ML20078C217
| ML20078C217 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs  |
| Issue date: | 10/24/1994 |
| From: | Denton R BALTIMORE GAS & ELECTRIC CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| REF-GTECI-A-47, REF-GTECI-SC, TASK-A-47, TASK-OR GL-89-19, TAC-M74923, TAC-M74924, NUDOCS 9410280227 | |
| Download: ML20078C217 (4) | |
Text
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I Rontxt E. DYNTos Baltimore Gas and Electric Company Calvert Clip Nuclear Power Plant Vic e President 1650 Calvert Clif]s Parkway Nuclear Ener>n~
Lusby, Alanland20657 410 586-2200 Ert. 4455 local 410 260 4455 Baltimore j
October 24,1994 U. S. Nuclear Regulatory Commission Washington, DC 20555 ATTENTION:
Document Control Dest:
SUBJECT:
Calvert Cliffs Nuclear Power Plant Unit Nos.1 & 2; Docket Nos. 50-317 & 50-318
{
NRC Generic Letter 89-19, " Request for Action Related to Resolution of Unresolved Safety Issue A-47 ' Safety Implication of Control Systems in LWR Nuclear Power Plants' Pursuant to 10 CFR 50.54(f)," Response to Request for A_dditional Informatiqn (TAC Nos. M74923 & M74924)
Reference (a) states that the NRC has completed their review of Reference (b) and concluded that the recommendations of Generic Letter (GL) 89-19 are met without installing an automatic overfill protection system if certain conditions are verified. These conditions are as follows:
1.
Appropriate operator training and procedures to address steam generator (SG) overfill events and small-break loss-of-coolant-accidents (SBLOCAs) have been implemented;
- and, 2.
An evaluation to confinn the applicability of the CEOG analyses (Reference b) to Calvert Cliffs has been performed.
Reference (a) requests that Baltimore Gas and Electric Company (BGE) respond to the above two items.
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9410280227 941024 PDR ADOCK 05000317 P
PDR l
Document Control Desk October 24,1994 Page 2
RESPONSE
l.
Procedures and Trainine SBLOCA Based on the recommendations of Reference (c), BGE included appropriate enhancements in Emergency Operating Procedure (EOP)-5, " Loss of Coolant Accident," to address the SBLOCA concern of GL 89-19. The Licensed Operator Requalification program trains the licensed operators on the basis of EOP-5. Simulator training and evaluation scenarios reinforce the procedural direction given in EOP-5.
SG Overfill The dominant accident scenario for core melt risk identified in NUREG/CR 3958 (Reference d) is a SG overfill causing a main steam line break (MSLB) followed by a SG tube rupture of one or more tubes.
Abnormal Operating Procedure (AOP)-?G, " Malfunction of Main Feedwater System," and EOP-0, " Post-Trip immediate Actions," contain steps to prevent a SG overfill event from occurring by directing operator action for a SG overfeed malfunction or other excessive feedwater event. In the event of both a SG tube rupture and an MSLB, regardless ofits cause, EOP-8, " Functional Recovery Procedure," contains appropriate steps to mitigate the event.
Recall that the Functional Recovery Procedure is Combustion Engineering's syrnptom based procedure. As discussed in Reference (c), all multiple emergency events are mitigated by directing operator action, based on plant symptoms, to address safety parameters. For Combustion Engineering plants, procedures are not developed to address individual combinations of multiple events.
The Licensed Operator Requalification program trains the licensed operators on the basis of the Steam Generator Tube Rupture procedure. The key elements in this event mitigation strategy are depressurizing the Reactor Coolant System (RCS) and commencing an RCS cooldown in order to facilitate isolation of the faulted generator and to enable RCS depressurization to continue. This strategy minimizes the tube leakage and will be continued until shutdown cooling is entered. In addition to routine basis training, simulator training and evaluation scenarios are used to ensure that the operators are able to implement this strategy during single and multiple emergency event scenarios. The Licensed Operator Requalification program also trains the licensed operators on SG overfill conditions. This training reinforces the procedural direction of AOP-3G and EOP-0.
2.
Applicability of CEOG Analyses The majority of the CEOG analyses (Reference b) involves using the revised data from the final NUREG-0844 (Reference f) to develop more realistic assumptions for NUREG/CR-3958. The CEOG analyses show that if the more realistic assumptions are used to reproduce the analysis of NUREG/CR-3958, then the GL 89-19 recommended changes are not justified for CE plants.
Since NUREG/CR-3958 was applicable to BGE with data from the draft NUREG-0844, the i
Docuraent Control Desk October 24,1994 Page3 CEOG analyses are also applicable to BGE since the only change is that the CEOG analyses use data from the final NUREG-0844 The plant-specific aspects of the CEOG analyses are the MSLB location and credit for operator recovery actions. For Calvert Cliffs Units 1 and 2, the analyses are applicable since a majority of the main steam piping upstream of the main steam isolation valve is located inside containment and, as described in Item 1. above, procedures have been developed to direct operator recovery actions for multiple emergency events. There is sufficient refueling water storage tank inventory to allow completion of the operator actions described in the procedure.
Should you have any further questions regarding this matter, we will be pleased to discuss them with you.
Very truly yours,
- for R. E. Denton Vice President - Nuclear Energy DFD/JMO/dlm cc:
D. A. Brune, Esquire J. E. Silberg, Esquire L. B. Marsh, NRC D. G. Mcdonald, Jr., NRC T. T. Martin, NRC P. R. Wilson, NRC R.1. McLean, DNR J. H. Walter, PSC
Document Control Desk October 24,1994 Page 4 W
REFERENCES:
(a)
Letter from Mr. D. G. Mcdonald, Jr. (NRC) to Mr, R. E. Denton (BGE),
dated September 21,1994, Transmittal of the NRC Safety Evaluation Report for the Combustion Engineering Owners Group Response to Generic Letter 89-19, Request for Action Related to Resolution of Unresolved Safety Issue A-47 ' Safety Implications of Control Systems in LWR Nuclear Power Plants' Pursuant to 10 CFR 50.54(f), and Request for Additional Information - Calvert Cliffs Nuclear Power Plant, Unit Nos.1 & 2 (TAC Nos. M74923 & M74924)
(b)
Letter from Mr. L L Hutchinson, Chairman - Combustion Engineering Owners Group (CEOG) to Mr. S. F. Newberry (NRC), dated October 31,1990, NRC Generic Letter 89-19, CEOG Concerns Regarding Steam Generator Overfill Protection (SGOP)
(c)
Letter from Mr. P, R. Nelson to CEOG Task 651 Participants, dated November 5,1990, Partial Response to NRC Generic Letter 89-19, Small Break LOCA Recovery with Low Head HPSI (d)
NUREG/CR-3958, Effects of Control System Failures on Transients, Accidents and Core-Melt Frequencies at a Combustion Engineering Pressurized Water Reactor, Pacific Northwest Lab, March 1986 (c)
Combustion Engineering Emergency Procedure Guidelines (CEN-152, Revision 03), dated May 1987 (f)
NUREG-0844, NRC Integrated Program for the Resolution of Unresolved Safety Issues A-3, A-4, and A-5 Regarding Steam Generator Tube Integrity, April 1985 (draft) or September 1988 (final) i
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