ML20206B663
| ML20206B663 | |
| Person / Time | |
|---|---|
| Site: | Grand Gulf  |
| Issue date: | 04/03/1987 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20206B665 | List: |
| References | |
| TAC-63558, NUDOCS 8704100003 | |
| Download: ML20206B663 (2) | |
Text
i1 BASES 3/4.4.4 CHEMISTRY The water chemistry limits of the reactor coolant system are established to prevent damage to the reactor materials in contact with the coolant.
Chloride limits are specified to prevent stress corrosion cracking of the stainless steel.
The effect of chloride is not as great when the oxygen con-centration in the coolant is low, thus the 0.2 ppa limit on chlorides is per-mitted during POWER OPERATION.
During shutdown and refueling operations, the temperature necessary for stress corrosion to occur is not present so a 0.5 ppm concentration of chlorides is not considered harmful during these periods.
Conductivity measurements are required on a continuous basis since changes in this parameter are an indication of abnormal conditions.
When the conductivity is within limits, the pH, chlorides and other impurities affect-ing conductivity must also be within their acceptable limits.
With the con-ductivity meter iroperable, additional samples must be analyzed to ensure that the chlorides are not exceeding the limits.
The surveillance requirements provide adequate assurance that concentra-tions in excess of the limits will be detected in sufficient time to take cor-rective action.
3/4.4.5 SPECIFIC ACTIVITY The limitations on the specific activity of the primary coolant ensure that the 2 hour2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> thyroid and whole body doses resulting from a main steam line I
failure outside the containment during steady state operation will not exceed small fractions of the dose guidelines of 10 CFR 100.
The values for the-limits on specific activity represent interim limits based upon a parametric evaluation by the NRC of typical site locations.
These values are conserva-tive in that specific site parameters, such as site boundary location and
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meteorological conditions, were not considered in this evaluation.
The ACTION statement permitting POWER OPERATION to continue for limited time periods with the primary coolant's specific activity greater than 0.2 microcuries per gram DOSE EQUIVALENT I-131, but less than or equal to 4.0 mi-crocuries per gram DOSE EQUIVALENT I-131, accommodates possible iodine spiking phenomenon which may occur following changes in THERMAL POWER.
Operation with specific activity levels exceeding 0.2 microcuries per gram DOSE EQUIVALENT j
I-131 but less than or equal to 4.0 microcuries per are restricted to no more than 48 consecutive hours. gram DOSE EQUIVALENT I-131 Information obtained on iodine spiking will be used to assess the parameters associated with spiking phenomena. A reduction in frequency of 1sotopic analysis following power changes may be permissible if justified by I
the data obtained.
1 Closing the main steam line isolation valves prevents the release _of activity to the environs should a steam line rupture occur outside containment.
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GRAND GULF-UNIT 1 8 3/4 4-3 AmendmentNo.28l
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REACTOR COOLANT SYSTEM BASES 3/4.4.5 SPECIFIC ACTIVITY (Continued)
The. surveillance requirements provide adequate assurance that excessive specific activity levels in the reactor coolant will be detected in sufficient time to take corrective action.
3/4.4.6 PRESSURE / TEMPERATURE LIMITS All components in the reactor coolant system are designed to withstand the effects of cyclic loads due to system temperature and pressure changes.
- y These cyclic loads are introduced by normal load transients, reactor trips, and startup and shutdown operations.
jt used for design purposes are provided in Section 3.9 of the FSAR.Tl 2 various categori
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and shutdown, the rates of temperature and pressure changes are limited so thatDuring startup 1
the maximum specified heatup and cooldown rates are consistent with the design assumptions and satisfy the stress limits for cyclic operation.
During heatup, the thermal gradients in the reactor vessel wall produce
' thermal stresses which vary from compressive at the inner wall to tensile at the outer wall.
the tensile stresses induced by the internal pressure.These thermal induced com Therefore, a pressure-temperature curve based on steady state conditions, i.e., no thermal stresses, represents a lower bound of all similar curves for finite heatup rates when the inner wall of the vessel is treated as the governing location.
i The heatup analysis also covers the determination of pressure-temperature limitations for the case in which the outer wall of the vessel becomes the con-trolling location.
tensile stresses which are already present.The themal gradients established during h The thermal induced stresses at the outer wall of the vessel are tensile and are dependent on both the rate of heatup and the time along the heatup ramp; therefore, a lower bound curve similar to that described for the heatup of the inner wall cannot be defined.
Subse-quently, for the cases in which the outer wall of the vessel becomes the stress controlling location, each heatup rate of interest must be analyzed on an individual basis.
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The reactor vessel materials have been tested to determine their initial RT The RT for welds and base saterial in the closure flange region is NDT.
NDT i 10'F. The initial hydrostatic test pressure was 1563 psig. The results of these tests are shown in Table B 3/4.4.6-1.
Reactor operation and resultant fast neutron, E greater than 1 Mev, irradiation will cause an increase in the RT Therefore, an adjusted reference temperature, based upon the fluence, NDT.
phosphorus content and copper content of the material in question, can be Guide 1.99, Revision 1, " Effects of Residual Elements on Predicted Damage to Reactor Vessel Materials."
The pressure / temperature limit curve, Figure 3.4.6.1-1, curves A', B' and C', includes predicted adjustments for this shift in RT for the end of life fluence. Curves B' and C' are coincident NDT with curves B and C, respectively.
GRAND GULF-UNIT 1 B 3/4 4-4 AmendmentNo.32l
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