ML20073B238

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Proposed TS 3/4.2.2, APRM Setpoints
ML20073B238
Person / Time
Site: River Bend Entergy icon.png
Issue date: 09/12/1994
From:
ENTERGY OPERATIONS, INC.
To:
Shared Package
ML20073B231 List:
References
NUDOCS 9409210246
Download: ML20073B238 (4)
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Text

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'O d I / /'H '1 REACTOR PROTECTION SYSTEM INSTRLMENTATION SETPOINTS (Continued)

Average Power Range Monitor (Continued)

'1 The APRM trip system is calibrated using heat balance data taken during  !

steady state conditions. Fission chambers provide the basic input to the system and therefore the monitors respond directly and quickly to changes due to transient operation for the case of the Neutron Flux-High setpoint; i.e.,

for a power increase, the THERMAL POWER of the fuel will be less than that indicated by the neutron flux due to the time constants of the heat transfer  !

associated with/the fuel. - For the Flow 81ased Simulated Thermal Power-High setpoint, a time constant is introduced into the flow biased APRM in order to l simulate the fuel thermal transient characteristics. A more conservatiire maximum value is used for the flow biased setpoint as shown in Table 2.2.1-1.

The APRM setpoints were selected to provide adequate margin for the Safety Limits and yet allow operating margin that reduces the possibility of unneces-sary shutdown. The flow referenced trip setpoint must be adjusted by the yg ication 3.2.2 in order to maintain these marginh l unn c mn _ m3 -

3. Reactor Vessel Steam Dome Pressure-High High pressure in the nuclear system could cause a rupture to the nuclear ,

system process barrier resulting in the release of fission products. A pressure increaAe while operating will also tend to increase the power of the reactor by compressing voids thus adding reactivity. The trip will quickly reduce the neutron flux, counteracting the pressure increase. The trip setting is slightly higher than the operating pressure to permit normal operation witnout spurious trips. The setting provides for a wide margin to the maximum allowable design pressure and takes into account the location of the pressure measurement compared to the highest pressure that occurs in the system during a transient.

This trip setpoint is effective at low power / flow conditions when the turbine control valve fast closure and turbine stop valve closure trips are bypassed.

For a load rejection or turbine trip under these conditions, the transient analysis indicated an adequate margin to the thermal hydraulic limit.

4. Reactor Vessel Water level-Low The reactor vessel water level trip setpoint nas been used in transient  !

analyses dealing with coolant inventory decrease. The scram setting was chosen l f ar enough below the normal operating level to avoid spurious trips but high I enough above the fuel to assure that there is adequate protection for the fuel and pressure limits.

RIVER BEND - UNIT 1 B 2-7 Amendment No. 42 9409210246 940912

{DR ADOCK 05000458 PDR

- POWER DISTRIBUTION LIMITS 3/4.2.2 APRM SETPOINTS LIMITING CONDITION FOR OPERATION 3.2.2 The APRM flow biased simulated thermal power-high scras trip setpoint (S) and flow biased neutron flux-upscale control rod block trip setpoint (SRE')

shall be established according to the following relationships: 5

a. Two Recirculation Loop Operation s l Trip Setpoint Allowable Value 5 1 (0.66W + 48%)T S 1 (0.66W + 51%)T S

~ RB 1 (0.66W + 42%)T S RB 1 (0.66W + 45%)T

b. Single Recirculation Loop Operation Trip Setpoint Allowable Value i S 1 (0.66W + 42.7%)T S 1 (0.66W + 45.7%)T S

RB 1 (0.66W + 36.7%)T Sgg 1 (0.66W + 39.7%)T j where: 5 and Sag are in percent of RATED THERMAL POWER, W = Loop recirculation flow as a percentage of the loop recirculation INSERT A J1 w whic d w e etcar i r  :

ra oo FA LON RATE HE R P) d ded b the  :'

RE XI F TIO OF LI ING E ENS (CMF D)- Fis (ap ied ly 1 tha _ r_eg t ,.0 APPLICABILITY: OPERATIONAL CONDITION 1, when THERMAL POWER is greater than or equal to 25% of RATED THERMAL POWER.

ACTION:

7 With the APRM flow biased simulated thermal power-high scram trip setpoint and/or ,

the flow biased neutron flux-upscale control rod block trip setpoint less conser- i vative than the value shown in the Allowable Value column for S or Sgg, as above -

determined, initiate corrective action within 15 minutes and adjust 5 and/or S RB  ;

to be consistent with the Trip Setpoint value

  • within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> or reduce THERMAL l POWER to less than 255 of RATED THERMAL POWER within the next 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />. '

Tf].~0 ad' tAs

" Wit M LP0 Ec.;^;r ^J. d ' A M [rathe han adjusting the APRM se ints, the APRW gain gaa be adjusted sirch that theM PRM readings m E 2'a n

  • a ;> <

-"" *w- d5banrovided that the adjusted APRM reading does not h'1005ofRATEDTHERMALPOWER,andanoticeoftheadjustmentisposted ex;eed on the reactor cont 1.

in A. CAlettb T31.0 i g wk[Ott)APRM 4 fedi is sesM te R V R SEND - UNIT 3/4 2-7 V3 1 Amendment No.31 l s

INSERT A T = 3 x FRTP + 1 provided CMFLPD s 0.6 x FRTP + 0.4, otherwise  :

4 x CMFLPD 'l 1

FRTP  !

T= j CMFLPD T is applied only ifless than or equal to 1.0.  ;

FRTP is the FRACTION OF RATED THERMAL POWER. ,

CMFLPD is the CORE MAXIMUM FRACTION OF LIMITING POWER DENSITY.

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l POWER DISTRIBUTION LIMITS  !

_ SURVEILLANCE REQUIREMENTS 4.2.2 The FRTP and CMFLPD shall be determined, the value of T calculated, and the most recent actual APRM flow biased simulated thermal power-high scram and flow biased neutron flux-upscale control rod block trip setpoints verified to be within the above limits or adjusted, as required: *

a. At least once per 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, *
b. l Within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> after completion of a THERMAL POWER increase of at l 1 east 15% of RATED THERMAL POWER, and
c. Initially.and at least onc h hr s the reactor is operat-ing withtfC WCPO W g F '
d. The provisions of Specification 4.0.4 are not applicable.

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l RIVER BEND - UNIT 1 3/4 2-7a Amendment No.3I' J

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