ML20035F138
| ML20035F138 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 04/14/1993 |
| From: | James Anderson Office of Nuclear Reactor Regulation |
| To: | Opeka J CONNECTICUT YANKEE ATOMIC POWER CO., NORTHEAST NUCLEAR ENERGY CO. |
| References | |
| NUDOCS 9304200314 | |
| Download: ML20035F138 (9) | |
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WASmNGTON. D C. M55 OM E.....f April 14, 1993 v
q Docket No. 50-245 Mr. John F. Opeka tixecutive Vice President, Nuclear Connecticut Yankee Atomic Power Company Northeast Nuclear Energy Company Post Office Box 270 Hartford, Connecticut 06141-0270
Dear Mr. Opeka:
SUBJECT:
MILLSTONE UNIT 1 - REVIEW 0F ISAP SUBMITTAL DATED OCTOBER 23, 1992 (TAC M83573)
In a letter dated October 23, 1992, Northeast Nuclu Energy Company (NNECO) submitted to the NRC an updated report on the Millstone Unit No. 1 Integrated Safety Assessment Program (ISAP).
In accordance with the Program Plan identified in Amendment No. 56 for Millstone Unit No.1, the NRC had 60 days from receipt of the letter to state whether or not the staff concurred with NNECO's positions stated in the report.
In a letter dated December 30, 1992, the NRC staff issued its review of all the ISAP topics.
There are currently 133 topics covered under ISAP. NNECO's October 23, 1992, ISAP submittal stated that NNECO considered 27 topics to be open. Of these 27 topics, 2 are currently under NRC staff review, Topic 1.09 (Regulatory Guide 1.97) and Topic 1.121 (hydrogen monitor redundacy). The remainder of the 27 open topics are awaiting NNECO implementation or evaluation.
NNEC0's October 23, 1992, letter also indicated that the other 106 topics have either been closed out by NRC documentation or are ready for closure. The staff has reviewed the 106 topics, and in the letter dated December 30, 1992, concluded that 92 of the topics were resolved and that the remaining la inpics were still under staff consideration. The NRC staff has reviewed the 14 remaining topics and has concluded that 3 should remain open due to ongoing staff review and the remaining 11 are closed. lists the 14 topics and the NRC staff's review of them.
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Mr. John F. Opeka Therefore, of the 133 total ISAP topics, the NRC staff has concluded that 30 should remain open within ISAP, and 103 are resolved. This completes the NRC's review of NNEC0's ISAP submittal dated October 23, 1992. The next ISAP report is scheduled to be submitted in May 1993.
Further NRC revies of closed ISAP topics, if any, will be performed by inspection or audit. The NRC staff remains available to discuss these issues with you.
Sincerely, Original signed by James W. Andersen, Acting Project Manager Project Directorate I-4 Division of Reactor Projects - I/II Office of Nuclear Reactor Regulation
Enclosure:
As stated cc w/ enclosure:
See next page Distribution:
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Document Name: G:\\ANDERSEN\\ISAPSUPP
Mr. John F. Opeka Therefore, of the 133 total ISAP topics, the NRC staff has concluded that 30 should remain open within ISAP, and 103 are resolved. This completes the NRC's review of NNECO's ISAP submittal dated October 23, 1992. The next ISAP report is scheduled to be submitted in May 1993.
Further NRC review of closed ISAP topics, if any, will be performed by inspection or audit. The NRC staff remains available to discuss these issues with you.
Sincerely,
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/fJam s W. An'dersen, Acting Project Manager
/ Project Directorate I-4 Division of Reactor Projects - I/II Office of Nuclear Reactor Regulation
Enclosure:
As stated cc w/ enclosure:
See next page l
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Mr. John F. Opeka Millstone Nuclear Power Station Northeast Nuclear Energy Company Unit I cc:
Gerald Garfield, Esquire R. M. Kacich, Director Day, Berry and Howard Nuclear Licensing Counselors at Law Northeast Utilities Service Company City Place Post Office Box 270 Hartford, Connecticut 06103-3499 Hartford, Connecticut 06141-0270 W. D. Romberg, Vice President J. P. Stetz, Vice President Nuclear Operations Services Haddam Neck Plant Northeast Utilities Service Company Connecticut Yankee Atomic Power Company Post Office Box 270 362 Injun Hollow Road Hartford, Connecticut 06141-0270 East Hampton, Connecticut 06424-3099 Kevin McCarthy, Director Regional Administrator Radiation Control Unit Region I Department of Environmental Protection U.S. Nuclear Regulatory Commission State Office Building 475 Allendale Road Hartford, Connecticut 06106 King of Prussia, Pennsylvania 19406 Allan Johanson, Assistant Director First Selectmen Office of Policy and Management Town of Waterford Policy Development and Planning Division Hall of Records 80 Washington Street 200 Boston Post Road Hartford, Connecticut 06106 Waterford, Connecticut 06385 S. E. Scace, Vice President P. D. Swetland, Resident Inspector Millstone Nuclear Power Station Millstone Nuclear Power Station Northeast Nuclear Energy Company c/o U.S. Nuclear Regulatory Commission Post Office Box 128 Post Office Box 513 Waterford, Connecticut 06385 Niantic, Connecticut 06357 j
H. F. Haynes, Nuclear Unit Director G. H. Bouchard, Director l
Millstone Unit No. 1 Nuclear Quality Services Northeast Nuclear Energy Company Northeast Utilities Service Company Post Office Box 128 Post Office Box 270 Waterford, Connecticut 06385 Hartford, Connecticut 06141-0270 Nicholas S. Reynolds Winston & Strawn 1400 L Street, NW Washington, DC 20005-3502 i
NRC STAFF REVIEW 0F THE 14 REMAINING ISAP TOPICS WHiCH WERE NOT C0VERED IN THE NRC'S DECEMBER 30. 1992 LETTER Tooic 1.03 - Containment Isolation - Accendix A Modifications As part of the Millstone Unit 1 Systematic Evaluation Program (SEP) review (Topic VI-4), the isolation provisions for lines penetrating the primary containment were reviewed against the criteria of General Design Criteria (GDC) 54 through 57. As documented in the Integrated Plant Safety Assessment Report Supplement, all of the issues raised in SEP Topic VI-4 have been resolved, with the exception of the adequacy of the isolation provisions for penetration X-204, the cooling water return lines that branch off between takeoffs to the containment spray (CS) pumps.
In a letter dated 7/31/86, Northeast Nuclear Energy Company (NNECO) proposed to relocate the cooling water return line tie-in to the low pressure coolant injection (LPCI) suction line from upstream to downstream of pump suction valves 1-LP-2A and 28. NNECO also stated that relocating the tie-in would not reduce the core melt frequency but would reduce the release outside containment. However, since the pipe is only 3/4 inch, the expected release, given significant fuel damage followed by a break in this line, would be small compared to other sources.
In NUREG-ll84, the staff determined that the overall safety significance is low compared to other release pathways following an accident with fuel failure and concluded that the implementation priority of this topic should be low.
In a letter dated 8/4/87, NNECO evaluated this topic under Integrated Safety Assessment Program (ISAP) and found the priority ranking to be low due to ac31igible public safety benefit.
During the 1991 refueling and July 1992 outages, NNEC0 replaced the water-cooled LPCI and CS motors with air-cooled motors.
This modification I
eliminated the Appendix A concerns for containment penetration X-204, in that the cooling water lines in question were removed and the ends capped. The NRC staff has determined that this topic is no longer applicable and, therefore, is closed.
Topic 1.16 - 10 CFR 50. Accendix R Appendix R to 10 CFR 50 required licensees to establish a fire protection program at their nuclear power plants.
NNECO, as a result of their review, proposed exemption requests and identified 4 plant modifications.
By letter dated 11/6/85 the NRC staff issued an exemption to certain Appendix R requirements, partly based on the licensee's commitment to implement the 4 proposed modifications.
NNEC0, in a letter dated 11/21/85, informed the staff that they performed a revalidation of their initial Appendix R review.
In a letter dated 7/31/86, NNECO identified 8 additional items to be included under the scope of this topic.
In NNECO's ISAP letter dated 11/9/88, NNECO stated that all proposed modifications (12 total topics) had been completed except for several aspects of topic 1.16.6 (installation of a water curtain, protecting the turbine building floor supports and protecting the structural steel in the mezzanine area).
In the same letter, NNECO concluded that the remaining aspects of topic 1.16.6 are not necessary to comply with Appendix R and, therefore, are not going to be done. This topic is currently under staff review and, therefore, should remain open.
- Topic 1.23/1.25 - Grid Separation Procedures /Deoraded Grid Voltaae Procedures These topics encompassed a review and evaluation of the plant power supply system against the criteria of GDC-17 with regard to the ability of the plant to cope with a degraded grid voltage condition.
In a letter dated 9/27/91, the NRC staff concluded that the existing undervoltage protection scheme at Millstone 1 does not meet GDC-17 requirements and stated that NNEC0 should submit a detailed description of the split-logic design to be incorporated in Unit 1.
By letters dated 11/27/91, 12/20/91, and 4/27/92, NNECO submitted their preliminary design for review and in a letter dated 11/30/92 provided an overview of the final design. NNECO's letter stated that they plan to proceed with evaluating the modifications associated with implementing a split-logic design within ISAP. As with any ISAP topic, NNECO stated that the next step is developing a conceptual design with enough detail to perform &
comprehensive ISAP evaluation.
Following completion of the ISAP evaluation, the project will be scheduled for implementation in accordance with the ISAP program plan. The new ISAP topic (1.122) will encompass topics 1.23 and 1.25 and, therefore, the NRC agrees that topics 1.23 and 1.25 can be closed.
Topic 1.40 - Boltino Deoradation or Failure This topic encompassed the plant-specific resolution of Generic Issue (GI) 29, addressing in-service inspection for bolting degradation. NNECO submitted information to the staff, which as noted in NUREG-1184, the staff found acceptable.
In addition, NNECO committed to and completed a 100% visual inspection of all Class 2 and 3 anchors, including bolts, during the 1987 refueling outage.
In NUREG-ll84, the staff made a recommendation for a walk-down checklist to reinforce the need for more frequent visual examinations.
NNEC0, in a letter dated 9/29/89, committed to evaluate this as a level-of-effort activity if plant-specific concerns arise and, therefore, consider this topic closed.
In NRC Inspection Report 50-245/91-24, dated November 26, 1991, the NRC inspector and NNEC0 discovered several loose anchor bolts on air handling units which are important te safety. The inspector conclucLd that the long-term corrective action plan for Millstone I anchor bolts was an unresolved item. The staff has determined tnat this topic should remain open l
until the concerns identified in Inspection Report 50-245/91-24 (unresolved i
item 50-245/91-24-03) are addressed.
Topic 1.107 - Drywell Soray Flow Indication This topic addresses drywell spray flow indication as it pertains to Regulatory Guide (RG) 1.97.
In a letter dated 10/23/92, NNECO reiterated that it believes that spray flow indication is not riaeded to carry out emergency operating procedure instruction and therefore no modifications are needed.
The NRC staff is currently reviewing NNEC0's latest submittals concerning RG 1.97 and tracking the review under TAC M51106, therefore, the staff agrees that this ISAP topic can be closed.
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Topic 1.108 - Torus Vacuum Breakers This topic addressed concerns associated with results of other plant reviews conducted in response to Generic Letter (GL) 88-14, " Instrument Air Supply System Problems Affecting Safety-Related Equipment." Unit I containment is configured with two redundant vacuum breaker relief lines from the torus to the reactor building.
Each line has an air-operated butterfly valve and a check valve.
Since the air-operated butterfly valves fail open on a loss of air or AC power, the specific concern relates to their inability to function as the second valve of the two valve containment isolation function. NNEC0 l
performed an analysis to determine the maximum possible benefit that could be derived from resolving this issue.
In a letter dated 11/30/90, NNECO stated that the project received a very low score and ranking. Therefore, NNECO concluded that the project was not warranted and the topic should be closed.
This topic is under staff review and, therefore, should remain open.
Topic 1.114 - Individual Plant Examinations. GL 89-20 This topic encompassed the plant-specific response to GL 88-20, " Individual Plant Examination for Severe Accident Vulnerabilities," issued on 11/23/88.
By letter dated 3/31/92, NNEC0 submitted its Individual Plant Examination (IPE) Report for Millstone 1.
The IPE did not identify any new major severe accident vulnerabilities which required immediate corrective action beyond those already completed or initiated. Therefore, NNECO considers this topic closed, since they fulfilled the requirements of GL 88-20.
The NRC staff is currently reviewing the IPE submittal and is tracking the review under TAC M74432.
Therefore, the staff agrees that ISAP topic 1.114 is closed.
Taoic 1.115 - Reactor Water level Reference Leo Break. GL 89-11 This topic was initiated due to the possibility of a reactor water level instrument sensing line break coupled with an additional independent single failure of a component in a control or protection system which was presented to all BWR owners via Generic Issue (GI) 101. The staff presented their analysis of this issue in GL 89-11 and concluded that the boiling water reactor design, in conjunction with operator training and procedures, provided adequate protection against this event.
GL 89-11 also requested that each licensee review the technical basis for this conclusion which was presented in NUREG/CR-5112.
NUREG/CR-5112 presented several design modifications but concluded that the alternatives were not cost effective because the total plant risk associated with the GI 101 concerns is relatively small and the cost of modifications is relatively high.
In addition, the NUREG stated that the plant designs provide an adequate measure of safety, in that they meet the emergency core cooling requirements as specified in the Standard Review Plan.
NNECO evaluated the possible alternatives and, in a letter dated 11/30/90, concluded that due to a very low ranking, no modifications would be scheduled and this topic should be closed. The NRC staff agrees that this topic can be closed.
. Topic 2.01 - LPCI Remotely Doerated Valves 1-LP-50A and B NNECO opened this topic to address a proposed project to provide for remote operation of torus drain valves 1-LP-50A and B.
it was envisioned by NNECO that the remote operation of these valves would allov the operator to perform a feed and bleed operation on the torus.
In a letter deted U/23/85, NNECO provided the Probablistic Safety Assessment (PSA) summary for this topic and also determined that the addition of remote operation capattiity for these valves and their associated downstream piping is too small to be considered for a potential torus bleed-and-feed long-term decay heat removal scheme. The staff reviewed the PSA summary and, as stated in NUREG-1184, concluded that the impact of the proposed modification, both positive and negative, is insignificant. Therefore, providing remote operators for valves 1-LP-50A and i
B would provide little if any benefit.
In NNECO's 8/4/87 ISAP report, NNECO i
concluded that due to the low public safety benefit and other considerations that this project should be dropped and the topic closed out. The NRC staff agrees that this topic can be closed.
Topic 2.02 - Drywell Mumidity Instrumentation NNECO opened this topic to address the installation of a sophisticated system which would continuously monitor primary containment leak rate.
In a letter i
dated 7/31/86, NNEC0 estimated that since existing leakage detection schemes employed at Millstone Unit I would be able to adequately detect small loss of coolant accidents (large loss of coolant accidents would be evident to operators very quickly by means of instrumentation) in about 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />, the addition of continuous drywell humidity instrumentation would provida only a small increase in public safety.
In a letter dated 8/4/87, NNECO stated that a continuous leak rate monitoring system would be very expensive, technically complicated, and may not work. Therefore, based on these determinations and the containment purge and vent recommendations (ISAP topic 2.25), NNEC0 proposed to drop this topic. The NRC staff agrees that this topic can be closed.
Topic 2.08 - Extraction Steam Pioina NNECO opened this topic to address the replacement of extraction steam piping.
The project was undertaken in response to a number of cases of severe erosion and failures of extraction steam piping at nuclear plants. Results from inspections showed that the 8th, 9th, and lith stage extraction steam piping from the low pressure turbine had substantial erosion degradation. NNECO replaced the piping in stages and in a letter dated 9/29/89, stated that all the piping had been replaced except for the extraction steam lines to the high pressure feedwater heaters which were scheduled for the cycle 14 refueling outage.
In a letter dated 10/23/92, NNECO stated that this project had been deferred based upon recent positive erosion / corrosion ultrasonic test results.
NNEC0 further stated that no modifications were necessary at this time and that the topic is resolved. NNECO intends to continue to monitor the system as part of the erosion / corrosion program.
The NRC staff agrees, that since the extraction steam piping is monitored as part of the erosion / corrosion program, that this topic can be closed.
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i Topic 2.17 - 4.16 kV. 480 V. and 123 VDC Plant Distribution Protection Study NNECO initiated this topic to conduct an extensive review of the 4.16 kV, 480 V, and 125 VDC plant distribution systems.
In the ISAP report dated 11/9/88, NNEC0 stated that the review was completed and that two 1
miscoordinations were identified that could not be rectified by a setting change. These miscoordinations concerned breakers in the 125 VDC plant 3
1 distribution system.
In the ISAP report dated 4/30/90, NNECO stated that upon i
further investigation into the miscoordinations have revealed that the i
existing design is adequate and no modifications were required. Therefore, i
NNECO considered this topic closed. The NRC staff agrees that this topic can l
be closed.
- l Topic 2.24 - Off-Site Power Systems i
NNECO opened this topic to address possible means for improving offsite power system reliability, capacity, and availability for Millstone Unit 1.
NNEC0 scheduled a study of this issue to determine any necessary modifications in light of the completion of the Unit 1/ Unit 2 backfeed.
In a letter dated 4
11/9/88, NNECO stated that the installation of a generator circuit breaker would keep the normal station service transformer in service as a source of offsite power following a turbine-generator trip. NNECO's ISAP evaluation of this project concluded that due to the very high implementation costs and only moderate safety. benefit that the project was not justified. Therefore, NNECO concluded that this topic was closed. The NRC staff agrees that this topic can be closed.
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