ML20117J448
| ML20117J448 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 05/29/1996 |
| From: | SOUTHERN CALIFORNIA EDISON CO. |
| To: | |
| Shared Package | |
| ML20117J437 | List: |
| References | |
| NUDOCS 9605310178 | |
| Download: ML20117J448 (12) | |
Text
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i RWST 3.5.1 SURVEILLANCE REQUIREMENTS SURVEILLANCE FREQUENCY i
SR 3.5.1.1 Verify each SIT isolation valve is fully 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> open.
SR 3.5.1.2 Verify borated water volume in each SIT is 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> a 1680 cubic feet and s 1807 cubic feet.
SR 3.5.1.3 Verify nitrogen cover pressure in each SIT 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> is a 615 psia and s 655 psia.
SR 3.5.1.4 Verify boron concentration'in each SIT is 31 days 2 1850 ppm and s 2800 ppm.
AND bnk r ired to be performed for affected SIT Once within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> after each solution volume increase of a 1% of tank volume that is not the result of addition from the refueling water storage tank (continued) 9605310178 960529 PDR ADOCK 05000361 P
pop SAN ON0FRE--UNIT 2 3.5-2 Amendment No. 127
l l
NPF-10/15-465 ATTACHMENT "B"
)
EXISTING SPECIFICATIONS UNIT 3 1
l
[
RWST 3,5.1 SURVEILLANCE REQUIREMENTS SURVEILLANCE FREQUENCY SR 3.5.1.1 Verify each SIT isolation valve is fully 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> open.
SR 3.5.1.2 Verify borated water volume in each SIT is 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> a 1680 cubic feet and s 1807 cubic feet.
SR 3.5.1.3 Verify nitrogen cover pressure in each SIT 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> is a 615 psia and s 655 psia.
SR 3.5.1.4 Verify boron concentration in each SIT is 31 days 2 1850 ppm and s 2800 ppm.
AND i
NOTE------
Only required to be performed for affected SIT i
Once within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> after each solution volume increase of 2 1% of tank volume that is not the result of addition i
from the i
refueling water storage tank (continued)
SAN ONOFRE--UNIT 3 3.5-2 Amendment No. 116
l NPF-10/15-465 ATTACHMENT "C" REVISED SPECIFICATIONS UNIT 2
~.
RWST 3.5.1 3
SURVEILLANCE REQUIREMENTS SURVEILLANCE FREQUENCY SR 3.5.1.1 Verify each SIT isolation valve is fully 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> open.
SR 3.5.1.2 Verify borated water volume in each SIT is 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> a 1680 cubic feet and s 1807 cubic feet.
SR 3.5.1.3 Verify nitrogen cover pressure in each SIT 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> is a 615 psia and s 655 psia.
i SR 3.5.1.4 Verify boron concentration in each SIT is 31 days a4850g200ppmands2800 ppm.
AND
NOTE------
Only required to be performed for affected SIT Once within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> after each solution volume increase of a 1% of tank volume that is not the result of addition from the refueling water storage tank (continued)
I l
SAN ONOFRE--UNIT 2 3.5-2 Amendment No. 137 i
NPF-10/15-465 f
5 d
ATTACHNENT "D" REVISED SPECIFICATIONS UNIT 3
RWST 3.5.1 SURVEILLANCE REQUIREMENTS j
SURVEILLANCE FREQUENCY l
SR 3.5.1.1 Verify.each SIT isolation valve is fully 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> open.
SR 3.5.1.2 Verify borated water volume in 'each SIT is 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> a 1680 cubic feet and s 1807 cubic feet.
SR 3.5.1.3 Verify nitrogen cover pressure in each SIT 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> is a 615 psia and s 655 psia.
.SR 3.5.1.4 Verify boron concentration in each SIT is 31 days 24450220gppmands2800 ppm.
AND
NOTE------
Only required to be performed for affected SIT Once within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> after each solution volume increase of a 1% of tank volume that is not the result of addition from the refueling water l
storage tank i
i (continued)
SAN ON0FRE--UNIT 3 3.5-2 Amendment No. 146
NPF-10/15-465 ATTACHMENT "E" TECHNICAL
SUMMARY
OF THE SAFETY INJECTION TANK BORON l
CONCENTRATION CHANGE CALCULATIONS l
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- - -.-.. _ - - -. ~.. -.. -
E
)
' l Technical Summarv Backaround: The determination of the required minimum boron concentrations for alternate Reactor Coolant System (RCS) coolant sources.is performed usin the Asea Brown Boveri/ Combustion Engineering Nuclear Organization (ABB/CEN0)g 4
reload methodology.
The purpose of these calculations is to ensure the reactor core will remain 1% shut down under post Loss of Coolant Accident 1
(LOCA) conditions. This information is used to establish and verify the requirements. for the Safety Injection Tank (SIT) boron concentration Technical i
4 Specification.
The SIT boron concentration requirement is calculated using the NRC approved ABB/CEN0 ROCS computer code for conditions conservatively approximating the post LOCA refill phase.
~ Reference for ROCS Computer Code:
i CENPD-266-P-A, "The ROCS-DIT Computer Codes for Nuclear Design," April,1983, In the post LOCA scenario, the reactor core has undergone a depressurization
-and coolant blow down.
The core has been voided and the SITS discharge into i
the reactor barrel to refill the reactor vessel lower plenum and downcomer.
This SIT dischar i
Cooling System (ge covers the delay time required for the Emergency Core ECCS) flow to initiate and begin recovering the fuel and i
thereby terminate the LOCA event.
The minimum SIT boron concentration requirement is determined for the situation where the core is voided except for the SIT borated fluid.
In order to conservatively maximize the SIT boron requirements, the post LOCA core conditions are assumed to correspond to beginning(AR0) ycle-(B0C), hot zero of c power-(HZP), all CEAs (or rods) out of the core and coolant conditions of 500 F and 1100 psia.
The operating temperature is assumed conservatively high for the expected post LOCA core conditions of approximately 200 'F.
-This creates maximum boron requirements from the post LOCA, B0C, and HZP positive Moderator Temperature Coefficient (MTC) used in the calculation. The high RCS pressure is also conservative. Use of this assumption ensures the ROCS code will not credit void formation at saturated conditions which would lower the-boron requirements.
The reactivity calculation in ROCS is generated by iterating on an assumed _ SIT boron concentration.
The result of the calculation is a negative reactivity which shows the reactor core remains subcritical for the assumed boron. The reactivity result is adjusted with the appropriate biases and uncertainties.
A conservative value of 1% shut down is also maintained.
The results of this calculation are presented below.
1 Inputs:
The following list provides the key inputs to the above calculation.
List of Key Parameters A.
Rated Thermal Power 3390 Mwth B.
Nominal HFP Inlet Temperature 500 F.
C.
RCS Pressure 1100 psia D.
RCS Volumes:
3 Pressure Vessel 4876.0 ft 3
RCS Piping 1549.8 ft 3
Pressurizer 1567.9 ft 3
Steam Generators 3930.2 ft I
4 3
Reactor Coolant Pumps 459.0 ft 3
Total 2382.9 ft E.
CEA Position All Rods Out (AR0)
F.
Boron Concentration (Assumed) 2150 PPM (by weight)
G.
Time in Life
.Beginning of Cycle 9 (B0C9) d I
Note: Reactor Coolant System volumes are conservative for the 1
calculation (not Best Estimate).
4 1
4 r
i
~.
Assumptions:
The following major conservatisms are present in the-calculation of the minimum SIT boron concentration requirements.
1.
The reactor core is conservatively assumed to be 1% shut down. The 1%
shut down value corresponds to the requirements for operation in Mode 3 (HotShutDown). This ensures the General Design Criteria assumption for the reactivity control system maintaining the reactor shut down post accident will be met.
2.-
The required SIT boron concentration was conservatively calculated to be less than 2150 PPM.
The final concentration.in the Technical Specification is for 2200 PPM. This provides an additional 50 PPM of margin for the calculation.
This margin covers uncertainties in the-boron measurement.
It also provides margin to allow for Boron 10 burn out during extended reactor operation.
3.
No Control Element Assembly (CEA) worth was assumed for determination of the minimum SIT boron concentration requirement.
It is of course anticipated that a scram would occur and provide at least an additional 5% Delta-Rho shut down margin.
4.
The post LOCA temperature is assumed to be 500 F rather than a more typical post LOCA value.
The expected post LOCA temperature would be consistent with the saturated conditions determined by the containment pressure, < 45 to 50 psia.
This results in additional SIT boron requirements due to the positive MTC assumed for the reactivity requirement.
5.
RCS pressure is assumed sufficiently high to ensure the ROCS computer code will not calculate the boron concentration for saturation conditions.
This assumption conservatively excludes credit for the reactivity effect of void formation which is expected to be present under post LOCA' saturation conditions.
6.
No change in xenon concentration following shutdown was assumed.
This is conservative since the xenon concentration will continue to increase for the first 7 hours8.101852e-5 days <br />0.00194 hours <br />1.157407e-5 weeks <br />2.6635e-6 months <br /> of the event and the time frame for the SIT evaluation is conservatively set at 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />.
7.
Physics parameters assumed for the calculations were for hot full aower (HFP) BOC. These values are consistent with the time in cycle whic1 the minimum SIT boron concentration requirement is maximized.
. Results:
The ROCS computer ade calculation of base reactivity was adjusted to account for the appropriate biases, uncertainties and shut down percentage. The results of those calculations are presented below.
Reactivity Calculation:
ROCS Calculated reactivity (B0C, 500 F, 1100 psia, AR0, 2150 PPM)
]
Base Reactivity
-2.1269 % Delta Rho
. Bias
+0.3390 % Delta Rho Uncertainty
+0.2000 % Delta Rho Net Post LOCA
-1.5878 I UeTta IIio 1
Shut Down Reactivity Mode 3 Hot Shut Down
+1.0000 % Delta Rho Reactivity Margin to Limits
-0.5879 % Delta Rho The value of -0.5879 % Delta Rho represents the excess negative reactivity present after satisfying the biases, uncertainties and shut down requirements.
The negative value indicates negative reactivity margin is available and validates the assumed boron concentration for the calculation.
Therefore, the i
new validated minimum SIT boron concentration is shown to be acceptable in all respects.
j Minimum SIT Boron Concentration 2200 ppm by weight i
=
As previously mentioned, this value has been conservatively increased by 50 ppm in addition to the requirements for calculation uncertainty.
This uncertainty bounds any measurement errors in performing chemistry surveillance as well as any burn out of Boron 10.
The existing upper boron concentration limit of 2800 still ensures there will not be any boron precipitation during post LOCA recirculation flow from the containment sump.
There is no impact on the upper boron concentration limit.