ML18010A506
| ML18010A506 | |
| Person / Time | |
|---|---|
| Site: | Harris  |
| Issue date: | 01/16/1992 |
| From: | Vaughn G CAROLINA POWER & LIGHT CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NLS-92-007, NLS-92-7, NUDOCS 9201240090 | |
| Download: ML18010A506 (21) | |
Text
ACCELERATED DI '7RIBUTION DEMONST TION SYSTEM 4
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I REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)
ACCESSION NBR:9201240090 DOC.DATE: 92/01/16 NOTARIZED: NO DOCKET FACIL:50-400 Shearon Harris Nuclear Power Plant, Unit 1, Carolina 05000400 AUTH.NAME AUTHOR AFFILIATION VAUGHN,G.E.
Carolina Power 6 Light Co.
RECIP.NAME RECIPIENT AFFILIATION Document Control Branch (Document Control Desk)
SUBJECT:
Provides response to NRC station blackout SE as applicable to plant. Concurs w/staff recommendations for most of remainining SE items.
DISTRIBUTION CODE:
A050D COPIES RECEIVED:LTR ENCL SIZE:
TITLE: OR Submittal: Station Blackout (UST A-44) 10CFR50.63, MPA A-22 D
NOTES:Application for permit renewal filed.
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A RECIPIENT ID CODE/NAME PD2-1 PD INTERNAL: ACRS NRR PD2-4PM TAM NRR/DST/SELB NRR/DST/SRXB8E EXTERNAL: NRC PDR COPIES LTTR ENCL 1
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1 RECIPIENT ID CODE/NAME MOZAFARI,B.
AEOD/DSP/TPAB NRR/DET/ESGB 8D NRRJ3 LB8D1 G
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NSIC COPIES LTTR ENCL 1
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NOTE TO ALL"RIDS" RECIPIENTS:
A D
D PLEASE HELP US TO REDUCE WASTE! CONTACT THE DOCUMENT CONTROL DESK, ROOM Pl-37 (EXT. 20079) TO ELIMINATEYOUR NAMEFROM DISTRIBUTION LIS15 FOR DOCUMENTS YOU DON'T NEED!
TOTAL NUMBER OF COPIES REQUIRED:
LTTR 17 ENCL 17
Carolina Power &Light Company P.O. Box 155t ~ Raleigh, N.C. 27602 G. E. VAUGHN Vice President Nuctear Servkes Department JAN18 l38P.
SERIAL:
NLS-92-007 10CFR50.63 United States Nuclear Regulatory Commission ATTENTION:
Document Control Desk Washington, DC 20555 SHEARON HARRIS NUCLEAR POWER PLANT DOCKET NO. 50-400/LICENSE NO. NPF-63
RESPONSE
TO NRC STATION BLACKOUT SAFETY EVALUATION Gentlemen:
The purpose of this letter is to provide Carolina Power
& Light Company's (CP&L) response to the NRC's Safety Evaluation (SE), dated December 11,
- 1991, regarding the Station Blackout (SBO) Rule (10CFR50.63) as applicable to the Shearon Harris Nuclear Power Plant (SHNPP).
The SE contained a number of recommendations and requested CP&L's confirmation of the resolution of these recommendations.
The enclosure to this letter provides CP&L's response to each of the recommendations.
CP&L disagrees that the required coping duration for SHNPP is eight hours for the reasons stated in our responses to SE Sections 2.1 and 2.2.5.
CP&L concurs with the Staff recommendations for most of the remaining SE items.
Should the Staff disagree with the response to SE Sections 2.1 and 2.2.5, then CP&L requests a meeting with the Staff to resolve the issues'P&L received the NRC SE on December 16, 1991.
In accordance with the schedular requirements of the SBO Rule, CP&L will complete the items necessary to meet 10CFR50.63 no later than December 16, 1993.
Given this schedular requirement, we request NRC approval of our position as soon as practicable.
Should you have any questions regarding this submittal, please contact Mr. S.
D. Floyd at (919) 546-6901.
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E IJ ENCLOSURE Page 1
SHEARON HARRIS NUCLEAR POWER PLANT DOCKET NO. 50-400/LICENSE NO. NPF-63
RESPONSE
TO NRC STATION BLACKOUT SAFETY EVALUATION SE Section 2.1 NRC Recommendation:
The Licensee should have an analysis showing EDG reliability statistics for the last 20, 50 and 100 demands in the documentation supporting the SBO submittal.
The licensee should select an EDG target reliability of 0.975 or resubmit its SBO analysis based on a required coping duration of eight hours rather than four hours.
CP&L Response:
CP&L performed an analysis showing EDG reliability statistics for the last 20, 50 and 100 demands utilized for determination of the coping duration.
The Nuclear Management and Resources Council, Inc.
(NUMARC) criteria for selection of either the 0.95 or 0.975 criteria is based on meeting an of the three evaluation criteria in Section 3.2.4 Ste Part 1
of NUMARC 87-00.
Based upon our review of the data, we had the option of selecting either 0.95 or 0.975, since SHNPP meets all three of the criteria.
That evaluation is included with the analysis maintained in the supporting documentation.
The second part of the NRC recommendation deals with the issue of the coping duration.
The appropriate classification for the off-site power design characteristic is the P2* value indicated in CP&L's original submittal.
The three issues of contention in this determination involve the extremely severe weather (ESW) classification, the applicability of pre-hurricane shutdown requirements, and the independence of off-site power (I) classification.
These three issues are addressed below.
ESW Classification Table 3-2 of NUMARC 87-00, "Guidelines and Technical Bases for NUMARC Initiatives Addressing Station Blackout at Light Water Reactors,"
notes that the data has not been ver fied for. accuracy.
Question 17 from NUMARC 87-00, "Supplemental Questions/Answers and Major Assumptions",
dated December 27, 1989, notes that site-specific data may be utilized, but is subject to review by the staff.
The site-specific data utilized by CP&L is from staff-analyzed data included in the SHNPP FSAR.
During a telephone conversation with the NRC staff on March 8,1991, CP&L requested information on the basis for the NRC-generated values noted in Table 3-2.
At that time, it was indicated that the staff would consider our information. If the staff finds the values indicated in the FSAR to be unacceptable, then we request that the NRC provide CP&L with the data utilized in development of Table 3-2 to allow validation of that information.
The Science Applications International Corporation (SAIC)
Technical Evaluation Report (TER) also questions if weather data since 1978 would change our assessment of ESW category.
The SHNPP general site area has not experienced winds of hurricane force due to a tropical storm since 1978.
Therefore, our previous assessment of ESW category is unchanged.
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ENCLOSURE Page 2
Pre-Hurricane Shutdown Re uirements CP&L also differs with the SAIC TER discussion concerning credit for hurricane readiness procedures.
The basis for that discussion focuses on issues that are not supported by the NUMARC 87-00 documentation.
The first is an implication that a plant may not be an ESW 3 plant and in turn take credit for the hurricane readiness procedures.
The ESW factor is based on the expected frequency of storms with wind velocities greater than or equal to 125 mph.
The threshold value for a hurricane is 74 mph.
The utilization of the hurricane readiness procedures is related to the plant being subject to the risk of a hurricane-induced loss of off-site power (LOOP).
The fact that the plant has not recorded hurricane force winds does not preclude the possibility of one occurring, or imply that the plant is not designed to withstand one.
The SHNPP off-site power system was designed for 90 mph winds as part of the design criteria.
The fact that NUMARC 87-00, Tables 3-5b and 3-6b include credit for those procedures under the ESW 3 columns would contradict an assumption that ESW 3 plants could not be considered hurricane affected plants.
I Classification Relative to SHNPP's independence of off-site power classification (I Group),
based on the NUMARC methodology, the site meets the requirements of the Il/2 classification.
Credit was not taken in the analysis for disconnecting the generator links to provide a "preferred alternate source" of off-site power to the emergency'uses.
An explanation of the basis is included below:
NRC Regulatory Guide (RG) 1.155 describes a means acceptable to the NRC staff for meeting the requirements of 10CFR50.63.
As indicated in Section C of RG 1.155, NUMARC 87-00 also provides guidance acceptable to the staff for meeting these requirements.
Section 3 of NUMARC 87-00 describes a process for determining required coping duration category.
Part 1.D of Section 3 is used to evaluate independence of the off-site power system (I Group).
The three criteria identified in Part 1.D and SHNPP's position with respect to those criteria is as follows:
Criterion A All off-site power sources are connected to the unit's safe shutdown buses through (1) one switchyard, or (2) two or more electrically connected switchyards.
SHNPP Position:
Yes.
SHNPP has a single 230kv switchyard consisting of two electrically connected buses.
Criterion B(1):
The normal source of AC power is from the unit main generator and there are no automatic transfers and one or more manual transfers of all safe shutdown buses to preferred or alternate off-site sources.
SHNPP Position:
No.
The normal source of power is from the main generator but there is an automatic fast bus transfer of both trains to their respective Start-up Transformers (SUTs),
the "preferred" off-site power source (SHNPP FSAR Section 8.3.1.1.2.4).
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ENCLOSURE Page 3
Criterion B(2):
The normal source of AC power is from the unit main generator and there is one automatic transfer and no manual transfers of all safe shutdown buses to one preferred or one alternate off-site power source, SHNPP Position:
No.
The normal source of power is from the main generator with each safe shutdown division transferring to its own "preferred" off-site power source.
These two "preferred" power sources are independent and designed to minimize the likelihood of a simultaneous failure.
Therefore, if the automatic transfer of one safety bus failed due to a breaker or transformer, then the automatic operation of the redundant and independent safety bus, breakers and transformer is credited.
The transformers in question are not separate windings on a single transformer as is common in many nuclear power plant switchyard configurations, but are two separate transformers that are approximately 150 feet apart from each other.
These transformers are noted in FSAR Figure 8.2.1-8 and the separation features are discussed in FSAR Section 8.2.1.3.
Based on the NUHARC 87-00 criteria, SHNPP is assigned to the Il/2 group.
Utilizing the criteria of RG 1.155, Table 5, the first criterion results in an I category of I2 or I3, as SHNPP has a single 230kv switchyard consisting of two electrically connected buses.
The normal source of power is from the main generator.
Statement 2a under the I3 Category is not applicable to SHNPP as there is an automatic fast bus transfer of both trains to their respective
- SUTs, the "preferred" off-site power source.
With respect to the second part of Statement 2a; while there is an automatic transfer of the safe shutdown buses, the transfer is to two separate preferred sources, rather than one.
This transfer is consistent with or actually superior to the description given under the I2 Category, for Question 2.
The same I group classification will be generated for SHNPP using either the NUMARC 87-00 criteria or Table 5 of Reg Guide 1.155.
The SHNPP Off-Site Power Source configuration meets the Il/2 category and 10CFR50 Appendix A, Criterion 17.
The following citation is taken from Section 8.3.1 of NUREG-1038, "Safety Evaluation Report Related to the Operation of Shearon Harris Nuclear Power Plant, Units 1 and 2,"
dated November 1983:
"The Shearon Harris Nuclear Power Plant is connected to the CP&L transmission grid by six 230kV transmission lines.
These lines come from five different substations and will approach the plant from different directions.
As these lines enter the plant area, four of the six lines share a common corridor; however, the physical separation between the lines is such that no single event (such as a tower falling or a line breaking) can simultaneously cause the failure of more than one circuit.
Thus, at least two separate and independent circuits from the transmission network
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ENCLOSURE Page 4
are available to supply off-site power to the Shearon Harris Nuclear Power Plant.
A third source of power to each emergency bus can be made available in approximately eight hours by disconnecting the generator links, and thus backfeeding through the unit auxiliary transformer.
This exceeds the requirements of GDC-17 and is acceptable."
While both safety buses do not transfer to a single source nor have a
second transfer to an alternate
- source, the transfer to inde endent and redundant sources.
Due to the high degree of divisional redundant capabilities and the "breaker and a half" arrangement of the switchyard, CP&L considers this arrangement to be superior to that described in the SAIC TER. If normal off-site power is lost and the transfer to one of the SUTs fails, there is no need for a second major transfer, manual or automatic (with the potential for mechanistic failure), since a complete redundant bus and related train of equipment are powered and immediately available.
Although the pre-hurricane requirements were not addressed in the NRC recommendations, the Safety Evaluation (SE) and the TER stated that the off-site power design characteristic of SHNPP was pending demonstration of compliance with the pre-hurricane shutdown requirements of NUMARC 87-00, Section 4.2.3.
In our letter of March 3,
- 1989, we indicated that we will satisfy the pre-hurricane shutdown requirements with the exception of start and load testing the EDGs to prepare for the onset of a hurricane.
CP&L requests an exemption from this requirement due to conflicts with post operating maintenance requirements imposed by Technical Specifications which would render the diesels inoperable for some duration.
Summary of CP&L Position:
CP&L maintains that the Shearon Harris Nuclear Power Plant is a four-hour coping duration plant with an EDG Reliability Factor of 0.95.
CP&L requests that, the NRC provide to CP&L what the staff requires for review and approval of the plant-specific ESW data and provide CP&L with the basis for NUMARC Table 3-2 so that we may validate and/or resolve variances with the plane-specific data.
We request an exemption from the pre-hurricane shutdown requirements to start and load test. the EDGs to prepare for the onset of a hurricane.
We also request that the NRC reevaluate and reclassify the independence of the off-site power (I) classification in light of the clarification we have provided to the SAIC TER.
SE Section 2.2 NRC Recommendation:
The licensee should verify that the battery calculations consider a
design margin of 10 to 15 percent as recommended in IEEE-Standard
- 485, and that the battery room temperature would never be lower than 70'F prior to an SBO event.
ENCLOSURE Page 5
CP&L Response:
An SBO Battery calculation was performed prior to the initial SBO submittal, considered a 15 percent design margin when using normal operating loads for the inverter.
The total battery capacity margin, when the SBO profile incorporated those normal operating loads for the
- inverter, was calculated to be greater than 30 percent.
It should be noted however, that the 15 percent margin, as stated in IEEE 485-1983 is to consider growth and less than optimal operation of the batteries.
For a mature plant battery load profile, design margin does not have to be considered when evaluating the adequacy of an existing system since the loads are known and the batteries are in a controlled environment.
Summary of CP&L Position:
The actual battery design margin available will be addressed in the plant design calculations and may vary from the 10 to 15 percent that is recommended based on that analysis.
An existing plant procedure requires that the battery room temperature be checked every 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> to verify that the room temperature does not exceed the Technical Specification maximum limit of 85'F.
This procedure will be modified to verify that the room temperature is not less than 70'F or more than 85'F.
SE Section 2.2.3 NRC Recommendation:
The licensee should provide assurance that the area enclosing the PORVs is habitable.
CP&L Response:
The value of 150'F noted for the main steam tunnel in CP&L's March 30, 1990 submittal does not reflect the actual temperatures anticipated.
It reflects a maximum bounding value determined by the engineering judgement utilized during identification of the Dominant: Areas of Concern for equipment operability.
Based on this value, there were no equipment operability concerns in the main steam tunnel (Section 7.2.4 of NUHARC 87-00).
In addressing the response procedures (Section 4 of NUMARC 87-00), consideration was given to the actual temperature that might be expected and the affect on personnel involved in the operation of the PORVs.
Based on that review and discussions with Operations personnel, guidance was provided on cautions to be taken related to entry to the main steam tunnel. It should be noted that the use of the Main Steam PORVs facilitates the planned cooldown and minimizes lifting of the Main Steam Safety Relief Valves.
While it is more desirable to use the PORVs to remove the decay heat and to cooldown the RCS during the four-hour coping period, the safety relief valves could be used to remove decay heat if the PORVs became inoperable.
If habitability conditions do not permit entry to the main steam tunnel, the plant could maintain temperature and pressure by use of the safety relief valves.
In addition, due to the nature of the hydraulic accumulators and the valve operation, constant attention by the auxiliary operator (and full
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ENCLOSURE Page 6
time occupancy in the main steam tunnel) is not required.
Only periodic entries may be required for use of the Main Steam PORVs.
Summary of CP&L Position:
CP&L does not anticipate habitability concerns for operation of the Main Steam PORVs.
In the unlikely event that existing plant procedures prohibit entry into the steam tunnel due to habitability considerations, an alternate means of removing decay heat will be implemented for the remaining portion of the SBO four-hour coping period.
SE Section 2.2.4.1 NRC Recommendation:
The licensee should reevaluate the control room temperature rise utilizing.an initial temperature no lower than the maximum allowed by the Technical Specification or the administrative procedures, and use conservative values for personnel heat load as described in the SAIC TER for the heat-up calculation.
The licensee should provide a step in the SBO procedure to open the control room cabinet doors within 30 minutes of the onset of an SBO.
CP&L Response:
The values noted in the SAIC TER of 111'F and the initial temperature of 75'F are not related.
SAIC requested information on which temperature could be assumed in normal day-to-day operation and 75'F was noted, as it is the nominal control room temperature setting.
We are using the Technical Specification value of 85'F.
The results of that calculation indicate that the control room will remain below 120'F utilizing 85'F as a starting temperature.
The SAIC TER questioned the number of people assumed in the control room.
The minimum shift complement is seven individuals.
The analysis assumed that the Auxiliary Operators were assigned duties outside of the main control room during SBO.
A lesson learned from TMI was to limit access to the control room during an emergency.
Therefore, the calculation assumed that only the operating staff on shift were permitted in the control room.
We have revised the calculation to reflect ten individuals.
The SAIC TER also indicated that the heat load for each person in the control room was non-conservative.
The heat load used by CP&L was based on the sensible heat, not the total heat sensible and latent
, for a man in light bench work in a factory.
The source of the data was Table 18, Page 26.21, ASHRAE Handbook, 1985 Fundamentals.
The personnel heat load recommended for use by SAIC in the TER exceeds any sensible heat load in Table 18 for vigorous activities.
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ENCLOSURE Page 7
Summary of CP&L Position:
CP&L revised the control room loss of.HVAC calculation with the previously assumed 85'F initial temperature and ten individuals in the control room.
The sensible heat load per person remained 400 BTU/Hr.
The calculation indicates that the temperature will remain less than 120'F.
We will provide a step in the SBO procedure regarding the opening of the control room cabinet doors within 30 minutes of the onset of an SBO.
SE Section 2.2.4.2 NRC Recommendation:
The licensee should perform a heat-up analysis using a conservative value for the inverter load to ensure that the calculated peak temperature in the invorter room is within the limits described in NUMARC 87-00 for equipment operability and personnel habitability.
CP&L Response:
The inverter room temperature was calculated as described in CP&L's March 30, 1990 submittal to document our engineering judgement that the room was not a dominant area of concern.
That calculation is available in the documentation supporting our submittal and the heat values were derived from an existing analysis.
The results of the calculation for the inverter room indicate the expected temperature rise is low due to (1) the lack of other equipment located within that room that would be powered during the SBO event and (2) the size of the room.
A sensitivity analysis was performed on the original calculation and it was determined that even when the inverter heat load was increased by a factor of four (from 1600 watts to 6400 watts),
the inverter room temperature would not exceed 120'F.
Summary of CP&L Position:
The inverter room was reviewed and it was determined that this room was not a dominant area of concern, based on the NUMARC criteria and the sensitivity calculation performed.
SE Section 2.2.5 NRC Recommendation:
The licensee should implement a procedural change or design modification for the isolation valves of the penetration X-74, list these valves in the appropriate procedure, and identify the actions necessary to ensure that they are fully closed during an SBO event.
The valve closure should be confirmed by position indication (local, mechanical,
- remote, process information, etc.).
This information should also be included with the other documentation that is to be maintained by the licensee in support of the SBO submittals.
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CP&L Response:
As discussed in a March 8, 1991 conference call and noted in additional information forwarded to the staff on April 5,
- 1991, the valve indicated (2MD-V77SB-1) can be manually closed or confirmed closed, and that information has already been provided in the guidance to the procedure changes required.
Consistent with the response to Question
- 102, the SBO procedures will not instruct the operators to close this valve in the event of an SBO as noted in the NRC recommendations, as that would probably prove unnecessary.
The procedures will provide the guidance on manual closure of this valve should the need to establish containment integrity consistent with SBO requirements occur.
This information is available and will be maintained with the documentation supporting our submittal.
Summary of CP&L Position:
d Valve 2MD-V77SB-1 will be utilized for containment isolation of the containment sump pump discharge through penetration X-74.
Through the appropriate procedure, this valve will be locally closed or confirmed closed if containment isolation is required.
CP&L requests that the NRC staff either provide concurrence with this aspect of containment integrity or provide clarification on how this does not meet the requirements of 10CFR50.63(a)(2) and Regulatory Guide 1.155.
SE Section 2.3 NRC Recommendation:
Although procedure training was not'pecifically identified as an NRC recommendation, the SE and TER identified the following requirement:
"The staff expects the licensee to implement appropriate training to ensure an effective response to an SBO."
CP&L Response:
CP&L will provide appropriate training as part of the procedure revisions necessary to ensure an effective response to an SBO.
Summary of CP&L Position:
CP&L will ensure appropriate SBO procedure training is implemented.
SE Section 2.4 NRC Recommendation:
The licensee should include a full description of the proposed plant modifications in the documentation that is to be maintained by the licensee in support of the SBO submittals.
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ENCLOSURE Page 9
CP&L Response:
A description of plant modifications.to satisfy the 4-hour coping duration and enhance operator ability to perform required actions associated with an SBO event will be maintained with the applicable modification package.
Summary of CP&L Position:
No additional action is required on this issue.
SE Section 2.5 NRC Recommendation:
The licens~e, should verify that the SBO equipment is covered by an appropriate QA program consistent with the guidance of Reg Guide 1.155.
This evaluation should be documented as part of the documentation supporting the SBO Rule response.
CP&L Response:
CP&L will ensure that SBO equipment included in the descriptions of Appendix B to Reg Guide 1.155 will be included in an appropriate QA program and information related to that issue will be included in the documentation that is to be maintained in support of the SBO submittals.
Summary of CP&L Position:
Items identified, as noted above, will be added to an appropriate QA program.
SE Section 2.6 NRC Recommendation:
It is the staff's position that an EDG reliability program should be developed in accordance 'with the guidance of Reg Guide 1.155, Section 1.2. If an EDG reliability program currently exists, the program should be evaluated and adjusted in accordance with RG 1.155.
Confirmation that such a program is in place or will be implemented should be included in the documentation that is to be maintained by the licensee in support of the SBO submittals.
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ENCLOSURE Page 10
~r CP&L Response:
As noted in our previous submittals, CP&L is committed to utilizing the NUMARC 87-00 methodology for coping with a Station Blackout.
As noted in Table 1 of Regulatory Guide 1.155, Appendix D of NUMARC 87-00 provides an acceptable means for meeting the requirements of 10CFR50.63.
CP&L will ensure that an EDG reliability program is implemented utilizing the guidance of Appendix D to NUMARC 87-00.
Information related to that program will be maintained with the documentation supporting the SBO submittals.
Summary of CP&L Position:
CP&L will maintain an EDG reliability program consistent with NUMARC 87-00, Appendix D guidance.
(1466HNP )