ML20065C283
| ML20065C283 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 08/06/1982 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20065C287 | List: |
| References | |
| NUDOCS 8209230307 | |
| Download: ML20065C283 (4) | |
Text
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y"l LIMITING SAFETY SYSTD1 SETTINGS BASES RC Hieh Temperature The RC high temperature trip <618 F pr'evehts the reactor outlet temperatura l
from exceeding the design limits and acts is 'a backup trip for all power ex-
~
cursion transients.
Flux -- o Flux / Flow The power level trip setpoint produced by the reactor coolant system flow is based on a flux-to-flow ratio which has been established to accommodate flow decreasing transients from high power where protection is not provided by the high' flux / number of reactor coolant pumps on trips.
The power level trip setpoint produced by the power-to-flow ratio provides the reactor power both high power level and low flow protection in the event The power level level increases or the reactor coolant flow rate decreases.
produced by the power-to-flow ratio provides overpower DNB protection setpoint For every flow rate there is a maximum per-for all modes of pu=p operation.
missible power level, and for every power level there is a mini =um permissible Examples of typical power level and low flow rate combinations low flow rate.
for the pump situations of Table 2.2-1 that would result in a trip are as follows:
Trip would occur when four reactor coolant pumps are operating if power flow rate is 100% of full flow rate, or flow 1.
107.02 and reactor coolant is of full flow rate and power level is 100%.
rate is 9 3.5%
Trip would occur when three reactor coolant pumps are operating if' power is 80.0% and reactor coolant flow rate is 74.7% of full flow rate, or flow 2.
rate is 70.0% of full flow rate and power is 75%.
For safety calculations the maximum calibration and instrumentation errors for the power level were used. Full flow rate in the above two examples is defined as the flow calculated by the heat balance at 100% power.
1 1
B 2-5 Amendment No. 38',3a[,45 DAVIS-3 ESSE, UNIT 1 8209230307 ggogog DR ADOCK 05000346 PDR
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LIMITING SAFETY SYSTDf SETTINGS BASES The AXIAL POWER IMBALANCE boundaries are established in order to prevent re-actor ther=al limits fron being exceeded. These ther=al limits are either power peaking kW/ft limits or DNBR limits. The AXIAL POWER IMBALANCE reduces the power level trip produced by a flux-to-flow ratio such that the boundaries of Figure 2.2-1 are produced.
RC Pressure -- Low, High, and Pressure Temperature The high and low trips are provided to limit the pressure range in which re-actor operation is per=itted.
During a slow reactivity insertion startup accident from low power or a slow reactivity insertion from high power, the RC high pressure setpoint is reached before the high flux trip setpoint. The trip setpoint for RC high pressure, 2300 psig, has been established to maintain the system pressure below the safe-ty limit, 2750 psig, for any design transient. The RC high pressure trip is backed up by the pressurizer code safety valves for RCS over pressure protec-tion, and is therefore set lower than the set pressure for these valves, 2435 psig. The RC high pressure trip also backs up the high flux trip.
The RC low pressure, 1983.4 psig, and RC pressure-temaerature (12.60 Touko-established to maintain the DNB rat
-~
5662) psig, trip setpoints have been greater than or equal 'to 1.30 for those design accidents that result in a pressure reduction.
It also prevents reactor operation at pressures below the valid range of DNB correlation li=its, protecting against DNB.
High Flux / Number of Reactor Coolant Pumos On In conjunction with the flux - a flux / flow trip the high flux / number of reac-ter coolant pumps on trip prevents the minimum core DN3R from decreasing below 1.30 by tripping the reactor due to the loss of reactor coolant pump (s).
The pump monitors also restrict the pmaer level for the number of pumps in operation.
DAVIS-BESSE, UNIT 1 B 2-6 Amendment No.,&T,45
4 REACT!v!TY CONTROL SYSTEMS SarETY RCD 1h5EST10N L1"IT
- L !"; ~ 1NP-CONDITION FOR OPERATION 3.1.3.5 All safety rods shall be fully withdrawn.
Appt10 BILITY:, l' and 2**.
ACTION:
With a maximum of one safety rod not fully withdrawn, except for sur-weillance testing pursuant to Specification 4.1.3.1.2. within one hour either:
a.
Fully withdraw the rod or Declare the rod to be inoperable and apply Specification b.
3.1.3.1.
SURVE* LL ANCE REOL'IREw!NTS 4.1.3.5 Each safety red shall be determined to be fully withdrawn:
Within 15 minutes prior to withdrawal of any regulating rod a.
during sn approach to reactor criticality.
b.
At least once per 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> thereafter.
l
- 5ee Special Test Exception 3.10.1 and 3.10.2.
- With K,ff > 1.0.
i DAVIS-BESSE, UNIT 1 3/4 1 25 l
T
.a REACTIVITY CONTE 0L SYSTEMS REGULATING ROD INSERTION LD'ITS LIMITING CONDITION FOR OPERATION 3.1.3.6 The regulating rod groups shall be limited in physical insertion as shown on Figures 3.1-2a, -2b, and -2c and 3.1-3a, -3b, and -3c for the first 200 210 EFPD of operation.
If the axial power shaping rods are completely withdrawn at 200 210 EFPD for extension of cycle length, then the regulating rod groups shall be limited in physical insertion as shown on Figures 3.1-2e and 3.1-3e for the remainder of the cycle. However, if the axial power shap-ing rods are not ec=pletely withdrawn at 200 210 EFPD, then the regulating rod groups shall be limited in physical insertion as shown on Figures 3.1-2d and 3.1-3d for the remainder of the cycle. A rod group overlap of 25 25%
shall be maintained between sequential withdrawn groups 5, 6 and 7.
APPLICABILITY: MODES 1* and 2*d.
ACTION:
With the regulating rod groups inserted beyond the above insertion li=its (in a region other than acceptable operation), or with any group sequence or over-lap outside the specified li=its, except for surveillance testing. pursuant to Specification 4.1.3.1.2, either:
Restore the regulating groups to within the limits within 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />, or a.
b.
Reduce THER"AL POWER to less than or equal to that fraction of RATED THER-MAL POWIR which is allowed by the rod group position using the above fig-ures within 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />, or c.
Be in at least HOT STANDBY within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />.
NOTE: If in unacceptable region, also see Section 3/4.1.1.1.
- See Special Test Exceptions 3.10.1 and 3.10.2.
- With k,gg 2 1.0.
DAVIS-BESSE, UNIT 1 3/4 1-26 Amendment No. Jt,J2,M,R,45
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