ML20209A726
| ML20209A726 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 04/23/1987 |
| From: | SACRAMENTO MUNICIPAL UTILITY DISTRICT |
| To: | |
| Shared Package | |
| ML20209A710 | List: |
| References | |
| TAC-65196, NUDOCS 8704280265 | |
| Download: ML20209A726 (15) | |
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ATTACHMENT I RANCHO SECO TECHNICAL SPECIFICATIONS (Pages affected by Proposed Amendment No. 154.)
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B704280265 B70423 PDR ADOCK 05000312 ,
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RANCHO SECO UNIT 1 TECHNICAL SPECIFICATIONS ,
Limiting Conditions for Operation 3.2.2 The Low Tenperature Overpressure Protection Systen will require the following conditions:
I 3.2.2.1 LTOP will be manually enabled prior to the Reactor coolant i
system temperature dropping below 350'F during plant cooldown.
j ' 154> 3.2.2.1.1 Hanual enabling of LTOP shall be accomplished by placing
- the Key Select Switch for the EH0V to the " Low" position
<. and by placing HV-21505 in the "Open" position.
3.2.2.2 All HPI Systems will be locked out whenever the RCS tenperature is below 350*F. This shall be done by opening and tagging the circuit breakers for the four HPI
' Motor-Operated Yalves (Loop A: SFY-23809, SFV-23811; and Loop B: HV 23801, SFV-23812) with the valves in the closed
. 154>< position, except as specified below:
154> 3.2.2.2.1 During Makeup, Letdown and Purification System 4 startup, any of the four HPI MOVs specified in 3.2.2.2 above, which are performing the required isolation function, nay be individually opened as required to fill and vent the respective injection line subject to the conditions stated in 3.2.2.2.2 and 3.2.2.2.3 below:
3.2.2.2.2 All HPI-Makeup pump breakers shall be racked out and tagged during the filling and venting specified in 3.2.2.2.1. .
3.2.2.2.3 Only one of the four HPI MOVs specified in 3.2.2.2 above may be open at any one time, and it shall be closed and its breaker racked out and tagged upon conpletion of its line's filling and venting 3.2.2.3 The nakeup tank water level is to be less than 86 inches.
3.2.2.4 The pressurizer water level will be maintained at or-below 220 inches at systen pressures above 100 psig and less than 275 inches for pressures less than or equal to 100 psig except during RCS filling and draining.
3.2.2.5 When the RCS tenperature is below 350'F, the core flood tank discharge valves are closed and the circuit breakers _ '
for the motor operators are racked out before the RCS
. 154> pressure is decreased to 600 psig, except as specified
< below:
Proposed Amendment No. 154
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RANCHO SECO UNIT 1 TECHNICAL SPECIFICATIONS Liuiting Conditions for Operation 154> 3.2.2.5.1 When the Core Flood Tank pressure is below 500 psig, the discharge valves shall be allowed to remain open
< or be opened.
3.2.2.6 When LTOP is required, only one HPI pump will be operated except during the transition of pumps that will supply Reactor Coolant Pump seals and makeup flow for the RCS.
Bases The makeup and purification system and chemical addition s{ stems provide control of the reactor coolant system boron concentration. This is nonaally accomplished by using either the makeup pump or one of the two high pressure injection pumps in series with a boric acid pump associated with the concentrated boric acid storage tank. The alternate method of boration will be the use of the makeup or high pressure injgetion pumps taking suction directly from the borated water storage tank.'
The quantity of boric acid in storage from either of the two above-mentioned sources is sufficient to borate the reactor coolant systen to a 1 percent subcritical margin in the cold condition (70F) at the worst time in core life with a stuck control rod assembly. The maximum required is the equivalent of 9586 gallons of 7100 ppm boron. This requirement is satisfied by requiring a minimum volume of 10,000 gallons of 7100 ppm in the concentrated borated acid storage tank during critical operations. The minimum volume for the borated water storage tank (390,000 gallons of 1800 ppm boron), as specified in section 3.3, is based on refueling volume requirements and easily satisfies the cold shutdown requirement. The specification assures that the two supplies are available whenever the reactor is critical so that a single failutt. will not prevent boration to a cold condition. The minimum volumes of boric acid solution given include the boron necessary to account for xenon decay.
The primary method of adding boron to the primary system is to pump the concentrated boric acid solution (7100 ppm boron, minimum) into the makeup tank using the 50 gpm boric acid pumps. Using only one of the two boric acid pumps, the required volume of boric acid can be injected in less than 3.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />. The alternate method of addition is to inject boric acid from the borated water storage tank using the high pressure injection pumps.
Proposed Amendment No. 154 3-18
RANCHO SECO UNIT 1 TECHNICAL SPECIFICATIONS Limiting Conditions for Operation Bases (Continued)
Concentration of boron in the concentrated boric acid storage tank may be higher than the concentration which would crystallize at ambient conditions.
For this reason and to ensure that a flow of boric acid is available when needed, this tank and its associated piping will be kept above 70F (30F above the crystallization temperature for the concentration present). Once in the high pressure injection system, the concentrate is sufficiently well mixed and diluted so that nomal system temperatures ensure boric acid solubility.
The value of 70F is significantly above the crystallization temperature for a 154>< solution containing 12,200 ppa boron.3 The Low Temperature Overpressure Protection System (LTOP) consists of both an active and a passive subsystem. The active subsystem utilizes the Electro Matic Operated Valve (EH0V) which provides overpressure protection during normal plant operation. The EMOV actuation circuitry has been modified to low-temperature provide opera a second tions. The low setpoint setpoint(500 psig) that is manually is used enabled during'F by positioning a at 350 key-operated switch in the Reactor control Room. An alarm will sound in the Reactor Control Room if the reactor coolant pressure falls below 450 psig and the key-operated switch is not selected for low-temperature operation. After selection of low temperature operation, additional alarms will occur if either HPI pump breaker is not racked out; if either Seal Injection flow is greater than 42 gpa or makeup flow is greater than 135 gpu; if HPI valves are not closed; and if the EH0V block valve HV-21505 is not open. The passive subsystem is based on the plant design and operating philosophy that precludes the plant from being in a water solid condition (except for system hydrotests) .
154> Injection line filling and venting is accomplished without an energized Makeup or High Pressure Injection pump. Nitrogen overpressure in the Makeup tank provides the motive force for fluid flow during this evolution. This nitrogen overpressure is limited procedurally to 30 psig, and mechanically to 100 psig by the relief valve on the Makeup tank. This pressure clearly does not approach the EMOV low setpoint.
The exception to core flood discharge valves being closed and their motor operator deenergized is based on the Core Flood Tank pressure being reduced to less than the EMOV low setpoint of 500 psig. Without the potential for RCS overpressurization, the valve need not be administratively required to be closed. This provides for other surveillance testing and maintenance on the
< Core Flood System.
Proposed Amendment No. 154 3-18a
RANCHO SECO UNIT 1 TECHNICAL SPECIFICATIONS Limiting Conditions for Operation The Rancho Seco Reactor Coolant system always operates with a steam or gas space in the pressurizer; the steam bubble is replaced with nitrogen during plant cooldown when systen pressure is reduced. The requirements for a maximum pressurizer level provides for a sufficient vapor. space in the pressurizer to retard the rate of increase of RCS pressure, as compared to a water solid system for all mass and heat input transients. In this manner, the. operator will have time to recognize that a pressure transient is in progress and take action to mitigate the incident. For these reasons the pressurizer water level will be maintained at.or below 220 inches at systen pressures above 100 psig and less than 275 inches for systen pressures less than or equal to 100 psig. The only exception to these requirements will be when the RCS is being filled or drained. During the filling process the pressurizer is filled with water up to the 320 inch level. The High Point Vents are opened and nitrogen is injected into the pressurizer hence forcing the coolant into the loops. Subsequently, the High Point Vents are closed, a 4
steam bubble is drawn and the nitrogen is released through the pressurizer vents. During the draining process, the pressurizer is depressurized, the High Point Vents and RCS Hot Leg Vents are opened thus reducing the RCS to atmospheric pressure. The loop coolant level and pressurizer level equalize at 320 inches and draining can then take place.
In conjunction with the enablement of LTOP at 350*F and the subsequent restriction on. pressurizer level, analysis has shown that the HPI system is not needed when RCS temperature ? alls below 350*F. The requirement for a aaximua makeup tank level limits the mass input available from the tank should the makeup valve fail open.
When LTOP conditions are required, only one of the two HPI pumps or the makeup pump will be allowed to operate. Rancho Seco normally operates with the makeup pump supplying makeup and seal injection. Should, in the unlikely event, degradation of this pump occur while in the LTOP mode, it would be necessary to start one of the HPI pumps before stopping the makeup pump.
This scenario would result in a brief overlap time period where an increase in flow through the makeup line would occur. However, because the operator is aware of the LTOP conditions, it is expected that this brief transition-stage would no.t significantly increase the level of the pressurizer and the probability of an over-pressurization incident.
Proposed Amendment No. 154 154>< 3-18b
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RANCHO SECO UNIT 1 TECHNICAL SPECIFICATIONS Limiting Conditions for Operation Separate power supplies are provided for the EMOV circuitry and LTOP alanas which alert the operator of an overpressurization event so that a single power source failure will not disable the EMOV and LTOP alarms. This assures the operator is alerted so he can take action to terminate an event even if the EMOV is disabled. These alarms are high pressurizer level, high - high pressurizer level, and high makeup tank water level.
REFERENCES 1 FSAR Subsections 9.2 and 9.3 2 FSAR Figure 6.2-1 3 Technical Specification 3.3 Proposed Amendment No. 154 154>< 3-18c
RANCHO SECO UNIT 1 TECHNICAL SPECIFICATIONS Surveillance Standards ,
4.31 NUCLEAR SERVICE ELECTRICAL BUILDING EMERGENCY HEATING VENTILATION AND AIR CONDITIONING Applicability Applies to the Nuclear Service Electrical Building (NSEB) Heating Ventilation and Air Conditioning (HVAC) System components.
Objective To verify that this system and its components will be able to perfom their design functions.
Specification 4.31.1 The NSEB Emergency HVAC shall be:
A. Demonstrated operable at least once per 31 days by initiating flow through the essential air handling unit.
154> 1. Verify that the air handling unit maintains a minimum flow
< rate of 24,500 cfa.
- 2. Verify that the condensing unit is operational.
Bases The purpose of the Emergency Nuclear Service Electrical Building HVAC is to limit high temperatures which the building would be subjected to upon loss of normal cooling. The high temperatures will affect the environmental qualification of safety related electronic equipment housed within the NSEB which is used to support the Control Room /TSC upon accident conditions. The system is designed with an air handling unit and a condensing unit which are activated upon high temperature signals.
Since this system is not normally operated, a periodic test is required to ensure its operability when needed. Monthly testing of this system will show that the system is available for its safety action. During this test the system will be observed for unusual or excessive noise or vibration when the 154>< fan motors are running. The minimum air flow of 24,500 cfm was selected to limit the temperatures in the building to 80*F maximum (with the exception of the cable shafts).
4 The system is automatically started when the temperature in the NSEB Switchgear Room exceeds 95 F, except upon loss of offsite power; in which case, the system can be manually started by the operator.
Proposed Amendment No. 154 4-91
ATTACHMENT II PROPOSED AMENDMENT FACILITY CHANGE PAGE 1 0F 6 PROPOSED AMENDMENT NO. 154 DESCRIPTION:
Proposed Amendment #154 provides for venting and surveillance testing of the Low Temperature Overpressure Protection (UTOP) system. The Ur0P system is addressed in section 3.2.2 of technical specifications.
This technical specification amendment provides more detail about valve positioning requirements: 1) when Ur0P is enabled, 2) when venting of the Makeup and Purification system is performed, and 3) when surveillance of core flood tank is performed. This includes valves associated with the EMOV, Makeup and Purification system, and the core flood tank.
Finally, the amendment specifies a minimum flow rate on the NSEB Emergency HVAC air handling unit.
REASON FOR CHANGE:
Purpose Technical Specification Amendment #82 (8/13/86) incorporated the Low Temperature Overpressure Protection (UTOP) system into the technical specifications. Subsequent to Amendment No. 82, reviews have determined that the specification needs to provide for venting and surveillance testing while in LTOP condition. This proposed amendment addresses these areas. Finally, this amendment ensures that the surveillance standards for the NSEB HVAC unit agree with technical specification bases for system performance.
EVALUATION AND BASIS FOR SAFETY FLNDINGS:
Systems, subsystems, Components Affected Proposed Amendment 154 deals with the Low Temperature Overpressure Protection (UTOP) system. As part of the LTOP system interfaces, this amendment affects the reactor coolant system, the high pressure injection system and the core flood system. Additionally, the amendment places a minimum flow requirement on the NSEB Emergency HVAC system.
Safety Functions of Af fected Systems / Components l
10CFR50, Appendix G sets forth fracture toughness requirements applicable to ferritic materials of pressuce-retaining components of the reactor coolant pressure boundary. These requirements are most restrictive at lower temperatures. The LTOP system was installed to reduce the likelihood and consequences of an overpressure event at low temperatures (less than 3500F).
ATTACIDENT II (CONT.)
e PROPOSED AMENDMENT FACILITY CHANGE PAGE 2 0F 6 PROPOSED AMENDMENT NO. 154 i
Safety Functions of Affected Systems / Components (Cont.)
i The Low Temperature Overpressure Protection System (Technical Specification Section 3.2.2) consists of both an active and a passive subsystem. The active subsystem uses the EMOV, which, through the modification of its circuitry, has a second setpoint (500 psig) which is used during low-temperature operations.
- This second setpoint is manually enabled at 3500F. The passive subsystem is based on the plant design and operating philosophy that. precludes the plant from being in a solid condition. (The Rancho Seco RCS always operates with a steam or nitrogen space in the pressurizer. The limits for maximum pressurizer level provides enough space in the pressurizer to retard the rate of increase of RCS pressure compared to a solid system for all analyzed mass and heat input transients.)
The reactor coolant system pressurizer establishes and maintains the reactor coolant system pressure within prescribed limits and provides a steam surge chamber and a water reserve to accommodate reactor coolant density changea l during operation (USAR Section 4.2.2.3). Since all sources of heat in the
! system, core, pressurizer heaters, and reactor coolant pumps are interconnected by the reactor coolant piping, relief protection is provided on the pressurizer. Overpressure protection consists of two code safety valves i and one electromagnetic relief valve.
I The high pressure injection system, low pressure injection system, and core flood system provide full protection across the entire spectrum of reactor coolant system break sizes. Each may operate individually and each is initiated independently. The high pressure injection system (USAR Section 6.2) prevents uncovering of the core during small coolant piping leaks, where high reactor coolant system pressure is' maintained, and delays uncovering of the core during intermediate-sized leaks. High pressure. injection of borated water, provided by the makeup and purification system, is initiated by low reactor coolant system pressure or high reactor building pressure. Automatic 4
actuation switches the HPI system (part of the Makeup and Purification system)
- from.its normal operating mode to the emergency mode to deliver water from the
! borated water storage tank into the reactor vessel through the reactor coolant
! lines.
. The core flooding system provides core protection continuity for intermediate !
, and large reactor coolant system pipe failures (USAR Section 6.2.2.1.3). It !
! automatically floods the core when reactor coolant system pressure drops below l j 600 psig. The core flood system is passive, and requires no operator or '
control action to actuate. The combined volume in the two core flood tanks is sufficient to cover the core to the 3/4 point, assuming no liquid remains in the reactor vessel following a loss-of-coolant accident. Each core flood line at the outlet of the CFTs contains an electric motor-operated stop valve adjacent to the tank and two in-line check valves in series. The stop valves i
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ATTACIDENT II (CONT.)
PROPOSED AMENDBENT FACILITY CHANGE PAGE 3 0F 6 PROPOSED AMENDMENT No. 154 Safety Functions of Affected Systems / Components (Cont.)
at the tank outlet are open (and their respective breakers open) before bringing the reactor to criticality. During power operation when the reactor coolant system pressure is higher than the core flooding system, the two check valves prevent high-pressure reactor coolant from entering the core flooding tanks.
The Nuclear Service Electrical Building (NSEB) houses nuclear service
, batteries, switchgear, battery chargers, and the necessary electrical equipment required to support the TSC, control room, and the HVAC system (USAR
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Section 5.5.5). The NSEB is served by normal and essential (backup)
- ventilation systems (USAR Section 9.7.3.1.G). The normal system consists of two air conditioning units, two normal return exhaust fans, two ventilators, j and one unit heater. The essential system is made up of two condensing units
! and two direct expansion coils with supply fan. The minimum design capacity of the NSEB essential HVAC fan is 24,500 cfa.
Effects on Safety Functions The LTOP system uses the Electro Matic Operated Valve (EMOV) to provide overpressure protection. The EMOV actuation circuitry was modified to provide a 500 psig setroint to be used during low temperature operation. The low i setpoint is manually enabled at an RCS temperature of 3500F by means of a key-operated switch in the control room. An alarm sounds in the control room ,
if reactor coolant pressure falls to less than 450 psig and the key-operated j switch (for selecting the low-pressure setpoint) is not selected for i icv-temperature operation. One of the technical specification Amendment 154 4
changes provides specific direction to the operator for " enabling" the LTOP key-select switch and for ensuring that HV-21505, the EMOV block valve is open. This change formalizes the requirements for what is currently an l operational, procedural action (the valve is opened / verified open in procedure l B.4, Shutdown and Cooldown); therefore, no new failure mode is introduced and-there is no effect on any safety ' function.
A second change to technical specifications is the provision for filling and venting the Makeup and Purification system during system startup. This change permits the opening of specific, individual, HPI MOVs that were closed for LTOP in the previous technical specification subsection. Venting of the injection lines is only performed without an energized Makeup or HPI pump; HPI and Makeup pump breakers are racked out at this time. Nitrogen pressure in the Makeup tank provides the motive force. This pressure is procedurally limited to 30 psig and mechanically limited (by the Makeup tank relief valve) to 100 psig. This change only' allows operation of one valve at a time, with closure of the valve, and racking out of that valve's breaker, when the evolution is completed; therefore, no new failure mode is introduced and there is no effect on any safety function.
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l ATTACIDelT II (CONT.)
j l' PROPOSED AMENDlWIT FACILITY CHANGE PAGE 4 0F 6 4 PROPOSED AMENDMENT No. 154 Effects on Safety Functions (Cont.)
Additionally, this amendment provides for the surveillance testing of the core flood tank. The Core Flood Tank discharge valves shall be allowed to remain open or be opened if Core Flood Tank pressure is maintained below the EMOV
" low" setpoint of 500 psig. The nitrogen supply and water supply valves to i the Core Flood Tanks are locked closed, per Procedure A.4, Core Flooding '
i System. Repressurization of the Core Flood Tank is a procedurally-controlled evolution involving unlocking the necessary supply valves. Without the i potential for RCS overpressurization, the valves need not be administrative 1y required to be closed. This permits both surveillance testing and maintenance on the Core Flood Tanks. There is no effect on the safety function of the
- core flood tanks.
The final change to be incorporated is the requirement for the NSEB Emergency-HVAC air handling unit to maintain the minimum flow rate of 24,500 cfa. This air flow rate was selected to limit the temperatures in the NSEB building to 800F maximum. Air flow is verified once per 31 days by initiating flow l through the essential air handling unit. This Amendment changes the tolerance on the unit by eliminating the + condition and requiring a minimum flow rate of 24,500 cfm as specified in technical specification bases. A higher flow rate will enhance the capability of the system to maintain the designed temperature in the NSEB. Any noise resulting from higher flow rates is not a
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factor since this is not a normally occupied area. Therefore, this change has no effect on the safety function of the NSEB air handling' unit.
j Analysis of Effects on Safety Functions 3
In August of 1976, the NRC requested SMUD to evaluate the susceptibility of the facility to overpressurization events and to propose modifications to systems and procedures to reduce the likelihood and consequences of such events. This request was the result of significant pressure transients that
- had occurred during cold shutdown conditions at other operating reactors. The incidents occurred at low temperatures, where reactor vessel material toughness is reduced from that which exists at normal operating temperatures.
An NRC letter dated June 29, 1984, Safety Evaluation for low Temperature Overpressure Protection, mandated that several administrative controls be ,
- added to Rancho Seco Technical Specifications. These controls were to prevent t or reduce the likelihood of a Low Temperature Overpressure incident. These controls were made a part of technical specifications as Amendment 82. They were also formalized with the revision of Plant Operating Procedures B.2, Plant Heatup, and B.4, Plant Shutdown and Cooldown.
, Subsequent to the incorporation of Amendment 82 into technical specifications, reviews determined that the technical specifications needed provisions for fill and vent-and surveillance testing. The changes for Amendment 154 provide additional information for the requirements established by Amendment 82.
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ATTACHMENT II (CONT.)
PROPOSED AMENDMENT FACILITY CHANGE PAGE 5 0F 6 PROPOSED AMENDMENT NO. 154 Analysis of Effects on Safety Functions (Cont.)
EMOV block valve HV-21505, will be normally open during power operationa. As a result of Amendment 154, this valve is verified opened and the EMOV setpoint pressure is reset to " low" (500 psig) when the RCS is less than or equal to 350 degrees F when LTOP is enabled during shutdown.
Technical Specifications Section 3.2.2.2 lists valves which must be cloced in order to isolate the HPI system from the RCS. Amendment 154 provides for the manipulation of specific, individual valves to fill and vent the Makeup and Purification system during system startup. The valves must be operated one valve at a time and the valves must be reclosed after system fill and vent is completed. The motive force for this fill and vent is the 30 psig nitrogen head in the Makeup tank. By maintaining low system pressures (100 psig maximum), and the fact that the HPI and Makeup pump breakers are racked out during this fill and vent evaluation, the intent of LTOP continues to be met.
The Core Flood Tank discharge valves may remain open if Core Flood Tank pressure remains below the EMOV setpoint of 500 psig. This permits both surveillance testing and maintenance on the Core Flood Tank. With the pressure in the Core Flood Tanks less than 500 psig, the Core Flood Tanks no longer provide a source that can overpressurize the RCS. (The nitrogen supply and water supply valves to the CFTs are locked closed to prevent pressurization of the CFT, to greater than 500 psig.) Inadvertent operation of the Core Flood Tank would not result in RCS pressure that would actuate the EMOV at the low setpoint of 500 psig.
The proposed change to NSEB HVAC flow requirements changes the tolerance to a minimum required flow. This is a more conservative approach than curree:1y exists, which allows a 4900 cfm flow tolerance. This is consistent with the design criteria of the system which specified a minimum flow requirement to ensure adequate cooling.
The changes incorporated in Amendment 154 provide additional information on establishing LTOP conditions, provide for fill and vent of Makeup system during startup, or provide a method to perform a core flood tank surveillance. None of the changes introduces a new failure mode, and there are no effects on any safety functions.
Summary Proposed Amendment 154 consists of three LTOP-related changes to technical -
specifications, and one change related to the HVAC system in the Nuclear l Service Electrical Building. The changes include amplifying information on I valve positioning to enable LIOP, an allowance for testing of core flood system, as required in Technical Specification Section 4.5.1.1.C, and ,
provisions for fill and vent of the Makeup and Purification system. No new i failure modes are introduced as a result of these changes, and there are no effects on safety functions of any system.
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ATTAODENT II (CONT.)
PROPOSED AMENDMENT FACILITY CHANGE PAGE 6 0F 6 PROPOSED AMENDMENT NO. 154 Summary (Cont.)
The change to the NSEB HVAC surveillance standard more clearly specifies the required flow rate. It eliminates the tolerance in flow rates previously allowed, and states a minimum flow rate which agrees with technical specification bases. This change has no effect on the safety function of the NSEB Emergency HVAC, and it does not introduce a new failure mode.
The proposed amendment does not change the facility as described in the USAR.
The proposed amendment does not increase the probability of occurrence or consequences of a previously evaluated accident since the valve manipulations are performed with pump breakers racked out, at low system pressures, meeting the intent of existing LTOP technical specification requirements.
The possibility of an accident of a different type than previously evaluated is not created since all valve manipulations are performed by procedure, with small differential pressures on the valves.
The proposed amendment does not reduce the margin of safety as defined in technical specification since the changes allow testing under procedural control and at system conditions that do not violate LTOP philosophy, and the intent of the existing LTOP technical specification requirements are met.
Therefore, an Unreviewed Safety Question is not involved.
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. ATTACHMENT III "N0 SIGNIFICANT HAZARDS" CONSIDERATION PAGE 1 0F 2 '
PROPOSED AMENDMENT N0. 154 Amendment No. 82, which incorporated the Low Temperature Overpressure Protection (LTOP) system into the Rancho Seco Technical Specifications, was issued by the NRC on August 13, 1986.
Subsequent to issuance of Amendment No. 82, it has become evident that the amendment is deficient in not providing for venting and surveillance testing of the LTOP system.
Proposed Amendment No. 154 is submitted to correct this deficiency and to change the flow rate requirement for the Nuclear Service Electrical Building (NSEB) HVAC air handling units from a specified value with a minimum / maximum tolerance to a minimum flow rate that limits the temperature in the NSEB to not more than 80 F.
The District has reviewed the proposed changes against each of the criteria of 10 CFR 50.92 and concluded that plant operation with (1) provisions for LTOP venting and surveillance testing and (2) maintaining a specified mini-mum flow through the NSEB HVAC air handling units would not constitute a significant hazard to the public. Following are the bases for this conclusion.
Proposed Amendment 154 consists of four LTOP-related changes to tech-nical specifications, and one change related to the HVAC system in the Nuclear Service Electrical Building. The changes include:
An addition to the applicability requirement for Section 3.2.2, which amplifies information on valve positioning to enable LT0P.
An allowance for testing of core flood systems, as required in Technical Specification Section 4.5.1.1.C.
Provisions for fill and vent of the Makeup and Puri-fication system.
No new failure modes are introduced as a result of these changes, and there are no effects on safety functicns of any system.
The change to the NSEB HVAC surveillance standard more clearly specifies the required flow rate. It eliminates the tolerance in flow rates pre-viously allowed, and states a minimum flow rate which agrees with tech-nical specification bases. This change has no effect on the safety function of the NSEB Emergency HVAC, and it does not introduce a new failure mode, involve any accident previously evaluated, nor reduce any margins of safety.
The proposed amendment does not change the facility as described in the USAR.
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4 PAGE 2 0F 2 The proposed amendment does not increase the probability of occurrence or consequences of a previously evaluated accident, because the valve manipulations are_ performed with pump breakers racked out, at low system pressures, and meet the intent of existing LTOP technical specification requirements.
The possibility of-an accident of a different type than previously evaluated is not created because all valve manipulations are performed by procedure, with small differential pressures on the valve.
The proposed amendment does not reduce the margin of safety as defined in technical specifications because the changes allow testing under procedural control with system conditions that do not violate LTOP philosophy. Thus, the intent of the existing LTOP technical specifi-cation requirements are met.
On the basis of the above considerations, the District concludes that the
- proposed changes do not constitute any significant hazards, and in no way i endanger-the health and safety of the public.
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