B14340, Proposed TS Table 3.3.3, Reactor Protection Sys (Scram) Instrumentation Requirements

Proposed TS Table 3.3.3, Reactor Protection Sys (Scram) Instrumentation Requirements

ML20127E015
Person / Time
Site:	Millstone
Issue date:	01/12/1993
From:	NORTHEAST NUCLEAR ENERGY CO.
To:
Shared Package
ML20127E009	List: B14340, Proposed TS Table 3.3.3, Reactor Protection Sys (Scram) Instrumentation Requirements ML20127E006
References
B14340, NUDOCS 9301190124
Download: ML20127E015 (9)

Text

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ps hgt No. SE21]i  !

Bl.4340  :

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l Attachment 1 H111 stone Nuclear Power Station, Unit No. 1 Main Steam Line Radiation Monitor Trip Function Proposed Changes to lechnical Specifications P

E January 1993' 9301190124 DR 930112

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ADOCK 05000245 PDR-

TABLE 3.1.1 (Continued)

REACTOR PROTECTION SYSTEM (SCRAM) INSTRUMENTATION REQUIREMENTS .

Minimum Number- -

of Operable Modes in which Function Inst. Channels Trip Function Trip Level Setting Must Be Operable Action

• per Trip (1) REFUEL / STARTUP/ HOT System SHUTDOWN (8,11) STANDBY RUN 2 Turbine Condenser low 2 23 in. Hg. Vacuum X (3) X (3) X A or C Vacuum 2 Main Steamline Radiation s 7 x Normal Full Power X (12) X (12) X (12) A or C Background ,

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4 (6) Main Steamline Isolation i 10% Valve Closure X (3) X (3) X A or C '

Valve Closure 2 Turbine Control Valve See Section 2.1.2 F. X (4) X (4) X (4) A or C Fast Closure 2 . Turbine'Stop Valve i 10% Valve Closure X (4) X (4) X (4) A or C Notes: 1. There shall be two operable or tripped trip systems for each function.

2. Permissible to bypass, with control rod block, for reactor protection system reset in REFUEL and SHUTDOWN positions of the reactor mode switch.

3.

Bypassed when reactor pressure is < 600 psig.

4. Bypassed when first stage turbine pressure is less than that which corresponds to 50% rated reactor thermal power.

4 Millstone Unit 1 3/4'l-4 Amendment No. J/, ff, E) 0052 1

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TABLE 3.I.1 (Continued)

Reactor Protection System (Scram) Instrumentation Requirements .I Notes:

5. IRM's are bypassed when mode switch is placed in RUN. The detector for each operable IRM channel shall be fully inserted until the associated APRM channel is operable and indicating at least 3/125 full scale.

6. The design permits closure of any one valve without a scram being initiated. -

7. May be bypassed when necessary by closing the manual instrument isolation valve for scram of PS-1621 A through D during purging for containment inerting or deinerting.

8. When the reactor is subcritical and the reactor water temperature is less than 212*F, only the following trip functions need to be operable:

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a. Mode Switch in SHUTDOWN

b. Manual Scram -

c. High Flux IRM

d. Scram Discharge Volume High Level

e. APRM Reduced High Flux -

9. Not required to be operable when primary containment integrity is not required.

10. With the mode switch in RUN position an inoperative trip function also requires an associated APRM "downscale alarm."

.11. Trip functions are not required to be operable if all control rods are fully inserted, and either electrically ,

or hydraulically disarmed in accordance with Specification 4.1.D.  ;

12. Trip function may be bypassed for up to two hours per occurrence while placing condensate demineralizers in service. l  ;

s Millstone Unit 1 3/4 1-5 Amendment No. J, J7, JJ t 0062 l

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TABLE 3.1.1 (Continued)

Reactor Protection System (Scram) Instrumentation Requirements ,

0 Action: If the first column cannot be met for one of the trip systems, that trip system shall be tripped. If the first column cannot be met for both trip systems, the appropriate actions listed below shall be taken:

A. Initiate insertion of operable rods and complete insertion of all operable rods within four hours.

B. Reduce power level to IRM range and place mode switch in the STARTUP/ HOT STANDBY position within eight hours.

C. Reduce turbine load and close main steam line isolation valves within eight hours.

oo An APRM will be considered inoperable if there are less than two LPRM inputs per level or there are less than 50%

of the normal compliment of LPRM's to an APRM.

• oo One inch on the water level instrumentation is 127 inches above the top of the active fuel.

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Amendment No. J, J2, JJ Millstone Unit 1 3/4 1-Sa 0062

TABLE 3.2.1 INSTRUMENTATION THAT INITIATES PRIMARY CONTAINMENT ISOLATION FUNCTIONS Minimum Number of Operable Instrument Channels Per Trip System (1) Instruments Trio Level Settina Action (3) 2 Reactor low Water 2127 inches above top of active fuel A 2 Reactor Low Low Water 79 (+4-0) inches above top of active fuel A 2 (4) High Drywell Pressure 1 2 psig A 2 (2) (5) . High Flow Main Steamline < 120% of rated steam flow B 2 of 4 in each of High Temperature Main 2 subchannels Steamline Tunnel i 200*F B 2 (6) High Radiation Main (

steamline Tunnel 17 times normal rated power background B 2 Low Pressure Main 2 825 psig B Steamlines 2 High Flow Isolation 164 inches 2 trip setting (water differential C Condenser Line on steam line) 2 150 inches.

44 inches 2 trip setting (water differential on water side) 2 35 inches.

(1) Whenever, primary containment integrity is required, there shall be two operable or tripped trip systems for each function, except for low pressure main steamline which only need be available in the RUN position.

(2) Per each steamline.

(3) Action: If the first column cannot be met for one of the trip systems, that trip system shall be tripped. If the first column cannot be met- for both trip systems, the appropriate actions listed below shall be taken:

A. Initiate an orderly shutdown and have reactor'in cold shutdown condition in 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

B. Initiate an orderly load reduction and have reactor in HOT STANDBY within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />.

C. Close isolation valves in isolation condenser system.

(4) May be bypassed when necessary by closing the manual instrument isolation valve for PS-1621, A through D, during purging for containment inerting or deinerting.

(5) Minimum number of operable instrument channels per trip system requirement does not have to be met for a steamline if both containment isolation valves in the line are closed.

(6) Trip' function may be bypassed for up to two hours per occurrence while placing condensate demineralizers in l service.

Millstone Unit 1 3/4 2-2 Amendment No. J7, EJ 0063

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i, 3.1 REACTOR PROTECTION SYSTEM B'ASES Discharge of excessive amounts of radioactivity to the site environs is prevented by the air ejector off-gas monitors which cause an isolation of the main condenser off-gas line, provided the limit for a 15 minute period specified in Specification 3.8 is not exceeded. The trip function may be bypassed for up to two hours per occurrence while placing a condensate domineralizer in service. This evolution is approximately one half hour in duration. A two hour per occurrence time limit has been selected as a conservative measure to minimize the overall time that this trip function is bypassed. Operating experience has shown that there is risk of a spurious isolation while placing a condensate demineralizer in service.

The main steam line isolation valve closure scram is set to scram when the isolation valves are 10% closed from full open in three out of four lines. This scram anticipates the pressure and flux transient which would occur when the valves close. By scramming at this setting all thermal margins and pressure limits are met during the resultant transient. Ref.

Section 7.2 of the UFSAR.

A reactor mode switch is provided which actuates, or bypasses, the various scram functions appropriate to the particular plant operating status.

Ref. Section 7.2 of the UFSAR.

The manual scram function is active in all modes, thus providing for a manual means of rapidly inserting control rods during all modes of reactor operation.

The IRM and APRM systems provide protection against excessive power levels and short reactor periods in the REFUEL and STARTUP/ HOT STANDBY modes.

A source range monitor (SRM) system is also provided to supply additional neutron level information during startup but has no scram functions. Thus the IRM and APRM systems are required in the REFUEL ard STARTUP/ HOT STANDBY modes. In the power range, the APRM provides the required protections; thus, the IRH system is not required in the RUN mode.

The high reactor pressure, high drywell pressure, reactor low water level, and scram discharge volume high level scrams are required for STARTUP/H0T STANDBY and RUN modes of plant operation. They are, therefore, required to be operational for these modes of reactor operation.

The requirement to have all scram functions except those listed in Note 8 of Table 3.1.1 operable in the REFUEL and SHUTDOWN mode is to assure that shifting to the REFUEL mode during reactor power operation does not diminish the need for the reactor-protection system. As indicated in Note 11 of Table 3.1.1, no trip functions are required to be operable if all control rods are fully inserted, and either electrically or hydraulically disarmed, since this condition assures maximum negative reactivity insertion.

The turbine concenser low vacuum scram is only required during power operation and must be bypassed to start up the unit. At low power conditions, a turbine stop valve closure does not result in a transient which could not be handled safely by other scrams, such as the APRM.

Millstone Unit 1 B 3/4 1-4 Amendment No. #

0080

o, 3' 1 REACTOR PROTECTION SYSTEM l BASES l l

The requirement that the IRM's be inserted in the core when the APRM's  !

read 3/125, or lower, of full scale assures that there is proper overlap in  !

the neutron monitoring systems and thus, that adequate coverage is provided for all ranges of reactor operation.

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Millstone Unit 1 B 3/4 1-4a Amendment No.

0080 t

l 3.2 PROTECTIVE INSTRUMENTATION DASES 200*F is low enough to detect leaks of the order of 5 to 10 gpm; thus, it is capable of covering the entire spectrum of breaks. For large breaks, it is back-up to high steam flow instrumentation discussed above, and for small breaks with the resultant small release of radioactivity, gives isolation before the guidelines of 10 CFR 100 are exceeded.

High radiation monitors in the main steamline tunnel have been provided to detect gross fuc1 failure. This instrumentation causes closure of Group 1 valves, the only valves required to close to prevent further release to the environment. With the established setting of seven times normal background, and main steamline isolation valve closure, fission product release is limited so that 10 CFR 100 guideline values are not exceeded for the most rapid failure mechanism postulated (control rod drop accident). The trip function may be bypassed for up to two hours per occurrence while placing a condensate domineralizer in service. This evolution is approximately one half hour in duration. A two hour per occurrence time limit has been selected as a conservative measure to minimize the overall time that this trip function is bypassed. Operating experience has shown that there is risk of a spurious isolation while placing a condensate demineralizer in service.

Pressure instrumentation is provided which trips when main steamline pressure at the turbine drops below 825 psig. A trip of this instrumentation results in closure of Group 1 isolation valves. In the " REFUEL," " Shutdown,"

and "STARTUP/ HOT STANDBY" made this trip tunction is bypassed. This function is p ::vided primartly to provide protection against a pressure regulator malfunction which would cause the control and/or bypass valves to open. With the trip set at 825 psig, inventory loss is limited so that fuel is not uncovered and peak clad temperatures are much less than 1500'F; thus, there is no release of fission products other than those in the reactor water.

High pressure actuation of the Isolation Condenser (IC) will be a backup to direct activation on Low-Low level; similar to other ECCS systems. Activa-tion is based on the high pressure signal (1085 PSIG for 15 seconds) which occurs after MSIV closure on Low-Low water level, SRV actuation, and subse-quent repressurization. The activation of the IC requires only the opening of nnrmally closed valve IC-3 in the condensate return line. This ' valve is

)owered by the safety-grade DC battery. All valves in the system are powered ay safety grade AC or DC power and are also used for containment isolation.

All are normally in the open position (other than 10-3). The IC system is safety Class 2 and is seismically qualified. The shell side water volume is sufficient for approximately 30 minutes of operation at rated conditions without nakeup. Two sources of makeup are available. For small break mitiga-tion, less than 10 minutes of operation is required, and generally at less than rated conditions.

Millstone Unit 1 B 3/4 2-3 Amendment No.

0079 l

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3.2 PROTECTIVE INSTRUMENTATION BASES Two sensors on the isolation condenser supply and return lines are  :

provided to detect line failure and actuate isolation action. The sensors on the supply and return sides are arranged in a 1 out of 2 logic and to meet the single failure criteria, all sensors and instrumentation are required to be operable. The isolation settings and valve closure times are such as to prevent core uncovery or exceeding site limits.

The instrumentation which initiates ECCS action is arranged in a dual bus system. As for other vital instrumentation arranged in this fashion, the Saccification preserves the effectiveness of the system even during periods w1en maintenance or testing is being performed.

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. Millstone Unit 1 B 3/4 2-3a Amenment No.

0079 l

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