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SECY-03-0095

June 6, 2003

• PURPOSE
• BACKGROUND
• DISCUSSION
• SUMMARY
• COORDINATION

PURPOSE:

To inform the Commission of the staff's intent to issue the subject generic letter. In the generic letter, the staff asks the licensees of nuclear power reactors to provide information that enables the NRC staff to verify whether licensees can demonstrate that their control room complies with and is maintained in accordance with their control room habitability licensing and design bases. The objective is to ensure that licensees are in compliance with the licensing and design bases of their facilities with respect to the onsite dose consequences specified in General Design Criterion 19 of Appendix A to Part 50 of Title 10 of the Code of Federal Regulations or related commitments made on a plant-specific basis. A copy of the proposed generic letter is attached.

BACKGROUND:

The control room is the plant area from which operators take actions to operate the plant safely under normal conditions and maintain the reactor in a safe condition during accident situations. Control room habitability systems (CRHS) of nuclear power plants provide the functions necessary to ensure that the control room operators can remain in the control room and take actions to operate the plant under normal and accident conditions. To ensure that the CRHS will perform in a manner that is consistent with the licensing basis of a facility, most licensees have requirements in their facility technical specifications to periodically test parameters important to habitability. One such parameter is the integrity of the control room.

DISCUSSION:

The NRC has been working with the nuclear industry on concerns associated with control room habitability. Control room integrity is one of these concerns since recent improved testing methods have shown that control rooms are not as leak-tight as was originally assumed in many design analyses. This reduced leak-tightness is significant because radiological doses and the impact of hazardous chemicals to control room operators depend on the amount of inleakage. Additionally, the impact of smoke byproducts on control room habitability is not addressed by current regulations, and regulatory guidance since these were developed assuming an essentially leak-tight control room.

Since 1992, the licensees for about 30 percent of the U.S. commercial power reactors have tested their control room for inleakage. These licensees followed American Society for Tests and Measurements E741, "Standard Test Methods for Determining Air Change in a Single Zone by Means of a Tracer Gas Dilution." All but one of the control rooms tested failed to meet the design basis inleakage.

Licensees and NRC staff have identified other deficiencies in CRHS design, operation and performance. The NRC staff discussed some of these deficiencies in Regulatory Issue Summary 2001-19, "Deficiencies in the Documentation of Design Basis Radiological Analyses Submitted in Conjunction with License Amendment Requests." Also, a group of licensees had difficulty meeting the control room criteria in Three Mile Island (TMI) Action Plan Item III.D.3.4, "Control Room Habitability Requirements," which the NRC ordered most licensees to implement after the accident at TMI. The staff allowed these licensees to take compensatory actions and to postpone changing their control rooms until ongoing radiological source term research was completed or until the NRC issued a generic letter on control room habitability.

The draft generic letter was published for comment in the Federal Register (67 FR 31385) on May 9, 2002. The staff received seven letters from nuclear industry organizations responding to the draft generic letter. From the seven letters the staff identified 35 comments; of these comments 18 were redundant, leaving 17 distinct comments. The majority of these comments were clarifications and editorial in nature. All comments were dispositioned and documented in the Agencywide Documents Access and Management System at ML030780493.

The staff believes that the currently identified habitability deficiencies of most control rooms have been repaired or controlled by temporary, compensatory measures and that they do not adversely affect control room habitability or public health and safety. Given the low probability of a design basis accident and the conservatism inherent in the design basis dose calculations, including the conservatism in the design basis source term, this issue is not an immediate safety concern. Therefore, the staff believes that the time frame in the generic letter for resolution of this matter is appropriate.

The NRC staff developed the proposed generic letter considering the NRC's four performance goals. The approach maintains safety and reduces unnecessary regulatory burden through licensee voluntary correction of identified deficiencies that do not currently warrant stronger regulatory action. To make this activity and its decisions more effective, efficient and realistic and to address public confidence, the NRC staff developed the generic letter using extensive public interactions with industry groups and public workshops held in each NRC region.

SUMMARY:

The staff intends to issue this generic letter just prior to an industry workshop scheduled for June 17-18, 2003.

COORDINATION:

The Advisory Committee on Reactor Safeguards (ACRS) reviewed the generic letter during its 501^st meeting on April 10, 2003. The ACRS recommended that the generic letter should be issued. The Committee To Review Generic Requirements (CRGR) reviewed the generic letter during its 384^th meeting on April 22, 2003. The staff incorporated the CRGR comments into the generic letter.

The Office of the General Counsel reviewed this generic letter and had no legal objections to its content.

Attachment:

NRC Generic Letter 2003-XX: Control Room Habitability

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