ML20006G042
| ML20006G042 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 02/20/1990 |
| From: | Shelton D TOLEDO EDISON CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| 1772, NUDOCS 9003020135 | |
| Download: ML20006G042 (8) | |
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TOLEDO
%ss EDISON A Centenar (norgy Cwmeny p;
I DONALD C. SHELTON t*
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lo9 m S23m Docket Number 50-346 g
License Number NPF Serial Number 1772 4
February 20,- 1990 United States Nuclear Regulatory Commission
-Document Control Desk Vashington, D. C. 20555
Subject:
Toledo Edison Comments on Draft Fire Protection Program Safety Evaluation Report Gentlemen:
Toledo Edison is enclosing several comments on the Davis-Besse Nuclear Power Station Fire Protection Program Safety Evaluation Report (SER), which was reviewed in draft form during a meeting at the NRC offices on January 9-10, 1990. The comments are' based on the SER draft attached to the the USNRC Heeting Summary dated. February 2, 1990 (TE Log Number 3159). Many of the enclosed-comments were discussed at the meeting, but could not be incorporated into the. draft SER during the meeting because Toledo Edison had not provided a
-docketed reference to substantiate the information.
~The draft SER identified four open items as follows:
1.
Circuit supervision and alarms associated with the fire-detection and alarm system.
2.
Fire protection program Technical Specifications 3.
Post-fire reactor coolant pump seal injection and cooling methodology 4.
Voluntary loss of offsite power capability As stated in its letter of February 16, 1990 (Serial 1757), Toledo Edison.is currently considering a plant modification to resolve Open Item 1.
As further discussed on February 14, 1990 with the NRC Project Manager, resolution of Open Item 1 is not required before the April 1990 NRC Fire Protection Inspection.
Toledo Edison vill provide a discussion of the proposed modification at a later date. This modification will be implemented prior to restart from the 8th refueling outage, as discussed at the October 4-5, 1989 NRC Heeting. This schedule is consistent with schedules for other fire protection modifications not required to comply with Appendix R requirements.
THE TOLEDO EDISON COMPANY EDISON PLAZA 300 MADISON AVENUE TOLEDO, OHlO 43652 9ooso2oias9oo22g46
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,Dock:;t Nunber 50-346 License Number NPF-3 Serial, Number 1772
.Phge 2 Toledo Edison intends to incorporate the fire protection program into the USAR subsequent to the sixth refueling outage.
Concurrent with or shortly after the USAR revision, Toledo Edison vill submit a License Amendment Request to delete the Fire Protection Program Technical Specifications. Requesting the license amendment after the fire protection inspection and the sixth refueling outage was recommended by the NRR fire protection reviewer at on-site meetings during the fall of 1989.
Information to close Open Item 3, reactor coolant pump seal injection and cooldown methodology, was provided to the NRC by Toledo Edison in its letter dated February 16, 1990.
, to this letter provides additional information necessary to close the final open item, voluntary loss of offsite power capability. This information describes the background and approach being implemented at Davis-Besse and the regulatory basis for this approach. Toledo Edison believes that this information satisfactorily resolves concerns raised by the NRC Staff reviewer during the January SER review meeting. provides suggested changes to the draft SER and provides the necessary backup information to support the suggested changes.
Toledo Edison appreciates the opportunity to comment on the draft SER.
The comments in this letter are made to facilitate issuance of the SER vith current information, which should mimimize potential discrepancies during the Davis-Besse Fire Protection Inspection scheduled for the week of April 23, 1990.
If you'have any questions concerning this matter, please contact Mr. R. V. Schrauder, Manager - Nuclear Licensing at (419) 249-2366.
Very tru
- yours, DCV/ssg Attachments cc:-
P._M. Byron, DB-1 NRC Senior Resident Inspector A. B. Davis, Regional Administrator, NRC Region III D. J. Kubicki, NRC/NRR Staff Reviewer T. V. Vambach, DB-1 NRC Senior Project Manager
' Docket Number-50-346 Liesnsa Numbar NPF-3 Serial Number 1772 Attachment l'
- P* age l' Response to Draft SER Open Item 4 Use of Offsite Power During Serious Station or Control Room Fire BACKGROUND Analysis to assure the plant can be safely shut down following an Appendix R fire scenario must consider the possibility that offsite power is not available..Various fire scenarios involve situations where fire damage to electrical equipment, turbine trip, or various associated circuit faults may cause the loss of offsite power.
In providing Appendix R safe shutdown hardware protection and procedures, a number of factors are considered including the following:
severity and location of the fire potential for affecting offsite power availability potential for affecting safe shutdown cables or equipment number, timing, and location of operator actions overall plant safety consistency of approach with other abnormal or emergency procedures for non-fire scenarios The NRC has expressed reservation that the approach used at Davis-Besse relating to the use of offsite power to support post-fire safe shutdown may not be "sufficiently conservative." The specific concern is that the approach may be defeating a viable source of power to safe shutdown equipment by In promptly tripping offsite power and relying on onsite emergency power.
this situation, if both diesel generators vould fall to start or run, power to support safe shutdown equipment may be unavailable.
The intent of the approach used at Davis-Besse is to allow maximum flexibility to the operators in deciding whether to.use offsite power to support post-fire safe shutdown equipment, with a preference to use it if available.
As the fire scenarios or symptoms become more complex, the post-fire shutdown procedures are designed to be more restrictive to assure that operators perform the actions necessary in a timely manner to protect or to use the safe shutdown equipment required.
Certain specific scenarios require the operators to_ trip offsite power. The following information is provided to more fully describe and to justify the acceptability of this approach.
APPROACH The shutdown procedures at Davis-Besse use a phased approach whereby plant shutdown, if required, is performed using the normal shutdown procedure, the rapid shutdown abnormal procedure, and/or the Reactor Trip Emergency Procedure.
Based on the location and severity of the fire, one of two serious
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x Docht Nu;ber 50-346
'Lic nsa Nurbar NPF.
Serial Number 1772' Phge 2 fire procedures may be used to dictate the operational approach. All of these procedures provide for the operator to use offsite power while it is available or until potential fire-induced faults within the system make it desirable for the operators to trip offsite power and proceed using onsite emergency power. Only in specific cases where the safe shutdown analysis (including the operator action timelines) dictates that tripping offsite power is the best or only alternative does the procedure direct the operator to initiate a voluntary loss of offsite power.
The_ operators' response to a fire-induced or voluntary loss of offsite power can best be illustrated by an example of a fire progression from a small to serious fire.
Upon receiving a report of a fire, the station fire abnormal procedure is entered. This procedure is a upper-tier procedure that controls overall activities related to the fire such as confirmation, firefighting I
response and coordination with other procedures such as the serious fire procedures and the Emergency Plan. The station fire procedure instructs operators to preview the serious fire Abnormal Procedures that vould apply to the area or zone. The serious fire Abnormal Procedures (Serious Station Fire or Serious Control Room Fire) would not be entered unless a fully developed fire occurs in an area that contains safe shutdown equipment.
The operator-may elect to trip the plant without entering either of the serious fire l
procedures.. Actions during such a shutdown would be governed by the reactor trip Emergency Procedure.
Up to this point none of the procedures require the operators-to trip offsite power, although the procedures cover how to respond 4
to an inadvertent or intentional loss of offsite power.
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If a fire progresses to the point where the damage from the fire is affecting the ability to safely shut down the plant, one of the two serious fire Abnormal Procedures is entered.
It is important to note that the threshold l
for entering these procedures is high.
Specifically, A fire outside the Control Room or Cable Spread Room, which is l
causing or has the potential to cause a loss of safe shutdown j
functions.
A Control Room or Cable Spread Room fire requiring prolonged evacuation of the Control Room, such that the plant shutdown cannot be controlled from the Control Room
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For the Serious Station Fire, the procedure provides instructions for the J
operator to shut down with or without offsite power because offsite-power may not be available. The operator is not instructed to trip offsite power if it is available, but the procedure states that if the fire is extremely serious and plant safety systems are being adversely affected by the fire, the Shift Supervisor may place the unit in a hot standby condition, and place the unit in a loss of offsite power condition at any time.
In the case of a serious Control Room or Cable Spread Room fire requiring prolonged Control Room evacuation, the Serious Control Room Fire procedure requires the reactor operators to trip offsite power prior to evacuating the control room.
Both the symptoms of procedure entry and discussion within the procedure emphasize that this procedure is only used when an extremely serious
Dohkat Nurber'50-346
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. Lic:nss Nu;ber NPF-3 Serial Number 1772' Attachment-li Page 3 fire in the Control Room or Cable Spread Room requires a prolonged Control Room evacuation.- The guidance for the operators to trip offsite power upon
- entering this-procedure is based on the following premises:
The fire severity is extreme and damage is occurring to safe shutdown equipment.
The likelihood of continued offsite power availability relative to the possibility of adverse impact to safe ~
shutdown equipment is low.
The procedure addresses the situation where the emergency diesel generator associated with the protected train is inoperable, assuring that the redundant emergency diesel generator can be made available to support safe shutdown.
The extreme severity of the fire causing the use of this-procedure is such that operator actions should be limited to those required to place the plant in a known and analyzed safe condition prior to proceeding to safe shutdown. After the Control Room has been L
. evacuated, the operators have a limited ability to identify and L
diagnose the numerous potential spurious actuations which could occur if power to non-safe shutdown equipment was not interrupted by tripping offsite power.
-r In summary, the use of of fsite power to support post-fire safe shutdown at Davis-Besse follows a phased approach using procedures which encourage the use of offsite power for all fire scenarios except those so severe that failure to trip-offsite power will place the plant into an unsafe and/or unanalyzed configuration.
Placing the-plant in an intentional loss of offsite power condition during a fire is proceduralized, as is the case where offsite power is not available for other reasons. Furthermore, the post-fire operator response is consistent vith the response for similar events not caused by fires, minimizing the possibility of operator error. The vide range of damage possibilities from a fire dictates this phased approach that relies heavily on operator assessment of the specific situation.
SUMMARY
Toledo Edison believes that the above approach is in compliance with fire protection regulatory requirements and guidance.
Specifically, NRC Inspection and Enforcement Manual Inspection Procedure 64100 states in part, "To simplify post fire shutdown procedures, some licensees may purposely open the offsite power breaker (s), thereby placing the plant electrical and mechanical systems in a known configuration." In addition, by utilizing offsite power whenever possible, without adversely affecting plant safety, to support post-fire safe shutdown, the' Davis-Besse approach is consistent with the concept of providing plant operators with adequate depth in the availability of safety-related support systems, an important general safety consideration. A voluntary loss of offsite power is a last resort during extremely serious and complex fire scenarios.
In these limited cases, tripping offsite power protects safe L
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Docket Number;50-346-s
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Lic::.ndo Noaber NPF-3.
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'shutdowniequipment and< puts the plant into a predetermined. safe, and analyzed ~
.This procedural requirement minimizes the possibility:of
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operator error', maximizes'the effectiveness of available on-shift operations.
personnel,4 andsis-consistent with both fire protection and~generel plant.
safety regulatory guidance, i
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.~ Dockst Nu;ber 50-346 ficinsh Nu b;r NPF-3 Serial Number 1772 Page 1 Suggested Changes to the Draft Fire Protection SER The submittals. referenced in the draft SER did not include a November 22, 1989 letter (Serial No._1735) that discussed the approach taken on protection of equipment against the effects of inadvertent fire suppression system actuation. The November 22, 1989 letter, the recent February 16, 1990 letter (Serial No. 1757) and this submittal should be added to the references listed in the._ final SER.
The following items are additional comments on the draft SER listed in the order of the SER text. The page number and paragraph number (starting with the first full paragraph on each page) are provided to help identify the location where the comment applies, i
Page 2, Para. 2 The seventh line of this paragraph lists several letters submitted by Toledo Edison for input to the SER. The document dated as June 28, should be listed as July 28, 1989.
E Page 9, Para. 3 The third line notes that the "... computer room valls inside the Control Room area... " are two-hour fire-rated. The Fire Hazards Analysis Report was the reference for this information. A downgrade of the computer room valls to a one-hour rating has been made due to the HVAC duct penetrations in the valls that do not have two-hour fire-rated damper installations. The fire load in the Computer Room (17,000 BTU /Ft ) can be adequately contained by a one hour 2
rated barrier.
t Page 30, Para. 2 The seventh line states that the pre-fire plans "... reflects the revised safe shutdown methodology...". This statement reflects an earlier pre-fire plan version that has now been streamlined to facilitate operator use as described in a letter dated May 27, 1987 (Serial No. 1361).
The current pre-fire plans do not contain the safe shutdown methodology because the fire brigade is composed entirely of Operations personnel who are familiar with plant equipment and its safety significance.
The two serious fire procedures utilized by plant operators contain the safe shutdown methodology. The operators involved in safe shutdown vill be in constant communication with the fire brigade to coordinate any necessary actions involving both groups.
Page 30, Para.1 and Page 32, Para. 3 Toledo Edison plans to utilize the portable fire detection system in the three locations that were identified as requiring the immediate assembly of the fire brigade. Each room vill have a separate channel, with a message that
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Dock 3t Humber.30-346 ei" <.:Lic:nsa Nu ber NPF-3 Serial Number-1772 -
'fage'2 specifically-instructs the Control Room-to assemble the fire brigade. An alarm from the portable fire detection system (s), would be the basis of the immediate. assembly of-'the fire brigade. The fixed detection system alarms in the Control Room are from multiple zones and could result in unnecessary assembly of the fire brigade.
For this reason, if the portable detection system is operable, the fire brigade vill not be assembled for a single (multizone) alarm from the fixed detection system. When the portable fire detection system (s) is inoperable a continuous fire watch vill be established in the' room (s) or the fixed detection systems vill be the basis for immediate assembly of the fire brigade. Toledo Edison requests that the SER be revised to reflect this approach.-
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