ML20116E819
| ML20116E819 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs  |
| Issue date: | 01/31/1991 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20116D885 | List:
|
| References | |
| FOIA-96-237 NUDOCS 9608060133 | |
| Download: ML20116E819 (10) | |
Text
. _.
8 UNITED STATES
[
g NUCLEAR REGULATORY COMMISSION 7e
[
WASHINGTON. D. C. 20555 k*..**,/
ENCLOSURE 1 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION i
STATION BLACK 0UT SUPPLEMENTAL SAFETY EVALUATION BALTIMORE GAS AND ELECTRIC COMPANY CALVERT CLIFFS NUCLEAR POWER PLANT DOCKET NOS. 50-317/318
1.0 INTRODUCTION
l The NRC staff's Safety Evaluation (SE) pertaining to the licensee's initial 1
responses to the Station Blackout (SBO) Rule, 10 CFR 50.63, was transmitted to the licensee by letter dated October 10, 1990. The staff found the licensee's proposed method of coping with an SB0 to be acceptable, subject to the satis-factory resolution of several recossendations which were itemized in the staff's SE. The licensee responded to staff's SE, and specifically to the recossen-dations, by letters from G. C. Creel, Baltimore Gas and Electric, to the Document Control Desk, U. S. Nuclear Regulatory Commission, dated November 13,
)
1990 and December 13, 1990.
2.0 EVALUATION
The licensee's responses to each of the staff's recommendations are evaluated below.
2.1 Station Blackout Duration SE Reconmendation:
The licensee should reevaluate the plant's ability tocopewithaStationBlackout(560)basedonan8-hourcopingduration and include these analyses with the other documentation supporting the SB0 submittal.
If the licensee desires reconsideration of the coping category, sufficient justification with appropriate analysis should be provided for staff review which demonstrates the rational for the July 23, 9608060133 960731 PDR FOIA 8
DINICOL96-237 PDR l
l i
[ l l
1987 loss of offsite power (LOOP) not being considered symptomatic of a i
grid related LOOP.
l Licensee Response:
The licensee presented a description of the LOOP event and the changes made to prevent a reoccurrence of the event to justify that the event was plant centered and was not symptomatic of a grid related LOOP. The licensee stated the LOOP was initiated by a ground fault that occurred on one of the two 500 kV lines connecting the plant to theBaltimoreGasandElectric(BG8E) grid. The ground fault was caused by a tree that had been identified during previous surveys as one which needed to be cut. However, due to lack of resources, the tree was not cut j
down immediately. The licensee stated that corrective actions have been I
taken by increasing expenditures for right of way clearing, cutting down all identified trees and increasing patrols to detect early tree growth.
l The line to ground fault correctly resulted in the opening of both breakers at the ends of the faulted line. However, due to a defective transistor on a logic circuit card, the fault incorrectly caused the opening of the breakers on the Calvert Cliffs end of a second 500 kV line, resulting in the isolation and tripping of the Calvert Cliffs Plant. The licensee notes that the grid was still intact and that the July 1987 event did not cause, nor was it caused, by a loss of the BG8E grid.
The licensee stated that the faulty logic card is a component of one of many relays used throughout BG&E's 500/230 kV system. The cards used in i
the protective relay circuits are tested every 18-24 months, failures in these cards have not occurred anywhere else at BG&E generating stations, and the protective relays have provided reliable service since they were first installed in 1968. The failed transistor is one of nine identical transistors on the timing circuit card. Although some of the other tran-l sistors on the card are more electrically exposed than the failed tran-sistor, they did not fail. For the above reasons, the licensee classifies I
l
. this failure as a random equipment failure and not a grid related event or the result of inadequate surge protection at the plant.
Based on the above, we accept the licensee's justification that the July 1987 LOOP event was not symptomatic of grid instability, and that appropriate actions have been taken to provide reasonable assurance that such an event will not occur again. Therefore, we agree with the licensee's determination that the plant has an offsite power design characteristic group of "P2," rather than "P3," with a required coping duration of 4-hours rather than 8-hours.
2.2 Proposed AAC Power Source 1
SE Reccamendations:
1.
The licensee should submit separately for staff review the overall design information on the proposed EDG modifications and instal-lation of the additional EDGs. This information should include the modifications to the EDGs' busses, cables and associated systems.
ThelicenseeshouldalsoincludeinformationontheEDG(spare)when used as an AAC source and when substituted for a dedicated EDG when it is out for maintenance and repair. LC0 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 documen-tation supporting the SB0 submittal maintained by the licensee.
2.
The licensee should demonstrate that the AAC source is available for supplying the SB0 loads within one hour of the onset of the SB0 event by conducting the appropriate testing in accordance with the guidance of NUMARC 87-00, Appendix B, Item B.12.
I i
~
\\
. Licensee Response: The licensee committed to supply information concerning the overall design of the additional diesel generators as a part of the l
licensing process once vendors and a final design are selected. Use of the spare (alternate AC source / Class 1E backup) diesel will be described, and technical specifications will be submitted to include the new diesel arrangement in the Limiting Conditions of Operation and Surveillance l.
Requirements. The spare diesel will be tested on a one-time basis to ensure it can meet its AAC function in accordance with the guidance of l
NUMARC 87-00, Appendix B, Item B.12. A description of the diesel generator modifications and installation will also be maintained with the other 5B0 I
I documentation.
I We find the above described licensee's comitments to be acceptable.
It l
is understood that (1) the modifications associated with the existing EDG l-as well as the new EDGs will be submitted for staff review and (2) that the documentation associated with the testing of the AAC source will be maintained with the other SB0 documentation.
2.3 Condensate Inventory For Decay Heat Removal L
SE Recossendation: The licensee should confirm that there is sufficient inventory to remove the decay heat from both units and also provide for cooldown in the-non-blacked-out (NBO) unit and include this confirmation in the documentation supporting the SB0 submittal maintained by the licensee.
1 i
Licensee Response: The licensee stated that the condensate inventory calculations have been reviewed and that sufficient inventory exists to support both the blacked-out and the non-blacked-out unit in Hot Standby i
during the four-hour SB0 event.
Further, this calculation is included with the other 500 documentation.
4 j
We find this to be acceptable.
1
~,
2.4 Compressed Air 1
i SE Recommendation: The licensee should establish procedures and simulate appropriate action and provide operator training to assure that the decay l
heat removal can be adequately maintained during the first hour of an SB0 i
event.
Licensee Response: The licensee states that Emergency Operating Procedure (EOP-7) has been established which describes operator actions during an SB0 event, and that operator training, as well as simulator training, has taken place to ensure that the operators can adequately l
respond to an SB0 event.
l The licensee notes that the atmospheric dump valves (ADVs), not the power l
operated relief valves (PORVs), are used to remove heat from the steam generators. The PORVs, on the pressurizer, and the PORY block valves, will be provided with DC power to control pressure and to block leakage on the reactor coolant system.
l We find that the licensee has adequately addressed the staff's concerns pertaining to the E0P and training for the decay heat removal function during an SBO. We also accept licensee's clarification pertaining to the ADYs and PORVs.
2.5 Effects of Loss of Ventilation 1
l SE Recommendation: The licensee should reanalyze the heatup analyses for j
areas of concern based on a one-hour duration, including information to demonstrate the acceptability of the methodology, assumptions, and initial conditions used in the calculations. This assumes HVAC for dominant areas of concern will be powered by the AAC source after one hour. Also, the licensee should document additional justification as to why it is not necessary to open cabinet doors in the control room within one-half hour l
\\
l t
1 l
l
\\
, 1
)
l after the onset of an SB0 event. The licensee should include the above l
analyses and results in the documentation supporting the 580 submittal i
i maintained by the licensee.-
]
l Licensee Response:
The licensee presente.d a tabulation, showing the temperature conditions after 4-hours following the onset of an SBO, for
.nine rooms containing S80 equipment. The calculations were based on the NUMARC 87-00 Section 7.2.4 methodology where applicable, and on other methodology where the NUMARC method was not considered to be applicable due to plant specific characteristics. The licensee' presented a des-l cription of the plant specific methodology used for the various rooms, and i
the assumptions used for these calculations. The 4-hour calculations were considered bounding for those rooms that will have HVAC powered by the AAC l
source after one hour. The values for the control and data acquisition l
system (DAS) rooms were based on a modified ceiling configuration opened l
to allow better air circulation. The emergency operating procedures are to be' revised to ensure that the front of the control room panels are to l
be opened within 30 minutes of the onset of an 580.
The licensee stated that three of the nine rooms analyzed (Main Steam Piping Penetration Room, East Piping Penetration Room, and AFW Pump Room) l have fire pro-tection systems that actuate at high temperatures, but the temperatures in these rooms will be well below the setpoints at which fire protection would be actuated.
j We have reviewed the methodology and assumptions used for calculating the j
temperature values in the nine areas containing SB0 equipment and find them to be acceptable.
It is understood, based on the licensee's original April 14, 1989 submittal, that reasonable assurance of the operability of l
SB0 response equipment in these areas have been assessed for the calculated temperature values expected.
..e..
1
- l l
2.6 Reactor Coolant Inventory SE Reconnendation: The licensee should perform the necessary analyses to show that a reactor coolant inventory loss of 112 gpa does not result in core uncovery during an eight-hour S80' event. The licensee should include these analyses and results in the documentation supporting the S80 submittal maintained by the licensee.
Licensee Response:
The licensee stated, based on a leakage of 25 gpa per reactor coolant pump, 10 gpa identified leakage, 10 gpa miscellaneous l
leakage, and an additional letdown flow of 128 gpm for the first 30 minutes of 'the event, that no core uncovery would occur during a four hour SB0 event. The licensee stated that the assumptions and results of the analysis are maintained as part of the 580 documentation.
We find the licensee's response to be consistent with the staff's recommendation.
2.7 Proposed Modifications SE Recommendation:
The licensee should provide a full description in-cluding the nature and objectives of the required modifications identified above in the documentation supporting the S80 submittal that is to be maintained by the licensee.
It should be noted that the modifi;ations relating to the reconfiguration of the existing EDGs and the addition of two others have not been reviewed under the SB0 review and should be sub-mitted separately for staff review as indicated in the recommendations in Section 2.2.
1 Licensee Response: The licensee stated that a full description cf each proposed modification (except the additional EDGs) and the objectives of the modification will be included in the documentation. The description of the additional EDGs are to be provided to the NRC for review as a my..
m.,%
4
?
. separate package. The modifications are to be completed during the next Unit 1 and Unit 2 refueling outages. The EDGs are expected to become operational in February 1995.
Wi find the licensee's response to be consistent with the staff's recommendation, with the understanding that the modifications associated with the existing EDG as well as the new EDGs will be included for staff l
review.
2.8 Quality Assurance and Technical Specifications SE Recommendation:
The licensee should implement a quality assurance l
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.
l Licensee Response: The licensee stated that a QA program that meets the guidance of Regulatory Guide 1.155, Appendix A, is being developed to cover equipment needed for an SB0 and not presently covered by an existing QA program. The licensee expects the program to be implemented by the end of 1991.
We find the licensee's response to be consistent with the staff's recommendation and therefore to be acceptable.
2.9 EDG Reliability Program SE 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 SB0 submittal that is to be maintained by the licensee.
Licensee Response:
The licensee stated that they have connitted to a l
reliability of 0.975, that the program will meet the guidance of RG 1.155, i
i
4 Section 1.2, and that the reliability program will be fully implemented by September 30, 1991.
We find the licensee's cosmitment to be acceptable.
3.0 SUlmARY AND CONCLUSION The NRC staff's Safety Evaluation (SE) pertaining to the licensee's initial responses to the Station Blackout (SBO) Rule,10 CFR 50.63, was transmitted to the licensee by letter dated October 10, 1990. The staff found the licensee's proposed method of coping with an SB0 to be acceptable, subject to the satis-factory resolution of several recommendations which were itemized in the staff's SE. The licensee's responses to each of the staff's reconnendations have been evaluated in this Supplemental Safety Evaluation (SSE) and found to be acceptable.
However, the staff has stated some " understandings" in this SSE which the licensee should review and respond to, if their understanding is different than the staff's. These understandings are that (1) the modifications associated with the existing EDG (as well as the new EDGs) will be submitted for staff review, (2) that the documentation associated with the testing of the AAC source will be maintained with the other SB0 documentation, and (3) for the calculated temperature values expected in the nine areas containing 580 equipment, that reasonable assurance has been assessed of the operability of SB0 response equipment. Also the reactor coolant inventory evaluation discussed in the staff's October 10, 1990, SE was based on the guidance provided in NUMARC 87-00 of 25 gpm per reactor coolant pumps (RCP) seal leakage for pressurized water reactor. The 25 gpm value was agreed to between NUMARC and the staff pendingresolutionofGenericIssue(GI)23.
If the final resolution of GI-23 defines higher RCP leakage rates than assumed for this evaluation, the licensee should be aware of the potential impact of this resolution on their analyses and actions addressing conformance to the SB0 rule.
~
ENCLOSURE 2 SALP INPUT FACILITY NAME:
Calvert Cliffs
SUMMARY
OF REVIEW:
The licensee responded to staff's Safety Evaluation pertaining to the licensee's proposed method for complying with the Station Blackout Rule (10 CFR 50.63) by letters dated November 14, 1990, and December 13, 1990. The NRC staff found the licensee's responses to be acceptable.
NARRATIVE DISCUSSION OF LICENSEE PERFORMANCE FUNCTIONAL AREA: ENGINEERING / TECHNICAL SUPPORT:
The licensee's responses were clear and responsive to staff's concerns dis-playing a good technical understanding of the safety issues involved and ade-quate management control.
Author:
A. Toalston l
Date:
January 9,1990 l
i