ML20077F074

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Proposed TS 3.7.B,Pages 152,153 & 154 Re Standby Gas Treatment Power Supply Requirements During Refueling Operations
ML20077F074
Person / Time
Site: Vermont Yankee Entergy icon.png
Issue date: 12/08/1994
From:
VERMONT YANKEE NUCLEAR POWER CORP.
To:
Shared Package
ML20077F069 List:
References
NUDOCS 9412130260
Download: ML20077F074 (5)
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Text

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VYNPS 3.7 LIMITING CONDITIONS FOR 4.7 SURVEILLANCE REQUIREMENTS-OPERATION AP is reduced to l <1,7) during

! required l

operability testing of the HPCI systtm pump, the RCIC system pump, the drywoll-suppression .

chamber vacuum breakers, and the supprecsion chamber-reactor building vacuum l- breakers, and SGTS testing.

d. If the specifications of 3.7.A.9.a cannot be met, and the differential pressure cannot be restored within the subsequent six (6) hour period, an orderly shutdown shall be initiated and the reactor shall be in a Hot Shutdown condition in six (6) hours and a Cold Shutdown condition in the following eighteen (18) hours.

B. Standby Gas Treatment System B. Standby Gas Treatment System l 1. a. Except as specified 1. At least once per in Specification operating cycle, not to 3.7.B.3.a below, exceed 18 months, the whenever the following conditions reactor is in Run shall be demonstrated.

Mode er Startup Mode, both circuits a. Pressure drop of the Standby Gas across the combined Treatment System HEPA and charcoal shall be operable filter banks is i at all times when less than 6 inches  !

secondary of water at containment 1500 cfm *10%.

integrity is 1 required. b. Inlet heater input is at least 9 kW-.

b. Except as specified in Specification 3.7.B.3.b below, ,

whenever the  !'

reactor is in Refuel Mode, both circuits of the Standby Gas Amendment No. M , 49, M 152 9412130260 941200 {

PDR ADOCK 05000271 P PDR

VYNPS 3s7 LIMITING CONDITIONS FOR 4.7 SURVEILLANCE REQUIREMENTS OPERATION Treatment System 2. a. The tests and and an auxiliary sample analysis of electrical power Specification source, consisting 3.7.B.2 shall be of the associated performed initially Emergency Diesel and at least once Generator or Vernon per operating cycle tie, for each not to exceed standby gas 18 months, and treatment circuit following painting, shall be operable fire or chemical at all times when release in any secondary ventilation zone containment communicating with integrity is the system, while required. the system is operating, that

2. a. The results of the could contaminate in-place cold DOP the HEPA filters or and halogenated charcoal adsorbers.

hydrocarbon tests at design flows on b. Cold DOP testing HEPA and charcoal shall be performed filter banks shall after each complete show 1 99% DOP or partial l removal and 199% replacement of the j halogenated HEPA filter bank.

hydrocarbon removal. c. Halogenated i hydrocarbon testing l

b. The results of shall be performed '

laboratory carbon after each complete sample analysis or partial shall show 195% replacement of the radioactive methyl charcoal filter iodide removal. bank.

(1300C, 95% RH).

Laboratory analysis In addition, the results shall be sample analysis of verified acceptable Specification within 31 days 3.7.B.2.b and the following sample halogenated removal or the hydrocarbon test applicable train of shall be performed the Standby Gas after every Treatment System 720 hours of normal [

shall be considered system operation.

in-operable and the requirements of d. Each circuit shall Specification be operated with 3.7.B.3 shall the heaters on at apply. least 10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br /> every month,

c. System fans shall be shown to operate e. An ultrasonic leak within 110% of test shall be design flow. performed on the gaskets sealing the housing panels downstream of the HEPA filters and adsorbers at least Amendment No. M, M 153

VYNPS 3g7 LIMITING CONDITIONS FOR 4.7 SURVEILLANCE REQUIREMENTS OPERATION l 3. a. From and after the once per operating date that one cycle not to exceed circuit of the 18 months. If the Standby Gas ultrasonic test Treatment System is indicates the made or found to be presence of a leak, inoperable for any the condition will reason, reactor be evaluated and operation is the gasket repaired permissible only or replaced as during the necessary.

succeeding seven days unless such f. DOP and halogenated circuit is sooner hydrocarbon test made operable, shall be performed provided that following any during such seven design modification days all active to the Standby Gas components of the Treatment System other standby gas housing that could treatment circuit have an effect on shall be operable. the filter officiency.

3. b. From and after the date that one g. An air distribution circuit of the test demonstrating Standby Gas uniformity within Treatment System is 120% across the made or found to be HEPA filters and inoperable for any charcoal adsorbers reason, operations shall be performed requiring secondary if the SGTS housing l containment are is modified such permissible only that air during the distribution could succeeding seven be affected.

days unless such circuit is sooner 3. a. At least once per made operable, operating cycle provided that automatic l during such seven initiation of each days all active branch of the components, Standby Gas l including the Treatment System l associated shall be i Emergency Diesel demonstrated. l Generator of the l other standby gas b. Operability testing l treatment circuit of valves shall be  !

shall be operable. in acccrdance with Specification

4. If this condition cannot 4.6.E.

be met, procedures shall be initiated immediately c. When one circuit of to establish the the Standby Gas conditions listed in Treatment System is Specifications made or found to be 3.7.C.1(a) through (d), inoperable, the and compliance shall be other circuit shall completed within have been or shall 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> thereafter. be demonstrated to be operable within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

Amendment No. M, 49, 444, MB 154

VYNPS BASES: 3.7 (Cont'd) l The Standby Gas Treatment System (SGTS) is designed to filter and exhaust the Reactor, Building atmosphere to the stack during secondary containment isolation conditions, with a minimum release of radioactive materials from the Reactor Building to the environs. To insure that the standby gas treatment system will be effective in-removing radioactive contaminates from the Reactor Building air, the system is tested periodically to meet the intent of ANSI N510-1975.

Both standby gas treatment fans are designed to automatically start upon containment isolation and to maintain the Reactor Building i pressure to approximately a negative 0.15 inch water gauge pressure; all leakage should be in-leakage. Should the fan fail to start, the redundant alternate fan and filter system is designed to start automatically. Each of the two fans has 100% capacity. This substantiates the availability of the operable circuit and results in no added risk; thus, reactor operation or refueling operation can continue. If neither circuit is operable, the plant is brought to a condition where the system is not required.

When the reactor is in cold shutdown or refueling the drywell may be open and the Reactor Building becomes the only containment system.

During cold shutdown the probability and consequences of a DBA LOCA are substantially reduced due to the pressure and temperature limitations in this mode. However, for other situations under which significant radioactive release can be postulated, such as during operations with a potential for draining the reactor vessel, during l core alterations, or during movement of irradiated fuel in the secondary containment, operability of standby gas treatment is required. An auxiliary electrical power source for the purposes of Specification 3.7.B.1.b shall consist of either an Emergency Diosel Generator (EDG) or the Vernon Hydro tie line. Maintaining availability of the Vernon Hydro tie line as an alternative to one of the EDGs in this condition provides assurance that standby gas treatment can, if required, be operated without placing undue constraints on EDG maintenance availability. Inoperability of both I circuits of the SGTS or both EDGs during refueling operations I requires suspension of activities that represent a potential for i releasing radioactive material to the secondary containment, thus placing the plant in a condition that minimizes risk.

Use of the SGTS, without the fan and the 9 kW heater in operation, as a vent path during torus venting does not impact subsequent adsorber capability because of the very low flows and because humidity control is maintained by the standby 1 kW heaters, therefore operation in this manner does not accrue as operating time.

D. Pr ima ry Containment Isolation Valves Double isolation valver are provided on lines that penetrate the primary containment and communicate directly with the reactor vessel and on lines that penetrate the primary containment and communicate with the primary containment free space. Closure of one of the valves in each line would be sufficient to maintain the integrity of the pressure suppression system. Automatic initiation is required to minimize the potential leakage paths from the containment in the event of a loss-of-coolant accident.

4.7 STATION CONTAINMENT SYSTEMS A. Primary Containment System The water in the suppression chamber is used only for cooling in the event of an accident, i.e., it is not used for normal operation; therefore, a weekly check of the temperature and volume is adequate to assure that adequate heat removal capability is present.

Amendment No. 44, 49 166

, i VYNPS BASES: 37 (Cont'd) l The interiors of the drywell and suppression chamber are painted to prevent rusting. The inspection of the paint during each major j refueling outage, approximately once per year, assures the paint is intact. Experience with this type of paint at fossil fueled generating stations indicates that the inspection interval is adequate. 1 i

Because of the large volume and thermal capacity of the suppression I pool, the volume and temperature normally changes very slowly and monitoring these parameters daily is sufficient to establish any temperature trends. By requiring the suppression pool temperature to be continually monitored and frequently logged during periods of significant heat addition, the temperature trends will be closely followed so that appropriate action can be taken. The requirement for an external visual examination following any event where potentially high loadings could occur provides assurance that no significant damage was encountered. Particular attention should be focused on structural discontinuities in the vicinity of the relief valve discharge since these are expected to be the points of highest stress. Visual inspection of the suppression chamber including water line regions each refueling outage is adequate to detect any changes in the suppression chamber structures.

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Amendment No. 166a

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