ML20029D381
| ML20029D381 | |
| Person / Time | |
|---|---|
| Site: | Nine Mile Point  |
| Issue date: | 04/27/1994 |
| From: | Sylvia B NIAGARA MOHAWK POWER CORP. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML20029D382 | List: |
| References | |
| NMP2L-1468, NUDOCS 9405050268 | |
| Download: ML20029D381 (3) | |
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I M V NIAGARA EYU MOHAWK NIAGARA MOHAWK PoWEn CoRPoRAT1oN /NINE MILE POINT, PO. BOX 63. LYCOM:NG, NY 13093/ TELEPHONE (315) 349-2882 B. Ralph SyMa Executive Vice President Nuclear April 27, 1994 NMP2L 1468 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555 RE: Nine Mile Point ' Unit 2 Docket No. 50-410 NPF-69 Gentlemen:
Niagara Mohawk Power Corix> ration (NMPC) hereby transmits an Application for Amendment to Nine Mile Point Unit 2 (NMP2) Operating License NPF-69. Also enclosed as Attachment A are the proposed changes to the Technical Specifications as set forth in Appendix A to the above mentioned license. Supporting information and an analysis demonstrating that the proposed changes involve no significant hazards consideration pursuant to 10 CFR 50.92 are included as Attachment B.
The proposed Technical Specifications contained herein represent chmges to Surveillance Requirements (SR) 4.6.5.1.c.1, drawdown time testing, and 4.6.5.1.c.2, inleakage testing, for SECONDARY CONTAINMENT INTEGRITY. An associated Bases change to Section 3/4.6.5, " Secondary Containment," is also provided. These changes are needed to resolve the secondary containment drawdown issue as discussed below.
NMPC discovered that SRs 4.6.5.1.c.1 and 4.6.5.1.c.2, for the Secondary Containment, did not provide adequate assurance that the radiological consequences from a design basis loss of coolant accident would remain within 10 CFR Part 100 guideline values and GDC 19 criteria. As an interim measure, NMPC implemented certain compensatory measures through administrative controls to ensure that the radiological consequences of such an accident would remain within the above regulatory criteria. These controls include maintaining an adequate differential between service water temperature and secondary containment temperature by deliberate heating of secondary containment and more restrictive limitations on the drawdown time and the inleakage limits than those currently in the Technical Specifications.
By letter dated June 1,1992, and during a meeting with the Staff on October 22,1992, Niagara Mohawk proposed to resolve the secondary containment drawdown issue by replacing the existing Standby Gas Treatment System (SGTS) with a new SGTS ofincreased capacity. Based on the complexities of the installation and operation of the new SGTS, p o r; A T 7 9405030269 940427
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s Page 2 NMPC has concluded that the planned replacement of the SGTS does not represent the best alternative from safety, operational and cost perspectives to resolve this issue. After careful consideration of the available alternatives and reviews of fission product behavior studies j
spanning a decade, NMPC has concluded that using the existing Standby Gas Treatment with i
a revised source term supporting a drawdown time of 40 minutes provides the best alternative.
Accordingly, Niagara Mohawk now proposes to revise the design basis radiological analysis j
and its source term to support an increase in the drawdown time by removing certain undue i
conservatisms related to the assumption of the immediate release of the source term specified in Regulatory Guide (R.G.) 1.3, " Assumptions Used for Evaluating the Potential Radiological Consequences of a Loss of Coolant Accident for Boiling Water Reactors." The revised source term is based on NRC-sponsored research from the past several years and will only be applied to the first 40 minutes after the accident. The R.G.1.3 source term will then be applitJ for the remaining duration of the accident. The revised source term
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continues to provide a conservative representation of the timing and release of radioactivity during the accident. The radiological evaluation for this accident, which reflects the revised source term and an assumed drawdown time of 40 minutes, demonstrates that doses remain below 10 CFR Part 100 and GDC 19 criteria. Although the radiological doses using the revised source term increase, they are still comparable to the doses presented in the Updated Safety Analysis Report using the R.G.1.3 source term.
l The proposed change to the drawdown time limit of SR 4.6.5.1.c.1 and the proposed change to the secondary containment inleakage limit of SR 4.6.5.1.c.2 have been established based on consideration of the revised source term. The proposed changes to these SRs establish the performance requirements of the Standby Gas Treatment System and the Secondary Containment to provide assurance that a secondary containment pressure of-0.25 inch water gauge with respect to the outside surrounding atmosphere will be established in less than 40 minutes following a Design Basis Loss of Coolant Accident. The proposed Technical Specification change and the use of a revised source term will allow a reduction in the required differential temperature between service water and secondary containment air from current values such that deliberate heating of secor.dary containment is no longer anticipated.
The proposed changes to the Surveillance Requirements and the revised source term will l
eliminate the potential for a plant shutdown due to excessive differential temperature requirements. The elimination of the deliberate heating of secondary containment will improve the service life of equipment within secondary containment, improve worker safety and performance, thereby reducing radiation exposure and the potential for human error.
Also, these changes avoid the safety implications and the significant economic hardship, i.e.,
approximately 15 million dollars, associated with the installation of a new Standby Gas Treatment System.
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Page 3 Niagara Mohawk Power Corporation is requesting this license amendment be issued as soon as possible to avoid excessive heating of the secondary containment during the summer of 1994 and beyond. Pursuant to 10 CFR 50.91 (b)(1), Niagara Mohawk has provided a copy of this license request and the associated analysis regarding no significant hazards consideration to the appropriate state representative.
Very truly yours,
[frdf b
B. Ralph Sylvia Exec. Vice President - Nuclear BRS/KWK/Imc Attachments xc:
Regional Administrator, Region I Mr, B. S. Norris, Senior Resident Inspector Mr. R. A. Capra, Director, Project Directorate I-1, NRR Mr. J. E. Menning, Project Manager, NRR Ms. Donna Ross Division of Policy Analysis and Planning New York State Energy Office Agency Building 2 Empire State Plaza Albany, NY 12223 Records Management
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