ML20155F178
| ML20155F178 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 10/05/1988 |
| From: | NORTHEAST NUCLEAR ENERGY CO. |
| To: | |
| Shared Package | |
| ML20155F175 | List: |
| References | |
| NUDOCS 8810130176 | |
| Download: ML20155F178 (5) | |
Text
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Docket No. 50-423 B13051 Proposed Revision to Technical Specifications End of Life Moderator Temperature Coefficient i
October 1988
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h REACTIVITY CONTROL SYSTEMS EQQERATOR TEMPERATURE COEFFICIENT LinjilNG CONDITION FOR OPERATION l
3.1.1.3 The moderator temperature cotfficient (MTC) shall be:
less positive than +0.5 x 10'4 AW8f for all the rods withdrawn, a,
beginning of cycle life (BOL), condition for power levels up to 70%
i RATED THERMAL POWER with a linear ramp to 0 Ak/k/8F at 100% RATED l
THERMAL POWER, b.
Less negative than 4.75 x 10'4 AW/of for the til roos withdrawn, end of cycle life (EOL), RATED THERMAL POWER condition.
APPLIC ABILITY _: Specification 3.1.1.3a. - MODES 1 and 2* only*ly**.
Specification 3.1.1.3b. - MODES 1, 2, and 3 on t
ACTION:
I a.
With the HTC more positive than the limit of Specification 3.1.1.3a.
above, operation in MODES I and 2 may proceed provided:
1.
Control rod withdrawal limits are established and maintained i
sufficient to restore the MTC to less positive than the above limits within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> or be in HOT STANDBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />. These withdrawal limits shall be in addition to the i
insertion limits of Specification 3.1.3.6.
l 2.
The control rods are maintained within the withdrawal limits i
established above until a subsequent calculation verifies that the MTC has been restored to within its limit for the all rods l
withdrawn condition; and j
3.
A Special Report is prepared and submitted to the Commission.
I pursuant to Specification 6.9.2, within 10 days, des:rlbing the i
value of the measured MTC, the interim control rod withdraual 1
limits, and the predicted average core burnup necessary for restoring the positive MTC to within its limit for the all,?ds withdrawn condition.
b.
With the MTC more negative than the Ilmit of Specification 3.1.1.3b.
above, be in HOT SHUTDOWN within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.
' With K,gg greater than or equal to 1.
- See Special Test Exceptions Specification 3.10.3.
1 HILLSTONE - UNIT 3 3/4 1-4 i
REACTIVITY CONTROL SYSTEMS j
SURVEILLANCE REOUIREMENTS l
l 4.1.1.3 The MTC shall be determined to be within its limits during each i
fuel cycle as follows:
I a.
The MTC shall be measured and compared to the BOL limit of Specif t-i cation 3.1.1.3a., above, prior to initial operation above 5% of l
RATED THERMAL POWER, after each fuel loading; and I
b.
The MTC shay 1 be measured at any THERMAL POWER and compared to 4.0 x 10' Ak/k/'F (all rods withdrawn, RATED THERMAL POWER l
l condition) within 7 EFPD after reaching an equilibrium boron concen-l tration of 300 ppm.
In the event t MTC is more negative than 4.0 x 10'gis comparison indicates theAk/k/'F, thel 1
remeasured, and compared to the EOL MTC 11.ait of Specification i
3.1.1.3b., at least once per 14 EFP0 during the remainder of the 1
fuel cycle, r
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MILLSTONE - UNIT 3 3/4 1-5 j
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3/4.1 REACTIVITY CONTROL SYSTEMS BASES 3/4.1.1 BORATION CONTROL j
3/4.1.1.1 and 3/4.1.1.2 SHUTDOWN MARGIN i
A sufficient SHUTDOWN MARGIN ensures that:
(1) the reactor can be made i
suberitical from all operating conditions, (2) the reactivity transients asso-ciated with pestulated accident conditions are controllable within acceptable limits, and (3) the reactor will be maintained sufficiently subcritical to preclude inadvertent criticality in the shutdown condition.
i SHUTDOWN KARCIN requirements vary throughout core life as a function of fuel depletion, RCS boron concentration, and RCS T The nost restrictive condition occurs at EOL, with T at no load opeM@ing temperature, and is associated with a postulated st858 line break accident and resulting uncon-trolled RCS cooldown.
In the analysis of this accident, a minimum SHUTDOWN MARGIN of 1.6% Ak/k is required to control the reactivity transient.
Accordingly, the SHUTDOWN MARGIN requirement is based upon this limiting condition and is consistent with FSAR safety analysis assumptions.
With T less than 2000F, the reactivity transien'.. resulting from a postulated st$l8 line break cooldown are minimal.
A 1.6% Ak/k SHUTDOWN MARGIN is required to provide protection against a boron dilution accident.
3/4.1.1.3 MODERATOR TEMPERATURE COEFFICIENT The limitations on moderator temperature coefficient (HTC) are orovided to ensure that the value of this coefficient remains within th Ilmiting condition assumed in the FSAR accident and transient analyses, j
The HTC values of this specification are applicable to a specific set of plant conditions; accordingly, verification of HTC values at conditions other than those explicitly stated will require extrapolation to those conditions in order to permit an accurate comparison.
The most negative HTC, value equivalent to the most positive moderator density coefficient (MDC), was obtained by incrementally correcting the HDC used in the FSAR analyses to nominal operating conditions.
)
HILLSTONE - UNIT 3 B 3/4 1-1 I
REACJIVITY CONTROL SYSTEMS BASES MODERATOR TEMPERATURE COEFFICIENT (Continued)
These corrections involved.
(1) a conversion of the MDC used in the FSAR safety analyses to its equivalent MTC, based on the rate of change of moderator density with temperature at RATED THERMAL POWER conditions, and (2) subtracting from this value the largest differences in MTC observed between E0L, all rods withdrawn, RATED THERMAL POWER conditions, and those most adverse conditions of moderator temperature and pressure, rod insertion, axial power skewing, and xenen concentration that can occur in normal operation and lead to a significantly more negative EOL MTC at RATED THERMAL POWER.
These corrections transformed the MDC value used in the FSAR safety analyses into the limiting MTC value of 47.5 pcm/eF.
The MTC value of 40.0 pcm/'F represents a conservative MTC value at a core condition of 300 ppm equilibrium baron concentration, and is obtained by making corrections for burnup and soluble boron to the limiting MTC value of -47.5 pcm/of.
The Surveillance Requirements for measurement of the MTC at the beginning and near the end of the fuel cycle are adequate to confirm that the MTC remains within its limits since this coefficient changes slowly due principally to the reduction in RCS boron concentration associated with fuel burnup.
3/4.1.1.4 MINIMUM TEMPERATURE FOR CRITICAllTY This specification ensures that the reactor will not be made critical l
with the Reactor Coolant System average temperature less than 551.
This limitation is required to ensure:
(1) the noderator temperature coefficient is within it analyzed temperature range, (2) the trip instrumentation is within its normal operating range, (3) the P 12 interlock is above its setpoint (4) the pressurizer is capable of being in r OPERABLE status with a steam bubble, and (5) the reactor vessel is a>ove its minimum RT temperature, NDT i
3/4.1.2 BORATION SYSTEMS The Boron injection System ensurer that negative reactivity control is available during each mode of facility operation.
The components required to perform this function include:
(1) borated water sources, (2) charging pumps, (3) separate flow paths (4) boric acid transfer pumps, and (5) an emergency power supply from OPERABLE diesel generators.
With the RCS aver.ge temperature above 200, a minimum of two boron injection flow paths are required to ensure single functional capability in the event an assumed failure renders one of the flow paths inoperable.
The boration capability of either flow path is sufficient to provide a SHUTDOWN MILLSTONE UNIT 3 B 3/4 1 2
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