ML19344E534
| ML19344E534 | |
| Person / Time | |
|---|---|
| Site: | Hatch  |
| Issue date: | 08/19/1980 |
| From: | Widner W GEORGIA POWER CO. |
| To: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| IEB-80-17, NUDOCS 8009020180 | |
| Download: ML19344E534 (2) | |
Text
p N,$.ZsD""'
r w o w e,.asas
,a tm u G n a r302
% i ; " _ 4 ?4 R2 (Q6n
.C fl E G _, h w _ wm August 19, 1980 GeorgiaPower UN r,. vg ]4 2l Pl: 08 <r - r ,xr - r-U. S. Nuclear Regulatory Commission Office of Inspection and Enforcement
REFERENCE:
Region II - Suite 3100 -QP0 - 101 Marietta Str a, NW 50-321/50-3fN Atlanta, Georgia 30303 I&E Bulletin 80-17 ATTENTION: Mr. James P. O'Reilly Gentlemen: Your letter of July 18, 1980, transmitted Supplement 1 to I&E Bulletin 80-17. Item B.1 of the Supplement requires that a system to continuously monitor wa'er levels in all scram discharge volumes be installed by all licensees by September 1, 1980. A written description of the system design was to be provided. Georgia Power Company believes this request is appropriate for those plants with scram switches which are separated from the scram discharge volume by relatively long runs of small diameter piping which create the potential for loop seals or flow blockage. However, not all BWRs are configured in such a fashion. In particular, Hatch, Brunswick and Duane Arnold units all have instrumented volumes which are imediately adjacent to and below the scram discharge volumes (SDV), and which communicate with the SDV via piping as large as the SDV or larger. The instrumentation in these volumes provides a direct indication of the presence or absence of water in the SDV. These devices provide a scram function with indication in the control room. Due to this design feature, we believe the existing design for our facility already meets the requirement for a continuous monitoring of water level in the scram discharge volumes. The questions of redundancy and diversity of the SDV instrumentation are being considered by other ongoing programs. However, until these generic questions are resolved, we believe the existing system will provide a highly reliable means of detecting the presence of water in the SDVs. We have augmented the high reliability of the existing instrumentation by requiring that a functional test be performed on each scram switch and flor; assembly by the addition of water to physically verify operability following each scram above and beyond the requirements stated in the Tech Specs. It is our position that even if a float should fail fcllowing a scram, it has provided its intended function by reliably indicating the presence or absence of water in the SDV prior to the scram, and the failure will be immediately detected by the functional test procedure. We have previously stated that we are procuring a UT system for installa-tion. We believe this system will provide Georgia Power Company with additional information on the proper functioning of the float switches assemblies and will aid in the engineering effort which will address the criteria to come out of resolution of the ongoing generic programs. We remain convinced of the adequacy of our existing instrumentation and are installing this temporary UT system for our information. W M G AI, p., 4 8 009 0 2 0 /fD'
- 1 GeorgiaPower d U. S. Nuclear Regulatory Commission Office of Inspection and Enforcement August 19, 1980 Page Two Item B.2 of Supplement i requested a study of potential vent design modi-fications. We have evaluated the vent system with regard to its ability to reet the design objectives for the system and have concluded that the system provides a more than adequate vent. We are continuing to evaluate the role, if any, of vent configuration in the float failures which occurred. A reroute of the vent line from the instruments back to the SDV, rather than to the vent header, is being 'evluated. The time required for this modification, should we decide to modify the system, would not be an appreciable factor. However, it has yet to be demonstrated that the vent design was a contributing factor in the float failure event. The cause of the float failures is being investigated. However, as stated above, the actions we have taken in the interim, until a cause has been detemined and any necessary modifications made, adequately assure that the float switches will perform their intended functions.
Very truly yours, ? f ' {/ f ( f k... & W. A. Widner RDB/mb xc: Director of the Office of Inspection and Enforcement Director of the Division of Operating Reactors, Office of Nuclear Reactor Regulation -}}