ML16342B903
| ML16342B903 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 08/05/1992 |
| From: | Rood H Office of Nuclear Reactor Regulation |
| To: | Rueger G PACIFIC GAS & ELECTRIC CO. |
| References | |
| REF-GTECI-070, REF-GTECI-094, REF-GTECI-NI, TASK-070, TASK-094, TASK-70, TASK-94, TASK-OR GL-90-06, GL-90-6, TAC-M77347, TAC-M77348, TAC-M77417, TAC-M77418, NUDOCS 9208120183 | |
| Download: ML16342B903 (12) | |
Text
~P,S REgIj (4
P0 A.0O IVl O~
e+n ++*++
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 August 5,
"~992 Docket Nos.
50-275 and 50-323 Mr. Gregory M. Rueger Nuclear Power Generation, B14A Pacific Gas and Electric Company 77 Beale Street, Room 1451 P.O.
Box 770000 San Francisco, California 94106
Dear Hr. Rueger:
SUBJECT:
STAFF REVIEW OF GENERIC LETTER 90-06, "RESOLUTION OF GENERIC ISSUE 70,
'POWER-OPERATED RELIEF VALVE AND BLOCK VALVE RELIABILITY,'ND GENERIC ISSUE 94,
'ADDITIONAL LOW-TEMPERATURE OVERPRESSURE PROTECTION FOR LIGHT-WATER REACTORS,'URSUANT TO 10 CFR 50.54(f)"
(TAC NOS.
- H77347, H77348,
- M77417, AND M77418)
By letters dated December 21,
- 1990, and March 27,
- 1991, the Pacific Gas and Electric Company (PG&E) responded to Generic Letter 90-06.
The generic letter represented the technical resolution of two generic issues and included plant backfits which were cost-justified safety enhancements, Generic Issue 70 included upgrades in quality requirements, inservice testing requirements, and
,modified technical specifications for all pressurized water reactor facilities that incorporate PORVs and block valves in their design.
The intended purpose was to enhance the overall reliability of the PORVs and block valves so that they could better perform the safety functions identified in the generic letter.
Generic Issue 94 included modified technical specifications for all Westinghouse and Combustion Engineering facilities to reduce the allowed outage time for an inoperable LTOP channel and thus reduce the probability of overpressurization events during shutdown conditions.
The staff has reviewed your submittals and finds that they do not meet selected portions of the generic letter.
It is the staff's position that a
regulatory analysis has been performed in accordance with 10 CFR 50. 109(a)(3) and 50. 109(c) which justifies the backfit.
Therefore, absent any information that demonstrates that your facility is not bounded by the regulatory analysis that accompanied the generic letter, you are requested to resubmit a response that is in keeping with the intent of the generic letter.
The specific areas of concern are as follows.
1.
Testing of PORV Control Air Valves The staff position requires that valves in PORV control air systems be included within the scope of a program covered by Subsection
- IWV, "Inservice Testing of Valves in Nuclear Power Plants," of Section XI of the ASME Boiler and Pressure Vessel Code.
Your submittal did not adequately meet this staff position.
Specifically, your Safety MRC FKKHBK&V
~
~
p~( [f]~, y pe
Hr. Gregory H. Rueger 2.
Evaluation states that the proper operation of the solenoid air control valves is verified by stroke testing the PORV.
However, the staff is not accepting the position that successful completion of the PORV stroke test indirectly verifies operability of the control air valves.
Host plant configurations which have air-operated PORVs include both a
normal (nonsafety) air supply and a safety backup (either air or nitrogen accumulator) supply.
The intent of this testing is to assure the capability of the safety backup supply.
In addition, the air check valves which isolate the safety backup accumulator supply in the event of loss of normal air supply should also be tested.
A consideration regarding control air valves is found in Generic Letter 89-04 which was issued to provide guidance on IST.
Because some components, such as these control air system valves, may not be classified as ASHE Class 1,
2, or 3 components, they may not be included in the ASHE Code IST programs.
This is addressed in Attachment 1 of GL 89-04, Item No.
11.
In accordance with this guidance, it is an acceptable alternative to test these noncode class components as required in plant test procedures, outside the IST program.
Therefore, commitments to this effect are acceptable.
In order to assure the capability of the safety backup (either air or nitrogen accumulator) supply to adequately operate the
- testing, or the valves in the safety backup supply, including the check valves which isolate the safety backup and normal supplies, should be individually tested to assure their capability.
If these components are not tested in the IST program, they should be periodically tested and verified according to other specific plant testing procedures.
In your
- response, discuss how you intend to verify the capability of the valves in the safety backup supply.
Staff Guidance on Mode for 18-Month PORV Stroke Test The staff position requires the 18-month PORV stroke test to be performed during Mode 3
(HOT STANDBY) or Mode 4
(HOT SHUTDOWN) and in all cases prior to establishing conditions where the PORVs are used for low-temperature overpressure protection.
Your submittal did not adequately meet this staff position.
Your proposed Surveillance Requirement 4.4.4.
1 does not specify mode.
While the accompanying safety evaluation indicates that current administrative controls ensure that the PORVs are tested in Mode 4, it also indicates that the proposed surveillance requirement allows the flexibilityto test the valves in any mode following maintenance.
However, the staff is not accepting Mode 5
(COLD SHUTDOWN).testing simply because it is allowable by the ASME Code or that the NRC approved IST program includes Mode 5 for this particular test.
The requirement to perform stroke tests of the PORVs during Modes 3 or 4
is a new position for some licensees.
The basis for this position lies in the uncertainty introduced by stroke testing the PORVs at lesser
E
Mr. Gregory M. Rueger 3.
system temperature conditions and then expecting them to perform adequately at operating system conditions.
If this recommendation is not adopted, a sound technical basis should be provided (e.g., that such testing cannot be performed without significant system modifications or that the intent of such testing is accomplished by some other means).
We note that one licensee has proposed the option to bench test the PORVs.
This would be acceptable, provided the tests are performed at conditions simulating Mode 3 or 4 conditions or greater and provided the proper reinstallation of the PORVs and controls is verified.
In another
- case, the staff accepted an argument from a licensee that the physical distance between the PORV and the pressurizer maintained the same temperature at the PORV in Modes 3, 4, or 5 such that there is no difference from the valve's perspective of testing in different modes.
In this case, the facility had an air-operated PORV and was able to perform the PORV stroke test with the block valve closed, such that the PORV would be primarily influenced by the ambient room conditions.
Additionally, the GL required that PORVs be stroke tested in all cases prior to establishing conditions where the PORVs are used for low-temperature overpressure protection.
This could be.interpreted to mean that PORVs should be stroke tested during every shutdown and again during every startup.
- However, the inclusion of the PORVs in the IST program requires the valves be tested no more frequently than every three months (unless valve maintenance is performed) to demonstrate operability.
In summary, the staff maintains its position that the PORVs should be stroke tested during Modes 3 or 4 in order to verify the capability to function in an environment more representative of operating conditions.
In your revised
- response, discuss how PORV stroke testing provides assurance that the PORVs will perform all necessary safety functions adequately at the required system operating conditions.
LTOP Technical Specification Upgrades The staff position for the resolution of Generic Issue 94 included the technical specification upgrades as presented in the generic letter.
The staff review determined that you have significantly modified the staff's model technical specification given in the generic letter.
Specifically, you are proposing a 72-hour allowed outage time for restoring a
PORV to operability in Modes 5 or 6, where the generic letter recommends 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.
However, the staff will not accept, without significant technical justification, statements that the maximum allowed outage time will not support flexible plant operations.
In addition, the staff will not accept PRA-based arguments to expand allowable outage times.
Only differences in plant hardware relative to that assumed in the staff's cost/benefit analysis will be considered.
It is our position that in view of the recently completed regulatory analysis supporting the proposed outage times, and the uncertainties inherent in PRA analyses, that consideration of PRA-based arguments (which is tantamount to reopening the issue) is not warranted.
~
~
Jl
~l I
Mr. Gregory M. Rueger The intent of the resolution of Generic Issue 94 was to decrease the probability of cold overpressurization while in a water-solid condition by increasing the availability of the low-temperature overpressure protection (LTOP) system.
Generic Issue 94 did not apply to Babcock Wilcox (B&W) facilities because they maintain a nitrogen bubble in the pressurizer and do not operate in a water-solid condition.
Similarly, the staff would be receptive to extending the recommended 24-hour allowed outage time with an inoperable LTOP channel to 7 days provided the plant is not water-solid.
For such cases, the licensee must identify a pressurizer level which provides a level of protection against cold overpressurization comparable to that provided by the nitrogen bubble in B&W facilities.
Therefore, based on the additional guidance provided above, you are requested to resubmit your response to the generic letter.
You are requested to respond within 60 days following receipt of this letter.
If you would like to further discuss these issues prior to your resubmittal, please feel free to contact me
~
The information requested by this letter is within the scope of the overall burden estimated in Generic Letter 90-06 for the resolution of Generic Issue 70 and Generic Issue 94, which was a maximum of 320 person-hours per licensee response.
This request is covered by Office of Management and Budget Clearance Number 3150-0011, which expires May 31, 1994.
Sincerely, Harry R od, Senior Project Manager Project Directorate V
Division of Reactor Projects III/IV/V Office of Nuclear Reactor Regulation cc:
See next page
Mr. Gregory M. Rueger Pacific Gas and Electric Company Diablo Canyon CC:
NRC Resident Inspector Diablo Canyon Nuclear Power Plant c/o U.S. Nuclear Regulatory Commission P. 0.
Box 369 Avila Beach, California 93424 Dr. Richard Ferguson, Energy Chair Sierra Club California 6715 Rocky Canyon
- Creston, California 93432 Ms. Sandra A. Silver Mothers for Peace 660 Granite Creek Road Santa Cruz, California 95065 Ms. Jacquelyn C. Wheeler 3303 Barranca Court San Luis Obispo, California 93401 Managing Editor The County Telegram Tribune 1321 Johnson Avenue P. 0.
Box 112 San Luis Obispo, California 93406 Chairman San Luis Obispo County Board of Supervisors Room 370 County Government Center San Luis Obispo, California 93408 Christopher J.
- Warner, Esq.
Pacific Gas
& Electric Company Post Office Box 7442 San Francisco, California 94120 Mr. Hank Kocol Radiologic Health Branch State Department of Health Services Post Office Box 942732 Sacramento, California 94234 Regional Administrator, Region V
U,S. Nuclear Regulatory Commission 1450 Maria Lane, Suite 210
.Walnut Creek,'alifornia 94596 Mr. Peter H. Kaufman Deputy Attorney General State of California 110 West A Street, Suite 700 San Diego, California 92101 Ms. Nancy Culver 192 Luneta Street San Luis Obispo, California 93401 Michael M. Strumwasser, Esq.
Special Assistant Attorney General State of California Department of Justice 3580 Wilshire Boulevard, Room 800 Los Angeles, California 90010
0 j
4 J
-. Ar. Gregory M. Rueger A~st 5, 1992 The intent of the resolution of Generic Issue 94 was to decrease the probability of cold overpressurization while in a water-solid condition by increasing the availability of the low-temperature overpressure protection (LTOP) system.
Generic Issue 94 did not apply to Babcock Wilcox (B&W) facilities because they maintain a nitrogen bubble in the pressurizer and do not operate in a water-solid condition.
Similarly, the staff would be receptive to extending the recommended 24-hour allowed outage time with an inoperable LTOP channel to 7 days provided the plant is not water-solid.
For such cases, the licensee must identify a pressurizer level which provides a level of protection against cold overpressurization comparable to that provided by the nitrogen bubble in B&W facilities.
Therefore, based on the additional guidance provided
- above, you are requested to resubmit your response to the generic letter.
You are requested to respond within 60 days following receipt of this letter.
If you would like to further discuss these issues prior to your resubmittal, please feel free to contact me.
The information requested by this letter is within the scope of the overall burden estimated in Generic Letter 90-06 for the resolution of Generic Issue 70 and Generic Issue 94, which was a maximum of 320 person-hours per licensee response.
This request is covered by Office of Management and Budget Clearance Number 3150-0011, which expires May 31, 1994.
Sincerely, Orgloal Signed By:
cc:
See next page Harry Rood, Senior Project Manager Project Directorate;,V Division of Reactor'Projects III/IV/V
'ffice of Nuclear Reactor'egulation DISTRIBUTION
~Docket File---+
PD5 Reading MVirgilio NRC
& Local PDRs OGC DPickett ACRS(10)
HRood PD5 p/f BBoger TQuay DFoster RFrahm GHammer
- PJohnson, RV
- KPerkins, RV OFC DATE PDV/LA DFoster 5 /
/92 PDV/PM HRood:lh 8/
92 PDV/D TQuay F/5 /92 OFFICIAL RECORD COPY DOCUMENT NAME: DC77347,RAI
4 fp l'I