ML20136F575
| ML20136F575 | |
| Person / Time | |
|---|---|
| Site: | Saint Lucie  |
| Issue date: | 12/16/1994 |
| From: | NRC |
| To: | |
| Shared Package | |
| ML20136C539 | List:
|
| References | |
| FOIA-96-485 NUDOCS 9703170007 | |
| Download: ML20136F575 (5) | |
Text
o SAFETY EVALUATION CONTAINMENT SYSTEMS AND SEVERE ACCIDENT BRANCH DIVISION OF SYSTEMS SAFETY AND ANALYSIS OFFICE OF NUCLEAR REACTOR REGULATION ST. LUCIE UNITS 1 & 2 1.0 INTRODtJCTION By application dated November 2, 1994, the Florida Power & Light Company (the licensee) requested changes to the St. Lucie Units 1 & 2 Technical Specifications (TS). The proposed TS changes would clarify the actions required in the event of inoperable equipment associated with the containment depressurization and cooling systems, and provide consistency between Unit 1 and Unit 2 requirements. TS 3/4.6.2.1, " Containment Spray System" and 3/4.6.2.3, " Containment Cooling System" would be combined into a single specification 3/4.6.2, " Containment Spray and Cooling Systems.
Fan cooler surveillance requirements would also be affected to the extent that the 31-day surveillance intervals need not be established on a " staggered test basis."
2.0 DISCUSSION AND EVALUATION 2.1 ST. LUCIE CONTAINMENT HEAT REMOVAL SYSTEMS The safety design requirement for containment heat removal equipment is to be able to cool and depressurize the containment to 50% of its peak accident pressure within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> after a DBA and maintain the containment at that pressure or less for a 30-day period. This function is provided by the Containment Spray System and the Containment Cooling System. These systems are required for mitigation of a Design Basis Accident and are thus classified as Engineered Safety Features. During normal plant operation, the Containment Cooling System serves to maintain the containment temperature below 120 deg.F.
The Containment Spray System is not used during normal operation.
2.1.1 CONTAINMENT SPRAY SYSTEM The function of the Containment Spray System is to provide containment heat removal and iodine removal during accident conditions.
It accomplishes its function through the use of two redundant spray trains.
Each train consists of a pump, chemical eductor, shutdown heat exchanger, piping, valves, and a spray header having four nozzle rings and a minimum of 178 nozzles. On a containment spray initiation signal (CSIS) the system is initiated with the pumps taking suction from the Refueling Water Tank (RWT).
On a recirculation actuation signal (RAS), pump suction is automatically switched to the containment sump. An RAS is generated when the RWT reaches low level. A Spray Additive System provides Na0H solution to the containment spray fluid via the eductor to ensure a post-accident pH value in the sump between 8.5 and 11.0.
This pH band minimizes the evolution of iodine and the corrosive effects of chieride.
Cooling water for the heat exchanger is from the Component Cooling Water System.
Each train of the Containment Spray System is capable of providing 50% of the post accident heat removal requirements and (if the non-redundant chemical addition system is operable) 100% of the iodine removal requirements.
9703170007 970301 PDR F01A BINDER 96-485 PDR
b.
- 2.1.2 CONTAINMENT COOLING SYSTEM The Containment Cooling System consist of four fan coolers that discharge via back draft campers into ducts which lead to a ring header. The cooled air is discharged from the ring header via registers and air outlets to the containment atmosphere in a manner designed to prevent stratification. During normal operation, three fan coolers are in use with the fans operating at high speed. Cooling water for the fan coil units is from the Component Cooling Water System. The fan coolers are arranged in two trains. Each train of two fan coolers is capable of providing 50% of the post-DBA heat removal requirement.
2.2 PROPOSED TS CHANGES 4
2.2.1 ALLOWABLE OUTAGE TIME CHANGES There are seven degraded conditions for which TS allowable outage times (A0Ts) would be affected. The table (Page 4) summarizes the proposed changes for each degraded condition.
The staff evaluated the proposed A0T changes against the criteria of the NUREG-1432 Standard Technical Specifications (STS). The STS A0Ts are based on the systems being designed to the following generic criteria; (a) each spray train is capable of meeting 50% of the total heat removal design requirement and 100% of the iodine removal design requirement, (b) each fan cooler train is capable of meeting 50% of the total heat removal design requirement and (c) one spray train is capable of iodine removal in accordance with radiological dose consequences analytical calculations. The licensee's application states that each St. Lucie fan cooler train is capable of satisfying at least 50% of accident heat removal requirements, and that each train of containment spray can satisfy 100% of the iodine removal requirements and 50% of accident heat removal requirements. The design of the St. Lucie containment heat removal systems are thus consistent with the design requirements upon which the generic STS operability requirements are predicated. Based on the systems descriptions pmvided in the FSARs, the plant-specific equipment is cimilar to that presumed for the generic STS (i.e., number of pumps, valves, fancoil units, heat exchangers, support systems, etc.). Accordingly, the generic STS completion times where proposed, are acceptable for St. Lucie. The STS criteria generally provide a 72-hour A0T for degraded ESF functions for conditions where operable capacity has degraded from 200% to 100%, and 7 days for conditions where operable capacity has degraded from 200% to 150%.
A discussion of each affected A0T is provided below. Note: " CONDITION" refers to row position in the table.
CONDITION 1, ONE SPRAY TRAIN INOPERABLE (ALL FAN COOLERS OPERABLE),
Pm 21750 PSIA The licensee proposes to bring the A0Ts into consistency for the two units.
The new A0Ts would be consistent with STS except that 54 hours6.25e-4 days <br />0.015 hours <br />8.928571e-5 weeks <br />2.0547e-5 months <br /> would be t
allowed between Mode 3 and Mode 4.
The STS specify 84 hours9.722222e-4 days <br />0.0233 hours <br />1.388889e-4 weeks <br />3.1962e-5 months <br /> from Mode 3 to Mode 5.
However, since the St Lucie facilities do not need chemical additive
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< spray to mitigate a DBA in Mode 4, a less restrictive 54 hour6.25e-4 days <br />0.015 hours <br />8.928571e-5 weeks <br />2.0547e-5 months <br /> action to be in Mode 4 is acceptable.
CONDITION 2, ONE SPRAY TRAIN INOPERABLE AND ONE FAN COOLER IN0PERABLE, Pen 2 1750 PSIA The A0T for this condition would be relaxed to appropriately reflect the capacity and redundancy (100% for both cooling and fission product removal) provided by the multiple trains of heat removal equipment that remain operable. The proposed A0T conforms to the STS requirements. As noted above, the STS criteria are appropriate for St. Lucie.
i CONDITION 3, ONE FAN COOLER INOPERABLE, P 2 1750 PSIA p3 The differing A0Ts for each unit would be brought into consistency with the STS. As noted above, the STS criteria are appropriate for St. Lucie.
CONDITION 4, BOTH TRAINS OF FAN COOLERS INOPERABLE (SPRAY OPERABLE),
Ppa 2 1750 PSIA The A0T would be revised to appropriately reflect the heat and fission product removal capability of the remaining operable spray systems (100% for both cooling and fission product removal). The change is consistent with the STS.
l As noted above, the STS criteria are appropriate for St. Lucie.
CONDITION 5, TWO FAN COOLERS IN0PERABLE IN THE SAME TRAIN, P, 21750 PSIA pz The A0Ts for this condition would be relaxed to appropriately reflect the heat removal capability of the remaining operable equipment (150% for containment cooling and 200% for fission product removal). The proposed A0Ts are the same as for condition 3 reflecting the fact that both fan coolers in a train must be operable for the train to be operable. The change is consistent with the STS and is appropriate for St Lucie.
CONDITION 6, ONE FAN COOLER IN0PERABLE, Pp3 < 1750 PSIA The proposed change provides an appropriate A0T for a condition in which fission product removal capability is not required and the spray systems will be unavailable.
CONDITION 7, TWO FAN COOLERS INOPERABLE IN THE SAME TRAIN, P,3 < 1750 PSIA The proposed A0T, as for condition 5 above, would appropriately reflect the heat removal capability of the remaining operable train and the unavailabity of other means of containment heat removal.
2.2.2 SURVEILLANCE REQUIREMENTS FOR FAN COOLERS TS 4.6.2.3 specifies that the fan coolers be tested at 31-day intervals on a
" staggered test basis." This means that the 31-day test interval is divided into four equal subintervals with one cooler tested at the beginning of each subinterval. The reason for staggered testing is to increase the rapidity of
. detection of common mode failures. The proposed change would eliminate the stagger feature.
The staff examined the LER records for the St. Lucie facilities to determine if continued staggered testing was warranted by past operating history. Of interest were (a) an LER which reported two fan coolers inoperable based on low CCW water flow due to low flow alarm settings (LER 91-004 for Unit 2), and (b) an LER reporting failure of a fan cooler to start due to dirty breaker contacts (LER 83-008 for Unit 1). Upon full review of the LERs, the staff determined that the staggered test requirement was not a factor in the timing of the discovery of the reported failures. Due to the fan coolers having flow alarms, staggered testing is of minor if any benefit. Since the fan coolers are served by a closed cooling water system, no significant or rapid fouling is expected within the 31-day interval. Also, there are other routine actions such as weekly valve status checks and containment temperature monitoring, that provide additional assurance that fan coolers are operable.
Elimination of staggered testing is also consistent with the new STS which no longer specifies that fan cooler tests be on a staggered basis. A 31-day test interval for each cooler, independent of the schedules for testing of other coolers, is acceptable.
3.0 CONCLUSION
i The licensee has proposed TS changes which (a) provide a significant improvement is consistency and format and (b) ensure the availability of sufficient containment heat and fission product removal equipment consistent with the generic staff positions relating to the reliability of these systems.
The proposed changes are therefore acceptable.
Principal Contributor:
W. Long, NRR/DSSA/SCSB 1
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APPLICA8!LITY AFFECTED CURRENT ACTION REQUIREMENT PROPOSED ACil0N REQUIREMENT N hTION
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i MODE 1,
- 1. ONE SPRAY UNIT 1 RESTORE IN0PERA8LE SPRAY TRAIN j
3 MODE 2 fRAIN TinWE 1 OR 2: RESTORE IMOPERABLE WITHIN 72 HOURS AND WITHIN 10 i
AND MODE 3 IMOPERASLE (ALL SPRAY ADDITIVE SYSTEM WITHIN 72 DAYS FROM INITIAL DISCOVERY OF WITH FOUR FAN HOURS OR BE IN MODE 3 WITHIN THE FAILURE TO MEET THE LCO OR BE IN PRESSURIZER COOLERS NEXT 6 NOURS -
MODE 3 WITHIN THE NEXT 6 NOURS PRESSURE 2 OPERA 8LE)
IN MODE 3: RESTORE SPRAY ADolTIVE AND MODE 4 WITHIN THE FOLLOWING 1750 PSIA SYSTEM WITHIN THE NEXT 48 NOUR$ OR 54 HOURS BE IN MODE 4 WITHIN THE FOLLOWING '
30 NOURS.
E 1 OR 2: RESTORE INOPERABLE SPRAY SYSTEM WITHIN 72 NOURS OR BE IN AT LEAST MODE 3 WITHIN THE NEXT 6 NOUR$;3:
IN MtBE RESTORE THE INOPERABLE SPRAY SYSTEM WITHIN THE NEXT 48 NOURS OR BE IN MtBE 4 WITMIN THE Fatttu!No 30 Nom s.
- 2. ONE SPRAY RESTORE EITNER THE INOPERABLE RESTORE THE FAN COOLER TRAIN TRAIN SPRAY TRAIN OR INOPERABLE FAN WITHIN 7 DAYS AND WITHIN 10 DAYS IN0PERA8tE AND COOLER WITHIN 72 NOURS OR BE IN OF DISCOVERY OF FAILURE TO MEET ONE FAN COOLER MOT SHUTDOWN WITHIN THE NEXT 12 rIE LCO AND th0PERABLE HOURS
' CcSTORE,THE SPRAY TRAIN WITHIN 72 MURS AND WITHIN 10 DAYS FROM DISCOVERY OF INITIAL FAILURE TO MEET THE LCO EACH OF THE A80VE ACTIONS IS TO BE SEPARATELY TRACXED FROM TIME OF DISCOVERY
- 3. ONE FAN T
RESTORE FAN COOLER TRAIN TO I
COOLER E THE FAN COOLER WITHIN 30 OPERA 81LITY WITHIN 7 DAYS AND lh0PERASLE DAYS OR SE IN MODE 4 WITHIN THE WITNIN 10 DAYS FROM INITIAL (BOTH SPRAY NEXT 12 NOURS DISCOVERY OF FAILURE TO MEET THE TRAINS T
LCO OR BE IN MIME 3 WITMIN THE OPERABLE)
E 1 OR 2: RESTORE THE FAN NEXT 6 NOURS AND IN MODE 4 WITHIN
)
COOLER WITHIN 72 MOURS OR SE IN THE FOLLOWING 6 MOURS MODE 3 WITHIN THE NEXT 6 HOURS IN IN2E 3: RESTORE THE FAN COOLER WITHIN THE NEXT 48 NOURS OR BE IN MODE 4 WITHIN THE FOLLOWING 30 HOURS.
- 4. SOTH TRAINS ENTER LCO 3.0.3 RESTORE ONE TRAIN WITH!N 72 HOURS OF FAN COOLERS OR BE IN MODE 3 WITHIN THE NEXT 6 INOPERABLE HOURS AND MODE 4 WITHIN THE (SOTH TRAINS OF FOLLOWING 6 NOUR$
CONTAlifENT SPRAY (P58Ami p g
- 5. TWO FAN ENTER LCO 3.0.3 RESTORE FAN COOLER TRAIN TO COOLERS OPERASILITY WITHIN 7 DAYS AND INOPERABLE IN WITHIN 10 DAYS FROM INITIAL THE SAFE FAN DISCOVERY OF FAILURE TO MEET THE 9
COOLER TRAIN LCO OR BE IN MODE 3 WITHIN THE i
(50TM SPRAY hEXT 6 NOURS AND IN MODE 4 WITHIN TRAINS THE FOLLOWING 6 NOUR$
MODE 3 WITH
- 6. ONE FAN IT 1 RESTORE THE INOPERABLE FAN COOLER PRESSUR12ER COOLER E IN0PERA8LE FAN COOLER TRAIN WITNIN 72 NOURS OR BE IN PRESSURE <
INOPERABLE WITHIN 30 DAYS OR BE IN NOT MODE 4 WITHIN THE NEXT 6 NOURS 1750 PSIA SMUTDOWN WITHIN THE NEXT 12 NOURS (NOTE: SPRAY T
SYSTEMS ARE E 1 OR 2: RESTORE INCPERABLE DEACTIVATED IN FAN COOLER WITNIN 72 NOURS OR BE THIS IN AT LEAST NOT STANDeY WITHIN TEf CONDITION)
NEXT 6 NOURS; IN MODE 3: RESTORE THE INOPERASLE FAN COOLER WITHIN THE NLXT 68 MOURS OR SE IN COLD
$NUTDOWN WITMIN THE FOLLOWING 30 NOURS.
- 7. TWO FAN _
ENTER 3.0.3 RESTORE THE INOPERASLE FAN COOLER COOLERS TRAIN WITHIN 72 NOURS OR BE IN INOPERASLE IN MODE 4 WITNIN THE NEXT 6 MOURS THE SAFE FAN COOLER TRAIN