ML20217D938
| ML20217D938 | |
| Person / Time | |
|---|---|
| Site: | Portsmouth Gaseous Diffusion Plant |
| Issue date: | 04/17/1998 |
| From: | Toelle S UNITED STATES ENRICHMENT CORP. (USEC) |
| To: | Paperiello C NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM), NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| References | |
| GDP-98-0085, GDP-98-85, TAC-L32045, NUDOCS 9804270143 | |
| Download: ML20217D938 (6) | |
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A Global Energy Company April 17,1998 GDP 98-0085 i
Dr. Carl J. Paperiello Director, Office of Nuclear Material Safety and Safeguards Attention: Document Control Desk U.S. Nuclear Regulatory Commission Washington, D.C. 20555-0001 Portsmouth Gaseous Diffusion Plant (PORTS)
Docket No. 70-7002 Response to Request for AdditionalInformation i
Certificate Amendment Request -TSR 2.1.3.11, Autoclave Smoke Detection System
Dear Dr. Paperiello:
The purpose of this letter is to provide a response to the NRC's request (TAC No. L32045) for additional information on the Certificate Amendment Request (CAR) regarding Technical Safety Requirement (TSR) 2.1.3.11, involving the minimum number of autoclave area smoke detector alarm circuits required to be operable. The request for additional information was provided to USEC in Reference 1 and identified additional information required by NRC to allow final action to be taken on the subject CAR. provides USEC's response to the request for additional infonnation. As specified in Enclosure I to this letter, USEC's evaluation regarding the minimum number of autoclave area smoke detector alarm circuits concludes that a single detector head above each respective autoclave that is operable is sufficient, under anticipated operating conditions, to provide warning of a significant UF release. Nevertheless, to address NRC's concem as described in Reference 1 and clarified in a discussion between E. Wagner (USEC) and Y. Faraz (NRC) on April 14, 1998, regarding the possibility of extreme wind conditions in the X-343 building affecting the ability of a single UF detector above an operable autoclave to detect a release, USEC will submit a revision 6
to proposed TSR 2.1.3.11 to include a Condition in the Limiting Condition for Operation (LCO)
Action statement that addresses situations where there are fewer than four (4) smoke detectors (total) l operable in X-343. This requirement will supplement the proposed requirement in the June 30,1997
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CAR that at least one detector (of the four required) shall be operable above any operable autoclave in X-343. The revision to TSR 2.1.3.11 will be submitted to the NRC by May 30,1998. M%
9804270143 980417 PDR ADOCK 07007002 C
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6903 Rockledge Drive. Bethesda. MD 20817-1818
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Dr. Carl J. Paperiello April 17,1998 GDP 98-0085, Page 2 Any questions regarding this matter should be directed to Mr. Mark Smith at (301) 564-3244.
Commitments contained in this submittal are identified in Enclosure 2.
Sincerely,
/1 S. R. IJ Steven A. Toelle Nuclear Regulatory Assurance and Policy Manager
Enclosures:
1.
Response to Request for Additional Information, Portsmouth Certificate Amendment Request - Minimum Number of Autoclave Area Smoke Detector Alarm Circuits Required to be Operable (TAC No. L32045).
2.
Commitments Contained in this Submittal cc: Mr. Robert C. Pierson, NRC l
NRC Region III Office NRC Resident Inspector-PORTS NRC Resident Inspector - PGDP Mr. Randall M. DeVault, DOE I
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Dr. Carl J. Paperiello April 17,1998 GDP 98-0085, Page 3 REFERENCES 1.
Letter from Robert Pierson (NRC) to James H. Miller (USEC), Portsmouth Certificate Amendment Request - Minimum Number of Autoclave Area Smoke Detector Alarm Circuits Required to be Operable - Request for Additional Information (TAC No. L32045), March 19, 1998.
2.
Letter from Steven A. Toelle (USEC) to Dr. Carl J. Paperiello (NRC), Certificate Amendment Request - TSR Section 2.1.3.11 - Autoclave Smoke Detection System, USEC Letter GDP 97-0128, July 30,1997.
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O GDP 98-0085 Page 1 of 2 United States Enrichment Corporation (USEC)
Response to Request for AdditionalInformation (TAC L32045)
Request:
This (Request for Additional Information) involves the potential influence that convective wind currents may have on a UF6 release inside an autoclave facility, especially with the building side doors and/or crane hatches open. Please describe the negative effect, if any, a high atmospheric wind speed would have on the timely detection and alarm for a UF release inside the autoclave facility 6
in the presence of these building openings. This concern applies more to X-343 and to a lesser extent to X-342 and X-344, where a significant cross ventilation could occur under these conditions.
Specifically, please provide a basis as to why the minimum operability requirements of a single detector head in one of two circuits covering an autoclave in X-343 under these conditions provides appropriate detection coverage.
Response
In the autoclave facilities (X-342A, X-343, and X-344) the UF smoke detectors are located near the 6
ceilings over the autoclaves. These detectors provide an alarm function only and are placed to provide the greatest sensitivity to a significant release (approx 8 lbs/sec) from a feed line/ pigtail failure outside of the autoclave. Other accident scenarios would have multiple alarms from the autoclave and/or would be caused by personnel error in lifting or connecting / disconnecting pigtails; in such cases, the detection of the release would be immediate and would typically not rely on the smoke detection system. In the case of such a release from a passive failure of the feed line or a pigtail, the smoke detectors would provide an alarm alerting the operating personnel to put the autoclaves into contairunent.
The X-342A and X-344 facility doors are located at a sufficient distance and orientation, relative to the autoclaves and smoke detectors, such that any outside wind (air currents) would not substantially affect the movement of a release and its reaction products up to the smoke detectors.
The X-343 Building has a somewhat different ventilation pattern. There are large rollup doors on the north and south ends of the building providing a vehicle path along the west side of the high bay.
The autoclave feed line and connection manifolds are along the east side of the high bay within a few feet of the building wall. The ventilation fans are mounted on the roof and provide air changes (approximately) every four minutes during the summer and very little air change during the winter.
The airflow from the ventilators combined with the upward velocity of UF release gases would, 6
under anticipated operational conditions, provide assurance that a single detector above the respective autoclave would detect the release even with the crane doors open. The main rollup doors are separated by a significant distance from the autoclave manifold area and would not significantly affect the air flow from the postulated release area.
O GDP 98-0085 Page 2 of 2 However, in the absence of test data, if significant winds were experienced (e.g. estimated to be approximately 25 mph or greater), the wind direction was directly north or south (the orientation of the X-343 building), and the crane doors were open, it is not possible to provide absolute assurance that a single detector located at either end of the X-343 building would not be adversely affected by these conditions. Significant airflow into the building from the crane doors would tend to move a release to the next detectors inside the building.
While the X-343 proposed TSR could potentially allow operation of one autoclave with only one smoke detector operable, this would be a very unlikely operating circumstance. Plant operations require multiple autoclaves to provide adequate feed. Additionally, the smoke detector circuits are not deactivated based on the number of operable autoclaves; rather, the operability of the smoke detectors determines operability constraints on the autoclaves. As such, it would be an extremely unlikely occurrence that there would ever be an occasion when only one smoke detector was operable; the likelihood of that condition occurring at a time when a significant wind velocity (e.g.
25 mph or greater) directly north or south into the X-343 building (0.18% at 10m height) is so remote as to be noncredible. It is therefore reasonable to conclude that the operational and physical configuration of the autoclave operations assures that adequate detectors would be operable to detect a release for those accident scenarios where they would be needed.
Nevertheless, to address NRC's concern as described in Reference 1 and clarified in a discussion l
between E. Wagner (USEC) and Y. Faraz (NRC) on April 14,1998, regarding the possibility of l
extreme wind conditions in the X-343 building affecting the ability of a single UF. detector above l
an operable autoclave to detect a release, USEC will submit a revision to proposed TSR 2.13 11 to j
include a Condition in the Limiting Condition for Operation (LCO) Action statement that addresses l
situations where there are fewer than four (4) smoke detectors (total) operable in X-343. This requirement will supplement the proposed requirement in the June 30,1997 CAR that at least one detector (of the four required) shall be operable above any operable autoclave in X-343.
i GDP 98-0085 Page1of1 i
Commitments Contained in this Submittal l
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USEC will submit a revision to proposed TSR 2.1.3.11 to include a Condition in the Limiting Condition for Operation (LCO) Action statement that addresses situations where there are fewer than four (4) smoke detectors (total) operable in X-343. This requirement will supplement the proposed requirement in the June 30,1997 CAR that at least one detector (of the four required) shall be operable above any operable autoclave in X-343. The revision to TSR 2.1.3.11 will be submitted to the NRC by May 30,1998.
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