ML102910618
| ML102910618 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse, Indian Point  |
| Issue date: | 10/14/2010 |
| From: | Conte R Division of Nuclear Materials Safety I |
| To: | Conte R Division of Nuclear Materials Safety I |
| References | |
| Download: ML102910618 (4) | |
Text
October 14, 2010 MEMORANDUM TO: File FROM: Richard J. Conte, Chief /RA/
Engineering Branch 1 Division of Reactor Safety Region I
SUBJECT:
Documentation of Telephone Conversation Between Mr. David Lochbaum Regarding Follow-up Questions Related To NRC Letter Dated July 28, 2010 (ML102040807)
The purpose of this memorandum is to document a summary response to the subject follow-up questions from Mr. David Lochbaum, Union of Concerned Scientists, to Mr. Richard Barkley, shortly after the July 28, 2010, letter was issued. The summary response was communicated by NRC staff verbally on September 3, 2010 (enclosed). In attendance on the call were Mr.
Lochbaum and Messrs. Richard Conte, Mel Gray, and Richard Barkley of the NRC staff. There were no outstanding questions as a result of the conversation.
Mr. Lockbaums letter dated June 23, 2010, expressed views regarding a refueling cavity leak at Indian Point Unit 2, described in a recent NRC inspection report, and potential correlation to operating experience related to the Davis-Besse reactor vessel head. The NRCs response letter of July 28, 2010, indicated that the underlying conditions at Indian Point Unit 2 were not the same as those that led to the reactor vessel degradation at Davis-Besse. While NRCs review of Indian Point Unit 2 continued, the NRC staff had not identified any safety significant impacts resulting from this periodic leakage. Notwithstanding these conditions and as a part of the agencys oversight role, we expected the licensee to continue to pursue appropriate actions to identify, remediate, and permanently correct the source of the leak.
Enclosure:
As stated cc:
W. Dean, ORA, RI M. Dapas, ORA, RI D. Roberts, DRS, RI J. Clifford, DRP, RI N. Salgado, NRR G. Matakas, ORA, RI D. Bearde, DRS, RI K. Heater, DRS, RI
MEMORANDUM TO: File FROM: Richard J. Conte, Chief /RA/
Engineering Branch No. 1 Division of Reactor Safety Region I
SUBJECT:
Documentation of Telephone Conversation Between Mr. David Lochbaum Regarding Follow-up Questions Related To NRC Letter Dated July 28, 2010 (ML102040807)
The purpose of this memorandum is to document a summary response to the subject follow-up questions from Mr. David Lochbaum, Union of Concerned Scientists, to Mr. Richard Barkley, shortly after the July 28, 2010, letter was issued. The summary response was communicated by NRC staff verbally on September 3, 2010 (enclosed). In attendance on the call were Mr.
Lochbaum and Messrs. Richard Conte, Mel Gray, and Richard Barkley of the NRC staff. There were no outstanding questions as a result of the conversation.
Mr. Lockbaums letter dated June 23, 2010, expressed views regarding a refueling cavity leak at Indian Point Unit 2, described in a recent NRC inspection report, and potential correlation to operating experience related to the Davis-Besse reactor vessel head. The NRCs response letter of July 28, 2010, indicated that the underlying conditions at Indian Point Unit 2 were not the same as those that led to the reactor vessel degradation at Davis-Besse. While NRCs review of Indian Point Unit 2 continued, the NRC staff had not identified any safety significant impacts resulting from this periodic leakage. Notwithstanding these conditions and as a part of the agencys oversight role, we expected the licensee to continue to pursue appropriate actions to identify, remediate, and permanently correct the source of the leak.
Enclosure:
As stated cc w/encl:
W. Dean, ORA, RI M. Dapas, ORA, RI D. Roberts, DRS, RI J. Clifford, DRP, RI N. Salgado, NRR G. Matakas, ORA, RI D. Bearde, DRS, RI K. Heater, DRS, RI SUNSI Review Complete: RJC (Reviewer=s Initials) ML102910618 DOCUMENT NAME: G:\DRS\Engineering Branch 1\___EDATs Items\EDATS10-0548(GT10-0419) IP2 Ref Cav Leakage\ucs follow up question response Final 5 EDATS 2010-0344.docx After declaring this document AAn Official Agency Record@ it will be released to the Public.
To receive a copy of this document, indicate in the box: "C" = Copy without attachment/enclosure "E" = Copy with attachment/enclosure "N" = No copy OFFICE RI/ORA RI/DRP RI/DRS RI/DRS NAME RBarkley/RB* MGray/MG* RConte/rjc DRoberts/prw for DATE 10/12/10 10/12/10 10/12/10 10/14/10
- See Previous Concurrence Page OFFICIAL RECORD COPY
Documentation of Telephone Conversation with Mr. David Lochbaum Concerning Follow-up Questions on NRC letter of July 28, 2010 Page A-1 ENCLOSURE Question 1: Containment leakage detection equipment is not required to be operable in Mode 5 and 6. If this equipment were out-of-service as allowed by Technical Specifications (TS), what would clue the workers/operators into the need to respond to this deteriorating condition? When would workers take appropriate steps to respond to the deteriorating plant condition?
Response: Containment leakage detection equipment is not required to be operable in Mode 5 and 6 since personnel are in and out of containment almost continuously, and the primary system is not pressurized. The leakage detection systems are required to be operational during reactor coolant system heat up and operational modes because the containment is normally treated as a confined space during those periods and thus infrequently visited by personnel, so leakage detection systems are needed. These systems are also needed to detect primary system leakage at the low rates prescribed by the TS when the plant is in operation.
As described in our letter response, TS [section 3.9.6 LCO/SR] require periodic verification that refueling cavity water level is at or above a specified level [>24 feet] above the top of the reactor vessel flange during fuel movement. This frequency (every 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />) is based on engineering judgment and is considered adequate in view of the large volumes of water and the procedural controls of valve positions, which make significant unplanned level changes unlikely. In addition, a licensed Senior Reactor Operator is always required to be present during core alterations to directly supervise the activity, and would observe and take action on any significant drop in cavity level in fulfilling the responsibilities of 10 CFR 50.54(m)(2)(iv). Finally, radiation monitors are required to be operable for the containment purge system by TS [section 3.3.6 LCO/SR] during irradiated fuel movement and are calibrated and set to alarm on an increase of radiation levels for any reason, one of which may be due to a sudden drop in cavity water level. Further, other area radiation monitors are to be functional on the refueling floor.
Overall, specific actions governing response to these changes in water and radiation levels are delineated in Entergys abnormal operating procedures.
Question 2: Section 9.5.1.4. of the UFSAR for IP-2 states that: The reactor cavity, refueling canal and spent fuel storage pit are reinforced concrete structures with a seam-welded stainless steel plate liner. These structures are designed to withstand the anticipated earthquake loadings as seismic Class I structures so that the liner prevents leakage even in the event the reinforced concrete develops cracks. This wasnt addressed in the NRCs letter of July 28, 2010.
Response: The NRC staff has reviewed the refueling cavity leakage issue at Indian Point Unit 2 (IP2) for some time, and has not identified any immediate safety concerns. As we noted in our July 28, 2010 letter, the refueling cavity does not serve a safety function while the plant is operating at power. The period of exposure for cavity leakage is about two weeks every two years during refueling operations. While our initial answer was primarily focused on addressing your comparisons of the IP2 situation to the Davis-Besse operating experience regarding the degraded reactor vessel head, particularly the potential for the known leakage to cause long-term cavity liner degradation due to boric acid buildup, we continue to evaluate the impact of the Enclosure
Documentation of Telephone Conversation with Mr. David Lochbaum Concerning Follow-up Questions on NRC letter of July 28, 2010 Page A-2 leakage on the liners seismic function as it is defined in IP2 licensing basis documents, including the UFSAR. The NRC has historically taken the position that some minor pre-existing liner leakage may not compromise the overall seismic function of the liner, which is to prevent a substantial coolant loss that could result in damage to fuel assemblies. As we noted in the July 28th response, the IP2 leakage rate has varied between two to ten gallons per minute, which is small in relation to the reactor cavitys makeup system. Nonetheless, the ongoing inspection of the Unresolved Item (NRC Inspection Report 50-247/2010-002, dated May 13, 2010, URI No.0500247/2010002-02, ML1013302140) includes the evaluation of the design description in the UFSAR as part of our independent assessment of the licensees operability and reportability determinations specific to the Indian Point case.
Enclosure