ML20116E793
| ML20116E793 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs  |
| Issue date: | 09/27/1990 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20116D885 | List:
|
| References | |
| FOIA-96-237 NUDOCS 9608060125 | |
| Download: ML20116E793 (15) | |
Text
-. -.... - - -
4 t
l ENCLOSURE 1 i
CALVERT CLIFFS NUCLEAR POWER PLANT STA PORT l
1.0 INTRODUCTION
I On July 21, 1968,.the Code of Federal Regulations 10CFR Part 50, was amended to l
include a new Section 50.63, entitled " Loss of All Alternating Current Power,"
i (Station Blackout). The station blackout (SBO) rule requires that each'Ifght-l water-cooled nuclear power plant be able to withstand and recover from an SB0 of specified duration, requires licensees to submit infonnation as defined in 10 CFR Part 50.63 and requires licensees to provide a plan and schedule for confonnance to the SB0 rule. The 580 rule further requires that the baseline assumptions, analysis and related information be available for NRC review.
Guidance for conformance to the rule is provided by (1) Regulatory Guide (RG) i 1.155,StationBlackout,(2)NUMARC87-00,Guidelir.esandTechnicalBasesfor NUMARC Initiatives Addressing Station Blackout at Light Water Reactors, and (3) NUMARC 87-00 Supplemental Questions / Answers and Major Assumptions dated l
December 27,1989 (issued to the industry by NUMARC January 4,1990).
To facilitate the NRC staff's (hereafter referred to as staff) review of licensee responses to the 580 rule, the staff endorsed 2 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 generic response formats provide the staff with a sununary of the results from the licensee's analysis of the plant's 580 coping capability. The licensees are expected to verify the accuracy of the results and maintain documentation that supports the stated results. Compliance to the SB0 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 SB0 rule.
- Nuclear Management and Resources Council, Inc.
9608060125 960731
^
h1C P6-237, PDR
The licensee has submitted its response in the applicable generic response format.
The licensee's initial response was provided by letter from George C. Creel, Baltimore Gas And Electric, to the Document Control Desk, U. S. Nuclear Regula-tory Commission, dated April 14, 1989. Subsequently, the licensee provided a response to the NUMARC 87-00 Suppleraental Questions / Answers by a letter from George C. Creel to Document Control Desk, U. S. Nuclear Regulatory Comission, dated March 30, 1990. A third response pertaining to the AAC source was provided by letter dated June 6, 1990.
The licensee's responses and other information were reviewed by Science Applica-tions International (SAIC) under contract to the NRC. The results of the review are documented by SAIC Technical Evaluation Report (TER), SAIC-90/1072, titled
" Technical Evaluation Report, Calvert Cliffs Nuclear Power Plant, Unit Nos. I and 2, Station Blackout Evaluation," dated September 24,1990, (Attachment No.1).
Presently, there are three emergency diesel generators (EDGs) for the two units at Calvert Cliffs, one of which is shared between two units. The licensee plans j
to add two additional EDGs, thus providing two dedicated EDGs for each unit plus one spare EDG. The licensee intends to modify one of the three existing EDGs and use it as an AAC source, and additionally use this EDG (AAC source) as a sub-stitute for a dedicated EDG when one is out of service for an extended period due to maintenance and repair.
The licensee has stated that the AAC source would be available within one hour af ter the onset of an SB0 and would have the capacity and capability to power the equipment necessary to cope with an SB0 for the required 4-hour coping duration.
In addition, the licensee has indicated that he has performed a copying analysis for 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> to justify the use of the proposed AAC source EDG as a substitute for a dedicated EDG when one of them is out of service for an extended period, such as for a maintenance and repair.
2.0 EVALUATION
After reviewing the licensee's SB0 submittals and the SAIC TER, the staff concurs with the conclusions as identified in the SAIC TER (refer to Attachment No. I for
detailsofthereview).
Based on this review, the staff findings and recommenda-tions are summarized as follows.
2.1 Station Blackout Duration The licensee has calculated a minimum acceptable station blackout duration of 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> based on an offsite power design characteristic group of "P2", an Emer-gency AC configuration group "C", and an EDG reliability target of 0.975. The licensee also stated that the EDG target reliability was based on available EDG operability statistics for the last 100 demands.
The "P2" designation is based on the assumption that the frequency of grid-related LOOPS at the site is less than one in twenty years, or 0.05 per year.
However, we are aware of a recent incident on July 23, 1987, which was caused by a line to ground fault on one 500 kV transmission line and simultaneously a logic failure of the circuit breaker actuation circuitry on a second 500 kV line, resulting in a LOOP lasting nearly two hours.
i The above described event represents a grid-related LOOP frequency of greater than once in twenty years. Unless an analysis is provided that concludes that this event is not symptomatic of underlying or growing grid instability, this places the plant in an off-site AC power design characteristic group of "P3" l
in accoroance with R3 1.155, Table 4, or NUMARC 87-00, Section 3.2.1.
The j
licensee has not pravided such an analysis (er results of) in his SB0 submit-tals, therefore the staff concludes that AC power dasign characteristic is Group "P3".
The Group "P3" classification results in ari 3-hour required coping duration.
Recommendation: The licensee should reevaluate the plant's ability to cope with an SB0 based on an 8-hour coping duration and include these analyses with the other documentation supporting the SB0 submittal.
If the licensee desires recon-sideration of the coping category, sufficient justification with appropriate analysis should be provided for staff review which demonstrates the rationale for the July 23, 1987 LOOP not being considered as symptomatic of a grid-related LOOP.
t
.. _ _ ~. _ _ _...
~
2.2 Alternate AC (AAC) Power Source As discussed in Section 1.0, the licensee has proposed to add two new class IE EDGs. The addition of two EDGs would make Calvert Cliffs Nuclear Power Plant r
(CCNPP) as having a total of five EDGs with two EDGs dedicated to each unit.
The licensee proposes to modify and designate one of the three existing EDGs as a spare which would be used as an AAC power source for coping with an SBO. Also the licensee intends to use this EDG as a substitute for any of the normal dedi-cated EDGs when the dedicated EDG is unavailable due to maintenance and repair.
However, the licensee has not provided any details of the EDG configurations and connections, or which existing EDG will be modified and designated as an AAC power source.
2.2.1 General staff position on AAC power sources f
The definition in 10 CFR 550.2, RG 1.155 and NUMARC 87-00 define an AAC power source in terms of four attributes: (1) connections to the offsite or the on-site AC power systems, (2) minimum potential for connon cause failure with off-site power or the onsite emergency AC power sources, (3) timely availability, and (4) required capacity and reliability. More specifically, in regard to the fourth attribute, the 5B0 rule reads as follows:
"(4) Has. sufficient capacity and reliability for i
operation of all systems required for coping with station blackout and for the time required to bring and maintain the plant in safe shutdown (non-design basis accident)."
l In view of the variety of. types, capacities and capabilities of power sources proposea as AAC sources by various licensees, the staff has characterized pro-posea-AAC power sources as being either optimum, fully capable or partially capable. Tnis characterization, which relates only to the capacity attribute cited above, was necessary in order to facilitote the staff review of licensee responses to the SB0 rule.
It does not invalidate or revoke any of the require-ments or guidance applicable to AAC power sources.
i f'
! l
l 5
i An optimum AAC power source design is one that is capable of powering simultan-eously both safety trains of nurmal safs shutdown systems and equipment. Such a design, following actuation of the AAC source, would provide completely re-dundant normal safe shutdown capability curing an 580 and recovery therefrom from the main control room.
A fully capable AAC power source design is one that is capable of powering at least one complete safety train of normal safe shutdown systems and equipment.
This includes decay heat removal, battery charging, HVAC (heating, ventilation and air conditioning), emergency lighting, and the associated controls and instrumentation. Thus, although redundant capability is not available, a fully capable AAC source would enable attainment of safe shutdown during an 580 and recovery therefrom from the main control room.
A minimally capable AAC power source design is one that is not capable of power-ing all (or any) normal safety train related safe shutdown equipment; but it is l
capable of powering specific equipment that, in conjunction with extensive manual operator actions both inside and outside of the control room, is critical for I
attaining safe shutdown during an SBO. Appendix R diesels proposed as an AAC source are examples of minimally capable AAC sources. With this design, oper-I ability of the main control room could not be assured unless the batteries were j
sized to operate for the SB0 duratiun, or battery charging capability was pro-I viced by the AAC source.
2.2.1.1 Connectability of AAC power sources The basic criteria governing the connectability of an AAC power source are con-tained in 10 CFR 50.2 (The AAC source should be connectable to but normally not connected to the offsite or onsite emergency AC power systems), 10 CFR 50.63 (SB0 should not assume a concurrent single failure or design basis accident).
l Therefore, in a two unit site as a minimum an AAC source need only be connect-able to one set of safe shutdown equipment for each unit, regardless of whether that equipment is part of a safety train or not, or whether the AAC source is an excess redundancy EDG or an independent power source.
-C-2.2.2 Proposed AAC power source The CCNPP is a two-unit site. The present emergency AC power configuration has one EDG dedicated to each unit with a third EDG (shared) that is connectable to one safety bus in either unit. As stated in Section 1.0, the licensee has proposed the installation of two additional EDGs, and modifications to one of the three existing EDGs for use as an AAC power source. The two new additional EDGs will be installed as safety-related oedicated EDGs, one for each unit.
l The proposed AAC source would be connectible to at least one of the safety buses (possibly to all buses) in either unit and would be available to power the SB0 loads within one hour following an 580 event. The proposed AAC source would be j
started from the control room but will require actions outside the control room to connect it to a safety bus. The licensee has not specifically committed to perform a test to demonstrate that the AAC source can power the SB0 loads within one hour in accordance with the guidance of Appendix B to NUMARC 87-00.
l The licensee has not, however, provided sufficient detail on the proposed over-l all design modifications. Additionally, the licensee has indicated that the AAC source could be substituted for one of the dedicated Class IE EDGs for an extended period when the normal dedicated EDG is out of service for repair and maintenance.
These changes affect the safety related electrical system design and may also result in technical specification changes. Changes which affect the original plant safety system design as described in the FSAR and the required changes in l
the technical specifications should be submitted as a separate item from SB0 and reviewed by the staff against the apprcgriate criteria. Although the licensee did not indicate that the proposed AAC source meets the NUMARC 87-00, Appendix B criteria, the staff expects that since the proposed AAC source is Class 1E, it will meet the criteria in Appendix B to NUMARC 87-00.
The licensee had originally proposed both AAC and 4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> coping approaches to the SB0 issue. However, the staff has found the plant to have a required 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> duration; thus, the proposed duration and related coping analysis would be inade-quate for 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> duration. Subject to provision of information from the licensee which alters the staff conclusion, the plant design for SB0 is being accepted on the basis of AAC alone. Thwefore, the use of the AAC source as a substitute for i
i
~
one of the existing EDGs is an acceptable practice provided the electrical design is found acceptable and an acceptable time limit is placed on its use in this manner. However, the licensee needs to submit all of the information (i.e.,
design modifications details) necessary for the staff evaluation of the pro-1 t
posed modifications with respect to the appropriate criteria and regulations.
i With the installation of two additional EDGs at CCNPP (a total of five ED65),
the CCNPP will have a spare EDG available on site that is in addition to the t
EDGs required to meet the minimuct EDG redundancy requirement for powering a normal safe shutdown for a LOOP event. Therefore, the CCNPP meets the guidance on the use of existing EDGs at multi-unit sites for cualifying EDGs as AAC sources based on exceeding minimum redundancy. Based on the above, the CCNPP meets the " fully capable" classification discussed above in Section 2.2.1 and l
satisfies the connectability requirements of Section 2.2.1.1.
Recommendations:
1.
The licensee should submit separately for staff review the overall design information on the proposed EDG modifications and installation of additional EDGs. This information should include the modifications to the EDG's buses, cables and associated systems. The licensee should also include information ontheEDG(spare)whenusedasanAACsourceandwhensubstitutedfora dedicated EDG when it is out for maintenance and repair. LCO and TS changes on the dedicated EDGs and the proposed AAC source should also be provided.
In addition this information should also be included in the documentation supporting the SB0 submittal maintained by the licensee.
2.
The licensee should demonstrate that the AAC power source is available for supplying the SB0 loads within one hour of the onset of an SB0 event by i
conducting the appropriate testing in accordance with the guidance of NUMARC 87-00, Appendix B, Item B.12.
)
I i
- 2.3 Station Blackout Coping Capability t
The licensee has performed a four hour coping analysis independent of the AAC source to support those periods of time when the spare diesel is substituted for one of the dedicated EDGs and is not available as an AAC source. The licensee j
also plans to have separate procedures for the situations when the spare diesel I
is or is not available as an AAC source.
i Based on the evaluation in Section 2.1, the staff has determined that the re-quired coping duration is 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> to cope with an 8-hour 5B0, the staff assumes that one of the three existing EDGs after modifications qualifies as an AAC source and meets the criteria of NUMARC 87-00, Appendix B.
The following anal-ysis, therefore, assumes that the AAC source will be available within one hour to power the loads necessary to cope and recover from an 8-hour S80.
I' The characteristics of the following plant systems and components were reviewed to assure that the systems have the availability, adequacy and capability to i
achieve and maintain a safe shutdown and recover from the SB0 for the required 8-hour coping duration.
2.3.1 Condensate inventory for decay heat reseval The licensee calculated that 98,000 gallons of water are required for each unit during an 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> SB0 duration. The condensate storage tank (CST) inventory of 300,000 gallons of water for both units (the minimum technical specification (TS) requirement) is adequate to maintain steam generator decay heat removal capa-bility for an 8-hour coping duration. The licensee's calculation apparently did not consider any inventory loss due to RCS cooldown in the NB0 unit. Although, we do not disagree that there is probably sufficient inventory for removing decay heat from both units and RCS cooldown in the NB0 unit, we conclude that the licensee should have an analysis to desenstrate this adequacy.
Recommendation: The licensee should confirm that there is sufficient inventory to remove the decay heat from both units and also provide for cooldown in the
,i I
i ;
NB0 unit and include this confirmatio. in the documentation supporting the SB0 submittal maintained by the licensee.
2.3.2 Class IE battery capacity The licensee has stated that a battery calculation has been performed pursuant to NUMARC 87-00 to verify.that the Class 1E batteries have sufficient capacity to cope with an SB0 for four hours. Since the proposed AAC power source will be available within one hour to power the battery chargers, the batteries are assumed i
to have sufficient capacity to support SB0 loads for an 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> coping duration.
2.3.3 Compressed air The licensee stated that the air-operated valves relied upon to cope with an 580 can be operated manually. Although, we do not disagree with this, our analysis indicates that a successful decay heat removal curing the first hour may require close coordination of at least two operators. Therefore, the licensee needs to simulate this scenario to demonstrate that it can be satisfactorily accomplished in accordance with the procedures that are to be established.
Recommendation: The licensee should establish procedures and simulate appropri-ate actions and provide operator training to assure that decay heat removal can be adequately maintained during the first hour of an SB0 event.
2.3.4 Effects of loss of ventilation The licensee stated initially that their calculations showed that the steady-state temperature of the AFW Pump Room would reach 130'F and the control room would be less than 120*F during a four hour 580.
No other areas were identi-fied as dominant areas of concern. Subsequently, the licensee stated that it will be necessary to permanently open up portions of the drop ceiling in the control room and the doors to the AFW rooms'during an 580 to limit temperature rises. The revised temperatures for these rooms were not provided, nor were the steady-state, temperatures provided for seven other areas that were calculated.
Also, no mention was made of opening the control room cabinet doors within 30 minutes in accordance with NUMARC guidance.
Further, as noted in the attached
~
i 1
l l
TER, the licensee's heat-up calculations are based on methods other than those proposed in NUMARC 87-00. The information provided is not sufficient to assure the NRC staff that the methodology used has been verified as to its decuracy, or that it has been found acceptable for the purpose for which it has been used.
Also, more information is needed regarcing the assumptions and initial conditions used in the calculations.
In particular, the assumptions used for walls greater than 8-inches thick, and concrete block walls that are filled, were not provided.
Recorrinenaation: The licensee should reanalyze the heat-up analyses of the areas ofconcern(seeAttachment1)basedonan1-hourduration,includinginformation to demonstrate the acceptability of the methodology, assumptions and initial condi-tions used in the calculacions. This assumes HVAC for cominant areas of concerns will be powered by the proposed AAC power source after 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />. Also, the licensee j
should document additional justification as to why it is not necessary to open cabinet doors in the control room within one half hour after the onset of an SB0 event. The licensee should include the above analyses and results in the docu-i i
mentation supporting the SB0 submittal maintained by the licensee.
2.3.5 Containment isolation The licensee has reviewed the plant list of containment isolation valves needed for containment isolation and has verified that containment integrity can be established during an SBO. After reviewing the available documentation and the SAIC TER, the staff finds that the licensee's analysis is in accordance with RG 1.155, Section 3.2.7.
The staff therefore concludes that there is reasonable assurance that containment integrity can be obtained during an SBO.
2.3.6 Reactor coolant inventory l
The licensee stated that a plant specific analysis shows that the expected rates l
of reactor coolant inventory loss do not result in core uncovery during a four l
hour SB0 event, and therefore no make-up systems are required to maintain core cooling under natural circulation including the effect of reflux boiling. The staff concludes, based on analyses of similar plants, that the core would remain covered for the 8-hour coping duration, with an expected loss of 112 gpa provided
that two charging pumps are kept operating once the AAC source is established.
However, the licensee should have an analysis which conforms to the above assumed laakage rate and shows adequate core coverage during an 8-hour SB0 event.
5 Recomendation: The licensee should perform the necessary analyses to show that a reactor coolant inventory loss of 112 gpm does not result in core uncovery j
during an eight hour SB0 event. The licensee should include these analyses and results in the documentation supporting the SB0 submittal maintained by the I
licensee.
i 2.4 Procedures and Training
)
The licensee has stated that plant procedures exist which meet NUMARC 87-00 guide-1 i
lines for AC power restoration and severe weather conditions. In addition, the licensee has reviewed plant procedures, and has comitted to modifying these procedures in accordance with NUMARC 87-00 guidelines, for a response to an SB0,
)
including those associated with the SB0 modifications. Although the licensee did i
not specifically mention training requirements pertaining to these procedures, the staff expects that such training will be provided.
The proposed procedural modifications were not reviewed, but the staff expects j
the licensee to maintain these procedures to ensure an appropriate response to I
an SB0 event. With this understanding, the staff finds the licensee's comitment l
to implement procedures in accordance with NUMARC guidelines to be acceptable.
2.5 Proposed Modifications i
As discussed previously, the licensee plans to install two additional Class 1E EDGs including associated switchgear and support systems, resulting in two dedi-cated EDGs for each nuclear unit. One of the three existing EDGs will be modified to be used as an AAC source.
In addition, the licensee proposes to open up 30% of the control room drop ceiling, proposes to modify the battery room HVAC systems to ensure that the battery room temperatures will not fall below a specified minimum temperature, and provide battery power to the power operated relief valves (PORVs),
12 the PORY block valves, various control room indicator lights, and one channel of the reactor vessel level monitoring system (RVLMS). The staff finds that the pro-posed modifications including the addition of two Class IE EDGs as part of the normal cedicated EDG reconfiguration and the modifications of one of the three existing EDGs as part of the AAC source implementation will meet the applicable guidelines.
Recomendation: The licensee should provide a full description including the nature and objectives of the required modifications identified above in the documentation supporting the SB0 submittal that is to be maintained by the ifcensee.
It should be noted that the modifications relating to the reconfigu-ration of the existing EDGs and the addition of two others have not been reviewed under the SB0 review and should be submitted separately for staff review as indi-cated in the recomendations in Section 2.2.2.
2.6 Quality Assurance and Technical Specifications The licensee did not address in their submittals the issues of a quality assur-ance program or Technical Specifications for the SB0 equipment in accordance with the guidance of RG 1.155, C.3.5.
The technical specifications for the SB0 equipment are currently being con-sidered generically by the NRC in the context of the Technical Specification l
I Improvement Program and remains an open item at this time. However, the staff would expect that the plant procedures will reflect the appropriate testing and surveillance requirements to ensure the operability of the necessary SB0 equipment.
If the staff later determines that TS regarding the 580 equipment is warranted, the licensee will be notified of the implementation requirements.
Recommendation: The licensee should implement a quality assurance program that meets, as a minimum, the guidance of RG 1.155, Appendix A, for any equipment not presently covered by an equivalent QA program.
i 2.7 EDG Reliability Program i
l The licensee's March 30, 1990 submittel comitted to maintain the EDG targeted reliability of 0.975 iii accordence with NUMARC guidance and the proposed re-vision to RG 1.9.
We consider this as a comitment that the licensee will implement an EDG reliability program which meets the guidance of RG 1.155, Section 1.2 i
i Reconnendation:
The licensee should verify that a program that meets the guidance of RG 1.155, Section 1.2 is_in place and include this verification in the documentation supporting the S80 submittal that is to be maintainea by the licensee.
2.8 Scope of Staff Revie_w The station blackout rule (10 CFR 50.63) requires-licensees to submit a response i
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". Thestaffanditscontractor(SAIC)did not perform a detailed review of the proposed hardware and procedural modifica-tions which are scheduled for later implementation. However, based on our review of the licensee's submittals 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 SB0 rule.
a.
Hardure and procedural modifications, b.
SB0 procedures in accordance with RG 1.155, Position 3.4, and NUMARC 87-00, Section 4, l
c.
Operator staffing and training to follow the identified actions in the 580 procedures, 1
d.
EDG reliability program meets, as a minimum, the guidelines of RG 1.155, l
e.
Equipment and components reouired to cope with an SB0 are incorporated in a QA program that meets the guidance
~
of RG 1.155, Appendix A, and f.
Actions taken pertaining to the specific recommendations noted in this SER.
3.0
SUMMARY
AND CONCLUSIONS:
The staff has reviewed the licensee's response to the SB0 rule (10 CFR 50.63) and the Technical Evaluation Report prepared by the staff's consultant, Science Applications International Corporation. We find that several reevaluations and confirmations still need to be completed as described in the recommendations itemized herein. These include reevaluating the plant's ability to cope with an SB0 for 8-hours, confirmation that the modified EDG to be used as an AAC source meets the criteria of Appendix B to NUMARC 87-00, reevaluating the effects of loss of ventilation in areas of' concern (see Attachment 1), reeval-uating the adequacy of reactor coolant system inventory for the 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> duration, confirmation that a quality assurance program for the SB0 equipment will be implemented in accordance with the guidance of RG 1.155, C.3.5, and confirmation that an EDG reliability program in accordance with RG.1.155, Section 1.2 will be implemented. The licensee should maintain all analyses, confirmations and other documentation supporting the SB0 submittal available for further inspection and assessment as may be undertaken by the NRC to further verify conformance with the SB0 rule. Based on our review of the submittal, we find the licensee's pro-posed design and method of dealing with an SB0 to be in conformance with the SB0 rule contingent upon receipt of confirmation from the licensee within 30 days that the recommendations identified in this SER will be implemented. The schedule for this implementation should also be provided to the NRC within 30 days of receipt of this SER in accordance with 10 CFR 50.63 (c)(4).
+
SALP INPUT t
e FACILITY NAME:
Calvert Cliffs
SUMMARY
OF REVIEW:
The licensee responded to the Station Blackout Rule (10 CFR 50.63) by letters dated April 14, 1989; March 30, 1990 and June 6, 1990. The NRC staff found that the licensee conforms to the SSO rule in most areas, but some concerns remain to be resolved.
NARRATIVE DISCUSSION OF LICENSEE PERFORMANCE FUNCTIONAL AREA: ENGINEERING / TECHNICAL SUPPORT:
The licensee's initial response adequately addressed the issues and generally conformed to the guidance provided for addressing the Station Blackout Rule.
Subsequent submittals provided additional information. Although several items still need to be resolved, these were not unexpected and are similar to those experienced by the staff during other reviews. The licensee presented the information in a clear and concise manner and displayed a good technical under-standing of the safety issues involved, inoicating a high degree of technical competence, adequate training and management control.
Author:
A. Toalston Date:
August 28, 1990 9
l
mr SAIC-90/1072 j
1 i
l TECHNICAL EVALUATION REPORT CALVERT CLIFFS NUCLEAR POWER PLANT UNIT Nos. 1 AND 2 STATION BLACK 0UT EVALUATION TAC Nos. 68525 and 68526 1
1 l
SAIC Science ApplicationsInternationalCorporation An Employee-Owned Company Final September 24, 1990 Prepared for:
U.S. Nuclear Regulatory Commission Washington, D.C. 20555 Contract NRC-03-87-029 Task Order No. 38 e,.,,,.,,.. A,,o92y
- 376, up 7
-v'-
M Post Once Box 1303.1710 Getxtndge Dove. McLean. Virginia 22102 (703) 8214300
1 l
l TABLE OF CONTENTS l
l Section fagg l
1.0 BACKGROUND
1 l
l 2.0 REVIEW PROCESS.......................................
3 3.0 EVALUATION...........................................
6 1
3.1 Proposed Station Blackout Duration..............
6 I
3.2 Alternate AC (AAC) Power Source...................
10 3.3 Station Blackout Coping Capability..............
11
)
i 3.4 Proposed Procedures and Training................
18 3.5 Proposed Nodifications..........................
19 3.6 Quality Assurance and Technical Specifications..
21 l
1
4.0 CONCLUSION
S...........................................
22
5.0 REFERENCES
24 1
l l
l 6
11 l
l
l TECHNICAL EVALUATION REPORT CALVERT CLIFFS NUCLEAR POWER PLANT UNIT Nos. i AND 2 STATION BLACK 0Ut EVALUATION
1.0 BACKGROUND
On July 21, 1988, the Nuclear Regulatory Commission (NRC) amended its regulations in 10 CFR Part 50 by adding a new section, 50.63, " Loss of All Alternating Current Power" (1).
The objective of this requirement is to assure that all nuclear power plants are capable of withstanding a station blackout (SBO) and maintaining adequate reactor core cooling and appropriate containment integrity for a require duration. This requirement is based on information developed under the commission study of Unresolved Safety Issue A-44, " Station Blackout" (2-6).
The staff issued Regulatory Guide (RG) 1.155, " Station Blackout," to provide guidance for meeting the requirements of 10 CFR 50.63 (7).
Concurrent with the development of this regulatory guide, the Nuclear Utility Management and Resource Council (NUMARC) developed a document entitled, " Guidelines and Technical Basis for NUMARC Initiatives Addressing Station Blackout at Light Water Reactors," NUMARC 87-00 (8).
This document provides detailed guidelines and procedures on how to assess each plant's capabilities to comply with the SB0 rule.
The NRC staff reviewed the guidelines and analysis methodology in NUMARC 87-00 and concluded that the NUMARC document provides an acceptable guidance for addressing the 10 CFR 50.63 requirements. The application of l
this method results in selecting a minimum acceptable SB0 duration capability from two to sixteen hours depending on the plant's characteristics and vulnerabilities to the risk from station blackout. The plant's characteristics affecting the required coping capability are:
the redundancy of the onsite emergency AC power sources, the reliability of onsite emergency power sources, the frequency of loss of offsite power (LOOP), and the probable I
time to restore offsite power.
1 1
In order to achieve a consistent systematic response from licensecs to the SB0 rule and to expedite the staff review process, NUMARC developed two generic response documents.
These documents were reviewed and endorsed by the NRC staff (11) for the purposes of plant specific submittals.
The documents are titled:
1.
" Generic Response to Station Blackout Rule for Plants Using Alternate AC Power," and i
l 2.
" Generic Response to Station Blackout Rule for Plants Using AC Independent Station Blackout Response Power."
i A plant-specific submittal, using one of the above generic formats, provides only a summary of results of the analysis of the plant's station blackout coping capability.
Licensees are expected to ensure that the baseline assumptions used in NUMARC 87-00 are applicable to their plants and to verify the accuracy of the stated results. Compliance with the SB0 rule requirements is verified by review and evaluation of the licensee's submittal and audit review of the supporting documents as necessary.
Follow up NRC inspections assure that the licensee has implemented the necessary changes as required to meet the SB0 rule.
In 1989, a joint NRC/SAIC team headed by an NRC staff member performed audit reviews of the methodology and documentation that support the licensees' submittals for several plants. These audits revealed several deficiencies which were not apparent from the review of the licensees' submittals using the agreed upon generic response format. These deficiencies raised a generic question regarding the degree of the licensees' conformance to the requirements of the SB0 rule. To resolve this question, on January 4, 1990, NUMARC issued additional guidance as NUMARC 87-00 Supplemental Questions / Answers (12) addressing the NRC's concerns regarding the deficiencies.
NUMARC requested that the licensees send their supplemental I
responses to the NRC addressing these concerns by March 30, 1990.
l l
2 l
l i
l 7'
2.0 REVIEW PROCESS The review of the licensee's submittal is focused on the following areas consistent with the positions of RG 1.155:
l 1
A.
Minimum acceptable S80 duration (Section 3,1),
B.
S80 coping capability (Section 3.2),
t L
C.
Procedures and training for S80 (Section 3.4),
i i
l D.
Proposed modifications (Section 3.3), and l
E.
Quality assurance and technical specifications for 580 equipment l
(Section 3.5).
For the determination of the proposed minimum acceptable SB0 duration, l
the following factors in the licensee's submittal are reviewed:
a) offsite i.
j power design characteristics, b) amergency AC power system configuration, c) determination of the.mergency diesel generator (EDG) reliability consistent with NSAC-108 criteria (9), and d) determination of the accepted EDG target l
reliability. Once these factors are known, Table 3-8 of NUMARC 87-00 or Table l
2 of RG 1.155 provides a matrix for determining the required coping duration.
For the SB0 coping capability, the licensee's submittal is reviewed to assess the availability, adequacy and capability of the plant systems and components needed to achieve and maintain a safe shutdown condition and recover from an 500 of acceptable duration which is determined above. The review process follows the guidelines given in RG 1.155, Section 3.2, to assure:
a.
availability of sufficient condensate inventory for decay heat j
- removal, l
i 3
l
.,,y
'I b.
adequacy of the class IE battery capacity to support safe
- shutdown, c.
availability of adequate compressed air for air-operated valves necessary for safe shutdown, d.
adequacy of the ventilation systems in the vital and/or dominant areas that include equipment necessary for safe shutdown of the
- plant, e.
ability to provide appropriate containment integrity, and f.
ability of the plant to maintain adequate reactor coolant system inventory to ensure core cooling for the required coping duration.
The licensee's submittal is reviewed to verify that required procedures t
(i.e., revised existing and new) for coping with S80 are identified and that appropriate operator training will be provided.
The licensee's submittal for any proposed modifications to emergency AC sources, battery capacity, condensate capacity, compressed air capacity, appropriate containment integrity and primary coolant make-up capability is t
reviewed. Technical specifications and quality assurance set forth by the licensee to ensure high reliability of the equipment, specifically added or assigned to meet the requirements of the SB0 rule, are assessed for their adequacy.
i The licensee's proposed use of an alternate AC power source is reviewed to determine whether it meets the criteria and guidelines of Section 3.3.5 of RG 1.155 and Appendix B of NUMARC 87-00.
This SB0 evaluation is based on the review of the licensee's submittals dated April 14, 1989 (10), March 30, 1990 (13), and June 6, 1990 (14), and the information available in the plant Updated Final Safety Analysis Report (UFSAR) (15); it does not include a concurrent site audit review of the 4
supporting documentation.' Such an audit may be warranted as an additional confirmatory action. This determination would be made and the audit would be scheduled and performed by the NRC staff at some later date.
5
~
d.
Estimated frequency of LOOPS due to severe weather (SW) which places the plant in SW group "2."
2.
Emergency AC (EAC) Power Configuration Group The EAC power configuration of the plant is "C."
Each unit at CCNPP.will be equipped with two emergency diesel generators. One EAC power supply per unit is necessary to operate safe shutdown equipment following a LOOP.
3.
Target Emergency Diesel Generater (EDG) Reliability The licensee has selected a target EDG reliability of 0.975. The selection of this target reliability is based on having an average EDG reliability of greater than 0.95 for the last 100 demands consistent with NUMARC 87-00, Section 3.2.4.
Review of Licensee's submittal Factors which affect the estimation of the SB0 coping duration are: the independence of the offsite power system grouping, the estimated frequency of LOOPS due to ESW and SW conditions, the expected frequency of grid-related LOOPS, the classification of EAC, and the selection of EDG target reliability.
The licensee's estimation of the frequency of LOOPS due to ESW conditions is consistent with that given in Tables 3-2 of NUMARC 87-00. The licensee used site specific data to estimate the expected frequency of LOOPS due to SW conditions at CCNPP (13). Use of the site specific data places the site in SW group "2."
Use of the data given in NUMARC 87-00 places the site in SW group "1."
The licensee's estimate results in a more severe weather condition and, therefore, it is more conservative than that which results from the NUMARC 87-00 data.
Hence, we agree with the licensee's stated ESW and SW groupings for the CCNPP site.
7
I l
The licensee stated that the independence of the plant offsite power system grouping is "II/2." A review of CCNPP UFSAR indicates that, (see Figure 1):
1.
All offsite power sources are connected to the plant through one l
l 2.
The plant emergency buses are powered from offsite power sources through two 13.8 kV service buses (Bus 11 and 21).
I 3.
Each 13.8 kV service bus is powered from one offsite power source.
4.
There are two 4.16 kV emergency buses in each unit.
Each is powered from one service bus.
5.
Upon loss of power from one service bus, all emergency buses will be connected to the other service bus.
Using the guidance provided in Table 5 of RG 1.155 the independence of offsite power characteristics can be categorized as "I2."
We agree with the licensee that the EAC classification of CCNPP after
.mplementation of the proposed modifications (addition of two EDGs) will be "C."
We are unable to verify the assignment of the EDG target reliability at this time. However, based on the information in NSAC-108, which gives the EDG reliability data at U. S. nuclear reactors for calendar years 1983 to 1985, the EDGs at CCNPP axperienced an average of 146 valid start demands per calendar year with an average unit reliability of 0.992 per diesel per year. Using this data, it appears that the target EX rdiability (0.975) selected by the licensee (10) to be appropriate. However, the licensee needs to have the EDG reliability data for the last 20, 50, and 100 demands on file as part of the SB0 submittal supporting documents. The licensee stated that (13) the selected target reliability will be maintained, and that a.1 EDG reliability program consistent with the NUMARC guidance and the revised 8
l
!i.si 1 ti y y malm a a sua a m i
g! f d'
)
tl. 1 I
7:el; l
d la j
j I.
l I
h! 'i. n. > > lhli.m in dilll l
d'i j!!!ijlljj
.I 0!
1:!
k, N hi i
j f j g --
g 2
e
% " >x,:
.* A p,ra
- 1 -
@u
^
"d A^ ^
r;
^ 's
- - s '
.x8 h*s.
I m'i e n_,.
kq'i
~ ;'t l
(
5 g
I Va~~'
't -m
- 2) ph;r%q >t2 l
8 5
>,, 2 2 I
r
-^
5 2
IL 5,H^ ^
1 se-i i
<r ll m
e,5 i
i d
o T
m'a st 2n T
r
=
w N
h
.U.
5
[M 2T2 I
^
h
^
i l3r prif23 D fyl_^
s 4
! I' N
K;lver 3
2<
c P
s r
i s
-y--
Ta_ 4
'scr!
- s c
-5r{l.
y W,.
2- ;z I
y2 W,
s tl_Jrev;2 hi gvj is -2lq'
'g g g' l
7 a
est 2 die""
^
8 rt d
l; e
l i
i.
b
~
~-
_I m..
gl
-g$g g-(3 s
lp.
jv!
g 5-S'jvl lTEf[^i*'
~
4.^ ^
i y
_35.
h g-N Y
Y 8
,pl__
)e [bn l
-g i s l_^
' "- ls*.
Ul p
e*
Y 3
.c e-- i r-$
rv N
UtA e
Y g"%
W n
a "l
'I 1 6-
$7 i'.*.
^
l ^ t o. n if -
eJt n "[
I 5 s s' m,
I b.
c h;r'h !
A A
.I 2 CiE-* ~f W =EP.g g,
'r e
i s
,t
^
a.m iu aS c'l adY
'h L
)E!
Y a
g.-
y "2
W,. v
^
i _m g
tv) s ya sa a :5 D
Tl
+"y T!
8
+gk >~2"a-s 4,
d.'.-_
l'.
2 i
lT n-ia WJ
.i 3
2 w a,
- i Ir RQL 2tp
^
t 9
RG 1.9 will be used to ensure that the selected target is met.
We I
consider this as a commitment inat the licensee will establish a reliability program consistent with the guidance of RG 1.155.
With regard to the expected frequency of grid-related LOOPS at the site, the licensee stated that the frequency of grid-related loops at the site is less than one in 20 years, or.0.05 per year. However, we are aware of a recent incident on July 23, 1987 (16), in which a line to ground fault on one of the 500 kV transmission line coincident with failure of a circuit breaker logic actuation circuitry resulted in loss of both 500 kV offsite power lines to the site.
This event, which caused both units to trip and lasted nearly two hours, should have been considered as a grid-related event. Since CCNPP has less than 20 years of operating experience, the occurrence of one grid-related LOOP event places the site in an offsite power design characteristic group "P3."
The licensee can provide justifications to the NRC staff on why the event of July 23, 1990 should not be considered as a grid-related LOOP event, or revise its coping calculations for eight hours.
Based on above evaluations, the plant is categorized as "P3" with a minimum required SB0 coping duration of eight hours.
3.2 Alternate AC (AAC) Power Source Licensee's Submittal Although the licensee did not clearly state that the CCNPP is an AAC site, the revised submittals (13 and 14) indicate that after the addition of two class IE diesel generators the site will have a spare diesel. The spare diesel, one of the existing EDGs, will be modified to be used as an AAC power source. The licensee stated that the AAC power
~
source will meet all of the criteria specified in Appendix B to NUMARC 87-00. Although the spare diesel can be started from the control room, actions must be taken outside the control room to connect it to a 10 i
l
i j
i I
safety-related bus.' With this configuration, the AAC power source is l
available within one hour.
l i
l The licensee also intends to use the spart diesel as a dedicated EDG for a unit when one of that unit EDGs is out of service for repair or f
maintenance. With this configuration, the licensee claims that analyses j
l_
have been performed to support an AC-independent coping of four hours for both units (10 and 14).
l Review of Licensee's Submittal The AAC power source, one of the existing EDGs, meets stricter criteria, 7
(i.e. criteria applicable to the class IE power supply), than those j
required per Appendix B to NUMARC 87-00.
The AAC power source (possibly
{
i I
the existing shared diesel) has sufficient capacity to fully power the required safe shutdown loads following a LOOP.
The licensee needs only to demonstrate by a test that the AAC power source can be established I
and connected to the required safe shutdown equipment within one hour from the onset of an SB0 event.
The option of using the spare diesel as a dedicated EDG was not
(
reviewed, since the licensee has not shown that the site can cope for l
eight hours independent of AC power. The licensee's intention for using this option is presumably to get a technical specification limiting condition for operation (LCO) exemption when an EDG is out of service.
If the licensee wishes to use this option, it should submit its request to the NRC staff under technical specification improvement program.
l 3.3 Station Blackout Coping Capability i
f
(
The licensee's coping analysis is reviewed based on the assumption that l
the spare diesel will be used as an AAC power source which will be available l
within one hour from the onset of an S80 event. The use of the spare diesel j
as an EDG instead of an AAC needs to be evaluated as part of the technical 2
specification improvement program.
Should the licensee wish to use the spare 1
11
l diesel as an EDG instead of an AAC power source, it needs to provide 8-hour coping calculations for the NRC's review.
The following summarizes our review of the plant coping capability with an SB0 event for the required duration of eight hours:
1.
Condensate Inventory for Decay Heat Removal Licensee's Submittal The licensee's submittal (10) stated that 98,000 gallons of water are required per unit to remove decay heat during an 8-hour SB0 event.
The minimum permissible condensate storage tank (CST) level per technical specification provides 300,000 gallons of water for both units, which exceeds the required quantity for coping with an SB0 of eight hours duration.
The licensee added i
that no plant modifications or procedure changes are needed to utilize this water source.
Review of Licensee's Submittal Using the expression provided in NUMARC 87-00, we have estimated that each unit would need -98,000 gallons of condensate water to remove decay heat from the reactor core during an 8-hour SB0 event.
This estimate is based on a reactor thermal power of 2,754 MWt, or 102% of the rated power. The CCNPP has only one CST which contains a minimum of 300,000 gallons of condensate for use at both units.
It is prudent to assume that during the eight hour coping requirement the non-blacked out (NBO) unit will be cooled down to a rector coolant system (RCS) pressure at which the residual heat removal (RHR) pump can be used to remove decay heat.
Therefore, the total amount of the condensate water required for both units will be the sum of the condensate needed to remove decay heat in the blacked-out unit and to remove decay heat and RCS cooldown in the NB0 unit. Our experience with similar plants 12 l
)
i indicates tha't this sum would not exceed the CCNPP minimum i
available CST volume. Therefore, we agree with the licensee that the site has sufficient condensate inventory to cope with an 8-hour SB0 event.
2.
Class IE Battery capacity Licensee's submittal The licensee stated that a battery capacity calculation has been performed to verify that the class IE batteries have sufficient capacity to meet the SB0 loads for four hours.
Review of Licensee's Sutsittal A review of the plant UFSAR (Section 8.4.2) indicates that each unit has two battery banks.
Each battery bank is capable of carrying the connected loads for two hours without charge.
Since the AAC power source will be available within one hour and supply the battery charger (s), we conclude that the plant has sufficient battery capacity.
3.
Compressed Air Licensee's Submittal The licensee stated that the air-operated valves relied upon to cope with an SB0 for four hours can be operated manually. Valves requiring manual operation are identified in plant procedures.
Review of Licensee's Submittal Our review of the plant UFSAR indicates that both the auxiliary feedwater (AFW) flow control valves and the steam generator pilot operated relief valves (PORVs) are air-operated valves which would 13
require local
- manual actions for their operation during an SB0 event. The licensee stated that the PORVs will be modified to be l
DC powered relief valves, (see Section 3.5).
During the first hour these valves need to be modulated manually to control the reactor cooldown and remove decay heat from the reactor core. A successful decay heat removal operation, therefore, requires close coordination of at least two operators: one in the control room to monitor the steam generator level and control the steam release through the PORVs, and the second one at the AFW flow control valves to manually adjust the AFW flow. Hence, the licensee needs to simulate this operational scenario and train the operators accordingly.
A review of the plant UFSAR also indicates that each unit has two instrument air compressors which are supported by the unit EDGs.
Therefore, after one hour, when the AAC power source is established, the instrument air would be available to power the l
air operated valves needed to cope with an 8-hour SB0 event.
i 4.
Effects of Loss of Ventilation Licensee's submittal The licensee stated (13) that detailed room heat-up calculations were performed for nine different areas of the plant.
In four of these areas: main steam isolation penetration rooms, east piping penetration rooms, elevation 27' switchgear rooms, and elevation 45' switchgear rooms, NUMARC methodology was generally followed.
In the cable spreading rooms and containments, alternative methods were used to calculate room temperatures. This was necessary to model time dependent heat sources and, in the case of containment, I
i to model the steel liner.
For the remaining three areas: control I
l room, data acquisition rooms, and auxiliary feedwater rooms, a i
modified NUMARC method was used.
l l
The licensee'provided the following finai post SB0 steady-state ambient air temperatures in its submittal dated April 14, 1989 (10):
a.
AFW Pump Room 130*F b.
Control Room Complex
< 120*F The licensee stated that reasonable assurance of the operability of SB0 response equipment in the above dominant areas of concern has been assessed using the Appendix F to NUMARC 87-00 and/or the equipment operability Topical Report.
The licensee concluded that L
no modifications or associated procedures changes are required to provide reasonable assurance for equipment operability.
In the revised submittal (13), however, the licensee stated that, in order to make a large enough heat sink available in the main control room, portions of the drop ceiling will be permanently l
opened up.
In addition, the doors on the AFW pump rooms need to be opened during an SBO. These doors open into the turbine l
building which is both larger and cooler than the AFW pump room.
Review of Licensee's Subaittal The licensee evaluated area temperatures for nine different l
locations of the plant. However, the licensee provided results for only two areas, namely the AFW pump room and the control room.
The licensee did not indicate what the final temperature would be l
in the control room after the removal of portions of drop ceiling.
Since the air conditioning to the shared control room can only be operational when either of the EDGs supporting emergency buses 11 or 24 is operating, the licensee can not take credit for the availability of air conditioning during the first hour of an SB0 j
l event. After one hour, the AAC power source can supply power to j
the control room air conditioning unit. Therefore, the licensee f
15 i
a
.~
needs to justify why there is no mention of opening the control room cabinet doors within 30 minutes as guided in NUMARC 87-00 Supplemental Questions / Answers.
Although the licensee's submittal dated March 30, 1990 (13) identified different methods which were used for calculating area temperatures, it did not provide sufficient justification for us to concur.
Specifically, the licensee needs to explain the term
" partial average" of walls of greater than 8" thick, and show the method used for taking " partial credit of filled wall."
- Further, the licensee needs to provide the results of the nine area heat-up calculations and reasoning why they should not be considered as dominant areas of concern.
Finally, the licensee needs to verify that the areas containing heat generation sources have appropriate area cooling, or provide 8-hour heat-up calculations showing that the equipment operability will not be affected by the loss of ventilation.
It should be mentioned that the generic NUMARC 87-00 methodology can not be used for 8-hour heat-up calculations.
5.
Containment Isolation Licensee's Submittal The licensee reviewed the plant list of containment isolation valves (CIVs) to verify that valves which must be capable of being closed or operated (cycled) under station blackout conditions can be positioned (with indication) independent of the preferred and blacked-out unit's class IE power supplies. The licensee stated that no plant modifications are necessary to ensure that appropriate containment integrity is provided under SB0 conditions.
l 16 i
Review of Lic'nsee's Submittal e
To determine which containment isolation valves (CIVs) require either manual or' power operated closure capability the list of containment isolation valves given in Figure 5-10 of the plant UFSAR was reviewed.
Excluding those CIVs that conform to the criteria stated in Regulatory Guide 1.155, Section 3.2.7, it was determined that appropriate containment integrity is obtainable without any operator action.
6.
Reactor Coolant Inventory Licensee's submittal The licensee stated that a plant-specific analysis has been used to assess the plant's ability to maintain adequate RCS inventory f
to ensure the core is cooled during a 4-hour SB0 event.
The licensee concluded that the expected rates of reactor coolant inventory loss under S80 conditions do not result in core uncovery
)
during an SBO,.and that the make-up systems are not required to maintain core cooling under natural circulation including reflux boiling.
i Review of Licensee's Submittal l
l The RCS losses which the licensee needs to consider during an SB0 are:
1.
25 gpa per pump losses through reactor coolant pump seals l-per NUMARC guidelines, and 2.
maximum allowed RCS leakage per plant technical specifications.
i f
17
i Each unit at CCNPP is equipped with four reactor coolant pumps resulting in an assumed seal leak rate of 100 gpm.
The technical specification maximum allowable leakage (sum of identified and unidentified) is estimated to be 12 gpm.
Therefore, if no RCS cooldown is attempted, the licensee needs to assume an RCS inventory loss of at least 112 gpm during an SB0 event.
The make-up, or charging system at each unit consists of three 44 gpm capacity positive displacement charging pumps. A review of the j
plant UFSAR indicates that two charging pumps can be powered from one EDG.
Since the AAC power source is available within one hour, the charging pumps can provide a maximum RCS make-up of 88 gpm if the RCS cooldown is minimized and the RCS pressure is kept above 1275 psia.
(The 1275 psia is the shutoff head of the high head injection (HHI) pumps.)
If the licensee decides to initiate RCS cooldown to lower the RCS pressure below 1275 psia, then an HHI pump with a capacity of 350 gpm can be used to maintain the RCS inventory.
Based on the above, if the RCS cooldown is minimized, then j
3 approximately 2,900 ft of RCS inventory will be lost due to the assumed leakages during an 8-hour SB0 event. Our analytic experience with similar plants indicates that an RCS inventory 3
loss of 2,900 ft will not uncover the core. However, the licensee needs to have an analysis which conforms with the above assumptions in its documentation supporting the SB0 submittal.
3.4 Proposed Procedures and Training Licensee's Submittal The licensee stated that the following plant procedures have been reviewed and modified, if necessary, to meet the guidelines in NUMARC 87-00, Section 4:
18
~
1.
Station blackout response guidelines, 2.
AC power restoration, and 3.
Severe weather.
In addition, the licensee stated that the plant emergency operating procedures will be revised to require different actions on whether the spare diesel is aligned to act as an AAC power source or to be a replacement EDG to a single unit.
Review of Licensee's Submittal We neither received nor reviewed the affected SB0 procedures. We consider these procedures as plant specific actions concerning the required activities to cope with an SBO. We believe that it is the licensee's responsibility to revise and implement these procedures, as needed, to mitigate an SB0 event and to assure that these procedures are complete and correct, and that the associated training needs are carried out accordingly.
3.5 Proposed Modifications Licensee's Submittal The licensee proposes to add two class 1E diesel generators to the three existing EDGs resulting in a two dedicated EDG per unit with the fifth diesel acting as a spare.
In addition, the licensee plans to modify the spare EDG to be used as an AAC power source.
The licensee added that l
the size and the scope of this project requires a schedule of approximately five years duration before it can be completed. A more l
complete schedule will be provided after the issuance of notification of acceptance by the NRC staff.
i The licensee also plans to perform the following modifications:
19
l I
w o
repower the power operated relief valves (PORVs) from the batteries, o
repower the PORY block valves from the batteries, o
repower one channel of the reactor vessel level monitoring system (RVLMS) from the batteries, o
open up 30% of the control room drop ceiling, and o
repower various control room indicator lights from the batteries.
l Further, the licensee intends to perform a modification to the battery l
rooms HVAC systems to ensure that these room temperatures will not fall j
bellow a minimum temperature which was used in the battery sizing calculations.
l The licensee stated that a schedule for completic.1 of these modifications will be provided after the issuance of the SB0 safety evaluation report by the NRC.
Review of Licensee's Submittal The proposed modifications appears to conform with the guidance provided in NUMARC 87-00 and RG 1.155. However, the licensee needs to provide additional technical information regarding these modifications for the NRC's review. The modifications to repower the control room indicator lights, PORVs, PORY block valves, and RVLMS from the class IE batteries greatly enhances the operators ability to mitigate possible situations I
during an SB0 event.
Removal of portions of the control room drop ceiling allows consideration of a larger heat sink for dissipating the heat generation in this room during an SBO. With regard to the battery room HVAC modification, in the absence of any technical information, we believe the licensee's decision to be valid and justified.
20
l J
3.6 Quality Assurance and Technical Specifications The licensee did not provide any information concerning the conformance of the plant's SB0 equipment to the guidance of RG 1.155, Appendices A and 8.
i I
I l
l i,
4 I
21
r-i
4.0 CONCLUSION
S Based on our review of the licensee's submittal and the information available in the UFSAR for Calvert Cliffs Nuclear Power Plant Unit Nos. I and 2, we find that the submittal conforms with the requirements of the SB0 rule l
and the guidance of RG 1.155 with the following exceptions:
1.
Offsite Power Design Characteristics l
The licensee's submittal states that the expected grid-related LOOP at the site is less than one in 20 years. However, the licensee did not consider a recent LOOP event which appears to be grid-related.
This event, which occurred on July 23, 1987, lasted nearly two hours and caused both units to trip upon loss of all offsite power sources.
Since this grid-related event has occurred in an operating history of less than 20 years, the CCNPP offsite power design characteristic group is "P3."
This classification in conjunction with the selected EDG target reliability of 0.975 requires an SB0 cope duration of eight hours.
2.
Alternate AC Power Source Although the proposed AAC power source appears to meet the criteria given in NUMARC 87-00, Appendix B, the licensee needs to I
provide technical information detailing the needed modifications for the NRC's review.
In addition, the licensee needs to perform a test demonstrating that the required safe shutdown equipment can be powered within one hour of an SB0 event.
3.
Effects of Loss of Ventilation The licensee stated that different methods were used for the heat-up calculations at CCNPP. However, it did not provide sufficient i
justification for us to concur. Specifically, the licensee needs to explain the term " partial average" of walls of greater than 8" l
22 N
ts
- ~
~,
5.0 REFERENCES
1.
The Office of Federal Register, " Code of Federal Regulations Title 10 Part 50.63," 10 CFR 50.63, January 1, 1989.
2.
U.S. Nuclear Regulatory Commission, " Evaluation of Station Blackout Accidents at Nuclear Power Plants - Technical Findings Related to Unresolved Safety Issue A-44," NUREG-1032, Baranowsky, P. W., June 1988.
3.
U.S. Nuclear Regulatory Comission, " Collection and Evaluation of Complete and Partial Losses of Offsite Power at Nuclear Power Plants,"
NUREG/CR-3992, February 1985.
4.
U.S. Nuclear Regulatory Comission, " Reliability of Emergency AC Power System at Nuclear Power Plants," NUREG/CR-2989, July 1983.
5.
U.S. Nuclear Regulatory Comission, " Emergency Diesel Generator Operating Experience, 1981-1983," NUREG/CR-4347, December 1985.
6.
U.S. Nuclear Regulatory Comission, " Station Blackout Accident Analyses (Part of NRC Task Action Plan A-44)," NUREG/CR-3226, May 1983.
7.
U.S. Nuclear Regulatory Comission Office of Nuclear Regulatory Research, " Regulatory Guide 1.155 Station Blackout," August 1988.
8.
Nuclear Management and Resources Council, Inc., " Guidelines and Technical Bases for NUMARC Initiatives Addressing Station Blackout at Light Water Reactors," NUMARC 87-00, November 1987.
9.
Nuclear Safety Analysis Center, "The Reliability of Emergency Diesel Generators at U.S. Nuclear Power Plants," NSAC-108, Wyckoff, H.,
September 1986.
10.
Creel, G. C., letter to the Document Control Desk of the U.S. Nuclear Regulatory Comission, "Calvert Cliffs Nuclear Power Plant Unit Nos.1 &
24 3