ML12128A428

Response to Texas A&M University - Request for Additional Information Regarding the Texas A&M University AGN-201M Reactor License Renewal Application (TAC No. ME1588).

ML12128A428
Person / Time
Site:	Texas A&M University
Issue date:	04/12/2012
From:	Hassan Y Texas A&M Univ
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
TAC ME1588
Download: ML12128A428 (3)

Text

DWIGHT LOOK COLLEGE OF ENGINEERING Department of Nuclear Engineering

-UTXS &

April 12, 2012 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555-0001 Docket No.50-059

SUBJECT:

Response to "Texas A&M University - Request For Additional Information Regarding the Texas A&M University AGN-201M Reactor License Renewal Application (TAC NO. ME1588)"

In response to the RAI dated July 25, 2011, the following questions are being submitted for review: 8,9,10, and 13.

If you have any questions, please do not hesitate to contact me at: (979) 845-4161, or e-mail at v-hassan@tamu.edu.

I declare under penalty of perjury that the foregoing is true and correct. Executed on April 12, 2012.

Sincerely, Yassi- Hrassan, Ph.D.

Interim Department Head Encl. (1) 337 Zachry Engineering Center.

3133 .TAMU College Station,TX 77843-3133 Tel. 979.845.4161 Fax. 979.845.6443 Gac nuclear.tamu.edu 0M

Texas A&M University AGN-201M License No. R-23 Docket No.50-059 Responses to Request for Additional Information Questions 8,9,10, and 13

8. The design change for the Channel #2 period function replaces two mechanical relays with a an optoisolator and solid state relay. The Keithley 4103 electronic trip and Potter and Brumfield relay KHS17D1 1 were replaced with solid state components. The new scram circuit is designed with an NTE3086 optoisolator and 74HC73 dual JK flip-flop with reset.

The NTE3086 optoisolator exhibits a saturated turn-on time of 5[ts and a saturated turn-off time of 25 hs. The 74HC73 chip has a typical propagation delay of 16ns with a maximum value of 41 ns. These response times are significantly faster than the previously installed equipment. The Keithley 4103 electronic trip is designed to have a response time of lOims.

The typical operating time of relay KHS I 7D 11 is 13ms with a typical release time of 6ms.

Given the large improvement in response time of the solid state components, there is no negative impact on safety margin.

9. The design change for the Channel #3 scram circuit replaces two mechanical relays with a an optoisolator and solid state relay. The Keithley 4103 electronic trip and Potter and Brumfield relay KHS 17D 11 were replaced with solid state components. The new scram circuit is designed with an NTE3086 optoisolator and 74HC73 dual JK flip-flop with reset.

The NTE3086 optoisolator exhibits a saturated turn-on time of 5[ts and a saturated turn-off time of 25ps. The 74HC73 chip has a typical propagation delay of 16ns with a maximum value of 4 lns. These response times are significantly faster than the previously installed equipment. The Keithley 4103 electronic trip is designed to have a response time of lOims.

The typical operating time of relay KHS 17D 11 is 13ms with a typical release time of 6ms.

Given the large improvement in response time of the solid state components, there is no negative impact on safety margin.

10. Solid state relays have replaced the relay circuits in the Channel #3 high power and low power trips, Channel #2 high power and low power trips, period trip, earthquake scram, and low reactor tank temperature trip. Replacing these relays did not have a negative impact on the circuit response time because the solid state relays that replaced the previous relay circuits are significantly faster. Channel #2 and #3 were previously discussed in other questions. The remaining trips two were equipped with KHP l7D 1I relays. The typical operation time of this relay is 25ms. These relay circuits were replaced with the same solid state circuit comprised of an NTE3086 optoisolator and 74HC73 chip. The NTE3086

optoisolator exhibits a saturated turn-on time of 5ps and a saturated turn-off time of 25pts.

The 74HC73 chip has a typical propagation delay of 16ns with a maximum value of 41 ns.

13. In the event that the computer becomes unresponsive to the reactor control system by "freezing", the watchdog circuit will reboot the computer if a new data packet is not

.received every 0.05 sec. When the computer is reset, the loss of indication of Ch. #2 and

1. 3 to the scram bus will initiate a protective action. This watchdog scram ensures that the computer is operational during reactor operations. This scram does not have any impact on the safety analysis in SAR Chapter 13 because this scram is the same as a loss of signal to any safety channel.

This scram is initiated if new data packets are not received every 0.05 sec. or if the AGN computer control program is quit with the console power energized.

Proposed LCO Add T.S. 3.2.k 3.2.k The watchdog timer shall be installed during reactor operations Proposed Surveillance requirement Add T.S. 4.2.i 4.2.i The watchdog timer shall be tested annually.