ML20004E229
| ML20004E229 | |
| Person / Time | |
|---|---|
| Site: | Trojan File:Portland General Electric icon.png |
| Issue date: | 06/08/1981 |
| From: | Withers B PORTLAND GENERAL ELECTRIC CO. |
| To: | |
| Shared Package | |
| ML20004E227 | List: |
| References | |
| TAC-11298, NUDOCS 8106110376 | |
| Download: ML20004E229 (9) | |
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PORTLAND GENERAL ELECTRIC COMPANY EUGENE WATER & ELECTRIC BOARD AhT PACIFIC POWER & LIGHT COMPANY TROJAN NUCLEAR PLANT Operating License NPF-1 Docket 50-344 License Change Application 73 This License Change Application requests modification of Technical Specifications 3.7.10.1, 4.7.10.1, and the corresponding Technical Specification Bases contained in Appendix A to Operating License NPF-1 in order to upgrade the snubber surveillance requirements for the Trojan Nuclear Plant.
PORTLAND GENERAL ELECTRIC COMPANY
--s By Bart D. Withers Vice President i
Nuclear Subscribed and sworn to before me this [b day of v
1981.
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My Commission Expires:
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6 LCA 73 o
Page 1 of 7 LICENSE CHANGE APPLICATION The proposed replacement pages to Appendix A of Facility Operating License NPF-1 are provided as Attachment 1.
A description of these changes follows:
(1) Page 3/4 7-32.
Section 3.7.10.1 has been changed to incorporate operability requirements for mechanical snubbers. Applicability was extended to Modes 5 and 6 for snubbers on systems required to be OPERABLE during these Modes. The action statement has also been changed to be based upon the ACTION statement for the system that the inoperable snubber is located on, instead of requiring the Plant to be placed in HOT STANDBY followed by COLD SHUTDOWN for cases in which the snubber cannot be replaced or restored within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.
This section will differ from the NRC model Technical Specification for snubbers in that it does not include a mandatory requirement for an engineering evaluation to be performed per tr.e guidelines given in Specifi-cation 4.7.9.c of the model Technical Specifications; nor is a functional test required in all cases.
There could be instances where the cause of iroperability is obvious. For example, the cotter key may have fallen out causing the retaining pin to drop out, rendering the snubber inoperable.
Inserting the retaining pin and the co..er key will make the snubber operable for the affected system. In addition, functional testing may result in high man-rem exposures that would be centrary to ALARA.
The proposed change allows the option of performing an evaluation to determine system operability, or following the affected system ACTION statement for direction on what must be done in the event a snubber is found to be inoperable. This will provide increased flexibility in cases where further analysis and/or functional testing is not warranted by the cause of failure, and in cases where built-in l
margins result in systems being operable even though a l
snubber may be inoperable.
l (2) Page 3/4 7-32, 33, and 36.
Section 4.7.10 (including Paragraphs 4.7.10.la, b, e and Table 4.7-4) was substan-tially modified as.shown in Attachmert.1.
A summary of the revised paragraphs follows:
r (4.7.10.1).
Surveillance N,L'2g ill be required for mechanical as well as hyd.cv b
,bbors on safety-related systems.
A refere7:e to ce;eion 4.0.5 was also included which will require snubber inspection in accordance with the inservice inspection program in addition to the inspection required by the proposed Technical Specification.
LCA 73 Page 2 of 7 (4.7.10.1.a).
Visual inspections will be requ.< red on a routine basis. All of the snubbers listed in Ta'sles 3.7-5a and 3.7-5b will have to be visually inspected during the first two inspection periods.
Thereafter, sampling sizes and visual inspection frequencies will be based upon the number of snubbers found to be inoperable within the particular snubber categories. Categorization of the snubbers into groups and subgroups will be based on physical characteristics, environmental conditions, accessibility, and combina-tions of these characteristics. This will allow focusing of future sampling plans on those snubbers that may be subjected to a previously identified failure mode.
On the other hand, the proposed inspection plan will also allow a reduction in inspections for those snubbers that have consistently demonstrated a high degree of reliability.
The model Technical Specification require-ment to perform the first visual inspection 4 to 10 months after commencing power operation was not included in the proposed change, since Trojan has been commercial since May 20, 1976.
The inspection schedule given in current Technical Specification Table 4.7-4 is similar to that in the proposed Section 4.7.10.1.a.
The first visual inspection performed under this program will begin during the first refueling outage commencing after issuance of the Technical Specifica-tion amendment incorporating this program.
(4.7.10.1.b).
Visual inspection acceptance criteria have been included in the proposed change. They are ba ed en visual indications of damaged or impaired operability to the snubbers and on visual verification char attach-ments to foundations or supporting structures are secure.
This section does not include the model Tech-nical Specification requirement for functional testing where snubber movement can be manually induced without l
disconnecting the snubber to verify that the snubber has freedom of movement and is not frozen up.
This would imply that the snubber could be moved within the freedom of motion in the bearing, and from this a determination could be made on whether it is moveable through its full range. Movement of the larger sizes of snubbers is not possible due to the high breakaway force involved.
Also, Pacific Scientific snubbers have a dead zone which is the distance of travel before l
the balls shift and start on the reverse course of the
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lead screw (somewhere around 0.04 inches). Hence, movement of the snubber within the dead zone can be achieved without proving that the snubber is functional.
In addition, the purpose of this section is to detect visual damage, and functional testing requirements are included in Section 4.7.10.1.c.
Therefore, the require-ment for manual exercising was not included in this l
section of the proposed change to the Technical l
Specificat ans.
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LCA 73 Page 3 of 7 This section also differs from the model Technical Specifications in that it does not require functional testing of all snubbers that were found to be inoper-able.
Once again this is due to ?e fact that some failures may be due to obvious ca 7 :,es with obvious remedies such as the retaining pin falling out due to the missing cotter pin.
(4.7.10.1.c).
Functional testing of at least 10 per-cent of each type of snubber is required at least once per 18 months during shutdown. Additional sampling (in the corresponding snubber category) of at least one-half the size of the original sample is required for each snubber found to be inoperable.
Hydraulic snubbers greater than 50,000 pound capacity have been exempted from functional testing.
These snubbers would have to be removed and shipped offsite for testing. Removal and installation of these snubbers would be very time consuming and difficult. High man-rem exposures would result due to their inacces-sibility and location in high radiation zones.
The alternate sanpling size suggested by the model Technical Specifications was not included in the proposed change since it was primarily intended for plants with more than 500 snubbers. The proposed change does require that at least 25 percent of snubbers in
-the ~aitial functional testing sample include those snubbers within 5 feet of heavy equipment and those snubbers within 10 feet of the discharge of a safety relief valve.
Sampling from these two groups is required in the initial sample only.
Any additional sampling due to inoperable snubbers will be directed to those cate-gories or subcategories which contain the failed snubbers.
The model Technical Specification includes the first snubber away from each reactor vessel nozzle as part of the initial sample population. This was not included in the proposed change since snubbers are not used on the main reactor coolant lines at Trojan.
The proposed change will require testing of inoperable snubbers during the next testing period in addition to the regular sample. The results of the testing of the previously inoperable snubbers will be kept separate from the regular test sample in order to focus attention on these snubbers. The proposed change also requires that if any snubber fails to lock up or fails to move, i.e.,
is frozen in place, the cause will be evaluated for further action or testing.
It does not include the model Technical Specification requirement for a mandatory engineering evaluation, including an evaluation of the effect on the supported components for the reasons previously stated.
LCA 73 Pege 4 of 7 (4.7.1.d).
Functional test acceptance criteria for hydraulic snubbers are included in the proposed change. They are based on activation velocities or accelerations and snubber bleed or release rates.
No changes to the model Technical Specifications were made.
(4.7.10.1.e).
Mechanical snubber functional test acceptance criteria are included in the proposed change. They are based upon verification that 1) the force required to initiate free movement of the snubber rod is less than the maximum drag force; 2) activation is achieved in both tension and compression; and
- 3) snubber release occurs in compression and tension.
This section does not include the model Technical Specification requirement to verify that the drag force has not increased by more than 50 percent since the last function test. Drag forces may increase by more than 50 percent between teses, especially for cases which involve low drag forces, and still be well within the maximum allowable drag force for the particular design.
Similarly, the measurement of activation levels and release rates is not required in the proposed change.
The activation level of Pacific Scientific snubbers will not exceed 0.02 g when subjected to loads in tension or compression up to the rated capacity. Regardless of the load, these snubbers will not lock up if the acceleration remains below 0.02 g.
They will permit movement if there is a sustained force in excess of the drag force. Verification that the mechanical snubbers will activate when required will be accom-plished by the proposed acceptance criteria.
(4.7.10.1.f).
The proposed section includes require-l ments for monitoring of snubber service lives. No exceptions to the model Technical Specifications were taken.
(3) Pages 3/4 7-34 and 35.
Table 3.7-5 has been divided into two sections, with Table 3.7-Sa including hydraulic snubbers and Table 3.7-5b including mechanical snubbers.
l The column heading entitled "HIGH RADIATION ZONE DURING l
SHUTDOWN" will be changed to read "HIGH RADIATION EXPOSURE ZONE" in order to include consideration of the time it takes for inspection and testing of snubbers in addition to the radiation levels at the snubber locations.
Snubber testing that results in excess of 0.1 man-rem l
exposure will be identified in this table. A modifica-tion to this table was also made in order to allow the addition or removal of snubbers without prior License Amendment regarding these tables, provided that the changes are included in the next License Amendment
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request.
LCA 73 Page 5 of 7 There are approximately 400 mechanical and hydraulic snubbers on safety-related systems at Trojan.
Identifi-cation and categorization of these snubbers is still in progress and, as a result, these tables will be submitted at a later date.
(The change to Table 3.7-5 identified in License Change Request (LCR) TNP-80-18 to correct a snubber number designation from SS-86 to SS-84 will be included in Table 3.7-5a.)
(4) Pages B 3/4 7-6 and B 3/4 7-7.
The Technical Specifica-tion Bases for Section 3/4.7.10 have been modified to reflect the changes noted above.
Changes to the model Technical Specification Bases regarding inoperable snubber evaluations were made for the reasona previously discussed. However, the underlying basis of ensuring that system integrity is maintained was not changed.
(5) Page 6-20.
A new section, 6.10.2.m, was added to require the maintenance of service life records for the snubbers listed in Tables 3.7-5a and 3.7-Sb.
These recom's will include the date at which service life commenced and associated installation and maintenance records.
No changes to the codel Technical Specifica-tions were made.
REASON FOR CHANGE The proposed change to the Trojan Technical Specifications is submitted in response to the NRC letter dated November 20, 1980 requesting changes l
to snubber surveillance requirements. Jelel Technical Specifications forwarded by the November 20 NRC letter and the draft industry standard on snubber testing were used as guidelines for this change.
SAFETY / ENVIRONMENTAL EVALUATION Summary of Change l
The proposed change embodies several changes to the Technical Specifica-l tion requirement for snubber surveillance.
The revised surveillance program includes visual inspections, functional testing, and service life monitoring for both hydraulic and mechanical snubbers.
New and/or upgraded inspection and testing acceptance criteria are also proposed by l
this change.
Effect on ALARA Considerations The addition of visual inspection and functional testing requirements for all the snubbers will increase the total man-rem exposures at Trojan.
Visual inspection and functional testing of all the mechanical snubbers alone may result in an estimated additional 30 man-rem exposure.
In order to reduce this figure whenever practical, visual inspection of snubbers that are inside Containment or are in High Radiation Exposure Zones will be performed during Plant shutdowns or when radiation levels are lowest.
LCA 73 Page 6 of 7 The snubbers will be categorized into groups and subgroups based on physical characteristics, environmental conditions, accessibility, and combinations of these characteristics.
In the event that no snubbers are found unacceptable within a group or subgroup for two successive visual inspections, the visual inspection sample size may be reduced accordingly.
-This will further act to reduce man-rem exposures.
If any of the snubbers are found to be inoperable as a result of the functional testing, an additional sample one-half the size of the initial sample will be tested.
Snubbers located in low radiation areas may be chosen preferentially over those in higher radiation areas when selecting snubbers for additional testing. This sampling program will detect common mode failures without having to manually test all of the snubbere and, therefore, will aid in keeping radiation exposures ALARA.
Finally, an exemption has been requested for hydraulic snubbers greater than 50,000 pound capacity. These large snubbers are all located inside Containment and would have to be removed and shipped of fsite for testing.
Removal and installation of these snubbers would be difficult and could result in significant radiation doses. This exemption will reduce man-rem exposures that result from the snubber surveillance program.
Effect on Technical Specifications and Technical Specification Bases Technical Specifications 3/4 7.10 and 6.10.2.m and the Technical Specifi-cation Bases for Section 3/4.7.10 will be changed as a result of this LCR.
These changes are shown in Attachment 1 and are discussed in the Description of Change section.
Functional testing of the snubbers will require unpinning of at least one end, which in turn renders the snubber temporarily inoperable.
Therefore, system operability will be affected by functional testing of the snubbers unless an evaluation shows that the system or train is operable without the snubber. Various sytems are l
required by the Technical Specifications to have one or two trains l
operable during Modes 1 through 4.
For example, Technical Specification 3.5.2 requires that at least two independent ECCS subsystems be operable in Modes 1, 2, and 3, and Technical Specification 3.5.3 requires that at least one ECCS subsystem be operable in Mode 4.
Certain systems and portions of subsystems are also required to be operable in Modes 5 and/or 6, such as the RHR System and a boron injection flow path. The snubber functional testing program must be conducted such that the Technical Specifications regarding system or train operability are not violated.
For example, snubbers on the flow path from the refueling water storage tank should be tested only during Modes 5 or 6, and not at the same time as snubbers on the flow path from the boric acid tanks in order to comply with Technical Specifications 3.1.2.1 and 3.5.5.
Also, snubbers on the RER loops should not be tested during Mode 6, when both loops are required to be operable in accordance with Technical Specification 3.9.8.2.
Functional testing of 10 percent of the snubbers is required every 18 months, which means that testing can be performed during refueling outages for most of the snubbers. Functional testing could also be performed when maintenance is being done on equipment in order to reduce the time when safety-related systems are unavailable.
In this manner, through the use of accurate and proper administrative controls, functional testing of the snubbers can be accomplished without violating the existing Technical Specifications.
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s LCA 73 Page 7 of 7 Effect on FSAR Hydraulic suppressors are discussed in FSAR Sections 5.5.14.1.7 and 5.5.14.6.
Mechanical snubbers are not discussed in the FSAR.
The proposed change upgrades the surveillance inspection and testing of snubbers and therefore will increase the confidence level that snubbers on safety-related systems will perform as required to restrain movement during earthquakes, pipe ruptures, and other accident loadings, and still allow normal movements due to thermal expansion. This will be offset slightly due to the fact that portions of safety-related systems will be inoperable during functional testing of the snubbers. However, the proposed change will not introduce any new accidents or affect the results or consequences of any previously analyzed transients. Therefore, no change to the FSAR is required.
Environmental Effect The proposed change will not affect the environmental analyses presented in the FSAR, the environmental report, or the final environmental statement.
No unreviewed environmental matter exists, and there will be no significant impact on the environment from this change.
SCHEDULE CONSIDERATIONS The inspections will begin during a refueling outage.
As such, approval of this LCA is requested at least 30 days prior to the start of the outage.
BASIS FOR DETERMINATION OF AMENDMENT CLASS This LCA has been determined to result in a Class III amendment in accordance with 10 CFR 170.22.
This LCA involves a single issue and does not involve a significant hazards consideration.
The fee for a Class III amendment is $4,000.
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