05000334/LER-1979-015-01, /01T-1 on 790621:notifies That High Energy Line Break Inside Containment Could Result in Potential Steam Generator Level Bias.Caused by Heatup of Steam Generator Level Measurement Ref Leg.Tech Spec Change Submitted: Difference between revisions

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#REDIRECT [[05000334/LER-1979-015-01, /01T-0 on 790621:received Vendor Notification That High Energy Break Inside Containment Could Cause Potential Steam Generator Level Bias Leading to Delayed Protection Signals.Caused by Calculation Error]]
| number = ML19248D224
| issue date = 08/01/1979
| title = /01T-1 on 790621:notifies That High Energy Line Break Inside Containment Could Result in Potential Steam Generator Level Bias.Caused by Heatup of Steam Generator Level Measurement Ref Leg.Tech Spec Change Submitted
| author name = Werling J
| author affiliation = DUQUESNE LIGHT CO.
| addressee name =
| addressee affiliation = NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
| docket = 05000334
| license number =
| contact person =
| document report number = LER-79-015-01T, LER-79-15-1T, NUDOCS 7908130442
| package number = ML19248D204
| document type = LICENSEE EVENT REPORT (SEE ALSO AO RO), TEXT-SAFETY REPORT
| page count = 2
}}
{{LER
| Title = /01T-1 on 790621:notifies That High Energy Line Break Inside Containment Could Result in Potential Steam Generator Level Bias.Caused by Heatup of Steam Generator Level Measurement Ref Leg.Tech Spec Change Submitted
| Plant =
| Reporting criterion =
| Power level =
| Mode =
| Docket = 05000334
| LER year = 1979
| LER number = 15
| LER revision = 1
| Event date =
| Report date =
| ENS =
| abstract =
}}
 
=text=
{{#Wiki_filter:-
LICENSEE EVENT REPORT CONTROL OLOCK: l l
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8 60 Gl DOCKET NUMDE R Gd 63 EVENT DATC 74 75 REPOHT DATE t;0 EVENT DESCRIPTION AND PROBAOLE CONSEQUENCES h o
2 IThe NSSS vendor has notified BVPS that a high energy line break inside containment o
a lcould result in a potential steam generator level bias due to the heatup of the
! steam generator level measurement reference leg.
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==CAUSE==
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1 i l 1evel trip an addition 10 percent to 20 percent total Per Westinghouse Bulletin.
[il21l During the upcoming refueling outage, the S/G level reference legs will be i
a l insulated. A technical specification change is being submitted to correct the i
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NAME OF PHEPAllEH PHONE:
 
Attachment To LER 79-15/0lT-1 Beaver Valley Power Station Duquesne Light Company Docket No. 50-334 The NSSS vendor has notified BVPS that a high energy line break inside containment could result in a potential steam generator level bias due to the heatup of the steam generator level measurement reference leg.
This potential level bias could result in delayed protection signals (reactor trip and auxiliary feedwater initiation) which are based on low-low steam generator water level.
The high energy line break in containment will result in an increased reference leg water column temperature which in turn results in a decrease of water column density with a consequent apparent increase in the indicated steam generator water level (i.e., apparent level exceeding actual level).
In the case of a feedline rupture, this adverse environment could be present and could delay or prevent the primary signal arising from declining steam generator water level (low-low steam generator level). Back-up signals which may be available include the following:
overtemperature delta T, high pressurizer pressure, containment pressure, and safety injection.
For other high energy line breaks which could introduce a similar positive bias to the steam generator water level measurement, steam generator level does not provide the primary trip function and the potential bias would not interfere with needed protective system actuation.
By way of example, a containment temperature of 180F could result in a 3% bias in steam generator levels.
Refering to the attached figures (Figure 14.3-57 and Figure 14.3-58 from the BVPS FSAR for a Hot Leg DER) a containment pressure in excess of 1.5 psig (which in turn actuates safety injection, auxiliary feedwater and reactor trip) occurs prior to the containment atmosphere being heated up to 180F.
Thus, the possibility of a greater bias of the steam generator level signal above 180F for this particular case is not relevant to protection system actuation.
In correcting the steam generator water level setpoint for this bias, the reference leg bias is additive to the existing setpoint.
Per Westinghouse bulletin, the steam generator low-low level trip will be administratively increased an addition 10 percent which results in 20 percent total.
During the upcoming rebeHng outage, the steam generator level reference legs will be insulated. A technical specification change is being submitted to account for the required setpoint with the insulation installed.
56i 210
}}
 
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Latest revision as of 18:04, 25 May 2025