ML17262A740
| ML17262A740 | |
| Person / Time | |
|---|---|
| Site: | Ginna  |
| Issue date: | 01/30/1992 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML17262A739 | List: |
| References | |
| RTR-REGGD-01.155, RTR-REGGD-1.155 NUDOCS 9202050505 | |
| Download: ML17262A740 (22) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 ENCLOSURE 1
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION STATION BLACKOUT EVALUATION ROCHESTER GAS AND ELECTRIC CORPORATION R. E.
GINNA NUCLEAR POWER PLANT DOCKET NO. 50-244
1.0 INTRODUCTION
On July Pl, 1988, the Code of Federal Regulations, 10 CFR Part 50, was amended to include a
new section 50.63, entitled "Loss of All Alternating Current Power," (Station Blackout).
The Station Blackout (SBO) Rule requires that each light-water-cooled nuclear power plant be able to withstand and recover from an SBO of a specified duration.
The SBO Rule also requires licensees to submit information as defined in Part 50.63 and to provide a plan and schedule for conformance to the SBO Rule.
The SBO Rule further requires that the baseline assumptions,
- analyses, and related information be available for NRC review.
Guidance for conformance to the SBO Rule is provided by (1) Regulatory Guide (RG) 1.155, Station Blackout, (2) The Nuclear Hanagement and Resources
- Council, Inc.,
(NUHARC) 87-00, Guidelines and Technical Bases for NUHARC Initiatives Addressing Station Blackout at Light Water Reactors, and (3)
NUHARC 87-00 Supplemental guestions/Answers and Hajor Assumptions dated December 27, 1989, (issued to the industry by NUHARC on January 4, 1990).
To facilitate the NRC staff's (hereafter referred to as staff) review of licensee responses to the SBO Rule, the staff endorsed. two generic response formats.
One response format is for use by plants proposing to use an Alternate AC (AAC) power source and the other format is for use by plants proposing an AC independent response.
The gener'.c response formats provide the staff with a summary of the results from the licensee's analysis of the plant's SBO coping capability.
The licensees are expected to verify the accuracy of e20ZOSo o
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the results and maintain documentation that supports the stated results.
Compliance to the SBO Rule is verified by a review of the licensee's submittal, an audit review of the supporting documentation as deemed necessary, and possible follow-up NRC inspections to ensure that the licensee has implemented the appropriate hardware and/or procedure modifications that will be required to comply with the SBO Rule.
The licensee's responses to the SBO Rule were provided by letters from Robert C. Hecredy on April 17, 1989, March 30, 1990, and July 10, 1990, to Thomas E. Hurley; and on April 22, 1991, to Allen R. Johnson, of the U.S.
Nuclear Regulatory Commission.
The l'.censee's responses were reviewed by Science Applications International Corporation (SAIC) under contract to the NRC.
The results of the review are documented by an SAIC Technical Evaluation Report (TER) SAIC-91/6694, "R. E.
GINNA NUCLEAR POWER PLANT, STATION BLACKOUT EVALUATION," dated October 30, 1991 (Attachment 1).
- 2. 0 EVALUATION After reviewing the licensee' submittals and the SAIC TER, the staff concurs with the SAIC analysis and conclusions as identified in the SAIC TER (refer to Attachment 1 for details).
The staff findings and recommendations are summa-rized as follows:
2.1 Station Blackout Duration The licensee has calculated a minimum acceptable SBO duration of 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> based on the plant AC power design characteristic Group "P2," an emergency AC (EAC) power configuration Group "C," and a target Emergency Diesel Generator (EDG) reliability of 0.975.
The Group "C" EAC configuration is based on the site being equipped with two emergency ac power supplies, one of which is necessary to operate safe shutdown equipment following a LOOP.
The target EDG reliability was based on the R.
E. Ginna (Ginna) Plant having an average EDG reliability greater than 0.95 for the last 100 demands.
The "P2" grouping is based on an independence of offsite power classification of Group "I 1/2,"
a severe weather
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After reviewing the available information in the licensee s submittals, RG 1.155, NUMARC 87-00, and SAIC's TER, the staff agrees with the TER and the licensee's evaluation of a 4-hour SBO coping durat'.on.
Recommendation:
The target EDG reliability of 0.975 has been selected based on the demonstrated unit average EDG reliability for the last 100 demands.
The licensee should also evaluate, and include in the documentation to be retained by the licensee in support of the SBO submittal, the EDG reliability for the last 20 and 50 demands consistent with the criteria given in RG 1.155 and NUMARC 87-00.
2.2 Station Blackout Co in Ca abilit The licensee has proposed coping capability independent of an alternate AC power source for the SBO coping duration of 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> and recovery therefrom.
The characteristics of the following plant systems and components were reviewed to assure that the systems have the availability, adequacy, and capability to achieve and maintain a safe shutdown and to recover from an SBO for a
4-hour coping duration.
2.2.1 Condensate Inventor for Deca Heat Removal The licensee stated that 76,823 gallons of water are required for decay heat removal and cooldown during the 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> of an SBO event.
The minimum permissible condensate storage tank level, per TS, provides 22,500 gallons of water.
However, the licensee identified, per procedure ER-AFW.1, that three additional water sources (the 110,000 outside storage tank, city water, and the plant fire water system) will be available as supplemental water inventory.
Procedures will be revised to preclude confusion and delays in the use of these al ternate/supplemental water sources.
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Based on its review and the licensee's commitment to revise the appropriate procedures to utilize the alternate/supplemental water sources, the staff
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concludes that there is sufficient water supply to cope with an SBO event at the Ginna plant.
2.2.2 Class 1E Batter Ca acit The licensee originally provided battery siz'.ng calculations for 2 and 4
hours.
The original calculations showed that the battery capacity was insufficient to cope for a 4-hour SBO event.
Subsequently, the licensee rev'.sed its battery calculations by excluding some of the larger DC loads which are being removed from the safety-related batteries during the April 1991 outage.
The loads that are being removed are:
a.
Turbine DC lube oil pump from Battery A
b.
Air side generator seal oi l backup pump and two motor-operated valves on the circulating water pump discharge line from Battery B.
Based on the revised battery capacity calculations with the load changes, the staff agrees with the licensee that the batteries conform to the recommended guidance of IEEE-Std. 485-1987 and will have sufficient capacity to last for a 4-hour SBO duration.'.2.3
~dd 2'I The licensee stated that air-operated valves relied upon to cope with an SBO event can either be operated manually or have sufficient backup sources in-dependent of the preferred and Class 1E power supply.
Valves requiring manual operation or that need backup sources for operation are identified in plant procedures.
However, the licensee has not addressed the habitability of the areas where the valves are located
( i.e., turbine driven auxiliary feedwater pump flow control valves, atmospheric steam.dump valves, etc.) for assessing manual operation during an SBO event.
Therefore, the staff has not been able to conclude that the licensee will be able to operate these valves manually during an SBO event.
Recommendation:
The licensee should verify/ensure that the areas which house the above cited valves are habitable during an SBO event.
2.2.4 Effects of Loss of Ventilation The licensee has performed analyses to determine the effects of loss of ventilation in the control room, relay room, battery rooms A and B, turbine driven auxiliary feedwater pump room, and atmospheric steam dump valve area during an SBO event.
The staff's evaluation of the effects of loss of ventilation in each of these areas is provided below:
2.2.4.1 Control Room
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The licensee stated that the calculated peak temperature during an SBO event for the control room with the door open is 115.9'F which is below the guidance for the control room temperature limit described in NUMARC 87-00.
Consequently, the licensee concluded that reasonable assurance of equipment operability in the control room is provided; however, the licensee procedures will have to be revised to require operators to remove ceiling tiles and to open the door to the turbine deck.
To perform the heat-up analysis for the control room, the licensee did not conduct an estimation of heat loads generated from equipment components in the control room, instead, the licensee developed/conducted a test to measure the specific control room heat loads under operating conditions.
These heat loads were then used to calculate a time-dependent temperature.
However, the licensee has not provided the details of the test for the staff to review, therefore, the staff has not been able to conclude that the measured heat loads are accurate/conservative enough to be used in the heat-up analysis.
Also, during the course of its review, the staff's consultant reviewed the input parameters used by the licensee for the analysis and found that some non-conservat'.ve values were assumed for the in'.tial room temperature, outside temperature heat sink surface are'as, thermal conductivity, etc.
Based on its review, the staff agrees with its consultant's conclusion that the effect of these non-conservative input parameters on the control room final calculated peak temperature would be significant and that if the licensee were to use more conservative values for the input parameters, the final calculated peak temperature in the control room may exceed 120'F even with the door open.
Therefore, the staff has not been able to conclude that the above calculated peak temperature of 115.9'F for tPe control room is acceptable.
In addition, the licensee has not addressed the procedure which will require the operators to take action within 30 minutes during an SBO event to open instrument cabinet doors per the guidance described in NUHARC 87-00.
Recommendations:
The licensee should: I) reevaluate and provide the results for staff review of the temperature rise in the control room using a conser-vative initial temperature corresponding to the TS temperature limits or the maximum value allowed under administrative procedures, and using con-servative parameters as described in the SAIC TER for the heat-up calcula-tions. If the licensee's administrative procedures do not specify an operating temperature limit, the licensee should establish administrative procedures or revise existing procedures to maintain the control room temperature at or below the initial room temperature used in the heat-up
- analysis,
- 2) provide for staff review detailed information about the test performed to measure the heat loads in the control room and verify that these heat loads were correctly/conservatively
- measured,
- 3) have a procedure which will require the operators to take action within 30 minutes during an SBO event to open instrument cabinet doors per the guidance described in NUHARC 87-00, and 4) have a procedure to require operators to remove ceiling tiles and open the control room door to the turbine deck within 30 minutes during an SBO event.
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2.2.4.2 Rela Room and Batter Rooms A and B
The licensee stated that using the measured heat load obtained from tests (similar to the test conducted for the control room discussed above) the calculated peak temperatures with doors closed for the relay room and battery rooms A and B are 103'F, 107'F, and 106.2'F, respectively.
Consequently, the licensee concluded that reasonable assurance of equipment operability is provided in accordance with the guidance described in NUMARC 87-00.
Based on its review and concerns which are described for the control room above and are also applicable for these rooms, the staff has not been able to agree with the licensee that reasonable assurance of equipment operability in these rooms has been provided.
Recommendations:
The licensee should:
- 1) reevaluate and provide the results for staff review of the temperature rise
'.n the relay room and battery rooms A
and B using conservative initial temperatures, corresponding to the TS temper-ature limits or the maximum values allowed under administrative procedures, and using conservative parameters as described
'.n the SAIC TER for the heat-up calculations.
If the licensee's administrative procedures do not spec'.fy an operating temperature limit for each of these rooms, the licensee should establish administrative procedures or revise the existing procedures to main-tain the room temperatures at or below the initial room temperatures used in the heat-up analyses and 2) provide the detailed information about the tests performed to measure the heat loads in these rooms and verify that these heat loads were correctly/conservatively measured.
2.2.4.3.
Turbine Driven Auxiliar Feedwater AFW Pum Room The licensee stated that the calculated peak temperature for the AFW pump room is 145'F with doors open and is below the guidance of the temperature limit described in NUMARC 87-00 for equipment operability., Therefore, the licensee concludes that there is reasonable assurance of operability of SBO response equipment in the AFW pump room.
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During the course of its review, the staff's consultant performed an independent heat-up analysis for the AFW pump room with doors open.
The staff's consultant calculated a peak temperature of 152'F which '.s higher than that calculated by the licensee and exceeds the guidance of the temperature limit described in NUMARC.87-00.
Therefore, the staff has not been able to agree w'.th the licensee's conclusion that there is reasonable assurance of operabil'.ty of SBO response equipment in the AFW pump room.
Recommendations:
The licensee should: I) evaluate and provide results for staff review of the temperature rise in the AFW pump room using conservative assumptions (see SAIC's TER) and assess the effect of the higher temperature on the equipment required to respond to an SBO event in the AFW pump room,
- 2) establish/provide a procedure to open the AFW pump room door within 30 minutes from the onset of an SBO event, and 3) assess and confirm the habitability in the AFW pump room (see SE Section 2.2.3).
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2.2.4.4 Atmos heric Steam Dum Valve (ADV Area The licensee stated that the calculated peak temperatures for the ADV area are 186'F (with doors closed) and 178.9'F (with doors open).
However, the licensee has not addressed the assessment of the operability of equipment and the habitabi lity at the above temperatures in this area during an SBO event.
Recommendation:
The licensee should evaluate the operability of equipment and the habitability (see SE Section 2.2.3) at the above cited temperature in the ADV area during an SBO event.
2.2.5 Containment Isolation The licensee stated that the plant list of Containment Isolation Valves (CIVs) had been reviewed to verify that CIVs that must be operated under SBO condi-tions can be positioned, with indication independent of the preferred and Class 1E AC power supplies, and that no,modifications or procedure changes are
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necessary to ensure containment integrity can be obtained if it is needed under SBO conditions.
The licensee provided a list of CIVs and justification for exclusion per NUMARC 87-00 for each penetration.
Based on its review, the staff concludes that the CIV design and operation at the Ginna plant have met the intent of the guidance described in RG 1.155 and are acceptable.
2.2.6 Reactor Coolant Inventor The licensee stated that the abi lity to maintain adequate reactor coolant system inventory to ensure that the core is cooled has been assessed for 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />.
In a subsequent
- response, the licensee added that a plant specific simulation using the TREAT code was run for the projected SBO scenario.
The licensee provided excerpts from this analysis and stated that this transient was also evaluated with the MAAP 3.0B Revision 17 with similar results.
The licensee concluded that the expected rates of the reactor coolant inventory loss under SBO conditions do not result in the core being uncovered during a
4-hour SBO event.
The staff concurs with the licensee and SAIC TER that the core will remain covered and is cooled by natural circulation through reflux boiling.
The reactor coolant inventory evaluation was based on the guidance of NUMARC 87-00 of 25 gpm per reactor coolant pump seal leakage for pressurized water reactors.
The 25 gpm reactor coolant pump seal leakage was agreed upon between NUMARC and the NRC staff pending resolution of Generic Issue (GI) 23.
If the final resolution of GI-23 defines higher reactor coolant pump seal leakage rates than assumed for the RCS inventory evaluation, the licensee should be aware of the potential impact of this resolution on its analysis and actions addressing conformance to the SBO Rule.
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2.3 Procedures and Trainin The licensee stated that the plant procedures, SBO response guidelines, AC power restoration, and severe weather, have been reviewed and the changes necessary to meet NUMARC 87-00, Section 4, guideline will be implemented within 2 years after notification provided by the staff in accordance with 10 CFR 50.63 (c)(3).
The staff did not review the procedures or proposed procedure modifications.
The staff expects the licensee to maintain and implement these procedures including any others that may be required to ensure an appropriate response to an SBO event.
Although personnel training requirements for an SBO response were not specifically addressed by the licensee's submittal, the staff expects the licensee to implement the appropriate training to ensure an effective response to an SBO.
2.4 Pro osed Modifications The licensee did not identify any plant modifications to be required in order to cope with a 4-hour SBO duration.
However, modifications may be necessary to
'.mplement the actions and verifications described in the recommendations made
'.n this SE.
2.5 gualit Assurance and Technical S ecifications The licensee provided a copy of the list of equipment which is necessary to cope with as well as to recover from an SBO event.
The list shows most of the SBO response equipment to be safety related and therefore covered under a
qualified gA program.
However, the licensee did not specifically address the TS program for the SBO equipment.
The TS for the SBO equipment are currently being considered generically by the NRC in the context of the Technical Specification Improvement Program and remains an open item at this time.
However, the staff would expect that the plant procedures will reflect the
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appropriate testing and surveillance requirements to ensure the operability of the necessary SBO equipment.
If the staff later determines that TS regarding the SBO equipment
'.s warranted, the licensee will be notified of the implementation requirements.
Recommendation:
The licensee should verify that the SBO equipment
'.s covered by an appropriate gA program consistent with the gu'.dance of RG 1.155.
This evaluation should be documented as part of the documentation supporting the SBO Rule response.
2.6 EDG Reliabilit Pro ram The submittal did not specifically address the commitment to implement an EDG reliability program to conform to the guidance of RG 1.155, Position 1.2.
Recommendation:
It is the staff's position that an EDG reliability program should be developed in accordance with the guidance of RG 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.
2.8 Sco e of Staff Review The SBO Rule (10 CFR 50.63) requires licensees to submit a response containing specifically defined information. It also requires utilities "... to have baseline assumptions,
- analyses, and related information used in their coping evaluations available for NRC review."
The staff and its contractor (SAIC) did not perform a detailed review of the proposed hardware and procedural modifi-cations which are scheduled for later implementation.
- However, based on our review of the licensee's supporting documentation, we have identified the following areas for focus in any follow-up inspection or assessment that may be undertaken by the NRC to verify conformance with the SBO Rule.
Additional
'.tems may be added as a result of the staff review of the actions taken by the licensee in response to this SE.
a.
Hardware and procedural modificat'.ons, b.
SBO procedures in accordance with R.G. 1.155, Position 3.4, and NUMARC 87-00, Section 4, c.
Operator staffing and training to follow the identified actions in the SBO procedures, d.
EDG reliability program meets, as a minimum, the guidelines of RG 1.155, e.
Equipment and components required to cope with an SBO are incorporated in a gA program that meets the guidance of RG 1.155, Appendix A, and f.
Actions taken pertaining to the specific recommendations noted above in the SE.
3.0 CONCLUSION
S Based on the staff's review of the licensee's SBO submittals and the SAIC TER, the staff finds that the Ginna station does not conform with the SBO rule and the guidance of RG 1.155, and therefore recommends that the licensee reevaluate the areas of concern that have been identified in this SE.
Guidance for the licensee to review and implement the staff's recommendations is provided in RG 1.155, NUMARC 87-00 and the supplementary guidance (NUMARC 87-00 Supplemen-tary guestions/Answers; NUMARC 87-00 Major Assumptions) dated December 27, 1989, which was issued to the industry by NUMARC on January 4, 1990.
The staff's concerns that are identif'.ed in this SER should be addressed by the licensee, and a revised response submitted to the NRC within 60 days.
The licensee is expected to ensure that the baseline assumptions of NUMARC 87-00 are applicable to the R.E.
Ginna Nuclear Power Plant.
Also, the licensee is expected to document all analyses and related information, and verify that these are available for NRC review.
4.0 Attachment SAIC-91/6661, Technical Evaluation Report, R.
E. Ginna Nuclear Power Plant, Station Blackout Evaluation, October 30, 1991.
Princi al Contributor S.
K. Mitra, SELB/DST
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