ML20090F655
| ML20090F655 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 07/17/1984 |
| From: | Mills L TENNESSEE VALLEY AUTHORITY |
| To: | Adensam E Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8407230181 | |
| Download: ML20090F655 (2) | |
Text
F TENNESSEE VALLEY AUTHORITY
)
CH ATTANOOGA, TENNESSEE 374ot 400 Chestnut Street Tower II July 17,1984 Director of Nuclear Reactor Regulation Attention:
Ms. E. Adensam, Chief Licensing Branch No. 4 Division of Licensing U.S. Nuclear Regulatory Commission Washington, D.C.
20555
Dear Ms. Adensam:
In the Matter of
)
Docket Nos.
50-327 Tennessee Valley Authority
)
50-328 We request an exemption to the reporting requirements of 10 CFR 50.72(b)(2)ii and 10 CFR 50.73(a)(2)(iv) for spurious Containment Building ventilation,,
Auxiliary Building ventilation, and Control Room ventilation isolations. This request is being submitted in accordance with the requirements of 10 CFR 50.12 and 10 CFR 50.73(f). The enclosure provides the justification for the proposed exemption request.
If you have any questions concerning this matter, please get in touch with Jerry Wills at FTS 858-2683 Very truly yours, TENNESSEE VALLEY AUTHORITY L. M. Mills, nager Nuclear Licensing d efore me Sworn p subscr 1984 day of this Notary Public gg My Commission Expire 3 /"c/ ~ 7 Enclosure cc:
U.S. Nuclear Regulatory Commission (Enclosure)
Region II Attn:
Mr. James P. O'Reilly Administrator 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323 0407230181 840717 DR ADOCK 05000 fl 1983-TVA 50TH ANNIVERSARY An Equal Opportunity Employer
ENCLOSURE JUSTIFICATION FOR THE REQUEST FOR AN EXEMPTION TO THE REPORTING REQUIREMENTS OF 10 CFR 50.72(b)(2)(ii) AND SO CFR 50.73(a)(2)(iv)
There have been a large number of telephone $ealls and licensee event reports (LER) to NRC regarding spurious and inadvertent Containment Building ventila-tion isolations (CVI), Auxiliary Building ventilation isolations (ABI), and Control Room ventilation isolations (CRI) since-the beginning of the year.
These are due to the new reporting requirements in 10 CFR 50.72(b)(2)(ii) and 10 CFR 50.73(a)(2) (iv) which states, "Any event er condition that results in manual or automatic actuation of any engineered safety feature (ESF).
" is required to be called in to the NRC within four hours and sjbmit an LER within 30 days.
These ventilation isolations have been caused by spurious signals on radiation monitors wnich were caused by a combination of vibration and electromagnetic interference (EMI) problems. Bouncing and arcing of relay and switch contacts, alarm buzzer, timers, microswitches, and heliarc welding are known sources of EMI that can cause a monitor to spike.
Inadvertent actuations can also be attributed to the movement of radwaste past a monitor or otherwise artifically raising the background radiation enough to cause a spurious isolation.
Recent corrective actions show a substantial reduction in isolations due to spurious spikes. These reductions can be attributed to one monitor setpoint being raised, flow switches being mounted on rubber mounts, revised instructions, better communications between personnel, and other EMI protection.
We are evaluating the following long-term actions to reduce or eliminate these spurious isolations.
1.
Assessment of the availability of a flow switch with sufficient deadband to reduce chattering at low ficy.
2.
Addition of a time delay to the actuation signal to allow spike decay time.
3 Addition of a filter for the AC cables to the monitors.
4.
Implementation of a time delay of CVI.
5.
Modification of CVI flow alarm circuit from AC power to DC power.
6.
Feasibility of interlock of CVI with purge air and vent dampers to inhibit CVI when the dampers are closed.
Some or all of these actions will be implemented as appropriate.
There have been 14 LERs written to date to report 44 incidents regarding spurious or inadvertent ESF actutions.
Reporting of future events of this nature to the NRC will not provide additional information or benefit. In fac t,
- his reporting results in key plant personnel spending unproductivc time preparing repetitive reports. We therefore request an exemption to the reporting requirements for spurious and inadvertent containment ventilation isolations, Auxiliary Building ventilation isolations, and Control Room ventilation isolations. We will continue to examine all ESF actuations in accordance with the requirements of 10 CFR 50.73 to determine the root cause but request' approval (exemption) to not report those ESF actuations that are determined to be spurious or inadvertent. We believe that the exemption request is justified.
t
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