ML20245B346
| ML20245B346 | |
| Person / Time | |
|---|---|
| Site: | Oregon State University |
| Issue date: | 04/17/1989 |
| From: | Andrea Johnson Oregon State University, CORVALLIS, OR |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 8904260045 | |
| Download: ML20245B346 (6) | |
Text
,
x , .,
-]
. . r 3 Radiation Center We".
University Corvallis, Oregon 97331 . (soa 7n2m e J April 17,1989 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555
~
Reference:
Oregon State University TRIGA Reactor (OSTR),
License No. R-106, Docket No. 50-243
Subject:
Report filed in accordance with Section 6.7.b.2 of the OSTR Technical Specifications Gentlemen:
The following report is being submitted in accordance with Section 6.7.b.2 of the OSTR Technical Specifications. The report supplements information provided to the NRC's Region V office during an initial tele-phone contact with Mr. Emilio Garcia at approximately 3:30 p.m. on Thursday, April 6,1989, and during subsequent telephone conversations on April 7, 1989. The report deals with an event which occurred at the OSTR wherein it appears that pulse-mode operations were conducted in a manner which was contrary to the limiting condition of operation stated in section 3.5.2 of the OSTR Technical Specifications.
Background Infomation:
For approximately 20 years OSU has used an external high-speed recorder for gathering additional data about pulses, when such data were needed.
For example, the recorder has often been used during nuclear engineering
. laboratory classes. Attachment of the additional recorder has always been at console terminals provided by General Atomic Company specifically for such applications. These terminals (TP3 and TP4) are normally bridged by a jumper connector, and are shown along with the complete Nyt circuit in the attached diagram. .Since about mid-1987, the older high-speed re-corder has been replaced by a recorder system comprised of an amplifier and a computer-based data acquisition system (CDAS).
8904260045 890417 - kAA
{DR ADOCK0500g3 I l \
Oregon State University is an Affirmative Action / Equal Opportunity Employer
~
. . USNRC April 17,1989 Description of Event:
During the late morning of April 6,1989, the OSTR was being prepared for routine pulsing. Since this particular pulsing effort was to be in support of a routine nuclear engineering laboratory class, the instructor, a senior reactor operator, attached the CDAS to the Nyt circuit.
When the OSTR is switched to the pulse mode, the red pen on the console chart recorder, which normally records the log power, records the fuel temperature. Similarly, the blue pen, which normally records the linear power, records the peak power of the pulse via the Nyt circuit.
At about 11:38 a.m. on April 6 the reactor was pulsed with a $2.00 reactivity insertion and the blue pen went off-scale. It was quickly l
determined that the reason for this was the absence of a 100-ohm resistor, which is normally placed across console output terminals TP3 and TP4 when recorders are attached. This had the effect of changing the scaling of the voltage for the recorder and therefore caused the blue recorder pen to go off-scale. The pulse itself was entirely normal in all other re-spects. The fuel temperature measured by the red pen was 325 C, which is totally within the normal range for a $2.00 pulse. From previous fuel temperature records, the estimated actual peak power of the pulse was 1450 MW.
The cause of the problem was immediately corrected by attaching the required 100-ohm resistor across the console terminals, and the reactor was pulsed again at about noon. The second pulse used a $2.25 reactivity insertion in keeping with the laboratory class protocol. Following this pulse the blue pen went to 83.5% of full scale, which indicated a peak power of 3345 MW. It was immediately recognized that this was too large a value for a $2.25 pulse with an indicated fuel temperature of only 380 C.
The peak power should have been approximately 2260 MW based on the observed fuel temperature. An examination of the chart recorder showed t%at when the reactor was switched to pulse mode, just prior to the second pulse, the blue pen moved upscale to about 60% of a full scale reading. A number of recorder checks were then performed, without actually pulsing, in an attempt to determine the cause of this response.
As a result of the above situation, the Reactor Supervisor terminated the laboratory class, and all pulsing operations were halted. The Radiation Center Director, the Reactor Administrator, and the Chairman of the Reactor Operations Committee (ROC) were appraised of the situation and an investi-gation was immediately berun. The computerized recorder system was removed from terminals TP3 and TP4 and the normal jumper lead replaced. The reactor operations staff and the Scientific Instrument Technician then performed a check of the Nyt circuit. This is a standard electrical check of the Nyt cia uit which is performed semi-annually. The check showed that the Nyt circuit was fully operable and unaffected by the previous events.
Omission of the 100-ohm resistor during the first pulse apparently damaged the amplifier for the CDAS, such that it then charged the capacitor labelled C2 on the Nyt circuit diagram. This in turn caused the blue pen to move upscale and read high when switched to the pulse mode for the second pulse.
l .
1 .
"USNRC April 17,1989 I Following notification of Region V on the afternoon of April 6, and after further discussior . with Region V and Headquarters personnel on the morning of April 7, the full ROC was briefed on the event, its causes, corrective actions currently implemented and proposed, and on the nature of the discussions with the USNRC. The ROC suspended further use of ex-ternal recording devices during pulsing unless specifically approved by the Committee. The Committee also agreed to meet again to review and approve the written report being prepared for the NRC, and voted to allow the reactor to resume normal operations. Two pulses were then conducted to provide better estimates of the actual peak power levels obtained on April 6. The $2.00 j to 325 C on April 6) pulse
, and hadpower a peak a peak fuelMW of 1420 temperature of 327 Cfor(as opposed (1450 MW estimated !
the April 6 pulse). The $2.25 pulse had a fuel temperature of 376"C (380 C on April 6) and a power of 2220 MW (2260 MW estimated for April 6). During 1 the afternoon of Friday, April 7,1989, the Oregon Department of Energy (Mr. William Dixon) was also notified of the event and the results of the follow-up pulses.
l Corrective and Preventive Actions Currently Implemented:
- a. The computerized recording system (CDAS) has been disconnected from the console and will not be reconnected without ROC approval.
- b. The Senior Reactor Operator involved and the Reactor Supervisor have j i been reprimanded by the Director of the Radiation Center and the Reactor ;
Administrator during a special meeting to review the event. In addi- l tion, all operators have been admonished by the Director of the Radi- ;
ation Center to be vigilant with respect to Technical Specification i l requirements. An Operations Instruction Bulletin (01B) has also been issued emphasizing this matter.
- c. A special reactor operator requalification training session regarding
- the Teichnical Specifications has been scheduled for April 26, 1989.
l j d. OSTR administrative procedures have been amended to ensure that no l external measuring or recording device will be connected to reactor l measuring channels or safety channels without ROC approval of a 10 CFR 50.59 safety evaluation and any needed operating procedures.
However, it is not intended that ROC approval be required for normal use of standard diagnostic equipment by the Scientific Instrument Technician or a designated replacement,
- e. An additional amendment to the OSTR administrative procedures has been made stipulating that when classes are in the reactor control room, the operator of record will not be the instructor of the class.
This will minimize any potential distraction of the operator during class sessions.
- f. A further amendment to the OSTR administrative procedures has also been made stating that the Reactor Supervisor will personally check l
the connection of any external systems attached to reactor measuring channels or safety channels. This requirement is not intended to apply to the normal use of standard diagnostic equipment by the Scien-tific Instrument Technician or a designated replacement.
o .
USNRC April 17, 1989 Corrective and Preventive Action to be Completed by April 30, 1989:
Training and examination of licensed operators regarding requirements of the OSTR Technical Specifications will be completed by the above date.
A performance-based written exam will be given at the conclusion of the training session and all licensed operators must obtain a passing score of at least 70%. The training and examination will be administered by the Reactor Administrator, who will therefore be excused from taking the examination. (This is in keeping with normal OSTR operator requalification program procedures.) Copies of the completed examinations will be kept on file.
Corrective and Preventive Action to be Implemented Prior to Further Use of the Computerized Recording System:
The design of the computerized recording system will be carefully reexamined by the ROC in order to prevent a reoccurrence of the event beitig reported.
This may include permanently attaching a 100-ohm resistor across the TP3 and TP4 terminals, and will include whatever changes are needed to keep the CDAS amplifier from charging the Nvt capacitor.
Sunniary of Points Relating to the Event Being Reported:
- a. Upon recognition of a possible violation of the Technical Specifica-tions, all reactor operations were immediately discontinued. Reactor operations were not started again until after the event had been re-ported to the USNRC and restart-approval obtained from the OSTR Reactor Orarations Committee.
L. As soon as the initial investigation was completed, the event was reparted promptly and in a timely manner to the USNRC, Region V.
- c. The Technical Specification for pulse-mode operation (section 3.3) limits only the reactivity insertion for the purpose of ensuring that the fuel temperature safety limit will not be exceeded. As stated previously, both of the pulses were normal in terms of peak power and fuel temperature, and clearly neither of the pulse-mode limits (i.e., reactivity inserted and fuel temperature) were exceeded.
- d. There are no safety implications related to pulsing with the Nvt mea-suring channel inoperable. There is no Technical Specification limit on peak power from a pulse,
- f. An additional recorder for measuring pulse characteristics has been routinely attached to TP3 and TP4 for classes since the reactor began operation. The CDAS has been in use since 1987, and functions only as an additional recorder. Therefore, its use was not regarded as a facility change, test, or experiment requiring a safety analysis under 10 CFR 50.59.
j ,.
1 I . 4
( 'USNRC April 17,1989 i
( g. In our opinion, the OSTR policy for performance of 10 CFR 50.59 reviews (as detailed in the administrative operating procedures) is among the most strict and comprehensive ir use by any university research l reactor.
- h. The OSTR has been pulsed 1134 times since 1967 with no malfunctions or irregularities.
l 1. Corrective and preventive actions are being taken promptly to provide a high degree of assurance that this and similar events will not occur.
I Oregon State University's policy remains to be one of complete and open communication with the NRC and full cooperation with the Commission's regulatory program. We regret that this event occurred, and we do not take such situations lightly. We hope that you will find this report to be factually complete and responsive to the circumstances described.
Should you have questions after your review of this matter, please let me know. I wiil be pleased to provide whatever additional information you may need.
Yours sincerely, 1
A. G J hnson Direc r AGJ/ef/13-051 cc: Standardization and Non-Power Reactor Project Directorate, Division of Reactor Projects III, IV, V and Special Projects, Office of Nuclear Reactor Projects, Washington, DC 20555, Attn: Mr. Al Adams.
Regional Administrator, USNRC, Region V.
Oregon Department of Energy, Salem, Oregon, Attn: Mr. Harry Moomey.
Mr. T. V. Anderson, Reactor Supervisor, SRO.
Dr. S. E. Binney, Chairman, Reactor Operations Committee, SR0.
Dr. B. Dodd, Reactor Administrator, SR0 Mr. A. D. Hall, Reactor Operator.
Dr. J. F. Higginbotham, Senior Health Physicist, SRO.
!I\j'
_ 1 R E
. . D
_ R O
2 .
C E
I R E
C N
A" D E E"
P M*
I H"
NV G"
I M H M
4 O 5 RI a
, 2
- 3~
t i
u c
r i
C 2 2 V
% c0 N r 8 1
2 g
i F
I Rw9 C
3 4 _
K I
5 P P R2 T T .
=
O '-
r -
e p
S m P R M
A E
9 u M J A
R H i C C
I I
O
.