ML20244C421
| ML20244C421 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 04/12/1989 |
| From: | Black S Office of Nuclear Reactor Regulation |
| To: | Kingsley O TENNESSEE VALLEY AUTHORITY |
| References | |
| GL-88-17, TAC-69865, TAC-69866, NUDOCS 8904200202 | |
| Download: ML20244C421 (4) | |
Text
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. April 12, 1989 Docket Nos. 50-327/328 Mr. Oliver D'. Kingsley, Jr.
Senior Vice President, Nuclear Power Tennessee Valley Authority 6N 38A Lookout Place 1101 Market Street Chattanooga, Tennessee 37402-2801
Dear Mr. Kingsley:
SUBJECT:
COMMENTS ON THE TENNESSEE VALLEY AUTHORITY RESPONSE TO GENERIC LETTER 88-17 FOR EXPEDITIOUS ACTIONS FOR LOSS OF DECAY HEAT REMOVAL (TAC NOS. 69865 AND 69866) - SEQU0YAH NUCLEAR PLANT, UNITS 1 AND 2 Generic Letter (GL) 88-17 was issued on October 17, 1988 to address the potential loss of decay heat removal (DHR) during nonpower operation.
In the GL, we requested (1) a description of your efforts to implement the eight recommended expeditious actions of the GL and (2) a description of the enhancements, specific plans and a schedule for implementation of the six recommended program enhancements.
The NRC staff has reviewed your response to GL 88-17 on expeditious actions in the letters of January 6 and 25, 1989. We find that it meets the intent of the GL but lacks some of the details requested in Enclosure 2 of GL 88-17.
The staff guidance and position information pertaining to the expeditious actions are given as eight items in Section 2.0 of Enclosure 2 to the GL.
For a number of the items, you indicate that development and evaluation is still required. You may wish to consider several observations in order to assure yourselves that the actions are adequately addressed.
1.
You mention training including a discussion of the Diablo Canyon event with operations personnel of your staff before entry into the next reduced inventory condition. However, you do not specify the outline of the subjects that would be covered except to refer to the GL.
2.
You do not state what pressure relieving pathways would be used in the reactor coolant system (RCS) and what specific time you would commit for containment closure as specified in Enclosure 2 of the GL. Also, you have not provided your method for quick closure of the equipment hatch and discussed the ability of the hatch to meet the closure criteria.
3.
As previously discussed with you by phone conference call on December 9, 1988 and January 3 and 17, 1989, we agree that because of the " inverted top hat" style of upper reactor internals and the potential for degrading the sealing system between the reactor vessel and its head, an exception f)(
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to the containment closure requirements when the reactor vessel head is being reinstalled after_ refueling is acceptable. This will allow Sequoyah to substitute a five foot value below the reactor vessel flange instead of three foot for the implementation of administrative controls for containment closure.
You have stated that the other recommendations in the GL regarding independent level instrumentation and additional coolant injection will be met any time the RCS water level is three feet below the reactor vessel flange.
4.
Your addressing of containment closure is cursory and no information is I
provided regarding how you will keep track of and control the many potential openings which may have to be closed simultaneously.
Your procedures and administrative controls should address this topic.
5.
You indicate that water level in the reactor vessel while in a reduced inventory condition will be continuously provided in the main control room (MCR)byatleasttwodifferentinstrumentsforwideandnarrow range levels.
For wide range, one train of the reactor vessel level indication system (RVLIS) will be used for the primary wide range level monitoring loop.
If this train is not available, a temporary, wide-range transmitter tapped off the RVLIS hot leg sense line of the other train that is vented to containment atmosphere will be used. You also stated that independent, wide-range monitoring will be provided by a hard-piped sight glass.
The sight glass will be tapped off a crossover leg and be vented to containment atmosphere.
If the sight glass were to become inoperable, a tygon hose will be aligned to the same crossover tap.
You stated that narrow-range level indication will be provided by a temporary differential pressure transmitter that is tapped off the RVLIS hot leg sense line and vented to containment atmosphere.
Independent, narrow-range indication will be provided by the same hard-piped sight glass that is used for redundant wide-range level indication and will be displayed in the MCR by a camera arrangement.
When two instruments are in place, care should be taken to resolve any discrepancy between the two measurement systems. Also, the pressure of the reference leg should approximate the pressure of the void in the hot leg or be compensated to obtain the correct level value. When using
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common taps, care must be taken tn ensure accuracy as independence is lost.
l You have stated that readings for the above systems will be monitored in the MCR but do not mention the use of alarms as stated in the GL.
Since the level readings are monitored in the MCR, the need for frequent logging only arises for the case of loss of DHR.
Your presentation is vague on whether the tygon hose readings will be included in the display in the MCR by a camera arrangement.
l 6.
Walking the tygon tube following installation to verify lack of kinks or i
loop seals is necessary.
Experience shows that periodic walkdowns are i
I needed after installation. We recommend daily walkdowns when the tygon tube is in use, with an additional walkdown immediately prior to its being placed in use. Your training for affected personnel should address this.
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o Mr. Oliver D. Kingsley, Jr. April.12, 1989 7.
You indicate that gravity feed from the refueling water storage tank (RWST) is a possible source for makeup to the RCS.
You have not stated any opening to relieve pressure. The removal of a pressurizer manway or steam generator manway is a means to provide RCS venting. We note that relatively large hot side openings in the RCS, such as a pressurizer manway, can still lead to a pressure of several psi. The large steam flow in combination with flow restrictions in the surge line and lower pressurizer hardware may lead to pressurization. Calculations should be performed to verify the effectiveness of the opening.
There is no need to respond to the above observations.
As you are aware, the expeditious actions you have briefly described are an interim measure to achieve an immediate reduction in risk associated with reduced inventory operation and these will be supplemented and in some cases replaced by programmed enhancements. We intend to audit both your response to the expeditious actions and your programmed enhancement program. The areas l
where we do not fully understand your responses, as indicated above, may be covered in the audit of expeditious actions.
This closes out the staff review of your responses to the expeditious actions listed in the GL. The area of programmed enhancements will be addressed in a separate letter.
l Sincerely, Original signed by Suzanne Black. Assistant Director for Projects TVA Projects Division Office of Nuclear Reactor Regulation cc: See next page Distribution Docket File H. Balukjian NRC PDR W. Hodges Local PDR A. Marinos Projects Reading J. Brady ADSP Reading K. Jenison D. Crutchfield B. Grimes B. D. Liaw E. Jordan S. Black ACRS (10)
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Mr. Oliver D. Kingsley, Jr. '
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General Counsel Regional Administrator, Region II Tennessee Valley Authority U.S. Nuclear Regulatory Comission 400 West Summit Hill Drive 101 Marietta Street, N.W.
Eli B33 Atlanta, Georgia 30323 Knoxville, Tennessee 37902 Resident Inspector /Sequoyah NP Mr. R. L. Gridley c/o U.S. Nuclear Regulatory Commission Tennessee Valley Authority 2600 Igou Ferry Road SN 1578 Lookout Place Soddy Daisy, Tennessee 37379-Chattanooga, Tennessee 37402-2801 Mr. John T. LaPoint Mr. Michael H. Mobley, Director Tennessee Valley Authority Division of Radiological Health Sequoyah Nuclear Plant T.E.R.R.A. Building, 6th Floor P.O. Box 2000 150 9th Avenue North Soddy Daisy, Tennessee 37379 Nashville, Tennessee 37219-5C4 Mr. M. Burzynski Dr.. Henry Myers, Science Advisor Tennessee Valley Authority Committee on Interior Sequoyah Nuclear Plant and Insular Affairs P.O. Box 2000 U.S. House of Representatives Soddy Daisy, Tennessee 37379 Washington, D.C.
20515 Mr. D.
L., Williams Tennessee Valley Authority Tennessee Valley Authority Rockville Office 400 West Sumit Hill Drive 11921 Rockville Pike WIO 885 Suite 402 Knoxville, Tennessee 37902 Rockville, Maryland 20852 County Judge Hamilton County Courthouse Chattanooga. Tennessee 37402 i
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