IR 05000458/1986036
| ML20213D891 | |
| Person / Time | |
|---|---|
| Site: | River Bend  |
| Issue date: | 10/29/1986 |
| From: | Chamberlain D, Jaudon J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | |
| Shared Package | |
| ML20213D885 | List: |
| References | |
| 50-458-86-36, NUDOCS 8611120328 | |
| Download: ML20213D891 (4) | |
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APPENDIX U.S. NUCLEAR REGULATORY COMMISSION
REGION IV
NRC Inspection Report:
50-458/86-36 '
License:
NPF-47 Docket:
50-458 Licensee:
Gulf States Utilities (GSU)
P. O. Box 220 St. Francisville, Louisiana 70775 Facility Name:
River Bend Station (RBS)
Inspection At:
River Bend Station, St. Francisville, LA Inspection Conducted:
October 16-23, 1986 Inspector:
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D. Dj Chamberlain, Senior Resident Inspector Date Approved:
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/C M M J. L J@ don, Chief, Proje.ct Section A Date
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O ReactorlProjects Branch
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Inspection Summary Inspection Conducted October 16-23, 1986 (Report 50-458/86-36)
Area Inspected:
This was a special unannounced inspection conducted to review the conditions and actions resulting from a potential unreviewed safety question.
Results: Within the area inspected, one potential violation was identified (failure to conduct an adequate review for determination of whether or not a modification involved an unreviewed safety question).
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DETAILS 1.
Persons Contacted.
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Principal Licensee Employees -
- J. E. Booker, Manager, River B' nd Oversight'.
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- J. L. Burton, Supervisor, Independent Safetyf Engineering Group (ISEG)'
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- W. J. Cahill, Jr., Senior Vice President, River Bend Nuclear Group-
- J. C. Deddens,-Vice President,-River Bend Nuclear Group
- R.-G. Finkenaur, Electrical Engineer
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.D. R. Gipson, Assistant Plant Manager, Operations
- E. R. Grant, Director, Nuclear Licensing-
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- J.-R. Hamilton, Director, Design Engineering
- R.'W. Helmick, Director, Projects
- G. K. Henry, Supervisor, ' Electrical Engineering
- G. R. Kimmell, Supervisor, Operations Quality Assurance (QA)-
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- R. J. King, Supervisor, Nuclear Licensing
- J. F. Mead, Senior Engineer, ISEG
- M. F. Sankovich, Manager, Engineering
- R. B. Stafford, Director, Operations QA
- K. E. Suhrke, Manager, Projects
- 0..Williamson, Supervisor, Operations The NRC senior resident inspector (SRI)'also interviewed additional licensee personnel during the inspection period.
- Denotes those persons that attended the exit interview conducted on October'24, 1986.
2.
Control Building Ventilation System Modification This inspection was conducted by the SRI to review the potential unreviewed safety question identified by the licensee staff.resulting from a temporary modification of the control building' ventilation system and to review the plar,aed corrective actions.
On.0ctober 16, 1986, the SRI was notified by the licensee that a previous modification to the plant had been implemented based on a potentially inadequate unreviewed safety question determination.
The modification involved a change to the control building ventilation system to prevent spurious tripping of the control building chillers and chilled water pumps from a low ventilation air flow signal by bypassing the low' air flow trip.
This modification was made by
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temporary alteration number 85-HVK-026 on October!29,1985,' for chilled.
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water pumps "A" & "B" and by prompt modification request (PMR) number 86-0038 on June. 27,:1986,- for chilled water pumps "C" and'"D".- The required.
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unreviewed safety question determinations performed in both instances
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failed to recognize that.the modification prevented the automatic starting of the redundant division of control building ventilation;under certain
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single failure scenarios..The licensee apparently discover;ed this~
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condition during the required design process of converting the1rompt ~
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modification request to a modification request.
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- ThA control building ventilation system is designed to main'ta'in certain _
environmental conditions in the vital switchgear rooms, chiller; rooms,'and main control room under normal and accident conditions'for equipment.
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protection and for control room habitability.
In the. original plant '
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design, as described in FSAR section 9.2.10.5, a low air flow through any control building air handling unit or a trip of both' chilled water compressors would trip the associated chilled water-pump. This would
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cause a _ low water flow condition which would automatically start the other division of control building ventilation. The control building environment safety analyses thereby assumes automatic operation of this system following a loss of coolant (LOCA) event with or without offsite power available and with a single failure in the control building ventilation system. However, as stated previously, the installed modification would have prevented the automatic starting of the redundant division of control building ventilation under certain single failure scenarios. Therefore, the control building ventilation system would not be operational for area temperature control without manual operator action under certain conditions. The automatic initiation of the charcoal filtration portion of the control building ventilation system for radiation exposure protection of control room operators was apparently not affected by the modification. The plant safety analyses apparently assumes no manual operator action for the first 20 minutes of any accident scenario.
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The installed modification to the control building ventilation system l
apparently involves 'an unreviewed safety question as defined by 10 CFR
Part 50.59 in that the modification increased the probability of occurrence and the consequences of malfunction of equipment important to i
safety as previously evaluated in the safety analysis report. Regulation i
10 CFR Part 50.59 requires prior Commission approval of any modification j
which involves an unreviewed' safety question. The licensee installed the identified modification to the control building ventilation system on October 29, 1985, without obtaining prior Comission approval. This failure to obtain prior Commission approval of a change to the facility which involved an unreviewed safety question was identified by the SRI as
an apparent violation (458/8636-01).
i The licensee is continuing the investigation of the root cause of this i
condition and the following immediate corrective actions have been completed and/or initiated:
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'Immediately removed the system modifications on October 16, 1986.
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Initiated a review of other plant modifications for problems with the
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unreviewed safety question determinations.
Verified that plant alarm response procedures would require plant
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operators to start the redundant division of control building ventilation when the running division tripped.
. Initiated a review of the design process procedures and controls
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which allowed the apparent inadequate unreviewed safety question determination.
Initiated a safety evaluation of the consequences of no control
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building ventilation system operation for the first 20 minutes of an event during the time that the modifications were installed.
Initiated a review of the facility review committee (FRC) role in
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approval of unreviewed safety question determinations.
The SRI will continue to monitor licensee actions in this area.
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3.
Exit and Inspection Interview An exit interview was conducted on October 24, 1986, with licensee representatives identified in paragraph 1.
During this interview, the SRI reviewed the scope and findings of the inspection.
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