1CAN048908, Forwards Addl Info Re Station Blackout Rule 10CFR50.63, Including Development of NUMARC-8700 to Provide Guidelines & Criteria for Meeting Requirements of Rule
| ML20245J576 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 04/13/1989 |
| From: | Tison Campbell ARKANSAS POWER & LIGHT CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| 1CAN048908, 1CAN48908, NUDOCS 8905040182 | |
| Download: ML20245J576 (9) | |
Text
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ARKANSAS POWER & LIGHT COMPANY P. O. BOX 551/LITTLE ROCK, ARKANSAS 72203/(501) 377 3525 April 13, 1989 T. GENE CAMPBELL Vice President - Nuclear ICAN048908 U. S. Nuclear Regulatory Commission Document Control Desk Mail Station P1-137 Washington, DC 20555
SUBJECT:
Arkansas Nuclear One - Unit 1 Docket No. 50-313 License No. OPR-51 Information Submittal for Station Blackout Rule, 10CFR50.63 Gentlemen:
On July 21, 1988, the NRC amended 10CFR50 to add a new Section 50.63 to require that light-water-cooled nuclear power plants be capable of withstanding a total loss of alternating current (AC) electric power for a specified duration and maintaining reactor core cooling during that period.
Section 50.63(c)(1) requires that each licensee submit the following information:
1.
A proposed station blackout duration used in determining compliance with the rule, including a justification for the selection; 2.
A description of the procedures that will be implemented for station blackout events for the above duration and for recovery therefrom; and 3.
A list and proposed schedule for modifications to equipment and associated procedures, if any, necessary to meet the requirements of the rule.
NUMARC-8700 has been developed which provides guidelines and criteria for meeting the requirements of the rule.
The NUMARC-8700 initiatives / procedures have been reviewed by the NRC staff and referenced in Regulatory Guide 1.155 as providing acceptable guidance to meet the rule.
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8905040182 890413 i
PDR ADOCK 05000313 P
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MEMBEA MtOOLE SOUTH UTILITIES SYSTEM
U. 5. NuclGar Regulatory Commission April 13, 1989 1CAN048908 I
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Arkansas Power and_ Light Company has chosen to utilize the NUMARC-8700 guidelines in our response to the station blackout rule.
Our information submittal required by 10CFR50.63(c)(1) follows the NUMARC generic response format for plants using alternate AC power and is found in Attachment 1.
Very truly yours, j
j V
i T. Gene Campbel TGC:lg Attachment I
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ATTACHMENT 1 l
Information Submittal for 10CFR 50.63 (Station Blackout Rule)
L A uansas Nuclear One-Unit 1 (1CAN048908)
On July 21,1988, 't he Nuclear Regulatory Commission (NRC) amended its.
regulations in 10 C.F.R., Part 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 blackcut (580) 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.
Sectioi. 50.63' requires that, for the station blackout duration, the plant be capable of maintaining core cooling and appropriate containment integrity.
Section 50.63 further requires that each licensee submit the following information:
~
1.
A proposed station blackout duration including a justification for the selectiun. based on the. redundancy and reliability of the onsite emergency AC power sources, the expected frequency of loss of offsite power,-and the probable time needed to restore offsite power; 2.
A description of the procedures that are planned to 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 SB0 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 C.F.R. 50.63.
Regulatory Guide (RG) 1.155 states that the NRC Staff has determined that NUMARC-8700, " 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 RG 1.155 guidance i
and is acceptable to the NRC Staff for meeting these requirements.
Table'1 1
to RG 1.155 provides a cross-reference between RG 1.155 and NUMARC-8700 and notes where the RG takes precedence.
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l Arkansas Power and Light Company has evaluated Arkansas Nuclear One, Unit 1 against the requirements of the 560 rule using guidance from NUMARC-8700 l
except where RG 1.155 takes precedence.
The results of this evaluation are detailed below. (Applicable NUMARC-8700 sections are shown in parenthesis.)
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ll' A.
Proposed Station Blackout Duration NUMARC-8700, Section 3 was used to determine a proposed SB0 duration of i
four hours.
The following plant factors were identified in determining the proposed station blackout duration:
1.
AC Power Design Characteristic Group is P1 based on:
a.
Expected frequency of grid-related LOOPS (Loss of Off-Site Power) does not exceed once per 20 years (Section 3.2.1, Part IA, p. 3-3);
b.
Estimated frequency of LOOPS due to extremely severe weather places the plant in ESW Group 1 (Section 3.2.1, Part IB,
- p. 3-4);
c.
Estimated frequency of LOOPS due to severe weather places the plant in SW Group 2 (Section 3.2.1, Part IC, p. 3-7);
d.
The offsite power system is in the 11/2 Group (Section 3.2.1, Part ID, p. 3-10).
2.
The emergency AC power configuration group is C based on: (Section 3.2.2, Part 2C, p. 3-13) a.
There are two emergency AC power supplies not credited as alternate AC power sources (Section 3.2.2, Part 2A, p. 3-15);
b.
One emergency AC power supply is necessary to operate safe shutdown equipment following a loss of offsite power (Section 3.2.2, Part 2B, p. 3-15).
3.
The target EDG reliability is 0.95, a.
A target EDG reliability of 0.95 was selected based on having a nuclear unit average EDG reliability for the last 100 demands greater than 0.95 consistent with NUMARC-8700, Section 3.2.4. The nuclear unit average EDG reliability exceeded each of the three criteria given in NUMARC-8700 (i.e., >0.90 for the last 20 demands, >0.94 for the last 50 demands, and >0.95 for +he last 100 demands).
4.
An alternate AC (AAC) power source will be utilized at ANO, Unit I which meets the criteria specified in Appendix B to NUMARC-8700.
The AAC source is an emergency AC power source which meets the assumptions in Section 2.3.1 of NUMARC-8700.
2
The AAC power source would, after modifications and procedure changes, be available within one hour of the onset of the station l
blackout event and would have sufficient capacity and capability I
to operate systems necessary for coping with a station blackout j
l for the required SB0 duration (four hours) in order to bring the plant to safe shutdown and to maintain that condition.
An AC independent coping analysis was performed for the one hour i
required to bring the AAC power source on line.
l ANO is a two unit site, each with two dedicated emergency diesel generators either one of which is capable of providing electrical I
power for accident mitigation and safe shutdown of the unit.
The l
AAC source for Unit 1 will consist of a cross-tie between the safety buses of Units 1 and 2 to enable powering Unit 1 minimum safe shutdown loads from either of the Unit 2 E0G's (station blackout is not assumed for both units).
Each of the Unit 2 EDG's 3
has sufficient capacity to operate necessary safe shutdown systems J
for both units and, with the AAC cross-tie, would have the 1
capability to provide power to either of the Unit 1 safety buses.
Therefore, the capability would exist for safe shutdown of both
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units, assuming a station blackout in Unit 1 concurrent with a l
single failure (including a failure of one E0G) in Unit 2.
{
Figure 1 provides a one-line diagram of this AAC power source.
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B.
Procedure Description
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i Plant procedures have been reviewed and modified, if deemed necessary, j
to meet the guidelines in NUMARC-8700, Section 4 in the following I
areas:
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1 AC power restoration per NUMARC-8700, Section 4.2.2:
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l a.
ANO Unit 1 Emergency Operating Procedure (OP 1202.01, Rev. 13) b.
Coordination of ANO Switchyard and AND Related Offsite
)
Transmission Equipment (Procedure OSP 011B) 2.
Severe weather per NUMARC-8700, Section 4.2.3.:
a.
ANO Administrative Procedure, (1000.119, Rev. 0)
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Plant Preparations for Tornado i
Plant procedures have been reviewed and changes necessary to meet I
NUMARC-8700 are planned to be implemented in the following areas:
1.
Station blackout response per NUMARC-8700, Section 4.2.1:
a.
ANO Unit 1 Emergency Operating Procedure (OP 1202.01) 3 l
2.
Procedure changes associated with any modifications required after assessing coping capability per NUMARC-8700, Section 7:
a.
ANO Unit 1 Emergency Operating Procedure (OP 1202.01).
b.
Other station procedures (surveillance, etc.) may require change, depending on the specific modifications installed.
C.
Proposed Modifications and Schedule The modifications required to utilize the AAC power source (see Figure'1) are:
1.
Cabling between each unit's safety buses.
2.
ANO Unit 1 switchgear modifications to accommodate this cross-tie.
3.
ANO Unit 2 switchgear modifications to accommodate this cross-tie.
The AND Emergency Operating Procedures for both units (OP 1202.01 and OP 2202.01) would require modification to align the breakers, shed load, and provide fcr coordination of activities between each units' operators.
Also required would be the procedural changes nccessary to re-align ANO Unit 1 EDG or off-site power when either becomes available.
Completion of the AAC cross-tie hardware modifications listed above are planned to be completed by the end of our refueling outages 1R10 and 2R8, currently projected to end on 10/23/91 and 4/11/91, respectively. Procedure changes are planned to be implemented by the end of the IR10 outage.
These projections principally are based on anticipated lead times for the necessary switchgear equipment. It should be noted that implementation could possibly occur later, deperding on the NRC assessment response or the actual rtart of 1R10 or 2R8.
D.
Coping Assessment for One Hour AAC As stated previously, the ANO AAC power source will be available within one hour of the onset of the station blackout event. The AAC source will have the capacity arsi capability to power the equipment necessary to cope with a SB0 in accordance with NUMARC-8700, Section 7 for the required coping duration determined in accordance with NUMARC-8700, Section 2.5 which, for ANO, consists of one hour in an AC-Independent state and t o e hours in an AAC configuration.
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N The results of the one hour AC Independent coping analysis and additional analyses which were performed to ensure acceptability of the i
proposed AAC power source for the required SB0 duration of four hcurs are as follows:
1.
Condensate Inventory For Decay Heat Removal (Section 7.2.1)
It has been determined from Section 7.2.1 of NUMARC-8700 that 56,804 gallons of water are required for decay heat removal for four hours.
The minimum permissible. condensate storage tank level per technical specifications provides 107,000 gallons of water.
which exceeds the required quantity for coping with a four hour station blackout.
2.
Class IE Batteries Capacity (Section 7.2.2)
A battery capacity calculation has been performed pursuant to NUMARC-870A, Section 7.2.2 to verify that the Class IE batteries have sufficient capacity to meet station blackout loads for one hour.
3.
Compressed Air (Section 7.2.3)
No air-operated valves are relied upon to cope with a station blackout for one hour.
4.
Effects of Loss of Ventilation (Section 7.2.4)
The calculated steady state ambient air temperature for the EFW pump room during a station blackout induced loss of ventilation is 131 F ("A" pump operation), assuming an open doorway.
With respect to the control room complex for PWR's, the assumption in NUMARC-8700, Section 2.7.1 that the control room will not exceed 120 F during a station blackout has been assessed.
The control room at Arkansas Nuclear One, Unit 1 does not exceed 120 F during a station blackout. Therefore, the control room is not a dominant area of concern.
For ANO Unit 1, HVAC is not provided in a station blackout.
NUMARC-8700 does not require HVAC to be powered from the AAC source when an existing machine is utilized for the AAC source.
HVAC systems serving the following dominant areas of concern are not available:
EFW pump room Primary makeup pump rooms Service water pump structure Control room Room 99 (DC electrical equipment)
Room 109 (DC electrical equipment) 5
o Reasonable assurance of the operability of station blackout response equipment in the above dominant areas has been assessed using Appendix F to NUMARC-8700 and/or the Topical Report as well as analyses previously performed.
The following procedure changes would be required to provide reasonable assurance for equipment operability:
ANO Unit 1 Emergency Operating Procedure, 1202.01 This procedure is planned to be modified to require opening of the control room cabinet doors that contain ^quipment to be relied upon in a station blackout and opening the EFW pump room door.
5.
Containment Isolation (Section 7.2.5)
The list of plant containment isolation valves has been reviewed to verify that valves which must be capable of being closed or that must be operated (cycled) under station blackout conditions can be positioned (with indication) independent of the preferred and blacked-out unit's Class IE power supplies.
No plant modifications and/or associated procedure changes were determined to be required to ensure that appropriate containment integrity can be provided under SB0 conditions.
6.
Reactor Coolant Inventory (Section 2.5)
The ability to maintain adequate reactor coolant system inventory to ensure that the core is cooled has been assessed for one hour.
The generic analyses listed in Section 2.5.2 of NUMARC-8700 were used for this assessment and are applicable to Arkansas Nuclear One Unit 1.
The expe',ted rates of reactor coolant inventory loss under SB0 conditione do not result in core uncovery in an 5B0 of one hour.
Therefo e, makeup systems in addition to those currently availabie under SB0 conditions are not required to maintain core cooling under natural circulation (including boiler-condenser boiling).
The modifications and associated procedure changes identified in Parts A, 6 and C above are planned to be completed by the end of our refueling outage IR10, currently estimated as 10/23/91, depending on actual date of 2R8 and 1R10 outages and on the regulatory assessment to be provided by the Director, Office of Nuclear Reactor Regulation in accordance with 10 C.F.R. 50.63(c)(3).
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