ML063620435
| ML063620435 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry, Watts Bar, Sequoyah, Bellefonte  |
| Issue date: | 12/22/2006 |
| From: | Wetzel B Tennessee Valley Authority |
| To: | NRC/ADM/DAS/RDB |
| References | |
| 71FR55517 00046, DG-1172 | |
| Download: ML063620435 (11) | |
Text
-u 2
ýJ C:ý., C-_
) j- I
~1 Tennessee Valley Authority, 1101 Market Street, Chattanooga, Tennessee 37402-2801 19 Cf.)
December 22, 2006
///~ &6&27 Rules and Directives Branch Office of Administration U.S. Nuclear Regulatory Commission Washington, D.C. 20555-0001 (MS T-6 D59)
Gentlemen:
TENNESSEE VALLEY AUTHORITY (TVA) - COMMENTS ON DRAFT REGULATORY GUIDE DG -1172, "APPLICATION AND TESTING OF SAFETY-RELATED DIESEL GENERATORS IN NUCLEAR POWER PLANTS" (VOL. 71 FR 55517-55520)
This letter provides TVA's comments on the subject draft Regulatory Guide.
The TVA individual providing these comments, Mr. Tim Chan, is the Chairman of the Engine Systems Inc. Electro-Motive Diesel (ESI-EMD) Owners Group Regulatory Subcommittee. The ESI-EMD Owners Group is the largest emergency diesel generator Owners Group, representing over 30 U.S. nuclear plants.
The enclosed comments should therefore be considered to be the ESI-EMD Owners Group and TVA's comments.
TVA appreciates the opportunity to comment on the proposed guidance. If you have questions regarding our comments, please contact Fred Mashburn at (423) 751-8817.
Sincerely, Beth A. Wetzel a4tz-Manager, Corporate Licensing and Industry Affairs 7~~f- - ,9) cc: See page 2
- 2. C5&(14 printedon recycled paper
U.S. Nuclear Regulatory Commission Page 2 December 22, 2006 Enclosure cc (Enclosure):
U.S. Nuclear Regulatory Commission Attn: Document Control Desk One White Flint North 11555 Rockville Pike Rockville, Maryland 20852-2738
Enclosure DG-1172: RG 1.9, Revision 4 (Draft)
Comments from ESI-EMD Owners Group Attachment 1 - RG and SRP Review Form Document Name/Number: Reviewer Name/Affiliation Tim Chan / ESI-EMD Owners Group Regulatory Subcommittee; TVA Date: December 15, 2006 Section Priority Regulatory Basis Description of the Issue Proposed Alternate (Hi, Med, Low)
C.X.Y.n.m 1, 2 or 3 Cite NRC's regulatory basis, if Description of the issue: why Mark-up text or alternate wording, where any (e.g., 10 CFR 50.xxx, NRC this is an issue; reasons for possible Bulletin 98-xx, etc.). Basis for inability of current plants to comments on inadequacy comply, if any B.lst pp (2) 3 "(2) provide power promptly to Need to clarify here if a LOOP is Possibly add Design Basis Event to definitions in engineered safety features if a loss of considered a design basis event. Section C.
offsite power and a design-basis event occur during the same time
____________period, and..."
B.7 th pp 2 "However, the design-basis event A numerical value for margin should Add 5% margin loads during the operating license or be specified. A 5% margin is certainly combined license stages should be adequate given that virtually all diesels within the continuous rating of the can exceed continuous ratings for a emergency diesel generators with period of time.
margin." _________________________
Document Name/Number: Reviewer Name/Affiliation Tim Chan / ESI-EMD Owners Group Regulatory Subcommittee; TVA Date: December 15, 2006 Section Priority Regulatory Basis Description of the Issue Proposed Alternate (Hi, Med, Low) ________________
C.1.3 2 "During the operating license or A numerical value for margin should Add 5% margin combined license stages of review, be specified. A 5% margin is certainly the design-basis event loads should adequate given that virtually all diesels be within the continuous rating (as can exceed continuous ratings for a defined in Section 3.2 of IEEE Std. period of time.
387-1995) of the diesel generator with margin."
C.1.4 2 This clause provides specific details Ideally, minimum voltage readings Add a sentence stating that voltage and frequency regarding "the starting and load- should be specified at motor data should be collected at the diesel output accepting capabilities terminals, however, data collection is breaker.
of the diesel generator.", significantly more difficult.
Consequently, reasonable and conservative numbers should be specified for voltage at the diesel output breaker. The location where voltage and frequency data is collected should be specified.
C.1.5 2 "The design should allow testing of Regarding "environments (e.g., Delete and environments (e.g., temperature, the diesel generators to simulate the temperature, humidity): Sites humidity)" or better explain that this clause is not parameters of operation (e.g., manual currently have no capability to control intended to have sites control DG room start, automatic start, load the environment - outside temperature temperature and humidity for testing.
sequencing, load shedding, operation and/or humidity - for current testing.
time), normal standby conditions, and For future plants controlling these environments (e.g., temperature, parameters would be very cost humidity) that would be expected if prohibitive to test at these extremes.
actual demand were placed on the Testing from normal standby
_____________________system." conditions is appropriate
Document Name/Number: Reviewer Name/Affiliation Tim Chan / ESI-EMD Owners Group Regulatory Subcommittee; TVA Date: December 15, 2006 Section Priority Regulatory Basis Description of the Issue Proposed Alternate (Hi, Med, Low)______________ _
C.1.9.2 2 "(2) A trip may be bypassed under This section implies trips should not IEEE Std. 387-1995, Section 4.5.4 a and b design-basis events, provided the be bypassed if operators cannot react language is sufficient. Eliminate clause on operator has sufficient time to react in sufficient time. Under DBE operator.
appropriately to an abnormal diesel conditions, operator response time generator condition."ý cannot be assured as operators are not normally present initially or continuously at the EDG during an event. We are of the opinion that trips other than overspeed and generator differential should be bypassed during design basis events due to the possibility of a spurious trip. In addition, this reduces the complexity of the control scheme in the emergency mode.
C.1.8-p.7 3 "11.8 Clause 4.5.2.2 of IEEE Std. The section is numbered 1.8 - it Clerical fix.
387-1995 should be modified to read should be numbered 1.10 as follows:"
C.2.1 2 "component malfunctions or The term "within a few minutes" is too Change within a few minutes to 30 minutes operating errors that did not prevent vague and allows the emergency diesel generator from for inconsistent interpretation both being restarted and brought to load from the licensee and the regulator. A within a few minutes (i.e., without numerical value such as 30 minutes corrective maintenance or significant should be selected.
problem diagnosis)"______________________
C.2.2 2 "Test Descriptions... .The following This section of the document is very Please improve section by 1) Having separate test descriptions should be used in confusing for the following reasons: sections for site acceptance tests and Availability conjunction with the preoperational 1) The section lists only 11 tests, tests; 2) Provide brief descriptions (even if and surveillance testing described in though 21 are listed in Table 1; 2) repeated from IEEE) for all required tests.
the table." Many tests do not have a description, with most simply notes where the IEEE guidance should be supplemented; 3) Site acceptance tests
____________________________are
________________________ mixed in with availability tests.
Document Name/Number: Reviewer Name/Affiliation Tim Chan / ESI-EMD Owners Group Regulatory Subcommittee; TVA Date: December 15, 2006 Section Priority Regulatory Basis Description of the Issue Proposed Alternate (Hi, Med, Low)
Some examples of confusion are 1)
Starting test (a site acceptance test) as 2.2.1 with Stow Start test as 2.2.2.,
and 2) Load Run (load acceptance)
Test as 2.2.3, and Rated Load Test as 2.2.4: Though these tests are similar, having them together with very vague descriptions makes the document confusing.
C.2.2 2 Table 1 Table 1 is very confusing for the Please improve section as follows: 1) Have following reasons: separate test description sections for each of tests
- 1) All tests are not present in the Test listed, and 2) Refer back to IEEE guidance to Description portion of the document, complete Table.
and 2) The Table seems to be incomplete with no boxes checked for Availability tests.__________________________
Document Name/Number: Reviewer Name/Affiliation Tim Chan / ESI-EMD Owners Group Regulatory Subcommittee; TVA Date: December 15, 2006 Section
__________ 1 I(Hi, Priority Med, o )
Regulatory Basis Description of the Issue
_____________________Low)_____________________________
Proposed Alternate C.2.2.3 1 "This test involves demonstrating DBE loads in excess of continuous Eliminate "...or worst case design-based event 90-100 percent of the continuous ratings are effectively not loads (whichever is higher)..."
rating or worst case design-basis permitted by C. 1.3 due to margin event loads (whichever is higher) of requirements - as such this should not the emergency diesel generator,..." apply to any plant designed after 2007.
If the site somehow does have maximum design basis loads greater than the continuous rating (typically only for a short period of time) it is recommended that the EDG not have monthly testing at overload conditions.
This is potentially destructive testing that is expected to have a significant impact on EDG reliability over time.
Testing at the continuous rating monthly should be sufficient to verify successful performance of the EDG -
meeting DBE loading can be satisfactorily verified during part of the endurance run performed every 18-24 months. This is a significant equipment issue that has not been recommended by IEEE.
Document Name/Number: Reviewer Name/Affiliation Tim Chan / ESI-EMD Owners Group Regulatory Subcommittee; TVA Date: December 15, 2006 Section Priority Regulatory Basis Description of the Issue Proposed Alternate (Hi, Med, Low)
C.2.2.4 1 "If the design-basis event loads are DBE loads in excess of continuous Eliminate clause.
higher than the continuous rating of ratings are effectively not the emergency diesel generator, the permitted by C.1.3 due to margin test should be conducted at the worst requirements - as such this should not case design-basis event loads..." apply to any plant designed after 2007; If the site somehow does have maximum design basis loads greater than the continuous rating (typically only for a short period of time) it is recommended that the EDG not have monthly testing at overload conditions.
This is potentially destructive testing that is expected to have a significant impact on EDG reliability over time.
Testing at the continuous rating monthly should be sufficient to verify successful performance of the EDG -
meeting DBE loading can be satisfactorily *vrified during part of the endurance run performed every 18-24 months. This is a significant equipment issue that has not been recommended by IEEE.
C.2.2.6 2 "Combined Safety Injection It is our understanding that the NRC is It is suggested that the NRC review their current Actuation System (SIAS) and Loss- in conversation with the BWR Owners position on separation of LOOP and LOCA Of-Offsite Power Test" Group regarding the separation of the design basis events and ensure that the testing LOOP and LOCA design basis events, required in this document (i.e., the Combined If this is indeed the case, this test may SIAS / LOOP Test) is consistent with the NRC no longer be necessary. position.
Document Name/Number: Reviewer Name/Affiliation Tim Chan / ESI-EMD Owners Group Regulatory Subcommittee; TVA Date: December 15, 2006 Section Priority Regulatory Basis Description of the Issue Proposed Alternate (Hi, Med,
_________ Low)_________ ______
C.2.2.7 1 "This test involves demonstrating the Testing "while operating at the largest Eliminate ". . .while operating at largest load emergency diesel generator's load power factor" is a potentially power factor..."
capability to reject a load equal to destructive test. When paralleled to loss of the largest single load while the grid, the voltage is artificially operating at largest load power factor offset high to allow rated kvar and verify that the frequency and loading. Upon load rejection, the voltage requirements are met and the accompanying voltage spike can unit will not trip on overspeed." potentially exceed max vendor recommended voltage (based on the how large the load is). Recommend performing this test at 1.0 power factor and placing limits on maximum voltage seen (overshoot no greater than 15% and/or within 10% in 2
______________seconds).
C.2.2.8 1 "This test involves demonstrating the Testing "at the worst case design load Eliminate ".....while operating at worst case design emergency diesel generator's power factor" is a potentially load power factor..."
capability to reject a load equal to destructive test. When paralleled to 90-100 percent of the continuous the grid, the voltage is artificially rating while operating at a worst case offset high to allow rated kvar design load power factor and verify loading. Upon load rejection, the that the voltage requirements are met accompanying voltage spike will and that the unit will not trip on typically exceed max vendor overspeed." reconmiended voltage. Recommend performing this test at 1.0 power factor and placing limits on maximum voltage seen (overshoot no greater than 15% and/or within 10% in 2
____________________________ seconds).
Document Name/Number: Reviewer Name/Affiliation Tim Chan / ESI-EMD Owners Group Regulatory Subcommittee; TVA Date: December 15, 2006 Section Priority Regulatory Basis Description of the Issue Proposed Alternate (Hi, Med, Low)
C.2.2.9 1 "This test involves demonstrating the The 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> endurance run is contrary Change clause to reflect an 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> endurance run.
full load-carrying capability at a to the IEEE-387 (1995) worst case design load power factor recommendation (Section 7.5.9) that for an interval of not less than 24 the endurance run be completed in hours." eight hours - two hours at load equivalent to the short term rating (110% of continuous), and six hours equivalent to 90- 100% of the continuous rating. On the pre-op test the endurance run is still recommended to be a 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> run, but it recommends that the 18-24 month periodic endurance run be performed for only a total of eight hours.
Accordingly, there is no regulatory basis for a 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> run. Some plants have recently had their Technical Specification approved to operate in this manner (8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> endurance run).
C.2.2.10 1 "This test involves demonstrating the This test should not be contingent on Eliminate the clause ". .. or design-basis event hot restart functional capability at full operating the EDG for two hours at loads whichever is higher."
load-temperature conditions (after the "design basis loads (whichever is emergency diesel generator has higher). As noted previously, EDG operated for 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> at continuous or loads for new plants should not exceed design-basis the continuous rating, and if they did, event loads whichever is higher)." the EDG should not be routinely testing at loads exceeding the continuous rating. Performing this test after two hours of operation at the EDG's continuous rating is sufficient enough to meet the objective of this
_________________ ~~~~~~~~~test.__________________________
Document Name/Number: Reviewer Name/Affiliation Tim Chan / ESI-EMD Owners Group Regulatory Subcommittee; TVA Date: December 15, 2006 Section Priority Regulatory Basis Description of the Issue Proposed Alternate (Hi, Med, Low)
C.2.2.11 1 ". ..This test should also verify that It is not recommended that the critical Eliminate this clause.
the critical protective trips that are protective trips that are not bypassed not automatically bypassed perform are tested to perform their intended their intended function..." function during this test. The function of these trips can be verified in pre-start tests, relay tests, or with simulation per the site's existing maintenance program. The intent of the test is to verify that the bypassed trips do not trip the EDG during a design basis accident. This is not recommended in EEEE-387 and has no regulatory basis.
General 1 There currently exist several different It is recommended the NRC review this document protocols and regulations regarding against MSPI guidance and Improved Technical EDG performance including Specifications to ensure this guidance is Maintenance Rule, mitigating system consistent.
performance indicators (MSPI), and INPO requirements. Has the NRC performed a review to ensure this guidance is consistent with other documents, specifically MSPI and Improved Technical Specifications?
General 2 The vast majority of "should" statements should be "shall" statements. This reduces ambiguity between the licensee and the regulator. This draft Regulatory Guide is really only appropriate for plants that haven't been built yet.
Consequently, "shall" statements clearly define the design requirements as well as the test requirements. ________________________