ML20115B359
| ML20115B359 | |
| Person / Time | |
|---|---|
| Site: | Seabrook  |
| Issue date: | 10/09/1992 |
| From: | Feigenbaum T NORTH ATLANTIC ENERGY SERVICE CORP. (NAESCO) |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NYN-92137, NUDOCS 9210150411 | |
| Download: ML20115B359 (10) | |
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Facsimile (603)474 2987 Energy Service Corporation Ted C. Feigenbaum Senior Vice President and Chief Nuclear Officer NYN 92137 October 9,1992 United States Nuclear Regulatory Commission Washington, D.C.
20555 Attention.
Document Control Desk
References:
(a)
Facility Operating License No. NPF-86, Docket No. 50-443 (b)
North Atlantic Letter NYN-92121 dated September 4,1992 " Licensee Event Report 92-11; Inoperable Cooling Tower Fans", T. C. Feigenbaum to USNRC (ci North Atlantic Letter NYN 92127 dated September 30,1992 " Licensee Amendment Request 9213 Manual Operation of Cooling Tower Fans and Sprays", T. C. Feigenbaum to USNRC
Subject:
Request for Temporary Waiver of Compliance: Manual Operation of Cooling Tower Fans and Sprays Gentlemen:
North Atlantic Energy Service Corporation (North At' antic) requests a temporary waiver of compliatee from the provisions of Seabrook Station Technical Specification Surveillance Requirement 4.7.5d.1) as it pertains to verifying that the cooling tawer fans will automatically start on a Tower Actuation (TA) signal. On August 7,1992,-in response to an NRC concern, it was identified that placing the cooling tower fan control ~ switches in the
" pull-to-lock" position precluded demonstration of operability of the cool:ng tower in accordance with Technical Specification Surveillance Requirement 4.7.5d.1). This surveillance requirement requires that operability of the cooling tower be demonstrated every 18 months by testing automatic actuation of each cooling tower fan on a TA test signal.
This surveillance was performed by taking the fan control switches out of the "p ull-t o-lo c k" position. Since the fans were not tested in their normal configuration (i.e., pull-to-lock), this aspect of the Technical Specifications was not satisfied. Therefore, the' cooling tower was not verified to be OPERABLE pursuant to Surveillance Requirement 4.7.5 d.1 ).
This condition is documented in Se'abrook Station Licensee Event Report (LER) 92-11, entitled
" Inoperable Cooling Tower Fans", which was transmitted to the NRC on September 4,1992, via North Atlantic Letter NYN-92121, [ Reference (b)].
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North Atlantic has submitted a License Amendment Request [ Reference (c)] which proposes to revise Technical Specification 3.7.5, Ultimate Heat Sink, to permit the cooling tower fans and sprays to be manually initiated, as opposed to automatically occurring, if a j
cooling tower actuatiou were to occur. To bring North Atlanti into compliance pending the NRC review of the proposed Technical Specification change, the cooling tower fan control L
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United States Nuclear Regulatory Commission October 9,1992 Attention:
Document Control Desk -
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i switches have been placed in the automatic position and the spray bypass valves have been closed when the cooling tower fans are required to be operable per the Technical Specifications. -This action will allow the fans to start automatically and the cooling tower return water to be directed to the spray header following the receipt of a TA signal. This action satisfies the requirements of Surveillance Requirement 4.7.5d.1), and is acceptable i
prior to the onset of winter conditions.
4 Description of Condition I
The original cooling tower design allowed for automatic initiation of sprays and fans
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upon receipt of a TA signal, in certain environmental conditions, however, this could result in icing of the tower's fill-tile. Ice has the potential to prevent cooling by impeding the flow of water through the fill tile. In order to address this concern, a design change was implemented to install spray bypass valves 1-SW-V-139 and 1-SW-V 140, such that upon receipt of.a TA signal, hol' service water bypasses the l
spray header and is recirculated back to the tower basin. In addition, the fan control switches were placed in the " pull to lock." position since operation with ice buildup j-on the fan blades is not recommended by the fan manufacturer. Automatic initiation
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of both the sprays and fans was replaced by proceduralized manual initiation. Upon-1 receipt of a TA signal, the operator would manually initiate spray and fan operation j
based on the combination of primary component cooling water heat exchanger outlet.
I temperature and ambient wet bulb temperature. Manual operation ensures adequate l
cooling of the service water and also ensures tile icing will not occur.
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1 Seabrook Station Technical Specification Surveillance Requirement 4.7.5d.1) requires that at least once per 18 months that automatic actuation of'ench cooling tower fan on a Tower Actuation (TA) signal be verified. The current surveillance procedure utilized by North Atlantic, to verify that the cooling tower' fans would automatically -
start upon receipt of a TA signal, was performed by taking the cooling tower fan control switches out of the " pull-to-lock" position. Since the surveillance was not
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performed with the cooling tower fans control switches in their normal configuration, j
Surveillance Requirement 4.7.5d.1) was not satisfied and the cooling tower fans were i
not demonstrated to be OPERABLE.
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Reouest for Temocrary Waiver of-Compliance I
North Atlantic is providing the justification below which demonstrates that continued j
operation during the duration of 'the requested ' waiver is consistent with protecting j
the health and safety of the public.
l 1)
Reouirement for Which a Waiver is Reouested t
f North Atlantic requests a waiver from the' requirements of Technical Specification Surveillance Requirement 4.7.5d.1).. As discussed above, North Atlantic has placed the control switcFes for the cooling tower fans in the 4
automatic position and closed the cooling tower spray bypass valsee when the -
cooling tower fans are required to be operable per the Technical Specifications.
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United States Nuclear Regulatory Commission October 9,1992..
Attention:
Document Control Desk Page three i
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L These actions will allow the cooling tower fans to start: automatically and the cooling tower return water to be directed to the spray _-header, upon receipt i
of a towcr actuation signal. These actions are acceptable prior to the onset of' winter conditions.
During - cold weather, _ with this - cooling - tower i
configurat_ ion, a' tower actuation could result in undesirable ice buildup on the l
cooling tower fill tile and fan blades. ~ Ice buildup could potentially impede the evaporative cooling process and cause damage to _tbe cooling tower fans.
i 2)
Circumstances of the Situation and Need for Prompt Action t'
Seabrook Station Unit 1 is currently.in ~a refueling outage that is scheduled to-end on November 7, 1992.
The cooling tower will be: required to be OPERABLE once the plant enters MODE 4 which is currently scheduled to.
occur on or about October 25, 1992.
As discussed above, cooling. tower j
OPERABILITY will entail placing the cooling --tower fan switches in the -
automatic position and closing the cooling tower spray bypass valves. :In this 2
configuration, if a tower actuation were.to occur' the cooling tower fans would-start and spray flow would be directed over the cooling tower fill tile. During j
the Fall and Winter ' months, there is a potential for ice buildup-on both ~ the -
j-cooling tower fans and the fill tile. Therefore, North-Atlantic believes that it is prudent to' operate the-cooling tower with the fans =in the " pull-to-lock" j
position and the spray bypass valves open to prevent the possibility of damage to the plant equipment.
3)
Compensatory Action -
North Atlantic _has reviewed the need for compensatory action. Since. it has l
been determined by analysis that..there is sufficient / time and procedural l
guidance available to manually initiate cooling tower spray and fan operation i
following the cooling tower design basis event, no further compensatory action is deemed necessary. The proposed temporary waiver of compliance places the.
cooling tower in the desired long term configuration..This configuration places the cooling tower fan and spray bypass valves in the same configuration as l~
requested by License Amendment' Request 9213, (Reference (c)].
4-4)
Evaluation of Safety Sienificance h
- North Atlantic 7 has determined by_ analysis that there is_ sufficient time and l
procedural guidance available to manually initiate cooling tower spray and fan operation following the cooling towers design _ basis event. This analysis -is available for NRC review at Seabrook' Station - and -is being docketed under separate correspondence. In _ addition, operators.are periodically. trained.to initiate appropriate action regarding manual _ cooling tower operation. There -
is-also adequate procedural guidance and main control r'oom alarm indication j_
available to alert operators to. the need-to initiate cooling tower fan and spray operation. Therefore, operation of the cooling tower with the sprays and fans -
j; manually controlled does not require immediate operator action to mitigate the a
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Attention:
Documer t Contral Desk.
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effects of an accident,- and the proposed temporary waiver of compliance does l
not create a safety concern.
An ev'duation of the safety significance of manually controlling cooling tower j
spray and fan operation is provided in Enclosure 1.
i 5)
Duration of Reauested Waiver
-The duration of the requested waiver is until NRC review of Licensee I
j Arcendment Request (LAR) 9213 is complete and a license amendment.having
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immediate effectiveness is issued. North Atlantic has requested that the review '
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and issuance of LAR 9213 be completed'by March 31, 1993 or a's soon as -
l possible.
I 6)
Basis for No Sinnificant Harards _
North Atlantic has determined by analysis that there is sufficient time available to manually initiate cooling tower spray and fan operation following the cooling j
tower design basis event.
This analysis is available for NRC review at' Seabrook Station and - is _ being docketed under separate correspondence.
l Manual operation-of. the cooling' tower fans and L sprays will ~ preclude
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undesirable ice buildup on the cooling tower fill tile and fans.. Based on this, North Atlantic has determined that the coolir.g towers are - fully capable-of 1
j fulfilling their intended function following the cooling tower design basis event.
I A No Significant Hazards Consideration Determination for the requested waiver l:
is provided in Enclosure 1.
l 7)
Environmental Consecuences The requested waiver involves no environmental consequences. If the cooling -
tower fans and sprays are operated manually, the cooling tower _ remains fully functional and capable-of operating as the ultimate heat -sink if required.
Therefore, manual operation. docs - not affect: any accident-analyses or the associated radiological consequences nor_ does it affect systems associated _with the control of radiological or non-radiological effluents.
i This request for a temporary waiver of compliance has been reviewed by the Station _
q Operation Review Committee _(SORC).
United'Sta:es Nuclear Regulatory Commission October 9,1992 Attention:
Document Control Desk Page~ five Should you have any further questions regarding this request for temporary waiver of compliance, please contact Mr Terry L. liarpster, Director of Licensing Services at (603) 474 9521 extension 2765.
Very tr y yours,
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Ted-. Feige m
TCF:MDO/ tad Enclosure ec:
Mr. Thomas T. Martin Regional Administrator United States Nuclear Regulatory Commission Region I 4U Allenda..: Road King of Prussia, PA 19406 Mr. Gordon Edison, Sr. Project Manager Project Directorate 13 Division of Reactor Projects U.S. Nuclear Regulatory Commission
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Washington, DC 20555 Mr. Noel Dudley i
NRC Senior Resident Inspector P.O. Box 1149 I
Seabrook, NH 03874 Mr. John Shedlosky, Acting Section Chief Project Section 3B i
United States Nuclear Regulatory Commission Region 1 l
475 Allendale Road King of Prussia, PA 19406 4
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ENCLOSIIRE I TO NYN-02137 -
i EVALUATION OF-SAFETY SIGNIFICANCE AND NO SIGNIFICANT HAZARDS -
CONSIDERATION FOR REQUESTED WAIVER OF COMPLIANCE i
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i EVALUATION OF SAFETY SIGNIFICANCE AND NO SIGNIFICANT llAZARDS CONSIDERATION FOR REQUESTED WAIVER OF COMPLIANCE EVALUATION OF SAFETY SIGNIFICANG 1
i The cooling tower functions as the backup ultimate heat sink, ind is capable of cooling the sersice' water system heat loads following a safe shutdown seismic event which assuines the collapse and greater than 95% blockage of the circulating water system tunnels.
The design basis for the cooling tower also assumes a Loss of Coolant Accident (LOCA) and a Loss of Offdte Power (LOP). The design basis heat load for the tower thert. fore consists of the residual heat removal (RHR) system heat rejection, containment building spray (CBS) system heat rejection, diesel generator cooling system heat rejection, the cooling tower pumps, and other small loads imposed
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on the primary component cooling water (PCCW) system during the accident.
During the initial stage of the LOCA the Emergency Core Cooling System (ECCS) operates in the injection phase. In this phase, the water supply for the ECCS pumps is the Refueling Water Storage Tank (RWST) and the heat loads imposed on the cooling tower by the ECCS equipment is minimal. The majority of the heat load on the cooling tower occurs following switchover from the ECCS injection phase to the j
recirculation phase. During the recirculation phase, valves are aligned to draw water from the containment recirculation sump to be re-injected into the reactor vessel and containment building. This water, which had previously been cool water from the RWST, now must be cooled in the RHR and CBS heat exchangers, prior to re-injection. This heat is ultimately rejected to the cooling tower and when this occurs, a significant heat load is imposed on the cooling tower.
l An analysis was performed by North Atlantic which demonstrated that, if the cooling tower is manually operated, a minimum of 74 minutes will be available for operator action to initiate cooling tower sprays and fans prior to reaching the basin limiting i
temperature of.80'F during a single train post-LOCA cooldown or 87'F during a two l
train cooldown. This time is greater than the 20 minute minimum operator response time specified in NUREG 0800. NUREG 0800 Section 6.3 s:ates in part that where manual action is used, a sufficient time (greater than 20 minutes) be available for the l'
operator to respond. This analysis is available for NRC review at Seabrook Station and is being docketed under separate correspondence.
Manual operation of the cooling tower will continue to allow the cooling tower to meet its design requirements
'and will enhance the safe operation of Seabrook Station by ensuring that the cooling tower is operated in an ice free condition.
Although the post-LOCA cooldown is the design oasis case for the cooling tower, a normal cooldown has also been evaluated with respect.o manual cooling tower spray and fan operation. The normal cooldown differs from the post-LOCA cooldown in that the initial heat load to the cooling tower is higher in the normal cooldown case.
This higher load results from normal plant acat loada, which would be isolated in the i
post-LOCA cooldown case remaining in service and therefore requiting cooling.
As in the post-LOCA cooldown case, the cooling tower basin is assumed to be at-its maximum initial temperature and minimum volume. The tower basin temperature is again limited to a maximum temperature of.80*F prior to initiating cooling tower 1
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-spray and fan operation. This 80'F limit is conservative for this case as it is based on the larger heat loads experienced in the -post LOCA cooldown case. With ~the maximum normal cooldown heat load, and assuming a loss of offsite power which adds the heat rejection from both Cesel generators, greater than 106 minutes is available-for _ operator action to start the cooling tower sprays -and fans-prior to reaching _a cooling tower basin average temperature of 80'F.
There is adequate procedural guidance, operator training, and main control room 4
indication available, to alert.the operator to the need to initiate cooling tower fan and spray operation. During the postulatcd design basis scenario, operators are directed to monitor cooling tower performance ~ at step 10 of Seabrook Station emergency j
operating procedure E 0, " Reactor Trip -or Safety injection". This step directs the operator to verify ultimate heat sink operation if the coollag tower is the ultimate 1 heat sink the operator is directed to-initiate cooling tower spray and fan operation based on the combination of wet bulb temperature and_ PCCW heat exchanger outlet i
temperature. If the criteria to initiate cooling-tower spray _ and fan operation has i
not been _ reached when step 10 of emergency. operating procedure E 0 is reached, operators will periodically monitor cooling tower operation to ascertain the need for i
spray and fan operation. In addition, there are PCCW high temperature alarms on i
the main control board, _which 'will alert operators to the L aced to initiate cooling-tower spray and fan operation,
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If a Tower Actuation were to occur without an accompanying entry into the Emergency Operating Procedures, Abnormal Procedure OS1216,01," Degraded Ultimate
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Heat Sink" provides guidance on cooling tower fan' and spray operation.
Operator training is conducted using abnormal and emergency simulator scenarios.
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Several of these scenarios emphasize monitoring ultimate heat sink performance; These training scenarios verify that appropriate -operator action is taken during a l_
cooling tower actuation occurring with and without entry-into emergency operating i
procedure E-0, " Reactor Trip or Safety injection".
l Based upon the above, there is sufficient time ~and procedural guidance.available-to manually initiate cooling tower spray and fan operation following the cooling to_wer l-design basis event.
In. addition, operators are periodically trained to initiate
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appropriate ; ation regarding manual cooling tower operation, There is;also adequate procedural guidance and main control room alarm indication available to-alert and -
i direct operators to initiate cooling tower fan and spray operation.
Therefore, i
operation of the cooling tower with the sprays a'nd fans manually controlled does not require immediate-operator action to mitigate the effects of an accident, Land the proposed temporary waiver of compliance does not create' a safety concern.
In conclusion, the proposed temporary waiver of compliance will allow cooling tower spray and fan operation to be manually initiated by aperators as opposed to automatically occurring during a cooling tower actuation. This.is1necessary to prevent 7
icing of the cooling tower tiles and fan blades during cooling tower-operation when ambient temperature is below freezing and will enhance the safe operation of the plant. The surveillance requirements will continue to verify that-the cooling tower is OPERABLE and capable of_ performing its design function as the alternate Ultimate Heat Sink.
As discussed 'above,-sufficient time is available for the operators to
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t man'ually initiate cooling tower spray and fan operation.
Therefore, there is no significant increase in_ the safety consequences associated with the temporary waiver i
of compliance.
DETERM! NATION OF NO SIGNIFICANT HAZARDS l
1.
The proposed temporary waiver of compnance does not involve a~ significant j
increase in the probability or consequences of an accident previously evaluated.
4' The temporary waiver of compliance affects only the operating mode for the cooling tower fans. Chapter 9, Section 9.2.5.2 of the Updated Final Safety Analysis Report (UFSAR) recognizes the manual operating mode of the cooling tower fans and sprays by stating that greater than 30 minutes is availabic, following the ' design basis event, 4
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in which to initiate fan and/or spray operation. It has been determined by North Atlantic through analysis that at least _74 minutes will be available to the operators in which to take manual action and initiate' cooling tower fan and spray operation.
This is an acceptable amount of time in which to initiate manual action and is greater than the 20 minute minimum specified in NUREG 0800. Therefore, the probability 4
l of an accident previously evaluated in the UFSAR is not significantly increased by the proposed _ temporary waiver of compliance. The analysis is available for NRC review at Seabrook-Station and is being docketed under s'eparate correspondence.
The cooling tower is automatically aligned as the ultimate heat sink following a safe shutdown seismic event which assumes blockage of the circulating water tunnels and l
subsequent loss of Service.1 Water (SW) system pressure.
Manual control of the cooling tower, while retaining the automatic alignment to the tower, will not adversely -
affect the ability of the cooling tower to function in this capacity. As discussed aoove, sufficien' time exists for_ the manual initiation of cooling tower sprays and fans following the seismically induced Loss Of Coolant Accident (LOCA). Additionally, there is adequate procedural guidance, operator _ training and alarm indications to alert and direct operators to initiate cooling tower fan and spray operation.
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With the ultin4 ate heat sink available,. all-safety systems will function as: designed.
j This change will therefore have no_ adverse affect on the dos.es to members of the public from any previously analyzed accident :and therefore the consequences or an accident previously evaluated in the UFSAR' is not. significantly increasni by thi.-
proposed temporary waiver of compliance.
2.
The proposed temporary waiver of compliance doe; not. create the possibility of a new or different kind of accident' from any accident previously evaluated.
The proposed temporary waiver of ' compliance modifies the cooling tower operating mode from automatic actuation to manual actuation. This is not a new mode of operation; this mode of opuetion is present y acknowledged and described in UFSAR l
Chapter 9.
Manual control of the cooling tower will not adversely affect the availability of the cooling tower or its heat removal capability. The cooling tower spray bypass valves,1-SW-V-139 and 1 SW.V-140, are included in the Inservice Test Program and are periodically surveilled pursuant to Technical Specification 3
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'Surveilhnce Requirement 4.0.$. This ensures that the valves will operate as designed, when required. The cooling tower fans are verified to be OPERABLE, in part, by l-starting the fans from the main control board (MCB). This requirementris pursuant
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to Technical Specification Surveillance. Requirement 4,7,5c.1) and verifies that the-fans can be started from the MCB. Thus, no credible failure mechanism is created
-by manual control of the cooling tower which could result in the initiation.of an accident. Therefore, the possibility of-a' new or different kind of accident from any accident previously evaluated in the UFSAR is not created.
3.
The proposed temporary waiver of compliance does noi result in a significant
. reduction in the margin of safety.
I The Bases for Technical Specification 3/4.7.5 state that' the OPERABILITY of tim 4
cooling tower ensures that sufficient cooling capability is available to provide normal cooldown of the facility or to mitigate the affects of accident conditions within-4 l
acceptable limits.
The proposed temporaryL waiver of_ compliance modifies the operation of the cooling tower sprays and fans from-automatic to manual initiation.
Manual operation of the cooling. tower sprays and fans will not-adversely affect i
cooling tower operation or its heat removal capability and the cooling tower will-still -
be verified to be OPERABLE.
An OPERABLE Cooling Tower ens' res that 'the u
assumptions in the Bases of Technical Specifications are not affected and ensures that j
the margin of safety is not reduced.
i The cooling tower -is designed to withstand a safe shutdown seismic event which 9
assumes the collapse of _ the circulating water system tunnels. 2The cooling tower l
design basis also assumes a Loss of Coolant Accident and Loss' of Offsite Power. In this limiting scenario, greater than 74 minutes are available to initiate cooling tower.
sprays and fans following the seismic event. Adequate procedural guidance, operator training, and alarm indications are provided to facilitate operation of the fans and.
sprays. Following this manual action, the full capability of the cooling tower ultimate heat sink is available to meet the requirements-of the design basis event.
Therefore, the assumptions in the Bases of Technical Specifications are not affected e
and the proposed temporary waiver. of compliance' willinot result. in a significant.
- reduction-in the margin of safety.
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