ML20207J032

Ro:On 861211,actuation of Evacuation Alarm & Evacuation Alarm/Core Vent Sys Interlocks Occurred While Stack Count Rate Approx 300 Cps,In Potential Violation of Tech Specs. Cause Not Given.Vent Will Be Secured at 10 Cps During Drill

ML20207J032
Person / Time
Site:	05000083
Issue date:	12/19/1986
From:	Vernetson W FLORIDA, UNIV. OF, GAINESVILLE, FL
To:	Grace J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
References
NUDOCS 8701080259
Download: ML20207J032 (3)

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"'"'*^'*""a" NUCLEAR FACluTIES DIVISION C.G. VE RNE TSON, RE ACTOR MAN AGER NUCLEAR REACTOR BUILDING UNIVERSITY OF FLORDA '. ,'

GAlhESVILLE, FLORIDA 32611 , ,

- # sere PH0ht (904) 392-1429 TELEX 56330 g g$ b I3 December 19, 1986 Nuclear Regulatory Comm on Suite 2900 101 Marietta Street, N.W.

Atlanta, CA 30323 Atten tion: J. Nelson Grace Regional Administrator, Region II Re: University of Florida Training Reactor (UFTR)

Facility License R-56; Docket No. 50-83 Gentlemen:

On December 12, 1986 following discovery of the problem outlined in the scena-rio section below, Mr. Larry Meller of Region II was contacted and given a verbal description of events. In general, Mr. Meller agreed with the staff evaluation including the determination that the event is a potential violation of our Technical Specifications and hence a prormtly reportable event as spe-cified in the reporting requirement of paragraph 6.6.2(3) of the UFTR Techni-cal Specifications. Mr. Meller recommended that '"all evaluations be performed as for a technical specification violation. Therefore, this report is being transmitted to meet the tech spec requirement for a final report closing out the occurrence.

SCENARIO At 1037 hours0.012 days <br />0.288 hours <br />0.00171 weeks <br />3.945785e-4 months <br /> on Thursday,11 December 1986, the stack dilute fan and the core vent fan were secured by actuation of the evacuation alarm and the evacuation alarrvcore vent system interlocks while the stack count rate was approximately 300 cps. The count rate was due to a normal Argon-41 vent and stack inventory buildup established by a prior run starting at 0923 and secured at 101t (100 kWth operation from 0956 to 1016).

The automatic evacuation occurred as part of the Quarterly Evacuation Drill, (Surveillance Q-3) for which the scenario involved two area radiation monitors indicating radiation levels greater than the high level trip setpoint (10 mrem /hr). Establishment of the two area monitors at the high level trip set-point initiated the core vent / diluting fan interlock with the evacuation alarm as required by Technical Specifications. However, UFTR Technical Specifica-tions, Section 3.4.3, s ta tes:

3.4.3 Reactor Vent System The reactor vent system shall be operated at all times dur-ing reactor operation. In addition, the vent system shall be operated until the stack monitor indicates less than 10 counts per second (cps). Whenever the reactor vent sys tem is opera ting, air drawn through the reac tor vent sys tem shall be continuously monitored for gross concentration of radioactive gases. The output of the monitor shall be indi-cated and recorded in the control room. The reactor vent system shall be immediately secured upon detection of: a failure in the monitoring system, a failure of the absolute i filter, or an unanticipated high stack count rate. \ 0 8701080259 861219 ' * " " * * " ' ' " * " ' " " ' * * " " "

I PDR ADOCK 05000083 ,,CEm S p]qD

Nuclear Regulatory Commission December 19, 1986 Page Two EVALUATION Subsequent discussions of the event when discovered in the af ternoon (~1500 hours) indicated that the high count rate with the core vent system secured could constitute a violation of Technical Specifications. In assessing the consequences of a potential violation of Technical Specifications, the impact of the action on the premise or the bases of the Limiting Condition for Opera-tion (LCO) must be considered. This LCO is unusual in two respects.

First, there is no indication of the bases for the LCO. Disetasions with the UFTR Staff indicate that the LCO is based on the potential ter activated Argon gas exfiltrating into static atmosphere of the UFTR cell as well as buildup of radon from natural causes within the cell. A review of the recorder charts for the Air Particulate Detector (also alarmed for this drill scenario) and for the Area Radiation Monitors traced during the conduct of the drill shows no effect upon radiological conditions of the UFTR.

The second unusual aspect of this LCO is that the required condition does not relate to operating the reactor, but is a requirement imposed during a shut-down condition. As such, violation of this LCO may not be a reportable occur-rence as the reactor is not operating. This LCO also appears to be in conflict with the requirements that the evacuation alarm automatically secure the core vent system, and that the core vent system be secured on a loss of stack moni-tor or failure of the core vent absolute filter.

CONSEQUENCES Argon-41 production cannot be increased through this action of securing the vent system, and the effluent concentration for the duration of this event ac-tually had to decrease as the core vent damper closure that occurs with secur-ing the core vent fan stops air flow from the reactor. The fact that no nega-tive impact to radiological or reactor systems could or did occur from this event supports the evaluation that this event posed no potential for compro-mising reactor safety or the health and safety of the public.

These evaluations were reviewed individually with members of the Executive Committee of the Reactor Safety Review Subcommittee (RSRS) on December 12, 1986 prior to contacting Mr. Meller and then again in a formal meeting of the Executive Committee of the RSRS on December 12, 1986.

CORRECTIVE ACTION / RECOMMENDATION Since this event represents a potential violation of Technical Specifications, the RSRS recommended that this event be reported to the NRC as was done on December 12 and finalized with this report. Corrective action for the specific problem of securing the vent at >10 cps on the stack monitor during a drill will be assured by requiring that all drills be conducted prior to running the UFTR at power levels above 500 watts on the day of the drill and/or assuring the stack monitor is reading below 10 cps prior to drill initiation with a checkoff on the drill scenario card which will be added to Standard operating

l Nuclear Regulatory Commission December 19, 1986 Page Three Procedure O.5 as an additional part of the Q-3 drill form. This corrective action will be implemented prior to the next quarterly radiological emergency drill due in March, 1987.

The RSRS at its regular meeting on December 19 required a proposed Tech Spec change to be developed on the requirement for core vent system operation with stack monitor count rate above 10 cps; af ter re-evaluation and with support on a technical basis, Section 3.4.3 will be modified so that the requirement for not securing the reactor vent system above 10 cps can be modified, perhaps with only a recommendation that it not be secured above 10 cps. This change will be based upon the lack of safety and/or radiological effects from secur-ing the reactor vent system for short periods of time or even with a higher s tack count rate. This tech spec change will eliminate the conflict involved in securing the vent fan system for an actual emergency following a reactor run should such occur; this work will be completed by May 30, 1987; a subse-quent request for a' tech spec change will then be submitted.

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FINAL NOTE The RSRS Executive Committee members were contacted on December 12, 1986 rela-tive to the securing of the reactor vent system. The members of the RSRS Exe-cutive Committee all agreed that the incident had no impact on reactor safety or the health and safety of the public. Therefore, the UFTR was granted per-mission to commence normal operations as of December 12, 1986. A formal meet-ing of the Executive Committee was convened to document this permission.

As a further note, the full RSRS met at its regularly scheduled meeting on De- i cember 19, 1986 and unanimously supported the additional check on the drill scenario card and the proposed change in the tech specs required as corrective action by the RSRS Executive Committee and the UFTR staff and included in this report.

With this report this incident is considered closed with corrective action to be implemented as noted above.

Since rciy h $V ,

W W i

William G. Vernetson Director of Nuclear Facilities WGV/ps cc: Reactor Safety Review Subcommittee P.M. Whaley, Acting Reactor Manager