ML20245A946
| ML20245A946 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom  |
| Issue date: | 04/17/1989 |
| From: | Hunger G PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 8904250458 | |
| Download: ML20245A946 (11) | |
Text
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10 CFR 50.63(c)(1) i PHILADELPHIA ELECTRIC COMPANY 2301 MARKET STREET P.O. BOX 8699 PHILADELPHIA PA.19101 (215)8414000 April 17, 1989 Docket Nos. 50-277 50-278 License Nos. DPR-44 DPR-56 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555
SUBJECT:
Peach Bottom Atomic Powcr Station Units 2 and 3 Response to 10 CFR 50.63, " Loss of All Alternating Current Power"
Dear Sir:
On July 21, 1988, the Nuclear Regulatory Commission (NRC) amended its i
regulations in 10 CFR 50. A new section, 50.63, was added which requires that each light-water-cooled nuclear power plant be able to withstand and recover from a station blackout (SBO) of a specified duration. Utilities are expected to have the baseline assumptions, analyses, and related information used in their coping evaluation available for NRC review.
It also identifies the factors that must be considered in specifying the station blackout duration.
10 CFR 50.63 requires that, for the station blackout duration, the plant be capable of maintaining core cooling and appropriate containment integrity.
10 CFR 50.63 further requires that each licensee submit the following infctmation.
1.
A proposed station blackout duration, including a justification for its selection based on the redundancy and reliability of the on-site emergency alternating current (AC) power sources, the expected frequency of loss of off-site power, and the probable time needed to restore off-site. power; 2.
A description of the procedures that will be implemented for station blackout events for the duration (as determined in 1 above) and for recovery therefrom; and 3.
A list and proposed schedule for any needed modifications to equipment and associated procedures necessary for the specified station blackout duration.
The NRC has issued Regulatory Guide 1.155, " Station Blackout," which describes a means acceptable to the NRC Staff for meeting the requirements of 10 CFR 50.63. Regulatory Guide (R.G.) 1.155 states that the NRC Staff has detennined that 8904250458 890417 dO PDR ADOCK 05000277 ig p
-Doc,ument.C:ntrol D:sk April 17, 1989 Page 2 the document issued by the Nuclear Utility Management and Resources Council. NUMARC 87-00, " Guidelines and Technical Bases for NUMARC Initiatives Addressing Station Blackout At Light Water Reactors," also provides guidance that is in large part identical to the R.G. 1.155 guidance and is acceptable to the NRC Staff for meeting the requirements of 10 CFR 50.63. Table 1 to R.G. 1.155 provides a cross-reference between R.G. 1.155 and NUMARC 87-00 and notes where the R.G. takes precedence.
Philadelphia Electric Company (PECo) has evaluated the Peach Bottom Atomic Power Station (PBAPS) in accordance with the requirements of the 5B0 rule using guidance from NUMARC 87-00, except where R.G. 1.155 takes precedence. The results of this evaluation are detailed below.
(Applicable NUMARC 87-00 sections are shown in parentheses.)
A.
Proposed Station Blackout Duration NUMARC 87-00, Section 3, was used to detemine a required coping duration category of four hours.
The following plant factors were identified in determining the proposed station blackout duration per NUMARC 87-00.
1.
AC Power Design Characteristic Group is P2 based on the following.
a.
Expected frequency of grid-related loss of off-site power (LOOP) events does not exceed once per 20 years (Section 3.2.1, Part 1A, p. 3-3);
b.
Estimated frequency of LOOP events due to extremely severe weather (ESW) places the plant in ESW Group 3 (Section 3.2.1, Part 18, p. 3-4);
c.
Estimated frequency of LOOP events due to severe weather (SW) places the plant in SW Group 2 (Section 3.2.1, Part IC, p 3-7); and d.
The off-site power system is in the II/2 (Section 3.2.1, Part ID, p. 3-10).
2.
The emergency AC (EAC) power configuration group is C based on the following (Section 3.2.2 Part 2C, p. 3-13).
a.
There are three shared EAC power supplies not credited as alternate AC power sources per station (Section 3.2.2, Part 2A, p. 3-15); and b.
One EAC power supply is necessary to operate safe shutdown equipment following a LOOP event per station (Section 3.2.2, Part 2B, p. 3-15).
NOTE:
A limited amount of operator actions are credited to initiate cross-ties between electrical power sources in order to justify a one out of three EAC configuration.
3.
The target Emergency Diesel Generator (EDG) reliability is 0.975.
a.
NUMARC 87-00, Section 3.2.4, provides the following criteria for detemining the target EDG reliability based on demand sample size.
.. g.
Document Control Desk April 17 1989 0
i Page 3 If the EAC Group is A, B, or C, and any of the following criteria are met, then the nuclear unit may select an EDG reliability target of either 0.95 or 0.975.
LAST 20 DAMANDS
>0.90 RELIABILITY.
LAST 50 DEMANDS
>0.94 RELIABILITY
- LAST 100 DEMANDS
>0.95 RELIABILITY A target EDG reliability of 0.975 is justified based on having a nuclear unit average EDG reliability for the last 100 demands greater than 0.95, consistent with NUMARC 87-00 Section 3.2.4.
. 4.
An alternate AC (AAC) power source will be utilized at the PBAPS which meets the criteria specified in Appendix 8 to NUMARC 87-00.. The AAC source is a Class 1E EAC power source which meets the assumptions in Section 2.3.1 of NUMARC 87-00.
The AAC power source.is available within one hour of the onset of the station blackout event and has sufficient capacity and capability to operate systems necessary for coping with a station blackout for the required SB0 duration of four hours to bring and maintain the plant in safe shutdown. An AC independent coping analysis was performed for the one hour required to j
bring the AAC power source in line.
The AAC. power source for the PBAPS utilizes the excess redundancy of the EAC configuration.. PBAPS has four EDGs shared between two units. For the purposes of station blackout, any one EDG can support sufficient loads to maintain.' safe shutdown conditions for both units.
. Depending on the EDG that is available as the AAC power source, a limited number of operator actions will be necessary to bring the EDG on line.
- Figure 1 illustrates the PBAPS electrical system one line diagram, while Figures'2 through 5 illustrate the loads that are directly powered from the various EDGs.-
.B.
Procedure Description l
Plant procedures have been reviewed and will be revised, if necessary, to meet the guidelines in NUMARC 87-00, Section 4, in the following areas.
1.
Off-site AC power restoration per NUMARC 87-00, Section 4.2.2; 1 -
a.
System Operation Division Procedure
" System Restoration following Complete Shutdown."
2.
Severe weather per NUMARC 87-00. Section 4.2.3.
a)
Create a new severe weather procedure to include the following actions.
-1.
Inspect the site for missile hazards and reduce such hazards.
-4 :
Document Control Desk April 17, 1989 7
Page 4 11.
Initiate emergency repairs, as needed..of Emergency Core Cooling Systems (ECCS) and other selected systems required to cope with a
. blackout.
iii. Demonstrate EDG operability prior to the arrival of a hurricane.
iv. Review station blackout procedures.
v.
Review operability of ECCS equipment.
-v1.
Place station batteries on EQUALIZE charge.
vii.-Suspend appropriate surveillance test procedures.
b)
Revise Emergency Response Procedure ERP-101 such that an " Alert" is declared in the event of.a hurricane warning that involves the station area.
Plant procedures have baen reviewed and changes necessary to meet NUMARC 87-00 will be implemented in the following areas.
1.
Station blackout response per NUMARC 87-00 Section 4.2.1.
a)
! Revise the station blackout procedure (SE-11) entry condition to state
" Loss'of both startup sources."
b)
Revise SE-11 to add an appendix of. valves that may require closure should containment isolation be required.
c)
Revise SE-11 to refer to the AC power restoration procedure.
d)-
Revise SE-11 to remove steps to open High Pressure Coolant Injection (HPCI) and Reactor Core Isolation Cooling (RCIC) pump room doors.
e)
Revise SE-11 to refer to a new System Operating (S0) procedure concerning maintenance of water inventory in the Condensate Storage Tank (CST) using makeup from Refueling Water Storage Tank (RWST). Torus Water Storage Tank, and Fire System.
f)
Revise SE-11 to address the location of portable lighting and security system keys.
j
.g)-
Revise SE-11 to refer to the loss of the control room ventilation procedure.
h)
Revise SE-11 to show tables for loading of EDGs as AAC power sources.
C.
Proposed Modifications and Schedule The AAC power source has the capacity and. capability to power the equipment
~
necessary to cope with an SB0 in accordance with NUMARC 87-00 Section 7 for the required coping duration detemined in accordance with NUMARC 87-00, Section 3.2.5.
L
Document Control Dnsk April 17, 1989
{
Page 5
{
1.
Condensate Iaventory For Decay Heat Removal (Section 7.2.1)
We have determined from Section 7.2.1 of NUMARC 87-00 that 92041 gallons of water are required for decay heat removal, accounting for system leakage, for four hours. The minimum permissible CST level per design criteria i
provides 135,000 gallons of water, which exceeds the required quantity for coping with a four hour station blackout.
No plant modifications or procedure changes are needed to utilize this water source.
2.
Class 1E Battery Capacity (Section 7.2.2)
A battery capacity calculation has been performed pursuant to NUMARC 87-00 Section 7.2.2, to verify that the Class 1E batteries have sufficient capacity to meet SB0 loads for one hour.
3.
Compressed Air (Section 7.2.3)
Air-operated valves relied upon to cope with an SB0 for four hours have sufficient backup sources independent of the preferred and blacked out unit's Class 1E supply to perform their required functions or fail in the safe position.
4.
Effects of Loss of Ventilation (Section 7.2.4)
The steady state ambient air temperature has been calculated for the following oominant areas of concern.
AREA TEMPERATURE 0
HPCI Pump Room 170 F 0
RCIC Pump Room 163 F Cable Spreading Room 128 F No equipment necessary for safe shutdown is found in the Steam Tunnel at the PBAPS, therefore it is not considered a dominant area of concern.
The assumption in NUMARC 87-00, Section 2.7.1, that the control room will 0
not exceed 120 F during an SB0 has been assessed. We have determined 0
that the P8MPS control room does not reach the 120 F during an SB0 and therefore is not a dominant area of concern. Note, however, that the 0
120 F limit is not reached in the PBAPS control room provided the operators take actions to provide supplemental cooling by removing selected ceiling tiles and stripping unnecessary control room electrical loads in accordance with Off Normal Procedure ON-115. " Loss of Main Control Room Ventilation."
Reasonable assurance of the operability of station blackout response equipment in the above areas has been assessed using Appendix F to NUMARC 87-00. The following procedure changes are required to provide reasonable assurance for equipment operability in the control room:
i
4 Document C:ntrol Dask April 17. "?9 7-Page 6 Procedure SE " Station Blackout" - Revise to reference procedure ON-115. " Loss of Main Control Room Ventilation."
5.
Containment Isolation (Section 7.2.5)
The plant list of containment isolation valves has been reviewed to verify that the valves which must be capable of being closed or that must be operated (cycled) under SB0 conditions can be positioned (with indication) independent of the preferred and black-out unit's AC power supplies. The following procedure change'is required to ensure that appropriate containment inttgrity can be provided under SB0 conditions:
Procedure SE " Station Blackout" - Revise to show the containment isolation valves that are required to be manually operated should containment isolation be required.
6.
Reactor Coolant Inventory (Section 2.5)
The AAC source powers the necessary make-up systems to maintain adequate reactor coolant system inventory to ensure that the core is cooled for the required coping duration.
The associated procedure changes identified in Parts A, B, and C above will be completed one year after the notification provided by the Director Office of Nuclear Reactor Regulation in accordance with 10 CFR 50.63(c)(3).
Very truly yours,
~
G. A.
unger, Jr.
Director Licensing Section Nuclear Support Division Attachment cc:
W. T. Russell, Administrator, Region I USNRC T. P. Johnson, USNRC Senior Resident Inspector T. E. Magette, State of Maryland J. Urban Delmarva Power J. T. Boettger, Public Service Electric & Gas H. C. Schweien, Atlantic Electric T. M. Gerusky, Commonwealth of Pennsylvania
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PBAPS UNITS : & 3 STATION BLACKOUT RESPONSE PBAPS STATION BLACKOUT LOADS FOR EDG 4-125 V BATTERY FNR MOVS M
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CHARGER 30003 ROOMCOOLERS Figure S
. - _ _ _ _ _ _ _ - _ _ _ _ _ - - _ _ _ _ _