ML17059A348
| ML17059A348 | |
| Person / Time | |
|---|---|
| Site: | Nine Mile Point  |
| Issue date: | 07/01/1994 |
| From: | Terry C NIAGARA MOHAWK POWER CORP. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML17059A349 | List: |
| References | |
| NMP2L-1480, NUDOCS 9407120119 | |
| Download: ML17059A348 (6) | |
Text
~
t~v L
) 1vla q5 v i
~.
V Ml RA NIAGARAMOHAWKPOWCR CQRPORATIONI30I PLAINFIELDROAO. SYRACIIS
. N,Y.132>2ITE PHONE (3i
-'5I4 July 1, 1994 NMP2L 1480 U. S. Nuclear Regulatory Commission Attn: Document Control Desk
%'ashington, DC 20555 RE:
Nine Mile Point Unit 2 Docket No, 50-410 Gentlemen.'iagara Mohawk Power Corporation (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 'i'echnical Specifications as set forth in Appendix A to the above mentioned license.
Supporting information and an analyses demonstrating that the proposed changes involve no significant hazards consideration pursuant to 10 CFR S0.92 are included as Attachment B.
The proposed Technical Specifications contairied herein represent changes to Surveillance Requirements (SR) 4.6.5.1.c. 1, drawdown time testing, and 4,6.5.1.c.2, inleakage testing, for SECONDARY CONTAINMENTINTEGRITY. An associated Bases change to Section 3/4.6.5, "Secondary Containment,'s 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.l and 4.6,5.l.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 QDC 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 arid secondary containment temperature by deliberate heating of secondary containment and more restrictive limitations on the drawdown time and inleakage limits than those currently in the Technical Specifications.
By letter dated June 1, 1992, (NMP2L 1346) and during a meeting with the Staff on October 22, 1992, Niagara Mohawk proposed to resolve the secondary contahment drawdown issue by replacing the existing Standby Gas Treatment System (SGTS) with a new SOTS of increased capacity.
Based on thc complexities of the installation and operation of a new
\\
Page 2 SGTS, NMFC has concluded that thc planned replacement of the SOTS does not represent a
desirable alternative from safety, operational and cost perspectives to resolve this issue.
After careful consideration of the available alternatives, NMPC has concluded that the use of the existing SGTS with consideration of fission product scrubbing and retention in the suppression pool and additional mixing in secondary containment provides a basis for resolution of this issue, Accordingly, Niagara Mohawk now proposes to revise the design basis radiological analysis to support an increase in the drawdown time from 6 to 60 minutes by taking credit for fission product scrubbing and retention in the suppression pool.
The current design basis radiological analysis does not take credit for the pressure suppression pool as a fission product cleanup system as permitted in NUREQ-0800, Section 6.5.5, "Pressure Suppression Pool as a Pission Product Cleanup System." in addition, NMPC proposes to take credit for additional mhing of primary containmcnt and engineered safety feature systems leakage with
$0% of the secondary containment free air volume prior to the release of radioactivity to the environment.
In the revised analysis, mixing is assumed to occur at the onset of a Design Basis Loss of Coolant Accident as the primary containment and the Engineered Safety Feature systems leak into secondary containment.
The current analysis takes credit for mixing within secondary containment only after achieving a -0,25 inch water gauge pressure in secondary containment with respect to the outside surrounding atmosphere, The radiological evaluation for this accident, which reflects these changes and an assumed drawdown time of 60 minutes, demonstrates that the doses remain below 10 CPR Part 100 guideline values and GDC 19 criteria, The revised radiological doses are lower than the doses currently presented in the Vpdatcd Safety Analysis Report.
The proposed change to the drawdown time limitof SR 4.6.5,1.c,1 and the proposed change to the secondary containment inleakage limitof SR 4.6.5.1,c.2 have been established based on consideration of the pressure suppression pool as a fission product cleanup system and consideration of additional mixing in secondary containment; 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 prcssure of -0.25 inch water gauge with respect to the outside surrounding atmosphere willbe established in less than 60 minutes following a Design Basis Loss of Coolant Accident.
The proposed Tcchnical Spec%cation changes, Qssion product scrubbing and retention by the suppression pool and additional mixing in secondary containment willallow a reduction in the requirwi
- differential temperature between service water and secondary containment air from current values such that deliberate heating of secondary containment would no longer be anticipated.
The proposed changes to the Surveillance Requirements and the revised design basis radiological analysis willalso eliminate the potential for a plant shutdown due to excessive differenth1 temperature requirements.
The elimination of the deliberate heating of secondary containment willimprove the service Hfe of equipment within secondary containment,
Page 3 and improve worker safety aud 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 10 million dollars, associated with the instaHation of a new Standby Gas Treatment System, By letter dated April27, 1994 (NMP2L $468), Niagara Mohawk proposed an alternate approach to resolve the secondary containment drawdown issue using a revised source term, This alternate approach uses the same changes to the Technical Specifications and Bases centained in this latter.
JLfter dicouccias the April 97, lMA loner with the Staff, Niagara Mohawk requests that the Staff temporarily stop its review of the April 27, 1994 letter.
After approval of this proposed amcndmcnt, Niagara Mohawk willwithdraw thc April27, 1994 letter.
Niagara Mohawk Power Coryoration is requesting that the enclosed Application be giv~n a.
priority review to avoid exoessive heating of thc secondary containmcnt during the summer of 1994 and beyond.
Medmum hcatin> of secondary containment is expected to occur from late August to early September.
Pursuant to 10 CPR 50.91 (b}(l),Niagara Mohawk has provided a copy of this license amendment request and the associated analyses regarding no signi6cant hazards consideration to the appropriate state representative.
Very truly yours, BRS/KWK/Imc Attachments C. D. Terry Vice President - Nuclear Engineering xc:
Regional Administrator, Region l Mr. B. S. Norris, Senior Resident Inspector Mr. M. L. Boyle, Acting Director, Project Directorate I.1, NRR Mr. D. S. Srinkman, Senior 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