ML090690432: Difference between revisions
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| issue date = 11/04/2008 | | issue date = 11/04/2008 | ||
| title = Unit Nos.1 and 2 - Email Request for Additional Information Re License Amendment Request (TAC Nos. MD8471 and MD8472) | | title = Unit Nos.1 and 2 - Email Request for Additional Information Re License Amendment Request (TAC Nos. MD8471 and MD8472) | ||
| author name = Wang A | | author name = Wang A | ||
| author affiliation = NRC/NRR/DORL/LPLIV | | author affiliation = NRC/NRR/DORL/LPLIV | ||
| addressee name = Schrader K | | addressee name = Schrader K | ||
| Line 21: | Line 21: | ||
==Subject:== | ==Subject:== | ||
Additional Question onCST Ken, here it is: | Additional Question onCST Ken, here it is: | ||
: 1. In the supplemental letter provided from Westinghouse, dated June 16, 2008, it is stated that "the assumed level restoration [of the steam generator water level] was reduced from no load programmed level to the narrow range lower level tap." As depicted in Figure 5.5-4 of the DCPP UFSAR, "Westinghouse Delta 54 Replacement Steam Generator," the narrow range lower level tap is positioned below the top of the steam generator U-tubes. This restoration level was used as the basis for the requested TS limit of 200,000 gallons in the CST. | : 1. In the supplemental letter provided from Westinghouse, dated June 16, 2008, it is stated that "the assumed level restoration [of the steam generator water level] was reduced from no load programmed level to the narrow range lower level tap." As depicted in Figure 5.5-4 of the DCPP UFSAR, "Westinghouse Delta 54 Replacement Steam Generator," the narrow range lower level tap is positioned below the top of the steam generator U-tubes. This restoration level was used as the basis for the requested TS limit of 200,000 gallons in the CST. | ||
It has been communicated that in the case of the limiting scenario (LOOP with natural circulation cooldown at reduced rate) the EOP would instruct operators to maintain steam generator water level between 20% and 60%, which is above the top of the U-tubes, during the entire cooldown. This is possible due to the fact that the CST upgrade was designed to provide approximately 222,600 gallons of seismically-qualified condensate as opposed to the minimum 200,000 gallons. However, after the requested change to the CST TS limit, it is possible for the licensee to legally operate with as little as 200,000 gallons available in the CST. While this volume is sufficient to meet the cooling requirements of the postulated event, it would not be enough to maintain steam generator water level between 20% and 60% for the entire duration of the event. This means that some portion of the steam generator U-tubes would become uncovered during the 8-hour cooldown. | It has been communicated that in the case of the limiting scenario (LOOP with natural circulation cooldown at reduced rate) the EOP would instruct operators to maintain steam generator water level between 20% and 60%, which is above the top of the U-tubes, during the entire cooldown. This is possible due to the fact that the CST upgrade was designed to provide approximately 222,600 gallons of seismically-qualified condensate as opposed to the minimum 200,000 gallons. However, after the requested change to the CST TS limit, it is possible for the licensee to legally operate with as little as 200,000 gallons available in the CST. While this volume is sufficient to meet the cooling requirements of the postulated event, it would not be enough to maintain steam generator water level between 20% and 60% for the entire duration of the event. This means that some portion of the steam generator U-tubes would become uncovered during the 8-hour cooldown. | ||
Revision as of 01:43, 12 July 2019
| ML090690432 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 11/04/2008 |
| From: | Wang A Plant Licensing Branch IV |
| To: | Schrader K Pacific Gas & Electric Co |
| Wang, A B, NRR/DORL/LPLIV, 415-1445 | |
| References | |
| TAC MD8471, TAC MD8472 | |
| Download: ML090690432 (2) | |
Text
From: Alan Wang Sent: Tuesday, November 04, 2008 9:49 AM To: Ken Schrader
Subject:
Additional Question onCST Ken, here it is:
- 1. In the supplemental letter provided from Westinghouse, dated June 16, 2008, it is stated that "the assumed level restoration [of the steam generator water level] was reduced from no load programmed level to the narrow range lower level tap." As depicted in Figure 5.5-4 of the DCPP UFSAR, "Westinghouse Delta 54 Replacement Steam Generator," the narrow range lower level tap is positioned below the top of the steam generator U-tubes. This restoration level was used as the basis for the requested TS limit of 200,000 gallons in the CST.
It has been communicated that in the case of the limiting scenario (LOOP with natural circulation cooldown at reduced rate) the EOP would instruct operators to maintain steam generator water level between 20% and 60%, which is above the top of the U-tubes, during the entire cooldown. This is possible due to the fact that the CST upgrade was designed to provide approximately 222,600 gallons of seismically-qualified condensate as opposed to the minimum 200,000 gallons. However, after the requested change to the CST TS limit, it is possible for the licensee to legally operate with as little as 200,000 gallons available in the CST. While this volume is sufficient to meet the cooling requirements of the postulated event, it would not be enough to maintain steam generator water level between 20% and 60% for the entire duration of the event. This means that some portion of the steam generator U-tubes would become uncovered during the 8-hour cooldown.
The NRC staff requests confirmation that the radiological release due to the postulated LOOP with natural circulation cooldown at a reduced rate remains bounded by more severe accident analyses. This confirmation should assume maximum allowable primary activity levels for normal operation and maximum allowable primary to secondary leakage for normal operation, and assume a leakage point at or near the top of the U-tube bundle.
E-mail Properties Mail Envelope Properties (419623E8C7444444BF132DA3AE69EDA2106B64D345)
Subject:
Additional Question onCST
Sent Date: 11/4/2008 9:48:32 AM Received Date: 11/4/2008 9:48:00 AM From: Alan Wang
Created By: Alan.Wang@nrc.gov
Recipients:
KJSe@pge.com (Ken Schrader)
Tracking Status: None
Post Office:
HQCLSTR02.nrc.gov
Files Size Date & Time
MESSAGE 8086 11/4/2008
Options Expiration Date:
Priority: olImportanceNormal ReplyRequested: False Return Notification: False
Sensitivity: olNormal Recipients received: