ML20211G129
| ML20211G129 | |
| Person / Time | |
|---|---|
| Site: | 07001113 |
| Issue date: | 09/30/1997 |
| From: | Reda R GENERAL ELECTRIC CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9710020060 | |
| Download: ML20211G129 (5) | |
Text
g GE Nuclear Energy
,v m en n r o + x a mn, m 6 N 6 KUD September 30,1997 U. S. Nuclear Regulatory Commission Do:ument Control Desk Washington, DC 20555-0001
Subject:
30-Day Report of Event - Discharge of Uranium to llF Processing Ft cility in Excess of Safety-Basis Analysis
Reference:
(1) NRC License SNM-1097, Docket # 70-1113 l
(2) NRC Regalation 10 CFR 70.50 (3) NRC Bulletin 91-01 In accordance with 10 CFR 70.50(c)(2), GE Nuclear Energy hereby submits the required written report for a Leptember 4,1997 event involving a transfer of uranium from the Dry Conversion Process (DCP) facility to the HF processing facility. This event was reported by telephone on September 5,1997, by Mr. L.E. Paulson to the NRC Operations Center in accordance with 10 CFR 70.50 and Bulletin 91-01.
On September 4,1997, at approximately 2:25 p.m., traces of uranium were confirmed to be present in the stack sample of the HF recovery facility. This off-normal situation was declared an unusual (off-normal) event per internal GE procedures at 2:40 p.m.
Operations involving DCP conversion and HF recovery were immediately suspended, and a team was chartered to investigate the root-cause of this event.
The event was reported within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> pursuant to 10 CFR 70.50(b)(2) wh'ich requires reports when safety systems fail to respond as anticipated. In this case, it appeared that the small quantity of uranium discharged to the HF facility was more than our safety-basis documentation allowed. In addition, some of the material had been transferred to unfavorable geometry vessels, thus GE subsequently modified the report to acknowledge that NRC Bulletin 91-01 also applied to this event. All reports were made within the required 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> period.
dh
.f There were no injuries or detectable exposure to workers or to the public. Air samples at
/g I the site boundaries indicated no detectable activity above background. This event did not )
result in the release of uranium above regulatory limits but did exceed internal GE action l
[
levels.
l 9710020060 970930
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PDR ADOCK 07001113 C
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Document Control Desk
. September 30,1997 -
Page 2 The investigation results, along with corrective actions are summarized in Attachment 1.
4 If additional information is needed regarding the event, I can be contacted at (910) 675-5889.
Sincerely, GE Nuclear Energy i2 Q
Ralph J. Reda Attachment cc:
RJR-97-122 LA Reyes - NRC Region 11 Administrator MF Weber - NRC, NMSS CJ Monetta CP Kipp
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Document Control Desk -
September 30,1997-Page1of3 ATTACHMENT 1 Location of the Event:
Hydrofluoric Acid (HF) Recovery Facility
- GE Nuclear Energy Production,' Wilmington, NC Date and Time of the Event:
September 4,1997, at approximately 2:25 p.m.
Isotones. Ouantities. Chemical and Physical Form:
2 Uranium enriched to 2% in "U as UO F fine particulate -
22 22.9 grams (31.54 microcuries) uranium released. The quarterly limit is 1,250 microcuries, therefore, the quantity is significantly below regulatory limits.
Approximately 200 grams U enriched to 2% in "U released to unfavorable 2
geometry wash column and dilute storage tank in IF recovery facility. The safe batch is 15.9 kilograms U at 5% U235 enriclunent.
Individual Radiation Exposures:
An assessment was made of the additional dose at the property line due to the release with the standard assumptions. Utilizing the COMPLY code (Clean Air Act Modeling for Radionuclide Emissions), the effective dose equivalent from this small release of uranium was calculated to be 0.052 mrem. The highest on-site ambient air sampling result for an 8-day period (includinphe release) resulted in 0.0035 mrem for an on site receptor. As compared to the off site annual dose limit of 25 mrem (based upon compliance with NRC 10 CFR 20, Subpart D and EPA 40 CFR 290 regulations for off-site dose requirements to the maximally exposed individual) this release is considered insignificant. Also, the
- 0.052 mrem is significantly lower than the 10 mrem / year NRC standard 10 CFR 20.1101(d) and EPA 40 CFR 61 regulations.
Descrintion of Event:
At approximately 1425 hours0.0165 days <br />0.396 hours <br />0.00236 weeks <br />5.422125e-4 months <br /> on September 4,1997 a small release of uranium from the Dry Conversion Process (DCP) to the HF recovery process facility was detected _via normal sampling.
Document Control Desk
(
September 30,1997 Page 2 0f 3 The cause of the release was associated with restart activities of DCP Line #1.
Line #1 was down due a plug in the UF. feed nozzle to the conversion kiln. The system kiln had been disassembled, and the plugged nozzle was removed and replaced with a new one. The system was reassembled, and start-up sequencing was begun on 9/3/97 at around 1730 hours0.02 days <br />0.481 hours <br />0.00286 weeks <br />6.58265e-4 months <br />.
Our investigation has detennined that during attempts to unplug the nozzle with nitrogen, a small amount (less than 300 grams) of UF. became trapped in the nitrogen lines. Several attempts had been made to clear the nozzle using nitrogen flows, however, this was not effective in removing the plug, and the Line #1 conversion process was shutdown on 8/29/97. During the unplugging attempts, the UF entered the nitrogen and pressure detector lines as a vapor, and as the system cooled, it solidified on the walls of the lines. During the restart sequence on 9/3/97, the system was preheated and the nitrogen purges were initiated. Since the process steam was not introduced to the syst,;m, there was no water to react I
with the UF., and so it remained as an un-reacted vapor. The nitrogen, in effect, acted as an inert carrier gas and transported some of the trapped UF from the nitrogen lines to the HF facility. The investigation detennined that approximately 73% of the uranium was retained in the HF facility by the liF condenser and washing column. The remaining uranium (approximately 23 grams) was discharged from the washing column through the exhaust stack. The investigation team concluded that the condenser in the HF facility failed to trap the UF., as was assumed in the safety analysis.
Corrective Actions Taken:
Additiona'. active engineered controls (AECs) were added to interlock UF. block valves with hydrolysis and pyrohydrolysis steam valves.
Functional tests were developed and conducted to verify functionally of UF6/ steam flow interlocks, The maximum delivery of uranium upon total loss of steam based on control system e
response was calculated. The maximum credible holdup value of UF. in the conversion kiln and associated piping that could be released un-reacted to the HF facility was determined and analyzed for criticality, radiological and environmental
- impacts, A license amendment to SNM-1097 was submitted to NRC for changes to control e
parameters in HF acid recovery area.
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Document Control Desk September 30,1997 Page 3 of 3 Stack sampling frequency was increased from 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> to 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> during restart e
phase.
Updated safety-basis documentation (Integrated Safety Analyses, Technical Reports, e
Criticality Safety Analyses, and Operating Procedures) to reflect the addition of active engineered controls and maximum credible holdup of UF, in the conversion kiln and associated piping that could be released un. reacted to the 11F facility.
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