ML20205J306
| ML20205J306 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 01/24/1986 |
| From: | SACRAMENTO MUNICIPAL UTILITY DISTRICT |
| To: | |
| Shared Package | |
| ML20205J285 | List: |
| References | |
| TAC-61473, NUDOCS 8601300151 | |
| Download: ML20205J306 (4) | |
Text
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RANCHO SECO UNIT 1 TECHNICAL SPECIFICATIONS Safety Limits and Limiting Safety System Settings
~2.2 SAFETY LIMITS, REACTOR SYSTEM PRESSURE Applicability Applies to the limit on reactor coolant system pressure.
Obj ective To maintain the integrity of the reactor coolant system and to prevent the release of significant amounts of fission product activity.,
Specification 2.2.1 The reactor coolant system pressure shall not exceed 2750 psig when
'there are fuel assemblies in the reactor vessel.
2.2.2 The nominal setpoint of the pressurizer code safety valves shall be less than or equal to 2500 psig. -
Bases The reactor coolant system (1) serves as a barrier to prevent radionuclides in the reactor coolant from reaching the atmosphere.
In the event of a fuel cladding failure, the reactor coolant system is a barrier against the release of fission products. Establishing a system pressure limit helps to assure the integrity of the reactor coolant system. The maximum transient,ressure allowable in the reactor coolant system pressurp yessel under the ASME code,Section III, is 110 percent of design pressure.t2; The maximum transient pressure allowable in the reactor coolant system piping, valves, and fittings under ANSI Section 831.7 is 110 percent of design pressure. Thus, the safety limit of 275 140>< established.g23psig (110 percent of the 2500 psig design pressure) has been The settings for the reactor high p and the pressurizer code safety valves (2500 psig) L5,'ssure trip ( 355 psig) have been established to assure that the reactor coolant system pressure safety limit is not exceeded. The initial hydrostatic test was conducted at 3125 psig (125 percent of design pressure) to verify the integrity of the reactor coolant system. Additional assurance that the reactor coolant system pressure does not exceed the safety limit is provided by setting.the pressurizer electromatic relief valve at 2450 psig.
This setpoint is above normal 140>< transients limited by setting the reactor trip at <2355 psig and sufficiently low to assure limited dependence on safety valves iiperation.
REFERENCES (1) FSAR, section 4 (2) FSAR, paragraph 4.3.8.1 (3) FSAR, paragraph 4.2.4 2-4 Proposed Amendment No. 140 86o1300151Og%g PDR ADOCK O PDR;
RANCHO SECO UNIT 1 TECHNICAL SPECIFICATIONS Safety Limits and Limiting Safety System Settings B.
Pump Monitors The pump monitors prevent the minimum core DNBR from decreasing below the CHR correlation limit by tripping the reactor due to (a) the loss of two reactor coolant pumps in one reactor coolant loop, an.d (b) loss of one or two reactor coolant pumps during two-pump operation. The punp monitors also restrict the power level to 55 percent for one reactor coolant pump operation in each loop.
C.
Reactor coolant system pressure 3
During a startup accident from low power or a slow rod withdrawal from i
high power, the system high pressure trip set point is reached before the nuclear overpower trip set point. The trip setting limit shown in 140x Figure 2.3-1 for high reactor coolant system pressure (2355 psig) has i
been established to maintain the system pressure below the safety limit (2750 psig) for any design transient (1) and minimize the chcllenges to the EM0'e and code safeties.
t The low pressure (1900 psig) and variable low pressure (12.96 Tout - 5834) trip set point shown in Figure 2.3-1 have been established to maintain the DNB ratio greater than or equal to the CHF correlation limit for those design accidents that result in a pressure reduction.
(2,3)
Due to the calibration and instrumentation errors the safety analysis used a variable low reactor coolant system pressure trip value of
~
(12.96 Tout - 5884).
D.
Coolant outlet temperature The high reactor coolant outlet temperature trip setting limit (618 F) shown in Figure 2.3-1 has been established to prevent excessive core coolant temperatures in the operating range.
Due to calibration and instrumentation errors, the safety analysis used a trip set point of 620 F.
E.
Reactor Building pressure The high Reactor Building pressure trip setting limit (4 psig) provides positive assurance that a reactor trip will occur in the unlikely event of a steam line failure in the Reactor Building or a loss of coolant accident, even in the absence of a low reactor coolant system pressure trip.
F.
Shitdown bypass In order to provide for control rod drive tests, zero power physics testing, and startup procedures, there is provision for bypassing certain segments of the reactor protection system. The reactor protection system segments which can be bypassed are shown in Proposed Amendment No.140 2-7
RANCHO SECO UNIT 1 TECHNICAL SPECIFICATIONS
.e Safsty Lilits end Limiting 7
l Table 2.3-1 Safety System Settings REACTOR PROTECTION SYSTEM TRIP SETTING LIMITS One Reactor Coolant Pump Four Reactor Coolant Pumps Three Reactor Coolant Pumps Operating in Each Loop Operating (Nominal Operating (Nominal (Nominal Operating Shutdown Operating Power - 100%)
Operating Power - 75%)
Power - 49%)
Bypass
- 1. Nuclear Power,1 of rated, max.
104.9 104.9 104.9 5.0I3I
- 2. Nuclear power based on flow 1.06 times flow minus 1.06 times flow minus 1.06 times flow minus Bypassed and Imbalance,1 of rated, max.
reduction due to reduction due to reduction due to Imbalance (s)
Imbalance (s)
Imbalance (s)
- 3. Nuclear power based on pump (5)
NA NA 55 Bypassed monitors, 1 of rated, max.
140 --
- 4. High reactor coolant system 2355 2355 2355 1820(4I pressure, psig max.
- 5. Low reactor coolant system Pressure, psig ein.
1900 1900 1900 Bypassed
- 6. Variable low reactor coolant 12.96 Tout-5834(II 12.% Tout-5834III 12.96 Tout-5834III Bypassed system pressure, psig min.
- 7. Reactor coolant temp. F., max.
618 618 618 618 -
- 8. High Reactor Building 4
4 4
4 pressure, psig max.
- 9. Anticipatory reactor trip (6)
Autostop gil pressure Autostop j1 pressure Autostop 11 pressure 50 psig I'3 50 psig 50 psig I
WP goverggr oil pressure WP goverggr oli pressure MFP gover(ngr oil pressure 50 psig 588 50 psig 183 50 psig si (1) T is in degrees Fahrenheit (F).
out (2) Reactor coolant system flow,1.
(3) Administratively controlled reduction set only during reactor shutdown.
(4) Automatically set when other segments of the RPS (as specified) are bypassed.
4 (5) The pump monitors also produce a trip on: (a) loss of two reactor coolant pumps in one reactor coolant loop, and (b) loss of one or two reactor coolant pumps during two-pump operation.
140 +-
(6) This trip is disabled below 451 power.
(7) Indicative of a Turbine Trip.
(8) Indicative of loss of both Main Feed pumps.
2-9 Proposed Amendment No. 140
~ ' 'o e<
RANCHO SECO UNIT 1
)
TECHNICAL SPECIFICATIONS Safety Limits and Limiting Safety System Settings Figure 2.3-1 Protective Systems Maximum Allowable Setpoints, Pressure Vs Temperature 2600 f
~~
P = 2355 psig T = 618 140 h
Acceptable Operation E.[
2200 __
"g g
Unacceptable t
Operation q
f a
/
2000 o
e P = 1900 psig 4
800 540 560 580 600 620 640 Reactor Outlet Temperature, F Proposed Amendment No. 140 2-10