ML20206Q348
| ML20206Q348 | |
| Person / Time | |
|---|---|
| Issue date: | 07/04/1998 |
| From: | Callan L NRC OFFICE OF THE EXECUTIVE DIRECTOR FOR OPERATIONS (EDO) |
| To: | Burrows F NRC (Affiliation Not Assigned) |
| Shared Package | |
| ML20206Q280 | List: |
| References | |
| NUDOCS 9905190107 | |
| Download: ML20206Q348 (1) | |
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Brian Sheron - 2 I
protection channels that use dynamic components (e.g., Over temperature Delta T (OTA Overpower Delta-T (OPAT) and low pressuriher pressure). For each channel credited in the safety analyses, the licensee was requested to discuss whether another channel trip i
function without dynamic components could provide the same protection.
in the licensee's response, dated July 1,1997, the licensee identified five safety relate protection channels that use dynamic components. These channels are:
Over temperature Delta T
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Overpower Delta-T Pressurizer Pressure Low Steamline Pressure Low Low-Low Twg Eleven Chapter 15 events depend on at least one of the first four of these protection channels for a primary trip. The Low Low Tavg trip is not credited in any of the Chapter 15 events. Of the 11 events identifed by the licensee, the alternate trip for 5 events would require a channel that also contains dynamic components. These five events are:
Inadvertent ECCS Operation at Power (DNBR Case) inadvertent ECCS Operation at Power (Pressurizer Fill Case) faadvertent Opening of Pressurizer Safety or Relief Valve
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Steam Generator Tube Rupture (Offsite Dose Case)
Steam Generator Tube Rupture (Margin to Overfill Case) 9905190107 990513 PDR ORG NE TOP PDR 2
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Brian Sheron - 3 The staff concluded that the number of Chapter 15 events that depend only on safety functions that use dynamic components justified heightened attention to channel calibration procedures and the processes of periodically checking the accuracy of each component to ensure channel operability.
In the May 5,1997, request for additionalinformation, the staff also requested a description of the process used to account for dynamic component setpoint uncertainties in the Braidwood UFSAR accident analyses. In response, the licensee stated:
The setpoint methodology used by Byron and Braidwood is consistent with the Westinghouse safety analyses. The equations used to determine the channel statistical analysis term, or total channel error, and the associated allowable value do not incorporate specific terms for dynamic component uncertainties.
Additionally, the licensee stated that dynamic testing ensures that the channel will trip within the required tolerance, whether the errors in tha channel are from stat" components or from dynamic components.
The Braidwood and Byron TSs require periodic trip actuating device operability tests to verify operability of alarm, interlock and/or trip functions. These trip actuating device operational tests include adjustment, as necessary, of trip actuating devices such that each device actuates at the required setpoint within the required accuracy. As stated in the licensee's response, the required (TS) accuracy values (which are the only test
' acceptability criteria) are based solely on static component accuracies.
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'b Brian Sheron - 4 in the Braidwood TS, Operability is defined as follows:
4 1.19 A system, subsystem, train, component or device shall be OPERABLE or have OPERABILITY when it is capable of performing its specified i
I ftinction(s), and when all necessary attendant instrumentation, controls, electrical power, cooling or seal water, lubrication or other auxiliary equipment that are required for the system, subsystem, train, component, or device to perform its function (s) are also capable of performing their related support function (s).
i In a conference with the licensee on October 15,1997. the staff discussed dynamic testing at Braidwood, in this discussion, the staff stated that only the channelinput and output signals are recorded. Consequently, operators cannot distinguish between static module inaccuracies and dynamic module inaccuracies. The staff asked the licensee whether this could prevent the operator from making a correct determination of channel operability based on TS allowable values, which are the only acceptance criteria for the channel operability tests. The ' sis of the staff's reasoning was that the operator's determination of channel operability might be adversely affected if the dynamic components mask the behavior of the static components, in response to this assumption, the licensee responded that this condition exists in every test regardless of the inclusion of dynamic components in the instrument string.
Furthermore, the licensee stated, including the dynamic components in the channel functional test and using only the static component uncertainties to define the acceptance criteria for the tests places tighter constraints on channel calibration tolerances, and is
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.g UNITED STATES g
j NUCLEAR REGULATORY COMMISSION o
t WASHINGTON, D.C. 20555-0001
\\*****4t June 4, 1998 4
MEMORANDUM TO: Frederick H. Burrows, Electrical Engineer I
Electrical Engineering Branch 1
Division of Engineering
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Office of Nuclear Reactor Regulation j
L. Joseph Callan kb FROM:
Executive Director forbperations
SUBJECT:
REQUEST FOR REVIEW OF CONCERNS RELATED TO TECHNICAL SPECIFICATION SETPOINTS AND ALLOWABLE VALUES FOR INSTRUMENTATION UNDER FORMAL DIFFERING PROFESSIONAL OPINtON PROCEDURES I
l Your letter to me dated May 21,1998, requested that the use of allowable values to determine operability for safety-related instrumentation channels in lieu of channel trip setpoints in technical Specifications be reviewed under formal Differing Professional Opinion (DPO) procedures. I have reviewed the circumstances surrounding the Differing Professional View (DPV) that you submitted on the same subject. I have concluded that the DPV process has not been j
completed, in that the recommendations of the DPV panel, as discussed in the memorandum from the Acting Director of the Office of Nuclear Reactor Regulation (NRR) dated October 31, j
1997, have not been responded to in the form of action items and schedules for completion.
j Therefore, the DPO is being sent to the Director of NRR to be processed as part of the still-open j
DPV.
As I expressed to you in my memorandum on dynamic testing of instrumentation at Braldwood, dated May 6,1998, I can appreciate your frustration with the time that has pas. sed without closum. I have requested that the Director of NRR provide me with a list of action items and dates by which they wiB be completed. Further, I have requested that a high priority be placed on resolution because continued approval of improved Standard Technical Specifications before j
final resolution of your lasue may exacerbate the Agency's problem. I have attached a copy of 1
that letter for yourinformation.
I trust that this will resu4 in a resolution of your issues. Again, thank you for participating in the Differing Professional Opinion process. Your willingness to bring your concems to management's attention directly contributes to achieving the Agency's safety mission.
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Attachment:
As stated I
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