorporate the existing administrative procedural controls. The proposed SRs include requirements for accumulator vessel level, temperature, nitrogen overpressure and discharge valve response j
time. The purpose of the SRs is to provide added assurance that the SW accumulator vessels j
and associated discharge valves will be maintained in accordance with the design criteria to perform their safety function of maintaining the cooling water to the Containment Fan Coolers filled and in a subcooled condition as assumed during accident conditions. Specifically, the
]
proposed SRs provide added assurance that the SW accumulator tank level, temperature and pressure will be maintained in the range established by ther design. Additionally, an SR to test the accumulator vessel discharge valve response time provides added assurance that the discharge valves will be capable of opening within the time assumed by the accident analysis.
i l
The proposed SRs are new and do not replace or modify any existing SRs. Monitoring the SW accumulator vessel level, temperature and pressure, and periodically verifying the SW accumulator discharge valve response time provides assurance that the Containment Cooling Limiting Conditions for Operation (LCO) are met and are therefore appropriate for consideration as TS Surveillance Requirements.
SW Accumulator Vessel Level The licensee proposed to modify SR 4.6.2.3, " Containment Cooling Systems," to require SW accumulator vessel level be verified to be between 226 inches and 252 inches, inclusive, at least once per 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. Accumulator vessel levelis verified to ensure a sufficient inventory is maintained in each tank to supply cooling water to the CFCUs during a LOCA/ LOOP until the SW pumps are re-powered from vital buses. The minimum vessel level also provides adequate inventory to prevent complete draining of a vesselif the vossel discharge valve fails open and the maximum level is set low enough to prevent a significant change in nitrogen pressure during l
the injection phase of operation.
The 12-hour surveillance frequency is similar and comparable to the Salem SR for the emergency core cooling system (ECCS) accumulator vessel, in addition, the TS surveillance frequency is shorter than the current daily SR committed to in letter LR N97268, dated l
April 24,1997.
The staff finds the proposed requirements for SW accumulator level and its associated surveillance frequency to be acceptable.
l I
3-SW AccumulatorVessel Pressure The licensee proposed to modify SR 4.6.2.3, " Containment Cooling Systems," to require SW accumulator vessel pressure be verified between 135 pounds per square inch (gauge) (psig) and 160 psig, inclusive, at least once per 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. The minimum accumulator vessel pressure is verified to ensure a sufficient pressure is maintained in each vessel to maintain CFCU fluid pressure above saturation during LOOP /LOCA conditions. The maximum vessel pressure precludes the entire contents of the tank from being discharged into the CFCU cooling loop. The maximum pressure is within the design of the cooling system supplying cooling water to the CFCUs.
l The 12-hour surveillance frequency is similar and comparable to the Salem SR for the ECCS accumulator vessel. In addition, the TS surveillance frequency is shorter than the current daily SR frequency committed to in letter LR-N97268, dated April 24,1997.
The staff finds the proposed requirements for SW accumulator pressure to be acceptable.
SW Accumulator Vessel Temperature The licensee proposed to modify SR 4.6.2.3, " Containment Cooling Cystems," to require SW accumulator vessel temperature be verified between 55 *F and 95 'F, inclusive, at least once per 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. Nitrogen solubility increases with decreasing inventory temperature. As the inventory is discharged into the CFCU cooling system piping, the pressure will decrease and nitrogen will come out of solution and become entrained in the flow. The minimum accumulator vessel temperature is verified to ensure that the amount of nitrogen that comes out of solution will not significantly affect the CFCU heat removal function. The upper temperature limit is verified to ensure the CFCU containment heat removal capability is maintained as the inventory is injected into the CFCU cooling system piping.
The 12-hour surveillance frequency is similar and comparable to the Salem SR for the ECCS accumulator vessel. In addition, the TS surveillance frequency is shorter than the current daily SR frequency committed to in letter LR-N97268, dated April 24,1997.
The staff finds the proposed requirements for SW accumulator temperature to be acceptable.
SW Accumulator Vessel Dischame Valve Response Time l
The licensee proposed to modify SR 4.6.2.3," Containment Cooling Systems," to require SW l
accumulator discharge valve response time be verified within the appropriate limits by test at least once every 18 months. Discharge valve response time is critical to assuring the vessel inventory injection occurs on a LOOP /LOCA prior to the CFCU header pressure decaying below the saturation pressure. The design analysis requires that on the initiation of a loss of an oN*
power signal, the vessel discharge butterfly valves stroke open to the 45 degree position in in than or equal to 1.5 seconds. Valve position indication is verified during testing by a limit switch that is included in the valve installation. Acceptable response time testing of these valves will ensure the inventory of the accumulator vessel is discharged into the CFCU piping to preclude CFCU flow column separation and two phase flow conditions during a LOOP /LOCA.
I l
1 4
4 The 18-month surveillance frequency is consistent with Salem TS surveillance requirements for engineered safety features which are on an 18-month frequency. In addition, the TS surveillance frequency is consistent with the frequency committed to in letter LR-N97268, dated April 24, 3
1997.
)
i The staff finds the proposed requirements for SW accumulator temperature to be acceptable.
Containment Intearity L
The licensee proposet changes to TS 4.6.1.1 and Basis 3/4.6.1.1, Containment Integrity," to reflect the fact that prc;er operation of the SW accumulator system, serving the CFCU cooling l
loops, is required to aswre the continued integrity of the CFCU cooling loops during cer1ain accident conditions. The OFCU cooling loops inside containment are containment isolation barriers. If they were to rurore d':.ing an accident, containment integrity would be threatened.
The proposed additional surveillance requirements,4.6.1.1.c. and 4.6.1.1.d., simply refer to the new surveillance requirements for the service water accumulator system,4.6.2.3.a. and
]
4.6.2.3.d., respectively. This ties containment integrity to the successful surveillance and operability of the service water accumulator system, which the staff finds to be an appropriate way to assure containment integrity. Therefore, the staff finds the proposed changes to TS 4.6.1.1 and Basis 3/4.6.1.1 to be acceptable.
l Administrative and Bases Chanaes The staff has also reviewed the proposed administrative changes (i.e., renumbering) to SR 4.6.2.3 and the changes to Bases Section 3/4.6.2.3 for Containment Cooling System, regarding SW accumulator vessel level, pressure, and temperature and accumulator discharge valve response time and found them acceptable.
Conclusion The staff has reviewed the proposed changes to the TS surveillance requirement SR 4.6.2.3 for the Containment Cooling System and its associated Bases. Based on its review, the staff concluded that the proposed changes to monitor SW accumulator vessel level, pressure and temperature and to test the response time of the SW accumulator discharge valves meet the requirements of 10 CFR 50.36, satisfy the licensee's commitment to codify their existing administrative controls regarding the SW accumulator vessels and associated discharge valves, and are acceptable. The proposed changes establish requirements that are appropriate and necessary for protecting the SW system from the effects of waterhammer and two phase flow conditions, thereby assuring system operability and containment integrity during LOCA/ LOOP.
I Failure to meet any of these SRs will render the associated SW accumulator vessel inoperable.
Under these conditions, containment integrity requirements for those CFCU cooling loops exclusively supplied by the inoperable accumulator vessel are not met. The affected CFCU
.I cooling loops will be removed from service and remain isolated to maintain containment integrity.
l 1
The staff also reviewed the proposed changes to the numbering of Surveillance Requirement 3/4.6.2.3 and has found them acceptable.
I i
, The NRC staff has reviewed the proposed changes to the proposed TS surveillance requirement SR 4.6.1.1 for Containment integrity and its associated Bases. Based on its review, the staff finds that the proposed changes assure the integrity of the CFCU cooling loops during specific accident conditions. The staff finds that the addition of the surveillance requirements with references to requirements. In SR 4.6.2.3 for containment penetrations associated with the CFCUs will ensure that containment integrity conditions will be met. Therefore, the staff finds that the proposed changes are acceptable.
The licensee also expanded the Bases sections for these TS Containment integrity TS 3/4.6.1.1 and Containment Cooling System TS 3/4.6.2.3. to provide supporting information regarding the SRs. The staff finds the added information incorporated into the TS bases to be acceptable.
3.0 STATE CONSULTAT!ON In accordance with the Commission's regulations, the New Jersey State official was notified of
. the proposed issuance of the amendments. The State official had no comments.
4.0 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 and change surveillance requirements. 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 previoush issued a proposed finding that the amendments involve no significant hazards consideration, and there has been no public comment on such finding (63 FR 4322). 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 or environmental assessment need be prepared in connection with the issuance of the amendments.
5.0 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 proposed 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.
Principal Contributors: C. Gratton F. Gee J. Pulsipher Date: August 6, 1998 I
I l