ML20149K140
| ML20149K140 | |
| Person / Time | |
|---|---|
| Site: | Trojan File:Portland General Electric icon.png |
| Issue date: | 02/17/1988 |
| From: | Cockfield D PORTLAND GENERAL ELECTRIC CO. |
| To: | |
| Shared Package | |
| ML20149K132 | List: |
| References | |
| TAC-67377, NUDOCS 8802230380 | |
| Download: ML20149K140 (6) | |
Text
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9 PORTLAND GENERAL ELECTRIC COMPANY EUGENE WATER & ELECTRIC BOARD AND PACIFIC POWER & LIGHT COMPANY Operating License NPF-1 Docket 50-344 License Change Application 163 This License Change Application requests modifications to Operating License NPF-1 for the Trojan Nuclear Plant to add new instruments for monitoring the steam generator blowdown system liquid effluent cadioactivity and flow rate.
PORTLAND GENERAL ELECTRIC COMPANY B
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D.W.[ockfield Vice President Nuclear Subscribed and sworn to before me this 17th day of February 1988.
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Notary Public of Ors'gon My Commission Expires:
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LCA 163 Page 1 of 5 DESCRTlIION OF CHANGE The following changos to Trojan Technical Speelfication (TTS) 3/4.3.3.10 "Radioactive Liquid Effluent Instrumentation", are proposed:
1.
Add.
. "or Steam Generator Blowdown Ion Exchanger Effluent (PRM-17)" to Item 1.b in Table 3.3-12 and add PRM-17 as Item 1.c in Table 4.3-8.
Operability and survelliance requirements for this instrument will be consistent with those for Item 1.B. Steam Generator Blowdown Effluent Line (PRM-10).
2.
Change Item 3.C - Steam Generator Blowdown Effluent Line Flow Rate Monitor in Tables 3.3-12 and 4.3-8 by adding additional Flow Instrument FI-4921.
3.
The phrase "or instrument de-energized" is added to the footnote on Table 4.3-8, since PRM-17 does not have an "OPERATE" switch.
REASON FOR CHANGE Portland General Electric Company (PGE) plans to implement a design change during the 1988 refueling outage which will modify the Steam Generator Blowdown System (SGBS). These changes being nede to the SGBS are shown within the cloud lines on the attached Drawing Change Notice, Piping and Inrtrument Diagram (P&ID) M-348.
The new PRM-17 is designated RE-8600 on the P&ID. PRM-9 is shown on FSAR Figure 11.2-9 (RE-4045) and I
PRM-10 is shown on FSAR Figure 9.3-2 (RE-5700).
As part of this change, the SGBS effluent flow path to the Discharge and Dilution Structure (D&DS) is being relocated.
The present flow path for untreated blowdown ef fluent is from the steam generator blowdown tank to the blowdown heat exchanger, then directly to the D&DS. Release monitoring and termination on detection of high blow-down effluent radiation is provided by the stuam generator blowdown effluent line monitor (PRM-10) which monitors fluid in the sample line upstream of the blowdown tank. This monitor provides isolation signals to the steam generator blowdown line outboard Contsinment isolation valves (MO-2808
-2810. -2812, and -2813) and to the isolation valve in the piping to the D&DS (CV-2818). Measurement of the blowdown effluent flow rate is provided by Flow Instrument FI-6715, located in the discharge line to the D&DS.
The flow path for treated blowdown effluent is from the steam generator blowdown tank to the blowdown heat exchanger, through the SGBS ion exchanger, then to the Liquid Radioactive Waste System Plant discharge header.
Effluent routed through this flow path is monitored by PRM-9 (Liquid Radwaste Effluent Line Radioactivity Monitor) and Flow Rate Monitors FT-4044 or FIY-4098 before release in the D&DS.
LCA 163 t
Page 2 of 5 The planned design change will provide a radiation monitor (PRM-17) downstream of the SGBS ion exchanger which is dedicated to blowdown systam usagn and independent of the Liquid Radwaste System. Blowdown liquid will be routed from the blowdown tank to the blowdown heat exchanger through the SGBS ion exchanger, then normally returned to the secondary Plant cycle via the main condenser. Alternatively, the SCBS liquid may be diverted from the condenser and discharged to the river via the D&DS. Capability to bypass the SGBS ion exchanger will be provided for periods when steam generator liquid quality permits and operational considerations make use of this flow path nececsary. The new effluent line radioactivity monitor PRM-17 is being added to the OGBS ion exchanger discharge line. It will be located between the SGBS ion exchanger and the point where piping branches to either the main condenser or the D&DS.
The new radiation monitor will provide isolation signals on high radiation which will isolate tht SGBS discharge to the D&DS (CV-2818) and i.he condenser (CV-4919), and will also stop blowdown by closing the blowdown tank inlet control valves (CV-4910. -4911, -4912, and -4913).
The existing steam generator blowdown monitor (PRM-10) on the steam generator blowdown sample line will continue to be utilized for alarm and SGBS automatic isolation functions.
It will still supply an isolation signal to the SCBS outboard Containment isolation valves, and will automatically terminate effluent flow (as a result of blowdown tank low level) prior to the release of high radiation from a steam generator i
tube leak. A new blowdown line effluent flow rate monitor (FI-4921) will be installed in the SGBS heat exchanger outlet piping.
This flow rate monitor will be in addition to blowdown effluent flow rate monitor FI-6715 and will provide remote indication at a recorder and riow totalizer on the steam generator blowdown control panel in the Turbine i
Building.
This change to the TTS is necessary so that SGBS effluent monitoring instrumentation in TTS 3/4.3.3.10 will be consictent with Plant design following implementation of the SGBS design change. Tha additional effluent radiation monitor (PRM-17) to be located on the SGBS ion exchanger discharge piping to the D&DS will provide effluent monitoring capability just prior to liquid release by a monitor dedicated to the steam generator blowdown flow path. This will provide direct monitoring of liquid being released to the D&DS without relying on the Liquid Radwaste System (PRM-9).
PRM-10 will provide isolation of steam genera-tor blowdcen due to a change in radioactivity level prior to dominerali-zation. The new flow rate monitor will perform the same function as the present FI-6715 monitor, that of measuring ef fluent flow rate.
The addition of this monitor (FI-4921) will mean there are two flow rate monitors in the discharge line, either of which will be capable of supplying required effluent flow rate data.
LCA 163 page 3 of 5 SIGNIFICANT HAZARDS CONSIDERATION DETERMINATIOU This proposed change will revise the list of instruments for which operability is governed by TTS 3/4.3.3.10 Radioactive Liquid Effluent Instrumentation, to incorporate modifications being implemented by a design change to the SGBS. A new steam generator blowdown ion exchanger ef fluent line gross radioactivity monitor, providing automatic termina-tion of release, is being added to Tables 3.3-12 and 4.3-8.
This new monitor (PRM-17) is being added as a result of the redesign of the SGBS effluent piping arrangement and will provide indication of the effluent radioactivity level immediately before release. A second steam generator blowdown effluent line flow rate monitor (FI-4921) is being added to Tables 3.3-12 and 4.3-8.
This new effluent flow rate monitor is also being installed as part of the SGBS design change.
The new monitor (FI-4921) performs the same function as FI-6715 but provides remote indication on the SGBS control panel in the Turbine Building.
The proposed change to the TTS will allow either flow rate monitor tc b0 used for blowdown effluent flow rate measurement.
This change does not involve a significant increase in the probability or consequences of an accident previously evaluated.
The purpose of the instrumentation being added to TTS 3/4.3.3.10 is to monitor steam genera-tor blowdown effluent radioactivity levels and flow rate.
The addition J
of this radioactivity monitor does not affect accident probability since its function is to detect and prevent a potential radioactivity release j
after an accident or potential release causing event have occurred.
Likewise, the probability of an accident is not changed by adding a blowdown flow rate instrument which provides only a monitoring function.
The consequences of an accident are likewise not increased by this change.
Radiation Monitor PRM-17, which is being added to the Technical Specifications, will be located closer to the point of effluent release j
than the present steam generator blowdown effluent monitor and will l
provide monitoring of blowdown effluent independent of the Liquid Radio-active Waste System.
Its location downstream of the SCBS ion exchanger and just upstream of the piping branch to the D&DS will allow it to pro-vide accurate indication of activity in liquid effluent being relsased.
Thus, in addition to monitorins for an increase. in activity of the steam generator liquid, this monitor will detect and prevent a release due to ion exchanger resin damage or exhaustion.
The monitor will supply isola-tion signals to terminate steam generator blowdown to the blowdown tank and to block the ion exchanger discharge path.
The present monitor (PRM-10) is not being replaced.
Rather, the new monitor will provide additional monitoring and isolation capability and will asrum4 the fune-tion of isolating the discharge valve to the D&DC. The present monitor will continue to provide alarm and blowdown termination fynettons, and its operability will still be governed by TTS.
It will continue to pro-vide isolation of steam generator blowdown at the Containnent isolation valves, thus maintaining the capability for early indication of a primary-to-secondary leak and assurance of blowdown isolation following a
LCA 163 Page 4 of 5 steam generator tube rupture. Steam generator blowdown effluent monitor-ing capability is thus being increased and improved by this change.
Section 15.6.3 of the Trojan FSAR describes the analysis of a postulated steam generator tube rupture accident.
The sequence of events initiated by such an accident is delineated, which includes termination of blowdown by the "steam generator liquid monitor", ie, PRM-10.
The accuracy of that paragraph is not affected by this change, except that the blowdown isolation signal may be provided by PRM-17.
Note that the blowdown isolation signal from the blowdown radiation monitor would be redundant to the Containment isolation signal from safety injection in either case.
The addition of the new blowdown flow rate monitor will have no effect on accident consequences. This change will make two instruments available for monitoring blowdown flow rate, thus providing additional monitoring reliability. Additionally, the new monitor adds a more accessible read-out capability by providing remote indication at the SGBS control panel in the Turbine Building. The net effect of this TTS change is to provide increased monitoring and isolation capability of the steam generator blowdown effluent path. Therefore, it will reduce the potential conse-quences of an accident and the probability for an unplanned release.
This change does not create the possibility of a new or different kind of accident from any previously evaluated.
The operability of steam genera-tor blowdown monitoring instrumentation is not relevant to accident creation.
Its purpose is to monitor steam generator blowdown flow rate and activity and provide indication of elevated radioactivity levels after an accident has occurred.
This change does not involve a significant reduction in a margin of safety.
The new radioactivity monitor to be added is the currently available replacement model for the monitor presently in use. The addi-tional flow rate monitor is of similar design and performan:e capability as the present monitor and has the added feature of remote indication.
This change adds to and enhances the steam generator blowdown ef fluent monitoring capability. It serves to decrease the potential for an undesirable release of radioactive liquid, and thus tends to increase the margin of safety.
In the April 6, 1983 Federal Reaistet, the NRC published a list of examples of amendments that are not likely to involve significant hazards concerns.
Example No. 2 from this list states:
"A change th.at constitutes an additional limitation, restriction, or control not presently included in the Technical Specifications, es, a more stringent surveillance requirement."
This example applies to the cequested changes.
Based on the above evaluation, these changes do not pose a significant hazards consideration.
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B-LCA 160 page 5 of 5 Safety / Environmental Evaluation Sumary i
Safety and environe.sntal evaluations were perfomed as required by 10 CFR 50 and the TTS.
This review determined that the proposed changes do not create an unreviewed safety question since Plant operations remain consistent with the FSAR, adequate surveillance is maintained, and there is no significant adverse impact on the environment.
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