ML19260C550
| ML19260C550 | |
| Person / Time | |
|---|---|
| Site: | Grand Gulf  |
| Issue date: | 12/18/1979 |
| From: | Baer R Office of Nuclear Reactor Regulation |
| To: | Stampley N MISSISSIPPI POWER & LIGHT CO. |
| References | |
| NUDOCS 8001070444 | |
| Download: ML19260C550 (12) | |
Text
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NUCLEAR REGULATORY COMMISSION o
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a Docket Nos. 50 aN DEC 18 O and 50-417 I
Mr. N. L. Stampley, Vice President Production and Engineering Mississippi Power and Light Company l
P. O. Box 1640 Jackson, Mississippi 39205
Dear Mr. Stampley:
l
SUBJECT:
REQUESTS FOR ADDITIONAL INFORMATION (Grand Gulf Nuclear Station, Units 1 and 2)
As a result of our review of the information contained in the Final Safety Analysis Report for the Grand Gulf Nuclear Station, Units 1 and 2, we have developed the enclosed requests for additional information.
I i
We request that you amend your Final Safety Analysis Report to reflect your i
responses to the enclosed requests by February 28, 1980.
If you cannot meet this date, please advise us of the date you can meet as soon as possible so that we may consider the need to revise our review schedule.
Please contact us if you desire any discussion or clarification of the enclosed requests.
Sincerely,
.,. f., { {..~/'
"i Robert L. Baer, Chief i
Light Water Reactors Branch No. 2 Division of Project Management
Enclosure:
Requests for Additional Information ces: See next page 1694 145 800L070k
/
~b Mr. II. L. Stampley '
- ..- t etg7g Mr. fl. L. S tampley Vice President - Producti co Mississippi Power and Lignt Comcany P. O. Box 1640
. Jackson, Mississippi 39205
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Mr. Robert B. McGenee, Attorney ccs:
Wise, Carter, Child, Steen and d
Caraway P. O. Box 651 Jackson, Mississicci 39205 Troy B. Conner, Jr., Esq.
Conner, Moore and Corber 1747 Pennsylvania Avenue,.'l.11.
Washington, D. C.
20006 Mr. Adrian Zaccarii, Project Engineer Grand Gulf tiuclear Station Bechtel Power Corporation Gaithersburg, Maryl and 20760 1694 146 9
DEC 13 $I3 031.48 - Inconsistencies in section 7.2 make it impractical, if not impossible, to determine whether the RPS is in com-pliance with NRC requirements.
The following illustrations of types and magnitudes of inconsistencies are provided as examples.
(1)
In the introduction to the RPS, the instrumentation is identified as being a part of either sensor trip channels, trip logic divisions, or actuator output logic divisions.
In the remainder of 7.2 at least 20 variations (including some commutations and permutations) are used in identifying some portion of the instrumentation.
(2)
Protection system cabling is discussed in 7.2.1.1.4.2, 7.2.1.1.4.7, 7.2.1.1.7, 7.2.2.1.1.1, 7.2.2.1.2.1.10, 7.2.2.1.2.3.1.2 and 7.2.2.1.2.3.1.7.
At various places in these sections the same cable run is pur-ported to be in:
(1) wireways, (2) conduit, (3) separate conduit for each division, (4) separate conduit for each device, (5) separately from any other cabling, and (6) in conduit and wireways.
In a few individual instrument descriptions cabling is identified only as being " routed from the transmittern to the main control room".
(3)
Your response to question 031.031 indicates that you utilize one of three different isolation devices (two digital and one analog) to isolate each protective system signal that interfaces to nonprotective systen 1694 147 D**]D D) 1 ( L T YM" woA
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DEC 1 J St ji Circuits.
Each of these isolation devices is identified as utilining optical isolators as the isolation barrier.
In section 7.2 the following terms are used to describe isolation devices in the RPS:
(1) electronic isolators (2) electronic isolation devices (3) electrical isolation Revise section 7.2 to make it self-consistent and correct.
In the case of isolation devices we would prefer to refer to all three devices described in section 7.1 as optical isolation; additional or alternate isolation, such as separate relay contacts should be specificallv identified.
031.49 - Provide a discussion of the code switch in section 7.2.1.1.4.2.
Provide at least the same detail as pro-vided for other RPS initiating circuits.
Figure 7.2-2 (the reference drawing for section 7. 2.1.1. 4. 2) shows the mode switch as both.an initiator and a modifier of other initiators of the RPS.
The discussion should include as a minimum:
(1)
The design features used to maintain separation of trip logic divisions and to isolate RPS functions of the switch from non-RPS functions.
(2)
The mechanism used to introduce a scram with the mode switch and t ie n echanism used to bypass this scram.
1694 148
DEC '. f 1979 (3)
The specific way that the mode switch interacts with the individual initiator channels shown in Figure 7.2-2 as having the mode switch as a modifying agent.
(4)
A figure or table identifying the location and use of every contact in one bank of'the mode switch.
Reference to an existing table or figure is acceptable provided the discussion provided can be understood without reference to the figure or table.
The discussion of the mode switch in other sections of 7.2 should be modified as necessary to be consistent with the discussion provided for section 7.2.1.1.4.2.
In particular, if the interaction of the mode switch is at the trip relay level (as indicated in Figure 7.2-5) do not say that the switch connects (and by inference disconnects) " appropriate sensors into the RPS Logic."
031.50 The claims made in the name of " diversity" indicate a misunderstanding of the meaning of diversity.
The following mis-statements on diversity are from sections 7.2.1.1.4:
(1)
"These variables are independent of one another and provide diverse protective action for this condition.
This statement, or almost identical ones, is made four times.
In most cases diverse protection is possible because the diverse variables are not inde-pendent.
Diverse protection is not possible unless the diverse variables are dependent variables of the 1694 149
DEC 1S 079 incident being protected against.
Also " diverse protective action" is not provided; the same pro-tective action, a scram, is provided by all u
initiators.
(2)
" Diversity is achieved with physical separation of the manual reset switches, which requires deliberate operator action to initiate the reset of the RPS logic."
If this is diversity, every one of the protective circuits have.it.
In addition, two references to diversity discussions are included in the discussion of operating bypasses.
In each case the circuit involved is in an interlock function rather than a protective function.
In one case the referenced discussion indicates that there is no diversity Two conditions are necessary for there to be diversity between two initiator circuits.
First, the two initiator circuits must sense the approach to unsafe levels by different means (either by sensing different variables or by sensing the same variable with a sensor of different principle), and second, each of the two initiators must initiate protective action in time to prevent unacceptable results.
Please amend your statements of diversity to identify t!,e specific incidents for which diverse protective action is provided.
Also, amend the incident descriptions and 1694 150
OEc I 8 R79 transients to include the transients that would exist if the least effective of the diverse circuits was the only circuit to function.
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031.51 - In sections 7.2.1.1.4.3 and 7.2.1.1.4.4.5, you claim that redundancy is provided for both the scram reset operation and the automatic scram bypass (active only with mode switch in shutdown) through the use of four separate actuating devices.
If redundancy is provided, amend the FSAR to identify:
(1) how redundancy is achieved, (2) whether redundancy is provided by an actuator in the same trip division, and (3) the steps taken to isolate the reset (or bypass) action for one trip logic from the other trip logics obtaining redundant reset (or bypass) from the same actuating device.
If the circuits are independent rather than redundant, amend the FSAR to indicate indepen-dence and compliance with single failure criteria.
Section 7.2.1.1 states that there are four reset switches in the scram reset cire.t in one paragraph, but in another paragraph implies a single reset switch (plural reset actions are attributed to operation of a single reset switch).
Section 7.2.2.1 also refers to "the RPS reset switch."
Resolve this discrepancy and amend the FSAR accordingly.
Revise the presentation in 7.2.1.1 en include a discussion of how separation is accomplished within and between trip divisions.
Include a schematic diagram or provide reference drawing numbers.
1694 151
F.C 1 8 l'.3/4 031.52 - Section 7.2.2.1.1.1.6 and Section 15.4.4 identify with-drawal of the maximum worth rod as the limiting control rod withdrawal transient for determining the minimum number and location of LPRM detectors for the APRM channels.
Since the maximum worth rod is near the radial center of the core, the flux increase will be fairly near uniform except in the vicinity of the with-drawal control rod.
On the other hand, a control rod further from the center will generate a tilt in the power distribution that will result in a higher ratio of local power increase to average power increase since the LPRM's will on the average, be further from the source of the perturbation.
Identify the calculations made to support the contention that the maximum worth control rod is the most restrictive control rod tran-sient as far as influencing the number and location of LPRM detectors for an APRM channel.
031.53 - Revise the discussion of compliance with IEEE Std. 279 to identify any portion of the RPS that does not comply.
If your analysis indicates that there is full compliance, this should be stated in Section 7.2.2.1.2.3.1 prior to the presentation of the analyses used to determine that individual portions of the RPS comply with specific requirements of IEEE Std. 279.
1694 152
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031.54 - Revise the tables and figures in Section 7.2 to remove the errora and inconsistencies noted below:
(1)
The title of Table 7.2-1 is incorrect as the table does not specify anything but the trip setting and trip repeatability.
(2)
Identify " Trip Setting" in Table 7.2-1 further.
Are these settings your expect to use or are they the span of the trip point adjustment?
Does the
" Normal Range" refer to the " Instrument" or to the normal value during reactor operation?
Is the
" Trip Setting" related to the transmitter output or to the actual sensed reactor vessel pressure (or level) at the time that trip is generatec, with signal changing at the rate indicated uncer "tran-sient".
(Does the setpoint include the change in pressure during the response time of the RPS?)
" Trip Setting" is an ambiguous term in relation to bypass functions, " Required Conditions" would be more meaningful.
The accuracy figure for the turbine stop and control valve trip bypass should be in 7. power for consistency.
(3)
Resolve the discrepancy in Reactor Vessel High Pressure setpoint between tables 7.2-1 and 7.2-4.
(4)
Provide justification for those trip functions in Table 7.2-4 that claim zero (or conservative direction only) instrument and setpoint drift.
1694 153
'EC1e?)79 (5)
Resolve the discrepancies between the transient overshoot claimed in Table 7.2-4 and the values shown in various figures in Chapter 15.
(6)
Justify the use of a " Maximum Overall" response time for the APRM that is less than the sum of the " Design" values for the channel and the logic-actuator.
Identify the meaning of " Design Response Times" in the context of whether these are maximum acceptable values, nominal values, etc. s.nd how they are related to " transients" in Table 7.2-1.
Justify the exclu-sion of the flow weighted APRM neutron flux trip from the table.
(7)
Revise Figure 7.2-2 to show that the APRM trip is not only operable in other modes than Run but that the setpoint is lower if the mode switch is not in Run.
(8)
Revise Figure 7.2-5 to correct the error in contact condition for contacts E and G (the contacts should be closed) in the turbine stop valve closure channel.
(This error has been noted in a number of other BWR FSAR's.)
(9)
Resolve the discrepancy in the APRM trip functions between Figure 7.2-6 and Figure 7.6-12.
/(10)
Steam line B, Outboard Valve is misidentified in the key to Figure 7.2-8.
1694 154
> > iq 031.55 Your renponue to Question 031.12 indicates that Table 7.1-3 identiften th applicable safety criteric for Chapter 7, and; footnote
- 3 of this table indicates that the degree of conformance is discussed in the analysis (7.X.2) Sections. Each of the 7.1.2 Sections for individual systems indicaten that all requirements identified to Tabic 7.1-3 are met.
Additionally tables 7.1-4 through 7.1-9 present information similar to but not fully in agree-ment with th? information in Table 7.1-3.
None of the tables have descriptive t' tles that indicate any more than the protective system involved (con, do not identify the significance of the "X" symbols).
Amend your FRAR as necessary to achieve consistency between the various 7.X.2 Sections and the seven tables.
In discussing conformante, distinguish between full conformance and conformance with exceptions. A specific statement of the degree of con,formance to the 10 CFR requirements identified in Table 7.1-3 is required.
The staterent of conformance may be made in the individual 7.X.2 Sections or in 7.1.2 for all systems, but should not replace the supportive diFcussion currently in 7.X.2 Sections. In addition, the follevina specific comments are made.
(Review of Sections 7.3-7.7 has not Non made):
(1)
Table 7.1-3 is erroneously referred to as Table 7.3-1 in 7.1.2.
(2)
Section 7.2.2.1.2.2.2 presents features that tre necessary and desirshle, but they do not relate to the subject of GDC 12 (Suppresnion of reactor power transients) in a readily 1694 153 recop,ntnable manner.
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Orc $ " 1979 (3) Section 7.2.2.1.2.2.3 does not cortmit to having provided adequate instrumentation to follow accident nor to having provided instru-mentation with adequate range to monitor the variables over anti-u operational occurrences and eccident conditions.
(4)
Se ction 7.2.2.1.2.2.11 says a lot of good things, but it does not address the role of the reactor trip system for a " single mul-function of the reactivity control systems" which is the subject of GDC 25.
O 1694 156