ML20058E221
| ML20058E221 | |
| Person / Time | |
|---|---|
| Site: | Framatome ANP Richland |
| Issue date: | 11/12/1993 |
| From: | Femreite B SIEMENS CORP. |
| To: | Faulkenberry B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| Shared Package | |
| ML20058E224 | List: |
| References | |
| CAL, NUDOCS 9312060215 | |
| Download: ML20058E221 (4) | |
Text
'
..y.
""$Feo
~
Ribbon
? N0Y15 gggy,0, j
l l
l November 12,1993 l
l U.S. Nuclear Regulatory Commission l
Region V Attn:
B. H. Faulkenberry Regional Administrator 1450 Maria Lane Walnut Creek, CA 94596-5368 Response to July 17,1992 Confirmatory Action Letter Regarding Occurrence of Free Moisture in Large Lot Blender l
References:
1.
Confirmatory Action Letter, J.B. Martin (NRC Region V Administrator) to Siemens Nuclear Power Corporation, July 17,1992 2.
EMF-1505, Revision 2, " Occurrence of Free Moisture in the 63-Cubic Foot Day Mixer, Nov. 8,1993.
Dear Mr. Faulkenberry:
l On July 16,1992, Siemens Power Corporation - Nuclear Division (SPC) notified NRC of the discovery of what appeared to be excessive moisture in the off-gas filter housing of a 63-cubic foot capacity UO2 Powder blender. The blender, installation of which had been completed in June,1992, was being operated on a limited basis under engineering control to perform a series of qualification test runs. The discovery was made during the pre-inventory cleanout of the system in preparation for the annual SPC inventory. The presence and quantity of a hydrogenous material within the confines of the blender are significant, since criticality safety of the system is, in part, based on strict control of hydrogen (moderation control) within the unit and its contents. The unanticipated presence of condensed moisture within the confines of the unit was viewed as a condition for which the severity and remedy were not readily determined. Time constraints related to reporting under NRC Criticality Safety Bulletin 91-01 did not allow for a fullinvestigation of the source and magnitude of the moisture and therefore SPC proceeded with the conservative approach of NRC notification under Bulletin 91-01.1 i
1 The Bulletin 91-01 report was subsequently retracted (at NRC-HQ suggestion) when i
subsequent in-depth investigation by SPC revealed that the occurrence did not involve the loss of a controlled parameter or create a condition outside the bounds of the applicable criticality safety analysis.
B.N. Femreite Siemens Power Corporation Nut! ear Dmsion Eng;neenng and Manufactanng Facility p
P: art! a.g' d gki Rchla r=;
2101 Hom Rapids Road. PO Box 130. Rchiand, WA 99352 0130 Tel (509) 375-8191 Fat (509; 375 B402 9312060215 931112 U
PDR ADOCK 07001257 U
i C
l Page 2 November 12,1993 On July 17,1992, NRC Region V, after consultation with staff from NRC-HQ, issued a Confirmatory Action Letter (CAL) restricting further operation of the blender until certain conditions had been met (Ref.1). By this letter, SPC is conveying to NRC the actions that have been taken to address the conditions imposed by the CAL Further planned actions i
that will also be completed prior to operation of the blender are outlined as well. Each of the CAL requirements is presented below along with a discussion of SPC disposition of the requirement.
l 1
1.
"An evaluation of the source of water in the off-cas line and the potential effect on criticality analysis for the blender will be completed."
This incident was formally investigated by an SPC incident investigation Board (llB).
The 118 provided a full documentation of the event, an evaluation of probable causes, and recommendations for corrective actions. Included is a recommendation to " assure that all actions called for in the NRC Confirmatory Action Letter are taken before the l
megablender will be operated."
I A specific evaluation of the source of observed moisture in the blender was conducted by SPC Process Engineering. The engineering evaluation confirms the initial finding of the 11B which concluded that the observed moisture was present in the incoming uranium oxide powder (which was well within moisture control limits). The moisture was released from the powder by heating related to powder oxidation, and subsequently condensed on the cooler surfaces of the blender. A copy of that evaluation (EMF-1505, Revision 2) is attached (Ref. 2).
An evaluation of the potential effect of this phenomenon on the criticality safety analysis for the large lot blender has been conducted by the Criticality Safety l
Component. The possibility of this phenomenon occurring had been discussed in the original criticality safety analysis for the blender and the limits on the moisture content of the powder in the blender were established with this phenomenon in mind.
Although the observed moisture emanated from blended powder lots that were well within moisture specifications, condensation of free moisture in this equipment is unacceptable from a criticality control standpoint. Process Engineering has identified engineering and procedural modifications that are expected to prevent this type of i
occurrence (see 2., below). Subsequent to approval by an SPC startup council, the blender will be returned to operation under engineering control for a series of tests during which the equipment and operating parameters will be optimized to prevent moisture condensation. This program of testing under engineering control will be covered by a criticality safety analysis (CSA) which willimpose limits on UO moisture 2
content and UO mass allowed in the blender. Based on the information obtained 2
during the testing period, the Criticality Safety Component will revise the large lot l
blender CSA to inecrporate finalized equipment and procedural parameters.
Finalization of this CSA will be required prior to a startup council release of the large lot blender to routine plant operation.
l i
Page 3 November 12,1993 2.
T.any deficiencies are identified. appropriate corrective actions will be taken."
Although the evaluations discussed in 1, above, revealed that the phenomenon observed was bounded by the existing criticality safety analysis, the condensation of moisture in moderation - controlled equipment is not acceptable from an operational l
or safety standpoint. To address this phenomenon, the following corrective actions l
have been identified:
installation of nitrogen sweep gas lines for the removal of moisture l
l during the blending and blender download stages, installation of a moisture detection / shut-off system on the incoming
=
nitrogen header, revision of the standard operating procedure for blender operation to require periodic cycling of the blender auger to transfer warm powder to the outside of the blend as well as to require periodic inspection of the blender interior, and completion of a test program to optimize sweep gas flows and auger operation.
l L
Completion of these corrective actions (in progress) will provide a means to mitigate consequences of the moisture release / migration as well as to determine optimal blender operating conditions to minimize the potential for this phenomenon to occur.
3.
"A basis for continued operation of the blender will be developed."
SPC proposes the following as the bases for safe startup and operation of the large lot blender:
a)
All identified engineering / equipment modifications will be completed.
b)
All required changes to criticality safety documentation will be completed.
c)
All revisions to standard operating procedures will be finalized and followup training of operators completed.
d)
A formal SPC startup council will be convened to review effective completion of a) - c), above, and to determine the need for any other
]
pre-startup actions. When the startup council is satisfied that all pre-startup actions have been effectively completed, approval will be given i
to operate the blender under engineering control.
e)
While under engineering control, a series of full-scale blending tests will be conducted to test the efficacy of the equipment and procedural I
modifications. Based on the results of this testing and evaluation, further changes will be made if necessary to optimize blender operating conditions with respect to criticality safety.
f)
The startup council will be reconvened to re-evaluate whether all recommendations and required modifications have been completed, including any identified during the operations under engineering control.
This would include issuance of a final CSA that incorhorates all
Page 4 November 12,1993 pertinent equipment and operating parameters. When satisfied that this has occurred, the council will approve the transition from engineering control to routine plant operation.
i 4.
- items 1 and 3 above will be submitted to the NRC for review and aareement."
See SPC responses to items 1 and 3, above.
5, 7he blender will not be operated until NRC has completed the review of the evaluation and aarees with the basis for continued operation."
The large lot blender has not been operated in any mode (production or testing) since the moisture condition was reported on July 16,1992. SPC will await formal notification from NRC that the CAL has been lifted prior to operation of the large lot blender.
SPC believes that the above actions will provide for the safe operation of the large lot blender and are responsive to the requirements imposed by the CAL We appreciate your review of our response. SPC is working to a schedule that will allow initial startup of the blender under engineering controlin January 1994. If you have questions or need additionalinformation, please contact LJ. Maas on 509-375-8537.
Very truly yours,
",, a
'l
'jj i
0p$
B. N. Femreite Plant Manager 1
i I
i I