ML20128G108
| ML20128G108 | |
| Person / Time | |
|---|---|
| Site: | University of Texas at Austin |
| Issue date: | 01/25/1993 |
| From: | Bauer T, Wehring B TEXAS, UNIV. OF, AUSTIN, TX |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML20128G112 | List: |
| References | |
| NUDOCS 9302120154 | |
| Download: ML20128G108 (4) | |
Text
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4 ^y DEPARTMEN's OF MECHANICAL ENGINEERING
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THE UNIVERSITY OF TEXAS AT AUSTIN
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Nudear Enginaring % hing lavrabry 10100 Burnet %d' Amtin, Tew 78738
($12)4'l-57H7 = FAX (512)471-4589 January 25, 1993 Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555
Subject:
Notification of Reportable Occurrence Docket 50-602
Dear Sir:
Pursuant to License R-129 Technical Specification I
- 6. 6. 2.2 (b) other events and 6.5.2 the following notification is provided. Discovery of the event during testing the week of January 19-22, 1993, was reported to the licensee's project manager, Al Adams, by telephone on January 25, 1993. Amendment of Technical Specification 3.2.2 is requested pursuant to 10CFR 50.56 to correct the condition.
The University of Texas (UT)- has identified a reportable event as part of a routine test and review of the ICS reactor
, system operation. The event is a change of the number of standard control rods subject to the simultaneous withdrawal interlock requirements when the reactor is in modes other than manual mode.
The event which occura during automatic or equare wave mode operation removes the regulating rod from the interlock recuirements. The Technical Specification 3.? .2 (c) states that 4 interlocks, one for each rod, are applicable for manual operation. By note to the table (page 14) the same requirement is applied to the automatic and square wave modes, however, the regulating rod in these modes is not part of the interlock cequence, thus reducing the applicable interlocks from 4 to 3.
The reportable event is'an error in the licensee's representation of the Technical Specifications. Review of the section 6 (page 6-12) of the Safety Analysis Report indicates n potential source of the error by way of a statement in the list of interlocks (item F). Item (F) applies to an inter'ock against manual operation of the regulating rod while ehat rod is in auto or square wave mode. This condition. however, does allow simultaneous movement of another rod other than the regulating rod. A review of the control software and startup program demonstrates that the condition (4 interlocks in auto mode or square wave mode) was not true at the initial test nor in subsequent or current control software configurations.
Discovery of the reportable condition occurred during test of an update replacement of the control system software. The software replacement corrected a wi*hdrawal interlock failure found by another licensee that compromised the withdrawal interlock logic. The corrected interlock ;rror was related to a mode switch change while the rod up awitch was depressed. The 1
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manufacturer,-.-General Atomics, has corrected the software-andi -
provided the: update version to UT; Review of this-software' -
correction was underway when-the present condition was-
- recognized. . . The-- reportable event iin this case - (UT)- is ~ ani
- erroneous Technical Specification and not'an. actual ~ event-related to the-instrument; control and-safety system.-
Corrective-action by the licensee is amendment of the Technical Specifications. No safety to reactor operation is; presented by the event. The~ amendment 1to the Technical Specifications is enclosed.
The licensee considers the loss of the interlock in automatic and square wave modes an acceptable safety; condition'..
Any withdrawal of a rod simultaneous with a mode (automatic or square wave) control condition that is moving-the' regulating rod up will automatically cause a change in the-regulating rods motion with both period and power-level constraints. These <
responses are tested in the_startup and checkout-procedures and are reevaluated periodically as part of software-updates and ,
replacements.
The licensee will refrain from use of the automatic and square wave modes until amendment of the Technical: ~
Specifications-is approved.
-Sincerely, gQ 7 b#
Thomas L. Bauer Assistant Director /NETL Approval: beMOd. bJbUb ,;
Bernard W. Wehring,= director /NETL-TLB:jgr Attachments: SAR page.6 - 12 Technical' Specifications pago'14 Technical Specifications _page 14 amendment 1/93 xc: U.S. NRC Region.IV R.LCharbeneau H. Woodson-(D. .Klein)
K. Diller
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UNITED STATES OF ~ AMEni'CA NUCLEAR REGULATORY COMMISSION l
I In the Matter of %
-The University of Texas 4 at Austin % Docket No. 50-602 Balcones Research Center %
Nuclear Engineering Teaching (
Laboratory (NETL) {
AFFID7 NIT Gerhard J. Fonken being duly sworn, hereby deposes and says that he is Executive Vice President and Provost, The University of Texas at Austin; t.n a t he is duly authorized to sign and file with the Nuclear Regulatory Commission the. - enclosed requested- Technical. Specifications amendement of.
license R-129, for docket 50-602; that he is familiar with the content thereof; and that the matters set forth therein are true and correct to the best of his knowledge and belief.
f Gerhhrd J. Fonken Executive Vice President and Provost Subscribed and sworn to b9 Qre me, a Notary Public in and for the State of Texas, this 49S day of (kLftuaAu.- , 19 Q.
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- @fARY PUBLIC in and for ttfe State of Texas s
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SAR 5/91 .
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.The manual and automatic reactor control modes are used for reactor operation from source level to 100% poier. These two modes are ,
used for manual reactor stcrtup, change in power level, and steady state ope ra t ion.' _The pulse mode generates high power levels for'very short periods of time, iligh-power snd low-power pulse- mode: options. are available. The square-wave operation allows the power level -to be raised quickly to a desired power level.
Manual rod control is accomplished by the lighted push buttons on '
the rod control panel. The top row of annunciators, when illuminated, indicates. magnet contact with the armature _ and magnet cvrrent.
Depressing any one of the AIR MAGNET push buttons _ vill interrupt the current to that magnet and extinguish the magnet current on indication.
If the rod is above the down limit, the rod will fall back into the core and the AIR-MAGNET light will remain extinguished _ until' the magnet is driven to the down limit where it again contacts the armature.
The middle row of pushbuttons (UP) .and the botto.n row' (DOWN) ' are -
used to position the control rods. Depressing the pushbuttons causes the control rod to move in the direction indicated. Several interlocks prevent the movement of the rods in the un direction under conditions such as the following:
- a. Scrams not roset.
- b. Magnet not coupled to armature.
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- c. Source level below minimum count.
- d. Two UP switches depressed at the same time,
- e. Mode switch in one of the pulse positions.
- f. Mode switch in AUTO poition (regulating rod only).
- . There is no interlock id Ibititg the-down direction of--the control rods except in the. case of the regulating rod while in the AUTO mode.
Automatic (servo) power control can be obtained by switching from manual . operation. to _ automatic operation. . All the instrumentation,-
safety, and interlock circuitry described above applies and is - in operation in this mode. However, the regulating rod is_now controlled
- - automatically _ in response to a power level and period _ signal. The y reactor - power level is compared with the L demand --level . set . by the operator.and is used to bring the reactor' power-to_the demand-level-on a
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fixed preset period. Logic _ for the automatic control operation by proportional and integral control is contained witn the digitalf i algorithms of the control system. -The purpose of this feature is ' to automatically: raintain the preset power level during long-term power i runs. _The fu- tion of automatic _ control: is provided by the regulating- ;
rod with a stepping motor drive. i I
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