ML20035B699
| ML20035B699 | |
| Person / Time | |
|---|---|
| Site: | Pilgrim |
| Issue date: | 03/29/1993 |
| From: | BOSTON EDISON CO. |
| To: | |
| Shared Package | |
| ML20035B698 | List: |
| References | |
| NUDOCS 9304050003 | |
| Download: ML20035B699 (1) | |
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3.2
, BASES (Cont'd)
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- Drywell Temperature The drywell-temperature limitations of Specification 3.2.H.1 ensure that I
safety related equipment will not be subjected to excess temperature.
i Exposure to excessive temperatures may degrade equipment and can cause loss of its operability.
l The temperature elements for monitoring drywell temperature specified in Table 3.2.H were chosen on the basis of their reliability, location, and r
their redundancy (dual - element RTD's). These temperature elements are-the primary elements used for the PCILRT.
The " nominal instrument elevations" provided in Tables 3.2.H and 4.2.H assist personnel in locating the instruments for surveillance and maintenance purposes and define the approximate containment region to be monitored. The " nominal instrument elevations" are not intended to
-i provide a precise instrument location.
The temperature limits specified in 3.2.H.1 are based on the BEco report entitled Drywell Temperature Report, dated January 28, 1982. The limits
-l derived from this report take into consideration the long-term effects of amoient temperature on equipment design limits and material degradation of components required for accident mitigation or plant shutdown. The evaluation process addressed the actual assessment of potential damage and the determination of equipment status from the-standpoint of both qualifiestion integrity (for safety-related equipment) and reliability to perform its intended function.
If the drywell temperature exceeds the limits specified in 3.2.H.1 an engineering evaluation must be initiated in order to determine whether any safety related component has been adversely affected.
The limiting drywell temperature value of 215 F (Section 3.2.H.2) was 4
selected as to guarantee that ECCS trips occur on/or before present Technical Specification values.
The time interval of 30 minutes between successive drywell temperature instrument readings (Section 3.2.H.1) was selected so as to guarantee that ECCS trips occur on/before present Technical Specification values in the event of a drywell temperature excursion in excess of 215 F.
i The instrument check interval of once per shift'provides adequate assurance of equipment operability based upon engineering judgement.
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2 93040500CX3 930329 PDR ADOCK 05000293 P
PDR Amendment No. 106 73b
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