ML20236N588
| ML20236N588 | |
| Person / Time | |
|---|---|
| Site: | Trojan File:Portland General Electric icon.png |
| Issue date: | 08/06/1987 |
| From: | PORTLAND GENERAL ELECTRIC CO. |
| To: | |
| Shared Package | |
| ML20236N571 | List: |
| References | |
| TAC-66096, NUDOCS 8708120022 | |
| Download: ML20236N588 (2) | |
Text
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REACTOR COOLANT SYSTEM BASES The 10 GPM IDENTIFIED LEAKAGE limitation provides allowance for a limited amount of leakage from known sources whose presence will not
. interfere with the detection of UNIDENTIFIED LEAKAGE by the leakage detection systems.
The CONTROLLED LEAKAGE '. lmitation restricts operation when the total flow from the reactor coolant pump seals exceeds 20 GPM with the Reactor Coolant Pump seal return control valves full open at a nominal RCS pressure of 2230 psig. This limitation ensures that in the event of a LOCA, the safety injection flow will not be less than assumed in the accident analyses.
The total steam generator tube leakage limit of 1 GPM for all steam generators ensures that the dosage contribution from the tube leakage will be limited to a snell fraction of Part 100 limits in the event of either a steam generator tube rupture or steam line break The 1 GPM limit is consistent with the assumptions used in the analysis of these accidents. The 500 gpd leakage limit per steam generator ensures that steam generator tube integrity is maintained in the event of a main steam line rupture as under LOCA conditions.
PRESSURE BOUNDARY LEAKAGE of any magnitude is unacceptable since it may be indicative of an impending gross failure of the pressure boundary.
Therefore, the presence of any PRESSURE BOUNDARY LEAKAGE requires the unit to be promptly placed in COLD SHUTDOWN.
As an example of different types of leakage, consider a leak in an RCS drain valve weld.
This leak could initially be detected by the RCS leakage detection system.
Because the exact location of the leak is not immediately known, the leak could be initially classified as UNIDENTIFIED LEAKAGE.
If the led is determined to be located downstream of the drain isolation valve, th; le3k co@d be isolated by retorquing the drain valve.
Because this leakagt is isolay'fe, it would be reclassified as IDENTIFIED LEAKAGE.
Had this same leak occurred upstream of the isolation valve, it would be considered as PRESSURE BOUNDARY LEAKAGE, since it could not be isolated.
3/4.4.7 CHEMISTRY l
The limitations on Reactor Coolant System chemistry ensure that corrosion of the Reactor Coolant System is minimited and reduces the potential for Reactor Coolant System leakage or failure due to stress corrosion. Maintaining the chemistry within the Steady State Limits provides adequate corrosion protection to ensure the structural integrity of the Reactor Coolant System over the life of the plant.
The associated ef fects of exceeding the oxygen, chloride and fluoride limits are time and temperature dependent.
Corrosion studies show that operation may be continued with contaminant concentration levels in excess of the Steady TROJAN-UNIT 1 B 3/4 4-3 8706120022 Q $$44 k
PDR ADOCK ppg C"
REACTOR COOLANT SYSTEM BASES State Limits, up to the Transient Limits, for the specified limited time intervals without having a significant effect on the structural integrity of the Reactor Coolant System. The time interval permitting continued operation within the restrictions of the Transient Limits provides time for taking corrective actions to restore the contaminant concentrations to within the Steady State Limits.
1 The surveillance requirements provide adequate assurance that con-I centrations in excess of the limits will be detected in sufficient time l
to take corrective action.
3/4.4.8 SPECIFIC ACTIVITY The limitations on the specific activity of the primary coolant ensure that the resulting 2 hour2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> doses at the site boundary will not exceed an appropriately small fraction of Part 100 limits following a steam generator tube rupture accident in conjunction with an assumed steady state primary-to-secondary steam generator leakage rate of 1.0 GPM.
The ACTION statement permitting POWER OPERATION to continue for limited time periods with the primary coolant's specific activity
> 1.0 pCi/ gram DOSE EQUIVALENT I-131, but within the allowable limit shown on Figure 3.4-1, accommodates possible iodine spiking phenomenon which may occur following changes in THERMAL POWER.
Reducing Tavg to <500*F prevents the release of activity should a steam generator tube rupture since the saturation pressure of the primary coolant is below the lift pressure of the atmospheric steam relief valves.
The surveillance requirements provide adequate assurance that excessive specific activity levels in the primary coolant will be detected in sufficient time to take corrective action.
Information obtained on iodine spiking will be used to assess the parameters associated with spiking phenomena. A reduction in frequency of isotopic analyses following power changes may be permissible if justified by th* data obtained.
3/4.4.9 PRESSURE / TEMPERATURE LIMI15 All components in the Reactor Coolant System are designed to withstand the effects of cyclic loads due to system temperature and pressure changes.
These cyclic loads are introduced by normal load transients, reactor trips, and startup and shutdown operations.
The various categories of load cycles used for design purposes are provided in Section 5.2 of the FSAR.
During startup and shutdown, the rates of temperature and pressure changes are limited so that the maximum specified heatup and cooldown rates are consistent with the design assumptions and satisfy the stress limits for cyclic operation.
TROJAN-UNIT 1 B 3/4 4-4 Amendment 778 L
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