ML20044C757
| ML20044C757 | |
| Person / Time | |
|---|---|
| Site: | Framatome ANP Richland |
| Issue date: | 04/22/1993 |
| From: | Femreite B SIEMENS POWER CORP. (FORMERLY SIEMENS NUCLEAR POWER |
| To: | Martin J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| Shared Package | |
| ML19311B001 | List: |
| References | |
| CAL, NUDOCS 9305120184 | |
| Download: ML20044C757 (3) | |
Text
L.
_- ll April 22,1993 i
U.S. Nuclear Regulatory Commission Region V Attn: J. B. Martin, Regional Administrator 1450 Maria Lane Walnut Creek, CA 94596-5368 l
Subject:
Completion of Conversion Line-2 Powder Preparation Systems Moderator Intrusion Analysis : Response to February 12,1993, NRC Region V Confirmatory Action Letter
References:
(1)
Letter, J. B. Martin to B. N. Femreite,
- Confirmatory Action Letter, February 12,1993 (2)
NRC inspection Report No. 70-1257/93-02, March 10,1993
Dear Mr. Martin:
As part of its investigation of a February 7,1993, uranium powder spillinside a feed hopper hood, a Region V-directed Augmented inspection Team (AIT) developed a specific concem regarding the potential for moderator intrusion into the Conversion Line 2 uranium oxide blending and powder preparation system (powder preparation lines 2 and 3). Pursuant to this concern, Region V issued a Confirmatory Action Letter (Ref.1) which documented l
Siemens Power Corporation's (SPC's) agreement to " perform an engineering evaluation of the potential intrusion of moderating liquids into the uranium oxide blending and powder preparation system, and define the specific controls necessary to prevent criticality." The CAL also delineated alternate methods and controls by which SPC could conduct powder transfers into the powder preparation systems, pending completion of the assessment and resolution of NRC concerns.
l The engineering evaluation specified in the CAL has been completed (SPC Document No.
EMF-93-068(P)) and is attached for your information. The study, conducted by a team representing Manufacturing Engineering and Plant Operations, consisted of three parts: 1) definition / description of the system analyzed,2) identification of the different paths by which moderators could potentially enter the system, and 3) identification of existing controls already in place to protect the system from moderator intrusion via the identified paths. The information developed during the evaluation was utilized to assess whether existing controls were sufficient to preclude loss of moderation control via moderator intrusion into the system.g 1
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B.N. Femreite Siemens Power Corporation 1
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Page 2 April 22,1993 The evaluation concluded that adequate controls are presently in place to prevent a criticality from occurring in the blending and powder preparation equipment during routine operations.
These controls also provide a high degree of confidence that moderation control will be maintained in the Conversion Line 2 blending and powder preparation equipment even in the event of an accident which would deliver moderators to the vicinity of the powder preparation area. In evaluating two of the postulated accidents (steam pipe break and flooding from a service water pipe break), the prescribed immediate action by the operator to terminate l
powder transfer was not considered in calculating response times. Therefore these calculations ignored operator intervention and assumed that the Vac-U-Max
- system continued to operate, in order to establish a worst-case scenario for moderator intrusion in such quantities as to approach critical conditions.
I The evaluation did identify a number of improvements that will enhance the level of control under postulated accident conditions, thereby providing a greater degree of protection.
Three of these planned engineering changes provide automatic or remote shutdown i
capability of the vacuum transfer system, thus terminating moderator intrusion into the powder preparation equipment under accident conditions. The improvements are listed in Section 1.0, " Introduction / Summary" of the attached engineering evaluation report and are discussed more fully under Section 4.0," Recommendations".
t While SPC has determined that its existing controls sufficiently reduce the likelihood of moderator intrusion into the blending and powder preparation equipment, we have decided that a number of the enhancements will be completed prior to removing the interim control measures imposed by the CAL These items, which are expected to be completed by May 21,1993, are as follows:
Installation of Vac-U-Max
- shutdown switches in control rooms (Recommendation 1).
Installation of " deadman" switches on manually-operated vacuum wands (Recommendation 2),
Installation of moisture (humidity) detectors in powder prep hoods with l
automatic vacuum system shutdown (Recommendation 3),
Upgrading of Accurate
- feeder hopper covers with spring-activated closures and insta!!ation of lights inside the feeder hoppers (Recommendation 6), and installation of covers on vacuum system air inlets (Recommendation 7).
Two additional modifications identified in the analysis will require further engineering analysis / design work and will be completed within approximately four months. These enhancements involve modifications to the steam supply system (Recommendation 4) and relocation of Vac-U-Max
- pick-up heads and installation of a false floor in the powder feeder i
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Page 3 April 22,1993 hood (Recommendation 5). All modifications will be performed in accordance with our Engineering Change Notice Procedure (EMF-858, No.1.13).
j Although not specifically a part of the subject analysis, SPC has given further consideration to i
the status of the powder feeder limit switches involved in the February 7,1993 powder spill.
i We have determined that the level of criticality safety will be enhanced by designating these devices as being part of the criticality safety controls. Accordingly, the powder feeder limit switches will be incorporated into the applicable criticality safety analysis (CSA) and proper l
function of the switches will be checked periodically under the Instrument Repetitive Maintenance (IRM) system. Inclusion of the switches into the CSA and IRM system will be completed prior to lifting the interim control measures imposed by the CAL.
If you require further information, please contact L J. Maas at (509) 375-8537.
Very truly yours, f
/
.N. Fe rpite Plant Mariager BNF:pm l
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