TSTF-10-18, Response to NRC Request for Additional Information on TSTF-508, Revision 1, Revise Control Room Habitability Actions to Address Lessons Learned from TSTF-448 Implementation
| ML102850220 | |
| Person / Time | |
|---|---|
| Site: | Technical Specifications Task Force |
| Issue date: | 10/11/2010 |
| From: | Browning R, Croft W, Raidy T, Schrader K PWR Owners Group, Technical Specifications Task Force, B & W Owners Group, Combustion Engineering, Westinghouse |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| TSTF-10-18, TSTF-508, Rev 1 | |
| Download: ML102850220 (9) | |
Text
TECHNICAL SPECIFICATIONS TASK FORCE TSTF A JOINT OWNERS GROUP ACTIVITY October 11, 2010 TSTF-10-18 PROJ0753 Attn: Document Control Desk U. S. Nuclear Regulatory Commission Washington, DC 20555-0001
SUBJECT:
Response to NRC Request for Additional Information on TSTF-508, Revision 1, "Revise Control Room Habitability Actions to Address Lessons Learned from TSTF-448 Implementation"
REFERENCE:
Electronic message from B. Miller (NRC) to B. Mann (TSTF), "TSTF-508 Questions/Comments," dated July 12, 2010.
Dear Sir or Madam:
The Notice for Comment for TSTF-508, Revision 1, "Revise Control Room Habitability Actions to Address Lessons Learned from TSTF-448," was published in the Federal Register on October 15, 2009. The TSTF provided comments by letter on November 16, 2009.
On July 12, 2010, the NRC provided to the TSTF a Request for Additional Information (RAI) on TSTF-508 in the referenced electronic message.
At a public meeting between the NRC and the TSTF held on July 15, 2010, the TSTF agreed to respond to the NRC RAI without it being formally transmitted to the TSTF. The attachment provides our response.
Should you have any questions, please do not hesitate to contact us.
Kenneth J. Schrader (PWROG/W) Roy A. Browning (BWROG)
Thomas W. Raidy (PWROG/CE) Wendy E. Croft (PWROG/B&W)
Attachment cc: Robert Elliott, Technical Specifications Branch, NRC Barry Miller, Licensing Processes Branch, NRC 11921 Rockville Pike, Suite 100, Rockville, MD 20852 Phone: 301-984-4400, Fax: 301-984-7600 Administration by EXCEL Services Corporation
Response to NRC Request for Additional Information on TSTF-508, Revision 1, "Revise Control Room Habitability Actions to Address Lessons Learned from TSTF-448 Implementation," Dated July 12, 2010
RAI 1
Per TSTF-508, Rev. 1, "Required Action B.2 states, 'Verify mitigating actions ensure CRE occupant exposures to radiological, chemical, and smoke hazards will not exceed limits.' This wording is incorrect in that it refers to limits for chemical and smoke hazards but these hazards do not have quantifiable limits. The Required Action is revised to state, 'Verify mitigating actions ensure CRE occupant radiological exposures will not exceed limits, and CRE occupants are protected from chemical and smoke hazards.' "
The statement that there are no quantifiable limits is not entirely correct. Regulatory Guides provide methods acceptable to the NRC staff for meeting the regulations. In this case Regulatory Guide (RG) 1.78, "Evaluating the Habitability of a Nuclear Power Plant Control Room During a Postulated Hazardous Chemical Release," provides toxicity limits for meeting General Design Criterion 19 which is the basis for 3.7.10, "Control Room Emergency Ventilation System (CREVS)." How was this change justified in the Traveler given that there are chemical limits provided in RG 1.78?
Response
TSTF-508 corrects and extends the changes in TSTF-448, Revision 3, "Control Room Habitability," which was approved by the NRC on January 17, 2007. The NRC Safety Evaluation for TSTF-448 was published in the Federal Register on January 17, 2007. As stated in the TSTF-508 justification, the proposed change to Condition B revises the wording of the Required Action to be consistent with the Safety Evaluation, which states:
"New Action B would allow 90 days to restore the [Control Room Envelope] CRE boundary (and consequently, the affected [CREEVS] [trains]) to operable status, provided that mitigating actions are immediately implemented and within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> are verified to ensure, that in the event of a DBA, CRE occupant radiological exposures will not exceed the calculated dose of the licensing basis analyses of DBA consequences, and that CRE occupants are protected from hazardous chemicals and smoke." (emphasis added)
This characterization of quantitative limits on dose and non-quantitative protection from hazardous chemicals and smoke appears throughout the Safety Evaluation.
The description of non-quantitative limits on chemicals is appropriate as the licensing basis for most licensees does not contain quantitative limits on chemicals. RG 1.78, Revision 0, does not require an analysis of chemical hazards unless chemicals are present in sufficient quantities that the control room may become inhabitable. The Regulatory Position provided in RG 1.78 states:
"If major depots or storage tanks of hazardous chemicals such as the chemicals listed in Table C-1 of this guide are known or projected to be present within a five-mile radius of the reactor facility, these chemicals should be considered in the evaluation of control room habitability. ... Chemicals stored or situated at distances greater than five miles from the facility need not be considered."
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Response to NRC Request for Additional Information on TSTF-508, Revision 1, "Revise Control Room Habitability Actions to Address Lessons Learned from TSTF-448 Implementation," Dated July 12, 2010 It goes on further to state:
"If hazardous chemicals such as those indicated in Table C-1 are known or projected to be frequently shipped by rail, water, or road routes within a five mile radius of a nuclear power plant, estimates of these shipments should be considered in the evaluation of control room habitability. ... If the quantity, per shipment, of hazardous chemicals frequently shipped past a site is less than the adjusted quantity shown in Table C-2 for the control room type being evaluated, the shipments need not be considered in the analysis."
Most licensees demonstrated that the chemical hazards are not present in the quantities and within the distances described in RG 1.78 and, therefore, no specific analysis was required.
Should a licensee enter Condition B of the subject specification, verification that the operators are protected from chemical hazards consists of ensuring that the UFSAR evaluation remains applicable (e.g., that the types, quantities and location of chemicals is consistent with the licensing basis). This verification would not include any consideration of increased control room inleakage while in the Condition. As a result, the TSTF-448 Required Action statement, "Verify mitigating actions ensure CRE occupant exposures to radiological, chemical, and smoke hazards will not exceed limits," is inconsistent with the licensing basis, as there are no specific limits on control room chemical concentrations that would be affected by the inoperable CRE boundary and the mitigating actions will have no effect on the licensing basis evaluation of operator protection from chemicals. Several licensees have already revised the wording in Condition B to match the proposed change in TSTF-508 during their adoption of TSTF-448, to be consistent with their licensing basis.
For those plants with a licensing basis that includes explicit analysis of chemical hazards, including assumptions on control room inleakage, the proposed Required Action in TSTF-508 is still appropriate. The TSTF-508 Required Action states, "Verify mitigating actions ensure CRE occupant radiological exposures will not exceed limits, and CRE occupants are protected from chemical and smoke hazards." For those plants with a chemical hazard analysis, the Required Action requires verifying that the chemical hazard does not exceed the quantitative limits in the analysis in order to confirm the CRE occupants are protected.
RAI 2
The extension of the use of mitigating actions to Modes 5 and 6 to restore the boundary to operable status does not seem adequately justified or warranted.
LCO 3.7.10 is unique in that it allows for a complete loss of control room boundary integrity, as defined in the design basis, and allows for undefined mitigative actions to restore the boundary to operable status. This is instead of the traditional required actions of "suspending fuel movement" or "shutting down the reactor."
When "One or more CREVS trains inoperable due to inoperable CRE boundary," this change would (a) enable meeting the LCO despite significant degradation of the CRE boundary, (b) permanently incorporate use of mitigating actions into the facility licensing basis to support CRE boundary operability, and (c) serve as a disincentive to maintain the CRE boundary in its design Page 2
Response to NRC Request for Additional Information on TSTF-508, Revision 1, "Revise Control Room Habitability Actions to Address Lessons Learned from TSTF-448 Implementation," Dated July 12, 2010 condition, and consequently weaken the effectiveness of the proposed CRE habitability administrative controls program specification.
While this is currently allowed for Modes 1-4, extension to Modes 5 and 6 may not be warranted. In the current specification an exception was made for Modes 1-4. The traditional NRC position is that while we accept (footnote 1) the use of compensatory measures "to restore inoperable structures, systems, or components (SSCs) to an operable but degraded or nonconforming status," we do not accept (footnote 2) for this purpose the use of measures that "do not support the capability of an SSC to perform its specified safety function consistent with the current licensing and design basis acceptance criteria."
A special exception to this position was made for Modes 1-4. The risk of shutdown could be greater than the risk of continued operations with a control room that did not meet its design basis, but by use of mitigating actions, could be shown to not "exceed limits." This is not the case with Modes 5 and 6. Despite the argument presented, the risk of suspending fuel movement is likely much smaller than the risk associated with the use of unspecified and seldom used mitigating actions such as potassium iodide or a self contained breathing apparatus.
As a follow-on question, why werent specific compensatory measures or mitigating actions identified?
Footnote 1 NRC Regulatory Issue Summary 2005-20: Revision to Guidance Formerly Contained in NRC Generic Letter 91-18, "Information to Licensees Regarding Two NRC Inspection Manual Sections On Resolution of Degraded and Nonconforming Conditions and On Operability,"
September 26, 2005, Section 7.3, "Compensatory Measures." (ADAMS Accession No. ML052020424.).
Footnote 2 NRC letter dated January 30, 2004, from E. J. Leeds, NRC, to J. W. Davis, NEI, page 4 (ADAMS Accession No. ML040300694.)
Response
The question is based on an incorrect understanding of the Technical Specifications requirements approved by the NRC in TSTF-448 and the Technical Specifications rules of usage.
- The RAI states, "LCO 3.7.10 is unique in that it allows for a complete loss of control room boundary integrity, as defined in the design basis, and allows for undefined mitigative actions to restore the boundary to operable status." This is incorrect. LCO 3.7.10 (and the corresponding LCO in the other Improved Standard Technical Specification NUREGs) is not met when control room boundary inleakage is greater than that assumed in the licensing basis analyses, in accordance with LCO 3.0.2:
"Upon discovery of a failure to meet an LCO, the Required Actions of the associated Conditions shall be met, except as provided in LCO 3.0.5 and LCO 3.0.6."
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Response to NRC Request for Additional Information on TSTF-508, Revision 1, "Revise Control Room Habitability Actions to Address Lessons Learned from TSTF-448 Implementation," Dated July 12, 2010 As stated in the SR 3.7.10.4 Bases:
"When unfiltered air inleakage is greater than the assumed flow rate, Condition B must be entered. Required Action B.3 allows time to restore the CRE boundary to OPERABLE status provided mitigating actions can ensure that the CRE remains within the licensing basis habitability limits for the occupants following an accident.
Compensatory measures are discussed in Regulatory Guide 1.196, Section C.2.7.3, (Ref.
- 5) which endorses, with exceptions, NEI 99-03, Section 8.4 and Appendix F (Ref. 6).
These compensatory measures may also be used as mitigating actions as required by Required Action B.2." (emphasis added)
As stated, Required Action B.3 provides time to restore Operability provided the compensatory measures in Required Action B.2 are satisfied. If not, then Condition C is entered. These compensatory measures do not restore Operability.
- The RAI states, "When 'One or more CREVS trains inoperable due to inoperable CRE boundary,' this change would (a) enable meeting the LCO despite significant degradation of the CRE boundary, (b) permanently incorporate use of mitigating actions into the facility licensing basis to support CRE boundary operability, and (c) serve as a disincentive to maintain the CRE boundary in its design condition, and consequently weaken the effectiveness of the proposed CRE habitability administrative controls program specification."
o As explained above, Condition B is entered when the LCO is not met and, by definition, being in Condition B means the LCO is not met. The only Required Action in Condition B that restores compliance with the LCO is Required Action B.3, "Restore CRE boundary to OPERABLE status."
o The Condition does not "permanently incorporate use of mitigating actions into the facility licensing basis to support CRE boundary operability." Taking mitigating actions does not restore the CRE boundary to operable status.
o The Condition does not "serve as a disincentive to maintain the CRE boundary in its design condition." The Technical Specification Control Room Habitability Program states:
"A Control Room Envelope (CRE) Habitability Program shall be established and implemented to ensure that CRE habitability is maintained such that, with an OPERABLE Control Room Emergency Filtration System (CREFS), CRE occupants can control the reactor safely under normal conditions and maintain it in a safe condition following a radiological event, hazardous chemical release, or a smoke challenge,"
and specifically requires:
"maintaining the CRE boundary in its design condition including configuration control and preventive maintenance." (emphasis added)
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Response to NRC Request for Additional Information on TSTF-508, Revision 1, "Revise Control Room Habitability Actions to Address Lessons Learned from TSTF-448 Implementation," Dated July 12, 2010 The Required Actions for an inoperable boundary do not modify or undermine the requirement for the boundary to be Operable.
- The Condition does not allow the use of compensatory measures "to restore inoperable structures, systems, or components (SSCs) to an operable but degraded or nonconforming status." The mitigating actions in Condition B do not restore the system CRE boundary to Operable status, as explained above. These changes were made in TSTF-448 to specifically address Staff concerns similar to those expressed in this RAI. TSTF-508 makes no changes to these Required Actions. From TSTF-448, Rev 3:
"On December 28, 2005, the NRC provided a letter to the TSTF with their comments on TSTF-448, Revision 2 (Reference 11). In the letter, the NRC stated that they disagreed with many of the approaches taken in TSTF-448, Revision 2. In particular, the NRC did not agree with approach of considering the CRE degraded but operable if CRE inleakage exceeds the inleakage assumed in the accident analysis, even if the control room operators can be protected with mitigating actions." {emphasis added}
- The RAI states, "A special exception to this position was made for Modes 1-4. The risk of shutdown could be greater than the risk of continued operations with a control room that did not meet its design basis, but by use of mitigating actions, could be shown to not 'exceed limits'." This was not the basis of the approval for Condition B in TSTF-448. As stated in the Safety Evaluation for TSTF-448:
"The 90-day Completion Time of new Required Action B.3 is reasonable based on the determination that the mitigating actions will ensure protection of CRE occupants within analyzed limits while limiting the probability that CRE occupants will have to implement protective measures that may adversely affect their ability to control the reactor and maintain it in a safe shutdown condition in the event of a DBA. The 90-day Completion Time is a reasonable time to diagnose, plan and possibly repair, and test most anticipated problems with the CRE boundary. Therefore, proposed Action B is acceptable."
Relative risk of continued operation versus shutdown was not a cited factor in the NRC previous determination o f acceptability.
- The RAI asks, "Why werent specific compensatory measures or mitigating actions identified?" Prior to TSTF-448, in order to adopt a 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> Completion Time for an inoperable boundary, licensees were required to make a commitment to have written procedures describing compensatory measures to be taken. In TSTF-448, the industry proposed placing the requirement to take mitigating actions directly into the Technical Specifications. The Bases state:
"These mitigating actions (i.e., actions that are taken to offset the consequences of the inoperable CRE boundary) should be preplanned for implementation upon entry into the condition, regardless of whether entry is intentional or unintentional."
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Response to NRC Request for Additional Information on TSTF-508, Revision 1, "Revise Control Room Habitability Actions to Address Lessons Learned from TSTF-448 Implementation," Dated July 12, 2010 To attempt to adequately list every potential mitigating action that may be appropriate to respond to an inoperable CRE boundary would be problematic. Therefore, the Bases reference Regulatory Guide 1.196. The Bases for SR 3.7.10.4 state:
"Compensatory measures are discussed in Regulatory Guide 1.196, Section C.2.7.3, (Ref.
- 7) which endorses, with exceptions, NEI 99-03, Section 8.4 and Appendix F (Ref. 8).
These compensatory measures may also be used as mitigating actions as required by Required Action B.2."
Note that all of the statements discussed above are related to the Technical Specification changes previously approved by the NRC in TSTF-448 and are not proposed to be changed by TSTF-508.
- The RAI states, "Despite the argument presented, the risk of suspending fuel movement is likely much smaller than the risk associated with the use of unspecified and seldom used mitigating actions such as potassium iodide or a self contained breathing apparatus." Such a risk-based argument was not part of the justification used to support the change in TSTF-508.
As stated in the TSTF-508 justification:
"The current action, which requires the immediate suspension of movement of [recently]
irradiated fuel assemblies when the CRE boundary is inoperable, is an overly restrictive and unnecessary action. First, suspension of fuel movement is unnecessary once Required Action B.2 verifies that the required mitigating actions protect the CRE occupants. Second, the proposed change is more restrictive in that the existing action to suspend [recently] irradiated fuel assemblies does nothing to mitigate the effects of a chemical or smoke hazard. Third, suspension of fuel movement until the CRE boundary is restored to Operable status can disrupt a carefully planned refueling schedule and increases the risk of a human performance error. If the Required Actions of Condition B cannot be met (i.e., if cannot be verified that the mitigating actions ensure CRE occupants are protected from radiological, chemical, and smoke hazards) the existing action to suspend movement of [recently] irradiated fuel assemblies applies. This parallels the Actions for the operating Modes. Therefore, there is an improvement in the protection provided by the Required Actions while providing additional flexibility and reducing the possibility of human performance errors."
In addition, in response to earlier Staff comments on TSTF-508, Rev. 0, a new Required Action and a Note were added in Revision 1 to Condition B to specifically require suspension of movement of [recently] irradiated fuel until such time as the compensatory measures in Required Action B.3 are verified. Only then, can fuel movements resume with CRE boundary inleakage above limits.
RAI 3
TSTF-508, Rev. 1 states: "The Control Room Envelope Habitability Program, paragraph d, requires pressure testing at a Frequency of [18] months on a STAGGERED TEST BASIS. The last sentence of the paragraph states, 'The results shall be trended and used as part of the [18]
month assessment of the CRE boundary.' This statement is incorrect as the assessment being referenced is required by Regulatory Guide 1.197 to be performed every 36 months, not every 18 Page 6
Response to NRC Request for Additional Information on TSTF-508, Revision 1, "Revise Control Room Habitability Actions to Address Lessons Learned from TSTF-448 Implementation," Dated July 12, 2010 months. This error was identified shortly before the final approval of TSTF-448 and acknowledged by the NRC and the industry. The sentence is revised to state, 'The results shall be trended and used as part of the periodic assessment of the CRE boundary.' "
The current 3.7.10 uses an SR to verify operability every 18 months by using a delta p test. This is one of a multi-pronged approach to ensure habitability. The tracer gas test is only performed every 6 to 7.5 years. Shouldnt the assessment be performed every 18 months (following the delta p test) since it propagates what was previously done and is necessary to verify habitability between tracer gas tests? With this change licensees will no longer be required to assess the results every 18 months since the new "periodic" assessment that is referred to in the change is on a 36 month basis. Is this the intent of the change, or is there another interpretation? Is the justification based purely on RG 1.197?
Response
The RAI statement, "The current 3.7.10 uses an SR to verify operability every 18 months by using a delta p test," is incorrect. TSTF-448 deleted SR 3.7.10.4 and removed the differential pressure test from Operability considerations based on NRC's Generic Letter 2003-01, which concluded that the differential pressure surveillance is not a reliable method for demonstrating control room envelope integrity, i.e., Operability.
As stated in the justification for TSTF-448:
"[A]s pointed out in Generic Letter 2003-01, the usefulness of differential pressure measurements is very limited and the importance of data from these measurements should not be overemphasized. Therefore, the Control Room Envelope Habitability Program requires measuring differential pressure every [18] months on a STAGGERED TEST BASIS in a manner similar to the current requirement in the Technical Specifications. The results will be trended and compared to positive pressure measurements taken, or to be taken, during CRE inleakage testing. These evaluations will be used as part of an assessment of CRE boundary integrity between CRE boundary inleakage tests. This approach balances the desire to assess CRE habitability between the performance of inleakage tests with the complexities inherent in the interpretation of differential pressure measurements." (emphasis added)
During the development of TSTF-448, Revision 3, TS 5.5.[18] "Control Room Envelope Habitability Program," paragraph d was reworded in a manner that unintentionally applied the
[18] month Frequency to both the performance and assessment of the delta-p test. The intention was that the test be performed every [18] months and the trending and comparison be evaluated as part of the 36 month assessment required by Regulatory Guide 1.197 in 5.5.[18] paragraph c, item (ii): "(ii) assessing CRE habitability at the Frequencies specified in Sections C.1 and C.2 of Regulatory Guide 1.197, Revision 0." Previous versions of TSTF-448 had stated:
"The results shall be trended and compared to the positive pressure measurements taken or to be taken during control room inleakage testing. These evaluations shall be used as part of an assessment of control room boundary integrity between control room inleakage tests." [Note that no frequency is specified.]
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Response to NRC Request for Additional Information on TSTF-508, Revision 1, "Revise Control Room Habitability Actions to Address Lessons Learned from TSTF-448 Implementation," Dated July 12, 2010 Thus, the proposed change in TSTF-508 merely corrects an inadvertent change made during the final revision of TSTF-448.
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