ML14281A124
| ML14281A124 | |
| Person / Time | |
|---|---|
| Site: | Seabrook  |
| Issue date: | 09/25/2014 |
| From: | Gavutis S C-10 Research & Education Foundation |
| To: | Annette Vietti-Cook NRC/SECY |
| SECY/RAS | |
| References | |
| PRM-50-109 | |
| Download: ML14281A124 (5) | |
Text
PETITION FOR RULEMAKING This petition for rulemaking is submitted pursuant to 10 CFR 2.802 by the C-10 Research and Education Foundation with assistance from the Union of Concerned Scientists. The petitioner requests that the U.S. Nuclear Regulatory Commission (NRC), following notice and opportunity for comment, amend its regulations to provide better protection against concrete degradation at U.S. nuclear power plants.
I. STATEMENT OF PETITIONER'S INTEREST The C-10 Research and Education Foundation (C
-10) was established in 1991 to address the health and safety issues related to the Seabrook Station nuclear power plant. C
-10 is a non-profit 501(c)(3) organization that evolved from Citizens Within the Ten
-Mile Radius, a 5,000 member organization founded in 1986 to challenge evacuation plans for the Seabrook Station reactor.
The organization's website (http://c-10.org/) contains additional information.
C-10 has been engaging the NRC about concrete degradation at Seabrook since December 22, 2011. C-10 has been actively monitoring this issue since that time. The Union of Concerned Scientists (UCS) has worked with C-10 on this issue since 2012 and assisted C-10 in preparing this petition.
II. BACKGROUND On June 1, 2010, NextEra Energy Seabrook Station submitted an application to the Nuclear Regulatory Commission (NRC) for a license renewal to the year 2050, 20 years in advance of their current license expiration of 2030.
On December 22, 2011, C-10 requested information from the NRC regarding Seabrook's concrete degradation in several safety related buildings and structures. On September 13, 2012, C-10 and UCS requested that the NRC require NextEra to conduct complete systematic testing and assessment of Seabrook Station's containment to determine the current status of degradation of the concrete and corrosion of steel due to alkali-silica reaction (ASR) concrete degradation.
At an NRC public meeting at Seabrook Station on June 24 , 2014, C-10 asked if the NRC was investigating the US nuclear fleet for ASR concrete degradation. The NRC staff responded that ASR concrete degradation could be adequately indicated through visual examination.
C-10 believes that the reliance on a visual inspection will not adequately identify ASR, does not confirm ASR, or provide the current state of ASR damage (if present) without petrographic analysis under current existing code.
III. PROPOSED ACTIONS C-10 petitions the requests to the NRC to revise applicable regulations to:
- 1. Require that all licensees comply with ACI 349.3R
- 2. Require that all licensees comply with ASTM C 856
-11, Standard Practice for Petrographic Examination of Hardened Concrete
Petition for Rulemaking: Better Protection Against Concrete Degradation at Nuclear Power Plants September 25, 2014 Page 2 IV. RATIONALE FOR THE CHANGES For years, Seabrook's existing structure monitoring program failed to define, further investigate or mitigate the root cause when evidence of concrete degradation was present.
NextEra stated on page 30 of the enclosure to its response dated December 17, 2010, to the N RC (ADAMS ML103540534)) that "visual examination of concrete containment surface (VT
-3C) inspection results from October 2005 identified numerous areas of spalled concrete that was equal or exceed a depth of 1 inch." In 2005, NextEra had not adopted ACI 349.34R
-02 although it had been "recommended" by the NRC. Furthermore, ACI 349.3R
-02 Sec. 5 states, "spalled concrete that exceed a depth of 3/8 inch and 4 inch in any direction must be evaluated. On page 31, the NRC reports, " Five action requests (AR) were issued during ASME Section XI, IWL examinations of containment concrete, eighty-four (84) deficient areas were identified that required an engineering evaluation." NextEra never ha d a code certified "responsible engineer" doing the visual inspections and the NRC was unaware that Seabrook was not following the recommended code inspection requirements.
It is understood and required when structural degradation is occurring it is critical to determine the root cause, and confirm the form of degradation. The NRC has repeatedly stated that ASR is confirmed only through petrographic examinations in accordance with ASTM code. In the second paragraph under Section 3.0 Diagnosis, of the enclosure to its submittal to the NRC dated May 1, 2013, (ADAMS ML13151A328), NextEra stated:
The first core samples were removed in April and May of 2010.
Twelve core samples were taken from the lower electrical tunnel in the Control building.
This area was selected because, qualitatively, it had the most significant groundwater intrusion, and the walls show the most extensive pattern cracking and secondary deposits. The initial visual examination of the core samples was positive - the core samples displayed the visual characteristics of high quality, competent concrete and proper concrete placement procedures.
However, subsequent quantitative testing revealed a reduction in concrete strength and elasticity modulus (Young's modulus). Petrographic examinations in accordance with ASTM C856 identified the presence of ASR.
Since April 2012, C
-10 and UCS have been providing Dr. Paul Brown's commentaries to the NRC to provide expert clarification of the science in this specialized field of material science. On December 2, 2012, Dr. Brown offered the scientific basis for challenging the central hypothesis in NextEra's report titled "Impact of ASR on Concrete Structures and Attachments" (ADAMS ML12151A396) "that confinement reduces cracking, and taking a core bore to test would no longer represent the context of the structure once removed from the structure as invalid." The NRC did not challenge NextEra's hypothesis to our knowledge, despite existing documentation from NRC research and expert submitted commentaries to its contrary. NRC position paper "In situ Monitoring of ASR
-affected Concrete" prepared by Angela Buford states on page 3 , "ASR can exist in concrete without indications of pattern cracking. In addition, in ASR
-affected structures with reinforcement close to the surface or in heavily reinforced structures, surface cracking may be suppressed while internal damage exists throughout the section
." This paper states on page 4, "For concrete in the field, the surface indications sometimes poorly correlate to the extent of ASR degradation within the concrete". Furthermore, on page 5 it states, "For some structures exposed to ASR, internal damage occurs through the depth of the section but visible cracking is suppressed by heavy reinforcement. Crack mapping alone to determine ASR effects on the structure does not allow for the consideration of rebar stresses."
Petition for Rulemaking: Better Protection Against Concrete Degradation at Nuclear Power Plants September 25, 2014 Page 3 The record is abundantly clear that visual inspections alone (a) cannot reliably identify ASR
-affected concrete, and (b) cannot consider associated degradation mechanisms such as rebar stresses. Yet when NextEra determined 131 locations with "assumed" ASR visual signs within multiple power-block structures during 2012, further engineering evaluation s were not done. Since the NRC discovered this situation, the NRC has not required Seabrook to test criteria requiring an engineering evaluation with a single core bore taken from containment to confirm ASR suspicions or required any certified lab testing of key material properties to determine the extent of condition or obtain the data necessary to monitor the rate of progression.
Codes and standards exist that are capable of detecting ASR and determining the key material properties needed to evaluate the degree and severity of ASR damage. For example, American Concrete Institute (ACI) Standard 349.3R02 has been endorsed by the NRC (ADAMS ML112241029) as an acceptable method of protecting against excessive ASR concrete degradation. But by merely endorsing an acceptable method, the NRC has allowed its licensees to instead implement alternatives yielding unacceptable results. For example, ACI 349.3R-02 states that the composite team formed to evaluate concrete degradation indications include civil/structural engineers, concrete inspectors and technicians capable of knowing concrete degradation mechanisms and long
-term performance issues. NextEra did not have composite team. In fact, since they became the owners of Seabrook, before the ASR discovery in 2009, they did not even have a trained and dedicated "responsible engineer" conducting the inspections. NextEra had untrained employees conducting the visual examinations of buildings and no one trained engineer conducting the inspections to accurately record the results or trained to take further action as required. NextEra failed to test the concrete despite the extent of cracking visibly increasing for years.
If the NRC had required instead of merely encouraged compliance with existing codes and standards, C-10 believes Seabrook's ASR concrete degradation would have been identified before it caused moderate to severe degradation in all Seabrook seismic ca tegory 1 structures.
The inability of visual inspections to identify concrete degradation is not confined to the ASR experience at Seabrook. Workers identified significant cracking in the concrete wall of the shield building at the Daivs-Besse nuclear plant on October 10, 2011. This degradation was found when a hole was cut through the building's wall to allow the degraded reactor vessel head to be replaced. According to the plant's owner, "Previous visual inspections of the shield building exterior surface performed over many years did not identify any unusual surface defects or symptoms of distress that would have indicated the presence of the subsurface concrete laminar cracking" (ADAMS ML120600056). The owners attributed the cracking to moisture blown into the concrete wall's pores during a severe winter storm in 1978. Thus, the concrete degradation remained undetected by visual inspections for up to 33 years. Even if visual inspections for concrete degradation were adequately reliable
-which ample "concrete" evidence demonstrates to be the case
-they would still be insufficient due to their limited scope. Visual inspections can only examine exterior surfaces. Many portions of concrete buildings simply cannot be visually inspected. The below grade portions, those regions most likely to be exposed to groundwater and thus most likely vulnerable to ASR, cannot be examined. It is imperative that more reliable means of monitoring the condition of concrete be performed to detect degradation before it becomes so pervasive that even the unreliable, limited
-scope visual inspections notice it.
Petition for Rulemaking: Better Protection Against Concrete Degradation at Nuclear Power Plants September 25, 2014 Page 4 V. CONCLUSION C-10 petitions the NRC to require its licensees comply with industry codes and standards already endorsed by the agency. Visual inspections have been repeatedly proven unable to reliably monitor concrete conditions and prevent significant degradation. The NRC
-endorsed codes and standards provide better protection against safety margin erosion caused by concrete degradation.
Thus, the proposed actions requested by the petitioners could be implemented by the NRC as expeditiously as possible.